RhoA downregulation in the murine intestinal epithelium results in chronic Wnt activation and increased tumorigenesis

Rho GTPases are molecular switches regulating multiple cellular processes. To investigate the role of RhoA in normal intestinal physiology, we used a conditional mouse model overexpressing a dominant negative RhoA mutant (RhoAT19N) in the intestinal epithelium. Although RhoA inhibition did not cause an overt phenotype, increased levels of nuclear β-catenin were observed in the small intestinal epithelium of RhoAT19N mice, and the overexpression of multiple Wnt target genes revealed a chronic activation of Wnt signaling. Elevated Wnt signaling in RhoAT19N mice and intestinal organoids did not affect the proliferation of intestinal epithelial cells but significantly interfered with their differentiation. Importantly, 17-month-old RhoAT19N mice showed a significant increase in the number of spontaneous intestinal tumors. Altogether, our results indicate that RhoA regulates the differentiation of intestinal epithelial cells and inhibits tumor initiation, likely through the control of Wnt signaling, a key regulator of proliferation and differentiation in the intestine.

BRAF activation by metabolic stress promotes glycolysis sensitizing NRASQ61-mutated melanomas to targeted therapy

NRAS-mutated melanoma lacks a specific line of treatment. Metabolic reprogramming is considered a novel target to control cancer; however, NRAS-oncogene contribution to this cancer hallmark is mostly unknown. Here, we show that NRAS^Q61-mutated melanomas specific metabolic settings mediate cell sensitivity to sorafenib upon metabolic stress. Mechanistically, these cells are dependent on glucose metabolism, in which glucose deprivation promotes a switch from CRAF to BRAF signaling. This scenario contributes to cell survival and sustains glucose metabolism through BRAF-mediated phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-2/3 (PFKFB2/PFKFB3). In turn, this favors the allosteric activation of phosphofructokinase-1 (PFK1), generating a feedback loop that couples glycolytic flux and the RAS signaling pathway. An in vivo treatment of NRAS^Q61 mutant melanomas, including patient-derived xenografts, with 2-deoxy-D-glucose (2-DG) and sorafenib effectively inhibits tumor growth. Thus, we provide evidence for NRAS-oncogene contributions to metabolic rewiring and a proof-of-principle for the treatment of NRAS^Q61-mutated melanoma combining metabolic stress (glycolysis inhibitors) and previously approved drugs, such as sorafenib.

Abstract 847: Role of RHOA in diffuse gastric cancer tumors

Gastric cancer constitutes the third leading cause of cancer mortality worldwide and tumors with diffuse histology have poor prognosis and low response rates to therapy. Missense mutations in the RHOA (Ras homolog family member A) GTPase have recently been identified in 24% of patients with diffuse gastric cancer. RHOA mutations are not randomly distributed along the coding sequence, but enriched in specific and recurrent hotspots. Substitution in codon 42 (Y42C) occurs in approximately 50% of the patients in which RHOA is mutated. RHOA orchestrates cellular processes such as proliferation, differentiation, migration and invasion, whose deregulation is essential for the onset, maintenance and progression of tumors. However, the functional role of wild type RHOA and RHOA mutants remains poorly characterized in gastric cancer. We used isogenic cell lines systems and animal models to study the impact of RHOA in the gastric tumorigenesis. RHOA loss strongly increased the proliferation, migration and invasion of diffuse gastric cancer cells in vitro, but also when growing as subcutaneous xenografts in immunodeficient mice, and in experimental mouse models of peritoneal and lung metastasis. Stomach tumor burden was also increased in transgenic mice conditionally expressing a dominant negative form of RHOA in the gastrointestinal tract (RHOA T19N). Moreover, cells overexpressing wild-type RHOA or G14V RHOA (a constitutive active form of the GTPase) exhibited reduced tumorigenic features both in vitro and in vivo. Conversely, diffuse gastric cancer cells engineered for overexpressing RHOA Y42C mutant, displayed enhanced growth and invasion in vitro. Importantly, stomach cancer tumors formed more efficiently in a transgenic mouse model in which we targeted the expression of Y42C RHOA mutant to the gastric epithelium. Collectively, these results demonstrate that RHOA has tumor-suppressive activity in diffuse gastric cancer, while the recurrent Y42C hotspot RHOA mutation found in these tumors is oncogenic.

