Synergistic Effect of Fecal Microbiota Transplantation, γδT Cell Immunotherapy, and Pembrolizumab in Refractory Advanced Pancreatic Cancer: A Case Report.

Pancreatic cancer (PC) remains one of the most lethal malignancies with limited treatment options, particularly in advanced stages. Emerging immunotherapeutic strategies, such as Gamma Delta (γδ) T cell therapy paired with microbiota management, have demonstrated promise. We report a case of a 75-year-old male diagnosed with advanced-stage and poorly differentiated PC who demonstrated significant clinical improvement following a novel therapeutic approach combining fecal microbiota transplantation (FMT), γδ T cell therapy, and pembrolizumab. Initial chemotherapy and radiotherapy were discontinued due to adverse effects. Pre-treatment the CA19-9 (1206 U/mL), tumor markers were significantly elevated with CEA, CA15-3 and CA125 all within normal limits. No pathogenic mutations (e.g., BRCA1/2, PALB2) were identified. A comprehensive assessment revealed tumor progression, immunosuppression, and gut microbiota dysbiosis, resulting in FMT and γδ T cell therapy being introduced alongside pembrolizumab. The combination therapy resulted in the clearance of circulating tumor cells (CTCs), normalization of CA19-9 to 72 U/mL, improved clinical symptoms, and a marked reduction in tumor size, as confirmed by CT. Tolerability was excellent with no serious adverse events occurred. This case suggests that FMT combined with γδ T cell therapy may be a promising immunotherapeutic strategy for advanced PC. Further studies are needed to validate these findings.