RX608

RX608 is a potent and selective small molecule inhibitor of Son of Sevenless homolog 1 (SOS1), developed by Suzhou NeuPharma. SOS1 acts as a guanine nucleotide exchange factor (GEF) that facilitates the transition of RAS proteins (including KRAS, HRAS, and NRAS) from an inactive GDP-bound state to an active GTP-bound state. By inhibiting SOS1, RX608 prevents the activation of RAS and subsequently suppresses the downstream MAPK (mitogen-activated protein kinase) signaling pathway, which is a primary driver of cell proliferation and survival in many cancers. The drug is specifically designed to target tumors harboring mutations in the MAPK pathway, such as KRAS mutations. It is currently undergoing Phase 1 clinical evaluation for safety, tolerability, and preliminary efficacy in patients with advanced malignant solid neoplasms.