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2.  Primary Lung Adenocarcinomas in Children and Adolescents Treated for Pediatric Malignancies 
Introduction
Primary lung adenocarcinoma is extremely rare in the pediatric age group. There have been anecdotal reports of lesions that are histologically indistinguishable from adult-type pulmonary adenocarcinoma in young patients after treatment for nonpulmonary cancers. Herein, we present clinical, histopathologic, and molecular data on eight such cases.
Methods
Histopathologic evaluation of the tumors was performed according to the World Health Organization classification. Molecular studies for EGFR and KRAS mutations were performed on six patients with sufficient material.
Results
All eight patients were never smokers, four males and four females. Median age at nonpulmonary cancer diagnosis was 14 years (range, 3–23 years). Pulmonary adenocarcinomas were diagnosed at a median age of 15 years (range, 10–24 years); tumors were 0.1 to 2.0 cm in size and in some cases coexisted with metastases from the original cancer. Retrospective review showed that in at least three patients, the nodules were radiographically present before chemotherapy. Of six patients whose tumors were tested for common EGFR and KRAS mutations, two were positive for the former and one for the latter. At a median follow-up of 11 months (range, 2–29 months), six patients remained well without lung nodules and two had additional small, peripheral lung nodules that have not been biopsied.
Conclusions
Pulmonary lesions found in young patients with pediatric cancers can be histologically indistinguishable from lung adenocarcinoma seen in adults, may display typical adenocarcinoma-associated mutations of EGFR and KRAS, and may precede the administration of cytotoxic chemotherapy.
doi:10.1097/JTO.0b013e3181f69f08
PMCID: PMC4243865  PMID: 20975376
Bronchioloalveolar carcinoma; Lung cancer; Adenocarcinoma; Secondary malignancies; Osteosarcoma; EGFR; KRAS
3.  Using Multiplexed Assays of Oncogenic Drivers in Lung Cancers to Select Targeted Drugs 
IMPORTANCE
Targeting oncogenic drivers (genomic alterations critical to cancer development and maintenance) has transformed the care of patients with lung adenocarcinomas. The Lung Cancer Mutation Consortium was formed to perform multiplexed assays testing adenocarcinomas of the lung for drivers in 10 genes to enable clinicians to select targeted treatments and enroll patients into clinical trials.
OBJECTIVES
To determine the frequency of oncogenic drivers in patients with lung adenocarcinomas and to use the data to select treatments targeting the identified driver(s) and measure survival.
DESIGN, SETTING, AND PARTICIPANTS
From 2009 through 2012, 14 sites in the United States enrolled patients with metastatic lung adenocarcinomas and a performance status of 0 through 2 and tested their tumors for 10 drivers. Information was collected on patients, therapies, and survival.
INTERVENTIONS
Tumors were tested for 10 oncogenic drivers, and results were used to select matched targeted therapies.
MAIN OUTCOMES AND MEASURES
Determination of the frequency of oncogenic drivers, the proportion of patients treated with genotype-directed therapy, and survival.
RESULTS
From 2009 through 2012, tumors from 1007 patients were tested for at least 1 gene and 733 for 10 genes (patients with full genotyping). An oncogenic driver was found in 466 of 733 patients (64%). Among these 733 tumors, 182 tumors (25%) had the KRAS driver; sensitizing EGFR, 122 (17%); ALK rearrangements, 57 (8%); other EGFR, 29 (4%); 2 or more genes, 24 (3%); ERBB2 (formerly HER2), 19 (3%); BRAF, 16 (2%); PIK3CA, 6 (<1%); MET amplification, 5 (<1%); NRAS, 5 (<1%); MEK1, 1 (<1%); AKT1, 0. Results were used to select a targeted therapy or trial in 275 of 1007 patients (28%). The median survival was 3.5 years (interquartile range [IQR], 1.96-7.70) for the 260 patients with an oncogenic driver and genotype-directed therapy compared with 2.4 years (IQR, 0.88-6.20) for the 318 patients with any oncogenic driver(s) who did not receive genotype-directed therapy (propensity score–adjusted hazard ratio, 0.69 [95% CI, 0.53-0.9], P = .006).
CONCLUSIONS AND RELEVANCE
Actionable drivers were detected in 64% of lung adenocarcinomas. Multiplexed testing aided physicians in selecting therapies. Although individuals with drivers receiving a matched targeted agent lived longer, randomized trials are required to determine if targeting therapy based on oncogenic drivers improves survival.
doi:10.1001/jama.2014.3741
PMCID: PMC4163053  PMID: 24846037
4.  Identification of KIF5B-RET and GOPC-ROS1 fusions in lung adenocarcinomas through a comprehensive mRNA-based screen for tyrosine kinase fusions 
Background
The mutually exclusive pattern of the major driver oncogenes in lung cancer suggests that other mutually exclusive oncogenes exist. We performed a systematic search for tyrosine kinase (TK) fusions by screening all TKs for aberrantly high RNA expression levels of the 3′ kinase domain (KD) exons relative to more 5′ exons.
Methods
We studied 69 patients (including 5 never smokers and 64 current or former smokers) with lung adenocarcinoma negative for all major mutations in KRAS, EGFR, BRAF, MEK1, and HER2, and for ALK fusions (termed “pan-negative”). A NanoString-based assay was designed to query the transcripts of 90 TKs at two points: 5′ to the KD and within the KD or 3′ to it. Tumor RNAs were hybridized to the NanoString probes and analyzed for outlier 3′ to 5′ expression ratios. Presumed novel fusion events were studied by rapid amplification of cDNA ends (RACE) and confirmatory RT-PCR and FISH.
Results
We identified 1 case each of aberrant 3′ to 5′ ratios in ROS1 and RET. RACE isolated a GOPC-ROS1 (FIG-ROS1) fusion in the former and a KIF5B-RET fusion in the latter, both confirmed by RT-PCR. The RET rearrangement was also confirmed by FISH. The KIF5B-RET patient was one of only 5 never smokers in this cohort.
