标准剂量免疫检查点抑制剂 (SD-ICIs) 是微卫星不稳定高 (MSI-H) 晚期/转移性结直肠腺癌 (mCRC) 初始治疗的标准治疗，但临床前数据表明低剂量 ICI (LD-ICI) 也可能具有类似的疗效。对 2017 年 6 月至 2023 年 1 月期间接受 ICI 的 MSI-H mCRC 患者进行了回顾性研究。该研究的主要终点是 12 个月无进展生存期 (PFS)，使用 Kaplan-Meier 方法计算。研究期间共有 65 名患者可供分析。 60 名患者 (92%) 接受纳武单抗治疗，其余患者接受帕博利珠单抗治疗。 18 名患者 (28%) 接受了一线 ICI，而 47 名患者 (72%) 在后期一线接受了 ICI。 30 名患者 (47%) 接受 LD-ICIs（全部接受纳武单抗），其余患者接受 SD-ICIs (53%)。在中位随访 16.5（95% CI，11.8 至 21.2）个月时，整个队列未达到中位 PFS。 LD-ICI 队列中的 12 个月 PFS 率为 90%，而 SD-ICI 队列中为 75.8%。接受 ICI 作为一线治疗的患者（12 个月 PFS-94.4%）或后期治疗期间（12 个月 PFS-77.9%；P = 0.56）没有统计学差异。当前研究中的 ICI 显示生存率这与 MSI-H mCRC 患者的开创性试验相似。低剂量 ICI 似乎对 MSI-H mCRC 有效，应在临床试验中进行前瞻性探索。 MSI-H 状态的患者应在可行的情况下接触 ICI，无论是治疗初期还是治疗后期。

Standard-dose immune checkpoint inhibitors (SD-ICIs) are the standard of care as initial therapy in microsatellite instable-high (MSI-H) advanced/metastatic colorectal adenocarcinomas (mCRC), but there are preclinical data to suggest that low-dose ICIs (LD-ICI) might also have similar efficacy.A retrospective study of patients with MSI-H mCRC receiving ICIs between June 2017 and January 2023 was conducted. The primary end point of the study was 12-month progression-free survival (PFS), which was computed using the Kaplan-Meier method.A total of 65 patients were available for analysis during the study period. Sixty patients (92%) received nivolumab, whereas the remaining received pembrolizumab. First-line ICIs were received by 18 patients (28%), whereas 47 patients (72%) received ICIs during later lines. Thirty patients (47%) received LD-ICIs (all received nivolumab), with the remaining receiving SD-ICIs (53%). At a median follow-up of 16.5 (95% CI, 11.8 to 21.2) months, median PFS was not reached in the entire cohort. The 12-month PFS rate in the LD-ICI cohort was 90%, whereas it was 75.8% in the SD-ICI cohort. There were no statistical differences in patients receiving ICIs as first-line therapy (12 months PFS-94.4%) or during later lines of therapy (12-month PFS-77.9%; P = .56).ICIs in the current study show survivals which are similar to those seen in seminal trials in patients with MSI-H mCRC. Low-dose ICIs appear to work in MSI-H mCRC and should be explored prospectively in clinical trials. Patients with MSI-H status should be exposed to ICIs, whether initially or later during treatment, whenever feasible.