Academia and society should join forces to make anti-cancer treatments more affordable

Discovery research is the starting point for the development of more effective anti-cancer treatments. It requires an interdisciplinary research environment with first-class infrastructural support in which curiosity-driven research can lead to new concepts for treating cancer. Translating such research findings to clinical practice requires complementary skills and infrastructures, including high-quality clinical facilities, access to patient cohorts and participation of pharma. This complex ecosystem has yielded many new but also "me too" treatment regimens, especially in immuno-oncology resulting in an extremely high pricing of anti-cancer agents. The costs of antibodies, vaccines, and cell therapies charged by pharma stand out although the concepts and methodologies have been largely developed in academia, financed from public funds. Comprehensive Cancer Centres (CCCs) covering a coherent stretch of the cancer research continuum are well-positioned to make these personalized treatments more affordable, but this will require restructuring of the way the translational cancer research continuum is funded.

Transforming lung cancer types

Lung cancer cells can escape targeted therapy by switching oncogenic drivers and cell identity.

Strategies to decrease inequalities in cancer therapeutics, care and prevention: Proceedings on a conference organized by the Pontifical Academy of Sciences and the European Academy of Cancer Sciences, Vatican City, February 23-24, 2023

Analyses of inequalities related to prevention and cancer therapeutics/care show disparities between countries with different economic standing, and within countries with high Gross Domestic Product. The development of basic technological and biological research provides clinical and prevention opportunities that make their implementation into healthcare systems more complex, mainly due to the growth of Personalized/Precision Cancer Medicine (PCM). Initiatives like the USA-Cancer Moonshot and the EU-Mission on Cancer and Europe's Beating Cancer Plan are initiated to boost cancer prevention and therapeutics/care innovation and to mitigate present inequalities. The conference organized by the Pontifical Academy of Sciences in collaboration with the European Academy of Cancer Sciences discussed the inequality problem, dependent on the economic status of a country, the increasing demands for infrastructure supportive of innovative research and its implementation in healthcare and prevention programs. Establishing translational research defined as a coherent cancer research continuum is still a challenge. Research has to cover the entire continuum from basic to outcomes research for clinical and prevention modalities. Comprehensive Cancer Centres (CCCs) are of critical importance for integrating research innovations to preclinical and clinical research, as for ensuring state-of-the-art patient care within healthcare systems. International collaborative networks between CCCs are necessary to reach the critical mass of infrastructures and patients for PCM research, and for introducing prevention modalities and new treatments effectively. Outcomes and health economics research are required to assess the cost-effectiveness of new interventions, currently a missing element in the research portfolio. Data sharing and critical mass are essential for innovative research to develop PCM. Despite advances in cancer research, cancer incidence and prevalence is growing. Making cancer research infrastructures accessible for all patients, considering the increasing inequalities, requires science policy actions incentivizing research aimed at prevention and cancer therapeutics/care with an increased focus on patients' needs and cost-effective healthcare.

Combined Inhibition of EZH2 and FGFR is Synergistic in BAP1-deficient Malignant Mesothelioma

Malignant mesothelioma is a highly aggressive tumor with a survival of only 4-18 months after diagnosis. Treatment options for this disease are limited. Immune checkpoint blockade using ipilimumab and nivolumab has recently been approved as a frontline therapy, but this led to only a small improvement in overall patient survival. As more than half of patients with mesothelioma have alterations in the gene encoding for BAP1 this could be a potential marker for targeted therapies. In this study, we investigated the synergistic potential of combining EZH2 inhibition together with FGFR inhibition for treatment of BAP1-deficient malignancies. The efficacy of the combination was evaluated using human and murine preclinical models of mesothelioma and uveal melanoma in vitro. The efficacy of the combination was further validated in vivo by using BAP1-deficient mesothelioma xenografts and autochthonous mouse models. In vitro data showed sensitivity to the combined inhibition in BAP1-deficient mesothelioma and uveal melanoma tumor cell lines but not for BAP1-proficient subtypes. In vivo data showed susceptibility to the combination of BAP1-deficient xenografts and demonstrated an increase of survival in autochthonous models of mesothelioma. These results highlight the potential of this novel drug combination for the treatment of mesothelioma using BAP1 as a biomarker. Given these encouraging preclinical results, it will be important to clinically explore dual EZH2/FGFR inhibition in patients with BAP1-deficient malignant mesothelioma and justify further exploration in other BAP1 loss-associated tumors.

SIGNIFICANCE

Despite the recent approval of immunotherapy, malignant mesothelioma has limited treatment options and poor prognosis. Here, we observe that EZH2 inhibitors dramatically enhance the efficacy of FGFR inhibition, sensitising BAP1-mutant mesothelioma and uveal melanoma cells. The striking synergy of EZH2 and FGFR inhibition supports clinical investigations for BAP1-mutant tumors.

