Dual-targeting LILRB3/LILRB4 CAR-T cells for the treatment of monocytic acute myeloid leukemia.

Monocytic acute myeloid leukemia (AML) is an aggressive malignancy associated with poor prognosis. High expression levels of LILRB3 and LILRB4 are commonly observed in monocytic AML. In this study, the expression of LILRB3 and LILRB4 was analyzed in monocytic AML patient samples, leukemic stem cell-enriched populations, and AML cell lines, revealing frequent co-expression and suggesting that a dual-targeting approach may provide enhanced therapeutic benefit. Accordingly, dual-targeting chimeric antigen receptor (CAR)-T cells were engineered using a single-chain variable fragment (scFv) derived from a humanized antibody capable of recognizing both LILRB3 and LILRB4. In vitro, LILRB3/4 CAR-T cells exhibited potent, antigen-dependent cytotoxicity against AML cell lines and primary AML blasts with minimal toxicity to normal hematopoietic stem/progenitor cells. Additionally, these CAR-T cells induced superior lysis of double-positive leukemic cells compared with single-positive populations. In both subcutaneous and systemic AML xenograft models, treatment with LILRB3/4 CAR-T cells significantly reduced tumor burden and prolonged survival. Collectively, these results demonstrate that LILRB3/4 CAR-T cells represent a promising therapeutic strategy for monocytic AML.