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Small cell lung cancer (SCLC) is an aggressive malignancy characterized by early metastasis and extreme lethality. The backbone of SCLC treatment over the past several decades has been platinum-based doublet chemotherapy, with the recent addition of immunotherapy providing modest benefits in a subset of patients. However, nearly all patients treated with systemic therapy quickly develop resistant disease, and there is an absence of effective therapies for recurrent and progressive disease. Here we conducted CRISPR-Cas9 screens using a druggable genome library in multiple SCLC cell lines representing distinct molecular subtypes. This screen nominated exportin-1, encoded by XPO1, as a therapeutic target. XPO1 was highly and ubiquitously expressed in SCLC relative to other lung cancer histologies and other tumor types. XPO1 knockout enhanced chemosensitivity, and exportin-1 inhibition demonstrated synergy with both first- and second-line chemotherapy. The small molecule exportin-1 inhibitor selinexor in combination with cisplatin or irinotecan dramatically inhibited tumor growth in chemonaïve and chemorelapsed SCLC patient-derived xenografts, respectively. Together these data identify exportin-1 as a promising therapeutic target in SCLC, with the potential to markedly augment the efficacy of cytotoxic agents commonly used in treating this disease. Significance: CRISPR-Cas9 screening nominates exportin-1 as a therapeutic target in SCLC, and exportin-1 inhibition enhances chemotherapy efficacy in patient-derived xenografts, providing a novel therapeutic opportunity in this disease.

Lineage plasticity is implicated in treatment resistance in multiple cancers. In lung adenocarcinomas (LUAD) amenable to targeted therapy, transformation to small cell lung cancer (SCLC) is a recognized resistance mechanism. Defining molecular mechanisms of neuroendocrine (NE) transformation in lung cancer has been limited by a paucity of pre/posttransformation clinical samples. Detailed genomic, epigenomic, transcriptomic, and protein characterization of combined LUAD/SCLC tumors, as well as pre/posttransformation samples, supports that NE transformation is primarily driven by transcriptional reprogramming rather than mutational events. We identify genomic contexts in which NE transformation is favored, including frequent loss of the 3p chromosome arm. We observed enhanced expression of genes involved in the PRC2 complex and PI3K/AKT and NOTCH pathways. Pharmacologic inhibition of the PI3K/AKT pathway delayed tumor growth and NE transformation in an EGFR-mutant patient-derived xenograft model. Our findings define a novel landscape of potential drivers and therapeutic vulnerabilities of NE transformation in lung cancer. Significance: The difficulty in collection of transformation samples has precluded the performance of molecular analyses, and thus little is known about the lineage plasticity mechanisms leading to LUAD-to-SCLC transformation. Here, we describe biological pathways dysregulated upon transformation and identify potential predictors and potential therapeutic vulnerabilities of NE transformation in the lung. See related commentary by Meador and Lovly, p. 2962. This article is highlighted in the In This Issue feature, p. 2945

The eventual development of resistance to single-agent targeted therapies in lung adenocarcinomas (LUAD) is inevitable, and new strategies are needed. We hypothesize that combination therapies aimed at a known driver and a distinct targetable alteration could prolong time on oral targeted therapy. In an analysis of 7636 patients with LUAD who underwent MSK-IMPACT large panel NGS testing, 5.5% (416/7636) harbored MDM2 amplification (MDM2amp), a known mechanism of TP53 inactivation. MDM2amp was over-represented among tumors with alterations in METex14 (34.4%, p Citation Format: Arielle Elkrief, Vladimir Markov, Álvaro Quintanal-Villalonga, Rebecca Caeser, Pawel Sobczuk, Emily Cheng, Alexander Drilon, Gregory J. Riely, William W. Lockwood, Elisa de Stanchina, Charles M. Rudin, Igor Odintsov, Romel Somwar. MDM2 inhibition in combination with MEK inhibition in pre-clinical models of lung adenocarcinomas with MDM2 amplification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6127.

The impact of the intratumoral microbiome on immune checkpoint inhibitor (ICI) efficacy in patients (pts) with non-small cell lung cancer (NSCLC) is unknown. In preclinical studies, the presence of lung intratumoral Escherichia was associated with a proinflammatory tumor microenvironment and decreased metastases within lung tissue. We sought to detect intratumoral bacteria in pts with advanced NSCLC using hybrid capture-based, next generation sequencing (NGS). We studied 849 pts treated with ICI-based therapy who underwent NGS at our center. We extracted unmapped reads from BAM files, and these were queried for bacteria (blastn alignment using the NCBI database). Putative environmental contaminants were subtracted from the analysis using “no template” controls (n=2,539) to exclude possible artifactual false positives. A custom E.Coli fluorescence in situ hybridization (FISH) probe was used to visualize Escherichia within the tumors after co-registration with H&E. In 849 pts, a median of 30 bacterial reads was detected per sample (inter-quartile range (18-85)). Among 68 pts with paired primary/metastatic samples, the bacterial spectra were similar in both sites, suggesting that tumor resident bacteria might travel with cancer cells to distant sites. Antibiotic use within 30 days of tumor sampling was associated with decreased intratumoral bacterial diversity (p=0.023 by Inverse Simpson, p=0.038 by Shannon). Intratumoral Escherichia was associated with better PFS (HR 0.78, 95% CI 0.62-0.98, p=0.036), and OS (HR 0.74, 95% CI 0.58-0.95, p=0.017) in pts treated with single-agent ICI, but not combination Chemo/ICI. In a multivariable model adjusting for prognostic features in NSCLC including PD-L1 tumor proportion score, the presence of intratumoral Escherichia was associated with better PFS (p=0.040) and OS (p=0.045) upon single-agent ICI therapy. Escherichia appeared to be intracellular based on co-registration of FISH staining and serial H&E sections. These findings warrant further investigation of the possible inter-relationships between intratumoral Escherichia, tumor immune micro-environment, and ICI therapeutic outcomes. Citation Format: Arielle Elkrief, Anita S. Bowman, Ayyuce Begum Bektas, Wenfei Kang, Katia Manova-Todorova, Jacklynn V. Egger, Hira Rizvi, Daniel Kelly, Eric Chan, Eric Rosiek, Fan Ning, Gregory J. Riely, Álvaro Quintanal Villalonga, Snjezana Dogan, Umesh Bhanot, Mithat Gonen, Matthew D. Hellmann, Adam J. Schoenfeld, Charles M. Rudin, Marc Ladanyi, Chad M. Vanderbilt. Intratumoral Escherichia is associated with response to single-agent immune checkpoint inhibition in patients with advanced non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5185.

