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Archive for the ‘Regulated Clinical Trials: Design, Methods, Components and IRB related issues’ Category

Nanotechnology and HIV/AIDS Treatment

Author: Tilda Barliya, PhD

 

AIDS was first reported in 1981 followed by the identification of HIV as the cause of the disease in 1983 and is now a global pandemic that has become the leading infectious killer of adults worldwide. By 2006, more than 65 million people had been infected with the HIV virus worldwide and 25 million had died of AIDS (Merson MH. The HIV-AIDS pandemic at 25 – the global response. (1, 2). This has caused tremendous social and economic damage worldwide, with developing countries, particularly Sub-Saharan Africa, heavily affected.

A cure for HIV/AIDS has been elusive in almost 30 years of research. Early treatments focused on antiretroviral drugs that were effective only to a certain degree. The first drug, zidovudine, was approved by the US FDA in 1987, leading to the approval of a total of 25 drugs to date, many of which are also available in fixed-dose combinations and generic formulations for use in resource-limited settings (to date, only zidovudine and didanosine are available as true generics in the USA).

However, it was the advent of a class of drugs known as protease inhibitors and the introduction of triple-drug therapy in the mid-1990s that revolutionized HIV/AIDS treatment (3,4). This launched the era of highly active antiretroviral therapy (HAART), where a combination of three or more different classes of drugs are administered simultaneously.

Challenges of HIV/AIDS treatment

  • HIV resides in latent cellular and anatomical reservoirs where current drugs are unable to completely eradicate the virus.
  • Macrophages are major cellular reservoirs, which also contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination.
  • Anatomical latent reservoirs include secondary lymphoid tissue, testes, liver, kidney, lungs, the gut and the brain.
  • The major challenge facing current drug regimens is that they do not fully eramacrdicate the virus from these reservoirs; requiring patients take medications for life. Under current treatment, pills are taken daily, resulting in problems of patient adherence. The drugs also have side effects and in some people the virus develops resistance against certain drugs.

Current treatment in HIV/AIDS

The use of the HAART regimen, particularly in the developed world, has resulted in tremendous success in improving the expectancy and quality of lives for patients. However, some HAART regimens have serious side effects and, in all cases, HAART has to be taken for a lifetime, with daily dosing of one or more pills. Due to the need to take the medication daily for a lifetime, patients fail to adhere to the treatment schedule, leading to ineffective drug levels in the body and rebound of viral replication.Some patients also develop resistance to certain combinations of drugs, resulting in failure of the treatment. The absence of complete cure under current treatment underscores the great need for continued efforts in seeking innovative approaches for treatment of HIV/AIDS.

Drug resistance is mainly caused by the high genetic diversity of HIV-1 and the continuous mutation it undergoes. This problem is being addressed with individualized therapy, whereby resistance testing is performed to select a combination of drugs that is most effective for each patient (5). In addition, side effects due to toxicities of the drugs are also a concern. There are reports that patients taking HAART experience increased rates of heart disease, diabetes, liver disease, cancer and accelerated aging. Most experts agree that these effects could be due to the HIV infection itself or co-infection with another virus, such as co-infection with hepatitis C virus resulting in liver disease. However, the toxicities resulting from the drugs used in HAART could also contribute to these effects.

Under current treatment, complete eradication of the virus from the body has not been possible. The major cause for this is that the virus resides in ‘latent reservoirs’ within memory CD4+ T cells and cells of the macrophage–monocyte lineage. A major study recently found that, in addition to acting as latent reservoirs, macrophages significantly contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination (6).  The cells that harbor latent HIV are typically concentrated in specific anatomic sites, such as secondary lymphoid tissue, testes, liver, kidney, lungs, gut and the CNS. The eradication of the virus from such reservoirs is critical to the effective long-term treatment of HIV/AIDS patients.

Therefore, there is a great need to explore new approaches for developing nontoxic, lower-dosage treatment modalities that provide more sustained dosing coverage and effectively eradicate the virus from the reservoirs, avoiding the need for lifetime treatments.

Nanotechnology for HIV/AIDS treatment

The use of nanotechnology platforms for delivery of drugs is revolutionizing medicine in many areas of disease treatment.

Nanotechnology-based platforms for systemic delivery of antiretroviral drugs could have similar advantages.

  • Controlled-release delivery systems can enhance their half-lives, keeping them in circulation at therapeutic concentrations for longer periods of time. This could have major implications in improving adherence to the drugs.
  • Nanoscale delivery systems also enhance and modulate the distribution of hydrophobic and hydrophilic drugs into and within different tissues due to their small size. This particular feature of nanoscale delivery systems appears to hold the most promise for their use in clinical treatment and prevention of HIV. Specifically, targeted delivery of antiretroviral drugs to CD4+ T cells and macrophages as well as delivery to the brain and other organ systems could ensure that drugs reach latent reservoirs
  • Moreover, by controlling the release profiles of the delivery systems, drugs could be released over a longer time and at higher effective doses to the specific targets. Figure 1. Various nanoscale drug delivery systems.

Optional treatments:

  •    Antiretroviral drugs
  •    Gene Therapy
  •    Immune Therapy
  •    Prevention

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The use of nanotechnology systems for delivery of antiretroviral drugs has been extensively reviewed by Nowacek et al. and Amiji et al. (7,8).

In a recent study based on polymeric systems, nanosuspensions (200 nm) of the drug rilpivirine (TMC278) stabilized by polyethylene. A series of experiments by Dou et al. showed that nanosuspension of the drug indinavir can be stabilized by a surfactant system comprised of Lipoid E80 for effective delivery to various tissues. The indinavir nanosuspensions were loaded into macrophages and their uptake was investigated. Macrophages loaded with indinavir nanosuspensions were then injected intravenously into mice, resulting in a high distribution in the lungs, liver and spleen. More significantly, the intravenous administration of a single dose of the nanoparticle-loaded macrophages in a rodent mouse model of HIV brain infection resulted in significant antiviral activity in the brain and produced measureable drug levels in the blood up to 14 days post-treatment.polypropylene glycol (poloxamer 338) and PEGylated tocopheryl succinate ester (TPGS 1000) were studied in dogs and mice. A single-dose administration of the drug in nanosuspensions resulted in sustained release over 3 months in dogs and 3 weeks in mice, compared with a half-life of 38 h for free drug. These results serve as a proof-of-concept that nanoscale drug delivery may potentially lower dosing frequency and improve adherence.

Active targeting strategies have also been employed for antiretroviral drug delivery. Macrophages, which are the major HIV reservoir cells, have various receptors on their surface such as formyl peptide, mannose, galactose and Fc receptors, which could be utilized for receptor-mediated internalization. The drug stavudine was encapsulated using various liposomes (120–200 nm) conjugated with mannose and galactose, resulting in increased cellular uptake compared with free drug or plain liposomes, and generating significant level of the drug in liver, spleen and lungs. Stavudine is a water-soluble drug with a very short serum half-life (1 h). Hence, the increased cellular uptake and sustained release in the tissues afforded by targeted liposomes is a major improvement compared with free drug. The drug zidovudine, with half-life of 1 h and low solubility, was also encapsulated in a mannose-targeted liposome made from stearylamine, showing increased localization in lymph node and spleen. An important factor to consider here is that although most of the nucleoside drugs such as stavudine and zidovudine have short serum half-lives, the clinically relevant half-life is that of the intracellular triphosphate form of the drug. For example, despite zidovudine’s 1 h half-life in plasma, it is dosed twice daily based on intracellular pharmacokinetic and clinical efficacy data. Therefore, future nanotechnology-based delivery systems will have to focus in showing significant increase of the half-lives of the encapsulated drugs to achieve a less frequent dosing such as once weekly, once-monthly or even less.

Gene Therapy for HIV/AIDS

In addition to improving existing antiretroviral therapy, there are ongoing efforts to discover alternative approaches for treatment of HIV/AIDS. One promising alternative approach is gene therapy, in which a gene is inserted into a cell to interfere with viral infection or replication. Other nucleic acid-based compounds, such as DNA, siRNA, RNA decoys, ribozymes and aptamers or protein-based agents such as fusion inhibitors and zinc-finger nucleases can also be used to interfere with viral replication.

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RNAi is also considered to have therapeutic potential for HIV/AIDS. Gene silencing is induced by double stranded siRNA, which targets for destruction

he mRNA of the gene of interest. For HIV/AIDS, RNAi can either target the various stages of the viral replication cycle or various cellular targets involved in viral infection such as CD4, CCR5, and/or CXCR4, the major cell surface co-receptors responsible for viral entry. HIV replicates by reverse transcription to form DNA and uses the DNA to produce copies of its mRNA for protein synthesis; siRNA therapy could be used to knock down this viral mRNA. As with other gene therapy techniques, delivery of siRNA to specific cells and tissues has been the major challenge in realizing the potential of RNAi.

New nanotechnology platforms are tackling this problem by providing nonviral alternatives for effective and safe delivery. The first nontargeted delivery of siRNA in humans via self-assembling, cyclodextrin polymer-based nanoparticles for cancer treatment have recently entered Phase I clinical trials.

Although at an early stage, nonviral delivery of siRNA for treatment of HIV infection is also gaining ground. A fusion protein, with a peptide transduction domain and a double stranded RNA-binding domain, was used to encapsulate and deliver siRNA to T cells in vivo. CD4- and CD8-specific siRNA delivery caused RNAi responses with no adverse effects such as cyto-toxicity or immune stimulation. Similarly, a protamine-antibody fusion protein-based siRNA delivery demonstrated that siRNA knockdown of the gag gene can inhibit HIV replication in primary T cells

Single-walled nanotubes were shown to deliver CXCR4 and CD4 specific siRNA to human T cells and peripheral blood mononuclear cells. Up to 90% knockdown of CXCR4 receptors and up to 60% knockdown of CD4 expression on T cells was observed while the knockdown of CXCR4 receptors on peripheral blood mononuclear cells was as high as 60%. In a separate study, amino-terminated carbosilane dendrimers (with interior carbon-silicon bonds) were used for delivery of siRNA to HIV-infected lymphocytes.

These pioneering studies demonstrate that nonviral siRNA delivery is possible for HIV/AIDS treatment. However, more work needs to be done in optimizing the delivery systems and utilizing designs for efficient targeting and intracellular delivery. The recent developments in polymer- and liposome-based siRNA delivery systems could be optimized for targeting cells that are infected with HIV, such as T cells and macrophages. Moreover, since HIV mutates and has multiple strains with different genetic sequences, combination siRNA therapy targeting multiple genes should be pursued. For these applications, nanotechnology platforms with capability for co-delivery and targeting need to be developed specifically for HIV-susceptible cells. A macrophage and T-cell-targeted and nanotechnology-based combination gene therapy may be a promising platform for efficient HIV/AIDS treatment.

Immunotherapy for HIV/AIDS

The various treatment approaches described above focus on treating HIV/AIDS by directly targeting HIV at the level of the host cell or the virus itself. An alternative approach is immunotherapy aimed at modulating the immune response against HIV. CD8+ cytotoxic T-cell responses to acute HIV infection appear to be relatively normal, while neutralizing antibody production by B cells is delayed or even absent.

Immunotherapy is a treatment approach involving the use of immunomodulatory agents to modulate the immune response against a disease. Similar to vaccines, it is based on immunization of individuals with various immunologic formulations; however, the purpose is to treat HIV-infected patients as opposed to protect healthy individuals (preventive vaccines will be discussed in an upcoming section). The various immunotherapy approaches for HIV/AIDS could be based on delivering cytokines (such as IL-2, IL-7 and IL-15) or antigens. The development of cellular immunity, and to a large degree humoral immunity, requires antigen-presenting cells (APCs) to process and present antigens to CD4+and CD8+ T cells. Dendritic cells (DCs) are the quintessential professional APCs responsible for initiating and orchestrating the development of cellular and humoral (antibody) immunity.

Various polymeric systems have been explored for in vivo targeting of DCs and delivery of small molecules, proteins or DNAs showing potential for immunotherapy. Poly(ethylene glycol) (PEG) stabilized poly(propylene sulfide) polymer nanoparticles accumulated in DCs in lymph nodes. Following nanoparticle injection, DCs containing nanoparticles accumulated in lymph nodes, peaking at 4 days with 40–50% of DCs and other APCs having internalized nanoparticles.

In another study, nanoparticles of the copolymer poly(D,L-lacticide-co-glycolide) (PLGA) showed efficient delivery of antigens to murine bone marrow-derived DCs in vitro, suggesting their potential use in immunotherapy. More recently, a very interesting work showed that HIV p24 protein adsorbed on the surface of surfactant-free anionic poly(D,L-lactide) (PLA) nanoparticles were efficiently taken-up by mouse DCs, inducing DC maturation. he p24-nanoparticles induced enhanced cellular and mucosal immune responses in mice. Although this targeting is seen in ex vivo-generated DCs and not in vivo DCs, the efficient delivery of the antigen to DCs through the nanoparticles is an important demonstration that may eventually be applied to in vivo DC targeting.

Clinical Trial

he most clinically advanced application of nanotechnology for immunotherapy of HIV/AIDS is the DermaVir patch that has reached Phase II clinical trials (9). DermaVir is a targeted nanoparticle system based on polyethyleimine mannose (PEIm), glucose and HIV antigen coding DNA plasmid formulated into nanoparticles (~100 nm) and administered under a patch after a skin preparation. The nanoparticles are delivered to epidermal Langerhans cells that trap the nanoparticles and mature to become highly immunogenic on their way to the lymph nodes. Mature DCs containing the nanoparticles present antigens to T cells inducing cellular immunity. Preclinical studies and Phase I clinical trials showed safety and tolerability of the DermaVir patch, which led the progression to Phase II trials. This is the first nanotechnology-based immunotherapy for HIV/AIDS that has reached the clinic and encourages further work in this area.

Table 1

Summary of nanotechnology-based treatment approaches for HIV/AIDS.

Type of therapy Therapeutic agent (drug or gene) Nanotechnology delivery platform Development stage Refs.
Antiretroviral therapy Rilpivirine (TMC278) Poloxamer 338/TPGS 1000 Preclinical [35]
Indinavir Liposome-laden macrophages Preclinical [3638]
Stavudine Mannose- and galactose-targeted liposome Preclinical [3941]
Zidovudine Mannose-targeted liposome Preclinical [42]
Efavirenz Mannose-targeted dendrimer Preclinical [43,45]
Lamivudine Mannose-targeted dendrimer Preclinical [46]
Nanomaterials Fullerene derivatives Preclinical [4955]
Dendrimers Preclinical [56,57]
Silver nanoparticles Preclinical [58,59]
SDC-1721/gold nanoparticles Gold nanoparticles Preclinical [60]
Gene therapy siRNA Peptide fusion proteins, protamine–antibody fusion proteins, dendrimers, single walled carbon nanotubes, peptide–antibody conjugates Preclinical [7781]
Immunotherapy P24 protein Poly (D,L-lactide) nanoparticles/dendritic cells Preclinical [98]
Plasmid DNA Mannose-targeted polyethyleimine polymers Phase II clinical trials [99]

Note:  to open the references in the table 1, please go to ref 1 in this post to see full ref info.

