Targeting CARM1 impairs DNA damage repair and attenuates B-cell acute lymphoblastic leukemia progression.

B-cell acute lymphoblastic leukemia (B-ALL) is a prevalent hematological malignancy, posing difficulties in identifying efficacious treatment strategies for refractory and recurrent patients. Our research revealed that coactivator-associated arginine methyltransferase 1 (CARM1) was highly expressed in B-ALL and associated with unfavorable prognostic outcomes. Down-regulation and inhibition of CARM1 effectively suppressed proliferation and colony formation of B-ALL, while also inducing apoptosis and cell cycle arrest. Mechanistically, inhibition or down-regulation of CARM1 reduced PARP1 level and contributed to double-strand breaks (DSBs) accumulation. Inhibition of CARM1 and PARP1 synergistically supressed B-ALL development. Significantly, the inhibition of CARM1 was found to promote memory differentiation and reduce the exhaustion of CD19-CAR-T cells. Taken together, CARM1 inhibition not only suppressed B-ALL but also enhanced the durability of CAR-T cells against B-ALL, which provides novel insights into the tumor suppression and immune regulation of CARM1 inhibition on cancer therapy.