Bristol-Myers awaits OK of cancer drug

In 1996, James Allison, a California researcher, uncovered a way in mice to unleash the body's disease-fighting immune system against cancer. While he was certain the approach could lead to a new kind of treatment against human tumors, he was unable at first to persuade drug companies to pursue the idea.

"I hit a wall for a couple of years," Allison, now at Memorial Sloan-Kettering Cancer Center in New York, said in an interview. "They thought the immune system could never take care of a big mass of tumors."

Now, a skin-cancer drug based on the concept is close to getting U.S. clearance for its developer, Bristol-Myers Squibb Co. If the Food and Drug Administration approves the drug, called ipilimumab, by its scheduled deadline Saturday, it would become the first marketed medicine proven to extend survival in metastatic melanoma, skin cancer that has spread and is generally lethal.

The drug would also be the first in a new class of immune-boosting medicines able to treat an array of tumors. Instead of directly destroying tumor cells or disrupting their ability to grow, like most cancer drugs, these treatments remove molecular brakes that prevent immune system cells from attacking cancer.

Ipilimumab sales in melanoma could reach $925 million by 2017, said Seamus Fernandez, an analyst at Leerink Swann & Co. in Boston

"It's not a stretch to say this would be a multibillion-dollar class" if the drug works in common forms of the disease such as prostate and lung cancer, he said. "Bristol is way ahead of everyone on the immunotherapy front."