Treatment-Emergent Resistance to Asciminib in Chronic Myeloid Leukemia Patients Due to Myristoyl-Binding Pocket-Mutant of BCR::ABL1/A337V Can Be Effectively Overcome with Dasatinib Treatment.

Despite the groundbreaking success of tyrosine kinase inhibitor therapy, the management of chronic myeloid leukemia patients is often impaired by resistance due to specific point mutations in the BCR::ABL1 oncogene. Upon classical ATP-competitive inhibitor treatment, these single nucleotide variants occur in the tyrosine kinase domain of ABL1. The novel allosteric BCR::ABL1 inhibitor asciminib was developed to treat CML patients alone or in combination to overcome or potentially prevent these treatment-emergent TKD mutations. Here, we present a case of a patient undergoing first-line asciminib therapy, and subsequently develop a specific BCR::ABL1/A337V point mutation, which resulted in asciminib resistance. Switching to second-line dasatinib treatment successfully overcame asciminib resistance and helped to achieve a deep molecular response. In case of treatment failures caused by single asciminib-specific point mutations, dasatinib therapy is a feasible choice.