Some immune-boosting cancer drugs may pose rare heart risks

Doctors have found a disturbing downside to some powerful new drugs that harness the immune system to fight cancer. In rare cases, they may cause potentially fatal heart damage, especially when used together.

The drugs are called checkpoint inhibitors and they have transformed cancer treatment in recent years by helping the immune system see and attack tumors. However, in less than one percent of patients, the immune system seems to attack not only the tumor but also the heart and other muscles.

Doctors stress that this does not negate the huge benefits of these drugs.

A report Wednesday in the New England Journal of Medicine describes two patients who died of heart trouble two weeks after getting two of these drugs to treat the deadly skin cancer melanoma.