Contribution of <i>KRAS</i> mutations and c.2369C &gt; T (p.T790M) <i>EGFR</i> to acquired resistance to EGFR-TKIs in <i>EGFR</i> mutant NSCLC: a study on circulating tumor DNA

Abstract

// Marzia Del Re 1 , Marcello Tiseo 2 , Paola Bordi 2 , Armida D&rsquo;Incecco 3 , Andrea Camerini 4 , Iacopo Petrini 5 , Maurizio Lucchesi 6 , Alessandro Inno 7 , Daniele Spada 8 , Enrico Vasile 6 , Valentina Citi 1 , Giorgio Malpeli 9 , Enrica Testa 8 , Stefania Gori 7 , Alfredo Falcone 6 , Domenico Amoroso 4 , Antonio Chella 10 , Federico Cappuzzo 3 , Andrea Ardizzoni 2 , Aldo Scarpa 9 , Romano Danesi 1 1 Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy 2 Medical Oncology Unit, Azienda Ospedaliero-Universitaria, Parma, Italy 3 Medical Oncology Unit, AUSL6, Istituto Toscano Tumori, Livorno, Italy 4 Medical Oncology Unit, AUSL12, Istituto Toscano Tumori, Lido di Camaiore, Italy 5 Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy 6 Medical Oncology Unit 2, Azienda Ospedaliero-Universitaria, Pisa, Italy 7 Medical Oncology Unit, Ospedale Sacro Cuore, Negrar, Italy 8 Medical Oncolgy Unit, Ospedale Santa Maria della Misericordia, Urbino, Italy 9 ARC-NET Research Centre and Department of Pathology and Diagnostics, Azienda Ospedaliero-Universitaria, Verona, Italy 10 Lung Diseases Unit, Azienda Ospedaliero-Universitaria, Pisa, Italy Correspondence to: Romano Danesi, email: romano.danesi@unipi.it Keywords: cell-free circulating tumor DNA, KRAS, EGFR, activating mutation, tyrosine kinase inhibitors Received: June 24, 2015&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Accepted: December 29, 2015&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Published: January 20, 2016 ABSTRACT Introduction: KRAS oncogene mutations ( MUT KRAS ) drive resistance to EGFR inhibition by providing alternative signaling as demonstrated in colo-rectal cancer. In non-small cell lung cancer (NSCLC), the efficacy of treatment with EGFR tyrosine kinase inhibitors (EGFR-TKIs) depends on activating EGFR mutations ( MUT EGFR ). However, inhibition of EGFR may select resistant cells displaying alternative signaling, i.e., KRAS , or restoration of EGFR activity due to additional MUT EGFR , i.e., the c.2369C &gt; T ( p.T790M EGFR ). Aim: The aim of this study was to investigate the appearance of MUT KRAS during EGFR-TKI treatment and their contribution to drug resistance. Methods: This study used cell-free circulating tumor DNA (cftDNA) to evaluate the appearance of codon 12 MUT KRAS and p.T790M EGFR mutations in 33 advanced NSCLC patients progressing after an EGFR-TKI. Results: p.T790M EGFR was detected in 11 (33.3%) patients, MUT KRAS at codon 12 in 3 (9.1%) while both p.T790M EGFR and MUT KRAS codon 12 were found in 13 (39.4%) patients. Six patients (18.2%) were KRAS wild-type ( WT KRAS ) and negative for p.T790M EGFR . In 8 subjects paired tumor re-biopsy/plasma samples were available; the percent concordance of tissue/plasma was 62.5% for p.T790M EGFR and 37.5% for MUT KRAS . The analysis of time to progression (TTP) and overall survival (OS) in WT KRAS vs. MUT KRAS were not statistically different, even if there was a better survival with WT KRAS vs. MUT KRAS , i.e., TTP 14.4 vs. 11.4 months ( p = 0.97) and OS 40.2 vs. 35.0 months ( p = 0.56), respectively. Conclusions: MUT KRAS could be an additional mechanism of escape from EGFR-TKI inhibition and cftDNA is a feasible approach to monitor the molecular development of drug resistance.