Engaging European society at the forefront of cancer research and care: How discussions at the 5th Gago Conference on European Science policy led to the Heidelberg Manifesto

European cancer research stakeholders met in October 2022 in Heidelberg, Germany, at the 5th Gago conference on European Cancer Policy, to discuss the current cancer research and cancer care policy landscape in Europe. Meeting participants highlighted gaps in the existing European programmes focusing on cancer research, including Europe's Beating Cancer Plan (EBCP), the Mission on Cancer (MoC), Understanding Cancer (UNCAN.eu), and the joint action CRANE, and put forward the next priorities, in the form of the Heidelberg Manifesto for cancer research. This meeting report presents all discussions that shed light on how infrastructures can be effectively shaped for translational, prevention, clinical and outcomes cancer research, with a focus on implementation and sustainability and while engaging patients and the public. In addition, we summarize recommendations on how to introduce frameworks for the digitalization of European cancer research. Finally, we discuss what structures, commitment, and resources are needed to establish a collaborative cancer research environment in Europe to achieve the scale required for innovation.

Sentinels of chromatin: chromodomain helicase DNA-binding proteins in development and disease

Chromatin is highly dynamic, undergoing continuous global changes in its structure and type of histone and DNA modifications governed by processes such as transcription, repair, replication, and recombination. Members of the chromodomain helicase DNA-binding (CHD) family of enzymes are ATP-dependent chromatin remodelers that are intimately involved in the regulation of chromatin dynamics, altering nucleosomal structure and DNA accessibility. Genetic studies in yeast, fruit flies, zebrafish, and mice underscore essential roles of CHD enzymes in regulating cellular fate and identity, as well as proper embryonic development. With the advent of next-generation sequencing, evidence is emerging that these enzymes are subjected to frequent DNA copy number alterations or mutations and show aberrant expression in malignancies and other human diseases. As such, they might prove to be valuable biomarkers or targets for therapeutic intervention.

The Porto European Cancer Research Summit 2021

Key stakeholders from the cancer research continuum met in May 2021 at the European Cancer Research Summit in Porto to discuss priorities and specific action points required for the successful implementation of the European Cancer Mission and Europe's Beating Cancer Plan (EBCP). Speakers presented a unified view about the need to establish high-quality, networked infrastructures to decrease cancer incidence, increase the cure rate, improve patient's survival and quality of life, and deal with research and care inequalities across the European Union (EU). These infrastructures, featuring Comprehensive Cancer Centres (CCCs) as key components, will integrate care, prevention and research across the entire cancer continuum to support the development of personalized/precision cancer medicine in Europe. The three pillars of the recommended European infrastructures - namely translational research, clinical/prevention trials and outcomes research - were pondered at length. Speakers addressing the future needs of translational research focused on the prospects of multiomics assisted preclinical research, progress in Molecular and Digital Pathology, immunotherapy, liquid biopsy and science data. The clinical/prevention trial session presented the requirements for next-generation, multicentric trials entailing unified strategies for patient stratification, imaging, and biospecimen acquisition and storage. The third session highlighted the need for establishing outcomes research infrastructures to cover primary prevention, early detection, clinical effectiveness of innovations, health-related quality-of-life assessment, survivorship research and health economics. An important outcome of the Summit was the presentation of the Porto Declaration, which called for a collective and committed action throughout Europe to develop the cancer research infrastructures indispensable for fostering innovation and decreasing inequalities within and between member states. Moreover, the Summit guidelines will assist decision making in the context of a unique EU-wide cancer initiative that, if expertly implemented, will decrease the cancer death toll and improve the quality of life of those confronted with cancer, and this is carried out at an affordable cost.

FGFR1 Oncogenic Activation Reveals an Alternative Cell of Origin of SCLC in Rb1/p53 Mice

Fibroblast growth factor receptor 1 (FGFR1) is frequently amplified in human small-cell lung cancer (SCLC), but its contribution to SCLC and other lung tumors has remained elusive. Here, we assess the tumorigenic capacity of constitutive-active FGFR1 (FGFR1^K656E) with concomitant RB and P53 depletion in mouse lung. Our results reveal a context-dependent effect of FGFR1^K656E: it impairs SCLC development from CGRP^POS neuroendocrine (NE) cells, which are considered the major cell of origin of SCLC, whereas it promotes SCLC and low-grade NE bronchial lesions from tracheobronchial-basal cells. Moreover, FGFR1^K656E induces lung adenocarcinoma (LADC) from most lung cell compartments. However, its expression is not sustained in LADC originating from CGRP^POS cells. Therefore, cell context and tumor stage should be taken into account when considering FGFR1 inhibition as a therapeutic option.

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FGRF signaling impairs SCLC development initiated from CGRP^POS NE cells

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FGRF signaling promotes development of NE tumors initiated from K14^POS cells

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Rb;p53;Fgfr1 mice develop ADCs that retain signatures of their cell of origin

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Low expression of Fgfr1 in progressed tumors suggests a role in tumor initiation

Combined deletion of Bap1, Nf2, and Cdkn2ab causes rapid onset of malignant mesothelioma in mice

We have generated mouse models of malignant mesothelioma (MM) based upon disruption of the Bap1, Nf2, and Cdkn2ab tumor suppressor loci in various combinations as also frequently observed in human MM. Inactivation of all three loci in the mesothelial lining of the thoracic cavity leads to a highly aggressive MM that recapitulates the histological features and gene expression profile observed in human patients. The tumors also show a similar inflammatory phenotype. Bap1 deletion alone does not cause MM but dramatically accelerates MM development when combined with Nf2 and Cdkn2ab (hereafter BNC) disruption. The accelerated tumor development is accompanied by increased Polycomb repression and EZH2-mediated redistribution of H3K27me3 toward promoter sites with concomitant activation of PI3K and MAPK pathways. Treatment of BNC tumor–bearing mice with cisplatin and pemetrexed, the current frontline treatment, prolongs survival. This makes the autochthonous mouse model described here very well suited to explore the pathogenesis of MM and validate new treatment regimens for MM, including immunotherapy.

