Case report: a case of R0 resection in a patient with PD-L1-negative, microsatellite-stabilized advanced pancreatic cancer after down-stage treatment with a PD-1 inhibitor in combination with chemotherapy.

Background: Pancreatic ductal adenocarcinoma (PDAC) is a gastrointestinal tumor with high morbidity and mortality. Despite advances in diagnostic and therapeutic modalities, the outcome and prognosis of PDAC remain poor. Most patients have locally advanced disease (30%-35%) or distant metastases (50%-55%) at the time of diagnosis. The treatment of unresectable pancreatic ductal adenocarcinoma (UR-PDAC) remains an urgent problem. In this study, we report that a patient with UR-PDAC underwent significant tumor shrinkage after PD-1 inhibitor combination chemotherapy, and obtained R0 (pathologically negative margin) resection and long-term survival.

Case Presentation: A 51-year-old woman was diagnosed with pancreatic cancer (stage III). She underwent 3 cycles of preoperative neoadjuvant therapy (NAT) with programmed cell death protein 1 (PD-1) antibody in combination with chemotherapy and the tumor shrank from 4.0 × 3.3 cm to 0.9 cm without significant adverse effects. The patient underwent conversion surgery (CS) and achieved R0 resection, and no tumor cells remained as confirmed by pathology.

Conclusion: PD-1 antibody combination chemotherapy regimens have significant efficacy and do not add additional side effects in UR-PDAC patients, heralding advances in UR-PDAC treatment. We may have a way to give UR-PDAC patients access to curative treatment and long-term survival. This case of UR-PDAC patient with PD-L1-negative and microsatellite stability (MSS) gives us a more comprehensive understanding of the treatment options of immune-combination chemotherapy.