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Introduction Pulmonary invasive mucinous adenocarcinomas (IMAs) often present with spatially separate lung lesions. Clonal relationship between such lesions, particularly those involving contralateral lobes, is not well established. Here, we used comparative genomic profiling to address this question. Methods Patients with genomic analysis performed on two IMAs located in different lung regions were identified. Molecular assays included DNA-based next-generation sequencing (NGS) for 410 to 468 genes (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets), RNA-based NGS for 62 genes (Memorial Sloan Kettering-Fusion), or non-NGS assays. Results Comparative genomic profiling was performed on two separate IMAs in 24 patients, of whom 19 had contralateral lesions. Tumors from all but one patient shared matching driver alterations, including KRAS (n = 19), NRG1 (n = 2), ERBB2 (n = 1) or BRAF (n = 1). In addition, in patients with paired tumors profiled by NGS (n = 12), shared driver alterations were accompanied by up to 4 (average 2.6) other identical mutations, further supporting the clonal relationship between the tumors. Only in a single patient separate IMAs harbored entirely nonoverlapping mutation profiles, supporting clonally unrelated, distinct primary tumors. Notably, in a subset of patients (n = 3), molecular testing confirmed a clonal relationship between the original resected IMAs and subsequent contralateral IMA presenting after an extremely long latency (8.1–11.7 y). Conclusions Comparative molecular profiling supports that nearly all separate pulmonary IMA lesions represent intrapulmonary spread arising from a single tumor and documents a subset with a remarkably protracted course of intrapulmonary progression. This study reinforces the unique biology and clinical behavior of IMAs while further highlighting the value of genomic testing for clarifying the clonal relationship between multiple lung carcinomas.

Purpose: Chondrosarcomas are the second most common primary malignant bone tumors. Although histologic grade is the most important factor predicting the clinical outcome of chondrosarcoma, it is subject to interobserver variability. Isocitrate dehydrogenase 1 (IDH1) and IDH2 hotspot mutations were recently found to be frequently mutated in central chondrosarcomas. However, a few published articles have been controversial regarding the association between IDH1/IDH2 mutation status and clinical outcomes in chondrosarcomas. Experimental Design: We performed hotspot sequencing of IDH1 and IDH2 genes in 89 central chondrosarcomas and targeted next-generation sequencing in 54 of them, and then correlated the IDH1/IDH2 mutation status with the patient's clinical outcome. Results: Although no association was discovered between IDH mutation status and the patient's overall survival, IDH1/IDH2 mutation was found to be associated with longer relapse-free and metastasis-free survival in high-grade chondrosarcomas. Genomic profiling reveals TERT gene amplification and ATRX mutation, for the first time, in addition to TERT promoter mutation in a subset (6/30, 20%) of high-grade and dedifferentiated chondrosarcomas. These abnormalities in telomere genes are concurrent with IDH1/IDH2 mutation and with CDKN2A/2B deletion or TP53 mutation, suggesting a possible association and synergy among these genes in chondrosarcoma progression. We found 21% of patients with chondrosarcoma also had histories of second malignancies unrelated to cartilaginous tumors, suggesting possible unknown genetic susceptibility to chondrosarcoma. Conclusions: IDH1/IDH2 mutations are associated with longer relapse-free and metastasis-free survival in high-grade chondrosarcomas, and they tend to co-occur with TERT mutations and with CDKN2A/2B and TP53 alterations in a subset of high-grade chondrosarcomas.

PURPOSE Mitogen-activated protein kinase pathway–activating mutations occur in the majority of colorectal cancer (CRC) cases and show mutual exclusivity. We identified 47 epidermal growth factor receptor/BRAF inhibitor-naive CRC patients with dual RAS hotspot/ BRAF V600E mutations (CRC-DD) from a cohort of 4,561 CRC patients with clinical next-generation sequencing results. We aimed to define the molecular phenotypes of the CRC-DD and to test if the dual RAS hotspot/BRAF V600E mutations coexist within the same cell. MATERIALS AND METHODS We developed a single-cell genotyping method with a mutation detection rate of 96.3% and a genotype prediction accuracy of 92.1%. Mutations in the CRC-DD cohort were analyzed for clonality, allelic imbalance, copy number, and overall survival. RESULTS Application of single-cell genotyping to four CRC-DD revealed the co-occurrence of both mutations in the following percentages of cells per case: NRAS G13D/ KRAS G12C, 95%; KRAS G12D/ NRAS G12V, 48%; BRAF V600E/ KRAS G12D, 44%; and KRAS G12D/ NRAS G13V, 14%, respectively. Allelic imbalance favoring the oncogenic allele was less frequent in CRC-DD (24 of 76, 31.5%, somatic mutations) compared with a curated cohort of CRC with a single-driver mutation (CRC-SD; 119 of 232 mutations, 51.3%; P = .013). Microsatellite instability–high status was enriched in CRC-DD compared with CRC-SD (23% v 11.4%, P = .028). Of the seven CRC-DD cases with multiregional sequencing, five retained both driver mutations throughout all sequenced tumor sites. Both CRC-DD cases with discordant multiregional sequencing were microsatellite instability–high. CONCLUSION Our findings indicate that dual-driver mutations occur in a rare subset of CRC, often within the same tumor cells and across multiple tumor sites. Their presence and a lower rate of allelic imbalance may be related to dose-dependent signaling within the mitogen-activated protein kinase pathway.

