# GATSBY

Source: https://onco.cc/trials/gatsby/  
OnCo record `gatsby` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

GATSBY tested whether the antibody-drug conjugate trastuzumab emtansine, which works in HER2-positive breast cancer, would also beat chemotherapy in HER2-positive stomach cancer after first treatment; it did not, and the drug was never approved for this cancer.

## Summary

GATSBY was an adaptive phase 2/3 trial in HER2-positive advanced gastric or gastro-oesophageal junction adenocarcinoma that had progressed during or after first-line therapy. Stage 1 randomised patients to two dose schedules of trastuzumab emtansine or to a taxane chosen by the investigator; the 2.4 mg/kg weekly schedule was carried into stage 2 against taxane alone.

Trastuzumab emtansine did not improve overall survival over taxane, the primary endpoint, and the trial was stopped. Together with the earlier failure of lapatinib in this setting, GATSBY showed that HER2 loss and heterogeneity after trastuzumab make second-line HER2 targeting in gastric cancer harder than in breast cancer; the later success of trastuzumab deruxtecan in DESTINY-Gastric01 came from a payload that also kills neighbouring HER2-negative cells.

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-17
- Tags: subtype-trials
- Registry id: NCT01641939
- Phase: 2/3
- Setting: HER2-positive advanced gastric or gastro-oesophageal junction cancer progressing after first-line therapy: trastuzumab emtansine against a taxane (docetaxel or paclitaxel)
- Sponsor: Roche
- Enrolled: 415
- Result: Trastuzumab emtansine did not improve overall survival over taxane chemotherapy in previously treated HER2-positive gastric cancer.

## Sources

- ClinicalTrials.gov NCT01641939: https://clinicaltrials.gov/study/NCT01641939

## Connected records

- cancers: [Gastric & gastro-oesophageal junction cancer](https://onco.cc/cancers/gastric/), [HER2-positive gastric cancer](https://onco.cc/cancers/gastric-her2-positive/)
- drugs: [Docetaxel](https://onco.cc/drugs/docetaxel/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Trastuzumab emtansine](https://onco.cc/drugs/trastuzumab-emtansine/)
- companies: [Roche / Genentech](https://onco.cc/companies/roche-genentech/)
- people: [Peter Thuss-Patience](https://onco.cc/people/peter-thuss-patience/)

---
JSON: https://onco.cc/api/v1/entities/gatsby.json