Another drug from the emerging menin inhibitor drug class has hit safety issues, after the FDA put an early stage acute myeloid leukemia trial of Kura Oncology Inc.’s KO-539 on partial clinical hold because of a patient death. The news from Kura follows safety issues that emerged from Syndax Pharmaceuticals Inc.’s rival SNDX-5613, where an issue with QT prolongation emerged in at least 5% of patients in otherwise encouraging phase I/II trial results announced in April.