Mosaic mutations in normal tissues can occur early in embryogenesis and be associated with hereditary cancer syndromes when affecting cancer susceptibility genes (CSG). Their contribution to apparently sporadic cancers is currently unknown. Analysis of paired tumor/blood sequencing data of 35,310 patients with cancer revealed 36 pathogenic mosaic variants affecting CSGs, most of which were not detected by prior clinical genetic testing. These CSG mosaic variants were consistently detected at varying variant allelic fractions in microdissected normal tissues (n = 48) from distinct embryonic lineages in all individuals tested, indicating their early embryonic origin, likely prior to gastrulation, and likely asymmetrical propagation. Tumor-specific biallelic inactivation of the CSG affected by a mosaic variant was observed in 91.7% (33/36) of cases, and tumors displayed the hallmark pathologic and/or genomic features of inactivation of the respective CSGs, establishing a causal link between CSG mosaic variants arising in early embryogenesis and the development of apparently sporadic cancers. Significance: Here, we demonstrate that mosaic variants in CSGs arising in early embryogenesis contribute to the oncogenesis of seemingly sporadic cancers. These variants can be systematically detected through the analysis of tumor/normal sequencing data, and their detection may affect therapeutic decisions as well as prophylactic measures for patients and their offspring. See related commentary by Liggett and Sankaran, p. 889. This article is highlighted in the In This Issue feature, p. 873

Purpose:Invasive mucinous adenocarcinoma (IMA) is a unique subtype of lung adenocarcinoma, characterized genomically by frequent KRAS mutations or specific gene fusions, most commonly involving NRG1. Comprehensive analysis of a large series of IMAs using broad DNA- and RNA-sequencing methods is still lacking, and it remains unclear whether molecular subtypes of IMA differ clinicopathologically.Experimental Design:A total of 200 IMAs were analyzed by 410-gene DNA next-generation sequencing (MSK-IMPACT; n = 136) or hotspot 8-oncogene genotyping (n = 64). Driver-negative cases were further analyzed by 62-gene RNA sequencing (MSK-Fusion) and those lacking fusions were further tested by whole-exome sequencing and whole-transcriptome sequencing (WTS).Results:Combined MSK-IMPACT and MSK-Fusion testing identified mutually exclusive driver alterations in 96% of IMAs, including KRAS mutations (76%), NRG1 fusions (7%), ERBB2 alterations (6%), and other less common events. In addition, WTS identified a novel NRG2 fusion (F11R–NRG2). Overall, targetable gene fusions were identified in 51% of KRAS wild-type IMAs, leading to durable responses to targeted therapy in some patients. Compared with KRAS-mutant IMAs, NRG1-rearranged tumors exhibited several more aggressive characteristics, including worse recurrence-free survival (P < 0.0001).Conclusions:This is the largest molecular study of IMAs to date, where we demonstrate the presence of a major oncogenic driver in nearly all cases. This study is the first to document more aggressive characteristics of NRG1-rearranged IMAs, ERBB2 as the third most common alteration, and a novel NRG2 fusion in these tumors. Comprehensive molecular testing of KRAS wild-type IMAs that includes fusion testing is essential, given the high prevalence of alterations with established and investigational targeted therapies in this subset.

