Please email ft@pharmawire.com or call us at Americas: +1 212-500-1384 or Europe: + 44 (0)20 7059 6251 for further information on Pharmawire and how to receive more articles like the one below.
--------------------------------------------------------------------------------------------------------
Cell Genesys’ GVAX drug for prostate cancer is drawing skepticism in the physician community even with Phase III testing still under way, and those who say it may hold promise see it working best not alone but as a combination therapy.
Interim results from one of two ongoing Phase III GVAX trials are expected to be available in the first half of next year, and if the final outcome is positive, perhaps more physicians might be persuaded to consider it as an option for patients.
But in the meantime, some doctors said they see little reason to get enthused about GVAX, designed to stimulate the body’s own immune response against a tumor. They had the same general opinion about another immunotherapeutic, Dendreon’s Provenge (sipuleucel-T), though that product and its maker have received a boost this week on positive Phase I data on a breast cancer product created from the same platform, Neuvenge (lapuleucel-T).
Dr Kenneth Peters, a urologist at William Beaumont Hospital in Michigan, agreed that targeting the immune system with therapies is important, but added that he is not yet convinced that GVAX and other immunotherapies “make me feel like we’re there yet” based on data to date. He predicted that “nothing is around the corner” that would make a clinical impact for patients. “The jury is out.”
Dr Matthew Smith, a medical oncologist at Harvard in Massachusetts, said he’s “not particularly” fond of immunotherapies but added that he is “happy to be swayed otherwise.”
California-based Cell Genesys recently completed recruitment of more than 600 advanced prostate cancer patients into VITAL-1, the first of two ongoing Phase III trials of GVAX. A sufficient number of events required for the final analysis are expected sometime in 2009, following an interim analysis expected in the first half of 2008. A second Phase III study, called VITAL-2, also is recruiting about 600 patients. The company plans to update that trial’s timeline later this year, a spokesperson said.
VITAL-1, a multicenter, randomized, controlled study is comparing GVAX to sanofi-aventis’s Taxotere (docetaxel) chemotherapy plus prednisone, the current standard of care in hormone-refractory prostate cancer patients with metastatic disease. Its primary endpoint is an improvement in survival.
In Phase II, GVAX produced a median survival of about 35 months for prostate cancer patients who received doses comparable to the Phase III dose, results that compare favorably to previously published median survival of 18.9 months in these patients treated with Taxotere plus prednisone. GVAX also is in clinical testing for leukemia and pancreatic cancer.
Survival results are “not as striking” for immunotherapies, said Shriv Srivastava, the co-director of the Center for Prostate Disease Research in Maryland, a program run by the US military health system. In light of those results, he said immunotherapy is being explored for use in earlier stages of the disease.
Although Srivastava said there appear to be fewer side effects for immunotherapy compared to chemo and hormonal therapy, “The real effects of these treatments are yet to be established.” He added, “Probably nothing like this would be tried by itself, but in combination with something else . . . I don’t think immunotherapy, at least at this stage, is being thought of as a single therapy.”
Dr Mark Scholz, with Prostate Oncology Specialists in California, said cancer vaccines like GVAX and Provenge have made progress in that they sensitize the immune system to cancer cells. But, he said, the immunotherapy products “haven’t hit it out of the park yet.”
Scholz, who also serves as executive director of the Prostate Cancer Research Institute in California, was far more excited about the possibility of combining immunotherapy with Medarex and Bristol-Myers Squibb’s CTLA-4 inhibitor. “It will take medicines like GVAX and Provenge and make them work infinitely better,” he said, citing a study of Leukine and CTLA-4. “I think it’s absolutely a humongous breakthrough…I have little doubt that CTLA-4 will be a breakthrough product.”
Cell-Genesys and BMS have an ongoing Phase I study of GVAX in combination with ipilimumab, a fully human anti-CTLA-4 antibody. Dendreon is continuing a Phase III trial of Provenge in hopes of satisfying an FDA request for more robust data spelled out in an approvable letter issued in May. That study is on track to complete enrollment this year, and the agency has agreed to accept positive interim findings of Provenge’s impact on survival.
As of June 30, Cell Genesys had about USD 171m in cash, cash equivalents and short-term investments. The company’s market cap is about USD 273m.
--------------------------------------------------------------------------------------------------------
Pharmawire publishes real-time news and data on the most price sensitive issues in the global pharmaceutical market. Built for financial professionals, Pharmawire covers product approvals, litigation, licensing deals and M & A. Pharmawire provides clients with articles such as the one above in real-time via an online platform and personalized email and BlackBerry alerts. For further information on Pharmawire please email ft@pharmawire.com or call us at Americas: +1 212-500-1384 or Europe: + 44 (0)20 7059 6251
