A humanized immunoglobulin (Ig) G4 monoclonal antibody directed against toll-like receptor type 2 (TLR2), with potential anti-inflammatory and antineoplastic activities. Upon intravenous administration, OPN-305 binds to the ligand-binding site on the TLR2 receptor and blocks the activation of TLR2-mediated innate immunity signaling. This prevents the TLR2-mediated production of pro-inflammatory mediators and prevents inflammation. TLR2, a member of the TLR family primarily found on leukocytes, plays a key role in the activation of innate immunity; it is overexpressed in various inflammatory diseases and in certain types of cancer.