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

An 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 your 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.

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.

Toward A 100% Response Rate in Human Cancer

Oncologists confront numerous hurdles as they attempt to apply the new cancer prognostic and predictive tests. Among them are the complexities of gene arrays that introduce practicing physicians to an entirely new lexicon of terms like “splice variant, gene-rearrangement, amplification and SNP.”

Although these phrases may roll of the tongue of the average molecular biologists (mostly PhDs), they are foreign and opaque to the average oncologist (mostly MDs). To address this communication shortfall laboratory service providers provide written addenda (some quite verbose) to clarify and illuminate the material. Some institutions have taken to convening “molecular tumor boards” where physicians most adept at genomics serve as “translators.” Increasingly, organizations like ASCO offer symposia on modern gene science to the rank and file, a sort of Cancer Genomics for Dummies. If we continue down this path, oncologists may soon know more but understand less than any other medical sub-specialists.

However well intended these educational efforts may be, none of them are prepared to address the more fundamental question: How well do genomic profiles actually predict response? This broader issue lays bare our tendency to confuse data with results and big data with big results. To wit, we must remember that our DNA, originally provided to each of us in the form of a single cell (the fertilized ovum) carries all of the genetic information that makes us, us. From the hair follicles on our heads to the acid secreting cells in our stomach, every cell in our body carries exactly the same genetic data neatly scripted onto our nuclear hard-drives.

What makes this all work, however, isn’t the DNA on the hard drive, but instead the software that judiciously extracts exactly what it needs, exactly when it needs it. It’s this next level of complexity that makes us who we are. While it is true that you can’t grow hair or secrete stomach acid without the requisite DNA, simply having that DNA does not mean you will grow hair or make acid. Our growing reliance upon informatics has created a “forest for the trees” scenario, focusing our gaze upon nearby details at the expense of larger trends and insights.

What is desperately needed is a better approximation of the next level of complexity. In biology that moves us from the genotype (informatics) to the phenotype (function). To achieve this, our group now regularly combines genomic, transcriptomic or proteomic information with functional analyses. This enables us to interrogate whether the presence or absence of a gene, transcript or protein will actually confer that behavior or response at the system level.

I firmly believe that the future of cancer therapeutics will combine genomic, transcriptomic and/or proteomic analyses with functional (phenotypic) analyses.

Recent experiences come to mind. A charming patient in her 50s underwent a genomic analysis that identified a PI3K mutation. She sought an opinion. We conducted an EVA-PCD assay on biopsied tissue that confirmed sensitivity to the drugs that target PI3K. Armed with this information, we administered Everolimus at a fraction of the normal dose. The response was prompt and dramatic with resolution of liver function abnormalities, normalization of her performance status and a quick return to normal activities. A related case occurred in a young man with metastatic colorectal cancer. He had received conventional chemotherapies but at approximately two years out, his disease again began to progress.

A biopsy revealed that despite prior exposure to Cetuximab (the antibody against EGFR) there was persistent activity for the small molecule inhibitor, Erlotinib. Consistent with prior work that we had reported years earlier, we combined Cetuximab with Erlotinib, and the patient responded immediately.

Each of these patients reflects the intelligent application of available technologies. Rather than treat individuals based on the presence of a target, we can now treat based on the presence of a response. The identification of targets and confirmation of response has the potential to achieve ever higher levels of clinical benefit. It may ultimately be possible to find effective treatments for every patient if we employ multi-dimensional analyses that incorporate the results of both genomic and phenotypic platforms.

Every Cancer Patient’s Outcome is Important

Clinical oncologists can be divided into different camps. There are those who see patient outcomes as a means-to-an-end. Each clinical response provides a data point and when those data points reach critical mass they become reportable. These are the trialists. They see the world through a utilitarian lens. They use aggregate data, through sufficient patient accrual, to achieve significance. This, they hope, will lead practice-changing observations. Trialists populate academic centers and an ever-expanding number of “mega medical groups” that are now gobbling up private oncology practices. They apply metrics to gauge success, as their focus has moved away from individual patient needs toward the achievement of a “greater good” for the population as a whole. Statistical significance is the currency of their realm and clinical protocols their preferred tool.

