Cystine Restriction Alleviates T-cell Exhaustion and Enhances CAR T-cell Potency

Abstract Although chimeric antigen receptor (CAR) T-cell therapy has demonstrated significant efficacy in treating hematologic malignancies, its application in solid tumors remains challenging. A major limitation of CAR T-cell efficacy in solid tumors is the functional exhaustion of CD8+ T cells. In this study, we investigated metabolic regulators of CD8+ T-cell exhaustion, identifying that cystine promotes CD8+ T-cell exhaustion. RNA sequencing (RNA-seq) analysis of an in vitro exhaustion model revealed that SLC7A11 was significantly upregulated in exhausted CD8+ T cells. A monoclonal antibody specifically targeting SLC7A11 was subsequently generated, and its binding affinity was rigorously validated. Single-cell RNA-seq and functional studies demonstrated that inhibition of SLC7A11 promoted the expansion of CD8+ stem-like memory T cells and alleviated T-cell exhaustion. In vivo, treatment with the anti-SLC7A11 antibody enhanced the antitumor efficacy of CAR T cells. Mechanistically, SLC7A11 inhibition suppressed cystine uptake, which activated the GCN2–eIF2α–SLC1A5 signaling axis. Upregulation of SLC1A5 increased glutamine uptake to stimulate oxidative phosphorylation and support mitochondrial fitness. Together, these findings demonstrate that cystine restriction alleviates CD8+ T-cell exhaustion and enhances the efficacy of CAR T-cell therapy. Significance: Inhibition of SLC7A11-mediated cystine uptake improves the anti-tumor activity of CD8+ CAR-T cells by activating the GCN2-eIF2α-SLC1A5 axis to promote oxidative phosphorylation and mitochondrial fitness, overcoming T cell exhaustion.