Conclusion
The KIF5B-RET fusion defines an additional subset of lung cancer with a potentially targetable driver oncogene enriched in never smokers with “pan-negative” lung adenocarcinomas. We also report for the first time in lung cancer the GOPC-ROS1 fusion previously characterized in glioma.
doi:10.1158/1078-0432.CCR-12-0838
PMCID: PMC4234119  PMID: 23052255
lung cancer; kinase; gene fusion; RET; ROS1; ALK
5.  A recurrent neomorphic mutation in MYOD1 defines a clinically aggressive subset of embryonal rhabdomyosarcoma associated with PI3K/AKT pathway mutations 
Nature genetics  2014;46(6):595-600.
Rhabdomyosarcoma (RMS), a cancer of skeletal muscle lineage, is the most common soft-tissue sarcoma in children [1]. Major subtypes of RMS include alveolar (ARMS) and embryonal (ERMS).[2, 3] Whereas ARMS typically contain translocations generating the PAX3-FOXO1 or PAX7-FOXO1 aberrant transcription factors which block terminal myogenic differentiation [4-6], no functionally comparable genetic event has been found in ERMS. Here, we report the discovery, through whole exome sequencing, of a recurrent somatic point mutation Leu122Arg in the myogenic transcription factor, MYOD1, in a distinctive subset of ERMS with poor outcomes that also often contain PI3K/AKT pathway mutations. Previous mutagenesis studies had shown that MYOD1 Leu122Arg can block wild-type MYOD1 function and bind to MYC consensus sequences [7], suggesting a possible switch from differentiation to proliferation. Our functional data now confirm this prediction. RMS with MYOD1 Leu122Arg represents a molecularly defined subset of RMS eligible for high risk protocols and targeted therapeutic development.
doi:10.1038/ng.2969
PMCID: PMC4231202  PMID: 24793135
6.  Reduced NF1 expression confers resistance to EGFR inhibition in lung cancer 
Cancer discovery  2014;4(5):606-619.
SUMMARY
Activating mutations in the EGF receptor (EGFR) are associated with clinical responsiveness to EGFR tyrosine kinase inhibitors (TKIs), such as erlotinib and gefitinib. However, resistance eventually arises, often due to a second EGFR mutation, most commonly T790M. Through a genome-wide siRNA screen in a human lung cancer cell line and analyses of murine mutant EGFR-driven lung adenocarcinomas, we found that erlotinib resistance was associated with reduced expression of neurofibromin, the RAS GTPase activating protein encoded by the NF1 gene. Erlotinib failed to fully inhibit RAS-ERK signaling when neurofibromin levels were reduced. Treatment of neurofibromin-deficient lung cancers with a MEK inhibitor restored sensitivity to erlotinib. Low levels of NF1 expression were associated with primary and acquired resistance of lung adenocarcinomas to EGFR TKIs in patients. These findings identify a subgroup of patients with EGFR mutant lung adenocarcinoma who might benefit from combination therapy with EGFR and MEK inhibitors.
doi:10.1158/2159-8290.CD-13-0741
PMCID: PMC4011693  PMID: 24535670
NF1; EGFR; KRAS; MAPK pathway; drug resistance; erlotinib; gefitinib; lung adenocarcinoma
7.  Reduced NF1 expression confers resistance to EGFR inhibition in lung cancer 
Cancer discovery  2014;4(5):606-619.
SUMMARY
Activating mutations in the EGF receptor (EGFR) are associated with clinical responsiveness to EGFR tyrosine kinase inhibitors (TKIs), such as erlotinib and gefitinib. However, resistance eventually arises, often due to a second EGFR mutation, most commonly T790M. Through a genome-wide siRNA screen in a human lung cancer cell line and analyses of murine mutant EGFR-driven lung adenocarcinomas, we found that erlotinib resistance was associated with reduced expression of neurofibromin, the RAS GTPase activating protein encoded by the NF1 gene. Erlotinib failed to fully inhibit RAS-ERK signaling when neurofibromin levels were reduced. Treatment of neurofibromin-deficient lung cancers with a MEK inhibitor restored sensitivity to erlotinib. Low levels of NF1 expression were associated with primary and acquired resistance of lung adenocarcinomas to EGFR TKIs in patients. These findings identify a subgroup of patients with EGFR mutant lung adenocarcinoma who might benefit from combination therapy with EGFR and MEK inhibitors.
doi:10.1158/2159-8290.CD-13-0741
PMCID: PMC4011693  PMID: 24535670
NF1; EGFR; KRAS; MAPK pathway; drug resistance; erlotinib; gefitinib; lung adenocarcinoma
8.  Comprehensive molecular characterization of gastric adenocarcinoma 
