Taselisib + letrozole combination active in ER+, HER2− early breast cancer

  • Saura C & al.
  • Lancet Oncol
  • 8 Aug 2019

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

  • Adding taselisib to letrozole improved the objective response rate (ORR) in a phase 2 randomized trial of postmenopausal women with estrogen receptor (ER)-positive, HER2-negative early breast cancer.

Why this matters

Study design

  • Double-blind trial (n=334) conducted in 22 countries among 334 patients randomly assigned to 16 weeks of neoadjuvant letrozole (2.5 mg/day continuous) with placebo or oral taselisib (4 mg on a 5-days-on, 2-days-off schedule) for 16 weeks followed by surgery.
  • Coprimary outcomes were ORR and pathologic complete response (pCR).
  • Funding: Genentech; F. Hoffmann-La Roche.

Key results

  • Median follow-up was 4.9 months.
  • Taselisib-treated patients had a higher ORR, as assessed by MRI (50% vs 39%; OR=1.55, P=.049).
    • The taselisib subgroup with PIK3CA mutations also showed greater response (56% vs 38%; OR=2.03, P=.033).
  • No difference between groups in pCR across groups and across subsets with PIK3CA mutations.
  • Most frequent grade 3-4 adverse events were gastrointestinal (8%), infections (5%), and skin-subcutaneous tissue disorders (5%).

Limitations

  • Not powered to detect relapse-free survival.