With an EVA-PCD Assay, It Can Be That Simple

Shortly after I left the university and joined a medical oncology group, one of the junior members of the practice asked if I would cover for him during his summer vacation. Among the patients he signed over to me was a gentleman in his 60s with what he described as “end-stage” chronic lymphocytic leukemia (CLL). As the patient had already received the standard therapies, second line regimens and experimental drugs available at the time, the physician had run out of options. My charge was to keep him comfortable. I asked if it would be all right for me to study his cells in my lab and the doctor agreed.

CLL 130611.06I met the patient the next day. He was a very pleasant tall, slender black man lying in bed. He had lost a great deal of weight making the already enlarged lymph nodes in his neck appear that much more prominent. As I was engaged in the study of CLL as my principal tumor model, I asked if I might examine his circulating CLL cells as part of our IRB-approved protocol. He graciously obliged and I obtained a few ccs of blood. We were deeply ensconced in tumor biology analyses and his cells were used to explore membrane potentials, DNA degradation and glutathione metabolism as correlates with drug response profiles by EVA-PCD analysis. A large number of those studies have since been published.

What struck me about the patient’s EVA-PCD profile was the exquisite sensitivity to corticosteroids. Corticosteroids in the form of prednisone, Medrol, Solu-Medrol and Decadron are the mainstays of therapy for lymphoid malignancies like CLL. Everyone receives them. Indeed this patient had received them repeatedly including his first line chlorambucil plus prednisone, his second-line CHOP and his third line ESHAP. It was only after he had failed all of these increasingly intensive regimens that he finally moved on to an experimental agent, homoharringtonine, a drug that finally received FDA approval in 2012, after almost 40 years of clinical development. Unfortunately for him homoharringtonine did not work and it seemed we were well beyond conventional therapies, or were we?

I pondered the corticosteroid sensitivity finding and decided to start the patient on oral prednisone. It would be another two weeks before his physician returned and there really weren’t many options. The patient responded overnight. The lymph nodes melted away. The spleen diminished. He began to eat and gained weight. Within a few days he felt well enough to go home. I discharged the patient and remember writing his prednisone prescription, 40 mg by mouth each morning.

A week later, my colleague returned from his retreat in the Adirondacks. He inquired about his patients and surmised that this gentleman, no longer in the hospital, had died. I explained that he had been discharged.

“Discharged . . . how?” he asked. I described the findings of our EVA-PCD study, the sensitivity to steroids and the patient’s miraculous clinical response to this, the simplest of all possible treatments. The physician then turned to me and said “Prednisone . . . hmmm . . . I could have done that.”

I am reminded of this story almost daily. It is emblematic of our work and of those who choose not to use it. Good outcomes in cancer do not occur by chance. They also do not require blockbuster new drugs or brilliant doctors. They require individualized attention to the needs of each patient.

A recurring theme, exemplified by this patient among others, is that cancer cells can only defend themselves in a limited number of ways. Once a selection pressure, in a Darwinian sense, is removed (e.g. corticosteroids were not used during the homoharringtonine treatments) the surviving cells, sensitive to steroids, re-emerge to be identified and captured in our laboratory platform.

It is remarkable how often heavily pretreated patients with ovarian cancer are found sensitive to Taxol after they had received it years earlier, but not since; or breast cancer patients who fail every new agent only to prove responsive to CMF, the earliest of all of the breast cancer drug combinations developed in the 1970s. Our job as oncologists is to find those chinks in armor of cancer cells and exploit them. The EVA-PCD platform, in the eyes of some, may not be groundbreaking . . . it just happens to work!


Chronic Lymphocytic Leukemia (CLL) as a Platform for Functional Profiling

Among the most common forms of leukemia in adults is chronic lymphocytic leukemia. This neoplasm usually arises in a subset of lymphocytes known as B-cells. However, T-cell variants also occur. The disease presents clinically as an elevation of the circulating lymphocytes. This may be associated with enlarged lymph nodes, splenomegaly or liver enlargement.

The decision to treat patients is largely based upon clinical staging systems know as the Rai or Binet classifications. Low risk patients can often be observed without treatment, while more aggressive presentations (such as those associated with anemia and low platelet counts) require intervention. More recently, molecular determinants of aggressiveness have been applied in the prognosis of this disease. These include: CD38, VH gene mutation and Zap 70. Additional findings include ATM mutations, principally in the T-cell and pro-lymphocytic variants.

For more than 40 years, the treatment of choice for this disease was oral chlorambucil. Although effective, chlorambucil resulted in the development of resistance and was associated with rather significant myelosuppression over time. The introduction of fludarabine (FAMP) and 2-CDA revolutionized the management of this disease —providing high response rates with relatively tolerable toxicities.

The introduction of 2-CDA and fludarabine in the 1980s offered an opportunity for our laboratory to examine drug interactions in CLL patients. Combining the alkylating agents (of which, chlorambucil is a member) with 2-CDA revealed synergy (supra-additvity) in 100 percent of the CLL samples we studied (Nagourney, R; et al. British Journal of Cancer, 1993). Based on this observation, we began treating patients with CLL and related lymphoid malignancies with a combination of Cytoxan and 2-CDA, resulting in dramatic and durable remissions.

O’Brian, Keating and other investigators at the MD Anderson then undertook this work (using fludarabine), providing for the most effective therapy for CLL in today’s literature. Unfortunately, a percentage of patients who receive this combination develop deep myelo-suppression. Therefore, the administration of this combination requires careful monitoring by the physician.

One of the most interesting aspects of the high activity observed for fludarabine was the capacity of this “anti-metabolite” to induce cell death in short term cultures of CLL cells. It was well known that CLL cells were not highly proliferative, yet the anti-metabolite class of drugs was specifically designed to stop cell proliferation at the level of DNA synthesis. We realized that 2-CDA and Fludarabine had to be killing cells, not preventing their growth. This conundrum provided an opportunity for us to test a related anti-metabolite in this disease. We chose cytarabine (Ara-C), a drug not considered effective for CLL (e.g. low proliferative rate, no likelihood of DNA synthesis inhibition, no likelihood of cytotoxicity). To our delight, low doses or Ara-C proved highly effective in controlling even the most advanced cases of CLL as we then reported.

CLL became one of our favored models for the study of human tumor biology, enabling us to study drug responses at the molecular level. Many of the observations that we made in this hematologic malignancy granted us insights that we continue to apply in solid tumors today.