Bass, Adam J. | Thorsson, Vesteinn | Shmulevich, Ilya | Reynolds, Sheila M. | Miller, Michael | Bernard, Brady | Hinoue, Toshinori | Laird, Peter W. | Curtis, Christina | Shen, Hui | Weisenberger, Daniel J. | Schultz, Nikolaus | Shen, Ronglai | Weinhold, Nils | Kelsen, David P. | Bowlby, Reanne | Chu, Andy | Kasaian, Katayoon | Mungall, Andrew J. | Robertson, A. Gordon | Sipahimalani, Payal | Cherniack, Andrew | Getz, Gad | Liu, Yingchun | Noble, Michael S. | Pedamallu, Chandra | Sougnez, Carrie | Taylor-Weiner, Amaro | Akbani, Rehan | Lee, Ju-Seog | Liu, Wenbin | Mills, Gordon B. | Yang, Da | Zhang, Wei | Pantazi, Angeliki | Parfenov, Michael | Gulley, Margaret | Piazuelo, M. Blanca | Schneider, Barbara G. | Kim, Jihun | Boussioutas, Alex | Sheth, Margi | Demchok, John A. | Rabkin, Charles S. | Willis, Joseph E. | Ng, Sam | Garman, Katherine | Beer, David G. | Pennathur, Arjun | Raphael, Benjamin J. | Wu, Hsin-Ta | Odze, Robert | Kim, Hark K. | Bowen, Jay | Leraas, Kristen M. | Lichtenberg, Tara M. | Weaver, Stephanie | McLellan, Michael | Wiznerowicz, Maciej | Sakai, Ryo | Getz, Gad | Sougnez, Carrie | Lawrence, Michael S. | Cibulskis, Kristian | Lichtenstein, Lee | Fisher, Sheila | Gabriel, Stacey B. | Lander, Eric S. | Ding, Li | Niu, Beifang | Ally, Adrian | Balasundaram, Miruna | Birol, Inanc | Bowlby, Reanne | Brooks, Denise | Butterfield, Yaron S. N. | Carlsen, Rebecca | Chu, Andy | Chu, Justin | Chuah, Eric | Chun, Hye-Jung E. | Clarke, Amanda | Dhalla, Noreen | Guin, Ranabir | Holt, Robert A. | Jones, Steven J.M. | Kasaian, Katayoon | Lee, Darlene | Li, Haiyan A. | Lim, Emilia | Ma, Yussanne | Marra, Marco A. | Mayo, Michael | Moore, Richard A. | Mungall, Andrew J. | Mungall, Karen L. | Nip, Ka Ming | Robertson, A. Gordon | Schein, Jacqueline E. | Sipahimalani, Payal | Tam, Angela | Thiessen, Nina | Beroukhim, Rameen | Carter, Scott L. | Cherniack, Andrew D. | Cho, Juok | Cibulskis, Kristian | DiCara, Daniel | Frazer, Scott | Fisher, Sheila | Gabriel, Stacey B. | Gehlenborg, Nils | Heiman, David I. | Jung, Joonil | Kim, Jaegil | Lander, Eric S. | Lawrence, Michael S. | Lichtenstein, Lee | Lin, Pei | Meyerson, Matthew | Ojesina, Akinyemi I. | Pedamallu, Chandra Sekhar | Saksena, Gordon | Schumacher, Steven E. | Sougnez, Carrie | Stojanov, Petar | Tabak, Barbara | Taylor-Weiner, Amaro | Voet, Doug | Rosenberg, Mara | Zack, Travis I. | Zhang, Hailei | Zou, Lihua | Protopopov, Alexei | Santoso, Netty | Parfenov, Michael | Lee, Semin | Zhang, Jianhua | Mahadeshwar, Harshad S. | Tang, Jiabin | Ren, Xiaojia | Seth, Sahil | Yang, Lixing | Xu, Andrew W. | Song, Xingzhi | Pantazi, Angeliki | Xi, Ruibin | Bristow, Christopher A. | Hadjipanayis, Angela | Seidman, Jonathan | Chin, Lynda | Park, Peter J. | Kucherlapati, Raju | Akbani, Rehan | Ling, Shiyun | Liu, Wenbin | Rao, Arvind | Weinstein, John N. | Kim, Sang-Bae | Lee, Ju-Seog | Lu, Yiling | Mills, Gordon | Laird, Peter W. | Hinoue, Toshinori | Weisenberger, Daniel J. | Bootwalla, Moiz S. | Lai, Phillip H. | Shen, Hui | Triche, Timothy | Van Den Berg, David J. | Baylin, Stephen B. | Herman, James G. | Getz, Gad | Chin, Lynda | Liu, Yingchun | Murray, Bradley A. | Noble, Michael S. | Askoy, B. Arman | Ciriello, Giovanni | Dresdner, Gideon | Gao, Jianjiong | Gross, Benjamin | Jacobsen, Anders | Lee, William | Ramirez, Ricardo | Sander, Chris | Schultz, Nikolaus | Senbabaoglu, Yasin | Sinha, Rileen | Sumer, S. Onur | Sun, Yichao | Weinhold, Nils | Thorsson, Vésteinn | Bernard, Brady | Iype, Lisa | Kramer, Roger W. | Kreisberg, Richard | Miller, Michael | Reynolds, Sheila M. | Rovira, Hector | Tasman, Natalie | Shmulevich, Ilya | Ng, Santa Cruz Sam | Haussler, David | Stuart, Josh M. | Akbani, Rehan | Ling, Shiyun | Liu, Wenbin | Rao, Arvind | Weinstein, John N. | Verhaak, Roeland G.W. | Mills, Gordon B. | Leiserson, Mark D. M. | Raphael, Benjamin J. | Wu, Hsin-Ta | Taylor, Barry S. | Black, Aaron D. | Bowen, Jay | Carney, Julie Ann | Gastier-Foster, Julie M. | Helsel, Carmen | Leraas, Kristen M. | Lichtenberg, Tara M. | McAllister, Cynthia | Ramirez, Nilsa C. | Tabler, Teresa R. | Wise, Lisa | Zmuda, Erik | Penny, Robert | Crain, Daniel | Gardner, Johanna | Lau, Kevin | Curely, Erin | Mallery, David | Morris, Scott | Paulauskis, Joseph | Shelton, Troy | Shelton, Candace | Sherman, Mark | Benz, Christopher | Lee, Jae-Hyuk | Fedosenko, Konstantin | Manikhas, Georgy | Potapova, Olga | Voronina, Olga | Belyaev, Smitry | Dolzhansky, Oleg | Rathmell, W. Kimryn | Brzezinski, Jakub | Ibbs, Matthew | Korski, Konstanty | Kycler, Witold | ŁaŸniak, Radoslaw | Leporowska, Ewa | Mackiewicz, Andrzej | Murawa, Dawid | Murawa, Pawel | Spychała, Arkadiusz | Suchorska, Wiktoria M. | Tatka, Honorata | Teresiak, Marek | Wiznerowicz, Maciej | Abdel-Misih, Raafat | Bennett, Joseph | Brown, Jennifer | Iacocca, Mary | Rabeno, Brenda | Kwon, Sun-Young | Penny, Robert | Gardner, Johanna | Kemkes, Ariane | Mallery, David | Morris, Scott | Shelton, Troy | Shelton, Candace | Curley, Erin | Alexopoulou, Iakovina | Engel, Jay | Bartlett, John | Albert, Monique | Park, Do-Youn | Dhir, Rajiv | Luketich, James | Landreneau, Rodney | Janjigian, Yelena Y. | Kelsen, David P. | Cho, Eunjung | Ladanyi, Marc | Tang, Laura | McCall, Shannon J. | Park, Young S. | Cheong, Jae-Ho | Ajani, Jaffer | Camargo, M. Constanza | Alonso, Shelley | Ayala, Brenda | Jensen, Mark A. | Pihl, Todd | Raman, Rohini | Walton, Jessica | Wan, Yunhu | Demchok, John A. | Eley, Greg | Mills Shaw, Kenna R. | Sheth, Margi | Tarnuzzer, Roy | Wang, Zhining | Yang, Liming | Zenklusen, Jean Claude | Davidsen, Tanja | Hutter, Carolyn M. | Sofia, Heidi J. | Burton, Robert | Chudamani, Sudha | Liu, Jia
Nature  2014;513(7517):202-209.