BACKGROUND: Liquid biopsy for plasma circulating tumor DNA (ctDNA) next-generation sequencing (NGS) is commercially available and increasingly adopted in clinical practice despite a paucity of prospective data to support its use. METHODS: Patients with advanced lung cancers who had no known oncogenic driver or developed resistance to current targeted therapy (n = 210) underwent plasma NGS, targeting 21 genes. A subset of patients had concurrent tissue NGS testing using a 468-gene panel (n = 106). Oncogenic driver detection, test turnaround time (TAT), concordance, and treatment response guided by plasma NGS were measured. All statistical tests were two-sided. RESULTS: Somatic mutations were detected in 64.3% (135/210) of patients. ctDNA detection was lower in patients who were on systemic therapy at the time of plasma collection compared with those who were not (30/70, 42.9% vs 105/140, 75.0%; OR = 0.26, 95% CI = 0.1 to 0.5, P

Background: Lung cancer is a major cause of death in HIV-infected (HIV+) persons. In this study, we compared the prevalence of tumour EGFR and KRAS mutations in a cohort of lung adenocarcinoma patients by HIV status. Methods: We collected data from 55 HIV+ patients with lung adenocarcinoma matched to 136 uninfected comparators. We compared the prevalence of EGFR and KRAS mutations by HIV status. We then compared survival by HIV status and by cancer mutation status among HIV+ subjects. Results: Presence of KRAS and EGFR genetic alterations did not vary by HIV status (all P>0.1). There was no difference in overall survival by HIV status or by mutation status among HIV+ subjects. Conclusions: We found no major differences in the prevalence of EGFR or KRAS lung adenocarcinoma mutations by HIV status, suggesting that mutational testing should be conducted similarly regardless of the HIV status.

Background: Plasma cfDNA evaluation at acquired resistance to targeted therapies in lung cancer is routine, however, reports of extended clinical application and pitfalls in laboratory practice are still limited. In this study we describe our experience with cfDNA testing using EGFR T790M as a prototype. Methods: Patients with metastatic EGFR-mutant NSCLC patients who underwent plasma EGFR T790M testing at acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI) from January 2016 through August 2017 were identified. Molecular laboratory records were reviewed to assess performance of testing by digital PCR, concordance between plasma and tissue testing, turnaround time (TAT), plasma T790M variant allele frequency (VAF), and its correlations with metastatic sites and clinical outcomes. Results: 177 patients underwent T790M cfDNA testing during this period. Plasma T790M was positive in 32% of patients. The median TAT was shorter for plasma T790M compared to tissue PCR (9 vs. 15 days, p p = .4). Plasma T790M status correlated with a higher number of metastatic sites (4 vs. 3, p p = .0002). Conclusion: Plasma EGFR T790M testing had shorter TAT compared to tissue testing, however, it was longer than anticipated. Test sensitivity is higher in patients with osseous metastases and with higher metastatic burden suggesting a more limited role for early detection. T790M VAF was not associated with clinical outcomes.

Introduction Half of inflammatory myofibroblastic tumors (IMTs) regardless of anatomic location harbor anaplastic lymphoma kinase gene (ALK) rearrangements and overexpress anaplastic lymphoma kinase protein. The wide application of next-generation sequencing and the clinical benefit to tyrosine kinase inhibitors have opened new opportunities for investigation of ALK-negative IMTs. Methods In this study, we have investigated a series of pediatric and adult thoracic IMTs for abnormalities in a wide spectrum of actionable kinases by applying a variety of molecular and next-generation sequencing techniques, including fluorescence in situ hybridization (FISH), targeted RNA sequencing, and NanoString assay. Results There were 33 patients with thoracic IMTs, including five children; their mean age was 37. The tumors showed a monomorphic spindle cell phenotype, except for one with an epithelioid morphologic pattern and moderate to severe atypia. By immunohistochemistry, 24 tumors were ALK positive, and 19 of the 24 showed ALK rearrangements and one ret proto-oncogene gene (RET) rearrangement by FISH. RNA sequencing was performed in the remaining four cases lacking ALK abnormalities by FISH, revealing ALK fusions involving tropomyosin 4 gene (TMP4) and echinoderm microtubule associated protein like 4 gene (EML4) as partner in three cases. NanoString assay was performed in the remaining case, revealing ALK alternative transcription initiation (ALKATI). Nine cases lacking ALK abnormalities were further tested by FISH or targeted RNA sequencing, revealing ROS1 rearrangement in six cases and ETS variant 6 gene (ETV6)–neurotrophic receptor tyrosine kinase 3 gene (NTRK3) fusion in three cases, respectively. Conclusions By using a battery of complementary molecular techniques, we have shown that all the thoracic IMTs harbored a tyrosine kinase abnormality, with 30% involving a kinase gene other than ALK, including ROS1, NTRK3, and RET gene fusions. We have also described for the first time ALKATI-induced ALK oncogenic activation in IMTs.

