Favorable tolerability of asciminib versus ATP-competitive tyrosine kinase inhibitors in the ASC4FIRST study of newly diagnosed patients with chronic-phase chronic myeloid leukemia

Many patients with chronic myeloid leukemia (CML) treated with adenosine triphosphate (ATP)-competitive tyrosine kinase inhibitors (TKIs) experience persistent adverse events (AEs) that negatively impact daily living and the ability to remain on treatment. Asciminib, an allosteric inhibitor of BCR::ABL1, was designed to enhance efficacy and reduce off-target effects vs ATPcompetitive TKIs. The phase 3 randomized ASC4FIRST trial established the overall favorable safety profile of asciminib in patients with newly diagnosed CML in chronic phase (CP). This exploratory post hoc analysis of ASC4FIRST focused specifically on the tolerability of asciminib vs imatinib and asciminib vs second-generation 2G TKIs. Analyses were conducted within each stratum to account for differences between strata; patients prerandomized to the imatinib stratum were older and had higher cardiovascular risk than those in the 2G stratum. Within both strata, patients receiving asciminib experienced fewer difficult-to-tolerate AEs (such as gastrointestinal toxicity, rash, and pleural effusion) and fewer AEs leading to dose modifications and discontinuations due to nonhematologic and hematologic AEs vs the investigator-selected (IS) TKI comparator, with a shorter median duration of dose modification. Additionally, median onset of AEs leading to dose modification occurred later in patients receiving asciminib vs ISTKIs. The safety and tolerability of asciminib observed in the ASC4FIRST trial demonstrate asciminib's excellent benefit-risk profile as a frontline therapy for a broad range of patients with newly diagnosed CML-CP.