Citation Format: Agueda Martinez-Barriocanal, Higinio Dopeso, Lizbeth M. Jiménez-Flores, Juliana C. Santos, Estefania Anguita, Josipa Bilic, Rocio Nieto, Elia García-Vidal, Manuel Sánchez Martín, Stefania Landolfi, Kazuto Kobayashi, Javier Hernandez-Losa, Simo Schwartz, Santiago Ramón y Cajal, Diego Arango. Role of RHOA in diffuse gastric cancer tumors [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 847.

High levels of chromosomal aberrations negatively associate with benefit to checkpoint inhibition in NSCLC

BACKGROUND

Immune checkpoint inhibitors (ICIs) targeting the programmed cell death 1/programmed death-ligand 1 axis have transformed the management of advanced non-small cell lung cancer (NSCLC). However, many patients do not benefit from this type of treatment, and thus several molecular biomarkers of benefit have been explored. The value of somatic copy number alterations (SCNAs) burden remains elusive.

PATIENTS AND METHODS

We assembled a cohort of 109 patients with NSCLC treated with ICIs and available tumor samples. We performed shallow whole-genome sequencing on 89 patients to determine genome-wide SCNAs and targeted gene expression analysis on 63 patients to study immune infiltration. We analyzed SCNAs burden in different ways (ie, the fraction of the genome altered or number of events) and studied their association with ICIs benefit based on survival analysis. We correlated SCNAs burden and immune infiltration on 35 patients of our cohort and on patients with lung adenocarcinoma from The Cancer Genome Atlas (TCGA).

RESULTS

High SCNAs burden, computed in diverse ways, is negatively associated with ICIs progression-free survival (PFS), with the fraction of the genome altered (FGA) by arm and chromosome events showing the strongest association with PFS (p=0.002) (n=77). Nevertheless, we found differences in SCNAs across some clinicopathological features (sample site origin). A multivariate analysis adjusted for relevant characteristics showed that the FGA of arm and chromosome alterations was strongly associated with PFS (HR=2.21, p=3.3 x 10^-5). Finally, we confirmed that SCNAs burden negatively correlates with tumor immune infiltration (n=35), although this correlation was not found for the males studied. Similar results were observed in the TCGA cohort.

CONCLUSIONS

SCNAs burden is a potential biomarker of benefit to ICIs in patients with NSCLC, although there appear to be some nuances worth consideration. Further studies will be needed to establish its role as a biomarker of benefit to ICIs.

Mesenchymal Stem Cells Delivery in Individuals with Different Pathologies: Multimodal Tracking, Safety and Future Applications

Due to their ease of isolation and their properties, mesenchymal stem cells (MSCs) have been widely investigated. MSCs have been proved capable of migration towards areas of inflammation, including tumors. Therefore, they have been suggested as vectors to carry therapies, specifically to neoplasias. As most of the individuals joining clinical trials that use MSCs for cancer and other pathologies are carefully recruited and do not suffer from other diseases, here we decided to study the safety and application of iv-injected MSCs in animals simultaneously induced with different inflammatory pathologies (diabetes, wound healing and tumors). We studied this by in vitro and in vivo approaches using different gene reporters (GFP, hNIS, and f-Luc) and non-invasive techniques (PET, BLI, or fluorescence). Our results found that MSCs reached different organs depending on the previously induced pathology. Moreover, we evaluated the property of MSCs to target tumors as vectors to deliver adenoviruses, including the interaction between tumor microenvironment and MSCs on their arrival. Mechanisms such as transdifferentiation, MSC fusion with cells, or paracrine processes after MSCs homing were studied, increasing the knowledge and safety of this new therapy for cancer.

Prognostic Impact of KRAS G12C Mutation in Patients With NSCLC: Results From the European Thoracic Oncology Platform Lungscape Project

INTRODUCTION

KRAS mutations, the most frequent gain-of-function alterations in NSCLC, are currently emerging as potential predictive therapeutic targets. The role of KRAS-G12C (Kr_G12C) is of special interest after the recent discovery and preclinical analyses of two different Kr_G12C covalent inhibitors (AMG-510, MRTX849).

