Evolving approaches in advanced gallbladder cancer with complete pathological response using chemo‑immunotherapy: A case report.

The combination of chemotherapy and immunotherapy for metastatic cholangiocarcinoma (CCA) offers promising improvements in survival and response rates beyond traditional treatments. TOPAZ-1 and KEYNOTE-966 have demonstrated the efficacy of combining immunotherapy (durvalumab and pembrolizumab) with chemotherapy, even in gallbladder cancer (GBC), with a complete response rate of 2.7% in the TOPAZ-1 trial. Advanced CCA treated with immunotherapy combinations has shown complete responses influenced by high programmed death-ligand 1 (PD-L1) or Epstein-Barr virus expression. These responses were enhanced by combining radiotherapy with programmed cell death protein 1 (PD-1) blockade. A 62-year-old man was diagnosed with unresectable GBC, distant lymphatic metastases, and local invasion of liver segments 4i and 5, the colonic hepatic flexure, the duodenal bulb, and the pancreatic head. Immunohistochemical examination revealed poorly differentiated squamous cell carcinoma, without expression of PD-L1. Next generation sequencing revealed the mutation of ERBB2 R678Q and a microsatellite stable tumour. The patient started chemo-immunotherapy with cisplatin-gemcitabine plus durvalumab in June 2022. After eight cycles, a significant reduction in tumour volume and markers was reported, and therapy with durvalumab was maintained through November 2023. The subsequent computed tomography scans showed further reduction in the tumour volume, and surgical resection was performed. Histological examinations confirmed the absence of residual tumour or lymph node metastases. As of June 2024, the patient has shown no signs of disease recurrence. Several reports of conversion surgery in GBC exist, but data on pre-surgical chemo-immunotherapy are limited. Furthermore, a complete response without pathological confirmation in CCA and GBC raises several questions regarding the need for surgery after immunotherapy. Although effective disease control and tumour regression have been reported in advanced GBC with combined anti-cytotoxic T-lymphocyte associated protein 4 and anti-PD-1 agents and chemotherapy, further studies are needed to identify reliable predictive biomarkers due to unclear associations with PD-L1 expression or tumour mutational burden. Overall, chemo-immunotherapy has been effective in treating metastatic CCA, especially when tailored to specific molecular profiles. These treatments may lead to complete responses and novel strategies.