Targeted therapy for metastatic colorectal carcinoma consists of anti-EGFR therapy for patients with RAS/RAF wild-type tumors. However, the response rate remains low, suggesting the presence of alternative drivers possibly also representing potential therapeutic targets. We investigated receptor tyrosine kinase (RTK) alterations and MAP2K1 (MEK1) mutations in a large cohort of colorectal carcinoma patients studied by Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets and The Cancer Genome Atlas, focusing on amplifications, fusions, and hotspot mutations in RTK genes and MAP2K1. RTK gene amplifications were confirmed with FISH and immunohistochemical (IHC) staining. Among 751 colorectal carcinoma cases with next-generation sequencing data, 7% and 1% of colorectal carcinoma harbored RTK alterations and MAP2K1 hotspot mutations (n = 7), respectively. RTK-altered cases had fewer concurrent RAS/RAF mutations (P = 0.003) than RTK/MAP2K1 wild-type colorectal carcinoma. MAP2K1-mutated colorectal carcinoma showed no RAS/RAF mutations. ERBB2 (n = 32) and EGFR (n = 13) were the most frequently altered RTKs, both activated by amplification and/or hotspot mutations. Three RTK fusions were identified: NCOA4-RET, ERBB2-GRB7, and ETV6-NTRK3. Only 1 of 6 patients with an RTK or MAP2K1 alteration who received anti-EGFR and/or anti-ERBB2 therapy demonstrated stable disease; the rest progressed immediately. Overall, RTK alterations and MAP2K1 mutations occur in approximately 8% of colorectal carcinoma. In spite of the usual absence of RAS/RAF mutations, response to anti-EGFR and/or anti-ERBB2 therapy was poor in this limited group. Larger studies are warranted to further define these kinase alterations as novel therapeutic targets in colorectal carcinoma and as negative predictors of response to anti-EGFR therapy. Implications: Targetable kinase alterations were identified in a subset of advanced colorectal carcinoma patients, preferentially associated with wild-type RAS/RAF, and may predict poor response to standard anti-EGFR therapy. Mol Cancer Res; 14(3); 296–301. ©2015 AACR.

The PI3K/AKT/mTOR pathway is activated through multiple mechanisms in colorectal carcinoma. Here, the clinicopathologic and molecular features of AKT1 E17K–mutated colorectal carcinoma in comparison with PIK3CA-mutated colorectal carcinoma are described in detail. Interestingly, in comparison with PIK3CA mutants, AKT1 E17K was significantly associated with mucinous morphology and concurrent BRAF V600E mutation. Among PIK3CA mutants, exon 21 mutations were significantly associated with BRAF V600E mutation, MSI-H status, and poor differentiation, while exon 10 mutations were associated with KRAS/NRAS mutations. Three of four AKT1 mutants with data from both primary and metastatic lesions had concordant AKT1 mutation status in both. Both AKT1- and PIK3CA-mutant colorectal carcinoma demonstrated frequent loss of PTEN expression (38% and 34%, respectively) and similar rates of p-PRAS 40 expression (63% and 50%, respectively). Both patients with AKT1 E17K alone had primary resistance to cetuximab, whereas 7 of 8 patients with PIK3CA mutation alone experienced tumor shrinkage or stability with anti-EGFR therapy. These results demonstrate that AKT1 E17K mutation in advanced colorectal carcinoma is associated with mucinous morphology, PIK3CA wild-type status, and concurrent RAS/RAF mutations with similar pattern to PIK3CA exon 21 mutants. Thus, AKT1 E17K mutations contribute to primary resistance to cetuximab and serve as an actionable alteration. Implications: This first systematic study of AKT1 and PIK3CA hotspot mutations and their association with cetuximab resistance and BRAF V600E mutation has important ramifications for the development of personalized medicine, particularly in identifying patient candidates for PI3K or AKT inhibitors. Mol Cancer Res; 13(6); 1003–8. ©2015 AACR.

Purpose: Genetic alterations affecting the MAPK/ERK pathway are common in lung adenocarcinoma (LAD). Early steps of the signaling pathway are most often affected with EGFR, KRAS, and BRAF mutations encompassing more than 70% of all alterations. Somatic mutations in MEK1, located downstream of BRAF, are rare and remain poorly defined as a distinct molecular subset. Experimental Design: Tumors harboring MEK1 mutations were identified through targeted screening of a large LAD cohort concurrently interrogated for recurrent mutations in MEK1, EGFR, KRAS, BRAF, ERBB2/HER2, NRAS, PIK3CA, and AKT. Additional cases were identified through a search of publically available cancer genomic datasets. Mutations were correlated with patient characteristics and treatment outcomes. Overall survival was compared with stage-matched patients with KRAS- and EGFR-mutant LADs. Results: We identified 36 MEK1-mutated cases among 6,024 LAD (0.6%; 95% confidence interval, 0.42–0.85). The majority of patients were smokers (97%, n = 35/36). There was no association with age, sex, race, or stage. The most common mutations were K57N (64%, 23/36) followed by Q56P (19%, 7/36), all mutually exclusive with other driver mutations in the targeted panel. Transversions G:C>T:A were predominant (89%, 31/35), in keeping with smoking-associated DNA damage. Additional less common somatic mutations were identified in the kinase domain, all of which are predicted to converge into a single interaction area based on in silico 3D modeling. Conclusions: MEK1 mutations define a distinct subset of lung cancers (∼1%) with potential sensitivity to MEK inhibitors. Mutations are predominantly transversions, in keeping with a strong association with smoking. Clin Cancer Res; 21(8); 1935–43. ©2014 AACR.

