title: Optimizing treatment of metastatic colorectal cancer patients with anti-EGFR antibodies: overcoming the mechanisms of cancer cell resistance.
abstract: BACKGROUND
  A number of anti-EGFR monoclonal antibodies (mAbs) have been recently developed for the treatment of refractory metastatic colorectal cancer (mCRC). These mAbs, blocking ligand/receptor interactions, exert their biological activity via multiple mechanisms, including inhibition of cell cycle progression, potentiation of cell apoptosis, inhibition of angiogenesis, tumor cell invasion and metastasis and, potentially, induction of immunological effector mechanisms.
  
  
  METHODS
  Cetuximab is an anti-EGFR mAb currently used in mCRC treatment. Despite the evidence of efficacy of cetuximab in the treatment of mCRC patients, the observation of low response rates was the proof of concept of resistance to anti-EGFR mAbs treatment. An increasing number of molecular alterations have been more recently hypothesized to be involved in resistance to anti-EGFR mAbs in CRC: mutations in BRAF, NRAS and PIK3CA, loss of expression of PTEN and, now, activation of HER2 signaling through HER2 gene amplification and/or increased heregulin stimulation.
  
  
  CONCLUSIONS
  This review focuses on the development of new strategies such as combination with other agents blocking alternative escape pathways, cancer cell prioritization hyperactivating EGFR pathway, combination with immune system, development of nanotech devices to increase efficacy of antibody-based therapy and overcome the mechanisms of cancer cell resistance.
authors.affiliation: Oncologia Medica, Dipartimento Medico-Chirurgico di Internistica Clinica e Sperimentale F. Magrassi e A. Lanzara, Seconda Università degli Studi di Napoli, Via S. Pansini 5, 80131 Napoli, Italia.
authors.forename: Teresa
authors.initials: T
authors.lastname: Troiani
authors.forename: Silvia
authors.initials: S
authors.lastname: Zappavigna
authors.forename: Erika
authors.initials: E
authors.lastname: Martinelli
authors.forename: Santolo R
authors.initials: SR
authors.lastname: Addeo
authors.forename: Paola
authors.initials: P
authors.lastname: Stiuso
authors.forename: Fortunato
authors.initials: F
authors.lastname: Ciardiello
authors.forename: Michele
authors.initials: M
authors.lastname: Caraglia
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D002471:Cell Transformation, Neoplastic; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D019008:Drug Resistance, Neoplasm / Q000276:immunology*; D066246:ErbB Receptors / Q000276:immunology*; D011905:Genes, ras; D006801:Humans; D009154:Mutation; D009362:Neoplasm Metastasis; D011379:Prognosis
chemical_list: D000911:Antibodies, Monoclonal; D066246:ErbB Receptors