Molecular Subtyping of Hepatocellular Carcinoma by T Cell–Mediated Killing Genes: A Multiomic Framework for Prognostic Stratification and Precision Therapeutics

Background: Hepatocellular carcinoma (HCC) is characterized by substantial heterogeneity and poor prognosis despite therapeutic advancements. Genes regulating tumor cell sensitivity to T cell–mediated killing (GSTTKs) have been implicated in immune evasion, yet their potential role in HCC molecular subtyping remains to be fully elucidated. Methods: Multiomics data from TCGA-LIHC were integrated to identify eight prognostic GSTTKs through stringent selection criteria. Consensus clustering and UMAP were employed to define subtypes, with validation performed via nearest template prediction (NTP) algorithm across five independent cohorts. Genomic alterations, immune infiltration, pathway enrichment, and drug sensitivity were systematically analyzed. HBV infection associations were evaluated in four cohorts with complete etiology records. Subtype-specific drug responses were experimentally assessed using representative HCC cell lines. Results: Three GSTTK subtypes were identified with distinct molecular and clinical characteristics, showing consistent prognostic trends across validation cohorts (p < 0.001). GSTTK2, enriched for TP53 mutations and elevated TMB, displayed an immune-excluded phenotype and poorest prognosis. GSTTK3 exhibited relatively favorable outcomes, metabolic pathway enrichment (cytochrome P450 and retinol metabolism), and features suggestive of an immune-permissive microenvironment. GSTTK1 demonstrated intermediate characteristics with LRP1B mutation enrichment. No significant association between HBV status and subtype distribution was observed across analyzed cohorts (p > 0.05), suggesting that the classification may reflect tumor-intrinsic molecular features, though the contribution of viral etiology to early tumor evolution cannot be excluded. Computational analysis predicted potential subtype-specific therapeutic vulnerabilities, and experimental validation indicated that vinorelbine exhibited enhanced cytotoxicity in GSTTK2-representative cells compared to other subtypes (p < 0.01). Conclusion: This study proposes a GSTTK-based molecular classification integrating genomic, metabolic, and immune features, which may offer prognostic value and inform therapeutic stratification. Further prospective validation is warranted to establish clinical utility.