ASCO 2017 - High-risk breast cancer: pembrolizumab+standard therapy improved pathologic complete response rates

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  • At a maximum tolerated dose of pembrolizumab 200 mg every 3 wk for 4 cycles added to standard therapy in patients with HR+, HER2, and triple-negative breast cancer, the Bayesian probability of superior pathologic control rates was 99.0%.

Why this matters

  • Pembrolizumab is an anti-PD-1 antibody with single-agent activity in HER2 metastatic breast cancer.
  • ISPY-2 studies its activity in patients with HER2, HR+/HER2, and HR/HER2 cancers.
  • Tumors can coopt the PD-1 pathway to evade immune surveillance.

Study design

  • Multicenter phase 2 platform trial (n=2048).
  • Two groups: paclitaxel 80 mg/m2/wk×12 wk (n=180) vs paclitaxel+pembrolizumab 200 mg every 3 wk, 4 cycles (n=69), followed by doxorubicin and cyclophosphamide, standard dose.
  • Sponsor: QuantumLeap Healthcare Collaborative.

Key results

  • Bayesian model generates predictive probability distributions of estim...