BACKGROUND RAS and PIK3CA mutations in metastatic colorectal cancer (mCRC) have been associated with worse survival. We sought to evaluate the impact of RAS and PIK3CA mutations on cumulative incidence of metastasis to potentially curable sites of liver and lung and other sites such as bone and brain. METHODS We performed a computerized search of the electronic medical record of our institution for mCRC cases genotyped for RAS or PIK3CA mutations from 2008 to 2012. Cases were reviewed for patient characteristics, survival, and site-specific metastasis. RESULTS Among the 918 patients identified, 477 cases were RAS wild type, and 441 cases had a RAS mutation (394 at KRAS exon 2, 29 at KRAS exon 3 or 4, and 18 in NRAS). RAS mutation was significantly associated with shorter median overall survival (OS) and on multivariate analysis independently predicted worse OS (HR, 1.6; P

Purpose: In contrast to the numerous broad screens for oncogene mutations in adult cancers, few such screens have been conducted in pediatric solid tumors. To identify novel mutations and potential therapeutic targets in pediatric cancers, we conducted a high-throughput Sequenom-based analysis in large sets of several major pediatric solid cancers, including neuroblastoma, Ewing sarcoma, rhabdomyosarcoma (RMS), and desmoplastic small round cell tumor (DSRCT). Experimental Design: We designed a highly multiplexed Sequenom-based assay to interrogate 275 recurrent mutations across 29 genes. Genomic DNA was extracted from 192 neuroblastoma, 75 Ewing sarcoma, 89 RMS, and 24 DSRCT samples. All mutations were verified by Sanger sequencing. Results: Mutations were identified in 13% of neuroblastoma samples, 4% of Ewing sarcoma samples, 21.1% of RMS samples, and no DSRCT samples. ALK mutations were present in 10.4% of neuroblastoma samples. The remainder of neuroblastoma mutations involved the BRAF, RAS, and MAP2K1 genes and were absent in samples harboring ALK mutations. Mutations were more common in embryonal RMS (ERMS) samples (28.3%) than alveolar RMS (3.5%). In addition to previously identified RAS and FGFR4 mutations, we report for the first time PIK3CA and CTNNB1 (β-catenin) mutations in 5% and 3.3% of ERMS, respectively. Conclusions: In ERMS, Ewing sarcoma, and neuroblastoma, we identified novel occurrences of several oncogene mutations recognized as drivers in other cancers. Overall, neuroblastoma and ERMS contain significant subsets of cases with nonoverlapping mutated genes in growth signaling pathways. Tumor profiling can identify a subset of pediatric solid tumor patients as candidates for kinase inhibitors or RAS-targeted therapies. Clin Cancer Res; 18(3); 748–57. ©2011 AACR.

Mutations in the MET exon 14 RNA splice acceptor and donor sites, which lead to exon skipping, deletion of the juxtamembrane domain containing the CBL E3-ubiquitin ligase-binding site, and decreased turnover of the resultant aberrant MET protein, were previously reported to be oncogenic in preclinical models. We now report responses to the MET inhibitors crizotinib and cabozantinib in four patients with stage IV lung adenocarcinomas harboring mutations leading to MET exon 14 skipping, highlighting a new therapeutic strategy for the 4% of lung adenocarcinoma patients whose tumors harbor this previously underappreciated genetic alteration. Significance: Oncogenic mutations in the MET exon 14 splice sites that cause exon 14 skipping occur in 4% of lung adenocarcinomas. We report responses to the MET inhibitors crizotinib and cabozantinib in patients with lung adenocarcinomas harboring MET exon 14 splice site mutations, identifying a new potential therapeutic target in this disease. Cancer Discov; 5(8); 842–9. ©2015 AACR. See related commentary by Ma, p. 802. See related article by Frampton et al., p. 850. This article is highlighted in the In This Issue feature, p. 783

