Dendreon set to reveal crucial data on prostate-cancer therapy

After investing $500 million over 10 years, and grappling with delays, layoffs and a stock-market roller coaster, has Dendreon finally struck gold?

The Seattle biotech company is releasing detailed results from a trial of its experimental prostate-cancer treatment called Provenge, a major step in commercializing what would be the first cancer immunotherapy.

Earlier this month, CEO Mitchell Gold announced the Phase 3 trial showed the therapy can help men live longer with terminal forms of prostate cancer. Today, Dendreon is presenting details of the study at a medical conference in Chicago.

Key questions the data should answer include the type and length of the patients' remission, and the extent of the side effects.

The company's Provenge therapy uses a patient's own immune system to fight cancer, with fewer side effects than chemotherapy.

This concept "has been around for decades," Gold said in an interview. "There's been a lot of failure. It's been the Holy Grail in the medical community."

Using blood from a patient, Dendreon mixes white blood cells with a protein commonly found in prostate-cancer cells, aiming to activate the immune system to fight the foreign cells. The blood is then put back in the patient in three injections over a one-month period.

Prostate cancer kills more than 28,000 men annually; more than 186,000 were diagnosed with the disease last year in the U.S.

In an earlier, smaller group study of Provenge, men treated with the vaccine lived an average 4.5 months longer than a control group. About 34 percent of men survived after three years, compared with 11 percent of those in the group that received no actual treatment.

Previous studies showed side effects as fevers and chills for the first one to two days.

Some researchers have voiced skepticism over the treatment, which prolonged survival without actually shrinking tumors.

Gold called Dendreon's current study of 512 men "the first active immunotherapy to ever show an improvement in survival."

In recent years, Dendreon's stock has been both pumped up and pummeled. Two years ago, its shares plunged nearly 65 percent and wiped out almost $1 billion in market value, after the U.S. Food and Drug Administration said more information was needed to approve Provenge.

The FDA wanted details on the chemistry and manufacturing of the product. FDA spokeswoman Karen Riley said some members of the advisory committee had "raised issues about the strength of the data" supporting the therapy's effectiveness.

Earlier this month, when Dendreon announced positive results with the Phase 3 trial, its stock soared, more than doubling in a day.

Gold said findings could transform Dendreon from a research-and-development organization to one focused on commercializing the treatment, expanding its staff in the process.

Dendreon will use the data from this most recent trial to amend its pending license application with the FDA by the fourth quarter of this year, Gold said. The FDA will have six months to review the data and make a decision.

If Provenge is approved, Dendreon will use its own 150,000-square-foot manufacturing facility in New Jersey to support a commercial launch of the product in the United States.

A successful outcome would be good news for the local biotechnology industry, said Chris Rivera, president of the Washington Biotechnology & Biomedical Association.

"It takes several years and hundreds of millions of dollars to get a drug to market," he said. "A vaccine for cancer really is a breakthrough. Ultimately it helps patients' lives. Hopefully it will bring a spotlight back to Seattle biotech."

"It has been a roller-coaster ride," Gold said. "Sometimes the most meaningful and important science is the most controversial."

Kristi Heim: 206-464-2718 or kheim@seattletimes.com