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Biliary tract cancers (BTCs) comprise a heterogeneous group of aggressive malignancies with unfavorable prognoses. The benefit of chemotherapy seems to have reached a bottleneck and, therefore, new effective therapeutic strategies for advanced BTCs are needed. Molecularly targeted therapies in selected patients are rapidly changing the situation. However, the low frequency of specific driver alterations in BTCs limits their wide application. Recently, immunotherapeutic approaches are also under active investigation in BTCs, but the role of immunotherapy in BTCs remains controversial.PubMed, Web of Science, and meeting resources were searched for relevant articles published from January 2017 to May 2022. The search aimed to identify current and emerging immunotherapeutic approaches for BTCs. Information on clinical trials was obtained from https://clinicaltrials.gov/ and http://www.chictr.org.cn/.Immunotherapy in BTC patients is currently under investigation, and most of the investigations focused on the application of immune checkpoint inhibitors (ICIs). However, only a subgroup of BTCs with microsatellite-instability high (MSI-H)/DNA mismatch repair-deficient (dMMR) or tumor mutational burden-high (TMB-H) benefit from monotherapy of ICIs, and limited activity was observed in the second or subsequent settings. Nevertheless, promising results come from studies of ICIs in combination with other therapeutic approaches, including chemotherapy, in advanced BTCs, with a moderate toxicity profile. Recent studies demonstrated that compared to GEMCIS alone, durvalumab plus GEMCIS significantly improved patient survival (TOPAZ-1 trial) and that ICIs-combined chemoimmunotherapy is poised to become a new frontline therapy option, regardless of TMB and MMR/MSI status. Adoptive cell therapy and peptide- or dendritic-based cancer vaccines are other immunotherapeutic options that are being studied in BTCs. Numerous biomarkers have been investigated to define their predictive role in response to ICIs, but no predictive biomarker has been validated, except MSI-H/dMMR.The role of immunotherapy in BTCs is currently under investigation and the results of ongoing studies are eagerly anticipated. Several studies have demonstrated the safety and efficacy of ICIs in combination with chemotherapy in treatment-naive patients, such as the phase III TOPAZ-1 trial, which will change the standard care of first-line chemotherapy for advanced BTCs. However, further research is needed to understand the best combination with immunotherapy and to discover more predictive biomarkers to guide clinical practice.

Background: Intrahepatic cholangiocarcinoma (ICC) is characterized by a dismal prognosis with limited therapeutic options. To explore phosphatase and tension homology deleted on chromosome ten (PTEN) as a biomarker for proteasome inhibition in ICC, we conducted a phase II trial to assess the second line efficacy of bortezomib in PTEN-deficient advanced ICC patients. Methods: Between July 1, 2017, and June 30, 2021, a total of 130 patients with advanced ICC were screened by PTEN immunohistochemical staining and 16 patients were enrolled. Patients with PTEN deficiency who had progressed after gemcitabine combined cisplatin received single-agent bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 of a 21-day cycle. The primary endpoint was objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors v1.1. Results: The median time of follow up was 4.63 months (95% CI: 0.7~17.2 months). Among the 16 enrolled patients, 13 of them had completed treatment with bortezomib at least 2 cycles and been evaluated. The ORR was 23% (3/13) and disease control rate was 54% (7/13). The median progress-free survival (mPFS) was 2.95 months (95% CI: 2.1~5.1 months) and the median overall survival (mOS) was 7.2 (95% CI: 0.7~21.6 months) months in the intent-to-treat patients. Treatment-related adverse events of any grade were reported in 16 patients, with thrombopenia being the most common toxicity. Patients with PTEN staining score of 0 were more likely to benefit from bortezomib than those with staining score > 0. Conclusions: Bortezomib yielded encouraging objective response and a favorable overall survival as a second-line therapy in PTEN-deficient ICC patients. Our findings suggest bortezomib as a promising treatment option in selected ICC patients with PTEN deficiency. Trial Registration: ClinicalTrials.gov (NCT03345303).