Gastric cancer is a leading cause of cancer deaths, but analysis of its molecular and clinical characteristics has been complicated by histological and aetiological heterogeneity. Here we describe a comprehensive molecular evaluation of 295 primary gastric adenocarcinomas as part of The Cancer Genome Atlas (TCGA) project. We propose a molecular classification dividing gastric cancer into four subtypes: tumours positive for Epstein–Barr virus, which display recurrent PIK3CA mutations, extreme DNA hypermethylation, and amplification of JAK2, CD274 (also known as PD-L1) and PDCD1LG2 (also knownasPD-L2); microsatellite unstable tumours, which show elevated mutation rates, including mutations of genes encoding targetable oncogenic signalling proteins; genomically stable tumours, which are enriched for the diffuse histological variant and mutations of RHOA or fusions involving RHO-family GTPase-activating proteins; and tumours with chromosomal instability, which show marked aneuploidy and focal amplification of receptor tyrosine kinases. Identification of these subtypes provides a roadmap for patient stratification and trials of targeted therapies.
doi:10.1038/nature13480
PMCID: PMC4170219  PMID: 25079317
9.  Molecular Testing Guideline for Selection of Lung Cancer Patients for EGFR and ALK Tyrosine Kinase Inhibitors 
Objective
To establish evidence-based recommendations for the molecular analysis of lung cancers that are required to guide EGFR- and ALK-directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed.
Participants
Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies.
Evidence
Three unbiased literature searches of electronic databases were performed to capture articles published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation.
Consensus Process
Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4).
Conclusions
The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.
doi:10.5858/arpa.2012-0720-OA
PMCID: PMC4162344  PMID: 23551194
10.  Immunohistochemical staining with EGFR mutation-specific antibodies: high specificity as a diagnostic marker for lung adenocarcinoma 
We previously demonstrated a high specificity of immunohistochemistry using epidermal growth factor receptor (EGFR) mutation-specific antibodies in lung adenocarcinoma and correlation with EGFR mutation analysis. In this study, we assessed EGFR mutation status by immunohistochemistry in a variety of extrapulmonary malignancies, especially those that frequently show EGFR overexpression. Tissue microarrays containing triplicate cores of breast carcinomas (n = 300), colorectal carcinomas (n = 65), pancreatic adenocarcinoma (n = 145), and uterine carcinosarcoma or malignant mixed müllerian tumors (n = 25) were included in the study. Tissue microarray of lung adenocarcinoma with known EGFR mutation status was used as reference. Immunohistochemistry was performed using antibodies specific for the E746-A750del and L858R mutations. In pulmonary adenocarcinoma, a staining intensity of 2+ or 3+ correlates with mutation status and is therefore considered as positive. Out of 300 breast carcinomas, 293 (98%) scored 0, 5 (2%) had 1+ staining, 2 (1%) were 2+ for the L858R antibody. All breast carcinomas scored 0 with the E746-A750 antibody. All the colorectal, pancreatic carcinomas and malignant mixed müllerian tumors were negative (0) for both antibodies. Molecular analysis of the breast carcinomas that scored 2+ for L858R showed no mutation. Our results show that EGFR mutation-specific antibodies could be an additional tool distinguishing primary versus metastatic carcinomas in the lung. False-positivity can be seen in breast carcinoma but is extremely rare (1%).
doi:10.1038/modpathol.2013.53
PMCID: PMC4159955  PMID: 23599147
epidermal growth factor receptor; immunohistochemistry; mutation-specific antibody; triple-negative; breast cancer
11.  Response to Cabozantinib in Patients with RET Fusion-Positive Lung Adenocarcinomas 
Cancer discovery  2013;3(6):630-635.
The discovery of RET fusions in lung cancers has uncovered a new therapeutic target for patients whose tumors harbor these changes. In an unselected population of non–small cell lung carcinomas (NSCLCs), RET fusions are present in 1% to 2% of cases. This incidence increases substantially, however, in never-smokers with lung adenocarcinomas that lack other known driver oncogenes. Although preclinical data provide experimental support for the use of RET inhibitors in the treatment of RET fusion-positive tumors, clinical data on response are lacking. We report preliminary data for the first three patients treated with the RET inhibitor cabozantinib on a prospective phase II trial for patients with RET fusion-positive NSCLCs (NCT01639508). Confirmed partial responses were observed in 2 patients, including one harboring a novel TRIM33–RET fusion. A third patient with a KIF5B–RET fusion has had prolonged stable disease approaching 8 months (31 weeks). All three patients remain progression-free on treatment.
doi:10.1158/2159-8290.CD-13-0035
PMCID: PMC4160032  PMID: 23533264
12.  Molecular Testing Guideline for Selection of Lung Cancer Patients for EGFR and ALK Tyrosine Kinase Inhibitors 
Objective
To establish evidence-based recommendations for the molecular analysis of lung cancers that are that are required to guide EGFR- and ALK-directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed.
Participants
Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies.
Evidence
Three unbiased literature searches of electronic databases were performed to capture articles published published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation.
Consensus Process
Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4).
Conclusions
The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.
doi:10.1097/JTO.0b013e318290868f
PMCID: PMC4159960  PMID: 23552377
13.  Combining integrated genomics and functional genomics to dissect the biology of a cancer-associated, aberrant transcription factor, the ASPSCR1–TFE3 fusion oncoprotein‡ 
The Journal of pathology  2013;229(5):743-754.
