HER2+ metastatic breast cancer: atezolizumab fails to improve PFS in phase 2 KATE2

  • Emens LA & al.
  • Lancet Oncology
  • 1 Oct 2020

  • curated by Miriam Davis, PhD
  • Univadis Clinical Summaries
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Takeaway

  • 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.

Study design

  • 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.

Key results

  • 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%).

Limitations

  • Study ended prematurely.