A new leukemia drug from Novartis is being hailed by doctors as a breakthrough, but it could prove among the most expensive therapies ever on the market. For a single treatment, the price is expected to reach hundreds of thousands of dollars. "From what we're hearing, this will be a quantum leap more expensive than other cancer drugs," said Leonard Saltz, chief of gastrointestinal oncology at Memorial Sloan Kettering Cancer Center in New York. Novartis has not announced a price for the medicine, but British health authorities have said a price of $649,000 for a one-time treatment would be justified, given the significant benefits. The cancer therapy was unanimously approved by an FDA advisory committee in July, and its approval seems all but certain. The treatment, CTL019, belongs to a new class of medications called CAR T-cell therapies, and has been tested in patients whose leukemia has relapsed in spite of chemotherapy or a bone-marrow transplant. In a clinical trial, 83% of those treated with CAR T-cell therapy have gone into remission. FDA is scheduled to decide on approval by October 3. The agency is also considering a CAR T-cell therapy from Kite Pharma. A third company, Juno Therapeutics, halted the development of one of its CAR T-cell therapies after five patients died from complications of treatment.