NEW YORK (Reuters) - Interest in Dendreon Corp's Provenge vaccine to treat prostate cancer seems to be waning following recent approval of Johnson & Johnson's more-convenient and faster-acting Zytiga treatment, according to some doctors and industry analysts.
"The bloom is off the rose for Provenge because patients are looking for something that can treat them more quickly," and with greater convenience, said Charles Duncan, a biotechnology analyst for JMP Securities.
Although Provenge extended patient lives by an average of about four months in clinical trials, it does not significantly delay progression of symptoms -- including the bone pain which is a hallmark of advanced prostate cancer.
Even so, hopes for Provenge were sky high when U.S. regulators approved it in April 2010 for patients with prostate cancer who had failed to benefit from standard medicines that work by blocking the body's production of testosterone. Some analysts had expected the vaccine, which spurs the immune system to attack prostate cancer cells, to eventually capture annual sales of more than $4 billion.
But Duncan, whose company helped sponsor the "Cancer Immunology: A Long-Awaited Reality" conference in New York on Thursday, said Provenge is likely to generate peak annual sales of no more than $500 million because of shortcomings that have become evident to patients and doctors.
They include the time and inconvenience of extracting white blood cells from patients and sending them off to Dendreon plants, where they are combined with vaccine components. Patients then receive the final product through infusions.
Dr. Susan Slovin, an oncologist with Memorial Sloan-Kettering Cancer Center, said many patients and doctors are gravitating instead toward J&J's Zytiga -- a pill approved in recent months for advanced prostate cancer patients that have failed to benefit from chemotherapy.
The drug, known by its chemical name abiraterone, also prolonged life by about four months in clinical trials. But patients experience symptom relief far sooner with it than with Provenge, said Slovin, who was interviewed at the conference sponsored by strategy consulting firm MD Becker Partners LLC.
J&J'S PILL COMING ON STRONG
"Abiraterone is taking the market by storm; there is a much faster effect with it" than Provenge, Slovin said. "Patients feel they're getting something beneficial. Pain is markedly improved, along with the ability to eat, drink, go out and do what they normally would do."
"The patient says, 'Look, I really don't see the need to sit here and send my (blood) to wherever. I really don't want to wait. I want to take a pill and go to Florida.' "
Moreover, while Zytiga is expensive -- at about $5,000 a month, usually for eight cycles -- it is far less costly than Provenge.
Dendreon stunned investors in August by withdrawing its own sales forecast for Provenge because it was taking longer than expected for doctors to become comfortable with reimbursement issues for the product, which costs $93,000 for a course of treatment.
"I don't think Provenge will fall out of the arena; I do think it will still be used, but not with the same alacrity as when it first hit our formulary," said Slovin, whose hospital is one of the world's most prestigious cancer centers.
Dr. James Gulley, a director of clinical trials for the National Cancer Institute, said there is a "clear utility" for Provenge.
"Patients love the idea that your immune system is helping you fight cancer," he said. But Gulley said its manufacturing process poses challenges that have no doubt hampered demand for the product. "The vaccine has to be made for each individual patient."
Gulley is leading clinical trials of an experimental vaccine to treat prostate cancer that could be taken out of the freezer and injected into patients -- eliminating the hassles seen with Provenge.
The National Cancer Institute developed the vaccine, called ProstVac, and licensed it to Danish biotechnology company Bavarian Nordic. NCI would be entitled to royalties on sales of the vaccine, which is slated to move into late-stage trials in coming weeks.
Gulley said ProstVac prolonged patient lives by eight months in mid-stage trials -- roughly twice the benefit seen in separate trials of Provenge and Zytiga. But he cautioned that ProstVac's true potential will not be known until its far-larger planned Phase III trials are completed.
He said the vaccine, which coaxes immune system T-cells to attack a protein called Prostate-Specific Antigen (PSA) -- could prove to be a bigger drug than Provenge.
"Here's why: because it is off the shelf. There are no logistical constraints."
Currently, the world's top selling prostate cancer drugs are Taxotere (docetaxel), a chemotherapy sold by Sanofi, and drugs that reduce testosterone, the male hormone that fuels the growth of prostate cancer. They include AstraZeneca Plc's Zoladex and Casodex, and widely-used Lupron.
Prostate cancer kills about 250,000 men a year globally and is the second most common cause of cancer death in men in the United States, after lung cancer.
(Reporting by Ransdell Pierson, editing by Bernard Orr)
Copyright 2011 Thomson Reuters.
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