Advanced intrahepatic cholangiocarcinoma (ICC) has a dismal prognosis. Here, we report the efficacy and safety of combining toripalimab, lenvatinib, and gemcitabine plus oxaliplatin (GEMOX) as first-line therapy for advanced ICC. Thirty patients with pathologically confirmed advanced ICC received intravenous gemcitabine (1 g/m2) on Days 1 and 8 and oxaliplatin (85 mg/m2) Q3W for six cycles along with intravenous toripalimab (240 mg) Q3W and oral lenvatinib (8 mg) once daily for one year. The expression of programmed death-ligand 1 (PD-L1) and genetic status was investigated in paraffin-embedded tissues using immunohistochemistry and whole-exome sequencing (WES) analysis. The primary endpoint was the objective response rate (ORR). Secondary outcomes included safety, overall survival (OS), progression-free survival (PFS), disease control rate (DCR) and duration of response (DoR). As of July 1, 2022, the median follow-up time was 23.5 months, and the ORR was 80%. Twenty-three patients achieved partial response, and one achieved complete response. Patients (21/30) with DNA damage response (DDR)-related gene mutations showed a higher ORR, while patients (14/30) with tumor area positivity ≥1 (PD-L1 staining) showed a trend of high ORR, but without significant difference. The median OS, PFS, and DoR were 22.5, 10.2, and 11.0 months, respectively. The DCR was 93.3%. Further, 56.7% of patients experienced manageable grade ≥3 adverse events (AEs), commonly neutropenia (40.0%) and leukocytopenia (23.3%). In conclusion, toripalimab plus lenvatinib and GEMOX are promising first-line regimens for the treatment of advanced ICC. A phase-III, multicenter, double-blinded, randomized study to validate our findings was approved by the National Medical Products Administration (NMPA, No. 2021LP01825).Trial registration Clinical trials: NCT03951597.

Intrahepatic cholangiocarcinoma (ICC) is highly invasive and carries high mortality due to limited therapeutic strategies. In other solid tumors, immune checkpoint inhibitors (ICIs) target cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD1), and the PD1 ligand PD-L1 has revolutionized treatment and improved outcomes. However, the relationship and clinical significance of CTLA-4 and PD-L1 expression in ICC remains to be addressed. Deciphering CTLA-4 and PD-L1 interactions in ICC enable targeted therapy for this disease. In this study, immunohistochemistry (IHC) was used to detect and quantify CTLA-4, forkhead box protein P3 (FOXP3), and PD-L1 in samples from 290 patients with ICC. The prognostic capabilities of CTLA-4, FOXP3, and PD-L1 expression in ICC were investigated with the Kaplan–Meier method. Independent risk factors related to ICC survival and recurrence were assessed by the Cox proportional hazards models. Here, we identified that CTLA-4+ lymphocyte density was elevated in ICC tumors compared with peritumoral hepatic tissues (P <.001), and patients with a high density of CTLA-4+ tumor-infiltrating lymphocytes (TILsCTLA-4 High) showed a reduced overall survival (OS) rate and increased cumulative recurrence rate compared with patients with TILsCTLA-4 Low (P <.001 and P = .024, respectively). Similarly, patients with high FOXP3+ TILs (TILsFOXP3 High) had poorer prognoses than patients with low FOXP3+ TILs (P = .021, P = .034, respectively), and the density of CTLA-4+ TILs was positively correlated with FOXP3+ TILs (Pearson r = .31, P <.001). Furthermore, patients with high PD-L1 expression in tumors (TumorPD-L1 High) and/or TILsCTLA-4 High presented worse OS and a higher recurrence rate than patients with TILsCTLA-4 LowTumorPD-L1 Low. Moreover, multiple tumors, lymph node metastasis, and high TumorPD-L1/TILsCTLA-4 were independent risk factors of cumulative recurrence and OS for patients after ICC tumor resection. Furthermore, among ICC patients, those with hepatolithiasis had a higher expression of CTLA-4 and worse OS compared with patients with HBV infection or undefined risk factors (P = .018). In conclusion, CTLA-4 is increased in TILs in ICC and has an expression profile distinct from PD1/PD-L1. TumorPD-L1/TILsCTLA-4 is a predictive factor of OS and ICC recurrence, suggesting that combined therapy targeting PD1/PD-L1 and CTLA-4 may be useful in treating patients with ICC.