[A Case of Suspected Pure Red Cell Aplasia Due to Nivolumab Treatment for Unresectable Esophageal Cancer].

Immune checkpoint inhibitor(ICI)combination therapy is the first-line of treatment for unresectable or recurrent esophageal cancer. The frequency and mechanism of immune-related adverse events(irAEs)associated with ICI are still unclear and may require differentiation from other diseases. The present study examined a patient with unresectable, advanced esophageal cancer treated with cisplatin plus 5-fluorouracil(CF)plus nivolumab as the first-line treatment. CF therapy was discontinued after 1 course owing to adverse events. Nivolumab was continued, but progressive anemia stemming from pure red cell aplasia(PRCA), an irAE of nivolumab administration, was observed. Nivolumab was discontinued, but later, interstitial pneumonia also developed, and pulse steroid therapy was begun. After steroid tapering, both the PRCA and interstitial pneumonia improved. At present, about 6 months have elapsed since the last nivolumab administration without any PRCA recurrence or evidence of tumor progression.