[Simple Summary] The search for prognostic and/or predictive gene signatures of the response to radiotherapy treatment can significantly aid clinical decision making. These signatures can condition the fractionation, the total dose to be administered, and/or the combination of systemic treatments and radiation. The ultimate goal is to achieve better clinical results, as well as to minimize the adverse effects associated with current cancer therapies. To this end, we analyzed the intrinsic radiosensitivity of 15 NSCLC lines and found the differences in gene expression levels between radiosensitive and radioresistant lines, resulting in a potentially applicable six-gene signature in NSCLC patients. The six-gene signature had the ability to predict overall survival and progression-free survival (PFS), which could translate into a prediction of the response to the cancer treatment received., [Abstract] Non-small-cell lung cancer (NSCLC) is the leading cause of cancer death worldwide, generating an enormous economic and social impact that has not stopped growing in recent years. Cancer treatment for this neoplasm usually includes surgery, chemotherapy, molecular targeted treatments, and ionizing radiation. The prognosis in terms of overall survival (OS) and the disparate therapeutic responses among patients can be explained, to a great extent, by the existence of widely heterogeneous molecular profiles. The main objective of this study was to identify prognostic and predictive gene signatures of response to cancer treatment involving radiotherapy, which could help in making therapeutic decisions in patients with NSCLC. To achieve this, we took as a reference the differential gene expression pattern among commercial cell lines, differentiated by their response profile to ionizing radiation (radiosensitive versus radioresistant lines), and extrapolated these results to a cohort of 107 patients with NSCLC who had received radiotherapy (among other therapies). We obtained a six-gene signature (APOBEC3B, GOLM1, FAM117A, KCNQ1OT1, PCDHB2, and USP43) with the ability to predict overall survival and progression-free survival (PFS), which could translate into a prediction of the response to the cancer treatment received. Patients who had an unfavorable prognostic signature had a median OS of 24.13 months versus 71.47 months for those with a favorable signature, and the median PFS was 12.65 months versus 47.11 months, respectively. We also carried out a univariate analysis of multiple clinical and pathological variables and a bivariate analysis by Cox regression without any factors that substantially modified the HR value of the proposed gene signature., This work was supported by grants from the Ministerio de Ciencia, Innovación y Universidades (MCIU) Plan Estatal de I+D+I 2018, a la Agencia Estatal de Investigación (AEI) y al Fondo Europeo de Desarrollo Regional (MCIU/AEI/FEDER, UE): RTI2018-097455-B-I00; grant from AEI-MICIU/FEDER (RED2018-102723-T); from CIBER de Cáncer (CB16/12/00275), co-funded by FEDER from Regional Development European Funds (European Union); from Consejeria de Salud (PI-0397-2017) and Project P18-RT-2501 from 2018 competitive research projects call within the scope of PAIDI 2020 co-financed by the European Regional Development Fund (ERDF) from the Regional Ministry of Economic Transformation, Industry, Knowledge and Universities, Junta de Andalucía. Special thanks to the AECC (Spanish Association of Cancer Research) Founding Ref. GC16173720CARR and Fundacion Eugenio Rodriguez Pascual for supporting this work. E.S.-M. was funded by a fellowship from Junta de Andalucia. S.M.-G. was funded by Fundación AECC.

Crucial transitions in cancer-including tumor initiation, local expansion, metastasis, and therapeutic resistance-involve complex interactions between cells within the dynamic tumor ecosystem. Transformative single-cell genomics technologies and spatial multiplex in situ methods now provide an opportunity to interrogate this complexity at unprecedented resolution. The Human Tumor Atlas Network (HTAN), part of the National Cancer Institute (NCI) Cancer Moonshot Initiative, will establish a clinical, experimental, computational, and organizational framework to generate informative and accessible three-dimensional atlases of cancer transitions for a diverse set of tumor types. This effort complements both ongoing efforts to map healthy organs and previous large-scale cancer genomics approaches focused on bulk sequencing at a single point in time. Generating single-cell, multiparametric, longitudinal atlases and integrating them with clinical outcomes should help identify novel predictive biomarkers and features as well as therapeutically relevant cell types, cell states, and cellular interactions across transitions. The resulting tumor atlases should have a profound impact on our understanding of cancer biology and have the potential to improve cancer detection, prevention, and therapeutic discovery for better precision-medicine treatments of cancer patients and those at risk for cancer.

Lineage plasticity, the ability of cells to transition from one committed developmental pathway to another, has been proposed as a source of intratumoural heterogeneity and of tumour adaptation to an adverse tumour microenvironment including exposure to targeted anticancer treatments. Tumour cell conversion into a different histological subtype has been associated with a loss of dependency on the original oncogenic driver, leading to therapeutic resistance. A well-known pathway of lineage plasticity in cancer — the histological transformation of adenocarcinomas to aggressive neuroendocrine derivatives — was initially described in lung cancers harbouring an EGFR mutation, and was subsequently reported in multiple other adenocarcinomas, including prostate cancer in the presence of antiandrogens. Squamous transformation is a subsequently identified and less well-characterized pathway of adenocarcinoma escape from suppressive anticancer therapy. The increased practice of tumour re-biopsy upon disease progression has increased the recognition of these mechanisms of resistance and has improved our understanding of the underlying biology. In this Review, we provide an overview of the impact of lineage plasticity on cancer progression and therapy resistance, with a focus on neuroendocrine transformation in lung and prostate tumours. We discuss the current understanding of the molecular drivers of this phenomenon, emerging management strategies and open questions in the field. Lineage plasticity is a source of intratumoural heterogeneity and enables tumour adaptation to an adverse tumour microenvironment, eventually leading to therapeutic resistance. The authors of this Review provide an overview of the impact of lineage plasticity on cancer progression and therapy resistance, with a focus on neuroendocrine transformation in lung and prostate tumours, and discuss emerging management strategies and open questions in the field.

SCLC is a highly aggressive neuroendocrine tumor that is characterized by early acquired therapeutic resistance and modest benefit from immune checkpoint blockade (ICB). Repression of the major histocompatibility complex class I (MHC-I) represents a key mechanism driving resistance to T cell-based immunotherapies.We evaluated the role of the lysine-specific demethylase 1 (LSD1) as a determinant of MHC-I expression, functional antigen presentation, and immune activation in SCLC in vitro and in vivo through evaluation of both human SCLC cell lines and immunocompetent mouse models.We found that targeted inhibition of LSD1 in SCLC restores MHC-I cell surface expression and transcriptionally activates genes encoding the antigen presentation pathway. LSD1 inhibition further activates interferon signaling, induces tumor-intrinsic immunogenicity, and sensitizes SCLC cells to MHC-I-restricted T cell cytolysis. Combination of LSD1 inhibitor with ICB augments the antitumor immune response in refractory SCLC models. Together, these data define a role for LSD1 as a potent regulator of MHC-I antigen presentation and provide rationale for combinatory use of LSD1 inhibitors with ICB to improve therapeutic response in SCLC.Epigenetic silencing of MHC-I in SCLC contributes to its poor response to ICB. Our study identifies a previously uncharacterized role for LSD1 as a regulator of MHC-I antigen presentation in SCLC. LSD1 inhibition enables MHC-I-restricted T cell cytolysis, induces immune activation, and augments the antitumor immune response to ICB in SCLC.

