Clinical Cancer Research
EZH2 Inhibition and Myeloid Risk: A Feature of On-Target Biology
Abstract In March 2026, Ipsen voluntarily withdrew the enhancer of zeste homolog 2 (EZH2) inhibitor tazemetostat (Tazverik) from all markets and indications following results from the confirmatory phase Ib/III SYMPHONY-1 trial demonstrating hematologic second primary malignancies (SPM) in 5.7% of treated patients, compared with none in the control arm. The most frequently reported SPMs were myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Although this finding may be interpreted as an idiosyncratic …