Federal health regulators say the toxic side effects of an experimental cancer drug from Onyx Pharmaceuticals may outweigh the drug's benefits for patients with a type of blood cancer.

The Food and Drug Administration warned that patients taking the drug carfilzomib in company studies had a high rate of heart and lung side effects, some which were fatal. The FDA posted its review
of the drug ahead of a Wednesday meeting of its cancer drugs panel.

Onyx has asked the FDA to approve carfilzomib as a treatment for patients with advanced forms of multiple myeloma whose disease has
spread despite treatment with other drugs.

Onyx shares fell almost 5 percent in premarket trading.

Multiple myeloma affects plasma cells in bone marrow. Over 50,000 people have the disease in the U.S., and about 20,000 new
cases are diagnosed every year.