Nanotechnology for HIV/AIDS prevention

The search for a safe and effective HIV/AIDS vaccine has been challenging in the almost three decades since the discovery of the disease. Recently, high-profile clinical trial failures have prompted great debate over the vaccine research, with some suggesting the need for a major focus on fundamental research, with fewer efforts on clinical trials.

The major challenges in the development of a preventive HIV/AIDS vaccine have been the extensive viral strain and sequence diversity, viral evasion of humoral and cellular immune responses, coupled with the lack of methods to elicit broadly reactive neutralizing antibodies and cytotoxic T cells. The challenge associated with delivery of any exogenous antigen (such as nanoparticles) to APCs, is that exogenous antigens require specialized ‘cross-presentation’ in order to be presented by MHC class I and activate CD8+cytotoxic T cells.

his requirement for cytosolic delivery of antigens and cross-presentation represents yet another hurdle for HIV intracellular antigen vaccine, but potentially an advantage of nanodelivery. Humoral responses (neutralizing antibodies produced by B cells) are generated to intact antigen presented on the surface for the virus, or nanoparticles, but these humoral responses typically require ‘help’ from CD4+ T cells, but rather both. Nanoparticles have potential as adjuvants and delivery systems for vaccines. Table 2 present the different approaches.

Table 2

Summary of nanotechnology developments for prevention of HIV/AIDS.

Type of preventive agent Antigen/adjuvant or drug Nanotechnology platform Development stage Refs.
Protein or peptide vaccine gp41, gp120, gp160, p24, Env, Gag, Tat Liposomes, nanoemulsion, MF59, PLA nanoparticles, poly(γ-glutamic acid) nanoparticles Preclinical [108111]
[119120]
[122125]
[128130]
DNA vaccine env, rev, gag, tat, CpG ODN Liposomes, nanoemulsion, PLA nanoparticles Preclinical [115,121]
Inactivated viral particle Inactivated HIV viral particle Polystyrene nanospheres Preclinical [126127]
Microbicides L-lysine dendrimer L-lysine dendrimer Phase I/II [136138]
PLGA nanoparticles
PSC-RANTES PLGA Preclinical [139]
siRNA Nanoparticles, lipids, cholesterol conjugation Preclinical [141144]

ODN: Oligonucleotides; PLA: Poly(D,L-lactide); PLGA: Poly(D,L-lacticide-co-glycolide).

Note:  to open the references in the table 2, please go to ref 1 in this post to see full ref info.

 

Summary

Nanotechnology can impact the treatment and prevention of HIV/AIDS with various innovative approaches. Treatment options may be improved using nanotechnology platforms for delivery of antiretroviral drugs. Controlled and sustained release of the drugs could improve patient adherence to drug regimens, increasing treatment effectiveness.

While there is exciting potential for nanomedicine in the treatment of HIV/AIDS, challenges remain to be overcome before the potential is realized. These include toxicity of nanomaterials, stability of nanoparticles in physiological conditions and their scalability for large-scale production. These are challenges general to all areas of nanomedicine and various works are underway to tackle them.

Another important consideration in investigating nanotechnology-based systems for HIV/AIDS is the economic aspect, as the hardest hit and most vulnerable populations reside in underdeveloped and economically poor countries. In the case of antiretroviral therapy, nanotherapeutics may increase the overall cost of treatment, reducing the overall value. However, if the nanotherapeutics could improve patient adherence by reducing dosing frequency as expected, and furthermore, if they can eradicate viral reservoirs leading to a sterile immunity, these advantages may effectively offset the added cost.

 

Ref:

1. Mamo T, Moseman EA., Kolishetti N., Salvadoe-Morales C., Shi J., Kuritzkes DR., Langer R., von-Adrian U and Farokhzad OF.   Emerging nanotechnology approaches for HIV/AIDS treatment and prevention. Nanomedicine (Lond) 2010; 5(2): 269-295.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861897/

2. Merson MH. The HIV-AIDS pandemic at 25 – the global response. N Engl J Med.2006;354(23):2414–2417

3. Walensky RP, Paltiel AD, Losina E, et al. The survival benefits of AIDS treatment in the United States. J Infect Dis. 2006;194(1):11–19

4. Richman DD, Margolis DM, Delaney M, Greene WC, Hazuda D, Pomerantz RJ. The challenge of finding a cure for HIV infection. Science. 2009;323(5919):1304–1307)

5.Sax PE, Cohen CJ, Kuritzkes DR. HIV Essentials. Physicians’ Press; Royal Oak, MI, USA: 2007.

6. Lamers SL, Salemi M, Galligan DC, et al. Extensive HIV-1 intra-host recombination is common in tissues with abnormal histopathology. PLoS One. 2009;4(3):E5065.

7. Vyas TK, Shah L, Amiji MM. Nanoparticulate drug carriers for delivery of HIV/AIDS therapy to viral reservoir sites. Expert Opin Drug Deliv. 2006;3(5):613–628.

8. Amiji MM, Vyas TK, Shah LK. Role of nanotechnology in HIV/AIDS treatment: Potential to overcome the viral reservoir challenge. Discov Med. 2006;6(34):157–162

9. Lori F, Calarota SA, Lisziewicz J. Nanochemistry-based immunotherapy for HIV-1. Curr Med Chem. 2007;14(18):1911–1919

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Author:  Sreedhar Tirunagari, MD

Human subject recruitment is crucial for the success of any clinical trial and can be a challenging to Sponsors and investigators, hence they use four main strategies to recruit human subjects and encourage timely recruitment.

  •  Sponsors offer financial and other incentives to investigators to boost enrollment.
  •  Investigators target their own patients as potential subjects.
  •  Investigators seek additional subjects from other sources such as physician referrals and disease registries.
  •  Sponsors and investigators advertise and promote their studies.

To achieve timely recruitment for clinical trial the consent process may be undermined when, under pressure of quick recruitment like patients are influenced to participate in research due to their trust in their doctor. Some physicians searching medical records, disease registries, school records, or mailing lists by compromising confidentiality and then contacting a patient about participation. Some times there may be chance of enrollment of Ineligible Subjects in order to meet quotas and satisfy sponsors.

Most IRB’s are not reviewing many of the recruitment practices that they and others find most troubling. IRBs’ limited review of recruitment practices is in part due to their perceived lack of authority to review certain practices in their own oversight of research sites, sponsors pay minimal attention to how human subjects are recruited.

Role of IRB:
IRBs should concentrate on human subject recruitment consent process; how they are enrolled in to study and human subject protection and confidentiality is maintained. Few recommendations suggested by the Department of Health and Human Services in its report can be adopted to ensure essential human-subject protections without unnecessarily slowing the pace of research and discovery.

  •  IRB should be provided with direction regarding oversight of recruitment practices.

IRB should be given authority to review recruitment practices, Regulatory bodies should disseminate guidance explicitly stating this authority based on IRBs’ established authority to ensure informed consent and review anything related to human-subject protections.

Regulatory bodies should also suggest a recruitment question to the IRB’s that they should address in their protocol reviews and should foster discussion about these issues.

  •  Development of guidelines for all parties on appropriate recruiting practices :

Determination of appropriate recruiting practices would be helpful for all parties like; sponsors, investigators, and IRBs. It is essential that this determination be made cooperatively with industry and the research community. As part of their deliberations, these parties could explore such questions as:
• Is it acceptable for sponsors to offer bonuses to investigators for successfully recruiting subjects?
• Should physicians be allowed to receive fees for referring their patients as potential subjects for a clinical trial?
• Should the financial arrangements between sponsors and investigators be disclosed to potential subjects?
• Do searching medical records for potential subjects constitute a breach of confidentiality?

  •  IRBs and investigators should be adequately educated about human-subject protections :

• Investigators should be educated as a prerequisite for conducting research under regulatory guidelines.
• IRBs should develop training program for members.
• Require more extensive representation on IRBs of nonscientific and non- institutional members. Such members can help sensitize IRBs to patient concerns about recruitment practices.

• All the IRBs should be registered with the Country specific regulatory bodies.

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Author: Tilda Barliya PhD

Metastasis, the spread of cancer cells from a primary tumour to seed secondary tumours in distant sites, is one of the greatest challenges in cancer treatment today. For many patients, by the time cancer is detected, metastasis  has already occurred. Over 80% of patients diagnosed  with lung cancer, for example, present with metastatic  disease. Few patients with metastatic cancer are cured by surgical intervention, and other treatment modalities are limited. Across all cancer types, only one in five patients diagnosed with metastatic cancer will survive more than 5 years. (1,2).

Metastatic Cancer 

  • Metastatic cancer is cancer that has spread from the place where it first started to another place in the body.
  • Metastatic cancer has the same name and same type of cancer cells as the original cancer.
  • The most common sites of cancer metastasis are the lungs, bones, and liver.
  • Treatment for metastatic cancer usually depends on the type of cancer and the size, location, and number of metastatic tumors.

How do cancer cells spread (3)

  • Local invasion: Cancer cells invade nearby normal tissue.
  • Intravasation: Cancer cells invade and move through the walls of nearby lymph vessels or blood vessels.
  • Circulation: Cancer cells move through the lymphatic system and the bloodstream to other parts of the body.

The ability of a cancer cell to metastasize successfully depends on its individual properties; the properties of the noncancerous cells, including immune system cells, present at the original location; and the properties of the cells it encounters in the lymphatic system or the bloodstream and at the final destination in another part of the body. Not all cancer cells, by themselves, have the ability to metastasize. In addition, the noncancerous cells at the original location may be able to block cancer cell metastasis. Furthermore, successfully reaching another location in the body does not guarantee that a metastatic tumor will form. Metastatic cancer cells can lie dormant (not grow) at a distant site for many years before they begin to grow again, if at all.

Although cancer therapies are improving, many drugs are not reaching the sites of metastases, and doubt  remains over the efficacy of those that do. Methods  that are effective for treating large, well-vascularized tumours may be inadequate when dealing with small clusters of disseminated malignant cells.

We expect that the expanding capabilities of nanotechnology, especially in targeting, detection and particle trafficking, will enable  novel approaches to treat cancers even after metastatic dissemination.

 

Lymph nodes, which are linked by lymphatic vessels, are distributed throughout the body and have an integral role in the immune response. Dissemination of cancer cells through the lymph network is thought to be an important route for metastatic spread. Tumor proximal lymph nodes are often the first site of metastases, and the presence of lymph node metastases signifies further metastatic spread and poor patient survival.

As such, lymph nodes have been targeted using cell-based nanotechnologies

Lymph nodes are small, bean-shaped organs that act as filters along the lymph fluid channels. As lymph fluid leaves the organ (such as breast, lung etc) and eventually goes back into the bloodstream, the lymph nodes try to catch and trap cancer cells before they reach other parts of the body. Having cancer cells in the lymph nodes suggests an increased risk of the cancer spreading. It is thus very important to evaluate the involvement of lymph nodes when choosing the best possible treatment for the patient.

Although current mapping methods are available such as CT and MRI scans, PET scan, Endobronchial Ultrasound, Mediastinoscopy and lymph node biopsy, sentinel lymph node (SLN) mapping and nodal treatment in lung cancer remain inadequate for routine clinical use. 

Certain characteristics are associated with preferential (but not exclusive) nanoparticle trafficking to lymph nodes following intravenous administration.

Targeting is often an indirect process, as receptors on the surface of leukocytes bind nanoparticles and transfer them to lymph nodes as part of a normal immune response. Several strategies have been used to enhance nanoparticle uptake by leukocytes in circulation. Coating iron-oxide nanoparticles with carbohydrates, such as dextran, results in the increased accumulation of these nanoparticles in lymph nodes. Conjugating peptides and antibodies, such as immunoglobulin G (IgG), to the particle surface also increases their accumulation in the lymphatic network. In general, negatively charged particles are taken up at faster rates than positively charged or uncharged particles. Conversely, ‘stealth’ polymers, such as polyethylene glycol (PEG), on the surface of nanoparticles, can inhibit uptake by leukocytes, thereby reducing accumulation in the lymph nodes.

Lymph node targeting may be achieved by other routes of administration. Tsuda and co-workers reported that non-cationic particles with a size range of 6–34nm, when introduced to the lungs (intrapulmonary administration), are trafficked rapidly (<1 hour) to local lymph nodes. Administering particles <80 nm in size subcutaneously also results in trafficking to lymph nodes. Interestingly, some studies have indicated that non-pegylated particles exhibit enhanced accumulation in the lymphatics and that pegylated particles tend to appear in the circulation several hours after administration.

Over the last twenty years, sentinel lymph node (SLN) imaging has revolutionized the treatment of several malignancies, such has melanoma and breast cancer, and has the potential to drastically improve treatment in other malignancies, including lung cancer. Several attempts at developing an easy, reliable, and effective method for SLN mapping in lung cancer have been unsuccessful due to unique difficulties inherent to the lung and to operating in the thoracic cavity.

An inexpensive method offering rapid, intraoperative identification of SLNs, with minimal risk to both patient and provider, would allow for improved staging in patients. This, in turn, would permit better selection of patients for adjuvant therapy, thus reducing morbidity in those patients for whom adjuvant treatment is inappropriate, and ensuring that those who need this added therapy actually receive it. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109504/)

Current methods for SLN identification involve the use of radioactivity-guided mapping with technetium-99m sulfur colloid and/or visual mapping using vital blue dyes. Unfortunately these methods can be inadequate for SLN mapping in non-small cell lung cancer (NSCLC) The use of vital blue dyes is limited in vivo by poor visibility, particularly in the presence of anthracotic mediastinal nodes, thereby decreasing the signal-to-background ratio (SBR) that enables nodal detection. Similarly, results with technetium-99m sulfur colloid have been mixed when used in the thoracic cavity, where hilar structures and aberrant patterns of lymphatic drainage make detection more difficult.

Although Nomori et al. have reported an 83% nodal identification rate following a preoperative injection of technetium-99 colloid, there is an associated increased risk of pneumothorax and bleeding with this method. Further, the recently completed CALGB 140203 multicenter Phase 2 trial investigating the use of intraoperative technetium-99m colloid found an identification rate of only 51% with this technique.  Clearly a technology with greater accuracy, improved SBR, and less potential risk to surgeon and patient would be welcome in the field of thoracic oncology.

Near-infrared (NIR) fluorescence imaging has the potential to meet this difficult challenge.

Near-Infrared Light

NIR light is defined as that within the wavelength range of 700 to 1000 nm. Although NIR light is invisible to the naked eye, it can be thought of as “redder” than UV and visible light.