Oncogenic rearrangements of the TFE3 transcription factor gene are found in two distinct human cancers. These include ASPSCR1–TFE3 in all cases of alveolar soft part sarcoma (ASPS) and ASPSCR1–TFE3, PRCC-TFE3, SFPQ-TFE3 and others in a subset of paediatric and adult RCCs. Here we examined the functional properties of the ASPSCR1–TFE3 fusion oncoprotein, defined its target promoters on a genome-wide basis and performed a high-throughput RNA interference screen to identify which of its transcriptional targets contribute to cancer cell proliferation. We first confirmed that ASPSCR1–TFE3 has a predominantly nuclear localization and functions as a stronger transactivator than native TFE3. Genome-wide location analysis performed on the FU-UR-1 cell line, which expresses endogenous ASPSCR1–TFE3, identified 2193 genes bound by ASPSCR1–TFE3. Integration of these data with expression profiles of ASPS tumour samples and inducible cell lines expressing ASPSCR1–TFE3 defined a subset of 332 genes as putative up-regulated direct targets of ASPSCR1–TFE3, including MET (a previously known target gene) and 64 genes as down-regulated targets of ASPSCR1–TFE3. As validation of this approach to identify genuine ASPSCR1–TFE3 target genes, two up-regulated genes bound by ASPSCR1–TFE3, CYP17A1 and UPP1, were shown by multiple lines of evidence to be direct, endogenous targets of transactivation by ASPSCR1–TFE3. As the results indicated that ASPSCR1–TFE3 functions predominantly as a strong transcriptional activator, we hypothesized that a subset of its up-regulated direct targets mediate its oncogenic properties. We therefore chose 130 of these up-regulated direct target genes to study in high-throughput RNAi screens, using FU-UR-1 cells. In addition to MET, we provide evidence that 11 other ASPSCR1–TFE3 target genes contribute to the growth of ASPSCR1–TFE3-positive cells. Our data suggest new therapeutic possibilities for cancers driven by TFE3 fusions. More generally, this work establishes a combined integrated genomics/functional genomics strategy to dissect the biology of oncogenic, chimeric transcription factors.
doi:10.1002/path.4158
PMCID: PMC4083568  PMID: 23288701
ASPSCR1; TFE3; CYP17A1; uridine phosphorylase; NAMPT; alveolar soft part sarcoma; renal carcinoma; chromosomal translocation
14.  Morphologic Features of Adenocarcinoma of the Lung Predictive of Response to the Epidermal Growth Factor Receptor Kinase Inhibitors Erlotinib and Gefitinib 
Context
A subset of lung adenocarcinomas appears preferentially sensitive to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). EGFR-activating mutations and never smoking are associated with response to TKIs.
Objectives
To describe the morphology of adenocarcinomas responsive to TKIs, compare it to tumors in nonresponding patients, and correlate findings with EGFR mutations, gene copy number, and protein expression.
Design
Material from 52 EGFR TKI-treated patients was studied: 29 responders and 23 nonresponders. Adenocarcinoma subtypes and morphologic features were defined in histologic and cytologic material. EGFR mutations were detected by sequencing, copy number by chromogenic in situ hybridization, and expression by immunohistochemistry.
Results
Tumors from TKI responders tended to be better-differentiated adenocarcinomas with bronchioloalveolar carcinoma components. Nonresponders showed more heterogeneous morphology, higher grade, and more subtypes, and were more likely to show solid growth. In nonresponders, the only pure bronchioloalveolar carcinoma was mucinous, a subtype known to be negative for EGFR mutations. Using World Health Organization criteria, all tumors in both groups other than pure bronchioloalveolar carcinomas would be classified as adenocarcinomas, mixed subtype, thereby obscuring some of these distinctions. EGFR mutations were significantly more common in responders (22/29 vs 0/23; P < .001). Immunohistochemistry and chromogenic in situ hybridization results were not significantly correlated with EGFR mutations or response to TKIs in this study.
Conclusions
Overall, histologic differences exist between tumors that respond to TKIs and those that do not, although sampling affects classification, and there is significant histologic overlap between the 2 groups. Response is strongly associated with EGFR mutations.
doi:10.1043/1543-2165-133.3.470
PMCID: PMC4016915  PMID: 19260752
15.  Somatic mutations of the Parkinson's disease–associated gene PARK2 in glioblastoma and other human malignancies 
Nature genetics  2009;42(1):77-82.
Mutation of the gene PARK2, which encodes an E3 ubiquitin ligase, is the most common cause of early-onset Parkinson's disease1, 2, 3. In a search for multisite tumor suppressors, we identified PARK2 as a frequently targeted gene on chromosome 6q25.2–q27 in cancer. Here we describe inactivating somatic mutations and frequent intragenic deletions of PARK2 in human malignancies. The PARK2 mutations in cancer occur in the same domains, and sometimes at the same residues, as the germline mutations causing familial Parkinson's disease. Cancer-specific mutations abrogate the growth-suppressive effects of the PARK2 protein. PARK2 mutations in cancer decrease PARK2's E3 ligase activity, compromising its ability to ubiquitinate cyclin E and resulting in mitotic instability. These data strongly point to PARK2 as a tumor suppressor on 6q25.2–q27. Thus, PARK2, a gene that causes neuronal dysfunction when mutated in the germline, may instead contribute to oncogenesis when altered in non-neuronal somatic cells.
doi:10.1038/ng.491
PMCID: PMC4002225  PMID: 19946270
16.  Analysis of Tumor Specimens at the Time of Acquired Resistance to EGFR TKI therapy in 155 patients with EGFR mutant Lung Cancers 
Purpose
All patients with EGFR mutant lung cancers eventually develop acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). Smaller series have identified various mechanisms of resistance, but systematic evaluation of a large number of patients to definitively establish the frequency of various mechanisms has not been performed.
Experimental Design
Patients with lung adenocarcinomas and acquired resistance to erlotinib or gefitinib enrolled onto a prospective biopsy protocol and underwent a re-biopsy after the development of acquired resistance. Histology was reviewed. Samples underwent genotyping for mutations in EGFR, AKT1, BRAF, ERBB2, KRAS, MEK1, NRAS and PIK3CA, and FISH for MET and HER2.
Results
Adequate tumor samples for molecular analysis were obtained in 155 patients. Ninety-eight had second-site EGFR T790M mutations (63%, 95% CI 55-70%) and four had small cell transformation (3%, 95% CI 0-6%). MET amplification was seen in 4/75 (5%, 95% CI 1-13%). HER2 amplification was seen in 3/24 (13%, 95% CI 3-32%). We did not detect any acquired mutations in PIK3CA, AKT1, BRAF, ERBB2, KRAS, MEK1, or NRAS. (0/88, 0%, 95% CI 0-4%). Overlap among mechanisms of acquired resistance was seen in 4%.
