Prostate Cancer Vaccines

The ultimate treatment for prostate cancer may be a cancer vaccine. In a previous blog, I suggested that one may be available soon and that it would be designed to kill malignant prostate cells even if they had metasticized to some site distant from the prostate. The company that seems closest to having an early version is the Dendreon Corporation, in Seattle that is developing PROVENGE that has been in Stage-3 clinical trials for about two years. These numerous trials were significant enough that the U.S. Food and Drug Administration recognized the merits of PROVENGE to stimulate a patient’s own immune system to attack the malignant cells. Here is a quotation from the first part of an announcement, one of several significant ones:

SEATTLE, WA, November 7, 2005 – Dendreon Corporation (Nasdaq: DNDN) today announced that the U.S. Food & Drug Administration (FDA) has granted Fast Track review status to PROVENGE® (sipuleucel-T) for its proposed use in the treatment of asymptomatic men with metastatic, androgen-independent prostate cancer.
The FDA determined that PROVENGE meets the criteria for Fast Track designation in that PROVENGE shows the potential to improve survival in the intended patient population of men with asymptomatic, metastatic, androgen-independent prostate cancer. The potential of PROVENGE to provide a survival benefit was based on results from the primary Phase 3 efficacy study, D9901, and supporting data from D9902A, which were recently discussed with the FDA in a pre-BLA meeting.

These specific trials demonstrated improved life expectancy for late-stage victims who had largely exhausted their treatment options, e.g., the malignant cells were no longer controlled by hormones and had penetrated to other regions of the patients’ bodies. Fast Track Status is vital to rapid introduction of a new product to clinical practice because sections of the biologic licensing application (BLA) will be reviewed by FDA as soon as ready, and therefore FDA inquires and requests for more data can be made without waiting for a formal complete application. The most recent announcement:

SEATTLE, WA, June 29, 2006 – Dendreon Corporation (Nasdaq: DNDN) today announced the publication of the results of its pivotal Phase 3 study (D9901) of PROVENGE® (sipuleucel-T) in the July issue of the Journal of Clinical Oncology. The article highlights the significant survival benefit and favorable safety profile of PROVENGE, the Company's investigational active cellular immunotherapy, in men with advanced androgen-independent prostate cancer. The Company plans to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) later this year to obtain approval to market PROVENGE.

Thus Dendreon now expects to submit the formal, complete application by the end of 2006, the hope being that approval for at least certain groups of patients might be forthcoming in 2007.

The procedure calls for three treatments as the total program of therapy. Side effects should be mild since a natural process is being stimulated in contrast to chemotherapy which typically introduces about three toxic compounds in a “cocktail” designed to disrupt processes like cell division throughout the body with the result that numerous vital functions are stopped throughout the body with a syndrome of detrimental effects, e.g., stopping red cell formation and inducing anemia, disrupting the gastrointestinal tract causing nausea, and weight loss.

The cost of the procedure is still undetermined and may be very high. Consider the cost to Medicare and third-party insurers when one million American men are thought to have prostate cancer - or even to more modestly address only numbers such as over 200,000 new cases that are diagnosed annually or 30,000 men who die of this form of cancer every year. If the cost is $25,000, total cost for treating 100,000 men is $2.5 billon, and much higher costs being rumored. Production costs, R&D, clinical-trial and marketing expenses are all costs that Dendreon must recover to stay financially sound, be rewarded for its risks, and be able to fund development of other immunologically valuable products now in its “pipeline.”

On the flip side of the coin, what are the current costs for prostate-cancer treatments? A few days ago, I spent $400 for a one-month supply of estrogen patches (Vivelle.dot 16/week) and the companion medication Avodart at $2.50/capsule four times/day=$10/day, another $300/month. This is by no means to total monthly cost for this therapy which can run six to eight months. The cost of a quality surgical prostatectomy, the state-of-the-art procedure being nerve-sparing, robotic-assisted, minimally invasive surgery using the DaVinci Surgical System produced by Intuitive Surgical, Inc. is a very substantial amount, as is any major surgical procedure.

This brief overview gives you a small window on the when, how, and costs of cancer vaccine development. No matter which therapeutic approach is chosen, the cost for the number of patients needing treatment is in the billions of dollars/year.

For more on Dendreon’s vaccine, see www.dendreon.com.

Evans Roth