Bevacizumab In Colon Cancer – “A Shot Across The Bowel”

Colon2 130320.01 lo resAn E-Publication article in the February Journal of Clinical Oncology analyzes the cost efficacy of Bevacizumab for colon cancer. Bevacizumab, sold commercially as Avastin, has become a standard in the treatment of patients with advanced colorectal cancer. Indeed, Bevacizumab plus FOLFOX or FOLFIRI, are supported by NCCN guidelines and patients who receive one of these regimens are usually switched to the other at progression.

A Markov computer model explored the cost and efficacy of Bevacizumab in the first and second line setting using a well-established metric known as a Quality-Adjusted Life Year (QALY). In today’s dollars $100,000 per QALY is considered a threshold for utility of any treatment. To put this bluntly, the medical system values a year of yavastinour life at $100,000. The authors confirmed that Bevacizumab prolongs survival but that it does so at significantly increased costs. By their most optimistic projections, Bevacizumab + FOLFOX come in at more than $200,000 per QALY. Similar results were reported for Canadian, British and Japanese costs. Though more favorable, the results with FOLFIRI + Bevacizumab still came in above the $100,000 threshold.

No one doubts that Bevacizumab provides improved outcomes. It’s the incremental costs that remain an issue. Society is now confronting an era where the majority of new cancer agents come in at a cost in excess of $10,000 per month. Where and how will we draw the line that designates some treatments unaffordable? On the one hand, clinical therapies could be made available only to the “highest bidder.” However, this is contrary to the western societal ethic that holds that medical care should be available to all regardless of ability to pay. Alternatively, increasingly narrow definitions could be applied to new drugs making these treatments available to a shrinking minority of those who might actually benefit; a form of “evidence-based” rationing. A much more appealing option would be to apply validated drug predication assays for the intelligent selection of treatment candidates.
Avastin-MOA-Overview
In support of the latter, the authors state, “Bevacizumab potentially could be improved with the use of an effective biomarker to select patients most likely to benefit.” This is something that genomic (DNA) profiling has long sought to achieve but, so far, has been unable to do. This conceptual approach however is demonstrably more attractive in that all patients have equal access, futile care is avoided and the costs saved would immediately provide highly favorable QALY’s as the percentage of responders improved.

Similar to the recent reports from the National Health Service of England, the American public now confronts the challenge of meeting the needs of a growing population of cancer patients at ever-higher costs. It is only a matter of time before these same metrics described for colon cancer are applied to lung, ovarian and other cancers for which Avastin is currently approved.

At what point will the American medical system recognize the need for validated predictive platforms, like EVA-PCD analyses, that have the proven capacity to save both money and lives? We can only wonder.

In Cancer Care, It Appears that More Is Less

With the interest in “value oncology” and cost containment, a report appeared in the December 2014 Journal of Clinical Oncology that analyzed the impact of the Medicare Prescription Drug Act of 2003 (MMA) on chemotherapy administration in an environment of diminishing reimbursement to physicians.

Prior to the passage of the MMA, oncologists were compensated at 95% of the average wholesale price of a drug. The government accounting office found that the larger medical oncology practices could form “buyers groups” and purchase drugs at lower prices allowing them to pocket the difference. A 2003 New York Times article decried the practice as a “Chemotherapy Concession” and Medicare responded. The MMA of 2003 changed the policy so that chemotherapy drugs were reimbursed at the national average sale price plus 6%. It was hoped that this would result in cost savings.

Practices were divided into Fee-For-Service and Integrated-Health-Networks, the latter largely HMOs and the Veterans’ Administration. It was expected that integrated networks would be less affected since their physicians are salaried and an 11% disparity between the two groups was noted for MMA agents. However, a number of interesting, unexpected and instructive trends emerged.

First, contrary to expectations, the overall use of chemotherapy actually increased following the passage of the MMA.

Second, the cost of cancer care continued to increase unabated following the passage of the MMA.

