title: Epidermal growth factor receptor dimerization status determines skin toxicity to HER-kinase targeted therapies.
abstract: Skin toxicity, a common drug-related adverse event observed in cancer patients treated with epidermal growth factor receptor (EGFR)-directed therapies is rarely seen with therapies targeting HER2. This study reports the significance of the EGFR and HER2 dimerization status in skin with regard to these dermatologic side effects. We demonstrate the differential effect of HER-directed therapies on the ligand driven activation status of EGFR, HER2 and MAPK in normal human epidermal keratinocytes. EGFR-directed therapies, such as gefitinib and cetuximab, inhibited ligand-induced activation of EGFR and MAPK in human keratinocytes. Pertuzumab, an antibody interfering with functional HER2 heterodimerization, failed to block ligand-induced HER signaling in primary keratinocytes. Using a novel proximity-based dimerization assay (eTagtrade mark) we show that EGFR homodimers are the predominant HER dimer pair in normal primary kertinocytes and in normal skin tissue from 16 patients with solid malignancies. The presence of [p]EGFR and [p]MAPK, but the absence of [p]HER2, demonstrates productive signaling via EGFR but not HER2 in human skin. These data illustrate the importance of the EGFR dimerization partner in human skin and suggests that inhibition of EGFR homodimer signaling rather than EGFR/HER2 heterodimer signaling maybe the key molecular event determining dermatologic toxicity discrepancies observed between EGFR-targeted versus HER2-targeted therapies.
authors.affiliation: Louis Warschaw Prostate Cancer Center, Cedar-Sinai Medical Center, 8631 West Third Street, Suite 1001E, Los Angeles, CA 90048, USA.
authors.forename: I
authors.initials: I
authors.lastname: Laux
authors.forename: A
authors.initials: A
authors.lastname: Jain
authors.forename: S
authors.initials: S
authors.lastname: Singh
authors.forename: D B
authors.initials: DB
authors.lastname: Agus
mesh_terms: D000911:Antibodies, Monoclonal / Q000009:adverse effects*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000009:adverse effects*; D018929:Cell Culture Techniques; D000068818:Cetuximab; D019281:Dimerization; D066246:ErbB Receptors / Q000187:drug effects / Q000502:physiology*; D005076:Exanthema / Q000139:chemically induced* / Q000503:physiopathology*; D000077156:Gefitinib; D006801:Humans; D015603:Keratinocytes / Q000502:physiology; D008024:Ligands; D011799:Quinazolines / Q000009:adverse effects*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000068818:Cetuximab; D066246:ErbB Receptors; D000077156:Gefitinib; D008024:Ligands; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; C485206:pertuzumab