Spatial Tumor Heterogeneity in Lung Cancer with Acquired Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Resistance: Targeting High-Level MET-Amplification and EGFR T790M Mutation Occurring at Different Sites in the Same Patient (2015)

Different mechanisms underlying acquired resistance (AR) to epidermal growth factor receptor (EGFR) inhibitors in EGFR-mutated lung cancer are known, among them the EGFRT790M mutation in approximately 50% and MET-amplifications in approximately 5% of these patients.1Sequist LV Waltman BA Dias-Santagata D et al.Genotypic and histological evolution of lung cancers acquiring resistance to EGFR inhibitors.Sci Transl Med. 2011; 3: 75ra26Crossref PubMed Scopus (2692) Google Scholar Here, we describe a patient with AR harboring both genetic aberrations at distinct tumor sites resulting in mixed response patterns following biopsy-guided sequential targeted therapy. A 55-year-old male Caucasian patient was diagnosed with lung adenocarcinoma Union for International Cancer Control stage IV (cT4cN1cM1b PUL/PLEU/OSS) in October 2011. EGFRL858R mutation was diagnosed by dideoxy sequencing. After several lines of treatment including erlotinib, cisplatin/pemetrexed, and afatinib/cetuximab, he presented in July 2013 with disease progression. Next-generation sequencing based analysis of the rebiopsy of the primary tumor (left lung upper lobe) revealed EGFRL858R and two different TP53 mutations (R110C and C277* [allele frequencies 4% vs. 26%, suggesting biclonality]), but no aberration associated with AR (Table 1; Sanger sequencing was used for validation and showed no discrepancies). Treatment was initiated with docetaxel/gemcitabine, and massive progression was diagnosed in September 2013 (lung, liver, myocard, and soft-tissue left arm; Fig. 1A). Rebiopsy of the lesion in the left arm detected EGFRL858R, TP53C277*, and high-level MET-amplification (MET/centromer7 ratio, 8.3; cutoff for high-level amplification, 2.0)2Schildhaus H Schultheis AM Ruschoff J et al.MET amplification status in therapy-naive adeno- and squamous cell carcinomas of the lung.Clin Cancer Res. 2015; 21: 907-915Crossref PubMed Scopus (126) Google Scholar in the absence of EGFRT790M. Treatment with crizotinib (2 × 250 mg/d) in combination with erlotinib (100 mg/d) was started. After 1 week of therapy, fluorodeoxyglucose (18F)-positron emission tomography–computed tomography showed a dramatic metabolic response (Fig. 1B) in the arm, the liver, and the myocardium, with improvement of the patient’s performance state. However, the primary tumor (left lung) did not respond (Fig. 1B). In December 2013, the patient presented with increasing dyspnea (Fig. 1C). Although complete metabolic response was maintained in liver and soft-tissue metastases, metabolic progression occurred in myocardial metastasis. Combination therapy was maintained. In January 2014, the patient presented with dyspnea and left pleural effusion. Analysis of pleural effusion (Fig. 1D) revealed EGFRL858R, TP53R110C, low-level MET-amplification, and EGFRT790M. The same mutations were detected in peripheral blood. Crizotinib was stopped, and the patient was enrolled into a trial evaluating a third generation EGFR-tyrosine kinase inhibitor (TKI) (NCT01802632) in February 2014. After 2 weeks, fluorodeoxyglucose (18F)-positron emission tomography–computed tomography showed control of the primary lung tumor but a strong increase in activity in the liver and myocardium (Fig. 1E). The patient was withdrawn from the trial as no concomitant antineoplastic treatment was allowed, and crizotinib treatment was restarted. Three weeks later, again a nearly complete metabolic response of the metastases presumably driven by high-level MET-amplification was observed (Fig. 1F). However, the patient suffered from recurrent pleural effusions and his performance state worsened. He finally died in April 2014.TABLE 1Biopsies Performed and Molecular FindingsDateLocalizationMethodResultsOctober 2011Lung (primarius)SangerEGFR L858RJune 2013Lung (primarius)NGS/FISH/SangerEGFR L858R, TP53 C277*, TP53 R110C, and no METampOctober 2013Muscle right armNGS/FISH/SangerEGFR L858R, TP53 C277*, and high-level METampJanuary 2014Pleural effusionNGS/FISH/SangerEGFR L858R, TP53 R110C, low-level METamp, and EGFR T790MJanuary 2014Peripheral bloodCAGEaAn NGS-based target enrichment assay detecting rearrangements, amplifications, deletions, and point mutations, in more than 300 cancer relevant genes.EGFR L858R, EGFR T790M, and TP53 R110CApril 2014Pleural effusionNGS/FISHEGFR L858R, EGFR T790M, TP53 R110C, and no METampNGS, next-generation sequencing; FISH, fluorescence in situ hybridization; Sanger, dideoxy sequencing; CAGE, Cancer genome scanner® (Blackfield AG, Cologne, Germany).a An NGS-based target enrichment assay detecting rearrangements, amplifications, deletions, and point mutations, in more than 300 cancer relevant genes. Open table in a new tab NGS, next-generation sequencing; FISH, fluorescence in situ hybridization; Sanger, dideoxy sequencing; CAGE, Cancer genome scanner® (Blackfield AG, Cologne, Germany). This report describes a patient with acquired EGFR-tyrosine kinase inhibitor resistance harboring two different resistance mechanisms, namely EGFRT790M and high-level MET-amplification, at different tumor sites. Despite rebiopsy-guided effective temporary control of the tumor clone harboring high-level MET amplification with a potent MET-inhibitor3Ou SH Kwak EL Siwak-Tapp C et al.Activity of crizotinib (PF02341066), a dual mesenchymal-epithelial transition (MET) and anaplastic lymphoma kinase (ALK) inhibitor, in a non-small cell lung cancer patient with de novo MET amplification.J Thorac Oncol. 2011; 6: 942-946Crossref PubMed Scopus (378) Google Scholar tumor activity could not be persistently controlled because of clonal heterogeneity and finally led to fatal progression of the disease (FIGURE 2, FIGURE 3). These observations not only provide a rationale for early combination therapy in AR but also point to the limitations of our current paradigmatic understanding of driver-mutation directed therapy and underlines recent analyses demonstrating genetic variability in patients with lung cancer.4Zhang J Fujimoto J Zhang J et al.Intratumor heterogeneity in localized lung adenocarcinomas delineated by multiregion sequencing.Science. 2014; 346: 256-259Crossref PubMed Scopus (697) Google Scholar,5de Bruin EC McGranahan N Mitter R et al.Spatial and temporal diversity in genomic instability processes defines lung cancer evolution.Science. 2014; 346: 251-256Crossref PubMed Scopus (779) Google ScholarFIGURE 3Liquid biopsy reveals epidermal growth factor receptor (EGFR) and TP53 mutations: results of the peripheral blood analysis (January 2014). A, EGFRL858R mutation with an allele frequency of 13%. B, EGFRT790M mutation with an allele frequency of 10%. C, TP53R110C mutation with an allele frequency of 9%. All identified and illustrated by integrative genome viewer.View Large Image Figure ViewerDownload (PPT)