Finally, changes in drug use appeared to be disease-specific. Colorectal and small cell lung cancer patients saw a decline in the use of MMA affected drugs while non-small lung cancer showed an increase for both fee-for-service and integrated networks. With the overall use of MMA drugs in lung cancer increasing by 1.6 fold, the same drug use increase in the integrated (salaried) groups was 6.3 fold higher.

Among the findings the authors note “reimbursement after MMA passage appears to have had less impact on prescribing patterns in fee for service than the introduction of new drugs and clinical evidence.” This gives the lie to the idea that practicing oncologists are driven by self-gain, a popular narrative in the current political environment.

The authors did find that passage of MMA “resulted in consolidations and acquisitions of practices by hospitals, many of which were able to purchase chemotherapy drugs at discounted rates through the federal 340B* program. Although the full impact of these changes is not known, the shift of chemotherapy from community practices to hospital outpatient settings is associated with higher total costs.”

Community fee-for-service oncologists represent a qualified, yet under-appreciated resource for patients. While their academic brethren bask in the limelight, it is private practitioners who must make sense of the complex and overly dose-intensive treatment schedules handed down to them by ivory tower investigators. We now come to learn that while fee-for-service doctors have been forced to consolidate, join hospital systems, or retire, the cost of cancer care has actually climbed by 66% since the passage of MMA.

It would appear that this experiment has failed. Costs were not contained and drug use was not curtailed. What other bright ideas can we expect from policymakers who seem intent on bending medical care to their wishes at the expense of doctors and their patients?

 

*The 340 B program was originally created by the Federal government to allow charitable hospitals to save money on expensive drugs by allowing them to purchase them at deep discounts. Over time a growing number of “not-for-profit” hospitals demanded the same consideration. Subsequent analyses have found that the majority of the hospitals that now take advantage of 340B actually provide less charity care than the national average. Hospitals that charge full fee for drug administration can then pocket the difference.

The Cost of Chemotherapy Comes Home to Roost

NY TImes rotatedMedical care in the United States is a $2.7 trillion industry. That translates into almost $8,000 per person per year. One of the most expensive aspects is cancer care. This has caught the attention of the medical oncology community. A highly touted editorial in the October, 2012 New York Times described the unwillingness of physicians at Memorial Sloan Kettering Cancer Center to add a new and expensive drug to their formulary. The authors opined that the new drug provided outcomes similar to those for an existing drug, yet cost twice the price.

A subsequent editorial in the Journal of Clinical Oncology from MD Anderson (Cancer Drugs in the United States: Justum Pretium – The Just Price) further examined the cost of cancer therapy, profit margins and some of the drivers. Among the points raised was the fact that the monthly cost of chemotherapy had more than doubled from $4,500 to $10,000 in just one decade. Furthermore, of twelve anticancer drugs approved in 2012, only three prolonged survival and for 2 of 3 by less than two months. Despite these marginal benefits, nine of the twelve drugs were priced at more than $10,000 a month.
60 Minutes
This caught the attention of the media with 60 Minutes recently conducting an interview with the authors of the New York Times editorial. While Lesley Stahl pointedly decried the rather marginal 4 – 6% markups that many physicians apply to cover their costs of chemotherapy drug administration, there are in fact much darker forces at work.

The cost of cancer drug development reflects the expense of human subject trials, cost of R & D, the regulatory burden, as well as an extraordinary new drug failure rate. Fully 50% of new agents fail at Phase III (the last and most expensive type of study). Phase III trials cost tens to hundreds of millions of dollars. An article in Forbes magazine stated that the average drug approved by the FDA now costs, not the one billion dollars often cited but instead five billion dollars when one factors in the failures against the rare successes.