Background Lineage plasticity, the ability to transdifferentiate among distinct phenotypic identities, facilitates therapeutic resistance in cancer. In lung adenocarcinomas (LUADs), this phenomenon includes small cell and squamous cell (LUSC) histologic transformation in the context of acquired resistance to targeted inhibition of driver mutations. LUAD-to-LUSC transdifferentiation, occurring in up to 9% of EGFR-mutant patients relapsed on osimertinib, is associated with notably poor prognosis. We hypothesized that multi-parameter profiling of the components of mixed histology (LUAD/LUSC) tumors could provide insight into factors licensing lineage plasticity between these histologies. Methods We performed genomic, epigenomics, transcriptomics and protein analyses of microdissected LUAD and LUSC components from mixed histology tumors, pre-/post-transformation tumors and reference non-transformed LUAD and LUSC samples. We validated our findings through genetic manipulation of preclinical models in vitro and in vivo and performed patient-derived xenograft (PDX) treatments to validate potential therapeutic targets in a LUAD PDX model acquiring LUSC features after osimertinib treatment. Results Our data suggest that LUSC transdifferentiation is primarily driven by transcriptional reprogramming rather than mutational events. We observed consistent relative upregulation of PI3K/AKT, MYC and PRC2 pathway genes. Concurrent activation of PI3K/AKT and MYC induced squamous features in EGFR-mutant LUAD preclinical models. Pharmacologic inhibition of EZH1/2 in combination with osimertinib prevented relapse with squamous-features in an EGFR-mutant patient-derived xenograft model, and inhibition of EZH1/2 or PI3K/AKT signaling re-sensitized resistant squamous-like tumors to osimertinib. Conclusions Our findings provide the first comprehensive molecular characterization of LUSC transdifferentiation, suggesting putative drivers and potential therapeutic targets to constrain or prevent lineage plasticity.

Summary Small cell lung cancer (SCLC) is an aggressive malignancy that includes subtypes defined by differential expression of ASCL1, NEUROD1, and POU2F3 (SCLC-A, -N, and -P, respectively). To define the heterogeneity of tumors and their associated microenvironments across subtypes, we sequenced 155,098 transcriptomes from 21 human biospecimens, including 54,523 SCLC transcriptomes. We observe greater tumor diversity in SCLC than lung adenocarcinoma, driven by canonical, intermediate, and admixed subtypes. We discover a PLCG2-high SCLC phenotype with stem-like, pro-metastatic features that recurs across subtypes and predicts worse overall survival. SCLC exhibits greater immune sequestration and less immune infiltration than lung adenocarcinoma, and SCLC-N shows less immune infiltrate and greater T cell dysfunction than SCLC-A. We identify a profibrotic, immunosuppressive monocyte/macrophage population in SCLC tumors that is particularly associated with the recurrent, PLCG2-high subpopulation.

Paired T cell receptor and RNA single cell sequencing (scTCR/RNA-seq) has allowed for enhanced resolution of clonal T cell dynamics in cancer. Here, we report a scTCR/RNA-seq dataset of 162,062 single T cells from 31 tissue regions, including tumor, adjacent normal tissues, and lymph nodes (LN), from three patients who underwent resections for progressing lung cancers after immune checkpoint blockade (ICB). We found marked regional heterogeneity in tumor persistence that was associated with heterogeneity in CD4 and CD8 T cell phenotypes; regions with persistent cancer cells were enriched for follicular helper CD4 T cells (TFH), regulatory T cells (Treg), and exhausted CD8 T cells. Clonal analysis demonstrated that highly-expanded T cell clones were predominantly of the CD8 subtype, were ubiquitously present across all sampled regions, found in the peripheral circulation, and expressed gene signatures of ‘large’ and ‘dual-expanded’ clones that have been predictive of response to ICB. Longitudinal tracking of CD8 T cell clones in the peripheral blood revealed that the persistence of ubiquitous CD8 T cell clones, as well as phenotypically distinct clones with tumor-reactive features, correlated with systemic tumor control. Finally, tracking CD8 T cell clones across tissues revealed the presence of TCF-1+precursor exhausted CD8 T cells in tumor draining LNs that were clonally linked to expanded exhausted CD8 T cells in tumors. Altogether, this comprehensive scTCR/RNA-seq dataset with regional, longitudinal, and clonal resolution provides fundamental insights into the tissue distribution, persistence, and differentiation trajectories of ICB-responsive T cells that underlie clinical responses to ICB.

Summary This standardized protocol describes the preparation of PCR amplified and purified samples from human cell lines passaged and collected from CRISPR screening. High-quality samples can be used to perform next-generation sequencing (NGS) to uncover changes in sgRNA abundance from the timepoint at which library-transduced cells are selected to the timepoint when the screen is ended. Here, we describe proper calculation methods for library representation and show how to overcome potential issues often encountered by researchers. For complete information on the use and execution of this protocol, please refer to Wohlhieter et al. (2020) .

Lung adenocarcinoma (LUAD), constituting 50% of non-small cell lung cancer, is classically defined by the presence of driver mutations in oncogenes such as KRAS, EGFR, and BRAF. While the development of driver-targeted therapies has significantly improved survival in subsets of patients with LUAD, studies examining tumor sequencing data and clinical outcomes have shown that intra-driver genetic and phenotypic heterogeneity underlie differential patient responses to these therapies. In particular, co-occurring alterations in the genes SMARCA4 (BRG1), STK11 (LKB1), and KEAP1 are predictive of exceptionally poor prognosis and worse overall survival in metastatic LUAD patients. SMARCA4 loss is also a hallmark of undifferentiated, highly chemoresistant NSCLC tumors. While these co-mutations most often appear in KRAS-driven tumors, their association with poor outcomes is maintained regardless of driver status. Studies exploring the molecular features of SMARCA4-deficient and STK11/KEAP1 co-mutant LUAD have yielded translational insights specific to these subsets, establishing a rationale to characterize the unique biology of SMARCA4/STK11/KEAP1 (BLK) triple-mutant LUAD. To this end, we are profiling BLK LUAD through a combination of genomic, transcriptomic, epigenomic, and phenotypic assays in in vitro models. We have generated paired isogenic in vitro models of BLK LUAD via CRISPR-Cas9 knockout. Phenotypic analyses of these cell lines, whose engineered genotypes model varying combinations of SMARCA4, KEAP1, and STK11 loss, have revealed growth rate differences in vitro, and pairwise comparisons of RNA-sequencing in these lines show downregulation of lung differentiation markers and upregulation of metastasis-associated genes concomitant with SMARCA4 loss. In conclusion, we have generated isogenic preclinical models showing molecular and phenotypic features consistent with observations reported in BLK LUADs. Further molecular and functional characterization of these models may reveal mechanistic insights into the biology of this subset of aggressive tumors. Citation Format: Emily Costa, Corrin Wohlheiter, Samuel Tischfield, Alister Funnell, JT Poirier, Álvaro Quintanal Villalonga, Triparna Sen, Charles Rudin. Characterizing SMARCA4/STK11/KEAP1 co-mutant lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 859.

