Dr. Maha Hussain, an oncologist who was one of 4 out of 17 members of the FDA Advisory Committee to vote against accepting against the company’s claim to efficacy for Provenge (Sipuleucel-T) prostate cancer vaccine, is calling for an expanded access program to empower patients who want and need it to receive the drug while an ongoing 500 man clinical trial of Provenge is completed.

Reviewing Proveng’s chances of FDA approval from the point of view of investors, Matthew Herper gives an overview useful for patients as well. Herper writes:

The FDA has a legal deadline of May 15 to make a decision–although it is possible to break or extend it. But buying the stock in front of this deadline is probably highly risky. There is a reasonable chance the FDA will decide to go against the panel vote and ask for more data. And the downside to the stock if the FDA does delay approval by asking Dendreon for more data is probably much bigger than any potential gain.

This is the text of Howard Scher M.D.’s letter to FDA about the March 29th advisory committee hearing on Dendreon’s vaccine Sipuleucel-T (Provenge):

I am writing to express concerns about the recent review of Sipuleucel-T at the FDA Advisory Meeting on March 29, 2007. These concerns are: a recommendation for approval based on data that fall short of the regulatory requirements; an inadequate statistical construct to determine definitive benefit; incomplete data on product safety; and what appear to be different criteria for approval by two Advisory Committees to the Agency.

A week before the FDA advisory committee meeting on Dendreon’s Provenge, investment analyst Adam Feuerstein predicted that if Provenge is approved it could generate over $100 million in sales in 2008. Feuerstein’s estimate is based on a projected price of $30,000 per year per course of the vaccine. His model assumes increasing numbers of men living with (and dying of) metastatic androgen independent refractory prostate cancer (AIPrC) over the next decade.

For an overview of 3 main types of immunotherapies, or therapeutic vaccines, in trials for prostate cancer see Round Table meeting held on April 1, 2005 in Boston, Massachusetts. This meeting was paid for by Cell Genesys. Contents (with charts and explanatory cartoons):

FUNDAMENTALS OF TUMOR IMMUNOLOGY
RELEVANT TO PROSTATE CANCER IMMUNOTHERAPY
Charles G. Drake, MD, PhD
The Sidney Kimmell Comprehensive Cancer Center Johns Hopkins Medical Center

POXVIRUS VACCINES
Robert S. DiPaola, MD
The Cancer Institute of New Jersey

TUMOR CELL VACCINES
Jonathan Simons, MD
Emory University School of Medicine

DENDRITIC CELL VACCINES
Johannes Vieweg, MD
Duke University Medical Center

Cell Genesys says the 22 patients in their Phase 2 trial of GVAX who received the most effective tolerable dose — “the dose that is comparable to that being employed in the company’s ongoing Phase 3 program”– reached median survival of 35.0 months.

This trial enrolled men with hormone refractory prostate cancer. Cell Genesys previously reported final median survival results from its first multi-center Phase 2 trial of GVAX as 26.2 months.

“The survival results from the two, independent multi-center Phase 2 clinical trials compare favorably to the previously published median survival of 18.9 months for metastatic hormone-refractory prostate cancer patients treated with Taxotere(R) (docetaxel) chemotherapy plus prednisone, the current standard of care for these patients. The company’s ongoing Phase 3 program is designed to confirm this potential survival benefit for GVAX immunotherapy for prostate cancer.”

Read the full press release