Drug development begins with a novel idea, a small molecule and a few preliminary results. At this point the expenses are low but the drug is of little commercial value. As one moves from cell lines to animal models, the price goes up but the value remains low. The cost of formulation, toxicology and animal studies continue to add up but doesn’t influence interest in the agent. Then come human studies as the Phase I trials begin. Specialized institutions across the United States accept contracts with the pharmaceutical industry to examine the tolerability of the drug. I use that term advisably as the intent of Phase I trials is only to determine safety not efficacy. If the drug proves tolerable, it then moves to Phase II to explore it’s activity against cancer. This is where the money starts flowing.

Phase II clinical trials are conducted by university medical centers. Each patient accrued costs the pharmaceutical sponsors from $25,000 to more than $50,000 per patient. As drugs are tested in many schedules against many diseases it can take hundreds or even thousands of patients for statistical analysis. Nonetheless, a successful Phase II trial showing meaningful benefit in a cancer population generates a buzz and the drug’s value begins to gain traction. With hundreds of millions already expended, the final testing pits the new drug against an existing standard in one or more Phase III trials. Endpoints like progression-free-survival must then fold into overall survival if the drug has any hope to gain full approval by the FDA. These registration triaus-money-with-black-backdrop-1024x640ls at the national or international Phase III level cost up to $100,000 per patient and most of the participating institutions are university-based medical centers or their affiliates.

So, why do chemotherapy drugs cost so much? While it may be convenient to point fingers at the pharmaceutical industry, private practitioners or the smaller institutions, the university medical centers and their affiliates have added greatly to the costs of drug development as have the increasingly byzantine regulatory standards that have so encumbered the process that it is now increasingly only a rich man’s game.

We applaud the investigators at Memorial Sloan-Kettering for focusing attention upon this important matter. We applaud 60 Minutes and the authors of the Journal of Clinical Oncology editorial for their exploration of the same. While the willingness of these physicians to raise the issue is laudable, the solution may be somewhat more complex than these authors have been willing to admit. Before we vilify private practitioners who have time and again proven to be more efficient and less expensive purveyors of cancer care than their university brethren we should examine other drivers.

To wit, a review of one of the NY Times editorial author’s conflicts of interest statement listed in the 2012 American Society of Clinical Oncology proceedings revealed that his co-presenters at this national meeting disclosed fully 16 separate pharmaceutical affiliations for employment or leadership positions, consultant or advisory roles, stock ownership, honoraria, research funds, expert testimony, or other remuneration. With the research community enjoying these levels of compensation, it must be surmised that the costs of clinical trials reflect in part these expenditures. When one adds to this, the increasingly burdensome regulatory environment, the cost of cancer chemotherapy development appears to have plenty of blame to go around.

The Rising Cost of Cancer Research: Is It Necessary?

JCO coverFor anyone engaged in developmental therapeutics and for those patients who need new approaches to their cancers, an editorial in the Journal of Clinical Oncology casts a disturbing light on the field The authors examine the impact of the growing research bureaucracy upon the conduct of clinical trials. They use Thomas Edison, who filed 1,093 U.S. patents, to exemplify successful trial and error research. By inference, they suggest that if Mr. Edison were working today in the modern regulatory environment we would all be reading this blog by candlelight. While much of Edison’s work focused upon household conveniences like light bulbs and phonographs, the principals that underlie discovery work are every bit the same.

Although regulations have been put in place to protect human subjects, the redundancies and rigorous re-reviews have outstripped their utility for the patients in need. The process has become so complex  that it is now necessary for many institutions to use professional organizations to conduct trials that could easily have done in the past by an investigator with a small staff. These clinical research organizations (CRO’s) are under the gun to adhere to an ever growing collection of standards. Thus, every detail of every consent form is pored over sometimes for years. This has had the effect of driving up the cost of research such that the average Phase III clinical trial conducted in the 1990s that cost $3,000 to $5,000 per accrued patient, today costs between $75,000 and $125,000 per patient. Despite this, the safety of individuals is no better protected today than it was 30 years ago when all of this was done easily and cheaply.

