GPIbα CAAR T cells function like a Trojan horse to eliminate autoreactive B cells to treat immune thrombocytopenia

Breakthrough treatment for refractory and relapsed immune thrombocytopenia (ITP) patients is urgently needed. Autoantibody- mediated platelet clearance and megakaryocyte dysfunction are important pathogenic mediators of ITP. Glycoprotein (GP) Ibα is a significant autoantigen found in ITP patients and is associated with poor response to standard immunosuppressive treatments. Here, we engineered human T cells to express a chimeric autoantibody receptor (CAAR) with GPIbα constructed into the ligand-binding domain fused to the CD8 transmembrane domain and CD3ζ-4-1BB signaling domains. We performed cytotoxicity assays to assess GPIbα CAAR T-cell selective cytolysis of cells expressing anti-GPIbα B-cell receptors in vitro. Furthermore, we demonstrated the potential of GPIbα CAAR T cells to persist and precisely eliminate GPIbα-specific B cells in vivo. In summary, we present a proof of concept for CAAR T-cell therapy to eradicate autoimmune B cells while sparing healthy B cells with GPIbα CAAR T cells that function like a Trojan horse. GPIbα CAAR T-cell therapy is a promising treatment for refractory and relapsed ITP patients.