title: Trastuzumab emtansine is active on HER-2 overexpressing NSCLC cell lines and overcomes gefitinib resistance.
abstract: BACKGROUND
  HER-2 represents a relatively new therapeutic target for non small cell lung cancer (NSCLC) patients. The incidence for reported HER-2 overexpression/amplification/mutations ranges from 2 to 20% in NSCLC. Moreover, HER-2 amplification is a potential mechanism of resistance to tyrosine kinase inhibitors of the epidermal growth factor receptor (EGFR-TKI) (about 10% of cases). T-DM1, trastuzumab emtansine is an antibody-drug conjugate composed by the monoclonal antibody trastuzumab and the microtubule polymerization inhibitor DM1. The activity of T-DM1 has been studied in breast cancer but the role of T-DM1 in lung cancer remains unexplored.
  
  
  METHODS
  Antiproliferative and proapoptotic effects of T-DM1 have been investigated in different NSCLC cell lines by MTT, crystal violet staining, morphological study and Western blotting. HER-2 expression and cell cycle were evaluated by flow cytometry and Western blotting. Antibody dependent cell cytotoxicity (ADCC) was measured with a CytoTox assay. Xenografted mice model has been generated using a NSCLC cell line to evaluate the effect of T-DM1 on tumor growth. Moreover, a morphometric and immunohistochemical analysis of tumor xenografts was conducted.
  
  
  RESULTS
  In this study we investigated the effect of T-DM1 in a panel of NSCLC cell lines with different HER-2 expression levels, in H1781 cell line carrying HER-2 mutation and in gefitinib resistant HER-2 overexpressing PC9/HER2cl1 cell clone. T-DM1 efficiently inhibited proliferation with arrest in G2-M phase and induced cell death by apoptosis in cells with a significant level of surface expression of HER-2. Antibody-dependent cytotoxicity assay documented that T-DM1 maintained the same activity of trastuzumab. Our data also suggest that targeting HER-2 with T-DM1 potentially overcomes gefitinib resistance. In addition a correlation between cell density/tumor size with both HER-2 expression and T-DM1 activity was established in vitro and in an in vivo xenograft model.
  
  
  CONCLUSIONS
  Our results indicate that targeting HER-2 with T-DM1 may offer a new therapeutic approach in HER-2 over-expressing lung cancers including those resistant to EGFR TKIs.
authors.forename: Daniele
authors.initials: D
authors.lastname: Cretella
authors.forename: Francesca
authors.initials: F
authors.lastname: Saccani
authors.forename: Federico
authors.initials: F
authors.lastname: Quaini
authors.forename: Caterina
authors.initials: C
authors.lastname: Frati
authors.forename: Costanza
authors.initials: C
authors.lastname: Lagrasta
authors.forename: Mara
authors.initials: M
authors.lastname: Bonelli
authors.forename: Cristina
authors.initials: C
authors.lastname: Caffarra
authors.forename: Andrea
authors.initials: A
authors.lastname: Cavazzoni
authors.forename: Claudia
authors.initials: C
authors.lastname: Fumarola
authors.forename: Maricla
authors.initials: M
authors.lastname: Galetti
authors.forename: Silvia
authors.initials: S
authors.lastname: La Monica
authors.forename: Luca
authors.initials: L
authors.lastname: Ampollini
authors.forename: Marcello
authors.initials: M
authors.lastname: Tiseo
authors.forename: Andrea
authors.initials: A
authors.lastname: Ardizzoni
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Petronini
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci 14, Parma, 43126, Italy. roberta.alfieri@unipr.it.
authors.forename: Roberta R
authors.initials: RR
authors.lastname: Alfieri
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005260:Female; D000077156:Gefitinib; D015870:Gene Expression; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008453:Maytansine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D011799:Quinazolines / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D000068878:Trastuzumab; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000077156:Gefitinib; D018796:Immunoconjugates; D008453:Maytansine; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human