Unexpected Favorable Outcome To Sintinib Monotherapy in A Relapse PDAC Patient With High TMB

Background Immune checkpoint inhibitors have not been widely used for pancreatic cancer treatment probably because of low immunogenic or stromal fibrotic tumor, among which only pembrolizumab was recommended for DNA mismatch repair deficiency (dMMR) by NCCN. Case presentation Here we report a 56-year-old man suffered from pancreatic ductal cancer (PDAC) with liver metastasis after radical surgery. NGS revealed remarkably high burden of TMB (49.92Muts/Mb) and microsatellite stability (MSS). Sintilimab monotherapy was continuously administrated after failure of combined chemotherapy, leading to stable disease within 22 months and few immunotherapy related AEs happened. Conclusions To our best knowledge, this is the first to report a good outcome achieving 22 months progression-free survival after PDAC metastasis with monotherapy of an immune checkpoint inhibitor. TMB may serve as a potential immunotherapy-related predictor in PDAC patients and help physicians make optimum clinical strategy.