Prostate cancer vaccine Provenge has long incited passions unlike any other cancer therapy.

Doctors who raised doubts about it received death threats. Health regulators and lawmakers faced loud protests at their offices. A physician at the American Cancer Society was so intimidated by Provenge partisans that he yanked a skeptical discussion of it from his blog.

The vitriol dissipated in April 2010, when the U.S. Food and Drug Administration approved Provenge for advanced prostate cancer, satisfying investors in manufacturer Dendreon and patients who for years had demanded it be put on the market.

But the bell on Round Two sounded when Marie Huber, a trained scientist and former hedge-fund analyst, made it her mission in the last year to analyze what she believes are deadly flaws in the studies that led to the approval of Provenge by the FDA.

She argues that the main reason Provenge seemed to extend survival - a crucial factor in the FDA’s decision - was that older men in the study who did not receive Provenge died months sooner than similar patients in other studies.

She raises the possibility the “placebo” they received was actually harmful and made Provenge, known scientifically as sipuleucel-T, look better by comparison.

As Huber gains traction, most notably with a February paper in the prestigious Journal of the National Cancer Institute, she, too, is receiving threats. One post on an investors’ message board last month suggested that “somebody smack her with a rubber hose.” An email said “don’t think you will be unscathed in this battle you waged on Provenge.”

Provenge is Dendreon’s only product and the company’s stature with investors has waned with disappointing sales. In 2011, product revenues totaled $213.5 million, far from the $400 million Dendreon initially projected.

The company insists Huber’s analysis is flawed and that Provenge has helped thousands of men with prostate cancer.

“I’m looking forward to getting this to patients around the world,” said President and Chief Executive John Johnson.

FIRST CANCER VACCINE

Since it won FDA approval two years ago, Provenge has been Exhibit A for the idea that a patient’s immune system can control or cure cancer. The first therapeutic cancer vaccine to reach the market, Provenge tries to engineer white blood cells, part of the immune system, to vanquish prostate cancer, which killed an estimated 33,720 men in the United States last year.

Its path to approval has all the features of a heavyweight healthcare fight - desperate patients demanding access to a promising therapy, a very expensive drug that extends life only a few months and efficacy data open to interpretation.

The FDA declined to approve the drug in 2007, when a clinical trial failed to show it slowed tumor growth. That incited protests, lawsuits and death threats against physicians on the FDA advisory panel who did not recommend approval, breaking with the 13-4 majority in favor.

“Provenge came along when we didn’t have much to offer for prostate cancer,” said Dr. Len Lichtenfeld of the ACS. “The advocacy community was bursting at the seams for something that worked. When you have that situation, it inflames passions and that can overtake the science.”

In the pivotal trial called IMPACT, published in July 2010, but shared with the FDA months earlier, Provenge extended median survival by 4.1 months to 25.8 months from 21.7 months. That was sufficient for FDA approval. The vaccine costs $93,000 and patients also incur physician and other charges. Medicare agreed to cover Provenge last year, as have private insurers, but doctors initially balked at a long wait for reimbursement.

Huber had long been “utterly intrigued” by Provenge and its “huge promise of harnessing the immune system to battle cancer,” she said in an interview.

In documents JNCI requires authors to sign, she declared no financial conflicts of interest. Neither she nor her former firm nor anyone else she is connected to stands to benefit financially from her analysis, she said.

Instead, she says she is motivated to help “vulnerable and desperate patients” - so much so that she gave up her job, salary and health insurance. Arguing that Provenge is harming these men, she called “the whole thing utterly horrific. The company got away with hiding data and doctors making $7,000 per prescription won’t even engage in discussion” about whether it helps their patients.

After receiving degrees in biochemistry and bioscience enterprise from Cambridge University, Huber began working as an analyst for a hedge fund in 2007. A Thomson Reuters analysis of securities filings confirmed her former firm has not held any positions in Dendreon.

LACK OF EVIDENCE

Each dose of Provenge is custom-made. A nurse or technician withdraws white blood cells from a man’s arm in a three-to-four hour procedure called leukapheresis.

The cells are shipped to a Dendreon manufacturing facility, where for two days they are incubated with a “fusion protein:” One protein that stimulates the cells’ growth and maturation and another called PAP, or prostatic acid phosphatase. PAP is an antigen that studs prostate cancer cells like antennae, pieces of it sticking out of the cells’ surfaces.