A combinatorial CAAR-T cell strategy to eliminate factor VIII inhibitors in preclinical models of hemophilia A.

Chimeric autoantibody receptor T (CAAR-T) cell therapy extends CAR-T technology to target autoreactive immune cells, offering a novel approach for treating autoimmune disorders. In hemophilia A, the development of anti-factor VIII (FVIII) inhibitors poses a major clinical challenge. This study investigates the therapeutic potential of CAAR-T cells engineered with FVIII C1 or A2 domains to eliminate inhibitor-producing B cells. In vitro cytotoxicity assays confirmed that C1 and A2 CAAR-T cells exhibited comparable killing efficiency against their respective targets. In an F8KO hemophilia A mouse model, both CAAR-T cells significantly reduced circulating FVIII inhibitors, while their combination further suppressed inhibitor re-emergence after FVIII rechallenge. In a humanized NCG mouse model, combined CAAR-T therapy effectively inhibited in vivo target cell expansion. These findings demonstrate that CAAR-T therapy, particularly the combinatorial approach, holds promise for addressing FVIII inhibitor formation in hemophilia A, offering a targeted and effective treatment strategy.