METHODS

KRAS mutations were evaluated in formalin-fixed, paraffin-embedded tissue sections by a microfluidic-based multiplex polymerase chain reaction platform as a component of the previously published European Thoracic Oncology Platform Lungscape 003 Multiplex Mutation study, of clinically annotated, resected, stage I to III NSCLC. In this study, -Kr_G12C mutation prevalence and its association with clinicopathologic characteristics, molecular profiles, and postoperative patient outcome (overall survival, relapse-free survival, time-to-relapse) were explored.

RESULTS

KRAS gene was tested in 2055 Lungscape cases (adenocarcinomas: 1014 [49%]) with I or II or III stage respective distribution of 53% or 24% or 22% and median follow-up of 57 months. KRAS mutation prevalence in the adenocarcinoma cohort was 38.0% (95% confidence interval (CI): 35.0% to 41.0%), with Kr_G12C mutation representing 17.0% (95% CI: 14.7% to 19.4%). In the "histologic-subtype" cohort, Kr_G12C prevalence was 10.5% (95% CI: 9.2% to 11.9%). When adjusting for clinicopathologic characteristics, a significant negative prognostic effect of Kr_G12C presence versus other KRAS mutations or nonexistence of KRAS mutation was identified in the adenocarcinoma cohort alone and in the "histologic-subtype" cohort. For overall survival in adenocarcinomas, hazard ratio (HR)_{G12C versus other KRAS} is equal to 1.39 (95% CI: 1.03 to 1.89, p = 0.031) and HR_{G12C versus no KRAS} is equal to 1.32 (95% CI: 1.03 to 1.69, p = 0.028) (both also significant in the "histologic-subtype" cohort). For time-to-relapse, HR_{G12C versus other KRAS} is equal to 1.41 (95% CI: 1.03 to 1.92, p = 0.030). In addition, among all patients, for relapse-free survival, HR_{G12C versus no KRAS} is equal to 1.27 (95% CI: 1.04 to 1.54, p = 0.017).

CONCLUSIONS

In this large, clinically annotated stage I to III NSCLC cohort, the specific Kr_G12C mutation is significantly associated with poorer prognosis (adjusting for clinicopathologic characteristics) among adenocarcinomas and in unselected NSCLCs.

STK11 (LKB1) missense somatic mutant isoforms promote tumor growth, motility and inflammation

Elucidating the contribution of somatic mutations to cancer is essential for personalized medicine. STK11 (LKB1) appears to be inactivated in human cancer. However, somatic missense mutations also occur, and the role/s of these alterations to this disease remain unknown. Here, we investigated the contribution of four missense LKB1 somatic mutations in tumor biology. Three out of the four mutants lost their tumor suppressor capabilities and showed deficient kinase activity. The remaining mutant retained the enzymatic activity of wild type LKB1, but induced increased cell motility. Mechanistically, LKB1 mutants resulted in differential gene expression of genes encoding vesicle trafficking regulating molecules, adhesion molecules and cytokines. The differentially regulated genes correlated with protein networks identified through comparative secretome analysis. Notably, three mutant isoforms promoted tumor growth, and one induced inflammation-like features together with dysregulated levels of cytokines. These findings uncover oncogenic roles of LKB1 somatic mutations, and will aid in further understanding their contributions to cancer development and progression.

Paula Granado-Martínez, Sara Ortega, Elena González-Sánchez et al. report a functional analysis of four cancer-associated mutant isoforms of the gene STK11 using cell-based and animal models. They find the mutant isoforms no longer show tumor suppressor activity, promote tumor growth, and affect the regulation of cytokines and genes involved in vesicle trafficking.

Integrating clinical, molecular, proteomic and histopathological data within the tissue context: tissunomics

Malignant tumours show a marked degree of morphological, molecular and proteomic heterogeneity. This variability is closely related to microenvironmental factors and the location of the tumour. The activation of genetic alterations is very tissue‐dependent and only few tumours have distinct genetic alterations. Importantly, the activation state of proteins and signaling factors is heterogeneous in the primary tumour and in metastases and recurrences. The molecular diagnosis based only on genetic alterations can lead to treatments with unpredictable responses, depending on the tumour location, such as the tumour response in melanomas versus colon carcinomas with BRAF mutations. Therefore, we understand that the correct evaluation of tumours requires a system that integrates both morphological, molecular and protein information in a clinical and pathological context, where intratumoral heterogeneity can be assessed. Thus, we propose the term ‘tissunomics’, where the diagnosis will be contextualised in each tumour based on the complementation of the pathological, molecular, protein expression, environmental cells and clinical data.

