Identification of serum microRNAs predicting the response of esophageal squamous-cell carcinoma to nivolumab

Background: Nivolumab, a programmed cell death protein 1 (PD-1) inhibitor, showed promising activity for the treatment of advanced esophageal squamous-cell carcinoma in a phase II study (ONO-4538-07; JapicCTI-No.142422). We explored serum microRNA (miRNA) candidate predictive markers of the response to nivolumab. Methods: In the phase II study, 19 patients received nivolumab (3 mg/kg IV Q2W) at National Cancer Center Hospital. The expression of 2565 serum miRNAs before and during treatment was analyzed using a 3D-Gene Human miRNA Oligo Chip (Toray Industries, Inc.). Immune-related response evaluation criteria used to evaluate response and miRNA expression were compared between responders and non-responders. The top 20 miRNAs by accuracy in receiver operating characteristic curve analysis were identified by leave-one-out cross-validation, and those with the area under curve values > 0.8, cross-validated accuracy > 0.8, and a 0.5 difference in the average log2 expression level between responders and non-responders were further analyzed. Results: Of the 19 patients, five responded to nivolumab. We identified miRNAs related to the response to nivolumab, including one detected in the serum before treatment (miR-1233-5p; AUC = 0.895) and three present after treatment (miR-6885-5p, miR-4698 and miR-128-2-5p; AUC = 0.93, 0.97 and 0.93, respectively). Conclusions: Candidate miRNAs capable of predicting the response to nivolumab were identified in the serum of patients with advanced esophageal squamous-cell carcinoma in ONO-4538-07.