Small cell lung cancer (SCLC) has limited therapeutic options and an exceptionally poor prognosis. Understanding the oncogenic drivers of SCLC may help define novel therapeutic targets. Recurrent genomic rearrangements have been identified in SCLC, most notably an in-frame gene fusion between RLF and MYCL found in up to 7% of the predominant ASCL1-expressing subtype. To explore the role of this fusion in oncogenesis and tumor progression, we used CRISPR/Cas9 somatic editing to generate a Rlf–Mycl-driven mouse model of SCLC. RLF–MYCL fusion accelerated transformation and proliferation of murine SCLC and increased metastatic dissemination and the diversity of metastatic sites. Tumors from the RLF–MYCL genetically engineered mouse model displayed gene expression similarities with human RLF–MYCL SCLC. Together, our studies support RLF–MYCL as the first demonstrated fusion oncogenic driver in SCLC and provide a new preclinical mouse model for the study of this subtype of SCLC. Significance: The biological and therapeutic implications of gene fusions in SCLC, an aggressive metastatic lung cancer, are unknown. Our study investigates the functional significance of the in-frame RLF–MYCL gene fusion by developing a Rlf–Mycl-driven genetically engineered mouse model and defining the impact on tumor growth and metastasis. This article is highlighted in the In This Issue feature, p. 2945

Heat shock protein 90 (HSP90) plays an essential role in lung adenocarcinoma, acting as a key chaperone involved in the correct functioning of numerous highly relevant protein drivers of this disease. To this end, HSP90 inhibitors have emerged as promising therapeutic strategies, even though responses to them have been limited to date. Given the need to maximize treatment efficacy, the objective of this study was to use isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic techniques to identify proteins in human lung adenocarcinoma cell lines whose basal abundances were correlated with response to HSP90 inhibitors (geldanamycin and radicicol derivatives). From the protein profiles identified according to response, the relationship between lactate dehydrogenase B (LDHB) and DNA topoisomerase 1 (TOP1) with respect to sensitivity and resistance, respectively, to geldanamycin derivatives is noteworthy. Likewise, rhotekin (RTKN) and decaprenyl diphosphate synthase subunit 2 (PDSS2) were correlated with sensitivity and resistance to radicicol derivatives. We also identified a relationship between resistance to HSP90 inhibition and the p53 pathway by glucose deprivation. In contrast, arginine biosynthesis was correlated with sensitivity to HSP90 inhibitors. Further study of these outcomes could enable the development of strategies to improve the clinical efficacy of HSP90 inhibition in patients with lung adenocarcinoma.

Small cell lung cancer (SCLC) is an aggressive malignancy that includes subtypes defined by differential expression of ASCL1, NEUROD1, and POU2F3 (SCLC-A, -N, and -P, respectively), which are associated with distinct therapeutic vulnerabilities. To define the heterogeneity of tumors and their associated microenvironments across subtypes, we sequenced 54,523 cellular transcriptomes from 21 human biospecimens. Our single-cell SCLC atlas reveals tumor diversity exceeding lung adenocarcinoma, driven by canonical, intermediate, and admixed subtypes. We discovered a PLCG2-high tumor cell population with stem-like, pro-metastatic features that recurs across subtypes and predicts worse overall survival, and manipulation of PLCG2 expression in cells confirms correlation with key metastatic markers. Treatment and subtype are associated with substantial phenotypic changes in the SCLC immune microenvironment, with greater T-cell dysfunction in SCLC-N than SCLC-A. Moreover, the recurrent, PLCG2-high subclone is associated with exhausted CD8+ T-cells and a pro-fibrotic, immunosuppressive monocyte/macrophage population, suggesting possible tumor-immune coordination to promote metastasis.

SUMMARY Concurrent loss-of-function mutations in STK11 and KEAP1 in lung adenocarcinoma (LUAD) are associated with aggressive tumor growth, resistance to available therapies, and early death. We investigated the effects of coordinate STK11 and KEAP1 loss by comparing co-mutant with single mutant and wild-type isogenic counterparts in multiple LUAD models. STK11/KEAP1 co-mutation results in significantly elevated expression of ferroptosis-protective genes, including SCD and AKR1C1/2/3, and resistance to pharmacologically induced ferroptosis. CRISPR screening further nominates SCD (SCD1) as selectively essential in STK11/KEAP1 co-mutant LUAD. Genetic and pharmacological inhibition of SCD1 confirms the essentiality of this gene and augments the effects of ferroptosis induction by erastin and RSL3. Together these data identify SCD1 as a selective vulnerability and a promising candidate for targeted drug development in STK11/KEAP1 co-mutant LUAD., Graphical Abstract, In Brief Wohlhieter et al. explore the global changes in gene expression and oncogenic signaling pathways driven by concurrent loss of function in two tumor suppressor genes, STK11 and KEAP1. They identify a molecular vulnerability, in which co-mutant cells depend on ferroptosis protective mechanisms for survival, and highlight SCD1 as an essential gene and promising drug target.

Human clinical samples pose a challenge for single-cell RNA-seq (scRNA-seq) and single-nucleus ATAC-seq (snATAC-seq) analysis, due to their heterogeneity in cell type composition and degree of degradation or necrosis. Moreover, although some tissues can be sampled by surgical resection, most biospecimens are derived from core needle biopsies or fine needle aspirates, and must be allocated to pressing needs such as pathological analysis, thereby severely limiting the number of cells available for analysis. We have developed a protocol for obtaining robust, high-quality single-cell sequencing data from human biospecimens from a variety of biopsy types, enabling greater access to clinical cohorts. A critical factor is to limit ischemic time and transport to the lab to under an hour, and to restrict subsequent processing time to under 3 hours. This protocol uses a commercial tissue disruptor for dissociation. It was optimized on diverse human lung tumor samples, including pleural effusions, but is widely applicable to normal and diseased human clinical tissues from different organ sites.

[Background] Fibroblast growth factor receptor (FGFR)1 and FGFR4 have been associated with tumorigenesis in a variety of tumour types. As a therapeutic approach, their inhibition has been attempted in different types of malignancies, including lung cancer, and was initially focused on FGFR1-amplified tumours, though with limited success., [Methods] In vitro and in vivo functional assessments of the oncogenic potential of downregulated/overexpressed genes in isogenic cell lines were performed, as well as inhibitor efficacy tests in vitro and in vivo in patient-derived xenografts (PDXs). mRNA was extracted from FFPE non-small cell lung cancer samples to determine the prognostic potential of the genes under study., [Findings] We provide in vitro and in vivo evidence showing that expression of the adhesion molecule N-cadherin is key for the oncogenic role of FGFR1/4 in non-small cell lung cancer. According to this, assessment of the expression of genes in different lung cancer patient cohorts showed that FGFR1 or FGFR4 expression alone showed no prognostic potential, and that only co-expression of FGFR1 and/or FGFR4 with N-cadherin inferred a poorer outcome. Treatment of high-FGFR1 and/or FGFR4-expressing lung cancer cell lines and patient-derived xenografts with selective FGFR inhibitors showed high efficacy, but only in models with high FGFR1/4 and N-cadherin expression., [Interpretation] Our data show that the determination of the expression of FGFR1 or FGFR4 alone is not sufficient to predict anti-FGFR therapy efficacy; complementary determination of N-cadherin expression may further optimise patient selection for this therapeutic strategy., This work was funded by the Community of Madrid, the ISCIII co-funded by FEDER from Regional Development European Funds (European Union), the Spanish Ministry of Economy and Competitiveness, the Mutua Madrileña Foundation, the Ministry of Health and Social Welfare of Junta de Andalucía, the AECC scientific foundation and the Spanish Ministry of Education, Culture and Sport.