How the COVID-19 pandemic highlights the necessity of animal research

Recently, a petition was offered to the European Commission calling for an immediate ban on animal testing. Although a Europe-wide moratorium on the use of animals in science is not yet possible, there has been a push by the non-scientific community and politicians for a rapid transition to animal-free innovations. Although there are benefits for both animal welfare and researchers, advances on alternative methods have not progressed enough to be able to replace animal research in the foreseeable future. This trend has led first and foremost to a substantial increase in the administrative burden and hurdles required to make timely advances in research and treatments for human and animal diseases. The current COVID-19 pandemic clearly highlights how much we actually rely on animal research. COVID-19 affects several organs and systems, and the various animal-free alternatives currently available do not come close to this complexity. In this Essay, we therefore argue that the use of animals is essential for the advancement of human and veterinary health.

Cells of origin of lung cancers: lessons from mouse studies

As one of the most common forms of cancer, lung cancers present as a collection of different histological subtypes. These subtypes are characterized by distinct sets of driver mutations and phenotypic appearance, and they often show varying degrees of heterogenicity, aggressiveness, and response/resistance to therapy. Intriguingly, lung cancers are also capable of showing features of multiple subtypes or converting from one subtype to another. The intertumoral and intratumoral heterogeneity of lung cancers as well as incidences of subtype transdifferentiation raise the question of to what extent the tumor characteristics are dictated by the cell of origin rather than the acquired driver lesions. We provide here an overview of the studies in experimental mouse models that try to address this question. These studies convincingly show that both the cell of origin and the genetic driver lesions play a critical role in shaping the phenotypes of lung tumors. However, they also illustrate that there is far from a direct one-to-one relationship between the cell of origin and the cancer subtype, as most epithelial cells can be reprogrammed toward diverse lung cancer fates when exposed to the appropriate set of driver mutations.

Towards a cancer mission in Horizon Europe: recommendations

A comprehensive translational cancer research approach focused on personalized and precision medicine, and covering the entire cancer research-care-prevention continuum has the potential to achieve in 2030 a 10-year cancer-specific survival for 75% of patients diagnosed in European Union (EU) member states with a well-developed healthcare system. Concerted actions across this continuum that spans from basic and preclinical research through clinical and prevention research to outcomes research, along with the establishment of interconnected high-quality infrastructures for translational research, clinical and prevention trials and outcomes research, will ensure that science-driven and social innovations benefit patients and individuals at risk across the EU. European infrastructures involving comprehensive cancer centres (CCCs) and CCC-like entities will provide researchers with access to the required critical mass of patients, biological materials and technological resources and can bridge research with healthcare systems. Here, we prioritize research areas to ensure a balanced research portfolio and provide recommendations for achieving key targets. Meeting these targets will require harmonization of EU and national priorities and policies, improved research coordination at the national, regional and EU level and increasingly efficient and flexible funding mechanisms. Long-term support by the EU and commitment of Member States to specialized schemes are also needed for the establishment and sustainability of trans-border infrastructures and networks. In addition to effectively engaging policymakers, all relevant stakeholders within the entire continuum should consensually inform policy through evidence-based advice.

Gene expression regulation by the Chromodomain helicase DNA-binding protein 9 (CHD9) chromatin remodeler is dispensable for murine development

Chromodomain helicase DNA-binding (CHD) chromatin remodelers regulate transcription and DNA repair. They govern cell-fate decisions during embryonic development and are often deregulated in human pathologies. Chd1-8 show upon germline disruption pronounced, often developmental lethal phenotypes. Here we show that contrary to Chd1-8 disruption, Chd9-/-animals are viable, fertile and display no developmental defects or disease predisposition. Germline deletion of Chd9 only moderately affects gene expression in tissues and derived cells, whereas acute depletion in human cancer cells elicits more robust changes suggesting that CHD9 is a highly context-dependent chromatin regulator that, surprisingly, is dispensable for mouse development.

New Approaches to SCLC Therapy: From the Laboratory to the Clinic

The outcomes of patients with SCLC have not yet been substantially impacted by the revolution in precision oncology, primarily owing to a paucity of genetic alterations in actionable driver oncogenes. Nevertheless, systemic therapies that include immunotherapy are beginning to show promise in the clinic. Although, these results are encouraging, many patients do not respond to, or rapidly recur after, current regimens, necessitating alternative or complementary therapeutic strategies. In this review, we discuss ongoing investigations into the pathobiology of this recalcitrant cancer and the therapeutic vulnerabilities that are exposed by the disease state. Included within this discussion, is a snapshot of the current biomarker and clinical trial landscapes for SCLC. Finally, we identify key knowledge gaps that should be addressed to advance the field in pursuit of reduced SCLC mortality. This review largely summarizes work presented at the Third Biennial International Association for the Study of Lung Cancer SCLC Meeting.