  • Absorption, scatter, and autofluorescence are all significantly reduced at redder wavelengths. For instance, Hemoglobin, water, lipids, and other endogenous chromophores, such as melanin, have their lowest absorption within the NIR spectrum, which permits increased photon depth penetration into tissues
  • In addition, imaging can also be affected by photon scatter, which describes the reflection and/or deflection of light when it interacts with tissue. Scatter, on an absolute scale, is often ten-times higher than absorption. However, the two major types of scatter, Mie and Rayleigh, are both reduced in the NIR, making the use of NIR wavelengths especially important for the reduction of photon attenuation.
  • living tissue has extremely high “autofluorescence” in the UV and visible wavelength ranges due to endogenous fluorophores, such as NADH and the porphyrins. Therefore, UV/visible fluorescence imaging of the intestines, bladder, and gallbladder is essentially precluded. However, in the NIR spectrum, autofluorescence is extremely low, providing the black imaging background necessary for optimal detection of a NIR fluorophore within the surgical field
  • Additionally, optical imaging techniques, such as NIR fluorescence, eliminate the need for ionizing radiation. This, combined with the availability of a NIR fluorophore already FDA-approved for other indications and having extremely low toxicity (discussed below), make this a potentially safe imaging modality.

The main disadvantage is that it’s invisible to the human eye, requiring special imaging-systems to “see” the NIR fluorescence.

Currently there are three intraoperative NIR imaging systems in various stages of development:

  • The SPY system (Novadaq, Canada) – utilizes laser light excitation in order to obtain fluorescent images. The Spy system has been studied for imaging patency of vascular anastamoses following CABG and organ transplantation
  • The Photodynamic Eye(Hamamatsu, Japan) – is presently available only in Japan
  • The Fluorescence-Assisted Resection and Exploration (FLARE) system ()- developed by the authors’ laboratory utilizes NIR light-emitting diode (LED) excitation, eliminating the need for a potentially harmful laser. Additionally, the FLAREsystem has the advantage of being able to provide simultaneous color imaging, NIR fluorescence imaging, and color-NIR merged images, allowing the surgeon to simultaneously visualize invisible NIR fluorescence images within the context of surgical anatomy.

Near-Infrared Fluorescent Nanoparticle Contrast Agents

The ideal contrast agent for SLN mapping would be anionic and within 10–50 nm in size in order to facilitate rapid uptake into lymphatic vessels with optimal retention within the SLN.

Due to the lack of endogenous NIR tissue fluorescence, exogenous contrast agents must be administered for in vivo studies. The most important contrast agents that emit within the NIR spectrum are the heptamethine cyanines fluorophores, of which indocyanine green (ICG) is the most widely used, and fluorescent semiconductor nanocrystals, also known as quantum dots (QDs).

  • ICG is an extremely safe NIR fluorophore, with its only known toxicity being rare anaphylaxis. The dye was FDA approved in 1958 for systemic administration for indicator-dilution studies including measurements of cardiac output and hepatic function. Additionally, it is commonly used in ophthalmic angiography. When given intravenously, ICG is rapidly bound to plasma albumin and cleared from the blood via the biliary system. Peak absorption and emission of ICG occur at 780 nm and 830 nm respectively, within the window where in vivo tissue absorption is at its minimum. ICG has a relatively neutral charge, has a hydrodynamic diameter of only 1.2 nm, and is relatively hydrophobic. Unfortunately, this results in rapid transport out of the SLN and relatively low fluorescence yield, thereby decreasing its efficacy in mapping techniques. However, noncovalent adsorption of ICG to human serum albumin (HSA), as occurs within plasma, results in an anionic nanoparticle with a diameter of 7.3 nm and a three-fold increase in fluorescence yield markedly improving its utility in SLN mapping.
  • QDs consist of an inorganic heavy metal core and shell which emit within the NIR spectrum. This structure is then surrounded by a hydrophilic organic coating which facilitates aqeuous solubility and lymphatic distrubtion. QDs have been extensively studied and are ideal for SLN mapping as their hydrodynamic diameter can be customized to the appropriate size within a narrow distribution (15–20 nm), they can be engineered to have an anionic surface charge, and exhibit an extremely high SBRs with significant photostability. Unfortunately, safety concerns due to the presence of heavy metals within the QDs so far have precluded clinical application

Human Clinical Trials and NIR SLN mapping

Several studies have investigated the clinical use of indocyanine green without adsorption to HSA for NIR fluorescence-guided SLN mapping in breast and gastric cancer with good success (9-13).

Kitai et al. first examined this technique in 2005 in breast cancer patients, and was able to identify a SLN node in 17 of 18 patients using NIR fluorescence rather than the visible green color of ICG (9). Sevick-Muraca et al. reported similar results using significantly lower microdoses of ICG (10 – 100 μg), successfully identifying the SLN in 8 of 9 patients (11). Similar to these subcutaneous studies, 56 patients with gastric cancer underwent endoscopic ICG injection into the submucosa around the tumor 1 to 3 days preoperatively or injection directly into the subserosa intraoperatively with identification of the SLN in 54 patients (13).

Recently, Troyan et al. have completed a pilot phase I clinical trial examining the utility of NIR imaging the ICG:HSA nanoparticle fluorophore for SLN mapping/biopsy in breast cancer using the FLAREsystem. In this study, 6 patients received both 99mTc-sulfur colloid lymphoscintigraphy along with ICG:HSA at micromolar doses. SLNs were identified in all patients using both methods. In 4 of 6 patients the SLNs identified were the same, while in the remaining two, lymphoscintigraphy identified an additional node in one patient and ICG:HSA identified an additional SLN in the other. Irrespective, this study demonstrates that NIR SLN mapping with low dose ICG:HSA is a viable method for intraoperative SLN identification.

Nanotechnology and Drug Delivery in Lung cancer

We previously explored Lung cancer and nanotechnology aspects as polymer nanotechnology has been an area of significant research over the past decade as polymer nanoparticle drug delivery systems offer several advantages over traditional methods of chemotherapy delivery

see: (15) http://pharmaceuticalintelligence.com/2012/11/08/lung-cancer-nsclc-drug-administration-and-nanotechnology/                (16) http://pharmaceuticalintelligence.com/2012/12/01/diagnosing-lung-cancer-in-exhaled-breath-using-gold-nanoparticles/

As the importance of micrometastatic lymphatic spread of tumor becomes clearer, there has been much interest in the use of nanoparticles for lymphatic drug delivery. The considerable focus on developing an effective method for SLN mapping for lung cancer is indicative of the importance of nodal spread on overall survival.

Our lab is investigating the use of image-guided nanoparticles engineered for lymphatic drug delivery. We have previously described the synthesis of novel, pH-responsive methacrylate nanoparticle systems (14). Following a simple subcutaneous injection of NIR fluorophore-labeled nanoparticles 70 nm in size, we have shown that we can deliver paclitaxel loaded within the particles to regional draining lymph nodes in several organ systems of Yorkshire pigs while simultaneously confirming nodal migration using NIR fluorescent light. Future studies will need to investigate the ability of nanoparticles to treat and prevent nodal metastases in animal cancer models. Additionally, the development of tumor specific nanoparticles will potentially allow for targeting of chemotherapy to small groups of metastatic tumor cells further limiting systemic toxicities by narrowing the delivery of cytotoxic drugs.

Ref:

1. http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/pdf/nrc3180.pdf

2. http://www.nature.com/nrc/focus/metastasis/index.html

3. http://www.cancer.gov/cancertopics/factsheet/Sites-Types/metastatic

4. http://www.cancerresearchuk.org/cancer-help/about-cancer/what-is-cancer/body/the-lymphatic-system

5. http://www.macmillan.org.uk/Cancerinformation/Cancertypes/Lymphnodessecondary/Secondarycancerlymphnodes.aspx

6. Khullar O, Frangioni JV and Colson YL. Image-Guided Sentinel Lymph Node Mapping and Nanotechnology-Based Nodal Treatment in Lung Cancer using Invisible Near-Infrared Fluorescent Light. Semi Thorac Cardiovasc Surg 2009 :21 (4);  309-315. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109504/

7. Stacker SA, Achen MG, Jussila L,  Baldwin ME and Alitalo K. Metastasis: Lymphangiogenesis and cancer metastasis.  Nature Reviews Cancer 2002 2, 573-583. http://www.nature.com/nrc/journal/v2/n8/full/nrc863.html

8. Schroeder A., Heller DA., Winslow MM., Dahlman JE., Pratt GW., Langer R., Jacks T and Anderson DG.. Nature Reviews Cancer 2012; 12(1), 39-50. Treating metastatic cancer with nanotechnology. http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/pdf/nrc3180.pdf

http://www.nature.com.rproxy.tau.ac.il/nrc/journal/v12/n1/full/nrc3180.html

9. Kitai T, Inomoto T, Miwa M, et al. Fluorescence navigation with indocyanine green for detecting sentinel lymph nodes in breast cancer. Breast Cancer. 2005;12:211–215.

10. Ogasawara Y, Ikeda H, Takahashi M, et al. Evaluation of breast lymphatic pathways with indocyanine green fluorescence imaging in patients with breast cancer. World journal of surgery.2008;32:1924–1929.

11. Sevick-Muraca EM, Sharma R, Rasmussen JC, et al. Imaging of lymph flow in breast cancer patients after microdose administration of a near-infrared fluorophore: feasibility study. Radiology.2008;246:734–741.

12. Miyashiro I, Miyoshi N, Hiratsuka M, et al. Detection of sentinel node in gastric cancer surgery by indocyanine green fluorescence imaging: comparison with infrared imaging. Ann Surg Oncol.2008;15:1640–1643.

13. Tajima Y, Yamazaki K, Masuda Y, et al. Sentinel node mapping guided by indocyanine green fluorescence imaging in gastric cancer. Ann Surg. 2009;249:58–62.

14. Griset AP, Walpole J, Liu R, et al. Expansile nanoparticles: synthesis, characterization, and in vivo efficacy of an acid-responsive drug delivery system. J Am Chem Soc. 2009;131:2469–2471

15. http://pharmaceuticalintelligence.com/2012/11/08/lung-cancer-nsclc-drug-administration-and-nanotechnology/

16.  http://pharmaceuticalintelligence.com/2012/12/01/diagnosing-lung-cancer-in-exhaled-breath-using-gold-nanoparticles/

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Nitric Oxide and it’s impact on Cardiothoracic Surgery

Author, curator: Tilda Barliya PhD

 

In the past few weeks we’ve had extensive in-depth series about nitric oxide (NO) and it’s role in renal function and donors in renal disorders, coagulation, endothelium and hemostasis. This inspired this new post regarding the impact of NO on cardiothoratic surgery.  You can read and follow up on these posts here: http://pharmaceuticalintelligence.com/category/nitric-oxide-in-health-and-disease/

Atherosclerosis in the form of peripheral arterial disease (PAD) affects approximately eight million Americans, which includes 12 to 20% of individuals over the age of 65.  Approximately 20% of patients with PAD have typical symptoms of lower extremity claudication, rest pain, ulceration, or gangrene, and one-third have atypical exertional symptoms. Persons with PAD have impaired function and quality of life even if they do not report symptoms and experience a decline in lower extremity function over time. Cardiovascular disease is the major cause of death in patients with intermittent claudication; the annual rate of cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes) is 5 to 7%.  Thus, PAD represents a significant source of morbidity and mortality. (1) (http://www.medscape.com/viewarticle/569812).

Several options exist for treating atherosclerotic lesions, including:

  • percutaneous transluminal angioplasty with and without stenting,
  • endarterectomy
  • bypass grafting

Unfortunately, patency rates for each of these procedures continue to be suboptimal secondary to the development of neointimal hyperplasia. A universal feature of all vascular surgical procedures is the removal of or damage to the endothelial cell monolayer that occurs whether the procedure performed is endovascular or open. This endothelial damage leads to a decreased or absent production of nitric oxide (NO) at the site of injury.

noendoschematic

he relationship between NO and the cardiovascular system has proven to be a landmark discovery, and the scientists credited for its discovery were awarded the Nobel Prize in Medicine in 1998. Since its discovery, NO has proven to be one of the most important molecules in vascular homeostasis. In fact, the term endothelial dysfunction has now become synonymous with the reduced biologic activity of NO.

NO produced by endothelial cells has been shown to have many beneficial effects on the vasculature.

As described above,

  • NO stimulates vascular smooth muscle cells (VSMC) relaxation, which leads to vessel vasodilatation.  
  • NO has opposite beneficial affects on endothelial cells compared with VSMCs.
  • Whereas NO stimulates endothelial cell proliferation and prevents endothelial cell apoptosis,  it inhibits VSMC growth and migration  and stimulates VSMC apoptosis.  
  • NO also has many thromboresistant properties, such as inhibition of platelet aggregation, adhesion, and activation;  inhibition of leukocyte adhesion and migration;  and inhibition of matrix formation

 As stated before, the endothelial cell monolayer is often removed or damaged during the time of vascular procedures, which leads to a local decrease in the production of NO. It is now understood that this loss of local NO synthesis by endothelial cells at the site of vascular injury is one of the inciting events that allows platelet aggregation, inflammatory cell infiltration, and VSMC proliferation and migration to occur in excess, which, taken together, leads to neointimal hyperplasia.

Reendothelialization of the injured artery can restore proper function to the artery and potentially halt the restenotic process. Many studies have attempted to improve the patency of bypass grafts and stents by coating them with endothelial cells in the hope that this would restore the thromboresistant nature of native blood vessels.

Unfortunately, although it has been possible to coat these devices with endothelial cells, these cells do not behave like normal endothelial cells and their NO production is often diminished or absent. Because the vasoprotective properties of endothelial cells are largely carried out by NO alone, investigators are engaged in research to improve the bioavailability of NO at the site of vascular injury in an attempt to reduce the risk of thrombosis and restenosis after successful revascularization. The overall goal of using a NO-based approach is to reproduce the same thromboresistive moiety observed with normal NO production.

Why of delivering NO to the injured site:

  • Systemic delivery
  • Local delivery

Systemic Delivery

One simple mechanism by which to deliver NO to the body is via inhalational therapy. Inhaled NO has been used clinically in the past to selectively reduce pulmonary vascular resistance in patients with pulmonary hypertension, as well as a potential therapy for patients with acute respiratory distress syndrome. Because the gas is delivered only to the pulmonary system and has a very short half-life, it was thought that there would be no systemic effects of the drug. Subsequently, studies in the mid- to late 1990s suggested that inhaled NO had beneficial antiplatelet and antileukocyte properties without adverse systemic side effects (2,3)

To test if inhaled NO had any beneficial systemic properties specifically on the vasculature, Lee and colleagues evaluated the effect of inhaled NO on neointimal hyperplasia in rats undergoing carotid balloon injury, Unfortunately, the treatment was required for the full 2 weeks to see any difference between the treatment and the control group, thereby limiting its clinical utility.

Despite some of the early animal studies, investigations with healthy human volunteers failed to reproduce these findings.I t was speculated that despite the obvious effects of inhaled NO on the pulmonary vasculature, systemic bioavailability could not be reliably achieved because of the immediate binding and depletion of NO by hemoglobin as soon as it entered the systemic circulation.

