Barecetamab is a reference antibody targeting ERBB3 (also known as HER3), a receptor tyrosine kinase involved in cell proliferation and survival signaling. It is primarily used in research and development of cancer therapeutics, especially in cancers where the HER3 pathway is overactive, such as certain breast, lung, gastric, and colorectal cancers. The antibody functions by blocking the activation of HER3, particularly by preventing its dimerization with other HER family members like HER2 or EGFR, which dampens downstream signaling pathways such as PI3K/AKT. This makes barecetamab a valuable tool in studying tumor growth inhibition and resistance mechanisms in HER-driven cancers. Due to its well-characterized binding and neutralizing properties, barecetamab serves as a benchmark in the development of biosimilars, immunoassays, and companion diagnostics. It is also employed in preclinical studies to evaluate the efficacy of combination therapies involving other targeted agents or chemotherapeutics. Its role in elucidating HER3 biology supports the design of next-generation biologics and antibody-drug conjugates.