Preclinical Models of Malignant Mesothelioma

Rodent models of malignant mesothelioma help facilitate the understanding of the biology of this highly lethal cancer and to develop and test new interventions. Introducing the same genetic lesions as found in human mesothelioma in mice results in tumors that show close resemblance with the human disease counterpart. This includes the extensive inflammatory responses that characterize human malignant mesothelioma. The relatively fast development of mesothelioma in mice when the appropriate combination of lesions is introduced, with or without exposure to asbestos, make the autochthonous models particularly useful for testing new treatment strategies in an immunocompetent setting, whereas Patient-Derived Xenograft models are particularly useful to assess effects of inter- and intra-tumor heterogeneity and human-specific features of mesothelioma. It is to be expected that new insights obtained by studying these experimental systems will lead to new more effective treatments for this devastating disease.

Tumor Heterogeneity Underlies Differential Cisplatin Sensitivity in Mouse Models of Small-Cell Lung Cancer

Small-cell lung cancer is the most aggressive type of lung cancer, characterized by a remarkable response to chemotherapy followed by development of resistance. Here, we describe SCLC subtypes in Mycl- and Nfib-driven GEMM that include CDH1-high peripheral primary tumor lesions and CDH1-negative, aggressive intrapulmonary metastases. Cisplatin treatment preferentially eliminates the latter, thus revealing a striking differential response. Using a combined transcriptomic and proteomic approach, we find a marked reduction in proliferation and metabolic rewiring following cisplatin treatment and present evidence for a distinctive metabolic and structural profile defining intrinsically resistant populations. This offers perspectives for effective combination therapies that might also hold promise for treating human SCLC, given the very similar response of both mouse and human SCLC to cisplatin.

A natural WNT signaling variant potently synergizes with Cdkn2ab loss in skin carcinogenesis

Cdkn2ab knockout mice, generated from 129P2 ES cells develop skin carcinomas. Here we show that the incidence of these carcinomas drops gradually in the course of backcrossing to the FVB/N background. Microsatellite analyses indicate that this cancer phenotype is linked to a 20 Mb region of 129P2 chromosome 15 harboring the Wnt7b gene, which is preferentially expressed from the 129P2 allele in skin carcinomas and derived cell lines. ChIPseq analysis shows enrichment of H3K27-Ac, a mark for active enhancers, in the 5' region of the Wnt7b 129P2 gene. The Wnt7b 129P2 allele appears sufficient to cause in vitro transformation of Cdkn2ab-deficient cell lines primarily through CDK6 activation. These results point to a critical role of the Cdkn2ab locus in keeping the oncogenic potential of physiological levels of WNT signaling in check and illustrate that GWAS-based searches for cancer predisposing allelic variants can be enhanced by including defined somatically acquired lesions as an additional input.

Inhibition of the Replication Stress Response Is a Synthetic Vulnerability in SCLC That Acts Synergistically in Combination with Cisplatin

Small cell lung cancer (SCLC) is generally regarded as very difficult to treat, mostly due to the development of metastases early in the disease and a quick relapse with resistant disease. SCLC patients initially show a good response to treatment with the DNA damaging agents cisplatin and etoposide. This is, however, quickly followed by the development of resistant disease, which urges the development of novel therapies for this type of cancer. In this study, we set out to compile a comprehensive overview of the vulnerabilities of SCLC. A functional genome-wide screen where all individual genes were knocked out was performed to identify novel vulnerabilities of SCLC. By analysis of the knockouts that were lethal to these cancer cells, we identified several processes to be synthetic vulnerabilities in SCLC. We were able to validate the vulnerability to inhibition of the replication stress response machinery by use of Chk1 and ATR inhibitors. Strikingly, SCLC cells were more sensitive to these inhibitors than nontransformed cells. In addition, these inhibitors work synergistically with either etoposide and cisplatin, where the interaction is largest with the latter. ATR inhibition by VE-822 treatment in combination with cisplatin also outperforms the combination of cisplatin with etoposide in vivo Altogether, our study uncovered a critical dependence of SCLC on the replication stress response and urges the validation of ATR inhibitors in combination with cisplatin in a clinical setting.

Quality-assured research environments for translational cancer research

In order to secure high-quality cancer care for increasing numbers of cancer patients in the upcoming decades, the complete continuum of cancer research and cancer care needs a thorough overhaul, with more emphasis on prevention and early detection, and a greater focus on the development of innovative treatments that are also scrutinised for effectiveness and quality-of-life aspects. Therefore, under-resourced research areas, such as primary prevention, early diagnosis/secondary prevention (Song et al., ; Wild et al., ) and outcomes research (Cavers et al., ), should be given more emphasis, whereas basic, preclinical and clinical cancer research requires more innovation and effective collaboration to develop more effective treatments at an affordable cost. Innovative collaborative research in this translational trajectory requires the participation of well-resourced and well-organised institutions that are committed to high scientific and ethical standards. Offering focused funding to distinct segments of this research continuum concomitant with incentives to aspire to high-quality standards is the most effective route to achieve these goals. Therefore, a rigorous quality assessment system for institutions operating in this research continuum is a high priority.