Hamon and colleagues tested the ability of orally supplementing l-arginine (2.25%), the precursor to NO, in the drinking water of rabbits to reduce the formation of neointimal hyperplasia after injuring the iliac arteries with a balloon.  This amount of l-arginine is approximately sixfold higher than normal daily intake. When the arteries were studied 4 weeks after injury, the l-arginine-fed group exhibited less neointimal hyperplasia and greater acetylcholine-induced relaxation compared with the control animals. The authors speculated that the improved outcomes were due to increased bioavailability of NO secondary to the l-arginine-supplemented diets. To test the ability of this supplemented diet to reduce neointimal hyperplasia in a vein bypass graft model, Davies and colleagues fed rabbits l-arginine (2.25%) 7 days prior to and 28 days after common carotid vein bypass grafts. A 51% decrease in the formation of neointimal hyperplasia was demonstrated in the l-arginine-fed groups, and their vein grafts exhibited preserved NO-mediated relaxation.

Despite some of the positive findings in animals, similar studies in humans have failed to show any benefit with l-arginine supplementation. Shiraki and colleagues studied the effects of short-term high-dose l-arginine on restenosis after PTCA.  Thirty-four patients undergoing cardiac catheterization and PTCA for angina pectoris received 500 mg of l-arginine administered through the cardiac catheter immediately prior to PTCA and 30 g per day of l-arginine administered via the peripheral vein for 5 days after PTCA. No significant statistical differences in restenosis were observed between the two groups (34% vs 44%). The authors speculated that the lack of effect was secondary to the fact that although the levels of l-arginine in the plasma increased significantly, NO and cyclic guanosine monophosphate (cGMP) did not. (4)

Table 1.  Comparison of Different Nitric Oxide Donor Drugs Currently Used for Clinical or Research Purposes
Drug Mechanism of NO Release Unique Properties
Diazeniumdiolates Spontaneous when in contact with physiologic fluidsNO release follows first-order kinetics Stable as solidsVarious reliable half-lives depending on the structure of the nucleophile it is attached to
Nitrosamines can form as by-products
S-Nitrosothiols Copper ion-mediated decomposition Stable as a solid
Direct reaction with ascorbate Must be protected from light
Homeolytic cleavage by light Present in circulating blood
Potential for unlimited NO release
Sydnonimines Requires enzymatic cleavage by liver esterases to form active metabolite Stable as a solidMust be protected from light
Requires molecular oxygen as an electron acceptor Requires alkaline pHReleases superoxide as a by-product, which may have negative effects
l-Arginine Substrate for NOS genes Stable as a solid
Ease of administration
Dependent on presence of NOS for NO production
Sodium nitroprusside Requires a one-electron reduction to release NO Stable as a solid
Must be protected from light
Light can induce NO release Must be given intravenously
Releases cyanide as a by-product
Organic nitrates Either by enzymatic cleavage or nonenzymatic bioactivation with sulfhydryl or thiol groups Stable as a solid
Must be protected from light
Ease of administration
Development of tolerance limits efficacy
NO-releasing aspirin Require enzymatic cleavage to break the covalent bond between the aspirin and the NO moiety Stable as a solid
Ease of administration
Inherent benefits of aspirin also
Does not affect systemic blood pressure

Despite the ease of administration, the reliability of drug delivery, and the relative safety of these NO-donating drugs, there are limitations associated with systemic administration. One such limitation is that NO is rapidly inactivated by hemoglobin in the circulating blood, resulting in limited bioavailability. Furthermore, in attempts to increase the amount of drug delivered to obtain the desired clinical effect, unwanted systemic circulatory effects (eg, vasodilation) and unwanted hemostatic effects (eg, bleeding) often preclude administration of biologically effective doses of NO.

Because NO produces systemic side effects, lower doses of NO have been used in many of the human studies. One of the reasons for the differences observed between the animal studies and the human studies was the 10- to 50-fold lower doses of drugs used in the human studies compared with the animal studies. Thus, local delivery of NO may achieve improved results.

Local Delivery

The local delivery of drugs allows for the administration of the maximally effective dose of a drug without the unwanted systemic side effects. Because the target vessels are easily accessible during most vascular procedures, a local pharmacologic approach to administer a drug during the intervention can be easily performed.

Suzuki and colleagues performed a prospective, randomized, single-center clinical trial. (7)

The study population consisted of patients with symptomatic ischemic heart disease who were undergoing coronary artery stent placement. After stent deployment, l-arginine (600 mg/6 mL) or saline (6 mL) was locally delivered via a catheter over 15 minutes. The patients were followed with serial angiography and intravascular ultrasonography to assess for neointimal thickness for up to 6 months. The authors found that in the l-arginine-treated groups, there was slightly less neointimal volume, but this was not statistically significant.

Because it was not known if the addition of l-arginine actually translated to increased NO production, several studies have focused on the addition of NO donors directly to the site of injury.However, Critics of some of the highlighted animal studies point out that the evaluation of neointimal hyperplasia was performed radiographically, which could be subjectively biased. Furthermore, infusing the drug through a catheter for an extended period of time during the procedure to achieve an effect is not clinically feasible. Because of this, other studies have aimed to develop a clinically applicable approach to deliver NO locally to the site of injury.

  • Hydrogels
  • Vascular grafts
  • Gene therapy

represents another method by which to locally increase the level of NO at the site of vascular injury, tested in different multiple creative animal models. Thought, most of this studies shown great preliminary results, only the gene therapy moved forward into randomized clinical trial in humans using gene therapy to reduce neointimal hyperplasia.

In December 2000, the Recombinant DNA Advisory Committee at the National Institutes of Health voted unanimously to proceed with the first phase of clinical evaluation of iNOS lipoplex-mediated gene transfer, called REGENT-1: Restenosis Gene Therapy Trial. (8). The primary objective of this multicenter, prospective, single-blind, dose escalation study was to obtain safety and tolerability information of iNOS-lipoplex gene therapy for reducing restenosis following coronary angioplasty. As of 2002, 27 patients had been enrolled overseas and the process had been determined to be safe. To date, no results have been published as it appears that this trial lost its funding and closed. On April 5, 2002, a notification was issued that the trial had been closed without enrolling any individuals in the United States.

Unfortunately, despite the promising findings shown with NOS therapy, the field of gene therapy has been mottled by two widely known complications. One case occurred as the result of administering a large viral load that led to the death of a patient. In addition, in France, there were at least two cases of malignancy following retroviral gene therapy.  (9)

Summary

Atherosclerosis in the form of coronary artery disease and peripheral vascular disease continues to be a major source of morbidity and mortality. Unfortunately, the procedures and materials that are currently used to alleviate these disease states are temporary at best because of the inevitable injury to the native endothelium and the subsequent impairment of NO release. Since the discovery of NO and its role in vascular biology, a main focus in vascular research has been to create novel mechanisms to use NO to combat neointimal hyperplasia. To date, numerous animal studies have restored NO production to the vasculature and have shown that this inhibits neointimal hyperplasia, improves patency rates, and is safe to the animal. Clinical studies using these novel NO-releasing compounds in humans are on the horizon.

Ref:

1. Daniel A. Popowich, Vinit Varu, Melina R. Kibbe. Nitric Oxide: What a Vascular Surgeon Needs to Know. Vascular. 2007;15(6):324-335. (http://www.medscape.com/viewarticle/569812).

2.  Gries A, Bode C, Peter K, et al. Inhaled nitric oxide inhibits human platelet aggregation, P-selectin expression, and fibrinogen binding in vitro and in vivo Circulation 1998;97:1481-7.

3.  Lee JS, Adrie C, Jacob HJ, et al. Chronic inhalation of nitric oxide inhibits neointimal formation after balloon-induced arterial injury Circ Res 1996;78:337-42.

4.  Shiraki T, Takamura T, Kajiyama A, et al. Effect of short-term administration of high dose l-arginine on restenosis after percutaneous transluminal coronary angioplasty J Cardiol 2004;44:13-20.

5. David A. Fullerton, MD, Robert C. McIntyre, Jr, MD. Inhaled Nitric Oxide: Therapeutic Applications in Cardiothoracic Surgery. Ann Thorac Surg 1996;61:1856-1864. http://ats.ctsnetjournals.org/cgi/content/abstract/61/6/1856

6. Owen I.Miller,Swee Fong Tang, Anthony Keech,Nicholas B.Pigott, Elaine Beller and David S. Celemajer.  Inhaled nitric oxide and prevention of pulmonary hypertension after congenital heart surgery: a randomised double-blind study. The Lancet,2000:356; 9240 Pages 1464 – 1469,  http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(00)02869-5/abstract

7. Suzuki T, Hayase M, Hibi K, et al. Effect of local delivery of l-arginine on in-stent restenosis in humans Am J Cardiol 2002;89:363-7.

8. von der Leyen HE, Chew N. Nitric oxide synthase gene transfer and treatment of restenosis: from bench to bedside Eur J Clin Pharmacol 2006;62:83-89

9.  Barbato JE, Tzeng E. iNOS gene transfer for graft disease Trends Cardiovasc Med 2004;14:267-72.

10. E. Matevossian, A. Novotny, C. Knebel, T. Brill, M. Werner, I. Sinicina, M. Kriner, M. Stangl, S. Thorban, and N. Hüser. The Effect of Selective Inhibition of Inducible Nitric Oxide Synthase on Cytochrome P450 After Liver Transplantation in a Rat Model. Transplantation Proceedings 2008, 40, 983–985. http://211.144.68.84:9998/91keshi/Public/File/29/40-4/pdf/1-s2.0-S0041134508004181-main.pdf

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Reporter: Aviva Lev-Ari, PhD, RN

Demonstrate Biosimilarity with 100% confidence. Everytime

While offering greater flexibility, new FDA biosimilar guidelines lack specificity, nothing in the development can be taken for granted.

Develop biosimilars that exhibit comparability in every required category and avoid ever having a biosimilar application rejected. With so much at stake, are you 100% confident of demonstrating comparability every time? 

Demonstrate Biosimilarity is your opportunity to get first hand case studies from the leading biosimilar and generic drug developers as well as the FDA on the best approaches to…

  1. Interpret regulatory ambiguity and determine how much similarity must be demonstrated to gain approval and achieve interchangeability
  2. Ensure stability and analytical comparability as well as comparability in safety and PK/PD by optimizing your quality assessment strategy
  3. Reduce the impact of immunogenicity in your biosimilar drug and discover how to translate this regulatory expectation into a clinical trial concept
  4. Optimize your approaches to protein characterization with practical guidance from industry leading analytical scientists and service providers

Demonstrate Biosimilarity will tackle burning issues surrounding naming and pricing policiesoriginators defence strategiesmanufacturing challenges andhow to identify the best target for biosimilar development. Achieve technical insights and obtain cutting edge intelligence from 16 pharma case studies showcasing biosimilar best practise.

Attend and gain first hand testimony from the FDA, that combined with this depth of insight will give you the information you need to move quickly and decisively to get your biosimilar approved.

What you will learn? 

Attend Demonstrate Biosimilarity to:

  • Learn how to effectively monitor the higher-order structure and associated structural dynamics of your biosimilar drug molecules by optimizing your approach to comparability studies with practical guidance from Biogen Idec
  •  Expand your knowledge of how protein aggregates interact with the immune system and how this understanding can be used to reduce immunogenicitywith the Chief Medical Research Officer at the FDA
  •  More effectively determine the extent of physiochemical, pre-clinical and clinical characterization required to demonstrate biosimilarity and gain approval with case studies from Novartis and Sandoz
  • Enhance harmonization of your biosimilar data with a comprehensive comparison of the EMEA Vs USA regulatory landscape with Sandoz, Pfizerand Wokhardt
  • Get insight from MedImmune to achieve comparability when test methods are changed during the product life cycle and a non-inferior, equivalent, or superior replacement study model has been selected
  • Understand fully the applications of bioassays to determine product potency, aid biological characterization, test comparability, and determine stability with expert advice and clinical data from Teva Pharmaceuticals
  • Get a first hand guide from the FDA regarding quantitation and characterization of protein aggregates in biosimilars to ensure quality and safety of products,consistency of manufacture between lots and comparability when the manufacturing process has been changed

Does the FDA biosimilar guidance go far enough? Not if you want to operate with 100% confidence.

In fact the FDA still wants to take a cautious case by case approach. Complex biosimilar comparability studies are inherently risky and the consequences of a rejected submission are dramatic. This means that an open dialogue with FDA & other developers is essential.

Our recent industry survey highlighted two key desires for drug developers:

 

To know exactly how other drug developers are tackling challenges such as structural comparability, immunogenicity and interchangeability

What the FDA is currently thinking and how this would apply to their development programs

In response to this demand for insight and support we’ve assembled the FDA alongside the industry’s best at Demonstrate Biosimilarity Washington DC (13-14th February).

 

Learn from the testimony of 18 industry speakers including Sandoz, Teva, Wokhardt, GSK, Pfizer, MedImmune, Biogen Idec, Amgen, Novartis, Merck and senior FDA representatives dedicated to answering these questions.  This will ensure that you can effectively achieve comparability , demonstrate biosimilarity and avoid costly failed submissions. View the agenda now.

Overcome challenges such as:

 

  • How do I assess the level of biological purity needed to match my innovator product and avoid making several submission to regulators?
  • Is it truly possible to achieve interchangeability and how can I convince patients and physicians of the equivalence of my biosimilar and ensure market access?
  • What are the best practises to decrease immunogenicity risk to increase my chances of achieving comparability?
  • Where can I obtain a suitable reference product to allow me to begin characterization?
  • What is the FDA’s current thinking on the criteria for analytical, stability, safety and PK/PD comparability?

Download the brochure now to view the full agenda, workshops & speaker line up.

http://demonstrate-biosimilarity.com/download-brochure?utm_campaign=2924FIERCE&utm_medium=email&utm_source=Eloqua&elq=268b14bad28e4a9f979fc60b45a9c3c6&elqCampaignId= 

This meeting will provide you with unrivalled access to 15 case study lead presentations from pioneering biosimilar and generic drug developers sharing their innovative new approaches.

Learn how your peers are decreasing the clinical work required, minimising the impact of immunogenicity, achieving interchangeability and how they define targets for biosimilar development.

If that isn’t enough, the FDA will be giving keynote presentations on the regulatory expectations regarding aggregates and comparability as well as minimizing the impact of immunogenicity by understanding the role of protein aggregates in unwanted immunogenicity.

