title: HER3 Targeting Sensitizes HNSCC to Cetuximab by Reducing HER3 Activity and HER2/HER3 Dimerization: Evidence from Cell Line and Patient-Derived Xenograft Models.
abstract: OBJECTIVE
  Our previous work suggested that HER3 inhibition sensitizes head and neck squamous cell carcinoma (HNSCC) to EGFR inhibition with cetuximab. This study aimed to define the role of HER3 in cetuximab resistance and the antitumor mechanisms of EGFR/HER3 dual targeting in HNSCC.
  
  
  METHODS
  We treated cetuximab-resistant HNSCC UMSCC1-C and parental UMSCC1-P cell lines with anti-EGFR antibody cetuximab, anti-HER3 antibody MM-121, and their combination. We assessed activities of HER2, HER3, and downstream signaling pathways by Western blotting and cell growth by sulforhodamine B (SRB) and colony formation assays. HER3-specific shRNA was used to confirm the role of HER3 in cetuximab response. The combined efficacy and alterations in biomarkers were evaluated in UMSCC1-C xenograft and patient-derived xenograft (PDX) models.
  
  
  RESULTS
  Cetuximab treatment induced HER3 activation and HER2/HER3 dimerization in HNSCC cell lines. Combined treatment with cetuximab and MM-121 blocked EGFR and HER3 activities and inhibited the PI3K/AKT and ERK signaling pathways and HNSCC cell growth more effectively than each antibody alone. HER3 knockdown reduced HER2 activation and resensitized cells to cetuximab. Cetuximab-resistant xenografts and PDX models revealed greater efficacy of dual EGFR and HER3 inhibition compared with single antibodies. In PDX tissue samples, cetuximab induced HER3 expression and MM-121 reduced AKT activity.
  
  
  CONCLUSIONS
  Clinically relevant PDX models demonstrate that dual targeting of EGFR and HER3 is superior to EGFR targeting alone in HNSCC. Our study illustrates the upregulation of HER3 by cetuximab as one mechanism underlying resistance to EGFR inhibition in HNSCC, supporting further clinical investigations using multiple targeting strategies in patients who have failed cetuximab-based therapy. Clin Cancer Res; 23(3); 677-86. ©2016 AACR.
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Qian
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Hongzheng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Pathology, Emory University, Atlanta, Georgia.
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Magliocca
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Sreenivas
authors.initials: S
authors.lastname: Nannapaneni
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: A R M Ruhul
authors.initials: AR
authors.lastname: Amin
authors.affiliation: Department of Radiation Oncology Emory University, Atlanta, Georgia.
authors.forename: Michael
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Department of Otolaryngology Emory University, Atlanta, Georgia.
authors.forename: Mihir
authors.initials: M
authors.lastname: Patel
authors.affiliation: Department of Otolaryngology Emory University, Atlanta, Georgia.
authors.forename: Mark
authors.initials: M
authors.lastname: El-Deiry
authors.affiliation: Department of Otolaryngology Emory University, Atlanta, Georgia.
authors.forename: J Trad
authors.initials: JT
authors.lastname: Wadsworth
authors.affiliation: Department of Biostatistics and Bioinformatics, Emory School of Public Health, Emory, University, Atlanta, Georgia.
authors.forename: Zhengjia
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Fadlo R
authors.initials: FR
authors.lastname: Khuri
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia.
authors.forename: Dong M
authors.initials: DM
authors.lastname: Shin
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia. gzchen@emory.edu NFSABA@emory.edu.
authors.forename: Nabil F
authors.initials: NF
authors.lastname: Saba
authors.affiliation: Department of Hematology and Medical Oncology, Winship Cancer Institute at Emory, University School of Medicine, Atlanta, Georgia. gzchen@emory.edu NFSABA@emory.edu.
authors.forename: Zhuo G
authors.initials: ZG
authors.lastname: Chen
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000074322:Antineoplastic Agents, Immunological / Q000494:pharmacology* / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology*; D000068818:Cetuximab / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D019281:Dimerization; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000502:physiology; D004790:Enzyme Induction / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006258:Head and Neck Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D008819:Mice, Nude; D016513:Mice, SCID; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D011487:Protein Conformation / Q000187:drug effects; D034622:RNA Interference; D011897:Random Allocation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry*; D020893:Receptor, ErbB-3 / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects; D014410:Tumor Stem Cell Assay; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000074322:Antineoplastic Agents, Immunological; D000068818:Cetuximab; D009363:Neoplasm Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; C000589319:seribantumab; C508053:ERBB2 protein, human; C581292:ERBB3 protein, human