European Academy of Cancer Sciences - position paper

The European Academy of Cancer Sciences (EACS) is an independent advisory body of well-recognised medical specialists and researchers striving to create a compelling interactive continuum of cancer research, from innovative basic research to implementation of state-of-the-art evidence-based cancer care and prevention. Achieving the above will entail bridging high-quality basic and preclinical cancer research to research on prevention, early detection and therapeutics as well as improving coordination of translational research efforts across Europe. The latter is expected to be expedited through quality assuring translational cancer research in Comprehensive Cancer Centres - entities that link research with the healthcare system - and networks of cancer research centres. Achieving a critical mass of expertise, resources and patients is crucial. Improving late translational research, which involves clinical studies to assess effectiveness, and added value for the health care is also a high priority. Both high-quality Big Data collections and the intelligent use of these data will promote innovation in cancer research and support outcomes research to assess clinical utility, quality of cancer care and long-term follow-up of treated patients. The EACS supports the mission-oriented approach recently proposed by the European Commission in Horizon Europe to deal with major challenges and would like to persuade the EU and its member states to formally launch a mission in cancer to boost and streamline the cancer research continuum in Europe. Building a coherent translational cancer research continuum with a focus on patients and individuals at risk will require, however, foresight as well as the extensive and continuous provision of evidence-based advice to inform policy.

Transcriptomics and Transposon Mutagenesis Identify Multiple Mechanisms of Resistance to the FGFR Inhibitor AZD4547

In human cancers, FGFR signaling is frequently hyperactivated by deregulation of FGF ligands or by activating mutations in the FGFR receptors such as gene amplifications, point mutations, and gene fusions. As such, FGFR inhibitors are considered an attractive therapeutic strategy for patients with mutations in FGFR family members. We previously identified Fgfr2 as a key driver of invasive lobular carcinoma (ILC) in an in vivo insertional mutagenesis screen using the Sleeping Beauty transposon system. Here we explore whether these FGFR-driven ILCs are sensitive to the FGFR inhibitor AZD4547 and use transposon mutagenesis in these tumors to identify potential mechanisms of resistance to therapy. Combined with RNA sequencing-based analyses of AZD4547-resistant tumors, our in vivo approach identified several known and novel potential resistance mechanisms to FGFR inhibition, most of which converged on reactivation of the canonical MAPK-ERK signaling cascade. Observed resistance mechanisms included mutations in the tyrosine kinase domain of FGFR2, overexpression of MET, inactivation of RASA1, and activation of the drug-efflux transporter ABCG2. ABCG2 and RASA1 were identified only from de novo transposon insertions acquired during AZD4547 treatment, demonstrating that insertional mutagenesis in mice is an effective tool for identifying potential mechanisms of resistance to targeted cancer therapies.Significance: These findings demonstrate that a combined approach of transcriptomics and insertional mutagenesis in vivo is an effective method for identifying potential targets to overcome resistance to therapy in the clinic. Cancer Res; 78(19); 5668-79. ©2018 AACR.

Abstract IA06: Driver mutations and cell-of-origin as critical factors determining the phenotypic characteristics of thoracic tumor subtypes

We have generated mouse models for specific lung tumors and mesothelioma. These were based on the conditional somatic (in)activation of tumor suppressor genes and oncogenes. By using viruses driving Cre recombinase from specific promoters, we could achieve both sporadic and cell-type specific switching of the conditional alleles allowing us to address the importance of the target cell in the development of specific tumor subtypes. We made the following observations.

Small cell lung cancer (SCLC) development was fully dependent on the inactivation of Rb in conjunction with loss of p53. This neuroendocrine tumor could be most efficiently induced by targeting neuroendocrine cells using an Ad5-CGRP-Cre virus. However, when Rb and p53 were inactivated in combination with overexpression of L-myc, a gene frequently found amplified in both human and mouse, we noted additional tumors with a more peripheral location (more precisely at the bronchiolar-alveolar junction region) and with a less aggressive phenotype, but only when these tumors were induced by an Ad5-CMV-Cre virus. Since the latter tumors were strongly positive for neuroendocrine markers including CGRP, this indicates that the latter tumor subtype originated from a cell with no or very low CGRP expression and therefore different from the neuroendocrine cell targeted by Ad5-CGRP-Cre. The cell type giving rise to this tumor is not yet defined. Nevertheless, the different phenotypic characteristics of this tumor—that shows many of the features of SCLC—likely also have consequences for its prognosis and response to therapy.

In testing a number of different combinations of lesions to induce squamous cell carcinoma (SCC), we found that development of SCC strongly depended on the overexpression of Sox2. Biallelic inactivation of Pten and Cdkn2a;Cdkn2b;p19Arf in combination with Sox2 overexpression promoted SCC at high penetrance but after a relatively long latency period. Phenotypically mouse SCC closely resembled human SCC, showing a very similar immunophenotyped, indicating that this is largely commanded by the tumor subtype. Interestingly, SCC could be induced at the same extend by activating the aforementioned genetic lesions in Basal, Club, and Alveolar type II cells (AT2). When targeting the latter two cell subtypes, they went through a dedifferentiation/transdifferentiation process with the concomitant loss and gain of transient cell markers; e.g., when targeting AT2 cells, the cells would lose SPC expression, transiently express the Club marker CC10, to acquire subsequently the biomarker of SCC, K5, and p63. Histopathology showed a process of transdifferentiation of the alveolar cells to Club cells and eventually to neoplastic squamous cells. Although the cell-of-origin did influence the extent of progression of individual tumor nodules (more small lesions upon induction of transformation of AT2 cells), the phenotypic characteristics of the tumors were very similar and could not be distinguished on basis of RNA expression.

