Background <p>Chimeric antigen receptor T (CAR-T) cell therapy holds promise for cancer treatment, but its efficacy is often hindered by metabolic constraints in the tumor microenvironment. This study investigates the role of glutamine in enhancing CAR-T cell function against ovarian cancer.</p> Methods <p>Metabolomic profiling of blood samples from ovarian cancer patients treated with MSLN-CAR-T cells was conducted to identify metabolic changes. In vitro, glutamine pretreatment was applied to CAR-T cells, and their proliferation, CAR expression, tumor lysis, and cytokine production (TNF-α, IFN-γ) were assessed. Mechanistic studies focused on the mTOR-SREBP2 pathway and its effect on HMGCS1 expression, membrane stability and immune synapse formation. In vivo, the antitumor effects and memory phenotype of glutamine-pretreated CAR-T cells were evaluated.</p> Results <p>Elevated glutamine levels were observed in the blood of ovarian cancer patients who responded to MSLN-CAR-T cell treatment. Glutamine pretreatment enhanced CAR-T cell proliferation, CAR expression, tumor lysis, and cytokine production. Mechanistically, glutamine activated the mTOR-SREBP2 pathway, upregulating HMGCS1 and promoting membrane stability and immune synapse formation. In vivo, glutamine-pretreated CAR-T cells exhibited superior tumor infiltration, sustained antitumor activity, and preserved memory subsets.</p> Conclusions <p>Our findings highlight glutamine-driven metabolic rewiring via the mTOR-SREBP2-HMGCS1 axis as a strategy to augment CAR-T cell efficacy in ovarian cancer.</p> Trial registration <p>NCT05372692</p>