A 75 year-old woman, 50 pack-year ex-smoker, presented with a lung nodule on a routine follow-up chest CT scan for prior colon adenocarcinoma (Figure 1A). A wedge resection revealed an apparently single 1.5 cm nodule on gross examination. Microscopic examination revealed an adenocarcinoma of lung origin, as supported by morphology (Figure 1B) and diffusely positive immunohistochemistry for TTF-1 and Napsin A. The tumor consisted of two geographically-contiguous areas - a 6 mm area with solid and acinar patterns, and a peripheral 9 mm area with a predominantly lepidic pattern (Figure 1C,D). Although the two areas could represent heterogeneous histology in a single adenocarcinoma, the dumbbell shape of the lesion raised the possibility of a collision of two immediately-adjacent separate tumors. The two areas were dissected out and submitted for EGFR and KRAS molecular testing separately. Sequencing revealed a KRAS G12A mutation in the 6 mm area, and a novel KRAS L19F/T20S double-mutation in the 9 mm are (Figure 2A). The latter was confirmed to represent same-allele double-mutation - a complex compound substitution (L19_T20>FS) - by next-generation sequencing (Figure 2B), resulting in potential functional cooperativity based on amino acid modeling (Figure 3). Overall, these molecular data established that the 6 mm and 9 mm areas had distinct KRAS mutations, thus representing two colliding synchronous primaries rather than histologically-heterogeneous areas of a single adenocarcinoma. Figure 1 (A) Chest CT scan: apparently single nodule (arrow) with solid and ground-glass components. (B) Low-power and (C, D) higher power microscopic images of H&E-stained section, revealing two geographically-contiguous areas with distinct growth patterns ... Figure 2 Sanger sequencing electropherograms, revealing a KRAS G12A(c.35G>C) mutation in the 6 mm nodule (A) and KRAS L19F(c.57G>T)/T20S(c.58A>T) double mutation in the 9 mm nodule (B). (C) Split-screen view of aligned sequencing reads ... Figure 3 Amino acid modeling of KRAS L19F/T20S (L19_T20>FS) double mutation. L19F and T20S are highly conserved and belong to the core region of KRAS. L19 is predicted to interact with GTP/GDP-binding residues (N116, A146, and K16 that in turn interact ... This case illustrates a rare phenomenon of collision tumors, in which two distinct tumors co-occur at the same or immediately-adjacent anatomic locations.1 The exact incidence of collision of synchronous lung carcinomas in unknown, but given that 4–20% of patients with lung cancer have multiple primary tumors,2 the odds of two tumors occurring immediately-adjacent to each other are not negligible. As illustrated here, collisions are inapparent on radiologic and gross examination. While microscopic examination is generally effective at identifying collisions of different tumor types, recognition of this phenomenon for synchronous lung adenocarcinomas is particularly challenging because these tumors are at-baseline highly heterogeneous (i.e. composed of a mixture of lepidic, acinar, solid etc patterns), making it difficult to distinguish histologic heterogeneity in a single adenocarcinoma from two colliding, contiguous tumors. Peripheral lepidic pattern is commonly seen in lung adenocarcinomas. In this case, a dumbbell-shaped outline of the lesion raised the possibility of a collision, but a definitive distinction between a single morphologically-heterogeneous adenocarcinoma versus a collision could not be made based on microscopic findings. This case demonstrates of the utility of driver mutation analysis in elucidating tumor clonal relationships in the setting of a possible collision, similar to what has been recently proposed for the utility of molecular profiling for the distinction of synchronous/metachronous primaries from intrapulmonary metastases.3 We also illustrate the use of next-generation sequencing to determine that the two KRAS mutations in the 9 mm nodule resided on same allele, thus excluding the possibility they were a result of yet another unsuspected collision of tumors with distinct KRAS mutations. In the era of predictive molecular testing, collision may be an under-recognized, albeit rare, cause for aberrant driver mutation profiles in lung adenocarcinomas. Specifically, while there is strong evidence that major driver mutations in EGFR and KRAS are distributed homogeneously throughout individual tumors, there is a number of reports to the contrary. One explanation for such findings has been geographic variability in mutant to wild-type allele ratio resulting from variable amplification of the mutant allele and/or variable admixture of non-neoplastic cells, leading to inconsistent detection of mutations (i.e. mutation ‘pseudo-heterogeneity’).4,5 This case illustrates another potential mechanism for mutation ‘pseudo-heterogeneity’. In our case, random microdissection with a presumption that all dissected samples were derived from a single tumor would have resulted in the impression of intra-tumoral heterogeneity of KRAS mutations. Alternatively, molecular testing of the conglomerate nodule in the absence of microdissection would have resulted in ‘pseudo-multiplicity’ of KRAS G12A and L19F/T20S mutations. In contradistinction, the L19F/T20S double-mutation illustrates a rare example of true functionally-significant mutation multiplicity. In summary, this case illustrates unsuspected collision as a previously unreported potential cause of aberrant molecular findings in lung adenocarcinomas, and highlights the importance of careful histologic examination of tissue submitted for molecular testing.

