Supplementary Material for: Genomic and Immune Features in an Intrahepatic Cholangiocarcinoma Patient with Microsatellite Instability-High Suffered Rapid Acquired Resistance to PD-1 Inhibitor

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.

引言：肝内胆管癌（Intrahepatic cholangiocarcinoma, ICC）是一类高度侵袭性的肝脏恶性肿瘤，预后极差。近年来，免疫检查点抑制剂（immune checkpoint inhibitors, ICIs）——如程序性细胞死亡蛋白1（programmed cell death 1, PD-1）抑制剂——在包括ICC在内的多种肿瘤类型中展现出颇具前景的治疗潜力。微卫星高度不稳定（microsatellite instability-high, MSI-H）是实体瘤中指导ICIs治疗的重要生物标志物，MSI-H患者的客观应答率显著高于微卫星稳定/微卫星低度不稳定（microsatellite stability/microsatellite instability-low, MSS/MSI-L）患者。且约80%~90%的MSI-H患者在获得初始应答后，可维持持久的临床获益。然而，部分患者在初始治疗阶段即出现原发性耐药，另有部分患者在长期治疗后会产生获得性耐药。病例报告：本文报告1例MSI-H型ICC患者，该患者在以卡瑞利珠单抗（Camrelizumab，一种PD-1抑制剂）作为二线治疗方案获得短期缓解后，出现快速疾病进展。研究通过下一代测序（next-generation sequencing, NGS）与多重免疫荧光染色（multiplex immunofluorescence staining, mIF）分析了该患者的基因组及免疫特征，以探索此MSI-H病例中ICIs快速获得性耐药的潜在机制。讨论与结论：基因组与免疫组化分析结果显示，转化生长因子β受体2（TGFBR2）突变、HLA B44超型缺失、携带B62超型，以及肿瘤微环境中PD-L1阳性细胞、巨噬细胞与调节性T细胞（Tregs）增多，可能与该MSI-H患者ICIs治疗获益无法持续存在关联。