SPEAKERS

http://demonstrate-biosimilarity.com/speakers?utm_campaign=2924FIERCE&utm_medium=email&utm_source=Eloqua&elq=268b14bad28e4a9f979fc60b45a9c3c6&elqCampaignId=

AGENDA:

Day One

13th February, 2013

8.00 Registration

8.55 Chair’s Opening Remarks 

Optimizing Quality Assessments: Biochemical and Physiochemical Properties

9.00 Regulatory Expectations Regarding Aggregates and Comparability

• A guide from the FDA regarding quantitation and characterization of protein aggregates to ensure quality and safety, consistency of manufacture and comparability when the manufacturing process is being changed

• Overcoming challenges associated with characterization of the aggregates’ full size range to maximize safety information

Ewa Marszal, Chemist, Laboratory of Plasma Derivatives, Division of Haematology, CBER, FDA

9.30 An Industry Perspective: Optimizing Approaches to Protein Characterization in the Development of Biosimilars

• Practical guidance for optimizing analytical characterization of commercial products

• Understanding the innovation required in both technical development and clinical development

• Devising a systematic engineering approach to match biosimilar to reference product

Roxana Butoi, Manager, Biosimilars, GSK

10.00 Solution Spotlight: Analytical methods for monitoring biosimilar glycosylation

Scott Barksdale, Director, Business Development, Procognia

10.15 Speed Networking & Morning Refreshments

11.45 CASE STUDY: Implementing Advanced Analytical Methods and Regulatory Approved Comparability Strategies

• Numerous case studies demonstrating when test methods are changed during the product life cycle and a non-inferior, equivalent, or superior replacement study model has been selected based on the intended use of the new test method

• How to set risk-based acceptance criteria from product specifications and existing manufacturing process knowledge

Stephan Krause, PDA Task Force Leader for Analytical Methods, and Principal Scientist, Analytical Biochemistry, MedImmune

12.15 Application of Hydrogen/Deuterium Exchange with Mass Spec Detection (H/DX-MS) to Assess Comparability 

• Applications of instrumental hardware and computer software to enable H/DX-MS to be employed in a practical and routine way to assess biosimilarity

• Optimizing comparability studies to monitor the higherorder structure and associated dynamics of biosimilar drugs

Steven Berkowitz, Principal Investigator, Analytical Development, Biogen Idec

12.45 Effective use of Bioassays to Streamline Biosimilar Development 

• Applications of bioassays to determine product potency, aid biological characterization, and test comparability

• Bioassays as a bioanalytical tool in support of pre clinical and clinical studies throughout the span of biosimilar development

• Developing an assay strategy and clear understanding of regulatory expectations, development and implementation of validated biological assays to ensure approval

Patrick Liu, Senior Director and Global Head of Bioassays, Teva Pharmaceuticals

1:15 Lunch & Networking

2.15 CASE STUDY: Correcting Biases in Light Obscuration and Light Scattering Measurements of Protein Particles 

• A demonstration of the applications of optical models for measuring of protein particles

• Several case studies involving protein aggregates, examining size errors and the practicality of corrections for biosimilar development

Dean Ripple, Leader, Bioprocess Measurements Group, National Institute of Standards and Technology

Demonstrating Biosimilarity: Biochemical and Physiochemical Properties

Roxana Butoi, Manager, Biosimilars, GSK 

Stephan KrausePDA Task Force Leader for Analytical Methods, and Principal Scientist, Analytical Biochemistry, MedImmune

Steven Berkowitz, Principal Investigator, Analytical Development, Biogen Idec

Patrick Liu, Senior Director and Global Head of Bioassays, Teva Pharmaceuticals

3.15 Afternoon Refreshments & Networking  

Achieving Interchangeability with a Biosimilar Product

3.45 Application of Biophysical Techniques in Comparability Exercises: Quantitative Assessment of Spectral Similarity

• Effective use of biophysical tools, including circular dichroism spectroscopy to provide qualitative assessment of the similarity in higher order structure for biological molecules

• Using statistical analysis to provide a more quantitative evaluation of spectral similarity

Qin Zou, Senior Principal Scientist, BioProcess Analytics, Pfizer  

4.15 The Momenta Approach to Developing Biosimilars and Potentially Interchangeable Biologics

• Establishing biosimilarity and potential interchangeability by focussing on “comparison” between RPP and biosimilar

• An overview of Momenta’s key takeaways from the recently issued FDA draft guidance

Jim Roach, SVP, Development and Chief Medical Officer, Momenta Pharmaceuticals

4.45 Comparability and Biosimilarity – Two Sides of the Same (or a Different) Coin? 

• Compare and contrast the comparability and biosimilarity paradigms, with consideration for the impact of Quality by Design on these product development strategies

• The challenges and future directions of product characterization for biosimilars

Brent Kendrick, Director of Analytical Sciences, Amgen

5.15 Chair’s Closing Remark

 

Day Two

14th February, 2013

8.15 Registration

9.10 Chair’s opening remarks

9.15 Analysis of the Biosimilar Development Pipeline

• Gain a better understanding of how the biosimilar market will develop and evolve in light of the biosimilarity guidelines

• Understand when products will begin entering the U.S. and European markets

• What different development approaches are companies taking?

• What will be the involvement of companies in the US/EU

vs. those in developing countries?

Ronald Rader, President, Biotechnology Information Institute

9.45 Minimizing the Impact of Immunogenicity Understanding the Role of Protein Aggregates in Unwanted Immunogenicity

• How subvisible protein aggregates may interact with the immune system, their potential impact on product safety and efficacy

• An FDA perspective on the current regulatory considerations pertaining to the control of these particulates

Jack Ragheb, Chief Medical Research Officer, CDER, FDA

10.15 Morning Refreshments & Networking

Navigating the Regulatory and Legal Environment for Biosimilars

11.00 Comparison of the EMEA and USA Regulation for Biosimilar Development

• A review of the current state of initiatives for biosimilars in both EMEA and USA

• Perspective on how regulatory uncertainty could be reduced in the implementation of quality by design arguments

• A comprehensive comparison of the EMEA Vs USA landscape an the intricacies of harmonization

Ajaz Hussain, Chief Scientific Officer, Workhardt

11.30 An Industry Perspective: USA Current and Future Regulatory Setting for Biosimilars 

• Understanding the need to maximize productivity of FDA biosimilars development meetings

• Identifying and justifying differences between structural and functional characterization

• Negotiating regulatory landscape for clinical development and determining the required magnitude of the program

• Pursuing interchangeability for your biosimilar product without FDA guidance

John Pakulski, Senior Director and Head US Biopharmaceutical Regulatory Affairs, Sandoz

12.00 Biosimilar Regulation Roundtable Session 

• An opportunity for delegates to discuss with the regulators and regulatory experts the recent FDA biosimilar guidelines

• Collaboratively discuss the impact of the regulation and strategies to comply with it

12.45 Lunch & Networking

2.00 A Practical Guide and Overview of Current Strategies of Biocomparability and Biosimilarity 

• Industry perspective on the current guidance from EMEA and FDA for biocomparability

• Current strategies to assess the the extent of physiochemical, pre-clinical and clinical characterization based on the stage of development

• Emerging guidance on biosimilarity and the implications on the pre-clinical and clinical development programs for biosimilars

• Use of biomarkers in the biocomparability exercise: Are we there yet?

Shefali Kakar, Senior Fellow, Clinical Pharmacology, Oncology Business Unit, Novartis

2.30 Understand the Nuances and Implications of the FDA Guidelines on Biosimilars

• A detailed examination of the content of the recently released FDA guidelines and how to best understand the requirements for quantity of data, sources of material and types of studies permitted

• What kind of potential exists for increased efficiency, collaboration and cost-effectiveness in the U.S?

• The repercussions of important FDA decisions that have been made regarding user fees to be paid by companies in order to submit an application for a biosimilar

Helen Hartman, Regulatory Affairs Strategist, Pfizer

3.00 Afternoon Refreshments & Networking

Optimizing Approaches for Biosimilar Production and Manufacture

3.30 CASE STUDY: Evaluation of Comparability due to Changes in Scale-up, Process, Manufacturing Site, and Formulation 

• A case study of a preliminary comparability study used to evaluate the changes due to scale-up, manufacturing site, process and formulation of batches used in phases I/II and III

• A detailed overview of the extended characterization results from this study

• Preliminary assessment of comparability studies to establish the type of analytical testing required to correlate manufacturing changes to the product characteristics in the final comparability testing

Soundara Soundararajan, Principal Scientist, Bioprocess Development, Merck

4.00 Biosimilars: The Age of Post-Patent Medicine

• How will the thorny issues of safety, efficacy and cost (and in that order) impact the role of biosimilars in 21st century healthcare

• A detailed look at the challenges associated with demonstrating biosimilarity to the relevant regulatory bodies

Peter Pitts, President, Center for Medicine in the Public Interest

4.30 Chair’s Closing Remarks

 

Workshops

Pre Conference Workshops: 12th February 2013

Workshop A) 08.00 – 11.00: Measurement, Characterization and Impactof Impurities for Biosimilars

Biotechnology and biosimilar products have substantial differences fromchemical entities in their starting materials, manufacturing processes, productcharacteristics, stability profiles, and interactions with containers and closures.Each of these can impact the nature of the impurities present in the finalproduct.

This workshop will provide an overview of these differences with links tothe current regulatory expectations and notes on current ‘best practices’for impurities assessment during development.

  • Impurities in Biotechnology/Biosimilar Products – What Makes themCritical?

– What are the specific guidance requirements for biosimilar productimpurities?

– What elements impact meaningful, reliable specifications for processand product impurities?

– How are the risks of impurities managed during development?

  • Example of Critical Process-Related Impurities: Host Cell Proteins

– What are the key requirements for measuring host cell proteins fromvarious expression systems?

– How should host cell protein assays be selected, optimized, and validated?

  • Example of Critical Product-Related Impurities: Particulates

– What types of particulates are of concern?

– How do we measure particulates?

  • Example of Critical Container/Closure Related Impurities: Extractables/Leachables

– How do we identify the extractables and leachables?

– How can extractables or leachables affect the product?

You will leave this workshop with a detailed understanding of the impact of key impurities in biosimilar development, through case study examples ofeach, to review the current and emerging issues for biotechnology productsassociated with each.

Led By: Nadine Ritter, Senior CMC Consultant, Biologics Consulting Group

 

Workshop B) 12.00 – 15.00: Strategies for an Abbreviated Clinical Programfor Biosimilar mAbs

This workshop is designed to give you a practical guide to develop theoptimum clinical strategy for developing a biosimilar to minimize the size ofthe clinical program require to demonstrate biosimilarityIn this workshop you will:

  • Understand how to design an abbreviated clinical program for biosimilardrugs
  • Learn to optimize phase I by developing a streamlined FIM PK study usingreference product and PK equivalence as endpoints
  • Discuss best practices for phase III dose and time response design
  • Develop solutions to challenges associated with safety, immunogenicity, interchangeability and extrapolation across multiple indications

You will leave this workshop with a step by step guide to taking a biosimilarthrough clinical development that will minimize the amount of clinical workrequired without compromising the quality or quantity of clinical evidence.

Led by: Partha Roy, Principle Consultant, PAREXEL Consulting

Please note that workshop B runs at the same time as workshop C – so you cannot attend both.

Workshop C) 12.00 – 15.00: Biosimilars: Is the Risk worth the Reward?

This workshop will demonstrate how you can capitalize on the recentregulatory developments, and offer all of the information you need tomove quickly and decisively to turn the streamlined biosimilars processinto a lucrative commercial opportunity.In this workshop you will:

  • Gain an understanding of the potential of the biosimilar market andassess the potential entry routes available for your business
  • Get an overview via numerous case studies of the latest progress inthe biosimilar field and discover how you can capitalize on the latestdevelopments
  • Understand the complex issue of biosimilar ROI and discusspractical strategies to maximize your return
  • Hear both provider and payer perspectives to gain a betterunderstanding of how you can cater to both of their needs

You will leave this workshop with all the information you need todevelop an effective commercially viable biosimilar development strategy.

Led by: James Harris, Chief Executive Officer, Healthcare Economics LLC

Please note that workshop B runs at the same time as workshop C – so you cannot attend both.

 

Workshop D) 15.30 – 18.30: Gain a Biosimilar Market Overview:Present and Future Challenges

Biosimilars present a new set of challenges for regulatory authoritieswhen compared with conventional generics. After many years in theslow lane, changes are driving new momentum in the market forbiosimilarsIn this workshop you will:

  • Analyze with industry leaders the present and future actions of themain players in biosimilar market in different regions of the world tohelp identify best practises from varying geo-specific approaches
  • Get an understanding of the patents used for the first generation ofapproved biopharmaceuticals and discover how to capitalize onpatents about to expire to open up new opportunities in the biosimilarmarket
  • Understand the critical issues for healthcare professionals surroundingthe use of biosimilars to make informed treatment decisions

You will leave this workshop with a greater understanding of thebiosimilar market place and an actionable biosimilar strategyincorporating the best practises discussed during this case study anddiscussion lead workshop.

Led by: Leandro Mieravilla, Global Market Manager mAbs, Cassara Biotech

 

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Telling NO to Cardiac Risk

DDAH Says NO to ADMA(1); The DDAH/ADMA/NOS Pathway(2)

Author-Writer-Reporter:  Stephen J. Williams, PhD

Endothelium-derived nitric oxide (NO) has been shown to be vasoprotective.  Nitric oxide enhances endothelial cell survival, inhibits excessive proliferation of vascular smooth muscle cells, regulates vascular smooth muscle tone, and prevents platelets from sticking to the endothelial wall.  Together with evidence from preclinical and human studies, it is clear that impairment of the NOS pathway increases risk of cardiovascular disease (3-5).

This post contains two articles on the physiological regulation of nitric oxide (NO) by an endogenous NO synthase inhibitor asymmetrical dimethylarginine (ADMA) and ADMA metabolism by the enzyme DDAH(1,2).  Previous posts on nitric oxide, referenced at the bottom of the page, provides excellent background and further insight for this posting. In summary plasma ADMA levels are elevated in patients with cardiovascular disease and several large studies have shown that plasma ADMA is an independent biomarker for cardiovascular-related morbidity and mortality(6-8).

admacardiacrisk

admaeffects

Figure 1 A. Cardiac risks of ADMA B. Effects of ADMA (Photo credit: Wikipedia)

ADMA Production and Metabolism

Nuclear proteins such as histones can be methylated on arginine residues by protein-arginine methyltransferases, enzymes which use S-adenosylmethionine as methyl groups.  This methylation event is thought to regulate protein function, much in the way of protein acetylation and phosphorylation (9).  And much like phosphorylation, these modifications are reversible through methylesterases.   The proteolysis of these arginine-methyl modifications lead to the liberation of free guanidine-methylated arginine residues such as L-NMMA, asymmetric dimethylarginine (ADMA) and symmetrical methylarginine (SDMA).

The first two, L-NMMA and ADMA, have been shown to inhibit the activity of the endothelial NOS.  This protein turnover is substantial: for instance the authors note that each day 40% of constitutive protein in adult liver is newly synthesized protein. And in several diseases, such as muscular dystrophy, ischemic heart disease, and diabetes, it has been known since the 1970’s that protein catabolism rates are very high, with corresponding increased urinary excretion of ADMA(10-13).  Methylarginines are excreted in the urine by cationic transport.  However, the majority of ADMA and L-NMMA are degraded within the cell by dimethylaminohydrolase (DDAH), first cloned and purified in rat(14).

endogenous NO inhibitors from pubchem

Figure 2.  Endogenous inhibitors of NO synthase.  Chemical structures generated from PubChem.

DDAH

DDAH specifically hydrolyzes ADMA and L-NMMA to yield citruline and demethylamine and usually shows co-localization with NOS. Pharmacologic inhibition of DDAH activity causes accumulation of ADMA and can reverse the NO-mediated bradykinin-induced relaxation of human saphenous vein.

