Key clinical point: Compared with fulvestrant alone, addition of sapanisertib to fulvestrant led to numerical but not statistically significant improvement in progression-free survival (PFS) in postmenopausal women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (BC), but with increased toxicity.
Major finding: Median PFS was 3.5 months with only fulvestrant vs 7.2 months with fulvestrant+sapanisertib daily (QD; hazard ratio [HR], 0.77; 95% CI, 0.47-1.26) and 5.6 months with fulvestrant+sapanisertib weekly (QW; HR, 0.88; 95% CI, 0.53-1.45) arms. Fulvestrant+sapanisertib vs fulvestrant alone was associated with higher grade ≥3 treatment-related treatment-emergent adverse events (>50% vs none).
Study details: Findings are from a phase 2 study including 141 postmenopausal women with ER+/HER2− advanced or metastatic BC who were randomly assigned to fulvestrant, fulvestrant+sapanisertib QD, or fulvestrant+sapanisertib QW.
Disclosures: This study was funded by Millennium Pharmaceuticals. The authors declared serving in the advisory committee and speaker’s bureau and/or receiving consulting fees, grants, funds, honoraria, and travel expenses from Millennium Pharmaceuticals and other sources. Five authors declared being employees and/or shareholders of Millennium Pharmaceuticals.
Source: García-Sáenz J Á et al. Clin Cancer Res. 2022 Jan 3. doi: 10.1158/1078-0432.CCR-21-2652 .