The umbilical cord, preeclampsia and the VEGF family

Introduction

The VEGF family has been identified as abnormal in preeclampsia (PE). Hypertensive disorders of pregnancy (HDP) are major contributors to maternal and neonatal morbidity and mortality worldwide; likewise, umbilical cord anatomical abnormalities (UCAA) are linked to poor neonatal outcomes. Based on the relationship described between PE and UCAA and the role of the VEGF family in PE, this study explored VEGF expression in placental and UC tissued from patients with PE and with UCAA.

Methods

We performed an observational, analytical study on placentas, comparing protein and mRNA expression in four groups: patients with PE, patients with UC abnormalities, patients with both, and patients with none of them. Using immunohistochemistry, we studied VEGF A, VEGF R1 (FLT1), MMP1, and PLGF. With quantitative reverse transcription polymerase chain reaction we described mRNA expression of PLGF, VEGF and sFLT1, and sFLT1/PLGF ratio.

Results

Forty newborns were included. Sixty-seven percent of mothers and 45% of newborns developed no complications. Immunohistochemistry was performed on UC and placental disc paraffin-embedded tissue; in the latter, the mRNA of the VEGF family was also measured. Statistically significant differences were observed among different expressions in both HDP and UCAA groups. Interestingly, the UCAA group exhibited lower levels of sFLT1 and VEGF-A in comparison with other groups, with significant P-value for sFLT1 (P=0000.1).

Conclusion

The origin of UCAA abnormalities and their relation with HDP are still unknown. VEGF family alterations could be involved in both. This study provides the first approach related to molecules linked to UCAA.

Phenformin-Induced Mitochondrial Dysfunction Sensitizes Hepatocellular Carcinoma for Dual Inhibition of mTOR

Purpose: Hepatocellular carcinoma (HCC) ranks second in cancer mortality and has limited therapeutic options. We recently described the synergistic effect of allosteric and ATP-site competitive inhibitors against the mTOR for the treatment of HCC. However, such inhibitors induce hyperglycemia and increase mitochondrial efficiency. Here we determined whether the mitochondrial complex I inhibitor phenformin could reverse both side effects, impose an energetic stress on cancer cells, and suppress the growth of HCC.Experimental Design: Human HCC cell lines were used in vitro to access the signaling and energetic impact of mTOR inhibitors and phenformin, either alone or in combination. Next, the therapeutic utility of these drugs alone or in combination was investigated preclinically in human orthotopic tumors implanted in mice, by analyzing their impact on the tumor burden and overall survival.Results: We found phenformin caused mitochondrial dysfunction and fragmentation, inducing a compensatory shift to glycolysis. In contrast, dual inhibition of mTOR impaired cell growth and glycolysis, while increasing mitochondrial fusion and efficiency. In a mouse model of human HCC, dual inhibition of mTOR, together with phenformin, was highly efficacious in controlling tumor burden. However, more strikingly, pretreatment with phenformin sensitized tumors to dual inhibition of mTOR, leading to a dramatic improvement in survival.Conclusions: Treatment of HCC cells in vitro with the biguanide phenformin causes a metabolic shift to glycolysis, mitochondrial dysfunction and fragmentation, and dramatically sensitizes orthotopic liver tumors to dual inhibition of mTOR. We therefore propose this therapeutic approach should be tested clinically in HCC. Clin Cancer Res; 24(15); 3767-80. ©2018 AACR.

Evaluation of NGS and RT-PCR Methods for ALK Rearrangement in European NSCLC Patients: Results from the European Thoracic Oncology Platform Lungscape Project

INTRODUCTION

The reported prevalence of ALK receptor tyrosine kinase gene (ALK) rearrangement in NSCLC ranges from 2% to 7%. The primary standard diagnostic method is fluorescence in situ hybridization (FISH). Recently, immunohistochemistry (IHC) has also proved to be a reproducible and sensitive technique. Reverse-transcriptase polymerase chain reaction (RT-PCR) has also been advocated, and most recently, the advent of targeted next-generation sequencing (NGS) for ALK and other fusions has become possible. This study compares anaplastic lymphoma kinase (ALK) evaluation with all four techniques in resected NSCLC from the large European Thoracic Oncology Platform Lungscape cohort.