While funding for cancer research has increased slowly, the cancer research bureaucracy has exploded. One need only visit any medium to large size hospital or university medical center to witness the expansion of these departments. Are we safer? Do our patients do better? The answer is a resounding “No.” In 2013, according to the authors,  the average patient spent a mere 53 seconds reviewing their consent forms before signing them, while the average parent, signing on behalf of their child, spent only 13 seconds.

The take home messages are several. First, the regulatory process has become too cumbersome. Were this the cost of scientific advance we would accept it as a fact of life, but patients are not safer, trials are not faster and outcomes are not being enhanced. Second, the cancer research process has overwhelmed and undermined cancer researchers. In keeping with Pournelle’s Iron Law of Bureaucracy, “. . . in any bureaucratic organization there will be two kinds of people: those who work to further the actual goals of the organization, and those who work for the organization itself.”Is there anyone who donates to the American Cancer Society who wants their money to go toward more regulation?

The problem is not with the academic physician. Medical scientists want to do studies. Marching alongside are the patients who are desperate to get new treatments. While many criticize the pharmaceutical industry, it is highly unlikely that these companies wouldn’t relish the opportunity to see their drugs enter the market expeditiously. Standing between patients and better clinical outcomes is the research bureaucracy. Should we fail to arrest the explosive growth in regulatory oversight we will approach a time in the near future when no clinical trials will be conducted whatsoever.

Why Do Cancer Surgeons Cure More Patients Than Medical Oncologists?

Surgery remains the most curative form of cancer treatment. While the reasons for this are many, the most obvious being earlier stage of disease and the better performance status of the patients, there are other factors at work. Surgeons tend to be rugged individualists, prepared to make life and death decisions at a moment’s notice. The surgeon who enters the pelvis expecting an ovarian cyst only to find disseminated ovarian cancer must be prepared to conduct a total hysterectomy and bilateral ovary removal if he/she is to save the patient’s life. It is these types of aggressive interventions that have that revolutionized the treatment of advanced ovarian cancer.

What of the medical oncologists who, with the exception of leukemia and some lymphomas, confront diseases that are difficult to eradicate and for which treatments can be toxic? Trained as incrementalists, they do not expect cures so much as palliation. Their role is not to make hard decisions, but instead to rely upon precedence. Educated in the school of small advances, these physicians are not rewarded for individual successes but they are harshly criticized for any departures from community standards.

Deprived of the opportunity to make bold decisions, medical oncologists follow opinion leaders who instruct them to accrue to standardized protocols. As meaningful advances are few and far between, enormous numbers of patients must be accrued to provide sample sizes with any hope of achieving statistical significance. Among the most disturbing examples of this approach was a trial reported in patients with inoperable pancreatic cancer. The study compared single agent gemcitabine to gemcitabine plus erlotinib. The trial achieved an improvement in survival that led the FDA to approve the two-drug combination. Yet, the actual improvement in median survival was a mere 10 days. The authors beamed, “To our knowledge, this randomized phase III trial is the first to demonstrate statistically significantly improved survival in advanced pancreatic cancer by adding any agent to gemcitabine.” (Moore, MJ et al J Clin Oncol, 2007). To the average observer however, a clinical trial that required 569 patients to improve median survival from 5.91 months to 6.24 months (10 days) would hardly seem cause for celebration.

Medical oncologists have become so accustomed to these marginal advances that they are unmoved to depart from standard protocols lest they be accused of breeching guidelines. This might be acceptable if chemotherapy provided meaningful benefits, but the extremely modest advantages provided by even the best clinical trials scream for medical oncologists to think, well, more like surgeons.