Conclusions
This is the largest series reporting mechanisms of acquired resistance to EGFR TKI therapy. We identified EGFR T790M as the most common mechanism of acquired resistance, while MET amplification, HER2 amplification, and small cell histologic transformation occur less frequently. More comprehensive methods to characterize molecular alterations in this setting are needed to improve our understanding of acquired resistance to EGFR TKIs.
doi:10.1158/1078-0432.CCR-12-2246
PMCID: PMC3630270  PMID: 23470965
EGFR mutant lung cancer; lung adenocarcinoma; targeted therapy; acquired resistance; tyrosine kinase inhibitor therapy
17.  KRAS mutations are associated with solid growth pattern and tumor-infiltrating leukocytes in lung adenocarcinoma 
KRAS mutations define a clinically-distinct subgroup of lung adenocarcinoma patients, characterized by smoking history, resistance to EGFR-targeted therapies, and adverse prognosis. Whether KRAS- mutated lung adenocarcinomas also have distinct histopathologic features is not well established. We tested 180 resected lung adenocarcinomas for KRAS and EGFR mutations by high-sensitivity mass spectrometry-based genotyping (Sequenom) and PCR-based sizing assays. All tumors were assessed for the proportion of standard histologic patterns (lepidic, acinar, papillary, micropapillary, solid and mucinous), several other histologic and clinical parameters, and TTF-1 expression by immunohistochemistry. Among 180 carcinomas, 63 (35%) had KRAS mutations (KRAS+), 35 (19%) had EGFR mutations (EGFR+), and 82 (46%) had neither mutation (KRAS-/EGFR-). Solid growth pattern was significantly over-represented in KRAS+ carcinomas: the mean ± standard deviation for the amount of solid pattern in KRAS+ carcinomas was 27 ± 34% compared to 3 ± 10% in EGFR+ (P<0.001) and 15 ± 27% in KRAS-/EGFR- (P=0.033) tumors. Furthermore, at least focal (>20%) solid component was more common in KRAS+ (28/63; 44%) compared to EGFR+ (2/35; 6%; P<0.001) and KRAS-/EGFR- (21/82; 26%; P=0.012) carcinomas. KRAS mutations were also over-represented in mucinous carcinomas, and were significantly associated with the presence of tumor-infiltrating leukocytes and heavier smoking history. EGFR mutations were associated with non-mucinous non-solid patterns, particularly lepidic and papillary, lack of necrosis, lack of cytologic atypia, hobnail cytology, TTF-1 expression, and never/light smoking history. In conclusion, extended molecular and clinicopathologic analysis of lung adenocarcinomas reveals a novel association of KRAS mutations with solid histology and tumor-infiltrating inflammatory cells, and expands on several previously recognized morphologic and clinical associations of KRAS and EGFR mutations. Solid growth pattern was recently shown to be a strong predictor of aggressive behavior in lung adenocarcinomas, which may underlie the unfavorable prognosis associated with KRAS mutations in these tumors.
doi:10.1038/modpathol.2013.74
PMCID: PMC3732528  PMID: 23619604
KRAS; EGFR; lung; adenocarcinoma; TTF-1
18.  Association of KRAS and EGFR Mutations with Survival in Patients with Advanced Lung Adenocarcinomas 
Cancer  2012;119(2):356-362.
Background
Lung adenocarcinomas can be distinguished by identifying mutated driver oncogenes including EGFR and KRAS. Mutations in EGFR are associated with both an improved survival as well as response to treatment with erlotinib and gefitinib. However, the prognostic significance of KRAS has not been evaluated in large numbers of patients and remains controversial. We examined the association of EGFR and KRAS mutations with survival among patients with advanced lung adenocarcinomas.
Methods
We analyzed data from patients with advanced lung adenocarcinomas and known EGFR and KRAS mutation status evaluated between 2002 and 2009. We collected clinical variables including age, gender, Karnofsky Performance Status, smoking history, and treatment history. Overall survival from diagnosis of advanced disease was analyzed using Kaplan-Meier and Cox proportional hazard methods.
Results
We evaluated 1036 patients, including 610 women (59%) and 344 never-smokers (33%). Patients had a median age of 65 (range, 25–92) and the majority (81%) had a KPS ≥80%. In multivariate analysis, EGFR mutations were associated with a longer overall survival (HR= 0.6, p<0.001) and KRAS mutations with a shorter survival (HR=1.21, p=0.048).
Conclusions
KRAS mutations predict shorter survival for patients with advanced lung adenocarcinomas. The presence of EGFR and KRAS mutations define distinct subsets of patients with lung adenocarcinomas, and should be determined in patients upon diagnosis of advanced disease. Clinical trial reports should include EGFR and KRAS mutation status along with other prognostic factors.
doi:10.1002/cncr.27730
PMCID: PMC3966555  PMID: 22810899
non-small cell lung cancer; adenocarcinomas; EGFR; KRAS; survival; prognostic factors
19.  EGFR Exon 20 Insertion Mutations in Lung Adenocarcinomas: Prevalence, Molecular Heterogeneity, and Clinicopathologic Characteristics 
Molecular cancer therapeutics  2013;12(2):220-229.
In contrast to other primary EGFR mutations in lung adenocarcinomas, insertions in exon 20 of EGFR have been generally associated with resistance to EGFR tyrosine kinase inhibitors. Their molecular spectrum, clinicopathologic characteristics and prevalence are not well established. Tumors harboring EGFR exon 20 insertions were identified through an algorithmic screen of 1500 lung adenocarcinomas. Cases were first tested for common mutations in EGFR (exons 19 and 21) and KRAS (exon 2) and, if negative, further analyzed for EGFR exon 20 insertions. All samples underwent extended genotyping for other driver mutations in EGFR, KRAS, BRAF, NRAS, PIK3CA, MEK1 and AKT by mass spectrometry; a subset was evaluated for ALK rearrangements. We identified 33 EGFR exon 20 insertion cases (2.2%, 95% CI 1.6 to 3.1%), all mutually exclusive with mutations in the other genes tested (except PIK3CA). They were more common among never-smokers (p<0.0001). There was no association with age, sex, race, or stage. Morphologically, tumors were similar to those with common EGFR mutations, but with frequent solid histology. Insertions were highly variable in position and size, ranging from 3 to 12bp, resulting in 13 different insertions which, by molecular modeling, are predicted to have potentially different effects on erlotinib binding. EGFR exon 20 insertion testing identifies a distinct subset of lung adenocarcinomas, accounting for at least 9% of all EGFR mutated cases, representing the third most common type of EGFR mutation after exon 19 deletions and L858R. Insertions are structurally heterogeneous with potential implications for response to EGFR inhibitors.
