HER2 receptors are transmembrane proteins with signal transduction potential due to tyrosine kinase activity . The structure of HER2 receptors contains a ligand-binding domain (extracellular), a single transmembrane helix, a tyrosine kinase domain (intracellular), and a Cterminal tail (intracellular) . HER2, unlike other HER family receptors, does not have a known ligand . Instead, it forms heterodimers with different receptors in the HER family (HER1, HER3, HER4) that are activated by their ligands . HER2 plays a vital part in cell growth, differentiation, and survival. Its heterodimer formation enhances these receptor complexes' signaling potency . This activates intracellular pathways such as the MAPK and PI3K/AKt pathways, helping cell multiplication . However, the overexpression/amplification of the gene controlling HER2 expression is evident in multiple cancers, most notably in breast cancer, causing aggressive tumor growth and poor prognosis . Trastuzumab (Herceptin) and other targeted therapies are designed to inhibit the signaling of the HER2 receptor, affecting the development of HER-2-positive tumors . Although many patients with HER2-positive malignancies respond well to Herceptin (trastuzumab), other people eventually develop resistance to the medication.