Pancreatitis in a patient with recurrent endometrial cancer caused by long-term pembrolizumab monotherapy

Abstract

Synopsis: A 67-year-old woman diagnosed with endometrial cancer (pT3aN0M0) was treated with surgery and adjuvant chemotherapy (paclitaxel plus carboplatin). Four years and two months later, computed tomography (CT) scans revealed bone and lung metastases, leading to a new course of chemotherapy (paclitaxel plus carboplatin). Bone recurrence was identified 5 years and 1 month after surgery. A genetic examination revealed a tumor status with high microsatellite instability. A complete response was achieved with pembrolizumab treatment. Twenty-five months later, a blood test revealed elevated levels of cancer antigen 19-9 (CA19-9) and glycated hemoglobin, while CT demonstrated an enlarged pancreas. Despite having imaging and pathologic results that were indicative of autoimmune pancreatitis, gastroenterologists ultimately diagnosed her with pancreatitis induced by pembrolizumab. After she discontinued pembrolizumab, serum CA19-9 levels normalized and subsequent CT scans displayed a reduction in pancreas size. No recurrence of pancreatitis and adverse event was observed 3 years and 4 months after pembrolizumab treatment. This case suggests that pancreatitis, which resembles autoimmune pancreatitis was induced by pembrolizumab treatment, necessitating collaborative management by all departments. Attention should be paid to immune-related adverse events following long-term treatment with pembrolizumab.