Used in targeted cancer therapy, particularly for tumors overexpressing HER3 receptors. Binds to HER3 with high specificity, blocking ligand-induced activation and downstream signaling pathways like PI3K/AKT, which are involved in cell survival and proliferation. Investigated in clinical trials for cancers such as breast, lung, and colorectal, especially in combination with other targeted agents or chemotherapy. Shows potential in overcoming resistance to EGFR or HER2 inhibitors by suppressing compensatory HER3 signaling. Also utilized as a reference standard in preclinical research and assay development for evaluating other HER3-targeting therapeutics.