[Mechanisms of resistance to the allosteric BCR::ABL1 inhibitor asciminib].

Asciminib is a first-in-class allosteric inhibitor that specifically targets the myristoyl pocket of BCR::ABL1 and has shown efficacy in patients with chronic myeloid leukemia (CML) who are resistant or intolerant to prior tyrosine kinase inhibitors (TKIs). Despite its unique mechanism of action, several resistance mechanisms to asciminib have been identified. BCR::ABL1 kinase domain mutations, including A337V, C464W, and compound mutations involving T315I, can interfere with asciminib binding or allosteric regulation. Additionally, BCR::ABL1 transcript variants lacking the SH3 domain, such as e13a3 and e14a3, exhibit primary resistance by disrupting the autoinhibited conformation required for asciminib activity. Non-BCR::ABL1 mechanisms that also contribute to resistance include overexpression of efflux transporters such as ABCG2 and P-glycoprotein, which reduce intracellular drug accumulation. Moreover, novel insertion mutations like p.I293_K294insSLLRD have been shown to impair the allosteric inhibition of ABL1. Combination therapies with ponatinib or other agents, as well as newer TKIs like olverembatinib, have demonstrated potential in overcoming resistance in preclinical and clinical models. Understanding these diverse resistance mechanisms is critical for optimizing asciminib-based treatment strategies and guiding the development of effective combination therapies for patients with resistant CML.