Clinical trial results provide the rationale to protect dual HIV-specific T cells with a signaling-defective HIV fusion inhibitor.

Coupling the HIV fusion inhibitor C34 with CXCR4 (C34-CXCR4) protected CD4 T cells from all strains of HIV. Escape from C34-CXCR4 expression proved difficult, requiring more than 21 serial passages, mutations at conserved gp41 sites, and a complete loss of Vpu activity. A dose-escalation phase 1 clinical trial was performed in which up to 10 billion C34-CXCR4-expressing T cells were infused into people with HIV (PWH). While these infusions were safe, we observed limited persistence of these C34-CXCR4 T cells, lack of reconstitution of HIV-specific CD8 T cell responses, and no effect on time to viral rebound after an analytical treatment interruption. We hypothesized that inappropriate expression of a signaling-competent chemokine receptor resulted in the limited persistence of these engineered T cells, so we screened several C34-CXCR4 mutants to identify those that could not respond to CXCL12 and still could mediate potent antiviral activity. A single mutation (D97N) in CXCR4 fulfilled both criteria. T cells co-expressing dual HIV-specific chimeric antigen receptors (CARs) and C34-CXCR4 D97N maintained high C34 expression in vivo and controlled HIV replication better than unprotected dual CAR T cells, suggesting that this C34-CXCR4 D97N construct should be considered for future clinical development.