doi:10.1158/1535-7163.MCT-12-0620
PMCID: PMC3714231  PMID: 23371856
EGFR exon 20; EGFR; epidermal growth factor receptor; lung adenocarcinoma; driver oncogenes
20.  Lungs don’t forget: Comparison of the KRAS and EGFR mutation profile and survival of “collegiate smokers” and never smokers with advanced lung cancers 
HYPOTHESIS
We hypothesize that among patients with lung cancers the KRAS/EGFR mutation profile and overall survival of “collegiate smokers” (former smokers who smoked between 101 lifetime cigarettes and 5 pack years) are distinct from those of never smokers and former smokers with ≥ 15 pack years.
METHODS
We collected age, sex, stage, survival, and smoking history for patients evaluated from 2004 to 2009 with advanced stage lung cancers and known KRAS/EGFR status. Mutation profile and overall survival were compared using Fisher’s exact test and log-rank test, respectively.
RESULTS
Data were available for 852 patients with advanced stage lung cancers with known KRAS/EGFR status. 6% were “collegiate smokers”, 36% were never smokers, and 30% were former smokers with ≥ 15 pack years. The mutation profile of “collegiate smokers” (15% KRAS mutations, 27% EGFR mutations) was distinct from those of never smokers (p < .001) and former smokers with ≥ 15 pack years (p < .001)and not significantly different from those of former smokers with 5 to 15 pack years (p = 0.9). Median overall survival for “collegiate smokers” was 25 months, compared to 32 months for never smokers (p = 0.4), 33 months for former smokers with 5–15 pack years (p = 0.48),and 21 months for former smokers with ≥ 15 pack years (p = 0.63).
CONCLUSIONS
“Collegiate smokers” with advanced stage lung cancers represent a distinct subgroup of patients with a higher frequency of KRAS mutations and lower frequency of EGFR mutations compared to never smokers. These observations reinforce the recommendation for routine mutation testing for all patients with lung cancers and that no degree of tobacco exposure is safe.
doi:10.1097/JTO.0b013e31827914ea
PMCID: PMC3534987  PMID: 23242442
Collegiate Smokers; non-small cell lung cancers; epidermal growth factor receptor mutation; KRAS mutation
21.  Secondary mutation in a coding mononucleotide tract in MSH6 causes loss of immunoexpression of MSH6 in colorectal carcinomas with MLH1/PMS2 deficiency 
Immunohistochemical staining for DNA mismatch repair proteins may be affected by various biological and technical factors. Staining variations that could potentially lead to erroneous interpretations have been recognized. A recently recognized staining variation is the significant reduction of staining for MSH6 in some colorectal carcinomas. The frequency and specific characteristics of this aberrant MSH6 staining pattern, however, have not been well analyzed. In this study of 420 colorectal carcinoma samples obtained from patients fulfilling the Revised Bethesda Guidelines, we detected 9 tumors (2%) showing extremely limited staining for MSH6 with positive staining present in <5% of the tumor cells. Our analyses showed that these tumors belonged to two distinct categories: (1) MLH1 and/or PMS2 protein-deficient carcinomas (n=5, including 1 with a pathogenic mutation in PMS2); and (2) MLH1, PMS2 and MSH2 normal but with chemotherapy or chemoradiation therapy before surgery (n=4). To test our hypothesis that somatic mutation in the coding region microsatellite of the MSH6 gene might be a potential underlying mechanism for such limited MSH6 staining, we evaluated frameshift mutation in a (C)8 tract in exon 5 of the MSH6 gene in seven tumors that had sufficient DNA for analysis, and detected mutation in four; all four tumors belonged to the MLH1/PMS2-deficient group. In conclusion, our data outline the main scenarios where significant reduction of MSH6 staining is more likely to occur in colorectal carcinoma, and suggest that somatic mutations of the coding region microsatellites of the MSH6 gene is an underlying mechanism for this staining phenomenon in MLH1/PMS2-deficient carcinomas.
doi:10.1038/modpathol.2012.138
PMCID: PMC3793326  PMID: 22918162
DNA mismatch repair; hereditary non-polyposis colorectal carcinoma; immunohistochemistry; Lynch syndrome; microsatellite instability
22.  ALK Rearrangements Are Mutually Exclusive with Mutations in EGFR or KRAS: An Analysis of 1,683 Patients with Non–Small Cell Lung Cancer 
Purpose
Anaplastic lymphoma kinase (ALK) gene rearrangements define a distinct molecular subset of non–small cell lung cancer (NSCLC). Recently, several case reports and small series have reported that ALK rearrangements can overlap with other oncogenic drivers in NSCLC in crizotinib-naïve and crizotinib-resistant cancers.
Experimental Design
We reviewed clinical genotyping data from 1,683 patients with NSCLC and investigated the prevalence of concomitant EGFR or KRAS mutations among patients with ALK-positive NSCLC. We also examined biopsy specimens from 34 patients with ALK-positive NSCLC after the development of resistance to crizotinib.
Results
Screening identified 301 (17.8%) EGFR mutations, 465 (27.6%) KRAS mutations, and 75 (4.4%) ALK rearrangements. EGFR mutations and ALK rearrangements were mutually exclusive. Four patients with KRAS mutations were found to have abnormal ALK FISH patterns, most commonly involving isolated 5′ green probes. Sufficient tissue was available for confirmatory ALK immunohistochemistry in 3 cases, all of which were negative for ALK expression. Among patients with ALK-positive NSCLC who acquired resistance to crizotinib, repeat biopsy specimens were ALK FISH positive in 29 of 29 (100%) cases. Secondary mutations in the ALK kinase domain and ALK gene amplification were observed in 7 of 34 (20.6%) and 3 of 29 (10.3%) cases, respectively. No EGFR or KRAS mutations were identified among any of the 25 crizotinib-resistant, ALK-positive patients with sufficient tissue for testing.
