Dr Damodaran on Futibatinib Plus Fulvestrant in FGFR1-Amplified HR+/HER2– Breast Cancer

Senthil Damodaran, MD, PhD, associate professor, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses the efficacy of futibatinib (Lytgobi) plus fulvestrant (Faslodex) in patients with FGFR1-amplified metastatic hormone receptor (HR)–positive, HER2-negative breast cancer according to findings from the phase 2 FOENIX-MBC2 trial (NCT04024436).

The phase 2, open-label, signal-seeking study assessed the efficacy and safety of futibatinib alone or in combination with fulvestrant in adult patients with locally advanced/metastatic HR-positive, HER2-negative breast cancer who harbored FGFR gene amplification, Damodaran begins. The study included 4 patient cohorts, one of which enrolled 22 patients with high-level FGFR1 amplification. All of these patients had previously received a CDK4/6 inhibitor and experienced disease progression on a different prior therapy. Patients in this arm had received a median number of 2.5 prior lines, including neoadjuvant therapies.

Final results from this cohort of patients treated with the combination regimen were presented at the 2023 San Antonio Breast Cancer Symposium. Futibatinib plus fulvestrant produced a median progression-free survival of 7.2 months (95% CI, 2.1%-7.6%) and a clinical benefit rate of 50% (95% CI, 28.2%-71.8%), he reports. The agent also produced a partial response rate of 18.2% (95% CI, 5.2%-40.3%), stable disease in 50% of patients, and disease progression in 27.3% of patients. The median duration of response was 6.3 months (95% CI, 3.3-16.7).

Overall, futibatinib and fulvestrant demonstrated high and encouraging antitumor activity in this patient population, Damodaran reports. Notably, the regimen's activity is comparable with historical data for fulvestrant alone in the post-CDK4/6 inhibitor setting. Future research is needed to elucidate the benefit of futibatinib for patients with HR-positive, HER2-negative breast cancer, he concludes.