An orally bioavailable selective agonist of the G protein-coupled estrogen receptor (G protein-coupled estrogen receptor 1; GPER; GPER1; GPR30), with potential immunomodulating and antineoplastic activities. Upon oral administration, LNS8801 targets, binds to and activates GPER. This activates GPER-mediated signaling and suppresses the expression of various tumor-associated genes, such as c-Myc and programmed cell death-ligand 1 (PD-L1). This leads to an inhibition of tumor cell proliferation. GPER activation may also induce immune memory. GPER is a membrane protein and a member of the G-protein coupled receptors (GPCRs) that are widely distributed in various tissues. GPER is a tumor suppressor in a wide range of cell cancer types.