[Background] Lung cancer remains the most common cause of cancer-related death, with a 5-year survival rate of only 18%. In recent years, the development of targeted pharmacological agents and immunotherapies has substantially increased the survival of a subset of patients. However, most patients lack such efficacious therapy and are, thus, treated with classical chemotherapy with poor clinical outcomes. Therefore, novel therapeutic strategies are urgently needed. In recent years, the development of epigenetic assays and their application to cancer research have highlighted the relevance of epigenetic regulation in the initiation, development, progression and treatment of lung cancer., [Conclusions] A variety of epigenetic modifications do occur at different steps of lung cancer development, some of which are key to tumor progression. The rise of cutting-edge technologies such as single cell epigenomics is, and will continue to be, crucial for uncovering epigenetic events at a single cell resolution, leading to a better understanding of the biology underlying lung cancer development and to the design of novel therapeutic options. This approach has already led to the development of strategies involving single agents or combined agents targeting epigenetic modifiers, currently in clinical trials. Here, we will discuss the epigenetics of every step of lung cancer development, as well as the translation of these findings into clinical applications., SMP was supported by the Consejería de Salud y Bienestar Social of Junta de Andalucía through the “‘Nicolás Monardes’ program [C-0040-2016] and ISCIII (PI17/00033) and cofounder by FEDER from Regional Development European Funds (European Union).”

[Objectives] Lung adenocarcinoma accounts for approximately half of lung cancer cases. Twenty to 50% of tumors of this type harbor mutations affecting epidermal growth factor receptor (EGFR) expression or activity, which can be therapeutically targeted. EGFR inhibitors in this context exhibit high efficacy and are currently used in the clinical setting. However, not all adenocarcinomas harboring EGFR mutations respond to therapy, so predictive biomarkers of therapeutic outcomes, as well as novel therapies sensitizing these tumors to EGFR inhibition, are needed., [Materials and methods] We performed in vitro gene overexpression/silencing and tumorigenic surrogate assays, as well as in vitro and in vivo combination treatments with Fibroblast Growth Factor Receptor (FGFR)/EGFR inhibitors. At the clinical level, we determined FGFR4 expression levels in tumors from patients treated with EGFR inhibitors and correlated these with treatment response., [Results] We describe a cooperative interaction between EGFR and FGFR4, which results in their reciprocal activation with pro-oncogenic consequences in vitro and in vivo. This cooperation is independent of EGFR activating mutations and increases resistance to different EGFR inhibitors. At the therapeutic level, we provide evidence of the synergistic effects of the combination of EGFR and FGFR inhibitors in high FGFR4-expressing, EGFR-activated tumors in vitro and in vivo. Correlated with these results, we found that patients treated with EGFR inhibitors relapse earlier when their tumors exhibit high FGFR4 expression., [Conclusions] We propose a novel predictive biomarker for EGFR-targeted therapy, and a highly efficacious combinatory therapeutic strategy to treat EGFR-dependent; this may may extend the use of appropriate inhibitors beyond EGFR-mutated adenocarcinoma patients., L.P.A. was funded by the Comunidad de Madrid, CAM, (B2017/BMD3884), ISCIII (PI14/01964, PIE15/00076, PI17/00778 and DTS17/00089) and CIBERONC (CD16/12/00442), and co-funded by FEDER from Regional Development European Funds (European Union). I.F. is funded by the AECC (AIO2015) and Consejería de Igualdad, Salud y Políticas Sociales de la Junta de Andalucía (PI-0029-2013) and ISCIII (PI16/01311), and co-funded by FEDER from Regional Development European Funds (European Union). AC was supported by grants from the Spanish Ministry of Economy and Competitiveness Plan Estatal de I + D+I 2013–2016, ISCIII (PI15/00045) and CIBERONC (CD16/12/00275), and co-funded by FEDER from Regional Development European Funds (European Union). S.M.P. is funded by the Consejería de Salud y Bienestar Social (PI-0046-2012), the Fundación Mutua Madrileña (2014) and ISCIII (PI17/00033). A.Q is funded by the ISCIII (FI12/00429). L.O. is funded by the Ministerio de Educación, Cultura y Deporte (FPU13/02595).

Introduction EGFR-mutant lung cancers are clinically and genomically heterogeneous with concurrent RB transcriptional corepressor 1 (RB1)/tumor protein p53 (TP53) alterations identifying a subset at increased risk for small cell transformation. The genomic alterations that induce lineage plasticity are unknown. Methods Patients with EGFR/RB1/TP53-mutant lung cancers, identified by next-generation sequencing from 2014 to 2018, were compared to patients with untreated, metastatic EGFR-mutant lung cancers without both RB1 and TP53 alterations. Time to EGFR–tyrosine kinase inhibitor discontinuation, overall survival, SCLC transformation rate, and genomic alterations were evaluated. Results Patients with EGFR/RB1/TP53-mutant lung cancers represented 5% (43 of 863) of EGFR-mutant lung cancers but were uniquely at risk for transformation (7 of 39, 18%), with no transformations in EGFR-mutant lung cancers without baseline TP53 and RB1 alterations. Irrespective of transformation, patients with EGFR/TP53/RB1-mutant lung cancers had a shorter time to discontinuation than EGFR/TP53- and EGFR-mutant –only cancers (9.5 versus 12.3 versus 36.6 months, respectively, p = 2 × 10-9). The triple-mutant population had a higher incidence of whole-genome doubling compared to NSCLC and SCLC at large (80% versus 34%, p Conclusions EGFR/TP53/RB1-mutant lung cancers are at unique risk of histologic transformation, with 25% presenting with de novo SCLC or eventual small cell transformation. Triple-mutant lung cancers are enriched in whole-genome doubling and Activation-induced cytidine deaminase/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like hypermutation which may represent early genomic determinants of lineage plasticity.

Patient-derived xenografts (PDXs) constitute a powerful set of preclinical models for in vivo cancer research, reflecting the spectrum of genomic alterations and therapeutic liabilities of human cancers1-4. In contrast to either cancer cell lines or genetically engineered mouse models, the utility of PDXs has been limited by the inability to perform targeted genome editing of these tumors. To address this limitation, we have generated a lentiviral platform for CRISPR-Cas9 editing of PDXs using a tightly regulated, inducible Cas9 vector that does not require in vitro culture for selection of transduced cells. We demonstrate the utility of this platform in PDXs (1) to analyze genetic dependencies by targeted gene disruption and (2) to analyze mechanisms of acquired drug resistance by site-specific gene editing using templated homology-directed repair. This flexible system has broad application to other explant models and substantially augments the utility of PDXs as genetically programmable models of human cancer.

