Integrative Analysis of Cytotoxic Lymphocytes‐Mediated Tumour Killing Related Genes Reveals <scp>LDHA</scp> as a Novel Glioblastoma Therapeutic Target

Glioblastoma (GBM) features profound immunosuppression and metabolic reprogramming that undermine immunotherapy. We sought biomarkers that capture cytotoxic lymphocyte activity and nominate tractable targets. Using TCGA, we quantified NK/CD8+ T-cell infiltration (CIBERSORTx), identified differentially expressed genes and derived a three-gene prognostic index (CTLsTKPI: LDHA, TNIP1, PTPN2) via Cox and LASSO. Performance was assessed in REMBRANDT, CGGA325 and CGGA693, and CTLsTKPI was incorporated into a multivariable nomogram alongside clinical variables. We examined associations with immune checkpoints, tumour mutational burden and stemness, and performed functional studies of LDHA in GBM cells, CAR-NK92 assays and an orthotopic mouse model. We detected 3195 DEGs versus normal brain; 119 tracked with cytotoxic infiltration. CTLsTKPI stratified survival in TCGA (AUCs 0.694/0.656/0.819 at 1/2/3 years) and validated across cohorts; the nomogram outperformed individual predictors (AUC 0.78). High CTLsTKPI aligned with checkpoint pathway activation, Treg/macrophage enrichment and reduced activated NK/CD8⁺ T cells. LDHA was the dominant adverse component, linked to glycolysis; its overexpression enhanced proliferation, migration and invasion, while lactate impaired CAR-NK cytotoxicity. In vivo, LDHA inhibition (GNE-140) synergised with PD-1 blockade to reduce tumour burden and prolong survival. CTLsTKPI provides a clinically actionable biomarker, and LDHA represents a rational therapeutic target.