* Provenge meets main goal of Phase III study
* Dendreon to seek U.S. approval in fourth quarter
* Dendreon shares up 138 pct in late afternoon trade (Updates share activity, paragraph 2, last paragraph; adds link to related story, paragraph 9)
By Ransdell Pierson and Lewis Krauskopf
NEW YORK, April 14 (Reuters) - An experimental medicine from Dendreon Corp improved survival in men with advanced forms of prostate cancer, the company said on Tuesday, bolstering chances of it becoming the first approved therapeutic vaccine for any type of cancer.
Shares of Dendreon DNDN.O more than tripled in heavy morning trading to as high as $22.10 and were up 138 percent at $17.38 in afternoon trade as the study results suggested a revolutionary form of therapy is on the horizon for one of the most common cancers.
Unlike traditional vaccines that prevent disease, the company’s Provenge medicine treats it by stimulating the body’s own immune system.
“If you’re in late stages of prostate cancer and your doctor says, ‘You’ll have no side effects with this drug and it will probably extend your life,’ who’s not going to take it?” said Sven Borho, an analyst with OrbiMed Advisors.
The Phase III clinical trial met the main study goal of improving survival, prompting Dendreon to say it will seek U.S. regulatory approval of Provenge in the fourth quarter.
“The successful outcome from the Phase 3 IMPACT study provides validation of the long-pursued goal of harnessing the human immune system against a patient’s own cancer,” Dendreon Chief Executive Mitchell Gold said in a statement.
Prostate cancer is the most common cancer in American men other than skin cancers, according to the American Cancer Society. About one in six men will be diagnosed with prostate cancer during his lifetime.
Paul Latta, an analyst with McAdams Wright Ragen, said Provenge stood to be a $200 million product if it is approved only in the advanced prostate cancer patient group, but could expand to a $1 billion blockbuster if it is expanded to men with earlier stages of the disease.
But Borho, whose New York investment firm owns 2.5 million shares of Dendreon, said Provenge’s annual sales could reach several billion dollars. [ID:nN14290009]
“Dendreon has delivered the goods for sure, this is very exciting,” Borho said.
Aside from OrbiMed, other big institutional shareholders included BAM Capital, Barclays Global Investors, Visium Capital Management and Vanguard Group, according to Reuters data.
The study included 512 men with late-stage prostate cancer who have not benefited from drugs that sharply lower testosterone — the male sex hormone that fuels progression of the cancer.
On a conference call with analysts, Gold said the trial’s results were “unambiguous” and “robust” but the company deferred giving detailed data until a formal presentation on April 28 at the American Urological Association annual meeting in Chicago.
The Seattle-based company said the safety profile of Provenge appeared to be consistent with prior trials.
It would be the first approved cancer immunotherapy, meaning a drug to fight cancer by stimulating the immune system to attack cancer cells.
To make the product, a fragment of the patient’s tumor is sent to a laboratory, which isolates specific proteins linked to the cancer and incorporates them into the vaccine. Once injected, the body’s immune system seeks out and destroys cells containing the target proteins.
An outside advisory panel of doctors recommended in March 2007 that the U.S. Food and Drug Administration approve Provenge, based on favorable efficacy and safety results from an earlier Phase III study.
But the FDA declined to approve the medicine until data from the IMPACT study confirmed earlier trends.
“If (the study) indeed is unambiguous, the FDA might have a little egg on their face for not approving it earlier,” Latta said. “I imagine there’s going to be a ton of pressure on the FDA to get the drug through as soon as possible.”
A number of rival biotechnology companies, including Genitope Corp GTOP.PK and Cell Genesys CEGE.O, have failed in their own long quests to develop successful therapeutic cancer vaccines.
Dendreon confirmed prior statements that it plans to market Provenge on its own in the United States, but it said it remains interested in a marketing partner overseas.
OrbiMed’s Borho predicted Provenge, which is administered only once, would cost more than $50,000.
The leading current treatment for advanced prostate cancer is Taxotere, a Sanofi-Aventis (SASY.PA) chemotherapy that can cause harsh side effects, including neuropathy, hair loss, nausea and vomiting.
Gold in February told Reuters he was supremely confident the IMPACT study would succeed, saying, “We’re on the 10-yard line and close to putting it into the end zone.”
Still, Wall Street was skeptical. Dendreon shares touched a 52-week low of $2.55 in March, and no analysts polled by Reuters Estimates had a “buy” rating on the stock.
“Nobody wanted to stick their head out because over the last 15 years no cancer immunotherapies worked in clinical trials,” said Borho.
Over 61 million shares in Dendreon had traded hands by 3:25 p.m. EDT. (Reporting by Ransdell Pierson and Lewis Krauskopf; Editing by Lisa Von Ahn, Dave Zimmerman)