Introduction: There is substantial evidence for the onco- genic effects of fi broblast growth factor receptor 1 (FGFR1) in many types of cancer, including lung cancer, but the role of this receptor has not been addressed speci fi cally in lung adenocarcinoma. Methods: We performed FGFR1 and EGFR overexpression and co-overexpression assays in adenocarcinoma and in inmortalized lung cell lines, and we also carried out surrogateandinteractionassays.Weperformedmono- therapy and combination EGFR /FGFR inhibitor sensitivity assays in vitro and in vivo in cell line – and patient- derived xenografts. We determined FGFR1 mRNA expression in a cohort of patients with anti – EGFR ther- apy – treated adenocarcinoma. Results: We have reported a cooperative interaction between FGFR1 and EGFR in this context, resulting in increased EGFR activation and oncogenic signaling. We have provided in vitro and in vivo evidence indicating that FGFR1 expression in- creases tumorigenicity in cells with high EGFR activation in EGFR-mutated and EGFR wild-type models. At the clinical level, we have shown that high FGFR1 expression levels pre- dict higher resistance to erlotinib or ge fi tinib in a cohort of patients with tyrosine kinase inhibitor – treated EGFR-mutated and EGFR wild-type lung adenocarcinoma. Dual EGFR and FGFR inhibition in FGFR1-over expressing, EGFR-activated models shows synergistic effects on tumor growth in vitro and in cell line – and patient-derived xenografts, suggesting that patients with tumors bearing these characteristics may bene fi t from combined EGFR/FGFR inhibition. Conclusion: These results support the extended the use of EGFR inhibitors beyond monotherapy in the EGFR-mutated adenocarcinoma setting in combination with FGFR in- hibitors for selected patients with increased FGFR1 over- expression and EGFR activation. ISCIII PI14/01964 PIE15/00076 PI17/00778 DTS17/00089 PI15/00045 PI17/00033 PI16/01311 FI12/00429 CIBERONC CD16/12/00442 FEDER CD16/12/00442 PI16/01311 Spanish Ministry of Economy and Competitiveness PI15/00045 Ministry of Health and Social Welfare of Junta de Andalucía PI-0046-2012 C-0040-2016 Ministry of Equality, Health and Social Policies of the Junta de Andalucía PI- 0029-2013 Comunidad de Madrid B2017/BMD3884 Ministry of Education, Culture and Sports FPU13/02595

[Introduction] FGFR4 is a tyrosine kinase receptor which, under physiological conditions, is activated upon ligand binding in a highly regulated manner. This triggers downstream signaling related to proliferation and apoptosis resistance as well as other physiological processes. Many molecular alterations of the receptor and its ligands, specially FGF19, have been reported in several types of cancer, with special relevance in hepatocellular carcinoma. In addition, these have also been detected in other solid malignancies, including lung, breast, or colon cancer, among others., [Areas covered] This review covers patent literature on specific FGFR4 inhibitors and their applications, published from 2007 to June 2018., [Expert opinion] FGFR4 inhibition has gained relevance in oncology. A considerable number of patents disclosing different approaches to inhibit this receptor have been reported, displaying promising preclinical results for different cancer models. Currently, the safety and preliminary efficacy of several small molecule inhibitors targeting FGFR4 are under early phase clinical assessment, mainly in hepatocellular carcinoma patients. If positive results are derived from these trials, they will open the door for the application of FGFR4 small molecule inhibitors to a wide population of tumors of different types that harbor FGFR4-FGF19 signaling dysregulation., [Trial registration] ClinicalTrials.gov identifier: NCT02325739., [Trial registration] ClinicalTrials.gov identifier: NCT02834780., [Trial registration] ClinicalTrials.gov identifier: NCT03144661., [Trial registration] ClinicalTrials.gov identifier: NCT02508467., L Paz Ares was supported by ISCIII (PI14/01964, PIE15/00076, PI17/00778 and DTS17/00089) and CIBERONC (CD16/12/00442), and co-funded by FEDER from Regional Development European Funds (European Union). L Paz Ares also reports personal fees from Roche, Lilly, MSD, BMS, Astra Zeneca, Boehringer Ing., Pfizer, Takeda, Novartis, Merck Serono and Amgem, outside the submitted work. In addition, L Paz Ares has patent P201730928 and patent PCT/ES2018/070502 pending. I Ferrer was supported by AECC (AIO2015) and Consejería de Igualdad, Salud y Políticas Sociales de la Junta de Andalucía (PI-0029-2013) and ISCIII (PI16/01311) and cofunded by FEDER from Regional Development European Funds (European Union). Also, I Ferrer has patent P201730928 and patent PCT/ES2018/070502 pending. S Molina-Pinelo was supported by the Consejería de Salud y Bienestar Social of Junta de Andalucía through the ‘“Nicolás Monardes”’ program [C-0040-2016] and ISCIII (PI17/00033) and co-funded by FEDER from Regional Development European Funds (European Union). Also, S Molina-Pinelo has patent P201730928 and patent PCT/ES2018/070502 pending.

Heat shock protein 90 (HSP90) is an important chaperone in lung adenocarcinoma, with relevant protein drivers such as EGFR (epidermal growth factor receptor) and EML4-ALK (echinoderm microtubule-associated protein-like protein4 fused to anaplastic lymphoma kinase) depending on it for their correct function, therefore HSP90 inhibitors show promise as potential treatments for lung adenocarcinoma. To study responses to its inhibition, HSP90 was pharmacologically interrupted by geldanamycin and resorcinol derivatives or with combined inhibition of HSP90 plus HSP70 in lung adenocarcinoma cell lines. Two-dimensional electrophoresis was performed to identify proteomic profiles associated with inhibition which will help to understand the biological basis for the responses. HSP90 inhibition resulted in altered protein profiles that differed according the treatment condition studied. Results revealed 254 differentially expressed proteins after treatments, among which, eukaryotic translation initiation factor3 subunit I (eIF3i) and citrate synthase demonstrated their potential role as response biomarkers. The differentially expressed proteins also enabled signalling pathways involved in responses to be identified; these included apoptosis, serine-glycine biosynthesis and tricarboxylic acid cycle. The proteomic profiles identified here contribute to an improved understanding of HSP90 inhibition and open possibilities for the detection of potential response biomarkers which will be essential to maximize treatment efficacy in lung adenocarcinoma., L.P.A. was funded by the Comunidad de Madrid, CAM, (B2017/BMD3884), ISCIII (PIE15/00076, PI17/00778 and DTS17/00089) and CIBERONC (CB16/12/00442), and co-funded by FEDER from Regional Development European Funds (European Union). S.M.P. is funded by the Fundación Mutua Madrileña (2014) Ministry of Health and Social Welfare of Junta de Andalucía (PI-0046-2012, Nicolas Monardes Program C-0040-2016), ISCIII (PI17/00033), and co-funded by FEDER from Regional Development European Funds (European Union). I.F. is funded by the AECC (AIO2015) and ISCIII (PI16/01311), and co-funded by FEDER from Regional Development European Funds (European Union). AC was funded by grants from the Spanish Ministry of Economy and Competitiveness Plan Estatal de I+D+I 2018 co-funded by FEDER: RTI2018-097455-B-I00; CIBER de Cáncer (CB16/12/00275), co-funded by FEDER from Regional Development European Funds. Especial thanks to the Fundación AECC. L.O. is funded by the Ministerio de Educación, Cultura y Deporte (FPU13/02595).