Conclusions
Functional ALK rearrangements were mutually exclusive with EGFR and KRAS mutations in a large Western patient population. This lack of overlap was also observed in ALK-positive cancers with acquired resistance to crizotinib.
doi:10.1158/1078-0432.CCR-13-0318
PMCID: PMC3874127  PMID: 23729361
23.  Prevalence, clinicopathologic associations and molecular spectrum of ERBB2 (HER2) tyrosine kinase mutations in lung adenocarcinomas 
Background
Activating mutations in the tyrosine kinase domain of HER2 (ERBB2) have been described in a subset of lung adenocarcinomas (ADCs) and are mutually exclusive with EGFR and KRAS mutations. The prevalence, clinicopathologic characteristics, prognostic implications, and molecular heterogeneity of HER2-mutated lung ADCs are not well established in US patients.
Experimental Design
Lung ADC samples (n=1478) were first screened for mutations in EGFR (exons 19 and 21) and KRAS (exon 2) and negative cases were then assessed for HER2 mutations (exons 19–20) using a sizing assay and mass spectrometry. Testing for additional recurrent point mutations in EGFR, KRAS, BRAF, NRAS, PIK3CA, MEK1 and AKT was performed by mass spectrometry. ALK rearrangements and HER2 amplification were assessed by FISH.
Results
We identified 25 cases with HER2 mutations, representing 6% of EGFR/KRAS/ALK-negative specimens. Small insertions in exon 20 accounted for 96% (24/25) of the cases. Compared to insertions in EGFR exon 20, there was less variability, with 83% (20/24) being a 12bp insertion causing duplication of amino acids YVMA at codon 775. Morphologically, 92% (23/25) were moderately or poorly differentiated ADC. HER2 mutation was not associated with concurrent HER2 amplification in 11 cases tested for both. HER2 mutations were more frequent among never-smokers (p<0.0001) but there were no associations with sex, race, or stage.
Conclusions
HER2 mutations identify a distinct subset of lung ADCs. Given the high prevalence of lung cancer worldwide and the availability of standard and investigational therapies targeting HER2, routine clinical genotyping of lung ADC should include HER2.
doi:10.1158/1078-0432.CCR-12-0912
PMCID: PMC3865806  PMID: 22761469
HER2; ERBB2; lung adenocarcinoma; EGFR; driver oncogenes
24.  Driver Mutations Determine Survival in Smokers and Never Smokers with Stage IIIB/IV Lung Adenocarcinomas 
Cancer  2012;118(23):5840-5847.
Background
We previously demonstrated that stage IIIB/IV non-small cell lung cancer (NSCLC) never smokers lived 50% longer than former/current smokers. This observation persisted after adjusting for age, performance status, and gender. We hypothesized that smoking-dependent differences in the distribution of driver mutations might explain differences in prognosis between these subgroups.
Methods
We reviewed 293 never smokers and 382 former/current smokers with lung adenocarcinoma who underwent testing for EGFR and KRAS mutations and rearrangements in ALK between 2009 and 2010. Clinical outcomes and patient characteristics were collected. Survival probabilities were estimated using the Kaplan-Meier method. Group comparison was performed with log-rank tests and Cox proportional hazards methods.
Results
While the overall incidence of these mutations was nearly identical (55% never smokers vs. 57% current/former smokers, p=0.48), there were significant differences in the distribution of mutations between these groups: EGFR mutations- 37% never smokers vs. 14% former/current smokers (p<0.0001); KRAS mutations- 4% never smokers vs. 43% former/current smokers (p<0.0001); ALK rearrangements- 12% never smokers vs. 2% former/current smokers (p<0.0001). Among never smokers and former/current smokers, prognosis differed significantly by genotype. Patients harboring KRAS mutations demonstrated the poorest survival. Smoking status, however, had no influence on survival within each genotype.
Conclusion
Never smokers and former/current smokers with lung adenocarcinomas are not homogeneous subgroups. Each is made up of individuals whose tumors have a unique distribution of driver mutations which are associated with different prognoses, irrespective of smoking history.
doi:10.1002/cncr.27637
PMCID: PMC3424296  PMID: 22605530
non-small cell lung cancer; adenocarcinoma; EGFR; KRAS; ALK; never smoker
25.  Quantitative assessment of intragenic receptor tyrosine kinase deletions in primary glioblastomas: their prevalence and molecular correlates 
Acta Neuropathologica  2013;127(5):747-759.
Intragenic deletion is the most common form of activating mutation among receptor tyrosine kinases (RTK) in glioblastoma. However, these events are not detected by conventional DNA sequencing methods commonly utilized for tumor genotyping. To comprehensively assess the frequency, distribution, and expression levels of common RTK deletion mutants in glioblastoma, we analyzed RNA from a set of 192 glioblastoma samples from The Cancer Genome Atlas for the expression of EGFRvIII, EGFRvII, EGFRvV (carboxyl-terminal deletion), and PDGFRAΔ8,9. These mutations were detected in 24, 1.6, 4.7, and 1.6 % of cases, respectively. Overall, 29 % (55/189) of glioblastomas expressed at least one RTK intragenic deletion transcript in this panel. For EGFRvIII, samples were analyzed by both quantitative real-time PCR (QRT-PCR) and single mRNA molecule counting on the Nanostring nCounter platform. Nanostring proved to be highly sensitive, specific, and linear, with sensitivity comparable or exceeding that of RNA seq. We evaluated the prognostic significance and molecular correlates of RTK rearrangements. EGFRvIII was only detectable in tumors with focal amplification of the gene. Moreover, we found that EGFRvIII expression was not prognostic of poor outcome and that neither recurrent copy number alterations nor global changes in gene expression differentiate EGFRvIII-positive tumors from tumors with amplification of wild-type EGFR. The wide range of expression of mutant alleles and co-expression of multiple EGFR variants suggests that quantitative RNA-based clinical assays will be important for assessing the relative expression of intragenic deletions as therapeutic targets and/or candidate biomarkers. To this end, we demonstrate the performance of the Nanostring assay in RNA derived from routinely collected formalin-fixed paraffin-embedded tissue.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-013-1217-3) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-013-1217-3
PMCID: PMC3984672  PMID: 24292886
EGFRvIII; GBM; Glioblastoma; Nanostring; RNA sequencing; TCGA

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