Association of immune‐related expression profile with sensitivity to chemotherapy in esophageal squamous cell carcinoma

Neoadjuvant chemotherapy (NAC) followed by surgery is one of the standard therapeutic approaches in Japan for patients with locally advanced esophageal carcinoma. Recently, the JCOG1109 study revealed that NAC with docetaxel, cisplatin and 5‐fluorouracil (5‐FU) (DCF‐NAC) is superior to NAC with cisplatin and 5‐FU, and has now become the standard preoperative chemotherapy. Using a microarray system, we have previously investigated the expression profiles of endoscopic biopsy samples from patients with esophageal squamous cell carcinoma (ESCC) before DCF‐NAC (preNAC) and identified 17 molecules as biomarkers predictive of a pathologically complete response to DCF‐NAC. Here, we re‐grouped our previous dataset based on the histopathological response grade with the addition of several microarray profiles and conducted a re‐analysis using bioinformatic web tools including DAVID, GSEA, UALCAN, and CIBERSORTx. We identified 204 genes that were differentially expressed between the highly resistant and sensitive groups. Some of these differentially expressed genes (DEGs) were related to the immune response and showed higher expression in the sensitive group. UALCAN showed that high expression of 28 of the top 50 DEGs was associated with a favorable prognosis (p < 0.25), and that this reached a significant (p < 0.05) level for 18 of them, suggesting that patients with high expression of these genes might have benefited from chemotherapy and thus had a better outcome. In preNAC biopsy tissues from a DCF‐sensitive case, we demonstrated the presence of cells expressing mRNA for CXCL9, one of the prognosis‐related DEGs. Our results highlight the association of immune‐related expression profile in preNAC ESCC with the DCF‐NAC efficacy.