title: Combination of Gefitinib and Pemetrexed Prevents the Acquisition of TKI Resistance in NSCLC Cell Lines Carrying EGFR-Activating Mutation.
abstract: Development of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors is a clinical issue in patients with epidermal growth factor receptor gene (EGFR)-mutated non-small cell lung cancer (NSCLC). The aim of this study was to investigate the potential of combining gefitinib and pemetrexed in preventing the acquisition of resistance to EGFR tyrosine kinase inhibitors in NSCLC cell lines harboring EGFR exon 19 deletion.
  
  
  
  The effect of different combinatorial schedules of gefitinib and pemetrexed on cell proliferation, cell cycle, apoptosis, and acquisition of gefitinib resistance in PC9 and HCC827 NSCLC cell lines and in PC9 xenograft models was investigated.
  
  
  
  Simultaneous treatment with gefitinib and pemetrexed enhanced cell growth inhibition and cell death and prevented the appearance of gefitinib resistance mediated by T790M mutation or epithelial-to-mesenchymal transition (EMT) in PC9 and HCC827 cells, respectively. In PC9 cells and in PC9 xenografts the combination of gefitinib and pemetrexed, with different schedules, prevented gefitinib resistance only when pemetrexed was the first treatment, given alone or together with gefitinib. Conversely, when gefitinib alone was administered first and pemetrexed sequentially alternated, a negative interaction was observed and no prevention of gefitinib resistance was documented. The mechanisms of resistance that developed in vivo included T790M mutation and EMT. The induction of EMT was a feature of tumors treated with gefitinib when given before pemetrexed, whereas T790M was recorded only in tumors treated with gefitinib alone.
  
  
  
  The combination of gefitinib and pemetrexed is effective in preventing gefitinib resistance; the application of intermittent treatments requires that gefitinib not be administered before pemetrexed.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: La Monica
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Denise
authors.initials: D
authors.lastname: Madeddu
authors.affiliation: Medical Oncology Unit, University Hospital of Parma, Parma, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Tiseo
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Vivo
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy; Italian Workers' Compensation Authority Research Centre, University of Parma, Parma, Italy.
authors.forename: Maricla
authors.initials: M
authors.lastname: Galetti
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Cretella
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Mara
authors.initials: M
authors.lastname: Bonelli
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fumarola
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cavazzoni
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Falco
authors.affiliation: Department of Biomedical, Biotechnological, and Translational Sciences, University of Parma, Parma, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gervasi
authors.affiliation: Department of Biomedical, Biotechnological, and Translational Sciences, University of Parma, Parma, Italy.
authors.forename: Costanza Annamaria
authors.initials: CA
authors.lastname: Lagrasta
authors.affiliation: Medical Oncology Unit, University Hospital of Parma, Parma, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Naldi
authors.affiliation: Department of Pharmacy, University of Parma, Parma, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Barocelli
authors.affiliation: Division of Medical Oncology, Sant'Orsola-Malpighi University Hospital, Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ardizzoni
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Quaini
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Petronini
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy. Electronic address: roberta.alfieri@unipr.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Alfieri
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics*; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D009154:Mutation; D000068437:Pemetrexed / Q000008:administration & dosage; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D011799:Quinazolines / Q000008:administration & dosage
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000068437:Pemetrexed; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib
keywords: EGFR; Gefitinib; NSCLC; Pemetrexed; TKI resistance