(Reuters) - Nearly 20 percent of patients with an aggressive form of leukemia experienced complete remission along with prolonged survival from treatment with an experimental Celgene Corp drug, according to data from an early-stage study released on Wednesday.
The drug, enasidenib, delivered high overall response rates in patients with acute myeloid leukemia (AML) whose disease had relapsed following prior treatments.
Available data from 176 patients showed 40.3 percent responded to the treatment, with 19.3 percent achieving complete remission.
Median overall survival for relapsed AML patients was 9.3 months and rose to 19.7 months among those who experienced complete remission.
Patients in the trial had run out of treatment options and would have been expected to live only about three or four months, said Dr. Eytan Stein from Memorial Sloan Kettering Cancer Center in New York, who led the study.
Stein called the early results extremely promising.
"For patients who have a limited life expectancy, this is a fantastic new treatment that in many people will hopefully extend their lives," Stein said.
Unlike chemotherapy that kills cancer cells, the Celgene drug works by transforming leukemia cells in the bone marrow into normal mature white blood cells.
The data was included in a brief summary of the Phase I study that will be presented next month at the American Society of Clinical Oncology meeting in Chicago.
In addition to the complete remissions, enasidenib led to complete remission with incomplete return to normal blood cell count in 6.4 percent of patients and partial remission in 6.3 percent of patients.
In a dose escalation portion of the study, maximum tolerated dose was not reached at doses up to 650 milligrams daily. The 100 mg daily dose was chosen for the study going forward.
Researchers reported that the drug was well tolerated with no serious adverse side effects of concern.
AML, a fast-growing cancer of the blood and bone marrow, is one of the most common adult leukemias diagnosed in about 15,000 Americans each year.
Stein said he was looking forward to further enasidenib studies "so we can get this therapy to our patients as soon as possible."
Reporting by Bill Berkrot; Editing by Bill Rigby