8509 Background: Small cell lung cancer (SCLC) is an aggressive malignancy that includes subtypes defined by differential expression of ASCL1, NEUROD1, and POU2F3 (SCLC-A, -N, and -P, respectively), which are associated with distinct therapeutic vulnerabilities. The emerging consensus on SCLC subtypes has led to new questions, such as whether subtypes are associated with different disease stages, metastatic potential, or immune microenvironments; whether there is plasticity between subtypes; and whether novel SCLC phenotypes exist. Single cell RNA sequencing (scRNA-seq) offers a unique opportunity to address these questions by dissecting intratumoral transcriptional heterogeneity and the surrounding tumor microenvironment (TME). However, efforts to apply this technology to human SCLC tumors have been limited, as these tumors are infrequently resected. Methods: We have optimized protocols to process both surgical resections and biopsies to construct the first single-cell atlas of SCLC patient tumors (N = 21), with comparative lung adenocarcinoma (LUAD) and normal lung data. We leverage computational methods including diffusion maps and non-negative matrix factorization to perform a deep annotation of SCLC phenotypes and the surrounding immune TME. We perform validation experiments using flow cytometry, Vectra, and immunohistochemistry in independent SCLC cohorts, as well as genetic manipulation in preclinical SCLC models. Results: Our data reveals substantial transcriptional heterogeneity in SCLC both within and across tumors and confirms a pro-metastatic gene program in SCLC-N subtype characterized by epithelial-mesenchymal transformation and axonogenesis. Beyond known subtypes, we discover a PLCG2-high tumor cell population with stem-like, pro-metastatic features that recurs across subtypes and predicts significantly worse overall survival. Manipulation of PLCG2 expression in cells confirms correlation with key metastatic markers. Treatment and subtype are associated with substantial phenotypic changes in the SCLC immune microenvironment, with greater T-cell dysfunction in SCLC-N than SCLC-A. Moreover, the recurrent, PLCG2-high subclone is associated with exhausted CD8+ T-cells and a pro-fibrotic, immunosuppressive monocyte/macrophage population, suggesting possible tumor-immune coordination to promote metastasis. Conclusions: This atlas of SCLC illustrates how canonical subtypes and a novel PLCG2-high recurrent tumor subclone enlist diverse gene programs to create tumor heterogeneity and facilitate metastasis in a profoundly immunosuppressed TME. Our dataset provides further insight into tumor and immune biology in SCLC at single-cell resolution, with potential implications for design of novel targeted therapies and immunotherapeutic approaches.

BACKGROUND: The high incidence and mortality of lung tumours is a major health problem. Therefore, the identification both of biomarkers predicting efficacy for therapies in use and of novel efficacious therapeutic agents is crucial to increase patient survival. MAP17 (PDZK1IP1) is a small membrane-bound protein whose upregulation is reported as a common feature in tumours from diverse histological origins. Furthermore, MAP17 is correlated with tumour progression. METHODS: We assessed the expression of MAP17 in preclinical models, including cell lines and patient-derived xenografts (PDXs), assessing its correlation with sensitivity to different standard-of-care drugs in lung adenocarcinoma, as well as novel drugs. At the clinical level, we subsequently correlated MAP17 expression in human tumours with patient response to these therapies. RESULTS: We show that MAP17 expression is induced during lung tumourigenesis, particularly in lung adenocarcinomas, and provide in vitro and in vivo evidence that MAP17 levels predict sensitivity to therapies currently under clinical use in adenocarcinoma tumours, including cisplatin, carboplatin and EGFR inhibitors. In addition, we show that MAP17 expression predicts proteasome inhibitor efficacy in this context and that bortezomib, an FDA-approved drug, may be a novel therapeutic approach for MAP17-overexpressing lung adenocarcinomas. CONCLUSIONS: Our results indicate a potential prognostic role for MAP17 in lung tumours, with particular relevance in lung adenocarcinomas, and highlight the predictive pot0065ntial of this membrane-associated protein for platinum-based therapy and EGFR inhibitor efficacy. Furthermore, we propose bortezomib treatment as a novel and efficacious therapy for lung adenocarcinomas exhibiting high MAP17 expression. The authors thank the donors, the HUVR-IBiS Biobank (Andalusian Public Health System Biobank and ISCIII-Red de Biobancos PT13/0010/0056), and the Hospital 12 de Octubre Biobank for the human specimens used in this study. Sí

Lung tumors represent a major health problem. In early stage NSCLC tumors, surgical resection is the preferred treatment, but 30-55% of patients will relapse within 5 years after surgery. Thus, the identification of prognostic biomarkers in early stage NSCLC patients, especially those which are therapeutically addressable, is crucial to enhance survival of these patients. We determined the immunohistochemistry expression of key proteins involved in tumorigenesis and oncogenic signaling, p53, EGFR, pAKT and pERK, and correlated their expression level to clinicopathological characteristics and patient outcome. We found EGFR expression is higher in the squamous cell carcinomas than in adenocarcinomas (p=0.043), and that nuclear p53 staining correlated with lower differentiated squamous tumors (p=0.034). Regarding the prognostic potential of the expression of these proteins, high pERK levels proved to be an independent prognostic factor for overall (p, The authors thank the donors and the HUVR-IBiS Biobank (Andalusian Public Health System Biobank and ISCIII-Red de Biobancos PT13/0010/0056) for the human specimens used in this study.

The scaffold protein Spinophilin (Spinophilin, PPP1R9B) is one of the regulatory subunits of phosphatase-1 (PP1), directing it to distinct subcellular locations and targets. The loss of Spinophilin reduces PP1 targeting to pRb, thereby maintaining higher levels of phosphorylated pRb. Spinophilin is absent or reduced in approximately 40% of human lung tumors, correlating with the malignant grade. However, little is known about the relevance of the coordinated activity or presence of Spinophilin and its reported catalytic partners in the prognosis of lung cancer. In the present work, we show that the downregulation of Spinophilin, either by protein or mRNA, is related to a worse prognosis in lung tumors. This effect is more relevant in squamous cell carcinoma, SCC, than in adenocarcinoma. Downregulation of Spinophilin is related to a decrease in the levels of its partners PPP1CA/B/C, the catalytic subunits of PP1. A decrease in these subunits is also related to prognosis in SCC and, in combination with a decrease in Spinophilin, are markers of a poor prognosis in these tumors. The analysis of the genes that correlate to Spinophilin in lung tumors showed clear enrichment in ATP biosynthesis and protein degradation GO pathways. The analysis of the response to several common and pathway-related drugs indicates a direct correlation between the Spinophilin/PPP1Cs ratio and the response to oxaliplatin and bortezomib. This finding indicates that this ratio may be a good predictive biomarker for the activity of the drugs in these tumors with a poor prognosis., This work was funded by grants from the Spanish Ministry of Economy and Competitivity, Plan Estatal de I+D+I 2013-2016, ISCIII (Fis: PI15/00045) and CIBER de Cáncer (CB16/12/00275, CB16/12/00443, CB16/12/00442), co-funded by FEDER from Regional Development European Funds (European Union), Consejeria de Ciencia e Innovacion (CTS-1848) and Consejeria de Salud of the Junta de Andalucia (PI-0096-2014). Especial thanks to the AECC Foundation for also supporting this work. This work has also been made possible by the Fundacion BBVA.

