Endocrine therapy (ET) is the preferred treatment for HR+/HER2- advanced breast cancer. However, patients with visceral crisis or severe symptoms will usually need induction chemotherapy to achieve rapid disease control. Cyclin dependent kinases 4/6 inhibitors have been able to improve effectiveness of ETs in all subgroups of HR+/HER2- breast cancer, demonstrating impressive overall response. Specifically, adding abemaciclib to ET has shown the largest benefit for patients that have characteristics of poor prognosis.
The ABIGAIL trial aims to provide consistent evidence the abemaciclib added to ET is non-inferior to paclitaxel in terms of overall response (OR) in frontline therapy for patients with HR+/HER2- advanced breast cancer and poor prognostic characteristics, in hopes of offering these patients a chemotherapy-free treatment. To be included in the trial, patients must be female or male 18 years or older, with HR+/HER2- advanced breast cancer, have received no prior systemic therapy, have an ECOG status of 0 or 1, and measurable disease per RECISIT 1.1. In addition, they must have one of the following characteristics: visceral disease, high histological grade and/or PgR-, LDH > 1.5 x ULN, or relapsed while on or less than 36 months of adjuvant ET.
The study is a multicenter, randomized, open label, phase 2 trial. Arm A of the study is receiving abemaciclib plus ET for 12 weeks, whereas Arm B is receiving paclitaxel for 12 weeks, at which time they will switch over to abemaciclib plus ET. If patients in Arm B experience toxicity or disease progression, they can cross over to Arm A at the discretion of the clinician.
Tumors are being assessed by CT and MRI every three weeks. The primary endpoint for the trial is overall response rate (ORR) at 12 weeks. The study is also assessing any prognostic biomarkers of response through pharmacodynamic changes in blood and tissue, analysis of the gut microbiome, and metabolomic profiling of stool samples.
ABIGAIL is currently recruiting 160 patients in 22 institutions in Spain as well as in 4 sites in Italy, and 4 sites Portugal. Contact us if you want more information about this trial!