Two isoforms have been found in human:

  • DDAH1 (found in brain and kidney and associated with nNOS) and
  • DDAH2 (highly expressed in heart, placenta, and kidney and associated with eNOS).

DDAH2 can be upregulated by all-trans retinoic acid (atRA can increase NO production).  Increased reactive oxygen species and possibly homocysteine, a risk factor for cardiovascular disease, can decrease DDAH activity(15,16).

  • The importance of DDAH activity can also be seen in transgenic mice which overexpress DDAH, exhibiting increased NO production, increased insulin sensitivity, and reduced vascular resistance  (17).  Likewise,
  • Transgenic mice, null for the DDAH1, showed increase in blood pressure, decreased NO production, and significant increase in tissue and plasma ADMA and L-NMMA.

amdanosfigure

Figure 3.  The DDAH/ADMA/NOS cycle. Figure adapted from Cooke and Ghebremarian (1).

As mentioned in the article by Cooke and Ghebremariam, the authors state: the weight of the evidence indicates that DDAH is a worthy therapeutic target. Agents that increase DDAH expression are known, and 1 of these, a farnesoid X receptor agonist, is in clinical trials

http://www.interceptpharma.com

An alternate approach is to

  • develop an allosteric activator of the enzyme.  Although
  • development of an allosteric activator is not a typical pharmaceutical approach, recent studies indicate that this may be achievable aim(18).

References:

1.            Cooke, J. P., and Ghebremariam, Y. T. : DDAH says NO to ADMA.(2011) Arteriosclerosis, thrombosis, and vascular biology 31, 1462-1464

2.            Tran, C. T., Leiper, J. M., and Vallance, P. : The DDAH/ADMA/NOS pathway.(2003) Atherosclerosis. Supplements 4, 33-40

3.            Niebauer, J., Maxwell, A. J., Lin, P. S., Wang, D., Tsao, P. S., and Cooke, J. P.: NOS inhibition accelerates atherogenesis: reversal by exercise. (2003) American journal of physiology. Heart and circulatory physiology 285, H535-540

4.            Miyazaki, H., Matsuoka, H., Cooke, J. P., Usui, M., Ueda, S., Okuda, S., and Imaizumi, T. : Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis.(1999) Circulation 99, 1141-1146

5.            Wilson, A. M., Shin, D. S., Weatherby, C., Harada, R. K., Ng, M. K., Nair, N., Kielstein, J., and Cooke, J. P. (2010): Asymmetric dimethylarginine correlates with measures of disease severity, major adverse cardiovascular events and all-cause mortality in patients with peripheral arterial disease. Vasc Med 15, 267-274

6.            Kielstein, J. T., Impraim, B., Simmel, S., Bode-Boger, S. M., Tsikas, D., Frolich, J. C., Hoeper, M. M., Haller, H., and Fliser, D. : Cardiovascular effects of systemic nitric oxide synthase inhibition with asymmetrical dimethylarginine in humans.(2004) Circulation 109, 172-177

7.            Kielstein, J. T., Donnerstag, F., Gasper, S., Menne, J., Kielstein, A., Martens-Lobenhoffer, J., Scalera, F., Cooke, J. P., Fliser, D., and Bode-Boger, S. M. : ADMA increases arterial stiffness and decreases cerebral blood flow in humans.(2006) Stroke; a journal of cerebral circulation 37, 2024-2029

8.            Mittermayer, F., Krzyzanowska, K., Exner, M., Mlekusch, W., Amighi, J., Sabeti, S., Minar, E., Muller, M., Wolzt, M., and Schillinger, M. : Asymmetric dimethylarginine predicts major adverse cardiovascular events in patients with advanced peripheral artery disease.(2006) Arteriosclerosis, thrombosis, and vascular biology 26, 2536-2540

9.            Kakimoto, Y., and Akazawa, S.: Isolation and identification of N-G,N-G- and N-G,N’-G-dimethyl-arginine, N-epsilon-mono-, di-, and trimethyllysine, and glucosylgalactosyl- and galactosyl-delta-hydroxylysine from human urine. (1970) The Journal of biological chemistry 245, 5751-5758

10.          Inoue, R., Miyake, M., Kanazawa, A., Sato, M., and Kakimoto, Y.: Decrease of 3-methylhistidine and increase of NG,NG-dimethylarginine in the urine of patients with muscular dystrophy. (1979) Metabolism: clinical and experimental 28, 801-804

11.          Millward, D. J.: Protein turnover in skeletal muscle. II. The effect of starvation and a protein-free diet on the synthesis and catabolism of skeletal muscle proteins in comparison to liver. (1970) Clinical science 39, 591-603

12.          Goldberg, A. L., and St John, A. C.: Intracellular protein degradation in mammalian and bacterial cells: Part 2. (1976) Annual review of biochemistry 45, 747-803

13.          Dice, J. F., and Walker, C. D.: Protein degradation in metabolic and nutritional disorders. (1979) Ciba Foundation symposium, 331-350

14.          Ogawa, T., Kimoto, M., and Sasaoka, K.: Purification and properties of a new enzyme, NG,NG-dimethylarginine dimethylaminohydrolase, from rat kidney. (1989) The Journal of biological chemistry 264, 10205-10209

15.          Ito, A., Tsao, P. S., Adimoolam, S., Kimoto, M., Ogawa, T., and Cooke, J. P.: Novel mechanism for endothelial dysfunction: dysregulation of dimethylarginine dimethylaminohydrolase. (1999) Circulation 99, 3092-3095

16.          Stuhlinger, M. C., Tsao, P. S., Her, J. H., Kimoto, M., Balint, R. F., and Cooke, J. P. : Homocysteine impairs the nitric oxide synthase pathway: role of asymmetric dimethylarginine.(2001) Circulation 104, 2569-2575

17.          Sydow, K., Mondon, C. E., Schrader, J., Konishi, H., and Cooke, J. P.: Dimethylarginine dimethylaminohydrolase overexpression enhances insulin sensitivity. (2008) Arteriosclerosis, thrombosis, and vascular biology 28, 692-697

18.          Zorn, J. A., and Wells, J. A.: Turning enzymes ON with small molecules. (2010) Nature chemical biology 6, 179-188

Other research papers on Nitric Oxide and Cardiac Risk  were published on this Scientific Web site as follows:

The Nitric Oxide and Renal is presented in FOUR parts:

Part I: The Amazing Structure and Adaptive Functioning of the Kidneys: Nitric Oxide

Part II: Nitric Oxide and iNOS have Key Roles in Kidney Diseases

Part III: The Molecular Biology of Renal Disorders: Nitric Oxide

Part IV: New Insights on Nitric Oxide donors

Cardiac Arrhythmias: A Risk for Extreme Performance Athletes

What is the role of plasma viscosity in hemostasis and vascular disease risk?

Cardiovascular Risk Inflammatory Marker: Risk Assessment for Coronary Heart Disease and Ischemic Stroke – Atherosclerosis.

Endothelial Dysfunction, Diminished Availability of cEPCs, Increasing CVD Risk for Macrovascular Disease – Therapeutic Potential of cEPCs

Biochemistry of the Coagulation Cascade and Platelet Aggregation – Part I

Nitric Oxide Function in Coagulation

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Personalized Medicine: Cancer Cell Biology and Minimally Invasive Surgery (MIS)

Curator: Aviva Lev-Ari, PhD, RN

 

 

In the field of Cancer Research, Translational Medicine  will become Personalized Medicine when each of the cancer type, below will have a Genetic Marker allowing the Clinical Team to use the marker for:

  • prediction of Patient’s reaction to Drug induction
  • design of Clinical Trials to validate drug efficacy on small subset of patients predicted to react favorable to drug regimen, increasing validity and reliability
  • Genetical identification of patients at no need to have a drug administered if non sensitivity to the drug has been predicted

Current urgent need exists for Identification of Genetic Markers to predict Patient’s reaction to Drugs Induction for the following types of Cancer:

The executive task of the clinician remains to assess the differentiation in Tumor Response to Treatment.

Review of limitations for the current existing Tools used by clinicians in to be found in:

Brücher BLDM, Bilchik A, Nissan A, Avital I & Stojadinovic A. Can tumor response to therapy be predicted, thereby improving the selection of patients for cancer treatment?  Future Oncology 2012; 8(8): 903-906 , DOI 10.2217/fon.12.78 (doi:10.2217/fon.12.78)   The heterogeneity is a problem that will take at least another decade to unravel because of the number of signaling pathways and the crosstalk that is specifically at issue.

Future Oncology August 2012, Vol. 8, No. 8, Pages 903-906 ,

It is suggested that the new modality should be based on individualized histopathology as well as tumor molecular, genetic and functional characteristics, and individual patients’ characteristics. The new modality should be based on empirical evidence that translates into relevant and meaningful clinical outcome data.

Cancer is in particular a difficult to treat tissue type pathology. In “Tumor response criteria: are they appropriate?” that concern is addressed as follows:

“This becomes a conundrum of sorts in an era of ‘minimally invasive treatment’. One frequently encountered example is that of a patient with chronic gastric reflux and an ultrasound-staged T3N1 distal esophageal adenocarcinoma, who had complete sonographic tumor response to neoadjuvant chemoradiation. The physician may declare that, the tumor having disappeared, the patient requires no further treatment. The surgical oncologist recommends resection, recognizing the fact that up to 20% or more of these complete responders will have identifiable nests of tumor beyond the mucosal scar within the specimen – in other words: residual tumor. In other cases, patients with clinical, sonographic, functional (PET) and histopathological ‘complete’ tumor response to induction therapy experience recurrence within the first 2 years of resection, reminding us of the intricacy and enigma of tumor biology. We have yet to develop the tools needed to consistently delineate the response of a tumor to multimodality therapy.”

This described reality in the Oncology Operating Room is coupled with new trends in invasive treatment of tumor resection.

Minimally Invasive Surgery (MIS) vs. conventional surgery dissection applied to cancer tissue with the known pathophysiology of recurrence and remission cycles has its short term advantages. However, in many cases MIS is not the right surgical decision, yet, it is applied for a corollary of patient-centered care considerations. At present, facing the unknown of the future behavior of the tumor as its response to therapeutics bearing uncertainty related to therapy outcomes.

An increase in the desirable outcomes of MIS as a modality of treatment, will be strongly assisted in the future, with anticipated progress to be made in the field of Cancer Research, Translational Medicine and Personalized Medicine, when each of the cancer types, above,  will already have a Genetic Marker allowing the Clinical Team to use the marker(s) for:

  • prediction of Patient’s reaction to Drug induction
  • design of Clinical Trials to validate drug efficacy on small subset of patients predicted to react favorable to drug regimen, increasing validity and reliability
  • Genetical identification of patients at no need to have a drug administered if non sensitivity to the drug has been predicted by the genetic marker.

REFERENCES

Tumor response criteria: are they appropriate?

Björn LDM Brücher*1,2, Anton Bilchik2,3, Aviram Nissan2,4, Itzhak Avital2,5 & Alexander Stojadinovic2,6

Treatment for cure is not the endpoint, but the best that can be done is to extend the time of survival to a realistic long term goal and retain a quality of life.
Brücher BLDM, Piso P, Verwaal V et al. Peritoneal carcinomatosis: overview and basics. Cancer Invest.30(3),209–224 (2012).
Brücher BLDM, Swisher S, Königsrainer A et al. Response to preoperative therapy in upper gastrointestinal cancers. Ann. Surg. Oncol.16(4),878–886 (2009).
Miller AB, Hoogstraten B, Staquet M, Winkler A. Reporting results of cancer treatment. Cancer47(1),207–214 (1981).

Other research papers on Cancer and Cancer Therapeutics were published on this Scientific Web site as follows:

What can we expect of tumor therapeutic response?

PIK3CA mutation in Colorectal Cancer may serve as a Predictive Molecular Biomarker for adjuvant Aspirin therapy

Nanotechnology Tackles Brain Cancer

Response to Multiple Cancer Drugs through Regulation of TGF-β Receptor Signaling: a MED12 Control

Personalized medicine-based cure for cancer might not be far away

GSK for Personalized Medicine using Cancer Drugs needs Alacris systems biology model to determine the in silico effect of the inhibitor in its “virtual clinical trial”

Lung Cancer (NSCLC), drug administration and nanotechnology

Non-small Cell Lung Cancer drugs – where does the Future lie?

Cancer Innovations from across the Web

arrayMap: Genomic Feature Mining of Cancer Entities of Copy Number Abnormalities (CNAs) Data

How mobile elements in “Junk” DNA promote cancer. Part 1: Transposon-mediated tumorigenesis.

Cancer Genomics – Leading the Way by Cancer Genomics Program at UC Santa Cruz

Closing the gap towards real-time, imaging-guided treatment of cancer patients.

Closing the gap towards real-time, imaging-guided treatment of cancer patients.

mRNA interference with cancer expression

Search Results for ‘cancer’ on this web site

Cancer Genomics – Leading the Way by Cancer Genomics Program at UC Santa Cruz

Closing the gap towards real-time, imaging-guided treatment of cancer patients.

Lipid Profile, Saturated Fats, Raman Spectrosopy, Cancer Cytology

mRNA interference with cancer expression

Pancreatic cancer genomes: Axon guidance pathway genes – aberrations revealed

Biomarker tool development for Early Diagnosis of Pancreatic Cancer: Van Andel Institute and Emory University

Is the Warburg Effect the cause or the effect of cancer: A 21st Century View?

Crucial role of Nitric Oxide in Cancer

Targeting Glucose Deprived Network Along with Targeted Cancer Therapy Can be a Possible Method of Treatment

 

See comment written for:

Knowing the tumor’s size and location, could we target treatment to THE ROI by applying…..

http://pharmaceuticalintelligence.com/2012/10/16/knowing-the-tumors-size-and-location-could-we-target-treatment-to-the-roi-by-applying-imaging-guided-intervention/

24 Responses

  1. GREAT work.

    I’ll read and comment later on

  2. Highlights of The 2012 Johns Hopkins Prostate Disorders White Paper include:

    A promising new treatment for men with frequent nighttime urination.
    Answers to 8 common questions about sacral nerve stimulation for lower urinary tract symptoms.
    Surprising research on the link between smoking and prostate cancer recurrence.
    How men who drink 6 cups of coffee a day or more may reduce their risk of aggressive prostate cancer.
    Should you have a PSA screening test? Answers to important questions on the controversial USPSTF recommendation.
    Watchful waiting or radical prostatectomy for men with early-stage prostate cancer? What the research suggests.
    A look at state-of-the-art surveillance strategies for men on active surveillance for prostate cancer.
    Locally advanced prostate cancer: Will you benefit from radiation and hormones?
    New drug offers hope for men with metastatic castrate-resistant prostate cancer.
    Behavioral therapy for incontinence: Why it might be worth a try.

