Dendreon’s Provenge vaccine now awaits the F. D. A.’s decision following the advisory panel hearing in Washington D. C. March 29.

Provenge is intended as the first treatment of its kind to stimulate a patient’s own immune system against prostate cancer. If it’s approved, analysts say it could generate up to $1 billion in annual sales.

Provenge is made for each individual patient. Scientists take the patient’s own white blood cells, mix them with a genetically engineered protein and reintroduce them into the patient. Specifically, blood is drawn from the patient and dendritic cells are extracted from the blood and loaded in the laboratory with a recombinant fusion protein consisting of prostatic acid phosphatase (PAP) linked to granulocyte-macrophage colony-stimulating factor (GMCSF). This product is infused into the source patient at repeatable intervals; during trials, patients received uo to 3 infusions of vaccine.

In two studies, as we reported March 28 in covering F. D. A.’s questions to its advisory panel, the company failed to demonstrate the product could slow the
progression of prostate cancer, the No. 2 killer of men in the United States. However, in a three-year analysis of 127 men with late-stage cancer, the median survival time for patients receiving Provenge was 4.5 months longer than patients taking a placebo.

After three years, 34 percent of the men taking Provenge were still alive, compared with 11 percent on the placebo.

The committee advising the F. D. A. is made up of experts in cell and gene therapy. They agreed unanimously that Provenge was safe. In a 13-4 vote they concluded the drug was “substantially effective.”

Reporting for The Seattle Times in Dendreon’s home town, where some two hundred jobs depend on this vaccine, Kirstin Orisini-Mienhardt writes: “Public testimony by cancer patients was a pivotal point in Thursday’s daylong meeting and helped the panel better understand the unmet need for therapy for late-stage prostate cancer, said Dr. Celestia Higano, associate professor of medicine and urology at the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle. Higano was the local investigator on one Provenge trial and was at the panel meeting.

Prostate-cancer advocates, patients and their families gave emotional testimony on their struggles with the disease, which kills about 27,000 men a year in the United States, according to the American Cancer Society.”

But as she also reported, “Jonathan Aschoff, senior biotechnology analyst with Brean Murray Carret, in New York, told the press that he doesn’t think the FDA will ultimately approve Provenge and has been advocating a “sell” since 2004.”

“‘I haven’t spoken to a single institutional investor that said they were going to buy this stock [Friday],’ said Aschoff.”

But Dendreon’s stock rose by more than 40% soon after the F. D. A. panel hearing.

David Miller, president of Seattle-based Biotech Stock Research, told the press that he’s optimistic Provenge will be approved.

Steve Fleischmann, a Seattle prostate-cancer patient and advocate, spoke at the hearing at Dendreon’s invitation. Fleishmann, 51, recently learned his cancer had returned after being in remission for 3-½ years. He will soon start radiation treatments.

“‘If this drug doesn’t get approved, then what? What do I face?’ said Fleishmann, who has not participated in any of the clinical trials.”

FDA may approve or reject the drugs and also may grant an “approvable” status and require the company to finish a third, ongoing clinical study. That study is enrolling 500 patients and won’t produce results until 2010.

References:
The Seattle Times, March 30
Immunotherapy of hormone-refractory prostate cancer with antigen-loaded dendritic cells. J. Clin )ncol., 2000.

Dendritic cells: In the forefront of immunopathogenesis and vaccine development – A review. Journal of Immune Vased Therapies and Vaccines, 2004.

What is a dendtric cell? Wayne State University, n.d.

More about Provenge on PSA Rising: Press Releases and Medical News, 2004 – 2007

Dendreon’s Phase 3 Trial Shows Provenge Vaccine Extends Survival in Patients with Advanced Prostate Cancer Oct 28, 2004

Dendreon Reports Preliminary D9902A Trial Data For Provenge in Patients With Advanced Prostate Cancer Jan. 11, 2005

Dendreon Announces FDA Grants Fast Track Status for Provenge Nov 7, 2005

Provenge prostate cancer vaccine linked to longer survival for asymptomatic hormone refractory stage. June 28, 2006

Dendreon Announces New Data Analyses Presented at Prostate Cancer Foundation Scientific Retreat Oct 20, 2006

Dendreon Announces New Data Analysis Presented at Chemotherapy Foundation Symposium Nov 10, 2006