Cystine Restriction Alleviates T Cell Exhaustion and Enhances CAR-T Cell Potency.

Abstract

While chimeric antigen receptor (CAR) T cell therapy has demonstrated significant efficacy in treating hematological 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. Here, we investigated metabolic regulators of CD8⁺ T cell exhaustion, identifying that cystine promotes CD8+ T cell exhaustion. RNA sequencing 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 sequencing 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.