The Frustrating Reality – When a Tumor Sample isn’t Sufficient for Testing

A dying leukemia cell

A dying leukemia cell

The principles underlying the Rational Therapeutics EVA-PCD platform reflect many years of development. Recognizing the importance of cell death measures — apoptotic and non-apoptotic — our laboratory dismissed growth-based assays. The closure of Oncotech, the principal purveyor of proliferation-based assays, illustrates the demise of a failed paradigm in the study and testing of human tumor biology. A second principal of our work is the need to examine all of the operative mechanisms of cell death (autophagic, necrotic, etc.). Laboratories that measure only one mechanism of cell death (e.g. caspase activation as a measure of apoptosis) miss important cell responses that are critical to the accurate prediction of clinical response. The third principle of our work is the maintenance of cells in their native state.

These fundamentals provide the basis of our many successes, but also a constraint. Because we do not propagate, subculture or expand tissues, we can only work with the amounts of tissue provided to us by our surgeons. While some labs propagate small biopsy samples into larger populations by growth to confluence, this introduces irreconcilable artifacts, which diminish the quality of sensitivity profiles. Avoiding this pitfall, however, demands that a tissue sample be large enough (typically 1cm3) to provide an adequate number of cells for study without growth or propagation.

This is the reason our laboratory must request biopsies of adequate size. The old computer dictum of “garbage in, garbage out” is doubly true for small tissue samples. Those that contain too few tumor cells, are contaminated, fibrotic or inadequately processed will not serve the patients who are so desperately in need of therapy selection guidance. As a medical oncologist, I am deeply disappointed by every failed assay and I am more familiar than most with the implications of a patient requiring treatment predicated on little more than intuition or randomization.

We do everything within our power to provide results to our patients. This sometimes requires low yield samples be repeatedly processed. It may also set limitations on the size of the study or, in some circumstances, forces us to report a “no go” (characterized as an assay with insufficient cells or insufficient viability). Of course, it goes without saying that we would never charge a patient for a “no-go” assay beyond a minimal set up fee (if applicable). But, more to the point, we suffer the loss of an opportunity to aid a patient in need.

Cancer patients never undergo therapy without a tissue biopsy. Many have large-volume disease at presentation, so it is virtually always possible to obtain tissue for study if a dedicated team of physicians makes the effort to get it processed and submitted to our laboratory. The time and energy required to conduct an excisional biopsy pales in comparison to the time, energy and lost opportunities associated with months of ineffective, toxic therapy.

Synergistic Drug Combinations Provide Better Outcomes for Cancer Patients

Among the most sought after attributes of chemotherapy drug combinations is drug synergy. Synergy, defined as supra-additivity wherein the whole is greater than the sum of the parts, reflects an elegant interaction between drugs predicated on their modes of action. While some synergistic interactions can be predicted based upon the pharmacology of the agents, others are more obscure.

We have extensively examined the synergy between classes of drugs based on known modes of action. But, in some circumstances, our studies have been purely exploratory. Among our most successful findings have been:

  1. Alkylating agent plus purine analogs (cytoxan & fludarabine)
  2. Platin plus antimetabolites (cisplatin & 5FU; cisplatin & gemcitabine)
  3. Dual antimetabolite combinations (gemcitabine & capecitabine)
  4. Natural products plus anti-metabolite (Doxil & gemcitabine; vinorelbine & capecitabine)

More recently, we have explored the interaction between signal transduction inhibitors. The results of these investigations have been the subject of numerous presentations at international meetings.

The application of synergy analyses may represent one of the most important applications of our functional profiling platform; enabling us to explore both anticipated and unanticipated favorable interactions. Equally important may be our capacity to study drug antagonism wherein two effective drugs counteract each others’ benefits. This phenomenon, characterized by the whole being less than the sum of the parts, represents a major pitfall for clinical trialists who simply combine drugs “because they can.”