While community oncologists think it heresy to step around a National Comprehensive Cancer Network (NCCN) guideline, investigators at the best institutions, the opinion leaders, have begun to question the merit of blind protocol accrual and come to recognize that many critical questions cannot be easily answered through the current trial process. Questions such as the role of liver resection for colon cancer patients with disease spread to the liver or the role of additional chemotherapy after that liver surgery, simply may not lend themselves to randomized trials. In a review of the topic by one of the leading investigators in the field, Dr. Nancy Kemeny from Memorial Sloan-Kettering in New York examined this dilemma, “The management plan for each patient should be decided by a multidisciplinary team, it may not be possible or ethically defensible to perform large randomized adjuvant trials comparing chemotherapy with surgery alone or comparing modern chemotherapy with older regimens. It may be reasonable to extrapolate from adjuvant trials and meta-analyses showing predominantly disease-free survival benefit. Each decision on postoperative chemotherapy should be viewed in context of prior treatment, surgical preference and individual patient characteristics.”

How refreshing. Finally a clinical investigator has recognized that patients must be managed on an “individual basis” regardless of what the clinical trial data does or does not support.

The concept of personalized medicine flies in the face of contemporary guideline driven treatment. Individualized care is on a collision course with the NCCN. It is time for medical oncologists to reclaim the high ground in doing what is right for patients, using resources that enable them to make smart decisions and to eschew standardized care. In cancer, the dictum “one size fits all” is more accurately “one size fits none.”

Triple Negative Breast Cancer: Worse or Just Different?

The term “triple negative breast cancer” (TNBC) is applied to a subtype of breast cancers that do not express the estrogen or progesterone receptors. Nor do they overexpress the HER2 gene. This disease constitutes 15 – 20 percent of all breast cancers and has a predisposition for younger women, particularly those of black and Hispanic origin. This disease may becoming more common; although, this could reflect the greater awareness and recognition of this disease as a distinct biological entity.

On molecular profiling, TNBC has distinct features on heat maps. The usual hormone response elements are deficient, while a number of proliferation markers are upregulated.  Not surprisingly, this disease does not respond to the usual forms of therapy like Tamoxifen and the other selective estrogen response modifiers known as SERMs. Nonetheless, TNBC can be quite sensitive to cytotoxic chemotherapy. Indeed, the responsiveness to chemotherapy can provide these patients with complete remissions. Unfortunately, the disease can recur. Complete remission maintained over the first three to five years is associated with a favorable prognosis, with recurrence rates diminishing over time and late recurrences more often seen in estrogen receptor-positive cancers.

Triple negative breast cancer is not one, but many diseases.

MTOR-pathway-ger Among the subtypes are those that respond to metabolic inhibitors such as the PI3K and mTOR directed drugs. Another subset may respond to drugs that target epidermal growth factor. There are basal-types that may be somewhat more refractory to therapy, while a subset may have biology related to the BRCA mutants, characterized by DNA repair deficiencies and exquisite sensitivity to Cisplatin-based therapies. Finally, a last group is associated with androgen signaling and may respond to drugs that target the androgen receptor.

Some years ago, we used the EVA-PCD platform to study refractory patients with breast cancer and identified exquisite sensitivity to the combination of Cisplatin plus Gemcitabine in this patient group. We published our observations in the Journal of Clinical Oncology and the combination of Cisplatin or Carboplatin plus Gemcitabine has become an established part of the armamentarium in these patients.

The I-SPY-2 trial has now used genomic analyses confirming our observations for the role of platins in TNBC. This iSignal_transduction_pathways.svgn part reflects the DNA repair deficiency subtype associated with the BRCA-like biology. More recently, we have examined TNBC patients for their sensitivity to novel therapeutic interventions. Among them, the PI3K and mTOR inhibitors, as well as the glucose metabolism pathway inhibitors like Metformin. Additional classes of drugs that are revealing activity are the cyclin-dependent kinase inhibitors, some of which are moving forward through clinical trials.

One feature of triple negative breast cancer is avid uptake on PET scan. This reflects, in part, the proliferation rate of these tumors, but may also reflect metabolic changes associated with altered glucose metabolism. In this regard, the use of drugs that change mitochondrial function may be particularly active. Metformin, a member of the biguanide family influences mitochondrial metabolism at the level of AMP kinase. The activity of Metformin and related classes of drugs in triple negative breast cancer is a fertile area of investigation that we and others are pursuing.

