Erb-b2 receptor tyrosine kinase 2

Overview

Erb-b2 receptor tyrosine kinase 2 (ERBB2), commonly designated HER2 (Human Epidermal Growth Factor Receptor 2), is a transmembrane receptor tyrosine kinase belonging to the ErbB/HER family of epidermal growth factor receptors. Unlike other members of this family, HER2 lacks a known endogenous ligand and instead functions primarily as a preferred dimerization partner for the remaining receptors (EGFR/HER1, HER3, and HER4). Upon heterodimerization—most notably with HER3—HER2 undergoes conformational activation that initiates downstream signaling through the RAS/MAPK, PI3K/AKT, and JAK/STAT3 pathways, driving cellular proliferation, survival, differentiation, and migration. The ERBB2 gene is located on chromosome 17q12 and encodes a 185 kDa glycoprotein comprising an extracellular domain, a single transmembrane segment, and an intracellular kinase domain. Amplification or overexpression of ERBB2 is a well-characterized oncogenic event detected across multiple tumor types, most prominently breast and gastric cancers, where it correlates with aggressive disease biology, elevated recurrence rates, and diminished overall survival.

The clinical significance of HER2 derives both from its value as a diagnostic and prognostic biomarker and from its utility as a therapeutic target. Overexpression of HER2 protein or amplification of the ERBB2 gene defines a molecularly distinct cancer subtype amenable to targeted intervention. The advent of anti-HER2 monoclonal antibodies such as trastuzumab and pertuzumab, small-molecule tyrosine kinase inhibitors (TKIs), and more recently antibody-drug conjugates (ADCs) such as trastuzumab deruxtecan (T-DXd) and ado-trastuzumab emtansine (T-DM1) has transformed the therapeutic landscape for HER2-positive malignancies. Ongoing research continues to expand the targetable indication set, optimize combination strategies, and address mechanisms of acquired resistance.

Focus of Latest Publications

Recent publications investigating Erb-b2 receptor tyrosine kinase 2 (HER2) as a therapeutic target demonstrate diverse and advancing approaches across multiple cancer types. Antibody-drug conjugate (ADC) technology remains a prominent focus, with novel engineering strategies including site-specific trastuzumab Fab-based ADCs conjugated with DM1 using peptide ligase (butelase-1) to achieve homogeneous drug-to-antibody ratios and improved tumor penetration relative to conventional IgG formats; fusion with albumin-binding domains further extended serum persistence and enhanced tumor growth inhibition in HER2-positive xenografts. Zanidatamab, a dual HER2-targeted bispecific antibody, showed encouraging efficacy when combined with chemotherapy, with or without the checkpoint inhibitor tislelizumab, in HER2-positive gastroesophageal adenocarcinoma. trastuzumab deruxtecan (T-DXd) demonstrated synergistic tumor growth inhibition when combined with pertuzumab in preclinical models of HER2-positive gastric cancer through enhanced HER2-HER3 pathway disruption and membrane internalization. pembrolizumab combined with trastuzumab and platinum-based chemotherapy achieved a median overall survival of 20 months in unresectable or metastatic HER2-positive gastric/gastroesophageal junction cancer, with benefits particularly pronounced in patients with elevated PD-L1 combined positive score.

Targeted protein degradation and immunological approaches represent emerging therapeutic modalities. The UPTAB platform achieved simultaneous degradation of HER2 alongside EGFR and c-MET across cancer cell lines and demonstrated approximately 80% tumor growth inhibition in breast cancer xenografts. HER2-targeted chimeric antigen receptor T-cell therapy was enhanced through engineering antigen-inducible interleukin-12 secretion, which augmented cytotoxicity across both high- and low-antigen-density tumors while maintaining proliferative capacity. A therapeutic vaccine targeting HER2 alongside IGFBP-2 and IGF-IR was evaluated in ductal carcinoma in situ for preventing progression to invasive breast cancer. HER2-selective tyrosine kinase inhibitors achieved substantial activity in HER2-mutant non-small cell lung cancer; zongertinib demonstrated a 76% objective response rate and 14.4-month median progression-free survival, substantially exceeding chemotherapy outcomes. Novel covalent dual EGFR/HER2 inhibitors showed potent antiproliferative effects in lung and breast cancer cell lines through irreversible kinase inhibition, inducing cell cycle arrest, apoptosis, and reactive oxygen species production.

Clinical application of HER2-targeted therapies demonstrates real-world efficacy and heterogeneous outcomes across disease contexts. Real-world treatment patterns in HER2-positive locally advanced unresectable or metastatic gastric/gastroesophageal junction cancer documented variable HER2 testing practices and clinical outcomes. A neoadjuvant randomized trial compared taxane plus trastuzumab-pertuzumab combinations with or without carboplatin in stage II-III HER2-positive breast cancer. Circulating tumor DNA minimal residual disease assessment emerged as a potentially superior risk stratification tool in HER2-positive breast cancer patients receiving neoadjuvant therapy. HER2-targeted therapies were identified as viable approaches in previously understudied malignancies, including HER2-amplified biliary tract cancer, ERBB2-overexpressing desmoplastic small round cell tumors (where trastuzumab deruxtecan produced long-lasting responses), and HER2-mutant colorectal cancer.

