Safety and efficacy of anti-HER2 agents in the treatment of biliary tract cancers: A systematic review.

639 Background: Limited treatment options exist for patients with locally advanced or metastatic biliary tract cancers (BTCs). Recently, several clinical trials provided preliminary evidence for human epidermal growth factor receptor-2 (HER2) as a new target for patients with HER2 expressing BTC. We conducted a systematic review and pooled analysis of the safety and efficacy of anti-HER2 agents in patients with advanced BTC. Methods: A comprehensive search of PubMed/MEDLINE and EMBASE was performed to identify phase 1, 2, or 3 clinical trials published between January 2019 and March 2024 that evaluated anti-HER2 therapy in locally advanced or metastatic BTC. Primary endpoints included objective response rate (ORR), disease control rate (DCR), and progression-free survival (PFS). Secondary endpoints included the incidence of treatment-related adverse events (TRAEs), rate of treatment discontinuation, and death. Forest plots were generated to summarize the results and demonstrate the effect size estimates for each study, along with their confidence intervals and the pooled estimate from the random-effects model. The random-effects models were configured to use the Restricted Maximum Likelihood method for estimating between-study variance for all analyses. Results: After excluding duplicate and irrelevant articles, data extraction and analysis were performed on eight selected clinical trials. The analysis included 368 patients with a median age of 64 (range 49-68), with 55% being female. Patients were treated with several anti-HER2 agents, including zanidatamab, pertuzumab plus trastuzumab, tucatinib plus trastuzumab, trastuzumab deruxtecan, trastuzumab plus chemotherapy, trastuzumab-pkrb plus chemotherapy and neratinib. The pooled ORR and DCR were 34% (95% CI 24-44) and 64% (95% CI 51-77) respectively. The pooled weighted PFS and median OS survival were 4.8 and 9.4 months, respectively. The pooled duration of response was 5.0 months. In our subset analysis, which included only patients who had received ≥1 prior therapy, the pooled ORR was 30% (95% CI 22-39), the pooled DCR was 62% (95% CI 48-75), and the pooled median PFS was 4.4 months. In the study cohort, 82.6% of patients experienced any adverse event, and 32.1% experienced a grade 3-4 adverse event. Only 5.7% of the patients discontinued treatment secondary to TRAEs. Conclusions: In patients with HER2 expressing BTCs, anti-HER2 therapies demonstrated preliminary signals of efficacy with manageable toxicities, particularly in the second-line setting.