When we examine the good response of many triple negative breast cancers to appropriately selected therapies, the potential for durable complete remissions and the distinctly different biology that TNBC represents, the question arises whether TNBC is actually a worse diagnosis, or simply a different entity that requires different thinking. We have been very impressed by the good outcome of some of our triple negative breast cancer patients and believe this a very fertile area for additional investigation

Cancer Survival and Matrimony: A Marriage Made In Heaven

JCO coverThe November 1, 2013 issue of the Journal of Clinical Oncology (Marital Status and Survival in Patients with Cancer, Aizer, A. et al J Clin Oncol, 2013), reports a study by investigators from Harvard University. Using the Surveillance, Epidemiology and End Results (SEER) data they examined more than 1.2 million cancer patients diagnosed between 2004 and 2008 to measure the impact of marital status on overall survival. Results reveal a statistically significant impact of marriage on cancer survival. The benefit slightly favored males over female, but remained significant across different diseases and for never married, separated, divorced or widowed. The authors note, “The survival benefit associated with marriage was larger than the published survival benefit of chemotherapy.”

Epidemiologic studies that correlate disease states with socioeconomic status, level of education, geographic location, lifestyle or diet are fraught with confounding variables. Nonetheless, well-done studies can open a wealth of interesting questions regarding non-treatment related aspects of our health and well-being. This study is provocative for it identifies the interaction between marital status and stage at diagnosis, as well as overall survival.

There are many ways one might interpret the findings. The accompanying editorial (Marriage Is as Protective as Chemotherapy in Cancer Care, Kissane, D) notes that non-married status may reflect “reduced adherence to state-of-the-art treatment.” That, we presume, would include such variables as regular physicals, frequency of mammograms, PSA evaluations, willingness to undergo surgery or the use of adjuvant treatments. The role of depression is also noted. While all of these may apply, they have a self-serving ring, whereby good health, it would seem, can only be attributed to good doctoring. Controversies surrounding PSA screening or the impact of “annual physicals” on general health are but a few examples where more may not necessarily be better.

While it may be argued that unmarried individuals fail to obtain adequate medical care, the data may reflect somethinAA010368g more profound, the psychoneuroimmunology of cancer survivorship. That is, each patient’s capacity to will-themselves better. The will-to-live is enhanced by close human relationships. We are all witness to patients who survive against all odds. They are usually filled with zeal, willing to go to whatever lengths are required to overcome their illness and most have close interpersonal relationships, nurturing environments, loving families or husbands and wives who dote on them.

Norman Cousins spoke at length about the healing force of one’s emotional and spiritual belief systems in his own battle with ankylosing spondylitis (Anatomy of An Illness, As Perceived by the Patient, 1979). Might his experience reflect a similar dynamic to that described in the current study? My patient Alan Kapuler’s excellent outcome over Non-Hodgkin’s lymphoma, described in my book (Outliving Cancer, 2013, chapter 12) exemplifies this same mind-over-matter dedication, characteristic of many of our long-term survivors.

I applaud Dr. Aizer and his co- investigators for examining this aspect of cancer survivorship. I am impressed that such a report would find its way onto the pages of the Journal of Clinical Oncology. However, I am less certain that these good outcomes reflect state-of-the-art treatment and more of the opinion that married patients may be part of a happier, healthier, better adjusted and more humanly connected population. Interpersonal relationships are not devices. They cannot be patented or sold. However, as can be seen from this study, they may be among the most powerful interventions at our disposal in the management of advanced cancer.

