GS-986

**GS-986** is an investigational oral small molecule Toll-like receptor 7 (TLR7) agonist developed by Gilead Sciences as an immune stimulant and adjuvant. It activates plasmacytoid dendritic cells (pDCs) to express OX40L, produce IL-6 and IL-12, thereby inducing differentiation of follicular helper T cells (Tfh, CXCR5+ PD-1+ CD4+) from naive CD4+ T cells and promoting antigen-specific B-cell production, including hepatitis B surface antigen (HBsAg)-specific antibodies. In preclinical studies, it induces transient viremia, activates innate and adaptive immune cells, reduces viral reservoirs in SIV-infected rhesus macaques on ART, and enhances immune responses when combined with broadly neutralizing antibodies, supporting potential roles in functional cures for chronic viral infections like HIV and HBV.[1][2][3]