Introduction: Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive liver malignancy with poor prognosis. Recently, the development of immune checkpoint inhibitors (ICIs), such as programmed cell death 1 (PD-1) inhibitors, has emerged as a promising strategy in multiple tumor types, including ICC. Microsatellite instability-high (MSI-H) is an important biomarker for ICIs in solid tumors. The response rate in patients with MSI-H is significantly higher than in those with microsatellite stability/ microsatellite instability-low (MSS/MSI-L). And approximately 80% to 90% of the patients with MSI-H could maintain sustained clinical benefits once they had an initial response. However, some patients could have primary resistance at the beginning, and some might have acquired resistance after long-term treatment. Case Presentation: We present the case of an ICC patient with MSI-H who suffered rapid progression after a short-term remission with Camrelizumab, a kind of PD-1 inhibitor, as second-line treatment. The patient’s genomic and immune features were analyzed by next-generation sequencing and multiplex immunofluorescence staining (mIF) to explore the possible mechanisms of the rapidly acquired resistance of ICIs in this MSI-H case. Discussion/Conclusion: The genomic and immunohistochemical analysis showed that TGFBR2 mutation, loss of HLA B44 supertype, carrying B62 supertype, and increased PD-L1+ cells, macrophages and Tregs in the tumor microenvironment might be related to the non-sustain benefit of ICIs in this MSI-H patient.

The Author(s). Published by S. Karger AG, Basel