These analyses are revolutionizing the way our group applies newer classes of drugs and has the potential to accelerate drug development and clinical therapeutics. Good outcomes require good drugs, but better outcomes require good combinations. Intelligent combinations are a principle focus of the work at Rational Therapeutics. We strive everyday to identify the best outcomes for patients.

Why Hasn’t Functional Profiling Been More Broadly Accepted in the United States?

This is an interesting question. One that my colleagues in the field and I have often pondered. Is it that American medicine is more conservative than European and Asian medicines? Are we late adopters? Do we hold medical tests and treatments to a higher standard? Are American doctors too wedded to protocol therapies? Is it cooperative groups that guide all of our decisions? NCCN guideline? Pharmaceutical marketing?

Or is it possible that a small number of opinion leaders opted out of the field and have done their best to take everyone else with them?

I would say it is the latter.

In some ways, the slow adoption of these techniques — compared with Europe and Asia — does reflect the relative conservatism of American medicine. We have been slow to adopt acupuncture and incorporate diet and lifestyle changes into medical therapy, despite their manifest importance. We are often slower to improve drugs, even when they establish clinical utility in well-conducted foreign trials. So, there may indeed be a component of late adoption and conservatism.

However, The re-importation of technologies is not only seen in the medical community. The early adoption of transistor technology by the Japanese despite their development by American inventors; the late adoption of robotics and fuzzy logic by Americans; and our tardiness in adopting smaller, more fuel-efficient automobiles all illustrate this point. But, the most vexing hurdle of all has been the dismissal by mostly university-based investigators who have weighed in against the adoption of human tissue tests for the prediction of response to chemotherapeutics.

These investigators — who, in aggregate, provide care to less than 10 percent of the cancer patients in need — have an inordinate amount of influence upon the application of novel technologies. In what can only be viewed as a sour grapes phenomenon, many of these physicians even tried to apply early forms of human tumor study in their own labs and medical centers.

The utter failure of the clonogenic assay in the 70s and 80s and related growth-based technologies, poisoned these academics and closed their minds to newer developments based on the modern discoveries of apoptosis and other forms of programmed call death. When we, and our colleagues, reported discoveries using these more modern endpoints, the academic community turned a deaf ear. As our data improved, they dug in their heels. And when the data rose to the level of the best peer reviewed journals in the field, the critics became ever more vocal.

We can now thank these “scientists” for putting the United States behind Europe and Asia in the adoption of these important methodologies. While patients in America must struggle with their physicians to get ex-vivo analyses conducted, children in Europe with leukemia have immediate access to these tests. Adults in England with leukemia can all request these assays, German patients regularly take advantage of assay methodologies. And the Japanese often apply related techniques for the treatment of their solid tumors.

Not unlike robotics, total quality management and fuel-efficient automobiles, the Americans (who invented in vitro chemosensitivity testing) will again be importing the technology that they are responsible for developing.

The Role of the Platinum Derivatives in Cancer Therapy

The discovery of cisplatinum and the subsequent development of its derivatives (carboplatin and oxaliplatin) represent an interesting saga in modern oncology. When Rosenberg observed in 1960s that platinum electrodes in salt water baths inhibited the growth of bacteria and fungi it lead to the isolation of cis-dichloro diamine platinum (cisplatin). Its application in testicular cancer provided a dramatic leap forward for this heretofore-lethal disease. Subsequent applications in ovary and lung cancers lead to some of the most effective therapies in modern oncology. Although the exact mechanisms of action continue to be investigated, the platination of guanine residues in DNA constitutes the principle mechanism of cytotoxicity.

The use of the human tumor laboratory model has provided us the luxury of exploring the platinum drugs in a wide variety of diseases. Among our published discoveries has been the relative equivalence of the platinum derivatives, as well as their profound synergy with agents like gemcitabine. It is of significant interest that this broadly effective class of compounds — extensively applied in the treatment of lung, colorectal, ovarian and breast cancers, as well as others — remains less active in the hematologic neoplasms. This is in striking counter distinction to nearly all other classes of chemotherapeutics.