In the other camp reside physicians, that dwindling cadre of doctors whose principal focus is the good response of each individual patient. They are the practitioners who eke out a living in an environment of diminishing returns. Having relinquished both autonomy and income over recent years, their one remaining reward is the benefit they can bring to each patient. With neither the desire nor ability to publish their results, individual patient survival becomes their paramount goal. Their job is to alleviate suffering, provide comfort and sponsor the health of their clients. Patients preparing to meet with a cancer specialist should consider carefully who is treating them – and why.

I was reminded of this when a 48-year-old gentleman recently requested an opinion. He had presented to an emergency room with a month-long history of sharp abdominal pain. The CT scan revealed extensive intra-abdominal disease, which upon endoscopic biopsy, proved to be of gastric (stomach) origin. He was immediately referred to an accomplished university-based clinical investigator for consultation.

Metastatic gastric cancer is a very difficult disease to treat. One bright spot has been the discovery that 20 percent of patients carry an epidermal growth factor receptor (HER-2) mutation that enables them to receive Herceptin-based therapy. As luck would have it, this patient did not carry the HER-2 mutation. The university investigator explained that there were limited treatment options. In light of his metastatic presentation, the doctor felt that aggressive, multi-agent chemotherapy might only engender toxicity. The patient was offered either single agent 5-FU for palliation or the opportunity to participate in a clinical trial. The patient considered his options and chose to seek an opinion with me.

I reviewed the patient’s status and explained that while the opinion of the university investigator was valid it might underestimate the patient’s individual chance of response. I explained that gastric cancer statistics, like all medical statistics, are population based. That is, a 20 percent response rate does not mean that every patient gets 20 percent better, but instead, that 20 out of every 100 respond while 80 do not. Our job was to find out which group he belonged to.

The patient decided to undergo a biopsy and submitted tissue to Rational Therapeutics for EVA-PCD® analysis. The results were strikingly favorable with several drug combinations revealing both activity and synergy. After careful comparison, I recommended the combination of a Cisplatin, Taxotere and 5-FU (DCF), a regimen originally developed at the MD Anderson almost 10 years earlier.

On March 12th, the patient began treatment on an every-other-week schedule. As he did not circulate tumor markers like CEA or CA 19-9, there was no easy measure of his response so I elected to repeat the PET/CT after just two cycles. Much to my delight, the patient had achieved a complete remission with resolution of all measurable disease, including the bulky abdominal masses, numerous lymph nodes and the stomach. As I described the remarkable PET/CT results, the patient’s wife began to weep. Her husband, the father of their two young children, wasn’t dying after all. He was no longer a grim cancer statistic. With mother’s day approaching, this was the first good news that they had received in six months. At once, the patient began to discuss business trips, travel plans and family outings. He breathed a slow sigh of relief as he realized that, once again, he had a life.

Good outcomes, even in the worst diseases, occur in all oncology practices. Every doctor can regale you with the story of a patient who responded beautifully and went on to survive years beyond everyone’s expectations. The reason we remember these stories is because they occur so infrequently. Complete remissions in metastatic gastric cancer are vanishingly rare. That is the reason that the university investigator offered single agent 5-FU. It’s easy, nontoxic, well tolerated, but it also cures no one. The rationale is well established: Why poison patient’s you cannot cure? Playing the averages, this strategy is a winner. Yet, on an individual patient basis it may, in fact, be a very big loser.

What are we to do with the “non-average” patient? What about the outliers? Should we not, at least, try to find them? We do it with stocks, racehorses, Indy-drivers, real-estate investments and every underdog sports team in every league. It’s the outliers after all that we call winners.

Cancer patients are not clinical trial subjects. They are unique individuals with their own very unique biology. Every patient is an experiment in real time, an “N of 1.” We must respect the dignity of each individual and we are duty-bound to apply every tool at our disposal to assist him or her in the pursuit of his or her own very personal best outcome – providing truly personalized cancer treatment. This patient did not have a 20 percent response. Instead, he was one of the fortunate few who responded very well. And for him that response was 100 percent.

Cancer Patients Who Get Better, Get Better

A 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.

Chemosensitivity Testing – What It Is and What It Isn’t

Several weeks ago I was consulted by a young man regarding the management of his heavily pre-treated, widely metastatic rectal carcinoma. Upon review of his records, it was evident that under the care of both community and academic oncologists he had already received most of the active drugs for his diagnosis. Although his liver involvement could easily provide tissue for analysis, I discouraged his pursuit of an assay. Despite this, he and his wife continued to pursue the option.

