Bristol's Cancer BetRobert Langreth, 07.23.09, 05:26 PM EDT...

Bristol's Cancer Bet
Robert Langreth, 07.23.09, 05:26 PM EDT
Cancer immunotherapy has mostly been a failure so far. With its $2.4B purchase of Medarex, the company wagers it has found a winner.


Attempts to spur the immune system to kill tumors have mostly failed in trials. Now Bristol-Myers Squibb is betting billions that it can make immune-targeting therapies finally work against cancer.

Its $2.4 billion cash acquisition of the biotech firm Medarex ( MEDX - news - people ), announced late Wednesday, represents a giant gamble that immunotherapy will become the next big thing in cancer treatment. Medarex's lead drug, ipilimumab, now in a final-stage trial for advanced melanoma, doesn't target tumors directly at all. Instead it works by removing the brakes on the immune system so it can attack and kill the tumor.

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Yahoo! BuzzIn recent years, evidence has built that the immune system can sometimes attack and kill cancer cells--sometimes--but that cancer finds ways to fight back and evade or blunt the attack. (See "Cancer Miracles") For some people with advanced cancer, ipilimumab may be just enough to trigger a full-fledged anti-tumor attack. Bristol-Myers Squibb ( BMY - news - people ) has been collaborating with Medarex for years but now will get full rights to the drug.

"We wouldn't be betting $2.4 billion in cash unless we were optimistic" it would work, said Bristol-Myers Chief Executive James Cornelius in a conference call. "This will not be a cure-all for all types of cancer" but it could be "complementary to therapies that are out there today." Medarex has other cancer immunotherapies in earlier stages of testing, as well as drugs targeting lupus, rheumatoid arthritis and inflammatory bowel disease.

Bristol's buy is a risky move because numerous treatments and vaccines that aim to stimulate the body against cancer have mostly failed. One of the few that has worked so far is an experimental prostate cancer vaccine from Dendreon ( DNDN - news - people ) that recently had good trial results. The immune system is one of the more complicated parts of the body and doctors are only beginning to understand its intricacies. Another immune-boosting therapy against cancer, the natural immune system protein interleukin-2, has been limited by severe side effects.

Most trials of ipilimumab to date have been in advanced melanoma, where a small percentage of patients have experienced spectacular long-lasting remissions, even as the drug appears to do relatively little for the majority. Why more patients don't respond is a subject of intense research at laboratories worldwide. Some patients get autoimmune side-effects.