Over a third of high-risk leukemia patients respond to experimental new drug

A new drug for patients with acute myeloid leukemia (AML) marked by a specific type of genetic mutation has shown surprising promise in a Phase II clinical trial.

In more than a third of participants, the leukemia was completely cleared from the bone marrow, and as a result, many of these patients were able to undergo potentially curative bone marrow transplants, according to investigators at the Johns Hopkins Kimmel Cancer Center and nine other academic medical centres around the world.

Many of the participants who did well with the new drug, quizartinib or AC220, had failed to respond to prior therapies.

"We can put two-thirds to three-quarters of adults with AML into remission with chemotherapy, but there's a 50 per cent chance of the disease coming back, which usually ends up being fatal," says Mark Levis, MD, PhD., lead investigator on the study and associate professor of oncology and medicine at Johns Hopkins.

Levis adds, "Many patients in this trial were able to go on to receive a potentially life-saving bone marrow transplant. It caught us by surprise how well it works."

For the clinical trial, researchers enrolled 137 AML patients, the majority of whom carried a mutation called FLT3-ITD in a gene within their leukemia cells. The FLT3 gene produces an enzyme that signals bone marrow stem cells to divide and replenish. In about a quarter of patients with AML, the disease mutates FLT3 so that the enzyme stays on permanently, causing rapid growth of leukemia cells and making the condition harder to treat.