Prostate vaccine expected to open new cancer treatment

SEATTLE – (Cancer Digest) – If the FDA approves Dendreon's PROVENGE® therapy for advanced prostate cancer as is expected at it's May 1 meeting, it will mark a the first new class of cancer therapy in decades. In addition to surgery, chemotherapy and radiation, doctors will be able to add vaccines to their anti-cancer arsenal.
Most people are familiar with vaccines that prevent disease, such as polio or measles. Such prophylactic vaccines, as they are called, work by introducing the body's immune system to a potential threat by injecting a disabled particle of the virus or bacteria into the body which triggers and immune response, thus establishing an "army" of immune cells that will recognize and attack that virus should it ever invade.





A therapeutic vaccine, such as PROVENGE, however, takes the opposite approach. A person with prostate cancer or any cancer for that matter, already has immune cells that recognize those abnormal cancer cells and attacks them. Unfortunately, cancer often grows too fast, or mutates in such ways as to outstrip the immune system's ability to effectively battle it. What the PROVENGE system does is extract the immune cells that are most effective in fighting the cancer and then growing them into much larger numbers and boosting their anti-cancer abilities by binding them to an enzyme that revs up their cancer-fighting ability. The cells are then re-infused back into the patient with the hope that with these reinforcements the immune system will at least hold the cancer in check, or reduce it.

In a trial of 500 men with advanced cancer that had spread to other parts of the body published a year ago, men treated with three rounds of PROVENGE survived a median of 4.1 months longer, and increased survival by 38 percent compared to those treated with current therapies.

The most common side effects of the treatment include fevers, chills and flu-like symptoms.

If approved, PROVENGE will be the first FDA-approved therapeutic vaccine, and would open the door for a series of approvals. Of the 13 vaccines in late-stage clinical trials development, Stimuvax (Merck KGaA/Oncothyreon) and MAGE-A3 ASCI (GlaxoSmithKline) both of which are aimed at non-small lung cancer as well as other cancers, may be next to be approved.