HER2/neu

HER2/neu
Name	HER2/neu
Uniprot	P04626
Omim	164870
Location	17q12

HER2/neu HER2/neu is a receptor tyrosine kinase encoded by the ERBB2 gene, implicated in development and progression of several human cancers. It functions in cell signaling pathways that regulate proliferation and survival and is a clinically actionable biomarker in oncology. The gene and protein have been the focus of translational research, regulatory approvals, and landmark clinical trials that reshaped treatment standards.

Overview

HER2/neu is a member of the ErbB family alongside Epidermal growth factor receptor, ErbB3, and ErbB4, and participates in homo- and heterodimerization influencing downstream cascades such as the MAPK/ERK pathway and PI3K/AKT pathway. The locus on chromosome 17q12 has been studied in contexts ranging from Breast cancer to Gastric cancer and Ovarian cancer, with implications for prognosis and therapy in multicenter trials like those conducted by the National Cancer Institute and cooperative groups such as SWOG. Clinical practice guidelines from organizations including the American Society of Clinical Oncology and the College of American Pathologists define testing algorithms and treatment indications.

Structure and Function

The ERBB2 gene encodes a 185 kDa transmembrane glycoprotein with extracellular, transmembrane, and intracellular tyrosine kinase domains. Structural studies incorporating methods used at institutions like the Protein Data Bank landmarks and teams from Cold Spring Harbor Laboratory and Harvard Medical School revealed dimerization interfaces critical for activation. HER2/neu lacks a known high-affinity ligand, becoming activated primarily through heterodimerization with ligand-bound partners such as Epidermal growth factor-bound Epidermal growth factor receptor or neuregulin-bound ErbB3, impacting signaling nodes regulated by proteins studied at Broad Institute and Dana-Farber Cancer Institute. Post-translational modifications and endocytic trafficking observed in models from Johns Hopkins Hospital and MIT laboratories modulate receptor stability and signaling output.

Role in Cancer

Amplification and overexpression of ERBB2 drive oncogenic addiction in subsets of Breast cancer, notably in clinical cohorts reported from institutions like Memorial Sloan Kettering Cancer Center and trials such as the HERA trial. HER2-positive status correlates with aggressive histopathologic features observed in case series from Mayo Clinic and epidemiologic datasets from SEER Program. Beyond breast cancer, ERBB2 alterations appear in Gastric adenocarcinoma samples profiled by consortia including The Cancer Genome Atlas and in subsets of Non-small cell lung carcinoma where targeted inhibition has clinical relevance. Translational research at centers like Fred Hutchinson Cancer Center explored synthetic lethal interactions and combinatorial regimens informed by genomic profiling platforms developed at Genentech and Foundation Medicine.

Diagnostic Testing and Biomarkers

Detection of ERBB2 amplification/overexpression employs immunohistochemistry and in situ hybridization methods standardized by panels convened by American Society of Clinical Oncology and College of American Pathologists. Clinical laboratories accredited by Clinical Laboratory Improvement Amendments implement scoring systems derived from pivotal trials such as those coordinated by European Medicines Agency-linked studies. Companion diagnostics developed by companies including Roche and validated in multicenter evaluations guide eligibility for agents approved by regulatory bodies like the U.S. Food and Drug Administration. Emerging assays incorporate next-generation sequencing platforms from Illumina and circulating tumor DNA assays validated in cohorts from Johns Hopkins University to detect ERBB2 mutations, amplifications, and extracellular domain shedding implicated in resistance.

Targeted Therapies and Clinical Management

Therapeutic targeting of ERBB2 transformed management paradigms; monoclonal antibodies such as trastuzumab were developed in collaborations involving academic investigators at University of Pennsylvania and biotech firms leading to approvals by the U.S. Food and Drug Administration. Antibody–drug conjugates exemplified by ado-trastuzumab emtansine and trastuzumab deruxtecan were advanced through programs at Roche and Daiichi Sankyo, while small-molecule tyrosine kinase inhibitors like lapatinib and tucatinib were evaluated in randomized trials conducted by groups including ECOG-ACRIN. Multidisciplinary care pathways implemented at centers such as MD Anderson Cancer Center integrate surgery, systemic therapy, radiation oncology, and supportive care per guidelines from National Comprehensive Cancer Network.

Mechanisms of Resistance

Primary and acquired resistance mechanisms encompass ERBB2 extracellular domain mutations, kinase domain alterations profiled in cohorts from University of Cambridge, activation of bypass tracks including upregulation of MET or loss of tumor suppressors such as PTEN, and adaptive changes in immune microenvironment components studied at Yale University. Preclinical models from laboratories at Cold Spring Harbor Laboratory and clinical correlative studies from European Organisation for Research and Treatment of Cancer characterized intratumoral heterogeneity and clonal evolution under selective pressure from HER2-targeted agents. Combination strategies targeting parallel pathways or employing bispecific antibodies investigated by companies like Amgen aim to overcome these resistance modes.

History and Nomenclature

ERBB2 was initially identified through oncogene screens in viral systems and molecular cloning efforts at institutions including Stanford University and Salk Institute in the 1980s, contemporaneous with discovery work on Ras and Myc. The name "neu" derived from early rodent neuroblastoma studies at laboratories such as Max Planck Institute, while "HER2" reflects its homology to human epidermal growth factor receptor studied by research groups at Imperial College London. Clinical translation accelerated after pivotal randomized trials and regulatory approvals in the 1990s and 2000s, driven by collaborations among academic centers, pharmaceutical companies, and regulatory agencies including the European Medicines Agency and U.S. Food and Drug Administration.

Category:Oncogenes Category:Receptor tyrosine kinases Category:Breast cancer biomarkers