Mechanistic investigations revealed insights into HER2 function and therapeutic response. Biophysical characterization of cancer-associated ErbB2 missense mutations (R143Q, R678Q, V842I) demonstrated that single amino acid substitutions accelerate lateral receptor diffusion and promote a pre-dimerized state without inducing growth factor-independent activation, suggesting enhanced responsiveness to ligand engagement. In HER2-driven mammary tumorigenesis, despite downregulation of mitochondrial genes and oxidative phosphorylation subunits, mitochondrial respiration was markedly elevated; lapatinib-mediated HER2 kinase inhibition attenuated this elevated respiration, implicating HER2 signaling in metabolic rewiring independent of mitochondrial abundance. Computational and machine learning-driven antibody design identified HER2-binding antibodies with enhanced tumoricidal activity compared to Herceptin through simultaneous optimization of binding affinity and immunogenicity. Spatial immune signatures derived from trastuzumab-treated HER2-positive breast cancers predicted treatment response and identified patients most likely to benefit from HER2-directed therapy.

Key Publications

• NEWJul Site-specific trastuzumab Fab-DM1 via butelase-1 with ABD fusion for potent HER2-positive tumor control. (Medical oncology (Northwood, London, England), 2026, PMID 42384122): "The conjugate selectively killed HER2-positive cells in vitro while sparing HER2-negative controls."
• NEWJun Deep-Learning Solution Providing Molecular Marker Subtyping of Breast Cancer Whole Slide Images: Protocol for a UK Clinical Service Evaluation Study. (JMIR research protocols, 2026, PMID 42302265): "...requires additional testing for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) status at the time of histological diagnosis."
• NEWJun Real-world clinical characteristics and outcomes in patients with HER2-mutant non-small cell lung cancer (NSCLC) who received second-line treatment: A nationwide database analysis in Japan. (Lung cancer (Amsterdam, Netherlands), 2026, PMID 42263332): "Although human epidermal growth factor receptor 2 (HER2)-targeted therapies have been approved for HER2-mutant NSCLC, real-world outcome data especially in the second-line setting remains limited."
• Jan Interplay of the IGFBP-3 polymorphism and serum levels of IGF-1/IGFBP-3 with hormone receptor subtypes in patients with breast cancer among Palestinian women. (PloS one, 2026, PMID 42224209): "This study aimed to investigate the relationships between serum levels of insulin-like growth factor binding protein 3 (IGFBP-3), insulin-like growth factor 1 (IGF-1), the IGFBP-3 A-202C polymorphism and hormone receptor subtypes: estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) with respect to breast cancer risk in Palestinian women."
• May Real-World Treatment Patterns, HER2 Testing Practices, and Clinical Outcomes in HER2-Positive Locally Advanced or Metastatic Gastric or Gastroesophageal Junction Cancer. (Advances in therapy, 2026, PMID 42217113): "This study aimed to assess real-world treatment patterns, human epidermal growth factor receptor 2 (HER2) testing, and clinical outcomes in patients with HER2-positive locally advanced unresectable or metastatic gastric or gastroesophageal junction cancer (GC/GEJC) in China."
• May Zanidatamab with and without Tislelizumab in HER2-Positive Gastroesophageal Cancer. (The New England journal of medicine, 2026, PMID 42202319): "Zanidatamab, a dual human epidermal growth factor receptor 2 (HER2)-targeted bispecific antibody, plus chemotherapy both with and without tislelizumab (anti-programmed death 1), showed encouraging efficacy and safety as first-line therapy in phase 2 studies involving patients with HER2-positive gastroesophageal adenocarcinoma."
• May Placental transcriptome profiling and immune signature differences in pregnancies with and without gestational diabetes mellitus: An observational study. (Medicine, 2026, PMID 42175401): "In contrast, LEP and ERBB2 were downregulated in GDM placentas."
• May A Plug-and-Play Platform for Customizing Multivalent Degraders and Degrader-Drug Conjugates. (Advanced science (Weinheim, Baden-Wurttemberg, Germany), 2026, PMID 42138807): "Type-II and Type-III UPTAB enabled simultaneous degradation of EGFR/c-MET, EGFR/PD-L1, and EGFR/c-MET/HER2."
• May Feasibility study of the Four-Session Cognitive-Behavioral Therapy-based Psychological Intervention Program for women with HER2-positive metastatic breast cancer. (Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 2026, PMID 42141145): "Although targeted therapies have prolonged survival in human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer, the resulting chronic disease trajectory is frequently accompanied by substantial psychological burden."
• Jun Highlights of the San Antonio breast cancer symposium 2025 (Part 2). (Future oncology (London, England), 2026, PMID 42125775): "antibody-drug conjugates for advanced human epidermal growth factor receptor 2 (HER2) positive/negative disease,"