CD39 and PD-L1 co-expression may serve as potential indicators for evaluating the efficacy of neoadjuvant immunotherapy in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) contributes a major therapeutic challenge in gastrointestinal oncology due to its aggressive behavior. Neoadjuvant immunotherapy combined with chemotherapy (NIT) has emerged as a novel treatment strategy for ESCC. However, clinical responses to NIT vary substantially among individuals, and relying solely on PD-L1 expression to predict therapeutic benefit remains insufficient. Therefore, identifying novel biomarkers to evaluate patient responses to NIT is urgently needed. CD39, an ectonucleotidase with ATPase and ADPase activity, plays a critical role in tumor immune evasion. Using integrated immunohistochemical and multiplex immunofluorescence analyses, we systematically evaluated the expression of CD39 and key tumor immune microenvironment markers in ESCC tissues from patients undergoing NIT. Our results showed that the expression levels of CD39, PD-L1, and α-SMA were significantly higher in the NIT group compared to the surgery-alone group. Moreover, CD39, PD-L1, PD-1, CD8, and α-SMA were markedly elevated in patients with effective responses to NIT compared to non-responders. Therapeutic response analysis revealed that patients with high co-expression of CD39 and PD-L1 derived greater benefit from NIT. Further subcellular localization analysis indicated that CD39 was expressed in membrane and cytoplasm of tumor cells, stromal cells and T cells. Interestingly, patients exhibiting co-high expression of stromal cell-derived CD39 rather than tumor cell-derived CD39 rather than tumor cell-derived CD39 with PD-L1 demonstrated optimal therapeutic outcomes. These findings suggest that CD39 and PD-L1 play critical roles in modulating the response to NIT and may serve as candidate biomarkers for guiding individualized treatment strategies in ESCC in the future.