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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.
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.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
415 enrolled.
Median follow-up 17.5 months
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Overall survival (final analysis)primary | Trastuzumab emtansine 2.4 mg/kg weekly | 228 | 7.9 months | 1.15 (0.87 to 1.51) | 0.86 (one-sided) | link |
| Taxane (docetaxel or paclitaxel) | 117 | 8.6 months | ||||
| Grade 3 or worse adverse events | Trastuzumab emtansine 2.4 mg/kg weekly | 224 | 60% | - | - | link |
| Taxane (docetaxel or paclitaxel) | 111 | 70% |
Shares Trastuzumab emtansine, Roche / Genentech, Paclitaxel / nab-paclitaxel, Antibody-drug conjugate (ADC) and the tag subtype-trials.
Shares HER2-positive gastric cancer, Paclitaxel / nab-paclitaxel, Gastric & gastro-oesophageal junction cancer, Antibody-drug conjugate (ADC) and the tag subtype-trials.
Shares HER2-positive gastric cancer, Gastric & gastro-oesophageal junction cancer, Antibody-drug conjugate (ADC) and the tag subtype-trials.
Shares HER2-positive gastric cancer, Gastric & gastro-oesophageal junction cancer and the tag subtype-trials.
Shares Docetaxel, Paclitaxel / nab-paclitaxel and the tag subtype-trials.
Shares Roche / Genentech, Docetaxel and the tag subtype-trials.
Shares Docetaxel, Gastric & gastro-oesophageal junction cancer and the tag subtype-trials.
Shares Roche / Genentech and the tag subtype-trials.