RLY-5836 + fulvestrant

RLY-5836 + fulvestrant is a combination therapy under investigation for the treatment of advanced or metastatic breast cancer, particularly in patients with hormone receptor-positive (HR+), HER2-negative tumors harboring PIK3CA mutations. RLY-5836 is an orally bioavailable, small molecule inhibitor that selectively targets mutant forms of the phosphatidylinositol 3-kinase alpha (PI3Kα) catalytic subunit, including common oncogenic mutations such as PIK3CA E542K, E545K, and H1047X. Fulvestrant is a selective estrogen receptor degrader (SERD) that antagonizes and degrades the estrogen receptor. The combination aims to inhibit both PI3K-driven signaling pathways and estrogen receptor-mediated tumor growth. The regimen has been evaluated in Phase 1 clinical trials to determine safety, tolerability, pharmacokinetics/dynamics, and preliminary anti-tumor activity in patients with advanced solid tumors or breast cancer[1][2][5].