PS031291

PS031291 is a small molecule antagonist of the C-C chemokine receptor type 1 (CCR1), originally developed by Pharmacopeia and subsequently by Ligand Pharmaceuticals following its acquisition of Pharmacopeia in late 2008. CCR1 is a G protein-coupled receptor primarily expressed on monocytes, macrophages, and T cells, where it mediates leukocyte chemotaxis and activation in response to pro-inflammatory chemokines such as CCL3 (MIP-1α) and CCL5 (RANTES). By inhibiting CCR1, PS031291 was designed to reduce the infiltration of inflammatory cells into tissues, potentially offering a therapeutic approach for various inflammatory and autoimmune conditions. The compound was nominated as a preclinical development candidate in early 2008, and GLP toxicology studies were initiated shortly thereafter, though clinical progression has not been extensively documented in later years.