Do We Already Have the Tools We Need to Cure Cancer?
June 15, 2012 4 Comments
The rapid-fire sequence of the annual American Association of Cancer Research (AACR) meeting, held in May, followed by the annual American Society of Cllinical Oncology (ASCO) meeting, held in June, provides the opportunity to put scientific discoveries into perspective as they find their way from theoretical to practical.
Members of AACR, the basic science organization, ponder deep biological questions. Their spin-offs arrive in the hands of members of ASCO as Phase I and Phase II trials, some of which are then reported at ASCO meetings.
Many of the small molecules my laboratory has studied over the years are now slowly making their way from “Gee Whiz” to clinical therapy. At the ASCO meeting I attended many of the Phase I sessions, where alphabet soup compounds had their first “in-human” trials. As most of these compounds are familiar to me, I was very interested in these early, though highly preliminary, results.
Departing from one Developmental Therapy (Phase I) session, with visions of signal transduction pathways in my head, I attended a poster discussion on triple negative breast cancer. For those of you unfamiliar with the term, it refers to an increasingly common form of breast cancer that doesn’t mark for the usual estrogen, progesterone, or HER-2 features. Often occurring in younger patients, this form of breast cancer can be aggressive and unresponsive to some forms of therapy. Much work has gone into defining sub-types of this disease and slow progress is being made.
As I examined the posters, one caught my eye, “Clinical Characteristics and Chemotherapy Options of Triple Negative Breast Cancer: Role of Classic CMF regimen. (Herr, MH et al, abstract #1053, ASCO 2012.) What these investigators showed in a series of 826 breast cancer patients was that those treated with the oldest drug combination for breast cancer (CMF) did better than those who received the more modern and more intensive anthracycline or taxane-based regimens. CMF, originally developed by Italian investigators in the 1970s, was the principal therapy for this disease for two decades before it was replaced, first by anthracycline and later by taxane-based treatments. What struck me was the unexpected superiority of this old regimen over its more modern, toxic and expensive brethren.
I began to wonder about other modern therapies and their real impact upon cancer outcomes. One study in HER-2 positive patients revealed relative equivalency between weekly taxol, every three-week Taxotere and Abraxane-based therapy. Once again, the cheaper, older, less toxic Taxol regimen proved superior. While most of the attendees at the ASCO meeting were considering how the newest VEGF inhibitor Regorafenib, or the addition of aflibercept, might impact their practices, I was somewhat underwhelmed by the results of these statistically significant, but clinically marginal survival advantages, all associated with great expense.
As I pondered the implications of the CMF results in triple negatives and those of the taxol results in HER-2 positives, I considered other old-fashioned therapies with newfound potential. Among them, losartan, the angiotensin antagonist that influences tumor stroma or the results of an earlier published study that identified intraconazole (a widely available anti-fungal therapy), as an inhibitor of the hedgehog pathway. While the pharmaceutical industry promotes the use of vismodegib, a hedgehog inhibitor for basal cell skin cancer, and dozens of trials examine VEGF and FGF inhibitors, I wondered whether losartan or intraconazole or other simple compounds and combinations might not already provide many of the tools we need. Is it possible that effective treatments for cancer are at hand?
Lacking the tools to decipher the signals and combine the agents to greatest effect, are we destined to continue to blindly administer increasingly expensive, toxic, yet arguably no more effective therapies? With the myriad of drugs and combinations available today, might it be that we “can’t see the forest for the trees.”