# Report gallbladder cancer as its own population in every biliary trial

Source: https://onco.cc/ideas/idea-gbc-report-gallbladder-separately-in-biliary-trials/  
OnCo record `idea-gbc-report-gallbladder-separately-in-biliary-trials` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Every drug gallbladder cancer patients receive was tested in mixed bile duct trials where they were a subgroup. Requiring trials to pre-specify and publish gallbladder results, with a minimum number enrolled, would give the disease its own evidence at almost no cost.

## Summary

ABC-02, BILCAP, ABC-06, TOPAZ-1 and KEYNOTE-966 enrolled gallbladder cancer alongside intrahepatic and extrahepatic cholangiocarcinoma and reported it, if at all, in forest plots. Yet the diseases differ: HER2 positivity runs at 9 to 20 percent in gallbladder and extrahepatic cancers against 5 percent intrahepatic; immune profiles differ by population; and the UK CAPBIL cohort saw no adjuvant benefit in a mostly gallbladder population. A reporting standard (pre-specified gallbladder stratum, minimum enrolment, mandatory subgroup publication) could be asked of sponsors by regulators and journals and would cost the trials almost nothing.

## Fields

- Kind: Idea
- Last checked: 2026-09-24
- Tags: gallbladder-evidence
- Hypothesis: Mandating a pre-specified gallbladder cancer stratum with published results in biliary tract cancer trials will reveal clinically meaningful differences in treatment effect between gallbladder cancer and cholangiocarcinoma within five years.
- Rationale: Prevalence of HER2, immune profile and recurrence pattern already differ between sites; pooled analyses hide effect modification. The cost of a stratum is small; the cost of a wrong extrapolation is borne by every gallbladder patient.
- Proposed test: Retrospective: obtain gallbladder-stratum results from TOPAZ-1, KEYNOTE-966, BILCAP and ABC-06 and test for interaction with site. Prospective: ACTICCA-1 and ARTEMIDE-Biliary01 publish gallbladder strata as primary-paper tables.
- Maturity: speculative
- Actor: regulator

## Sources

- Galdy et al.: HER2 in biliary tract cancers by site (Cancer Metastasis Rev 2017): https://europepmc.org/article/MED/27981460
- Zhu et al.: population-specific immunogenomics of gallbladder cancer (Mod Pathol 2025): https://europepmc.org/article/MED/40541865

## Connected records

- cancers: [Biliary tract cancer (all types)](https://onco.cc/cancers/biliary-tract-cancer/), [Gallbladder cancer](https://onco.cc/cancers/gallbladder/)
- terms: [Hazard ratio (HR)](https://onco.cc/terms/hazard-ratio/)
- trials: [ABC-06](https://onco.cc/trials/abc-06/), [ACTICCA-1](https://onco.cc/trials/acticca-1/), [BILCAP](https://onco.cc/trials/bilcap/), [KEYNOTE-966](https://onco.cc/trials/keynote-966/), [Rilvegostomig + Chemotherapy as Adjuvant Therapy for Biliary Tract Cancer After Resection (ARTEMIDE-Biliary01)](https://onco.cc/trials/nct06109779/), [TOPAZ-1](https://onco.cc/trials/topaz-1/)
- bottlenecks: [Failures are hidden](https://onco.cc/bottlenecks/b-negative-results/), [Rare and paediatric cancers without markets](https://onco.cc/bottlenecks/b-rare-cancers/), [Trial design, endpoints and cost](https://onco.cc/bottlenecks/b-trial-design/)
- key papers: [HER2/HER3 pathway in biliary tract malignancies; systematic review and meta-analysis: a potential therapeutic target?](https://onco.cc/key-papers/paper-galdy-her2-biliary-tract-meta-analysis-cancer-metastasis-rev-2017/), [Population-Specific Immunogenomic Alterations in Gallbladder Cancer and Prognostic Significance](https://onco.cc/key-papers/paper-zhu-population-specific-immunogenomics-gallbladder-cancer-mod-pathol-2025/), [Surgical outcomes in gallbladder cancer: evidence from the UK nationwide CAPBIL study](https://onco.cc/key-papers/paper-mcclements-capbil-surgical-outcomes-gallbladder-cancer-hpb-2026/)
- roadmaps: [Gallbladder cancer roadmap: from a chance finding at gallstone surgery to a disease with its own trials](https://onco.cc/roadmaps/gallbladder-cancer-roadmap/)

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