Case Report: Pathologic Complete Response to Induction Therapy in a Patient With Potentially Resectable Pancreatic Cancer.

Immune monotherapy does not appear to work in patients with pancreatic cancer so far. We are conducting a clinical trial that combines programmed cell death protein-1 (PD-1) inhibitor with chemotherapy and concurrent radiotherapy as induction therapy for patients with locally advanced pancreatic cancer (LAPC) and borderline resectable pancreatic cancer (BRPC). Here, we report a case with a pathologic complete response (pCR) and no postoperative complications after the induction therapy. The patient received four cycles of induction therapy and achieved a partial response (PR) with a significant decline of tumor marker carbohydrate antigen 19-9 (CA19-9). Also, peripheral blood samples were collected during the treatment to investigate serial circulating tumor DNA (ctDNA) dynamic changes in predicting the tumor response and outcomes in patients. Our result suggested that PD-1 blockade plus chemotherapy and concurrent radiotherapy is a promising mode as induction therapy for patients with potentially resectable pancreatic cancer. In this case, serial ctDNA alterations accurately provide a comprehensive outlook of the tumor status and monitor the response to the therapy, as validated by standard imaging.