Asciminib: the first-in-class allosteric inhibitor of BCR::ABL1 kinase

The prognosis of patients with chronic phase (CP) chronic myeloid leukemia (CML) has significantly improved due to the development of potent BCR::ABL1 tyrosine kinase inhibitors (TKIs). However, approximately 15‒20% of patients ultimately experience treatment failure due to resistance or intolerance to TKI therapy. As the prognosis of patients in whom multiple TKIs fail remains poor, an optimal therapeutic approach is required to treat the condition. Asciminib, an allosteric inhibitor that targets ABL1 myristoyl pocket, has been approved by the Food and Drug Administration for use in patients with CP-CML resistant or intolerant to ≥2 prior TKIs or those with T315I mutation. In a phase 1 trial, asciminib monotherapy showed a relatively favorable safety profile and potent efficacy in patients with and without the T315I mutation. In a subsequent phase 3 trial, asciminib treatment was associated with a significantly higher major molecular response rate and lower discontinuation rate than bosutinib in patients with CP-CML for whom two previous TKIs failed. Several clinical trials are being performed in various clinical settings to evaluate the role of asciminib as a frontline treatment for newly diagnosed CP-CML, either as a single agent or in combination with other TKIs as a second-line or additive treatment to improve treatment-free or deep remission. This review summarizes the incidence, available therapies, and outcomes of patients with CP-CML who experienced treatment failure, the mechanism of action, preclinical and clinical data, and ongoing trials for asciminib.