[Molecularly targeted therapy strategies for adult T-cell leukemia/lymphoma]

Adult T-cell leukemia/lymphoma (ATL) has a very poor prognosis with conventional multidrug chemotherapy. Lenalidomide, an oral anticancer drug classified as an immunomodulator, showed an overall response rate of 46% in a phase II clinical trial in relapsed ATL. The antibody therapy mogamulizumab showed an overall response rate of 50% in a phase II trial of relapsed C-C motif chemokine receptor 4-positive ATL. Brentuximab vedotin has yet to show clear evidence of efficacy due to the limited number of patients enrolled in phase II trials. Epigenetic therapy has also been investigated. The EZH1/2 inhibitor valemetostat showed a response rate of 48% in a phase II trial in relapsed/refractory aggressive ATL. The histone acetylation inhibitor tucidinostat also exhibited efficacy in ATL, with an objective response rate of 30.4%. This review focuses on the abovementioned molecular-targeted agents, which are all currently used in Japan.