Efficacy and Safety of Bosutinib in Chronic Phase CML Patients Developing Pleural Effusion Under Dasatinib Therapy

Introduction Dasatinib (DAS) is a second-generation (2G) tyrosine-kinase inhibitor (TKI) approved for the first- and second-line treatment of chronic myeloid leukemia (CML) patients. Though highly effective, DAS displays a distinct safety profile, with pleural effusion (PE) occurring in a significant proportion of patients. Among factors associated with DAS-related PE, concomitant pulmonary and cardiovascular diseases have emerged as the most common. Bosutinib (BOS) is another 2G-TKI that has proved to be effective in CML patients failing previous TKIs, with limited cardiac and pleural toxicity. Aims To analyse safety and efficacy of BOS therapy in chronic phase (CP) CML patients developing PE under DAS. Methods We retrospectively collected 20 CP-CML patients referring to several Italian hematology centers who have been receiving BOS in second- or subsequent line, after development of one or more PE with DAS. Cytogenetic and molecular responses were evaluated according to the ELN recommendations, with major molecular response (MMR) defined as BCR-ABLIS ratio