Bosutinib is an oral BCR::ABL1-targeting tyrosine kinase inhibitor (TKI) approved in several countries, including Japan, as first-line therapy for adult patients with newly diagnosed chronic-phase chronic myeloid leukemia (CP-CML) at a starting dose of 400 mg once daily (QD) [1–3]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.