In the case of adenocarcinomas developing in LSL-KrasG12D;p53f/f mice, the cell-of-origin did again influence the tumor phenotype. When Club cells were targeted, the cells would lose the Club cell specific marker expression (CC10 and Sox2) and acquire pronounced SPC expression while such changes were not seen upon targeting AT2 cells. They retained their SPC expression. However, the tumors induced in Club cells showed a more pronounced papillary phenotype as well as a more aggressive growth pattern as compared to tumors induced in AT2 cells.

A similar situation was encountered in mesothelioma. Although this tumor is less stringently dependent on the specific lesions, loss of Nf2 in conjunction with p53 pathway inactivation and Cdkn2a loss is an effective route to malignant mesothelioma (MM). MM development can be further accelerated by BAP1 loss resulting in an autochthonous model that is as fast as tumor graft models. Some of the advantageous and disadvantages of each will be discussed.

MM can manifest as three major subtypes: epithelioid, sarcomatoid, and biphasic. Each of those can be induced by the same set of mutations (loss-of-function of Nf2, p53, and Cdkn2a). The tumor subtype that arises depends on the cell-of-origin. The three subtypes exhibit relative stable phenotypes with the phenotypic appearance of the biphasic tumor depending on the microenvironmental cues. Changing those makes this subtype either more epithelioid or sarcomatoid.

The examples described show that both the combination of genetic lesion and the cell-of-origin are critical factors defining tumor characteristics. In some cases, targeting different cell types with the same lesions gives rise to seemingly indistinguishable tumors (e.g., SCC), whereas in other cases the same genetic lesions cause tumor features that are strongly influenced by the cell-of-origin (as is the case in MM and SCLC), emphasizing that the cell-of-origin might be an important factor that should be taken into account when designing intervention strategies within otherwise highly similar tumors.

Citation Format: Anton Berns, Ekaterina Semenova, Giustina Ferone, Hilda de Vries, Jitendra Badhai, Min-chul Kwon, Kate Sutherland, Lorenzo Bombardelli, Rajith Bhaskaran, Ji-Ying Song. Driver mutations and cell-of-origin as critical factors determining the phenotypic characteristics of thoracic tumor subtypes [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr IA06.

Rejuvenation by Therapeutic Elimination of Senescent Cells

In this issue of Cell, Baar et al. show how FOXO4 protects senescent cell viability by keeping p53 sequestered in nuclear bodies, preventing it from inducing apoptosis. Disrupting this interaction with an all-D amino acid peptide (FOXO4-DRI) restores p53's apoptotic role and ameliorates the consequences of senescence-associated loss of tissue homeostasis.

Awakening of "Schlafen11" to Tackle Chemotherapy Resistance in SCLC

Chemotherapy resistance arises invariably in small cell lung cancer (SCLC). In this issue of Cancer Cell, Gardner et al. find that in some SCLC, EZH2 mediates resistance via downregulation of Schlafen11 (SLFN11). Combining EZH2 inhibition with chemotherapy effectively overcomes drug resistance of xenografted SCLC, holding promise for new treatment paradigms.

SOX2 Is the Determining Oncogenic Switch in Promoting Lung Squamous Cell Carcinoma from Different Cells of Origin

Lung squamous cell carcinoma (LSCC) is a devastating malignancy with no effective treatments, due to its complex genomic profile. Therefore, preclinical models mimicking its salient features are urgently needed. Here we describe mouse models bearing various combinations of genetic lesions predominantly found in human LSCC. We show that SOX2 but not FGFR1 overexpression in tracheobronchial basal cells combined with Cdkn2ab and Pten loss results in LSCC closely resembling the human counterpart. Interestingly, Sox2;Pten;Cdkn2ab mice develop LSCC with a more peripheral location when Club or Alveolar type 2 (AT2) cells are targeted. Our model highlights the essential role of SOX2 in commanding the squamous cell fate from different cells of origin and represents an invaluable tool for developing better intervention strategies.

Drugging the addict: non-oncogene addiction as a target for cancer therapy

Historically, cancers have been treated with chemotherapeutics aimed to have profound effects on tumor cells with only limited effects on normal tissue. This approach was followed by the development of small‐molecule inhibitors that can target oncogenic pathways critical for the survival of tumor cells. The clinical targeting of these so‐called oncogene addictions, however, is in many instances hampered by the outgrowth of resistant clones. More recently, the proper functioning of non‐mutated genes has been shown to enhance the survival of many cancers, a phenomenon called non‐oncogene addiction. In the current review, we will focus on the distinct non‐oncogenic addictions found in cancer cells, including synthetic lethal interactions, the underlying stress phenotypes, and arising therapeutic opportunities.