Cancer Patients Who Get Better, Get Better

JCO coverA study published in the October 20 Journal of Clinical Oncology (Use of early tumor shrinkage to predict long-term outcome in metastatic colorectal cancer treated with Cetuximab, Piessevaux H. et al, 31:3764-3775,2013) described “early tumor shrinkage” as a predictor of long-term survival in patients with metastatic colorectal cancer. These Belgian and German investigators re-analyzed two large clinical trials in colon cancer, CRYSTAL and OPUS, to evaluate the impact of early tumor shrinkage at eight weeks of therapy. Both studies were in patients with wild type (non-mutated) KRAS colon cancer who received chemotherapy with or without the monoclonal antibody Cetuximab.

They used a cutoff of 20 percent tumor shrinkage at eight weeks to separate “early responders” from “non-responders.” Early responders were found to have a significantly better survival. The accompanying editorial by Jeffrey Oxnard and Lawrence Schwartz (Response phenotype as a predictive biomarker to guide treatment with targeted therapies, J Clin Oncol 31:3739-3741, 2013) examined the implications of this study.

The measurement of tumor response has been a lynchpin of cancer therapeutics for decades. This was later refined under what is known as RECIST (Response Evaluation Criteria In Solid Tumors) criteria. Despite this, there remained controversy regarding the impact of early response on long term survival. The current Piessevaux trial however, is only the most recent addition to a long history of studies that established the correlation between tumor shrinkage and survival. Earlier studies in colorectal, kidney, esophagus and lung cancers have all shown that early response correlates with superior outcomes.

What is gratifying in the accompanying editorial is the discussion of the “response phenotype” as a predictor of survival. Phenotype, defined as “the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment” reflects the totality of human biology not just its informatics (genotype). This renewed appreciation of tumor phenotype in oncology is important for it re-focuses on tumor biology over tumor genetics.

The  ex-vivo analysis of programmed cell death (EVA-PCD) that we utilize, is itself a phenotypic platform that measures actual cellular behavior, not gene profiles, to gauge drug sensitivity. We have previously shown that the measurement of chemotherapy effect on human tumor tissue predicts response, time to progression and survival. The current study used clinical response (early tumor shrinkage) to successfully measure the same.

This analysis of early response by Piessevaux is bringing our most sophisticated investigators back to what they should have known all along.
1. Responding patients do better than non-responding patients.
2. Early measurement of response is predictive of long term outcome.
3. These measurements can and should be done in the laboratory.

Taken together, the current study supports early tumor shrinkage and by inference, ex vivo analyses, as important predictors of patient response and survival.

Of Prostate Cancer, Glucose, Metabolism and Metformin

A study conducted by Canadian investigators and reported in the September 1, 2013 issue of the Journal of Clinical Oncology examined the impact of Metformin use on mortality in men with diabetes and prostate cancer (Margel D. Urbach DR., Lipscombe LL, Metformin Use and All-Cause and Prostate Cancer-Specific Mortality Among Men with Diabetes, Journal of Clinical Oncology, volume 31, #25, pgs 3069-3075, 2013). The investigators examined 3837 patient with a median age of 75 years. They conducted a retrospective analysis examining the Ontario Province heath care records. The intent was to examine duration of exposure to Metformin as a diabetes management in patients with prostate cancer to assess the impact on all-cause and prostate cancer-specific mortality.

The results are impressive and instructive. There was a significant decrease in the risk of prostate cancer-specific and all-cause mortality, which related to the dose and duration of exposure to Metformin. The adjusted hazard ratio for the study of 0.76 indicates that there is a 24% reduction in mortality for prostate cancer-specific events with the use of Metformin. This study was not perfect, as it was retrospective, there was no randomization and it was impossible to control for all other variables such as exercise, smoking history and clinical parameters of prostate cancer. Nonetheless, there is a clear and important trend toward reduced prostate cancer and even overall mortality. This is but one of a series of clinical studies that have examined the impact of Metformin upon not only prostate cancer but also breast cancer. Much of this work was originally pioneered by Dr. Michael Pollack from McGill University in Montreal.