As I sat across from the patient, with his complicated treatment history in hand, I was forced to admit that he looked the picture of health. Wearing a pork pie hat rakishly tilted over his forehead, I could see few outward signs of the disease that ravaged his body. After a lengthy give and take, I offered to submit his CT scans to our gastrointestinal surgeon for his opinion on the ease with which a biopsy could be obtained. I then dropped a note to the patient’s local oncologist, an accomplished physician who I respected and admired for his practicality and patient advocacy.

A week later, I received a call from the patient’s physician. Though cordial, he was puzzled by my willingness to pursue a biopsy on this heavily treated individual. I explained to him that I was actually not highly motivated to pursue this biopsy, but instead had responded to the patient’s urging me to consider the option. I agreed with the physician that the conventional therapy options were limited but noted that several available drugs might yet have a role in his management including signal transduction inhibitors.

I further explained that some patients develop a process of collateral sensitivity, whereby resistance to one class of drugs (platins, for example) can enhance the efficacy of other class of drugs (such as, antimetabolite) Furthermore, patients may fail a drug, then be treated with several other classes of agents, only then a year of two later, manifest sensitivity to the original drug.

Our conversation then took a surprising turn. First, he told me of his attendance at a dinner meeting, some 25 years earlier, where Dan Von Hoff, MD, had described his experiences with the clonogenic assay. He went on to tell me how that technique had been proven unsuccessful finding a very limited role in the elimination of “inactive” drugs with no capacity to identify “active “drugs. He finished by explaining that these shortcomings were the reason why our studies would be unlikely to provide useful information.

I found myself grasping for a handle on the moment. Here was a colleague, and collaborator, who had heard me speak on the topic a dozen times. I had personally intervened and identified active treatments for several of his patients, treatments that he would have never considered without me. He had invited me to speak at his medical center and spoke glowingly of my skills. And yet, he had no real understanding of what I do. It made me pause and wonder whether the patients and physicians with whom I interact on a daily basis understand the principles of our work. For clarity, in particular for those who may be new to my work, I provide a brief overview.

1.    Cancer patients are highly individual in their response to chemotherapies. This is why each patient must be tested to select the most effective drug regimen.

2.    Today we realize that cancer doesn’t grow too much it dies too little. This is why older growth-based assays didn’t work and why cell-death-based assays do.

3.    Cancer must be tested in their native state with the stromal, vascular and inflammatory elements intact. This is why we use microspheroids isolated directly from patients and do not grow or subculture our specimens.

4.    Predictions of response are not based on arbitrary drug concentrations but instead reflect the careful calibration of in vitro findings against patient outcomes – the all-important clinical database.

5.    We do not conduct drug resistance assays. We conduct drug sensitivity assays. These drug sensitivity assays have been shown statistically significantly to correlate with response, time to progression and survival.

6.    We do not conduct genomic analyses for there are no genomic platforms available today that are capable of reproducing the complexity, cross-talk, redundancy or promiscuity of human tumor biology.

7.    Tumors manifest plasticity that requires iterative studies. Large biopsies and sometimes multiple biopsies must be done to construct effective treatment programs.

8.    With chemotherapy, very often more is not better.

9.    New drugs are not always better drugs.

10.   And finally, cancer drugs do not know what diseases they were invented for.
While we could continue to enumerate the principles that guide our practice, one of the more important principles is humility. Medicine is a humbling experience and cancer medicine even more so. Patients often know more than their doctors give them credit for. Failing to incorporate a patient’s input, experience and wishes into the treatment programs that we design, limits our capacity to provide them the best outcome.

With regard to my colleague who seemed so utterly unfamiliar with these concepts, indeed for a large swath of the oncologic community as a whole, I am reminded of the saying “There’s none so blind as those who will not see.”

Best Chance for Colon Cancer Survival – Don’t Let It Start

Two papers in the February 23, 2012, New England Journal of Medicine reported important findings in the fight against colon cancer. The first paper (Zuber, AG et al; Colonoscopic Polypectomy and Long-Term Prevention of Colorectal Cancer Deaths) conducted by American investigators establishes the benefit of polyp removal in the prevention of death from colorectal cancer. The study conducted upon 2,602 patients who had adenomas removed reveals a 53 percent reduction in mortality from colon cancer compared with the expected death rate from the disease in this population.

