- The immunotherapy atezolizumab + trastuzumab emtansine did not increase PFS compared with placebo + trastuzumab emtansine in patients with previously treated HER2+ metastatic breast cancer (mBCa), according to the phase 2 KATE2 trial.
- The study ended prematurely because of futility and more adverse events (AEs) in the atezolizumab group.
Why this matters
- More research is warranted, particularly in the subgroup who had programmed death ligand-1-positive disease because a subgroup analysis could not be performed in this phase 2 study.
- Randomized, double-blind, placebo-controlled phase 2 trial held at 68 centers across Asia, Australia, North America, and western Europe (n=202).
- Patients previously treated with trastuzumab and a taxane were randomly assigned to trastuzumab emtansine (3.6 mg/kg) plus atezolizumab (1200 mg) or to trastuzumab emtansine plus placebo.
- All study drugs were given intravenously every 3 weeks.
- Funding: F. Hoffmann-La Roche.
- Median follow-up, 8.5 months with atezolizumab and 8.4 months with placebo group.
- The atezolizumab group did not have superior PFS:
- Median PFS was 8.2 months for atezolizumab group vs 6.8 months for placebo.
- HR, 0.82 (P=.33).
- Most common ≥grade 3 AEs in atezolizumab vs placebo groups:
- Thrombocytopenia (13% vs 4%, respectively);
- Increased aspartate aminotransferase (8% vs 3%); and
- Anemia (5% vs 0%).
- Study ended prematurely.