|The following article features coverage from the European Society of Medical Oncology (ESMO) 2017 Congress in Madrid, Spain. Click here to read more of Cancer Therapy Advisor’s conference coverage.|
Abemaciclib plus letrozole or anastrozole is an effective treatment strategy for patients with HR-positive, HER2-negative advanced breast cancer who have not yet received systemic therapy, according to data presented at the European Society of Medical Oncology (ESMO) 2017 Congress in Spain.1
Abemaciclib is a CDK4/6 inhibitor effective among previously treated patients with advanced breast cancer. For the MONARCH 3 trial (ClinicalTrials.gov Identifier: NCT02246621), researchers compared the efficacy of abemaciclib plus anastrozole or letrozole vs placebo plus anastrozole or letrozole among patients not previously treated with a systemic therapy.
Of 493 enrolled women, 328 were randomly assigned to abemaciclib and 165 were assigned to placebo. All patients had HR-positive, HER2-negative advanced disease; 80.5% of patients had measurable disease and 27.4% received prior neoadjuvant aromatase inhibition.
The median progression-free survival (PFS) was not reached for abemaciclib vs 14.7 months for placebo (hazard ratio, 0.543; P = .000021). The objective response rate (ORR) was 59% in the abemaciclib group vs 44% for placebo.
Adverse events were, however, more common in the abemaciclib group: 81.3% of patients receiving abemaciclib had any-grade diarrhea vs 29.8% in the placebo group; 41.3% of patients receiving abemaciclib had neutropenia vs 1.9% in the placebo group.
The researchers concluded that “abemaciclib + NSAI [a non-steroidal aromatase inhibitor] demonstrated a tolerable safety profile and was an effective initial treatment for [patients] with HR+/HER2- [advanced breast cancer], significantly improving PFS and ORR.”
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- di Leo A, Toi M, Campone M, et al. MONARCH 3: Abemaciclib as initial therapy for patients with HR+/HER2- advanced breast cancer. Presented at: ESMO 2017 Congress; Madrid, Spain: September 8-12, 2017. Abstract 236O_PR.