There is no clinically available biomarker for efficiently indicating the overall survival or therapy response of gastric cancer (GC). The autoantibodies (Abs) in the sera of anti-far-upstream element-binding protein-interacting repressor-lacking exon2 (FIRΔexon2), anti-sorting nexin 15, and anti-spermatogenesis and oogenesis-specific basic helix-loop-helix 1 were markedly higher in GC patients than in healthy donors (HDs). These Abs were identified by large-scale serological identification of antigens by recombinant cDNA expression cloning screenings and their expression levels were evaluated by amplified luminescence proximity homogeneous assay. In particular, compared with age-matched HDs, the level of anti-FIRΔexon2 Abs in GC patients was significantly higher (P < .001). The Spearman's rank correlation analysis between anti-FIRΔexon2 Abs and clinically available tumor markers such as carcinoembryonic antigen (CEA) was statistically insignificant, indicating that FIRΔexon2 Abs is an independent biomarker. We performed receiver-operating curve analysis to evaluate the anti-FIRΔexon2 Ab as a candidate biomarker with CEA and carbohydrate antigen 19-9 (CA19-9). The overall survival of GC patients with high anti-FIRΔexon2 Abs titer was significantly favorable (P = .04) than that of GC patients who were below detection level of anti-FIRΔexon2 Abs. However, clinical stages were not apparently correlated with the levels of anti-FIRΔexon2 Ab, CEA, and CA19-9. In conclusion, anti-FIRΔexon2 Abs detected in GC patients is a potential biomarker for monitoring a better prognosis. Hence, anti-FIRΔexon2 Abs is a promising biomarker for indicating better overall survival of gastric cancer patients.
Keywords: AlphaLISA; FIRΔexon2 autoantibody; SEREX; gastric cancer; gastrointestinal cancer.
© 2020 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.