INTRODUCTION
Ph+, CML
MYELOPROLIFERATIVE NEOPLASM, PHILADELPHIA CHROMOSOME, CHRONIC MYELOID LEUKEMIA, CML, RECIPROCAL TRANSLOCATION
Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm defined by the presence of the Philadelphia chromosome (Ph), which is a result of reciprocal translocation of the Abelson (TKIs currently available in Japan include the first‐generation TKI imatinib, the second‐generation TKIs nilotinib, dasatinib, and bosutinib, and the third‐generation TKI ponatinib.Asciminib, a novel, first‐in‐class BCR‐ABL1 inhibitor that acts by STAMP (specifically targeting the ABL myristoyl pocket), has a mechanism of action distinct from approved ATP‐competitive TKIs.In phase 1, first‐in‐human, dose‐escalation study in heavily pre‐treated patients with CML‐CP, asciminib (10–200 mg once daily [qd] or twice daily [bid]) showed clinically meaningful efficacy, including a major molecular response rate (MMR; Asciminib was further investigated in the ASCEMBL study (NCT03106779), an ongoing, international, open‐label, randomized, active‐controlled, phase 3 study in patients with CML‐CP (not harboring the Recently, asciminib has been approved by the US Food and Drug Administration (FDA; October 2020) for treatment of patients with Ph‐positive (Ph+) CML‐CP, previously treated with ≥2 TKIs and for adults with Ph + CML‐CP harboring the T315I mutationJapan is one of the several countries participating in the ASCEMBL study. In this report, we present the week 24 results of a subgroup analysis of Japanese patients enrolled in the ASCEMBL study, which aimed to determine if results in this subpopulation are comparable to those from the global study population. As only a small number of Japanese patients were enrolled in the bosutinib arm, this report focuses mainly on the efficacy and safety of asciminib in this patient subgroup.