Abstract
In the global CAPItello-291 randomized phase 3 study (NCT04305496) in patients with hormone receptor-positive/HER2-negative advanced breast cancer and progression during/after aromatase inhibitor treatment, capivasertib-fulvestrant significantly improved progression-free survival (PFS) in the overall population and patients with PIK3CA/AKT1/PTEN-altered tumors versus placebo-fulvestrant. We assessed efficacy and safety of capivasertib-fulvestrant in a prespecified exploratory analysis of a Chinese cohort (n = 24) and extended study with the same protocol (n = 110). Clinically meaningful PFS benefit for capivasertib-fulvestrant was observed in the overall population (median PFS: 6.9 [capivasertib-fulvestrant] versus 2.8 [placebo-fulvestrant] months; hazard ratio 0.51, 95% CI 0.34-0.76), patients with PIK3CA/AKT1/PTEN-altered tumors (n = 46; 5.7 versus 1.9 months; hazard ratio 0.41, 95% CI 0.19-0.85) and PIK3CA/AKT1/PTEN-non-altered tumors (patients with confirmed next-generation sequencing results [n = 68]; 9.2 versus 2.7 months; hazard ratio 0.38; 95% CI 0.21-0.68). The most frequent adverse events (AEs) with capivasertib-fulvestrant were diarrhea (60.6% versus 11.3% with placebo-fulvestrant) and hyperglycemia (57.7% versus 17.7%). AEs leading to capivasertib-fulvestrant discontinuation were reported in 11.3% of patients versus 3.2% for placebo-fulvestrant. The benefit-risk profile of capivasertib-fulvestrant in the Chinese cohort was favorable; further exploration in patients with PIK3CA/AKT1/PTEN-non-altered tumors is warranted.