MONARCH 2: Abemaciclib in Combination With Fulvestrant in Women With HR+/HER2− Advanced Breast Cancer Who Had Progressed While Receiving Endocrine Therapy
- Study type
- Clinical trial
- Study name
- MONARCH 2
- Phase
- Phase 3
- Design
- International, randomised (2:1), double-blind, placebo-controlled trial
- Sample size
- 669 patients
- Source
- JCO · 2017
- Trial registration
- NCT02107703
In plain words
In this study, women with advanced hormone-positive, HER2-negative breast cancer that had grown despite hormone therapy received either fulvestrant with the drug abemaciclib, or fulvestrant with a placebo (dummy pill). Adding abemaciclib lengthened the time the disease stayed under control without getting worse, from a typical 9.3 months to 16.4 months, and tumours shrank in more patients. Diarrhoea and a drop in white blood cells (neutropenia) were among the most common side effects. Whether this treatment is right for each patient is decided by the treating doctor.
Key results
Treatment arms and regimens
Abemaciclib 150 mg twice daily continuously, plus fulvestrant 500 mg (per label). Number of patients: 446.
Placebo twice daily (on the same schedule as abemaciclib) plus fulvestrant 500 mg (per label). Number of patients: 223.
Source of the regimen details: Abstract of the paper
Doses are given for the information of specialists, as in this study’s protocol, and are not a prescription. Every drug must be prescribed by the treating physician for the individual patient.
Study population
Women with hormone receptor-positive, HER2-negative advanced breast cancer whose disease had progressed on neoadjuvant or adjuvant endocrine therapy, within 12 months or less of the end of adjuvant endocrine therapy, or on first-line endocrine therapy for metastatic disease.
Endpoints
Primary endpoint: investigator-assessed progression-free survival (PFS). Key secondary endpoints: overall survival, objective response rate (ORR), duration of response, clinical benefit rate, quality of life and safety.
Safety and side effects
The most common adverse events with abemaciclib versus placebo: diarrhoea (86.4% versus 24.7%), neutropenia (46.0% versus 4.0%), nausea (45.1% versus 22.9%) and fatigue (39.9% versus 26.9%). Rates of grade 3 or higher adverse events are not given in the abstract.
Clinical significance and place in guidelines
According to the abstract, adding abemaciclib to fulvestrant in women with HR-positive/HER2-negative advanced breast cancer progressing on endocrine therapy significantly improved PFS and ORR, with a tolerable safety profile. Overall survival results are not reported in the abstract. Regulatory approvals and guideline recommendations should be checked in current sources.
Limitations
The abstract does not report overall survival results. The primary endpoint was investigator-assessed. Rates of grade 3 or higher adverse events and quality-of-life results are not given in the abstract and should be checked in the full text. Diarrhoea and neutropenia were much more common in the abemaciclib group.
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.