Asciminib stands out as the superior tyrosine kinase inhibitor to combine with anti-CD20 monoclonal antibodies for the treatment of CD20 + Philadelphia-positive B-cell precursor acute lymphoblastic leukemia in preclinical models

Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia (Ph+ BCP-ALL) is a high-risk subtype of acute lymphoblastic leukemia characterized by the presence of the BCR::ABL1 fusion gene. Tyrosine kinase inhibitors (TKI) combined with chemotherapy are established as the first-line treatment. Additionally, rituximab, an anti-CD20 monoclonal antibody is administered to adult BCP-ALL patients with ≥20% CD20+ blasts. In this study, we observed a marked prevalence of CD20 expression in patients diagnosed with Ph+ BCP-ALL, indicating a potential widespread clinical application of rituximab in combination with TKI. Consequently, we examined the influence of TKI on the antitumor effectiveness of anti-CD20 monoclonal antibodies by evaluating levels of CD20 on the cell surface and conducting in vitro functional assays. All tested TKI were found to uniformly downregulate CD20 on leukemic cells, diminishing the efficacy of rituximab-mediated complement- dependent cytotoxicity. Interestingly, these TKI displayed varied effects on natural killer (NK) cell-mediated antibody- dependent cytotoxicity and macrophage phagocytic function. While asciminib demonstrated no inhibition of effector cell functions, dasatinib notably suppressed the anti-CD20-monoclonal antibody-mediated NK cell cytotoxicity and macrophage phagocytosis of BCP-ALL cells. Dasatinib and ponatinib also decreased NK cell degranulation in vitro. Importantly, oral administration of dasatinib, but not asciminib, compromised NK cell activity in patients' blood, as determined by an ex vivo degranulation assay. Our results indicate that asciminib might be preferred over other TKI for combination therapy with anti-CD20 monoclonal antibodies.