Therion to close, sell assets after cancer drug trial fails

Therion Biologics Corp. , a 15-year-old Cambridge company trying to develop a new breed of vaccines to fight cancer, will be shuttered and sold after its most promising drug candidate failed a pivotal human test, the company's chief executive said yesterday.

In a test on 255 patients with advanced pancreatic cancer, Therion had hoped its vaccine would extend the patients' average life expectancy from three to five months. The company said the drug failed to reach that goal, although it did not release further details.

Upon hearing the news over the weekend, the company's majority owner, a German billionaire who has supported Therion since 2001, decided to sell off the firm's assets.

``I'm enormously disappointed that we didn't have success, but I'm enormously proud at the same point at what we've been able to do," said chief executive Mark Leuchtenberger , who has run the company since 2002.

Leuchtenberger said he gathered the company's employees in its Kendall Square headquarters yesterday to announce that half of the 100-person workforce would be laid off as the company prepared itself for sale and abandoned its plans to bring a drug to market.

The failure of the trial also marks another high-profile setback for the concept of cancer vaccines, highly specialized treatments that doctors hope can train the immune system to hunt down and kill cancer cells.

Unlike a typical shot to prevent measles or flu, so-called ``therapeutic vaccines" are designed not to prevent cancer, but rather teach the immune system to recognize cancer cells and attack them before they can spread. Such vaccines have raised the hopes of patients and researchers, but have proved persistently difficult to turn into real drugs. (Therapeutic vaccines are unrelated to Gardasil, the recently approved vaccine that prevents a virus that can trigger cervical cancer.)

The California company CancerVax Corp. went out of business earlier this year after a key trial of a melanoma vaccine failed last fall. Other firms with promising early-stage results have struggled to show similarly positive effects in larger human trials.

``You're seeking an enormous change in medicine, but those things are hard to come by, and you accept the risks that these products will fail," Leuchtenberger said.

Therion is widely considered a leader in the field of therapeutic vaccines. Founded in 1991 to develop vaccines against AIDS, the company began to target cancer in the late 1990s. It received a boost when a German software billionaire named Hans-Werner Hector read about Therion's approach in a newspaper article and began investing tens of millions of dollars, becoming the majority owner.

Therion's leading candidate for a vaccine, Panvac , looked good in early tests on cancer patients. If the recent trial had succeeded, the company was expecting to file an application for federal approval by the end of the year.

Earlier this month the company also announced disappointing results for a second vaccine, Prostvac , which failed to reach its goal of improving progression-free survival in advanced prostate-cancer patients. But Prostvac showed a potential benefit for one subgroup of patients, and a larger test is scheduled to begin later this year or early next year.

Despite the setback in the two trials, both of Therion's vaccines are still in several human trials against other cancers, many funded by the National Cancer Institute.

In anticipation of succeeding with at least one of its vaccines, Therion had recently built a manufacturing facility in East Cambridge. The plant, with a suite of pressure-controlled clean rooms and carefully filtered air, had the capacity to make more than 100,000 doses of the vaccine a year, enough to supply the commercial market.

Leuchtenberger said he had already taken calls from potential buyers of the company's assets, which include the two drugs, the vaccine facility, and 70 issued patents.

Stephen Heuser can be reached at sheuser@globe.com.