    You’ll also get the latest news on benign prostatic enlargement (BPE), also known as benign prostatic hyperplasia (BPH) and prostatitis:
    What’s your Prostate Symptom Score? Here’s a quick quiz you can take right now to determine if you should seek treatment for your enlarged prostate.
    Your surgical choices: a close look at simple prostatectomy, transurethral prostatectomy and open prostatectomy.
    New warnings about 5-alpha-reductase inhibitors and aggressive prostate cancer.

  3. Promising technique.

    INCORE pointed out in detail about the general problem judging response and the stil missing quality in standardization:

    http://www.futuremedicine.com/doi/abs/10.2217/fon.12.78?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dwww.ncbi.nlm.nih.gov

    I did research in response evaluation and prediction for about 15y now and being honest: neither the clinical, nor the molecular biological data proved significant benefit in changing a strategy in patient diagnosis and / or treatment. I would state: this brings us back on the ground and not upon the sky. Additionally it means: we have to ´work harder on that and the WHO has to take responsibility: clinicians use a reponse classification without knowing, that this is just related to “ONE” experiment from the 70′s and that this experiment never had been rescrutinized (please read the Editorial I provided – we use a clinical response classification since more than 30 years worldwide (Miller et al. Cancer 1981) but it is useless !

  4. Dr. BB

    Thank you for your comment.
    Dr. Nir will reply to your comment.
    Regarding the Response Classification in use, it seems that the College of Oncology should champion a task force to revisit the Best Practice in use in this domain and issue a revised version or a new effort for a a new classification system for Clinical Response to treatment in Cancer.

  5. I’m sorry that I was looking for this paper again earlier and didn’t find it. I answered my view on your article earlier.

    This is a method demonstration, but not a proof of concept by any means. It adds to the cacophany of approaches, and in a much larger study would prove to be beneficial in treatment, but not a cure for serious prostate cancer because it is unlikely that it can get beyond the margin, and also because there is overtreatment at the cutoff of PSA at 4.0. There is now a proved prediction model that went to press some 4 months ago. I think that the pathologist has to see the tissue, and the standard in pathology now is for any result that is cancer, two pathologist or a group sitting together should see it. It’s not an easy diagnosis.

    Björn LDM Brücher, Anton Bilchik, Aviram Nissan, Itzhak Avital, & Alexander Stojadinovic. Tumor response criteria: are they appropriate? Future Oncol. (2012) 8(8), 903–906. 10.2217/FON.12.78. ISSN 1479-6694.

    ..Tumor heterogeneity is a ubiquitous phemomenon. In particular, there are important differences among the various types of gastrointestinal (GI) cancers in terms of tumor biology, treatment response and prognosis.

    ..This forms the principal basis for targeted therapy directed by tumor-specific testing at either the gene or protein level. Despite rapid advances in our understanding of targeted therapy for GI cancers, the impact on cancer survival has been marginal.

    ..Can tumor response to therapy be predicted, thereby improving the selection of patients for cancer treatment?

    ..In 2000 theNCI with the European Association for Research and Treatment of Cancer, proposed a replacement of 2D measurement with a decrease in the largest tumor diameter by 30% in one dimension. Tumor response as defined would translate into a 50% decrease for a spherical lesion

    ..We must rethink how we may better determine treatment response in a reliable, reproducible way that is aimed at individualizing the therapy of cancer patients.

    ..we must change the tools we use to assess tumor response. The new modality should be based on empirical evidence that translates into relevant and meaningful clinical outcome data.

    ..This becomes a conundrum of sorts in an era of ‘minimally invasive treatment’.

    ..integrated multidisciplinary panel of international experts – not sure that that will do it

    Several years ago i heard Stamey present the totality of his work at Stanford, with great disappointment over hsPSA that they pioneered in. The outcomes were disappointing.

    I had published a review of all of our cases reviewed for 1 year with Marguerite Pinto.
    There’s a reason that the physicians line up outside of her office for her opinion.
    The review showed that a PSA over 24 ng/ml is predictive of bone metastasis. Any result over 10 was as likely to be prostatitis, BPH or cancer.

    I did an ordinal regression in the next study with Gustave Davis using a bivariate ordinal regression to predict lymph node metastasis using the PSA and the Gleason score. It was better than any univariate model, but there was no followup.

    I reviewed a paper for Clin Biochemistry (Elsevier) on a new method for PSA, very different than what we are familiar with. It was the most elegant paper I have seen in the treatment of the data. The model could predict post procedural time to recurrence to 8 years.

    • I hope we are in agreement on the fact that imaging guided interventions are needed for better treatment outcome. The point I’m trying to make in this post is that people are investing in developing imaging guided intervention and it is making progress.

      Over diagnosis and over treatment is another issue altogether. I think that many of my other posts are dealing with that.

  6. Tumor response criteria: are they appropriate?
    Future Oncology 2012; 8(8): 903-906 , DOI 10.2217/fon.12.78 (doi:10.2217/fon.12.78)
    Björn LDM Brücher, Anton Bilchik, Aviram Nissan, Itzhak Avital & Alexander Stojadinovic
    Tumor heterogeneity is a problematic because of differences among the metabolic variety among types of gastrointestinal (GI) cancers, confounding treatment response and prognosis.
    This is in response to … a group of investigators from Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada who evaluate the feasibility and safety of magnetic resonance (MR) imaging–controlled transurethral ultrasound therapy for prostate cancer in humans. Their study’s objective was to prove that using real-time MRI guidance of HIFU treatment is possible and it guarantees that the location of ablated tissue indeed corresponds to the locations planned for treatment.
    1. There is a difference between expected response to esophageal or gastric neoplasms both biologically and in expected response, even given variability within a class. The expected time to recurrence is usually longer in the latter case, but the confounders are – age at time of discovery, biological time of detection, presence of lymph node and/or distant metastasis, microscopic vascular invasion.
    2. There is a long latent period in abdominal cancers before discovery, unless a lesion is found incidentally in surgery for another reason.
    3. The undeniable reality is that it is not difficult to identify the main lesion, but it is difficult to identify adjacent epithelium that is at risk (transitional or pretransitional). Pathologists have a very good idea about precancerous cervical neoplasia.

    The heterogeneity rests within each tumor and between the primary and metastatic sites, which is expected to be improved by targeted therapy directed by tumor-specific testing. Despite rapid advances in our understanding of targeted therapy for GI cancers, the impact on cancer survival has been marginal.

    The heterogeneity is a problem that will take at least another decade to unravel because of the number of signaling pathways and the crosstalk that is specifically at issue.

    I must refer back to the work of Frank Dixon, Herschel Sidransky, and others, who did much to develop a concept of neoplasia occurring in several stages – minimal deviation and fast growing. These have differences in growth rates, anaplasia, and biochemical. This resembles the multiple “hit” theory that is described in “systemic inflammatory” disease leading to a final stage, as in sepsis and septic shock.
    In 1920, Otto Warburg received the Nobel Prize for his work on respiration. He postulated that cancer cells become anaerobic compared with their normal counterpart that uses aerobic respiration to meet most energy needs. He attributed this to “mitochondrial dysfunction. In fact, we now think that in response to oxidative stress, the mitochondrion relies on the Lynen Cycle to make more cells and the major source of energy becomes glycolytic, which is at the expense of the lean body mass (muscle), which produces gluconeogenic precursors from muscle proteolysis (cancer cachexia). There is a loss of about 26 ATP ~Ps in the transition.
    The mitochondrial gene expression system includes the mitochondrial genome, mitochondrial ribosomes, and the transcription and translation machinery needed to regulate and conduct gene expression as well as mtDNA replication and repair. Machinery involved in energetics includes the enzymes of the Kreb’s citric acid or TCA (tricarboxylic acid) cycle, some of the enzymes involved in fatty acid catabolism (β-oxidation), and the proteins needed to help regulate these systems. The inner membrane is central to mitochondrial physiology and, as such, contains multiple protein systems of interest. These include the protein complexes involved in the electron transport component of oxidative phosphorylation and proteins involved in substrate and ion transport.
    Mitochondrial roles in, and effects on, cellular homeostasis extend far beyond the production of ATP, but the transformation of energy is central to most mitochondrial functions. Reducing equivalents are also used for anabolic reactions. The energy produced by mitochondria is most commonly thought of to come from the pyruvate that results from glycolysis, but it is important to keep in mind that the chemical energy contained in both fats and amino acids can also be converted into NADH and FADH2 through mitochondrial pathways. The major mechanism for harvesting energy from fats is β-oxidation; the major mechanism for harvesting energy from amino acids and pyruvate is the TCA cycle. Once the chemical energy has been transformed into NADH and FADH2 (also discovered by Warburg and the basis for a second Nobel nomination in 1934), these compounds are fed into the mitochondrial respiratory chain.
    The hydroxyl free radical is extremely reactive. It will react with most, if not all, compounds found in the living cell (including DNA, proteins, lipids and a host of small molecules). The hydroxyl free radical is so aggressive that it will react within 5 (or so) molecular diameters from its site of production. The damage caused by it, therefore, is very site specific. The reactions of the hydroxyl free radical can be classified as hydrogen abstraction, electron transfer, and addition.
    The formation of the hydroxyl free radical can be disastrous for living organisms. Unlike superoxide and hydrogen peroxide, which are mainly controlled enzymatically, the hydroxyl free radical is far too reactive to be restricted in such a way – it will even attack antioxidant enzymes. Instead, biological defenses have evolved that reduce the chance that the hydroxyl free radical will be produced and, as nothing is perfect, to repair damage.
    Currently, some endogenous markers are being proposed as useful measures of total “oxidative stress” e.g., 8-hydroxy-2’deoxyguanosine in urine. The ideal scavenger must be non-toxic, have limited or no biological activity, readily reach the site of hydroxyl free radical production (i.e., pass through barriers such as the blood-brain barrier), react rapidly with the free radical, be specific for this radical, and neither the scavenger nor its product(s) should undergo further metabolism.
    Nitric oxide has a single unpaired electron in its π*2p antibonding orbital and is therefore paramagnetic. This unpaired electron also weakens the overall bonding seen in diatomic nitrogen molecules so that the nitrogen and oxygen atoms are joined by only 2.5 bonds. The structure of nitric oxide is a resonance hybrid of two forms.
    In living organisms nitric oxide is produced enzymatically. Microbes can generate nitric oxide by the reduction of nitrite or oxidation of ammonia. In mammals nitric oxide is produced by stepwise oxidation of L-arginine catalyzed by nitric oxide synthase (NOS). Nitric oxide is formed from the guanidino nitrogen of the L-arginine in a reaction that consumes five electrons and requires flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN) tetrahydrobiopterin (BH4), and iron protoporphyrin IX as cofactors. The primary product of NOS activity may be the nitroxyl anion that is then converted to nitric oxide by electron acceptors.
    The thiol-disulfide redox couple is very important to oxidative metabolism. GSH is a reducing cofactor for glutathione peroxidase, an antioxidant enzyme responsible for the destruction of hydrogen peroxide. Thiols and disulfides can readily undergo exchange reactions, forming mixed disulfides. Thiol-disulfide exchange is biologically very important. For example, GSH can react with protein cystine groups and influence the correct folding of proteins, and it GSH may play a direct role in cellular signaling through thiol-disulfide exchange reactions with membrane bound receptor proteins (e.g., the insulin receptor complex), transcription factors (e.g., nuclear factor κB), and regulatory proteins in cells. Conditions that alter the redox status of the cell can have important consequences on cellular function.
    So the complexity of life is not yet unraveled.

    Can tumor response to therapy be predicted, thereby improving the selection of patients for cancer treatment?
    The goal is not just complete response. Histopathological response seems to be related post-treatment histopathological assessment but it is not free from the challenge of accurately determining treatment response, as this method cannot delineate whether or not there are residual cancer cells. Functional imaging to assess metabolic response by 18-fluorodeoxyglucose PET also has its limits, as the results are impacted significantly by several variables:

    • tumor type
    • sizing
    • doubling time
    • anaplasia?
    • extent of tumor necrosis
    • type of antitumor therapy and the time when response was determined.
    The new modality should be based on individualized histopathology as well as tumor molecular, genetic and functional characteristics, and individual patients’ characteristics, a greater challenge in an era of ‘minimally invasive treatment’.
    This listing suggests that for every cancer the following data has to be collected (except doubling time). If there are five variables, the classification based on these alone would calculate to be very sizable based on Eugene Rypka’s feature extraction and classification. But looking forward, time to remission and disease free survival are additionally important. Treatment for cure is not the endpoint, but the best that can be done is to extend the time of survival to a realistic long term goal and retain a quality of life.

    Brücher BLDM, Piso P, Verwaal V et al. Peritoneal carcinomatosis: overview and basics. Cancer Invest.30(3),209–224 (2012).
    Brücher BLDM, Swisher S, Königsrainer A et al. Response to preoperative therapy in upper gastrointestinal cancers. Ann. Surg. Oncol.16(4),878–886 (2009).
    Miller AB, Hoogstraten B, Staquet M, Winkler A. Reporting results of cancer treatment. Cancer47(1),207–214 (1981).
    Therasse P, Arbuck SG, Eisenhauer EA et al. New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J. Natl Cancer Inst.92(3),205–216 (2000).
    Brücher BLDM, Becker K, Lordick F et al. The clinical impact of histopathological response assessment by residual tumor cell quantification in esophageal squamous cell carcinomas. Cancer106(10),2119–2127 (2006).

    • Dr. Larry,

      Thank you for this comment.

      Please carry it as a stand alone post, Dr. Ritu will refer to it and reference it in her FORTHCOMING pst on Tumor Response which will integrate multiple sources.

      Please execute my instruction

      Thank you

    • Thank you Larry for this educating comment. It explains very well why the Canadian investigators did not try to measure therapy response!

      What they have demonstrated is the technological feasibility of coupling a treatment device to an imaging device and use that in order to guide the treatment to the right place.

      the issue of “choice of treatment” to which you are referring is not in the scope of this publication.
      The point is: if one treatment modality can be guided, other can as well! This should encourage others, to try and develop imaging-based treatment guidance systems.

  7. The crux of the matter in terms of capability is that the cancer tissue, adjacent tissue, and the fibrous matrix are all in transition to the cancerous state. It is taught to resect leaving “free margin”, which is better aesthetically, and has had success in breast surgery. The dilemma is that the patient may return, but how soon?

    • Correct. The philosophy behind lumpectomy is preserving quality of life. It was Prof. Veronesi (IEO) who introduced this method 30 years ago noticing that in the majority of cases, the patient will die from something else before presenting recurrence of breast cancer..

      It is well established that when the resection margins are declared by a pathologist (as good as he/she could be) as “free of cancer”, the probability of recurrence is much lower than otherwise.

  8. Dr. Larry,

    To assist Dr. Ritu, PLEASE carry ALL your comments above into a stand alone post and ADD to it your comment on my post on MIS

    Thank you

  9. Great post! Dr. Nir, can the ultrasound be used in conjunction with PET scanning as well to determine a spatial and functional map of the tumor. With a disease like serous ovarian cancer we typically see an intraperitoneal carcimatosis and it appears that clinicians are wanting to use fluorogenic probes and fiberoptics to visualize the numerous nodules located within the cavity Also is the technique being used mainy for surgery or image guided radiotherapy or can you use this for detecting response to various chemotherapeutics including immunotherapy.

