inavolisib + ribociclib + fulvestrant

A combination regimen of three targeted and endocrine agents: **inavolisib** (a PI3K alpha-selective inhibitor), **ribociclib** (a CDK4/6 inhibitor), and **fulvestrant** (a selective estrogen receptor degrader/SERD). This triplet regimen is designed to treat hormone receptor–positive (HR+), HER2-negative, PIK3CA-mutated endocrine-resistant advanced or metastatic breast cancer. Inavolisib provides mutant-selective, potent inhibition and degradation of PI3K alpha, ribociclib inhibits cell cycle progression by targeting CDK4/6, and fulvestrant antagonizes and degrades estrogen receptor signaling, addressing key mechanisms of endocrine resistance. The combination aims to prolong progression-free and overall survival in patients whose cancers harbor PIK3CA mutations and have progressed after endocrine therapy[1][2][3][4].