LOXO-783 + abemaciclib + fulvestrant

LOXO-783 + abemaciclib + fulvestrant is an investigational combination therapy being studied in clinical trials for patients with advanced breast cancer and other solid tumors harboring PIK3CA H1047R mutations. LOXO-783 is a mutant-selective, brain-penetrant, allosteric inhibitor of phosphoinositide 3-kinase alpha (PI3Kα), designed to target the H1047R mutation seen in 30–40% of PIK3CA-mutated breast cancers. Abemaciclib is a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, while fulvestrant is a selective estrogen receptor degrader (SERD). The combination aims to more effectively inhibit tumor cell proliferation and circumvent resistance mechanisms by simultaneously blocking PI3K signaling (with LOXO-783), cell cycle progression (with abemaciclib), and estrogen-driven signaling (with fulvestrant). The combination is currently being evaluated in Phase 1 clinical trials for PIK3CA-mutant, ER-positive, HER2-negative advanced breast cancer and other eligible solid tumors[1][2][3].