The FGFR4-388Arg variant has been related to poor prognosis in several types of cancer, including lung cancer. The mechanism underlying this association has not been addressed in detail in patients with this pathology. Here, we report that this FGFR4 variant induces MAPK and STAT3 activation and causes pro-oncogenic effects in NSCLC in vitro and in vivo. This variant induces the expression of EMT-related genes, such as N-cadherin, vimentin, Snail1 and Twist1. Indeed, the induction of N-cadherin protein expression by this variant is essential for its pro-tumorigenic role. The presence of the FGFR4-388Arg variant correlates with higher N-cadherin expression levels in clinical NSCLC samples and with poorer outcome in patients with FGFR expression. These results support the prognostic role of this FGFR variant in lung cancer and show that these effects may be mediated by the induction of N-cadherin expression and an EMT phenotype., L.P.A. was funded by ISCIII (PI14/01964 and PIE15/00076), CIBER (CB16/12/00442) and RTICC (R12/0036/0028) and co-funded by European Union (ERDF/ESF, “Investing in your future”). The laboratory of A.C. was supported by grants from the Spanish Ministry of Economy and Competitiveness, PN I+D+I 2008-2011, PE I+D+I 2013-2016, ISCIII (PI15/00045 and CB16/12/00275), Consejeria de Ciencia e Innovacion (CTS-1848) and Consejeria de Salud of the Junta de Andalucia (PI-0096-2014). S.M.P. is funded by Consejería de Salud y Bienestar Social (PI-0046-2012), ISCIII (PI17/00033) and co-funded by European Union (ERDF/ESF, “Investing in your future”), and Fundación Mutua Madrileña (2014). I.F. is funded by AECC (AIO2015) and Consejería de Igualdad, Salud y Políticas Sociales de la Junta de Andalucía (PI-0029-2013) and FIS (PI16/01311). A.Q. is funded by ISCIII (FI12/00429). L.O. is funded by Ministerio de Educación, Cultura y Deporte (FPU13/02595).

Lung cancer is a heterogeneous disease responsible for the most cases of cancer-related deaths. The majority of patients are clinically diagnosed at advanced stages, with a poor survival rate. For this reason, the identification of oncodrivers and novel biomarkers is decisive for the future clinical management of this pathology. The rise of high throughput technologies popularly referred to as “omics” has accelerated the discovery of new biomarkers and drivers for this pathology. Within them, tyrosine kinase receptors (TKRs) have proven to be of importance as diagnostic, prognostic, and predictive tools and, due to their molecular nature, as therapeutic targets. Along this review, the role of TKRs in the different lung cancer histologies, research on improvement of anti-TKR therapy, and the current approaches to manage anti-TKR resistance will be discussed.

Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) are smoking-related diseases, with the presence of COPD itself increasing the risk for development of LC, probably owing to underlying inflammation. LC is typically detected at late stages of the disease and carries a poor prognosis. There is an unmet need for methods to facilitate the early detection of LC in high-risk subjects such as smokers.The expression of inflammatory proteins in bronchoalveolar lavage fluid (BALF) samples was studied by antibody arrays in a prospective cohort of 60 smokers of more than 30 pack-years divided into four groups (control, patients with LC, patients with COPD, and patients with LC plus COPD). Relevant biomarkers were validated by Western blot. Additional validation with enzyme-linked immunosorbent assay (ELISA) was carried out on two independent controlled cohorts of 139 patients (control, patients with LC, patients with COPD, and patients with LC plus COPD) and 160 patients (control and patients with LC of all histological types).A total of 16 differentially expressed proteins in samples from patients with LC, COPD, and LC plus COPD were identified by antibody arrays and validated by Western blot and ELISA. C-C motif chemokine ligand 1 (CCL-1) and interleukin-11 (IL)-11 were selectively expressed in samples from patients with adenocarcinoma with or without COPD (p0.005). These proteins exhibited a remarkable diagnostic performance for lung adenocarcinoma in an independent cohort of 139 patients. Receiver operating characteristic curves showed that the optimum diagnostic cutoff value for IL-11 was 42 pg/mL (area under the curve = 0.93 [95% confidence interval: 0.896-0.975], sensitivity 90%, specificity 86%), whereas for CCL-1 it was 39.5 pg/mL (0.83 [95% confidence interval: 0.749-0.902], sensitivity 83%, and specificity 74%). Further validation of the ELISA biomarkers at the aforementioned cutoffs was performed in an additional cohort of 160 patients (20 controls, 66 patients with LC, and 74 patients with LC plus COPD). There was a significant correlation between BALF levels of IL-11 and CCL-1 (rIL-11 and CCL-1 are highly specific biomarkers with great accuracy for the diagnosis of lung adenocarcinoma in BALF specimens. Further study of these proteins as markers for the early diagnosis and screening of plasma and other biological materials is warranted.

Lung cancer is a heterogeneous disease responsible for the most cases of cancer-related deaths. The majority of patients are clinically diagnosed at advanced stages, with a poor survival rate. For this reason, the identification of oncodrivers and novel biomarkers is decisive for the future clinical management of this pathology. The rise of high throughput technologies popularly referred to as “omics” has accelerated the discovery of new biomarkers and drivers for this pathology. Within them, tyrosine kinase receptors (TKRs) have proven to be of importance as diagnostic, prognostic, and predictive tools and, due to their molecular nature, as therapeutic targets. Along this review, the role of TKRs in the different lung cancer histologies, research on improvement of anti-TKR therapy, and the current approaches to manage anti-TKR resistance will be discussed.

Fibroblast growth factor receptor (FGFR)1 has been associated with tumorigenesis in a variety of tumors, including lung cancer. FGFR1 amplification is detected in up to 20% of lung squamous cell carcinomas, and was initially related to tumorigenesis and to response to FGFR inhibitors in preclinical models of this pathology. These data encouraged the establishment of FGFR1 amplification as the main eligibility criterion for inclusion of patients in FGFR inhibitors clinical trials. However, the use of FGFR inhibitors in FGFR1-amplified tumors has shown limited success, with only 5-10% of selected patients showing partial response, suggesting that this genomic aberration may not be a good predictive biomarker for the efficacy of these inhibitors. In this work, we provide in vitro and in vivo data showing that the oncogenic effects of FGFR1 expression depend on the expression of the adhesion molecule N-cadherin in non-small cell lung cancer (NSCLC). In line with these results, FGFR1 expression correlates with poorer prognosis only in tumors with high N-cadherin levels in two independent NSCLC patient cohorts. We observed that high FGFR1 expression alone is not sufficient to predict FGFR inhibition efficacy in lung cancer cell lines and patient-derived xenografts, with only high FGFR1- and high N-cadherin-expressing models responding to selective FGFR inhibitors. Altogether, our data show that the determination of the expression of FGFR1 alone is not sufficient to predict FGFR inhibition efficacy. The co-determination of N-cadherin expression may optimize patient selection for this therapeutic strategy. Citation Format: Álvaro Quintanal-Villalonga, Irene Ferrer, Ángela Marrugal, Laura Ojeda-Márquez, Jon Zugazagoita, Laura García-Redondo, Fernando López-Ríos, Luis Montuenga, Sonia Molina-Pinelo, Sonia Molina-Pinelo, Amancio Carnero, Luis Paz-Ares. Novel predictor of FGFR1 inhibition efficacy in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2589.