Multinational phase 2 trial of valemetostat for relapsed or refractory peripheral T-cell lymphoma

Valemetostat is a novel dual inhibitor of EZH2 and EZH1. The phase 2 VALENTINE-PTCL01 study, at 47 centers in 12 countries, evaluated clinical activity and safety of valemetostat in patients with relapsed or refractory (R/R) peripheral T-cell lymphoma (PTCL), and its safety in patients with R/R adult T-cell leukemia/lymphoma. Among the R/R PTCL patients, objective response (primary endpoint) was seen in 44% (95% CI 35-53). The most common grade 3 or 4 adverse events were thrombocytopenia (23% of patients in the PTCL group and 50% of patients in the adult T-cell leukemia/lymphoma group), anemia (19% and 46%), and neutropenia (17% and 18%); serious treatment-related adverse events were seen in 40% and 68%. No treatment-related deaths were reported. The authors conclude that treatment with valemetostat leads to durable responses in patients with R/R PTCL, with a manageable safety profile.