Serum Autoantibodies Against Glycolytic and Mitochondrial Proteins in Esophageal Carcinoma: Diagnostic and Exploratory Prognostic Significance

Background: Metabolic reprogramming toward aerobic glycolysis, commonly referred to as the Warburg effect, is a hallmark of cancer. Such metabolic alterations may lead to aberrant expression and release of glycolytic and mitochondrial proteins, which can act as tumor-associated antigens and elicit humoral immune responses. However, whether patients with esophageal carcinoma (EC) develop a broad autoantibody response against these metabolic proteins, and whether such an autoantibody profile has diagnostic or prognostic relevance, has not been systematically investigated. Objective: To determine (1) whether serum autoantibodies against 18 proteins involved in glucose metabolism and mitochondrial pathways are broadly elevated in patients with EC and have diagnostic potential; (2) whether combining selected autoantibodies improves diagnostic discrimination; and (3) whether individual or combined autoantibody profiles show exploratory associations with postoperative overall survival. Methods: Serum autoantibody levels against 18 metabolic proteins (SLC2A1, ASPSCR1, GK2, ALDOA, TPI1, GAPDH, PGK1, PGK2, ENO1, PGAM1, PKM, PDHB, PCK1, LDHA, SDHB, FH, IDH, and ATP5B) were measured in 191 patients with EC and 96 healthy donors using AlphaLISA. For diagnostic combination analysis, a multivariable logistic regression model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab was evaluated in the complete-case cohort. In 91 surgically treated patients, exploratory overall survival analyses were performed using Kaplan–Meier curves and log-rank tests after dichotomization of antibody levels. Results: All 18 autoantibodies were significantly elevated in patients with EC compared with healthy donors (all P < 0.05), with individual AUC values ranging from 0.593 for SDHB-Ab to 0.735 for ENO1-Ab. The three-autoantibody model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab achieved an AUC of 0.812 (95% CI, 0.751–0.873), with a sensitivity of 68.1% and a specificity of 83.9%, and showed significantly greater diagnostic discrimination than the individual autoantibodies evaluated in the same cohort. In exploratory postoperative overall survival analyses, PCK1-Ab and SDHB-Ab showed significant differences in overall survival by log-rank testing. Several combined autoantibody profiles were also associated with survival differences, including high ENO1-Ab/low PGAM1-Ab, high SDHB-Ab/low FH-Ab, high ALDOA-Ab/high TPI1-Ab, and high PCK1-Ab/high SDHB-Ab versus low PCK1-Ab/low SDHB-Ab. Conclusions: The consistent elevation of autoantibodies against all 18 evaluated metabolic proteins suggests the presence of a broad humoral immune response to metabolic antigens in patients with EC. A three-autoantibody model combining ENO1-Ab, PDHB-Ab, and ALDOA-Ab improved diagnostic discrimination compared with individual markers. Exploratory analyses also identified individual and combined autoantibody profiles associated with postoperative overall survival, warranting further validation in independent cohorts.