To put this into perspective – virtually no intervention in the advanced disease setting provides a survival advantage. The best we can usually do once the disease is established is an improvement in time to progression. When we do observe a true survival advantage it is usually in the range of a few percentage points and never of this magnitude. How might we explain this astonishingly positive result?

One way to view this finding is to reexamine the biology of cancer. One of the leading experts in the field, Bert Vogelstein, MD, from Johns Hopkins, explained colon carcinogenesis as a pattern of gene perturbations starting at atypia, progressing to carcinoma in situ and ending with invasive, metastatic disease. According to Dr. Vogelstein, the average colon cancer found in a patient at the time of colonoscopy has been present in that person’s colon for 27 years. From there it is only a hop, skip and a jump from one-centimeter adenomatous polyp to metastatic (lethal) disease, all playing out over the last three years in the natural history of the disease. Thus, cancer truly is a disease that doesn’t grow too much, but dies too little and interrupting this process while it is still slumbering can, it would seem, lead to cures.

What I find surprising is the success of the strategy. Since it is now well established that cancer can metastasize when it has achieved the rather diminutive proportions of 0.125 cubic centimeters or less and the average polyp can only be detected at one or more cubic centimeters, it is our good fortune that so many cancers chose not to (or could not) metastasize prior to detection. Reading between the lines, those 12 patients who died of colon cancer as opposed to the expected 25.4 are presumably those with early metastasizing disease. The next frontier will be the detection of these cancers when they are teenagers and not 20-somethings. It may be that proteomic analyses will provide an avenue for earlier detection in the future.

The second article is a European study (Quintero, E et al; Colonoscopy versus Fecal Immunohistochemical Testing in Colorectal-Cancer Screening) that compared colonoscopy with fecal blood testing in a large cohort of patients. While the rates of detection for colorectal cancer were similar, the rates of detecting both advanced and early adenomas, favored colonoscopy (p < .001). This study represents an interesting adjunct to the American study described above. Specifically, if the early detection (and removal) of adenomas can confer a survival advantage then it could be argued that colonoscopy by its virtue of it’s higher detection rate of these precancerous adenomas, is the preferred “screening” modality. With over 50,000 deaths attributed to colorectal cancer in the U.S. each year, the public health benefit of colonoscopies becomes an intersecting point of discussion. Until now, fecal occult blood testing yearly or sigmoidoscopies every several years has been considered equivalent to colonoscopies every 10 years starting at age 50. Do we need to move colonoscopies to the front of the line?

What is most interesting about both these reports is the low-tech nature of the study modalities – and the astonishing efficacy of their application. Colonoscopies have been conducted for decades. They are comparatively simple, do not require affymetrix chips, and yet provide demonstrable benefit that appears to exceed anything offered, to date, by the “genomic revolution.” Perhaps we should all keep an open mind about other comparatively low-tech methodologies that can provide survival advantages.

An Ounce of Prevention

Colorectal cancer is among the leading causes of cancer death in the United States. While most patients develop this disease over a period of decades, associated with an accumulation of genetic mutations (elegantly described by Burt Vogelstein, PhD at Johns Hopkins), a small percentage of patients have a genetic predisposition for this cancer. Among these are those people that carry the familial adenomatous polyp syndrome (FAPS) and those who carry mismatch repair mutations know as Lynch syndrome.

It is the latter group who are the subject of a report in the October issue of the English journal Lancet. In this study, known as the CAPP2 trial, patients with Lynch syndrome received either placebo or 600mg of aspirin per day (the equivalent of two tablets). The results reveal a statistically significant reduction of colon cancer that clearly favored the aspirin group.

To put this in perspective, this dramatic improvement in the highest risk population didn’t come about as the result of a new signal transduction inhibitor or a monoclonal antibody. Instead, it came from the simple administration of one of mankind’s earliest medicinal substances. I applaud these English investigators in conducting this study of 861 patients.

What is most laudatory is that the intervention, while highly effective, is so inexpensive. In an era of proprietary medications and the promotion of expensive new interventions, it is indeed refreshing to read the results of a well-conducted study using an intervention available to all.

Data generated more than two decades ago established the benefit of non-steroidal anti-inflammatory drugs like aspirin for the prevention of colorectal cancer. It is gratifying that this simple intervention has additional scientific support both for those with high-risk predisposition, as well as other patients at risk for this relatively common, yet potentially lethal, malignancy.