Detection of EGFR mutations with mutation-specific antibodies in stage IV non-small-cell lung cancer
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RESEARCH
Open Access
Detection of EGFR mutations with mutation-specific antibodies in stage IV non-small-cell lung cancer Sara Simonetti1, Miguel Angel Molina1, Cristina Queralt2, Itziar de Aguirre2, Clara Mayo1, Jordi Bertran-Alamillo1, José Javier Sanchez3, Jose Luis Gonzalez-Larriba4, Ulpiano Jimenez5, Dolores Isla6, Teresa Moran2, Santiago Viteri1, Carlos Camps7, Rosario Garcia-Campelo8, Bartomeu Massuti9, Susana Benlloch1, Santiago Ramon y Cajal1,10, Miquel Taron1,2*, Rafael Rosell1,2
Abstract Background: Immunohistochemistry (IHC) with mutation-specific antibodies may be an ancillary method of detecting EGFR mutations in lung cancer patients. Methods: EGFR mutation status was analyzed by DNA assays, and compared with IHC results in five non-small-cell lung cancer (NSCLC) cell lines and tumor samples from 78 stage IV NSCLC patients. Results: IHC correctly identified del 19 in the H1650 and PC9 cell lines, L858R in H1975, and wild-type EGFR in H460 and A549, as well as wild-type EGFR in tumor samples from 22 patients. IHC with the mAb against EGFR with del 19 was highly positive for the protein in all 17 patients with a 15-bp (ELREA) deletion in exon 19, whereas in patients with other deletions, IHC was weakly positive in 3 cases and negative in 9 cases. IHC with the mAb against the L858R mutation showed high positivity for the protein in 25/27 (93%) patients with exon 21 EGFR mutations (all with L858R) but did not identify the L861Q mutation in the remaining two patients. Conclusions: IHC with mutation-specific mAbs against EGFR is a promising method for detecting EGFR mutations in NSCLC patients. However these mAbs should be validated with additional studies to clarify their possible role in routine clinical practice for screening EGFR mutations in NSCLC patients.
Background Non-small-cell lung cancer (NSCLC) is one of the most frequent human malignancies, constituting about 80% of all lung tumors. NSCLC can be divided into genetic subsets on the basis of the activating mutations that they harbor; each of these subsets may correspond to patient cohorts that are likely to benefit from treatment with specific inhibitors [1]. Activating mutations in the epidermal growth factor receptor (EGFR), affecting hotspots within exons that code for the tyrosine kinase domain, can be found in 10-40% of NSCLC patients, mostly in adenocarcinomas, with the higher frequency observed in Asian patients [1,2]. About 50% of mutated patients harbor in-frame deletions in exon 19, (around codons 746 to 750) and 35-45% show the substitution of leucine 858 by an * Correspondence: [email protected] 1 Pangaea Biotech, USP Dexeus University Institute, Barcelona, Spain Full list of author information is available at the end of the article
arginine in the exon 21. The remaining mutants are insertions in exon 20 (5%) and uncommon substitutions spanning exons from 18 to 21, such as L861Q [3,4]. These specific mutations are related to a higher sensitivity to the tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib [4-7], whereas
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