MLN3897

MLN3897 (also known as AVE9897) is an orally bioavailable small molecule antagonist of the C-C chemokine receptor type 1 (CCR1). Developed by Millennium Pharmaceuticals in collaboration with Sanofi, it was designed to treat inflammatory conditions by blocking the migration of immune cells mediated by CCR1 ligands such as CCL3 (MIP-1α) and CCL5 (RANTES). The drug was primarily evaluated for the treatment of rheumatoid arthritis (RA). In a Phase IIa proof-of-concept trial, MLN3897 was administered to patients with active RA on stable methotrexate therapy. Although the drug achieved high receptor occupancy (≥90%) and was well-tolerated, it failed to demonstrate significant clinical efficacy compared to placebo, leading to the discontinuation of its development.