BACKGROUND: Gallbladder carcinoma (GBC) is an extremely aggressive tumor of the biliary tract with a bleak prognosis, and the evidence supporting the benefit of available systemic therapy for advanced GBC is scarce. Herein, this study intended to investigate the real-world outcome of chemotherapy combined with programmed death-1 (PD-1) inhibitor for the management of unresectable or recurrent GBC. METHODS: From January 2018 to December 2023, consecutive patients who were treated with systematic treatment, including chemotherapy or the combination of chemotherapy plus PD-1 inhibitor, for unresectable or recurrent GBC were retrospectively identified. Clinical data regarding baseline characteristics, therapeutic response, adverse events (AEs), and oncological outcomes were collected. RESULTS: The eligible patients were allocated to combination therapy arm (n = 46) and mono-chemotherapy arm (n = 19). After propensity score matching (PSM), 16 patients were allocated in each arm. The overall survival (OS) and progression-free survival (PFS) of combination therapy were marginally superior to mono-chemotherapy both before and after PSM. The combination therapy exhibited advantage over mono-chemotherapy in regards to partial response (PR) (before PSM: P = 0.009
after PSM: P = 0.037) and objective response rate (ORR) (before PSM: P = 0.006
after PSM: P = 0.015). In combined therapy cohort, 1 patient achieve a complete response, and 13 patients were assessed as appropriate for surgical excision, among which 1 patient refused further surgical intervention. CONCLUSIONS: In patients with unresectable or recurrent GBC, the combination of chemotherapy and PD-1 inhibitor as first-line therapy exhibited prolonged OS and PFS, and increased PR and ORR over those receiving chemotherapy alone, with an acceptable toxicity profile. The combination therapy may be a potential conversion therapy in unresectable GBC patients.