Rb9

Rb9 is a cyclic peptide anticancer agent being developed by Recepta Biopharma. It is derived from the VHCDR3 (variable heavy chain complementarity-determining region 3) of the RebMab200 humanized monoclonal antibody, which is directed against the NaPi2B sodium-phosphate transport protein. Rb9 has demonstrated anti-metastatic activity in preclinical studies, showing protective effects in melanoma, colon cancer, and pancreatic cancer models. Its mechanism of action involves multiple pathways, including immunomodulatory effects on dendritic cells and macrophages (promoting M1-type conversion), and interactions with Heat Shock Protein 90 (Hsp90), adhesion G-protein coupled receptors, and the MIF-CD74 pathway. Rb9 inhibits tumor cell migration and invasion and reduces metastatic nodules.