The biguanide class of antidiabetic drugs, originates from the French lilac or goat's rue (Galega officinalis), a plant used in folk medicine for several centuries.  (Wikipedia)

The biguanide class of antidiabetic drugs, originates from the French lilac or goat’s rue (Galega officinalis). (Wikipedia)

Metformin and the closely related Phenformin are members of the class of drugs known as biguanides. While the exact mode of action of the biguanides is not fully understood, they are known to disrupt mitochondrial respiration at complex I. This upregulates an enzyme known as adenosine monophosphate kinase (AMPK) thereby altering energy metabolism within the cell and down regulating mTOR. In diabetics, this drives down blood glucose to control the disease. However, in cancer patients, a profound effect is observed that suppresses synthetic pathways necessary for energy metabolism, cellular survival and cellular proliferation. These effects appear responsible for the impact upon prostate cancer. Interestingly, these drugs are more effective in controlling already transformed cells and less effective in the prevention of cancer. This is consistent with the observation that malignantly transformed cells change their state of metabolism.

This article is interesting on many levels. The first and most obvious is that this relatively inexpensive and well-tolerated drug can have an impact on prostate cancer.

Secondly, these effects appear to cross the lines of different cancer types, such that breast cancer and other forms of cancer might also be successfully treated.

The third note of interest shows that even patients without diabetes can tolerate Metformin, suggesting this as an adjunct to many different treatments. Finally and most importantly this represents the new and important recognition that cancer is not a genomic disorder, but a metabolic disorder. Cancer may utilize normal genetic elements to its own advantage. AMP kinase, LKB1 and mTOR are not unique to cancer, but instead, are found in every cell. These normal proteins are simply altered in their function in malignantly transformed cells. Metformin is one of what will soon be a large number of metabolomic agents entering the clinical arena as cancer research moves from the nucleus to the mitochondrion.

The Tumor Micro Environment

As I was reading the October 1 issue of the Journal of Clinical Oncology, past the pages of advertisement by gene profiling companies, I came upon an article of very real interest.

While most scientists continue to focus on cancer-gene analyses, a report in this issue from a collaboration between American and European investigators provided compelling evidence for the role of tumor associated inflammatory cells in metastatic human cancer. (Asgharzadeh, S J Clin Oncol 30 (28)3525–3532 Oct 1, 2012) Through the analysis of children with metastatic neuroblastoma, they found that the degree of infiltration into the tumor environment by macrophages had a profound effect upon clinical outcome. This study confirmed earlier reports that macrophage infiltration is an integral part and potential driver of the malignant process.

Using immunohistochemistry and light microscopy the investigators scored patients for the number of CD163(+) macrophages, representing the alternatively activated (M2) subset within the tumor tissue. They then examined inflammation related gene expressions to develop a “high” risk, “low” risk algorithm and applied it to the progression free survival in these children.

Highly significant differences were observed between the two groups. This report adds to a growing body of literature that describes the interplay between cancer cells and their microenvironment. Similar studies in breast cancer, melanoma and multiple myeloma have shown that tumor cells “co-opt” their non-malignant counterparts as they drive transformation from benign to malignant, from in-situ to invasive and from localized disease to metastatic. These same forces have the potential to strongly influence cellular responses to stressors like chemotherapy and growth factor withdrawal. While we may now be on the verge of identifying these tumor attributes and characterizing their impact upon survival, these analyses represent little more than increasingly sophisticated prognostics.

The task at hand remains the elucidation of those attributes and features that characterize each patient’s tumor response to injury toward ultimate therapeutic response. To address this level of complexity, we need the guidance of more global measures of human tumor biology, measures that incorporate the dynamic interplay between tumors cells, their stroma, vasculature and the inflammatory environment.  These are the “real-time” insights that can only be achieved using human tissue in its native state. Ex vivo analyses offer these insights. Their information moves us from the realm of prognostics to one of predictives, and it is after all predictive measures that our patients are most desperately in need of today.