METHODS

A total of 96 cases from the European Thoracic Oncology Platform Lungscape iBiobank, with any ALK immunoreactivity were examined by FISH, central RT-PCR, and NGS. An H-score higher than 120 defines IHC positivity. RNA was extracted from the same formalin-fixed, paraffin-embedded tissues. For RT-PCR, primers covered the most frequent ALK translocations. For NGS, the Oncomine Solid Tumour Fusion Transcript Kit (Thermo Fisher Scientific, Waltham, MA) was used. The concordance was assessed using the Cohen κ coefficient (two-sided α ≤ 5%).

RESULTS

NGS provided results for 77 of the 95 cases tested (81.1%), whereas RT-PCR provided results for 77 of 96 (80.2%). Concordance occurred in 55 cases of the 60 cases tested with all four methods (43 ALK negative and 12 ALK positive). Using ALK copositivity for IHC and FISH as the criterion standard, we derived a sensitivity for RT-PCR/NGS of 70.0%/85.0%, with a specificity of 87.1%/79.0%. When either RT-PCR or NGS was combined with IHC, the sensitivity remained the same, whereas the specificity increased to 88.7% and 83.9% respectively.

CONCLUSION

NGS evaluation with the Oncomine Solid Tumour Fusion transcript kit and RT-PCR proved to have high sensitivity and specificity, advocating their use in routine practice. For maximal sensitivity and specificity, ALK status should be assessed by using two techniques and a third one in discordant cases. We therefore propose a customizable testing algorithm. These findings significantly influence existing testing paradigms and have clear clinical and economic impact.

Genetic profile of GNAQ-mutated blue melanocytic neoplasms reveals mutations in genes linked to genomic instability and the PI3K pathway

Melanomas arising in association with a common or cellular blue nevus (MABN) comprise a relatively rare and heterogeneous group of lethal melanomas. Although GNAQ is known to be frequently mutated in common blue nevus, cellular blue nevus (CBN) and MABN and these malignant lesions present gross chromosome alterations harboring BAP1 mutations, little is known about other mutations that contribute to the development and progression of these neoplasms. Thus, the genetic profile of these tumors is important to increase the number of intervention and treatment modalities. Here, we characterized and genetically profiled two different sections of a rare MABN and two CBNs from three different patients. All of the samples harbored a GNAQ mutation, exhibited RAS pathway activation, and harbored additional mutations in genes associated with genomic instability and epigenetic regulation (KMT2C, FANCD2, ATR, ATRX, NBN, ERCC2, SETD2, and WHSC1). In addition, all neoplasms harbored mutations that directly or indirectly affected either the regulation or activation of the PI3K pathway (PIK3CA, NF1, INPP5B and GSK3B). Our results not only help understand the genetic complexity of these blue melanocytic lesions but provide a rationale to use the combination of PI3K/MTOR and MEK1/2 inhibitors against these types of tumors.

Cancer as an ecomolecular disease and a neoplastic consortium

Current anticancer paradigms largely target driver mutations considered integral for cancer cell survival and tumor progression. Although initially successful, many of these strategies are unable to overcome the tremendous heterogeneity that characterizes advanced tumors, resulting in the emergence of resistant disease. Cancer is a rapidly evolving, multifactorial disease that accumulates numerous genetic and epigenetic alterations. This results in wide phenotypic and molecular heterogeneity within the tumor, the complexity of which is further amplified through specific interactions between cancer cells and the tumor microenvironment. In this context, cancer may be perceived as an "ecomolecular" disease that involves cooperation between several neoplastic clones and their interactions with immune cells, stromal fibroblasts, and other cell types present in the microenvironment. This collaboration is mediated by a variety of secreted factors. Cancer is therefore analogous to complex ecosystems such as microbial consortia. In the present article, we comment on the current paradigms and perspectives guiding the development of cancer diagnostics and therapeutics and the potential application of systems biology to untangle the complexity of neoplasia. In our opinion, conceptualization of neoplasia as an ecomolecular disease is warranted. Advances in knowledge pertinent to the complexity and dynamics of interactions within the cancer ecosystem are likely to improve understanding of tumor etiology, pathogenesis, and progression. This knowledge is anticipated to facilitate the design of new and more effective therapeutic approaches that target the tumor ecosystem in its entirety.

