First-Line Abemaciclib Plus Endocrine Therapy Improves Efficacy Among Patients With HR-Positive, HER2-Negative Advanced Breast Cancer

According to results from the phase 2 ABIGAIL trial, first-line abemaciclib plus endocrine therapy improves efficacy compared to standard chemotherapy among patients with hormone receptor (HR)-positive, human epidermal growth factor receptor (HER2)-negative advanced breast cancer. 

These results were first presented by Juan De la Haba Rodríguez, MD, Reina Sofia University Hospital, Córdoba, Spain, at the 2024 European Society for Medical Oncology (ESMO) Congress in Barcelona, Spain. 

In this open-label, multicenter study, researchers enrolled 162 patients with aggressive, measurable disease who had received no prior systemic treatment in the advanced setting. Patients were randomized on a 1-to-1 basis to receive either 150 mg of twice daily abemaciclib in 28-day cycles plus investigator’s choice of endocrine therapy (letrozole or fulvestrant; n = 80) or paclitaxel followed by 12 weeks of abemaciclib and endocrine therapy (n = 82). The primary end point was 12-week objective response rate (ORR), assessed via blinded independent central review. A key secondary end point was safety. 

At analysis, 12-week ORR was 58.8% in the abemaciclib arm and 40.2% in the paclitaxel arm (odds ratio, 2.12; 95% confidence interval [CI], 1.13 to 3.96; P = .019). The most frequent treatment-emergent adverse events, occurring in ≥ 10% of patients, included neutropenia, leukopenia, alopecia, peripheral neuropathy, diarrhea, asthenia, nausea, neurotoxicity, and decreased appetite. 

As Dr De la Haba Rodríguez concluded, “the ABIGAIL trial demonstrated that abemaciclib combined with endocrine therapy shows superior efficacy at 12 weeks compared to standard chemotherapy as a front-line treatment strategy for [HR-positive, HER2-negative advanced breast cancer] patients with aggressive disease characteristics.” 

Source: 

De la Haba Rodríguez J, Cortes J, Di Cosimo S, et al. Randomized phase II study of abemaciclib plus endocrine therapy (ET) with or without a short course of induction paclitaxel in patients (pts) with previously untreated HR-positive/HER2-negative advanced breast cancer (HR+/HER2- ABC) with aggressive disease criteria. Presented at 2024 ESMO Congress. September 13-17, 2024. Abstract LBA23