EGFR-mutant lung cancers represent a paradigm for the use of tyrosine kinase inhibitors (TKIs) to treat molecular subsets of cancer, with randomized trials demonstrating the efficacy of first-generation, reversible epidermal growth factor receptor (EGFR) TKIs. However, acquired resistance invariably develops, and rebiopsy of patients with clinical progression has elucidated EGFR T790M mutation as the major resistance mechanism.1 To address this clinical challenge, third-generation pyrimidine-based EGFR TKIs have been designed to have selectivity for EGFR T790M over wild-type EGFR.2 They form a covalent bond with cysteine 797 in the adenosine triphosphate–binding cleft. Early-phase clinical trials have demonstrated their efficacy in patients with double-mutant tumors (EGFR L858R/T790M and ex19del/T790M) and acquired resistance to first-generation EGFR inhibitors.3 Specificity for EGFR T790M may be the result of hydrophobic interactions between the bulky methionine moiety of EGFR T790M and these pyrimidine-based drugs. Mechanisms of resistance to these third-generation EGFR TKIs have been identified in preclinical in vitro models, but none have so far been identified in patients. Mutations at the EGFR C797 codon, located within the kinase-binding site, are a predicted resistance mechanism to irreversible EGFR inhibitors also confirmed in vitro.4 Loss of the potential for covalent bond formation at position 797 by the missense mutation C797S results in a markedly reduced cellular potency of this class of TKIs.5 Interestingly, an analogous cysteine-to-serine mutation is a mechanism of resistance to the irreversible Bruton tyrosine kinase inhibitor ibrutinib in patients with chronic lymphocytic leukemia.6

Molecular and genetic evidence suggests that DNA repair pathways may contribute to lymphoma susceptibility. Several studies have examined the association of DNA repair genes with lymphoma risk, but the findings from these reports have been inconsistent. Here we provide the results of a focused analysis of genetic variation in DNA repair genes and their association with the risk of non-Hodgkin's lymphoma (NHL). With a population of 1,297 NHL cases and 1,946 controls, we have performed a two-stage case/control association analysis of 446 single nucleotide polymorphisms (SNPs) tagging the genetic variation in 81 DNA repair genes. We found the most significant association with NHL risk in the ATM locus for rs227060 (OR = 1.27, 95% CI: 1.13-1.43, p = 6.77×10(-5)), which remained significant after adjustment for multiple testing. In a subtype-specific analysis, associations were also observed for the ATM locus among both diffuse large B-cell lymphomas (DLBCL) and small lymphocytic lymphomas (SLL), however there was no association observed among follicular lymphomas (FL). In addition, our study provides suggestive evidence of an interaction between SNPs in MRE11A and NBS1 associated with NHL risk (OR = 0.51, 95% CI: 0.34-0.77, p = 0.0002). Finally, an imputation analysis using the 1,000 Genomes Project data combined with a functional prediction analysis revealed the presence of biologically relevant variants that correlate with the observed association signals. While the findings generated here warrant independent validation, the results of our large study suggest that ATM may be a novel locus associated with the risk of multiple subtypes of NHL.

e18542 Background: Somatic BAP1 mutations are found in nearly a quarter of MM tumors and germline BAP1 mutations define a new cancer syndrome characterized by familial mesothelioma, uveal melanoma,...

7120 Background: There is a high frequency of activating mutations in proteins of the Ras/Raf/MEK/ERK pathway in melanoma and other solid tumors. The BRAF V600E mutation has been found recently to be highly prevalent in ECD, a rare non-Langerhans cell histiocytosis with poor prognosis, as well as Langerhans cell histiocytosis (LCH). Treatment of patients with ECD and the BRAF V600E mutation with vemurafenib has been associated with unprecedented and dramatic response in a few cases. Methods: We present a 66 year-old man evaluated for several months of cognitive and motor decline. He was found to have multifocal enhancing lesions in the cerebral meninges, multiple masses in the abdomen and sacrum, and abnormal nuclear uptake in the long bones of the legs. Results: Biopsy of a renal mass demonstrated a foamy CD68+/CD1a- histiocytic infiltrate, consistent with ECD. Interrogation of tumor tissue with the Sequenom MassArray system demonstrated absence of the BRAF V600E mutation but presence of the NRAS Q61R mutation. Conclusions: This is, to our knowledge, the first report of an activating NRAS mutation in ECD. The finding of an oncogenic NRAS mutation in ECD further supports the hypothesis that this disease is driven by activation of the Ras/Raf/MEK/ERK pathway. Further investigation into the role of this pathway in ECD and LCH is warranted and may open new opportunities for targeted therapies for these disorders.