Transcription Factor NFIB Is a Driver of Small Cell Lung Cancer Progression in Mice and Marks Metastatic Disease in Patients

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor, and no effective treatment is available to date. Mouse models of SCLC based on the inactivation of Rb1 and Trp53 show frequent amplifications of the Nfib and Mycl genes. Here, we report that, although overexpression of either transcription factor accelerates tumor growth, NFIB specifically promotes metastatic spread. High NFIB levels are associated with expansive growth of a poorly differentiated and almost exclusively E-cadherin (CDH1)-negative invasive tumor cell population. Consistent with the mouse data, we find that NFIB is overexpressed in almost all tested human metastatic high-grade neuroendocrine lung tumors, warranting further assessment of NFIB as a tumor progression marker in a clinical setting.

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NFIB drives tumor initiation and progression in mouse models of SCLC

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NFIB enhances metastasis and changes the metastatic profile

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NFIB promotes dedifferentiation and invasion in SCLC

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NFIB marks stage III/IV high-grade neuroendocrine carcinomas in patients

Excellent translational research in oncology: A journey towards novel and more effective anti-cancer therapies

Comprehensive Cancer Centres (CCCs) serve as critical drivers for improving cancer survival. In Europe, we have developed an Excellence Designation System (EDS) consisting of criteria to assess "excellence" of CCCs in translational research (bench to bedside and back), with the expectation that many European CCCs will aspire to this status.

The steady progress of targeted therapies, promising advances for lung cancer

Lung cancer remains one of the most complex and challenging cancers, being responsible for almost a third of all cancer deaths. This grim picture seems however to be changing, for at least a subset of lung cancers. The number of patients who can benefit from targeted therapies is steadily increasing thanks to the progress made in identifying actionable driver lesions in lung tumours. The success of the latest generation of EGFR and ALK inhibitors in the clinic not only illustrates the value of targeted therapies, but also shows how almost inevitably drug resistance develops. Therefore, more sophisticated approaches are needed to achieve long-term remissions. Although there are still significant barriers to be overcome, technological advances in early detection of relevant mutations and the opportunity to test new drugs in predictive preclinical models justify the hope that we will overcome these obstacles.

Abstract IA05: Polycomb repressive complex-2 is a barrier to Kras-driven inflammation and epithelial-mesenchymal transition in non-small cell lung cancer

Polycomb repressive complexes (PRC) are frequently implicated in human cancer acting either as oncogenes or tumor suppressors. Here we show that PRC2 is a critical regulator of Kras-driven non-small-cell lung cancer (NSCLC) progression. Modulation of PRC2 by either Ezh2 overexpression or Eed deletion enhances Kras-driven adenomagenesis and inflammation, respectively. Eed-loss-driven inflammation leads to massive macrophage recruitment and marked decline in tissue function. Additional Trp53 inactivation activates a cell autonomous epithelial-to- mesenchymal transition (EMT) program leading to an invasive mucinous adenocarcinoma. A switch between methylated/acetylated chromatin underlies the tumor phenotypic evolution, prominently involving genes controlled by Hippo/Wnt-signaling. Our observations in the mouse models were conserved in human cells. Importantly, PRC2 inactivation results in context-dependent phenotypic alterations, with implications for its therapeutic application.

Citation Format: Michela Serresi, Gaetano Gargiulo, Nathalie Proost, Bjorn Siteur, Matteo Cesaroni, Martijn Koppens, Huafeng Xie, Kate Sutherland, Danielle Hulsman, Elisabetta Citterio, Stuart Orkin, Anton Berns, Maarten van Lohuizen. Polycomb repressive complex-2 is a barrier to Kras-driven inflammation and epithelial-mesenchymal transition in non-small cell lung cancer. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr IA05.

Human malignant mesothelioma is recapitulated in immunocompetent BALB/c mice injected with murine AB cells

Malignant Mesothelioma is a highly aggressive cancer, which is difficult to diagnose and treat. Here we describe the molecular, cellular and morphological characterization of a syngeneic system consisting of murine AB1, AB12 and AB22 mesothelioma cells injected in immunocompetent BALB/c mice, which allows the study of the interplay of tumor cells with the immune system. Murine mesothelioma cells, like human ones, respond to exogenous High Mobility Group Box 1 protein, a Damage-Associated Molecular Pattern that acts as a chemoattractant for leukocytes and as a proinflammatory mediator. The tumors derived from AB cells are morphologically and histologically similar to human MM tumors, and respond to treatments used for MM patients. Our system largely recapitulates human mesothelioma, and we advocate its use for the study of MM development and treatment.

Polycomb Repressive Complex 2 Is a Barrier to KRAS-Driven Inflammation and Epithelial-Mesenchymal Transition in Non-Small-Cell Lung Cancer

Polycomb repressive complexes (PRC) are frequently implicated in human cancer, acting either as oncogenes or tumor suppressors. Here, we show that PRC2 is a critical regulator of KRAS-driven non-small cell lung cancer progression. Modulation of PRC2 by either Ezh2 overexpression or Eed deletion enhances KRAS-driven adenomagenesis and inflammation, respectively. Eed-loss-driven inflammation leads to massive macrophage recruitment and marked decline in tissue function. Additional Trp53 inactivation activates a cell-autonomous epithelial-to-mesenchymal transition program leading to an invasive mucinous adenocarcinoma. A switch between methylated/acetylated chromatin underlies the tumor phenotypic evolution, prominently involving genes controlled by Hippo/Wnt signaling. Our observations in the mouse models were conserved in human cells. Importantly, PRC2 inactivation results in context-dependent phenotypic alterations, with implications for its therapeutic application.

