A new study of leukemia drug Mylotarg, pulled from the U.S. market last year due to safety concerns, found it to be effective when used at low doses in older adults but questions about toxicity remain. Pfizer Inc voluntarily halted U.S. sales of Mylotarg, also known as gemtuzumab, after a study showed that adding it to chemotherapy did not extend survival for patients with previously untreated acute myeloid leukemia (AML), an aggressive bone marrow cancer. That trial also showed more deaths in the first couple of months of treatment. The fatality rate was 5.7 percent for Mylotarg patients, compared with 1.4 percent without the drug. But several academic groups have continued clinical studies of the drug, with some of those results presented in San Diego this week at a meeting of the American Society of Hematology.
