MDS patients with mutated IDH2 benefit from enasidenib

There were no treatment-related deaths.

Response and survival

Ten of 17 patients (59%) achieved an overall response, defined as complete response (CR) plus partial response, plus marrow CR, plus hematologic improvement (HI).

One patient achieved CR, 1 had a partial response, 3 had marrow CR, and 5 had HI.

Dr Stein noted that, of the 13 patients who had received prior hypomethylating agent therapy, 7 (54%) had a response with enasidenib.

Of the patients who attained HI, 2 had trilineage and 2 had bilineage improvement.

The median time to response was 21 days (range, 10-87), and the median number of treatment cycles was 3.0.

Patients remained on study for up to 24 months. Four patients in hematologic remission are still on study, and 3 patients proceeded to stem cell or bone marrow transplant, Dr Stein said.

Two patients discontinued because of investigator decision, and 8 discontinued therapy due to death or disease progression.

The limitation of the study regarding overall survival, Dr Stein said, is that the number is very small.

At a median follow-up of 7.5 months, the median overall survival was not reached.

“So I’m not arguing that this is the end word of this,” he said. “This is going to be dynamic as more patients come on these studies. But I think it’s a nice indication that this treatment appears to be well-tolerated and doing good for a large subset of patients.”

Co-occurring mutations

The investigators also analyzed co-occurring mutations in 13 MDS patients.

The small patient population prevented the investigators from making definitive conclusions regarding potential correlations between response and co-mutations.

Nevertheless, Dr Stein said the analysis revealed something “very, very intriguing.”

He noted that 7 patients had ASXL1 mutations, and “those are typically patients who are bad actors.”

“Five of those 7 patients had a response,” Dr Stein said. “And of those 5, 3 of them had received a prior hypomethylating agent. I think it’s at least food for thought that you can salvage a patient who has failed a hypomethylating agent, with poor risk disease. I think this is very, very exciting.”

Celgene Corporation and its collaborator, Agios Pharmaceuticals, sponsored the trial.

*Information in the abstract differs from the presentation.