Using the GEMM-ESC strategy to study gene function in mouse models

Preclinical in vivo validation of target genes for therapeutic intervention requires careful selection and characterization of the most suitable animal model in order to assess the role of these genes in a particular process or disease. To this end, genetically engineered mouse models (GEMMs) are typically used. However, the appropriate engineering of these models is often cumbersome and time consuming. Recently, we and others described a modular approach for fast-track modification of existing GEMMs by re-derivation of embryonic stem cells (ESCs) that can be modified by recombinase-mediated transgene insertion and subsequently used for the production of chimeric mice. This 'GEMM-ESC strategy' allows for rapid in vivo analysis of gene function in the chimeras and their offspring. Moreover, this strategy is compatible with CRISPR/Cas9-mediated genome editing. This protocol describes when and how to use the GEMM-ESC strategy effectively, and it provides a detailed procedure for re-deriving and manipulating GEMM-ESCs under feeder- and serum-free conditions. This strategy produces transgenic mice with the desired complex genotype faster than traditional methods: generation of validated GEMM-ESC clones for controlled transgene integration takes 9-12 months, and recombinase-mediated transgene integration and chimeric cohort production takes 2-3 months. The protocol requires skills in embryology, stem cell biology and molecular biology, and it is ideally performed within, or in close collaboration with, a transgenic facility.

Origins, genetic landscape, and emerging therapies of small cell lung cancer

Lung cancer is the leading cause of cancer deaths, with small cell lung cancer (SCLC) representing the most aggressive subtype. Standard treatments have not changed in decades, and the 5-year survival rate has remained <7%. Genomic analyses have identified key driver mutations of SCLC that were subsequently validated in animal models of SCLC. To provide better treatment options, a deeper understanding of the cellular and molecular mechanisms underlying SCLC initiation, progression, metastasis, and acquisition of resistance is required. In this review, we describe the genetic landscape of SCLC, features of the cell of origin, and targeted therapeutic approaches.

Wnt Down, Tumors Wind Up?

In mouse intestinal tumors induced by the inhibition of APC, the restoration of APC function causes complete tumor regression with normal differentiation and return of stem cell function irrespective of whether tumors also carried mutations in Kras and p53. These findings by Dow et al. validate the Wnt pathway as an exquisite target for intervention.

Abstract LB-201: Functional role for tumor heterogeneity: Paracrine signaling between tumor subclones of mouse SCLC promotes metastasis

Tumor heterogeneity might not only lead to pools of cells with a different resistance profile to therapy, the heterogeneity can also create a unique tumor-microenvironment. Earlier we have shown that clonal evolution in mouse SCLC can result in subclones with either neuro-endocrine (NE) and non-NE features. Co-grafting of such subclones endow the NE tumor cells with metastatic potential. To address the underlying mechanism we conducted a series of in vivo graft experiments and found that non-cell autonomous paracrine signaling is required in the subcutaneously grafted tumor to permit dissemination. The expression of transcription factor Pea3 in NE cells was identified as a functional downstream target of this paracrine interaction between the tumor subclones. Fgf2 secreted by non-NE subclones causes the expression of Pea3 in the NE cells through activation of Mapk pathway thereby temporarily potentiating its invasive capacity and facilitating intravasation into the circulation. These findings reveal a cooperating role of tumor cell subclones in mouse SCLC. Our data indicate that inhibition of the Fgf2/Mapk/Pea3 axis might be exploited to impair growth and metastatic spread of SCLC. Given the similarity in phenotypic tumor cell heterogenenity and signaling aberrations between mouse and human SCLC, inhibition of this signaling axis is therefore worth exploring in human SCLC.

Citation Format: Min Chul Kwon, Natalie Proost, Kate Sutherland, John Zevenhoven, Anton Berns. Functional role for tumor heterogeneity: Paracrine signaling between tumor subclones of mouse SCLC promotes metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-201. doi:10.1158/1538-7445.AM2015-LB-201

Paracrine signaling between tumor subclones of mouse SCLC: a critical role of ETS transcription factor Pea3 in facilitating metastasis

Kwon et al. show that paracrine signaling between SCLC subclones is a critical requirement in the early steps of the metastatic process. Paracrine signaling via Fgf2 and MAPK between these diverged tumor subclones causes enhanced expression of the Pea3 transcription factor, resulting in metastatic dissemination of the neuroendocrine tumor subclones.

Tumor heterogeneity can create a unique symbiotic tumor microenvironment. Earlier, we showed that clonal evolution in mouse small cell lung cancer (SCLC) can result in subclones that, upon cografting, endow the neuroendocrine tumor cells with metastatic potential. We now show that paracrine signaling between SCLC subclones is a critical requirement in the early steps of the metastatic process, such as local invasion and intravasation. We further show evidence that paracrine signaling via fibroblast growth factor 2 (Fgf2) and Mapk between these diverged tumor subclones causes enhanced expression of the Pea3 (polyomavirus enhancer activator 3) transcription factor, resulting in metastatic dissemination of the neuroendocrine tumor subclones. Our data reveal for the first time paracrine signaling between tumor cell subclones in SCLC that results in metastatic spread of SCLC.