BR3E4

BR3E4 is a monoclonal rat anti-idiotypic antibody (Ab2) developed as an active immunotherapy agent. It is designed to target the monoclonal antibody CO17-1A (Ab1), which itself targets the colorectal carcinoma-associated CO17-1A/GA733 antigen. The primary mechanism of BR3E4 is to induce the production of anti-anti-idiotypic antibodies (Ab3) in patients. These Ab3 antibodies then specifically bind to the CO17-1A/GA733 antigen expressed on tumor cells, aiming to modulate the patient's immune response against their colorectal tumors. BR3E4 has been investigated in various formulations, including as intact IgG and as F(ab')2 fragments, sometimes conjugated to Keyhole Limpet Hemocyanin (KLH) and precipitated with aluminum-hydroxide (alum), to optimize the induction of immune responses. It has been evaluated in a Phase I clinical trial for patients with metastatic colorectal carcinoma.