CHICAGO – The investigational drug ivosidenib was associated with durable responses, transfusion independence, and a low rate of serious adverse events in patients with IDH1-mutated relapsed/refractory acute myeloid leukemia (AML), based on results of a phase 1 study presented at the annual meeting of the American Society of Clinical Oncology (ASCO).
Daily oral ivosidenib, which inhibits mutant IDH1 the gene that encodes for isocitrate dehydrogenase 1 and is present in 6%-10% of AML patients, was associated with a complete response rate of nearly 32%. In patients who achieved a complete response, median duration of response was 8.2 months and median overall survival was 18.8 months, Daniel A. Pollyea, MD, University of Colorado School of Medicine, Aurora, reported at the meeting.
A wide variety of study participants achieved transfusion independence, even patients who had lesser and no discernable responses, Dr. Pollyea said. “A significant minority of these patients (with lesser or no response) were able to achieve transfusion independence which is obviously a big achievement with respect to quality of life, and suggestive of the mechanism of action here with respect to differentiation.”
The conclusions ofare “striking,” with response rates and tolerability “very similar” to results seen with the IDH2 inhibitor enasidenib, said Eunice S. Wang, MD, of Roswell Park Comprehensive Cancer Center, Buffalo, N.Y.
Ivosidenib is “likely to become the new standard of care treatment” for IDH1-mutant patients in the relapsed-refractory setting based on the data presented at ASCO, Dr. Wang said in a presentation commenting on the results.
“Given the development of ivosidenib and enasidenib, I think we should all carefully consider whether testing of IDH1 and IDH2 mutational status should also become standard of care in all relapsed and refractory patients, in order to offer them these novel and highly effective as well as well-tolerated targeted therapies,” she said.
Enasidenib was approved by the U.S. Food and Drug Administration (FDA) in 2017 for relapsed or refractory AML with an IDH2 mutation.