10524 Background: As more therapies targeting genomic alterations become available, genotyping (e.g., by Sequenom) is increasingly performed in tumor types where mutational status may drive treatment choice. Next-generation sequencing (NGS) technology can expand on genotyping of individual base pairs because it can detect mutations across entire exons, copy changes and fusion genes. However, for NGS to be clinically viable, it must be made compatible with FFPE tissues and shown concordant with best current diagnostic methods. Methods: To explore a potential clinical role for NGS, we selected 120 FFPE specimens (68 NSCLC, 32 CRC, 20 melanoma) previously tested for 97 oncogenic mutations in 8 oncogenes by Sequenom, and sequenced all exons of 182 cancer genes. Genotyping and sequencing were both performed in CLIA compliant labs. DNA was extracted from 4x 10μ unstained sections from the diagnostic FFPE block, followed by library construction and hybridization capture of 3230 exons and 37 commonly rearranged introns. Average coverage of >900X uniquely-mapping reads was obtained. Sequence data were analyzed for all genomic alterations and examined for potentially actionable mutations. Results: High concordance was noted between Sequenom and NGS: 103 and 105 mutations were called by the two technologies, respectively, at mutually tested sites, with 97 mutation calls in common. Notably, mutant allele frequencies in concordant calls ranged as low as 2% by NGS, highlighting the sensitivity of detection enabled by both approaches. Furthermore, in 45/120 (38%) specimens, NGS revealed additional alterations that may confer sensitivity or resistance to approved or experimental targeted therapies and thus plausibly influence treatment decisions. These included 39 copy changes or loss-of-function variants best assayed by an NGS approach. Conclusions: Our results demonstrate technical feasibility and highlight potential benefits of comprehensive cancer gene characterization through next-generation sequencing of clinical FFPE specimens. As NGS is the most practical means to detect all classes of somatic alteration in a small, clinically relevant sample, we suggest that this type of testing will become an essential component of patient care.

As genomic data accumulate at an ever-increasing rate, it is becoming evident that a comprehensive description of molecular aberrations that define individual patients’ tumors will prove useful to determine optimal therapeutic strategies. Several platforms are currently in use for clinical molecular diagnostics testing, including PCR, Sanger sequencing, restriction fragment length polymorphism analysis, and mass spectrometric genotyping (Sequenom). Massively parallel sequencing (MPS) technology has the potential to expand upon Sequenom genotyping because it allows for the identification of mutations across entire exons (rather than single base pairs) as well as copy gains, losses and gene fusions. However, for MPS to be considered a viable clinical strategy, it must first be shown to be compatible with formalin-fixed, paraffin embedded (FFPE) tissue across a range of tumor types, sizes, and cellularities. Also, it must exhibit high concordance with mutation profiles derived using the current best diagnostic methods available. To explore the clinical utility of MPS, we selected 71 surgically resected FFPE tumors that had previously been tested for approximately 100 oncogenic mutations in 8 oncogenes by Sequenom genotyping and subjected them to targeted DNA sequencing of 189 cancer-related genes. DNA was extracted from four 10-micron unstained sections from the diagnostic FFPE block (yielding a minimum of 250 nanograms per case), followed by sequencing library construction and hybridization-based capture of 3230 exons and 37 intronic intervals. Deep sequencing was performed, yielding an average coverage of >750X for uniquely-mapping reads. Sequence data were analyzed for single nucleotide variants and small insertions and deletions. High concordance was noted between Sequenom and MPS: 62 and 65 mutations were called by the two technologies, respectively, at mutually tested sites, with 60 mutation calls in common. Notably, mutant allele frequencies in these concordant calls ranged as low as 4% by MPS, highlighting the sensitivity of detection enabled by both approaches. The few discordant mutation calls exhibited no or weak evidence in the other dataset, possibly due to local tumor heterogeneity. Further, MPS revealed 73 sequence variants at additional sites of known recurrent somatic mutations and 30 loss-of-function variants in key tumor suppressor genes not tested by Sequenom. Many of these variants represent plausibly actionable mutations that could influence treatment decisions. Thus, we conclude that: (1) MPS exhibits high concordance with current best methods and is a viable strategy for clinical diagnostics, and (2) MPS captures additional variants not typically interrogated in the current clinical setting but with potential implications for the selection of approved and/or experimental targeted therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 965. doi:1538-7445.AM2012-965

8033 Background: KRAS mutations define the largest subset of oncogene-driven lung adenocarcinomas (25-30%). Among patients with KRAS mutations, their clinical course during treatment is heterogeneo...