Afuresertib plus fulvestrant for pretreated HR-positive, HER2-negative, advanced breast cancer: a phase Ib trial

This single-arm, phase Ib trial evaluated the antitumor activities and safety of afuresertib (a pan AKT inhibitor) plus fulvestrant for previously treated HR-positive, HER2-negative advanced breast cancer. Eligible patients received afuresertib at 125 mg/day and fulvestrant at 500 mg on days 1, 15, and 29, and every 28 days thereafter during safety run-in and, in the absence of serious toxicities, subsequent 4-week cycles. The trial enrolled 31 patients (median age 54 years; 30 women); 20 received prior CDK4/6 inhibitor therapy. The primary endpoint of investigators-assessed objective response rate was 25.8% (8/31; 90% CI 13.5-41.8). Nine patients (29.0%) had grade 3 or worse adverse events. No death due to adverse event occurred. In conclusion, afuresertib plus fulvestrant was well-tolerated and had promising antitumor activities against pretreated, advanced HR-positive, HER2-negative breast cancer, supporting further studies with randomized controlled trials. This trial is registered with ClinicalTrials.gov (NCT04851613).