    • Ultrasound can and is actually used in conjunction with PET scanning in many cases. The choice of using ultrasound is always left to the practitioner! Being a non-invasive, low cost procedure makes the use of ultrasound a non-issue. The down-side is that because it is so easy to access and operate, nobody bothers to develop rigorous guidelines about using it and the benefits remains the property of individuals.

      In regards to the possibility of screening for ovarian cancer and characterising pelvic masses using ultrasound I can refer you to scientific work in which I was involved:

      1. VAES (E.), MANCHANDA (R), AUTIER, NIR (R), NIR (D.), BLEIBERG (H.), ROBERT (A.), MENON (U.). Differential diagnosis of adnexal masses: Sequential use of the Risk of Malignancy Index and a novel computer aided diagnostic tool. Published in Ultrasound in Obstetrics & Gynecology. Issue 1 (January). Vol. 39. Page(s): 91-98.

      2. VAES (E.), MANCHANDA (R), NIR (R), NIR (D.), BLEIBERG (H.), AUTIER (P.), MENON (U.), ROBERT (A.). Mathematical models to discriminate between benign and malignant adnexal masses: potential diagnostic improvement using Ovarian HistoScanning. Published in International Journal of Gynecologic Cancer (IJGC). Issue 1. Vol. 21. Page(s): 35-43.

      3. LUCIDARME (0.), AKAKPO (J.-P.), GRANBERG (S.), SIDERI (M.), LEVAVI (H.), SCHNEIDER (A.), AUTIER (P.), NIR (D.), BLEIBERG (H.). A new computer aided diagnostic tool for non-invasive characterisation of malignant ovarian masses: Results of a multicentre validation study. Published in European Radiology. Issue 8. Vol. 20. Page(s): 1822-1830.

      Dror Nir, PhD
      Managing partner

      BE: +32 (0) 473 981896
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      web: http://www.radbee.com/
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  10. totally true and i am very thankfull for these briliant comments.

    Remember: 10years ago: every cancer researcher stated: “look at the tumor cells only – forget the stroma”. The era of laser-captured tumor-cell dissection started. Now , everyone knows: it is a system we are looking at and viewing and analyzing tumor cells only is really not enough.

    So if we would be honest, we would have to declare, that all data, which had been produced 13-8years ago, dealing with laser capture microdissection, that al these data would need a re-scrutinization, cause the influence of the stroma was “forgotten”. I ‘d better not try thinking about the waisted millions of dollars.

    If we keep on being honest: the surgeon looks at the “free margin” in a kind of reductionable model, the pathologist is more the control instance. I personally see the pathologist as “the control instance” of surgical quality. Therefore, not the wish of the surgeon is important, the objective way of looking into problems or challenges. Can a pathologist always state, if a R0-resection had been performed ?

    The use of the Resectability Classification:
    There had been many many surrogate marker analysis – nothing new. BUT never a real substantial well tought through structured analysis had been done: mm by mm by mm by mm and afterwards analyzing that by a ROC analysis. BUt against which goldstandard ? If you perform statistically a ROC analysis – you need a golstandard to compare to. Therefore what is the real R0-resectiòn? It had been not proven. It just had been stated in this or that tumor entity that this or that margin with this margin free mm distance or that mm distance is enough and it had been declared as “the real R0-classification”. In some organs it is very very difficult and we all (surgeons, pathologists, clinicians) that we always get to the limit, if we try interpretating the R-classification within the 3rd dimension. Often it is just declared and stated.

    Otherwise: if lymph nodes are negative it does not mean, lymph nodes are really negative, cause up to 38% for example in upper GI cancers have histological negative lymph nodes, but immunohistochemical positive lymph nodes. And this had been also shown by Stojadinovic at el analyzing the ultrastaging in colorectal cancer. So the 4th dimension of cancer – the lymph nodes / the lymphatic vessel invasion are much more important than just a TNM classification, which unfortunately does often not reflect real tumor biology.

    AS we see: cancer has multifactorial reasons and it is necessary taking the challenge performing high sophisticated research by a multifactorial and multidisciplinary manner.

    Again my deep and heartly thanks for that productive and excellent discussion !

    • Dr. BB,

      Thank you for your comment.

      Multidisciplinary perspectives have illuminated the discussion on the pages of this Journal.

      Eager to review Dr. Ritu’s forthcoming paper – the topic has a life of its own and is embodied in your statement:

      “the 4th dimension of cancer – the lymph nodes / the lymphatic vessel invasion are much more important than just a TNM classification, which unfortunately does often not reflect real tumor biology.”

    • Thank you BB for your comment. You have touched the core limitation of healthcare professionals: how do we know that we know!

      Do we have a reference to each of the test we perform?

      Do we have objective and standardise quality measures?

      Do we see what is out-there or are we imagining?

      The good news: Everyday we can “think” that we learned something new. We should be happy with that, even if it is means that we learned that yesterday’s truth is not true any-more and even if we are likely to be wrong again…:)

      But still, in the last decades, lots of progress was made….

  11. Dr. Nir,
    I thoroughly enjoyed reading your post as well as the comments that your post has attracted. There were different points of view and each one has been supported with relevant examples in the literature. Here are my two cents on the discussion:
    The paper that you have discussed had the objective of finding out whether real-time MRI guidance of treatment was even possible and if yes, and also if the treatment could be performed in accurate location of the ROI? The data reveals they were pretty successful in accomplishing their objective and of course that gives hope to the imaging-based targeted therapies.
    Whether the ROI is defined properly and if it accounts for the real tumor cure, is a different question. Role of pathologists and the histological analysis they bring about to the table cannot be ruled out, and the absence of a defined line between the tumor and the stromal region in the vicinity is well documented. However, that cannot rule out the value and scope of imaging-based detection and targeted therapy. After all, it is seminal in guiding minimally invasive surgery. As another arm of personalized medicine-based cure for cancer, molecular biologists at MD Anderson have suggested molecular and genetic profiling of the tumor to determine genetic aberrations on the basis of which matched-therapy could be recommended to patients. When phase I trial was conducted, the results were obtained were encouraging and the survival rate was better in matched-therapy patients compared to unmatched patients. Therefore, everytime there is more to consider when treating a cancer patient and who knows a combination of views of oncologists, pathologists, molecular biologists, geneticists, surgeons would device improvised protocols for diagnosis and treatment. It is always going to be complicated and generalizations would never give an answer. Smart interpretations of therapies – imaging-based or others would always be required!

    Ritu

    • Dr. Nir,
      One of your earlier comments, mentioned the non invasiveness of ultrasound, thus, it’s prevalence in use for diagnosis.

      This may be true for other or all areas with the exception of Mammography screening. In this field, an ultrasound is performed only if a suspected area of calcification or a lump has been detected in the routine or patient-initiated request for ad hoc mammography secondery to patient complain of pain or patient report of suspected lump.

      Ultrasound in this field repserents ascalation and two radiologists review.

      It in routine use for Breast biopsy.

    • Thanks Ritu for this supporting comment. The worst enemy of finding solutions is doing nothing while using the excuse of looking for the “ultimate solution” . Personally, I believe in combining methods and improving clinical assessment based on information fusion. Being able to predict, and then timely track the response to treatment is a major issue that affects survival and costs!

Judging the ‘Tumor response’-there is more food for thought

http://pharmaceuticalintelligence.com/2012/12/04/judging-the-tumor-response-there-is-more-food-for-thought/

13 Responses

  1. Dr. Sanexa
    you have brought up an interesting and very clinically relevant point: what is the best measurement of response and 2) how perspectives among oncologists and other professionals differ on this issues given their expertise in their respective subspecialties (immunologist versus oncologist. The advent of functional measurements of tumors (PET etc.) seems extremely important in the therapeutic use AND in the development of these types of compounds since usually a response presents (in cases of solid tumors) as either a lack of growth of the tumor or tumor shrinkage. Did the authors include an in-depth discussion of the rapidity of onset of resistance with these types of compounds?
    Thanks for the posting.

  2. Dr. Williams,
    Thanks for your comment on the post. The editorial brings to attention a view that although PET and other imaging methods provide vital information on tumor growth, shrinkage in response to a therapy, however, there are more aspects to consider including genetic and molecular characteristics of tumor.
    It was an editorial review and the authors did not include any in-depth discussion on the rapidity of onset of resistance with these types of compounds as the focus was primarily on interpreting tumor response.
    I am glad you found the contents of the write-up informative.
    Thanks again!
    Ritu

  3. Thank you for your wonderful comment and interpretation. Dr.Sanexa made a brilliant comment.

    May I allow myself putting my finger deeper into this wound ? Cancer patients deserve it.

    It had been already pointed out by international experts from Munich, Tokyo, Hong-Kong and Houston, dealing with upper GI cancer, that the actual response criteria are not appropriate and moreover: the clinical response criteria in use seem rather to function as an alibi, than helping to differentiate and / or discriminate tumor biology (Ann Surg Oncol 2009):

    http://www.ncbi.nlm.nih.gov/pubmed/19194759

    The response data in a phase-II-trial (one tumor entity, one histology, one treatment, one group) revealed: clinical response evaluation according to the WHO-criteria is not appropriate to determine response:

    http://www.ncbi.nlm.nih.gov/pubmed/15498642

    Of course, there was a time, when it seemed to be useful and this also has to be respected.

    There is another challenge: using statistically a ROC and resulting in thresholds. This was, is and always be “a clinical decision only” and not the decision of the statistician. The clinician tells the statistician, what decision, he wants to make – the responsibility is enormous. Getting back to the roots:
    After the main results of the Munich-group had been published 2001 (Ann Surg) and 2004 (J Clin Oncol):

    http://www.ncbi.nlm.nih.gov/pubmed/11224616

    http://www.ncbi.nlm.nih.gov/pubmed/14990646

    the first reaction in the community was: to difficult, can’t be, not re-evaluated, etc.. However, all evaluated cut-offs / thresholds had been later proven to be the real and best ones by the MD Anderson Cancer Center in Houston, Texas. Jaffer Ajani – a great and critical oncologist – pushed that together with Steve Swisher and they found the same results. Than the upper GI stakeholders went an uncommon way in science: they re-scrutinized their findings. Meanwhile the Goldstandard using histopathology as the basis-criterion had been published in Cancer 2006.

    http://www.ncbi.nlm.nih.gov/pubmed/16607651

    Not every author, who was at the authorlist in 2001 and 2004 wanted to be a part of this analysis and publication ! Why ? Everyone should judge that by himself.

    The data of this analysis had been submitted to the New England Journal of Medicine. In the 2nd review stage process, the manuscript was rejected. The Ann Surg Oncol accepted the publication: the re-scrutinized data resulted in another interesting finding: in the future maybe “one PET-scan” might be appropriate predicting the patient’s response.

    Where are we now ?

    The level of evidence using the response criteria is very low: Miller’s (Cancer 1981) publication belonged to ”one single” experiment from Moertel (Cancer 1976). During that time, there was no definition of “experiences” rather than “oncologists”. These terms had not been in use during that time.

    Additionally they resulted in a (scientifically weak) change of the classification, published by Therasse (J Natl Cancer Inst 2000). Targeted therapy did not result in a change so far. In 2009, the international upper GI experts sent their publication of the Ann Surg Oncol 2009 to the WHO but without any kind of reaction.

    Using molecular biological predictive markers within the last 10years all seem to have potential.

    http://www.ncbi.nlm.nih.gov/pubmed/20012971

    http://www.ncbi.nlm.nih.gov/pubmed/18704459

    http://www.ncbi.nlm.nih.gov/pubmed/17940507

    http://www.ncbi.nlm.nih.gov/pubmed/17354029

    But, experts are aware: the real step breaking barriers had not been performed so far. Additionally, it is very important in trying to evaluate and / predict response, that not different tumor entities with different survival and tumor biology are mixed together. Those data are from my perspective not helpful, but maybe that is my own Bias (!) of my view.

    INCORE, the International Consortium of Research Excellence of the Theodor-Billroth-Academy, was invited publishing the Editorial in Future Oncology 2012. The consortium pointed out, that living within an area of ‘prove of principle’ and also trying to work out level of evidence in medicine, it is “the duty and responsibility” of every clinician, but also of the societies and institutions, also of the WHO.

    Complete remission is not the only goal, as experts dealing with ‘response-research’ are aware. It is so frustrating for patients and clinicians: there is a rate of those patients with complete remission, who develop early recurrence ! This reflects, that complete remission cannot function as the only criterion describing response !

    Again, my heartly thanks, that Dr.Sanexa discussed this issue in detail.
    I hope, I found the way explaining the way of development and evaluating response criteria properly and in a differentiated way of view. From the perspective of INCORE:

    “an interdisciplinary initiative with all key stake¬holders and disciplines represented is imperative to make predictive and prognostic individualized tumor response assessment a modern-day reality. The integrated multidisciplinary panel of international experts need to define how to leverage existing data, tissue and testing platforms in order to predict individual patient treatment response and prognosis.”

  4. Dr. Brucher,

    First of all thanks for expressing your views on the ‘tumor response’ in a comprehensive way. You are the first author of the editorial review one of the prominent people who has taken part in the process of defining tumor response and I am glad that you decided to write a comment on the writeup.
    The topic has been explained well in an immaculate manner and that it further clarifies the need for the perfect markers that would be able to evaluate and predict tumor response. There are, as you mentioned, some molecular markers available including VEGF, cyclins, that have been brought to focus in the context of squamous cell carcinoma.

    It would be great if you could be the guest author for our blog and we could publish your opinion (comment on this blog post) as a separate post. Please let us know if it is OK with you.

    Thanks again for your comment
    Ritu

  5. Thank you all to the compelling discussions, above.

    Please review the two sources on the topic I placed at the bottom of the post, above as post on this Scientific Journal,

    All comments made to both entries are part of thisvdiscussion, I am referring to Dr. Nir’s post on size of tumor, to BB comment to Nir’s post, to Larry’ Pathologist view on Tumors and my post on remission and minimally invasive surgery (MIS).

    Great comments by Dr. Williams, BB and wonderful topic exposition by Dr. Ritu.

  6. Aviva,
    Thats a great idea. I will combine all sources referred by you, the post on tumor imaging by Dr. Nir and the comments made on the these posts including Dr. Brucher’s comments in a new posts.
    Thanks
    Ritu

    • Great idea, ask Larry, he has written two very long important comments on this topic, one on Nir’s post and another one, ask him where, if it is not on MIS post. GREAT work, Ritu, integration is very important. Dr, Williams is one of our Gems.

    • Assessing tumour response it is not an easy task!Because tumours don’t change,but happilly our knowlege(about them) does really change,is everchanging(thans god!).In the past we had the Recist Criteria,then the Modified Recist Criteria,becausa of Gist and other tumors.At this very moment,these are clearly insuficient.We do need more ,new validated facing the reality of nowadays.A great,enormoust post Dr Ritu!Congratulations!

 

 

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