Among our most gratifying observations, from the early 1990s, was the clear and profound activity of the platinum derivatives in breast cancers. We feel that our discoveries, outlined in an editorial published in 2000 (The Once and Future Role of Platinum Agents in Advanced Breast Cancer), in no small part have influenced the broad application of platinum in modern breast cancer management.

It was not genius or divine intervention that lead us to these important discoveries, but, quite simply, the use of a validated human tumor model that accurately probed tumor types, leading us to these findings. It is virtually impossible for an unbiased observer to review these contributions and not recognize that the human tumor model has been the conduit by which these discoveries were made.

The proper study of human cancer is human cancer. Our results speak for themselves when it comes to ovarian, breast and hematologic neoplasms, treatments for which can be traced directly to our laboratories.

What Can We Offer Patients With Pancreatic Cancer?

Recently, I received a call from a previous patient for whom I was not the treating oncologist.  Originally, she had heard about our work on a radio interview and asked her physician in Ohio to send a sample to our laboratory. The results of her assay concluded that a three-drug combination (cisplatin plus Taxol plus gemcitabine) — not commonly used in a pancreatic cancer — was her best option.

Unbeknownst to me, after beginning therapy, the patient had a prompt and dramatic response. When the patient recently contacted me, I cursorily examined the chart prior to our discussion and noted the date of June 24. At first, I thought the patient was showing evidence of progression barely two months after our analysis. Recognizing that no test is perfect and that even our best recommendations may not work, I contacted the patient to discuss her case. It was only then that I realized that indeed the assay data was from 14 months ago and that her response had been excellent for more than a year.

After congratulating the patient on her good outcome and discussing modifications in her therapy (predicated on some x-ray findings of early progression) I asked what her physician’s reaction to the good result had been. The response was muted. Indeed, the physician, having witnessed a rather remarkably good response, only commented that she knew the patient wouldn’t be cured. Recognizing that metastatic pancreatic cancer has an objective response rate measured in single digits and a median overall survival of 4-6 months, I was disappointed to realize that a patient who was well 14 months after diagnosis didn’t seem to impress the treating oncologist.

We are now engaged in reviewing the patient’s diagnostic studies to determine if the EVA-PCD findings will provide information to further guide therapy. While I was very realistic with the patient — explaining that there is no certainty that further benefit can be obtained — there are, in fact, a number of drugs that could hold benefit for the patient. These including: erlotinib, irinotecan and a number of novel combinations. We will be interested to see if further good results can be obtained and are gratified by the patient’s good outcome to date.

National Cancer Institute Stops Gene-based Clinical Trials – Part 2

Last week we discussed the National Cancer Institute’s suspension of three ongoing clinical trails using genomic platforms to select therapies for cancer patients. This week, we seek to answer the question: What went wrong?

The simple answer is that cancer isn’t simple.

Cancer dynamics are not linear. Cancer biology does not conform to the dictates of molecular biologists. Once again, we are forced to confront the realization that genotype does not equal phenotype.

In a nutshell, cancer cells utilize cross talk and redundancy to circumvent therapies. They back up, zig-zag and move in reverse, regardless of what the sign posts say. Using genomic signatures to predict response is like saying that Dr. Seuss and Shakespeare are truly the same because they use the same words. The building blocks of human biology are carefully construed into the complexities that we recognize as human beings. However appealing gene profiling may appear to those engaged in this field (such as Response Genetics, Caris, the group from Duke and many others) it will be years, perhaps decades, before these profiles can approximate the vagaries of human cancer.

Functional analyses like the EVA-PCD platform, which measure biological signals rather than DNA indicators, will continue to provide clinically validated information and play an important role in cancer drug selection. The data that support functional analyses is demonstrably greater and more compelling than any data currently generated from DNA analyses.