- Trastuzumab emtansine (T-DM1)+capecitabine (vs T-DM1 alone) had high toxicity and no added benefit in patients with previously treated HER2+ metastatic breast cancer (mBCa) in the phase 2 TRAXHER trial.
- The phase 1 component defined the maximum tolerated dose (MTD) of capecitabine at 700 mg/m2 for HER2+ mBCa and HER2+ locally advanced/metastatic gastric cancer (LA/mGC).
Why this matters
- Combined T-DM1 and capecitabine does not warrant further testing for patients with previously treated HER2+ mBCa.
- International phase 2 trial of 81 patients randomly allocated to combination therapy (with capecitabine at the MTD) vs 80 patients assigned to T-DM1 alone (3.6 mg/kg).
- Funding: F. Hoffmann-La Roche, Ltd.
- The capecitabine MTD was 700 mg/m2 (n=11 with mBCa and n=6 with LA/mGC) in the phase 1 component.
- In the phase 2 component, no difference was found in objective response rate (44.4% of the combination group vs 36.3% of the T-DM1 group; P=.34) in patients with previously treated HER2+ mBCa.
- Median OS was not estimable (NE) for the combination group (NE; 90% CI, NE-NE) and 24.7 months for the T-DM1 group (stratified HR, 0.87; 90% CI, 0.51-1.48).
- Adverse events of all grades were observed in 95% of the combination group (44% with grades 3-4) and 88% of the T-DM1 group (41% with grades 3-4).