ASCO 2019 — Advanced breast cancer: ribociclib+endocrine therapy dramatically increases OS in young women


  • Debra Gordon
  • Oncology Conference reports
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Takeaway

  • Ribociclib in combination with endocrine therapy (ET) improved OS in premenopausal women with HR+/HER2 advanced breast cancer.

Why this matters

  • This is the first time a statistically significant improvement in OS has been observed with a CDK4/6 inhibitor with ET in HR+/HER2 advanced breast cancer.
  • Young women with breast cancer tend to have poorer prognoses and more aggressive cancer compared with older women, yet premenopausal patients are underrepresented in clinical trials.

Study design

  • Phase 3 MONALEESA-7 study (NCT02278120).
  • 672 premenopausal women with HR+/HER2 advanced breast cancer randomly assigned to ribociclib or placebo, plus goserelin and ET (either nonsteroidal aromatase inhibitor [NSAI] or tamoxifen).
  • Primary endpoint: protocol-specified OS.
  • Median follow-up: 34.6 months.
  • Funding: Novartis Pharmaceuticals.

Key results

  • OS with ribociclib plus ET crossed the prespecified stopping boundary for superior efficacy compared with a median OS of 40.9 months for placebo (HR, 0.712; 95% CI, 0.54-0.95; P=.00973).
  • Approximate 29% relative reduction in risk for death in the ribociclib group.
  • Approximate 30% relative reduction in risk for death in ribociclib plus NSAI compared with placebo (70.2% OS rate vs 46%; HR, 0.699; 95% CI, 0.50-0.98).
  • Treatment ongoing in 35% of patients in the ribociclib group vs 17% placebo.

Limitations

  • None listed.

Expert commentary

  • "This is the largest study in recent memory that focused exclusively on premenopausal women and shows that they, too, benefit from this class of drugs in a remarkable way," said Harold J. Burstein, MD, PhD, from the Dana-Farber Cancer Institute, Boston, Massachusetts. Dr. Burstein was not involved in the study.

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