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to work in a different way. Dendreon’s treatment, sipuleucel-T (Provenge), is an infusion-based medicine that is supposed to stimulate a patient’s immune system to recognize prostate cancer cells and fight them. Johnson & Johnson’s abiraterone (Zytiga) is an oral pill that’s designed to interfere with the body’s synthesis of androgens—the male sex hormones that help drive growth of prostate cancer. Medivation’s drug, also an oral pill, seeks to block the binding of androgens to the androgen receptor, which is supposed to interfere with a key process that drives tumor cell growth.
Medivation got ahold of this compound by licensing it in 2005 from the lab of Charles Sawyers, the prominent cancer researcher at Memorial Sloan-Kettering Cancer Center in New York. Like many cancer drug developers, Medivation’s strategy to bring the drug to the market was to study it first in the sickest of the sick, where the need for a new therapy was greatest. But just like most any cancer drug developer, Medivation is working its way forward into patients with less severe forms of the disease. The next big test is among 1,680 patients, in a study with the rather confident title of Prevail. That study will enroll patients whose disease has spread, and which no longer responds to traditional chemical-castration therapy, but who haven’t yet gone all the way to get last-ditch chemo. This is the so-called “pre-chemo” patient population that Dendreon is attempting to serve, and the same group of patients Johnson & Johnson is hoping to reach with its drug. J&J plans to release clinical results of a 1,088-patient at the upcoming ASCO meeting, which it has said were encouraging enough to form the basis of a new application for FDA approval.
With so many drugs new to the market or close to the marketplace, it creates some interesting new possibilities. Dr. de Bono, the lead investigator of Medivation’s Affirm study, said he believes the Medivation drug should work well in combination with J&J’s treatment. By blocking androgen synthesis (J&J), and androgen uptake into cells (Medivation), the hope is to provide a more comprehensive blockade of the substances that nourish prostate tumors. “These drugs have great potential given together. [They are] very different agents that I hope will be complementary,” de Bono says.
Despite the progress in treating prostate cancer, nobody is making claims about having a cure. Tumors are wily creatures, and they often end up finding ways to resist new treatments, a process which isn’t fully understood. One of the critical next questions, de Bono says, is finding out what causes resistance. But given the progress of the past few years with the new drugs, de Bono strikes a very optimistic tone. “We haven’t cured prostate cancer, sadly, although we’re getting there,” he says.