ALDH1A3 is epigenetically regulated during melanocyte transformation and is a target for melanoma treatment

Despite the promising targeted and immune-based interventions in melanoma treatment, long-lasting responses are limited. Melanoma cells present an aberrant redox state that leads to the production of toxic aldehydes that must be converted into less reactive molecules. Targeting the detoxification machinery constitutes a novel therapeutic avenue for melanoma. Here, using 56 cell lines representing nine different tumor types, we demonstrate that melanoma cells exhibit a strong correlation between reactive oxygen species amounts and aldehyde dehydrogenase 1 (ALDH1) activity. We found that ALDH1A3 is upregulated by epigenetic mechanisms in melanoma cells compared with normal melanocytes. Furthermore, it is highly expressed in a large percentage of human nevi and melanomas during melanocyte transformation, which is consistent with the data from the TCGA, CCLE and protein atlas databases. Melanoma treatment with the novel irreversible isoform-specific ALDH1 inhibitor [4-dimethylamino-4-methyl-pent-2-ynthioic acid-S methylester] di-methyl-ampal-thio-ester (DIMATE) or depletion of ALDH1A1 and/or ALDH1A3, promoted the accumulation of apoptogenic aldehydes leading to apoptosis and tumor growth inhibition in immunocompetent, immunosuppressed and patient-derived xenograft mouse models. Interestingly, DIMATE also targeted the slow cycling label-retaining tumor cell population containing the tumorigenic and chemoresistant cells. Our findings suggest that aldehyde detoxification is relevant metabolic mechanism in melanoma cells, which can be used as a novel approach for melanoma treatment.

A new diagnostic method based on RT-PCR and CLART technology for non-small cell lung cancer (NSCLC) to detect major EML4-ALK and ROS.1 translocations: CLART CMA ALK and ROS.1

e20045

Background: EML4-ALK and ROS1 translocations represent 3-6% and 1-2% of NSCLC patients, respectively. These patients would benefit for a tyrosine kinase inhibitor therapies. Currently, the gold standard for ALK and ROS.1 detection are break-apart fluorescence in situ hybridization (FISH) or inmunodetection (IHC) of the chimeric fusion proteins. FISH has both high sensitivity and specificity, although often present technical interpretation problems due to signal instability and scoring. IHC is a rapid and low cost technique; however it presents several challenges regarding sensitivity and reproducibility. CLART CMA ALK & ROS.1 kit is based RT-PCR and detection of the amplified product was carried out by a low-density microarray platform: CLART (Clinical Arrays Technology) of major fusion transcripts of EML4-ALK and ROS.1 translocations ( V1: E13;A20 , V6: E13; ins69;A20 , V2: E20;A20 , V3a: E6:A20 , V3b: E6;ins33 A20 ,V5a: E2;A20 and V5b: E2;ins117A20 for EML4-ALK and SDC4-ROS1 S2;R32/ S2;R34, CD74-ROS1 C6;R34 and SLC34A2-ROS1 S4;R32/S4;R34). Methods: The translocations analysis was performed with CLART CMA ALK & ROS.1 kit. Clinical testing was performed using the RNA extracted from 115 samples of NSCLC patients being 34 patients with translocations detected in ALK or ROS.1 genes and 81 patients without any translocations. The results were cross-checked by comparison to Next GenerationS methodology performed on the PGM platform with the Ion Ampliseq Panel Oncomide Solid Tumor Fusion and the concordance was 95.6%. Results: Analytical sensitivity was assessed using fusion transcripts cloned in recombinant plasmids. Results ranged from 10 to 100 copies/5µl of recombinant plasmids. The analysis of 115 clinical samples allowed establishing the diagnostic sensitivity and specificity in 90.9-100% and 99-100% respectively. Conclusions: CLART CMA ALK & ROS.1 emerges as a suitable alternative of FISH/IHQ for diagnosis of the most common translocations in EML4-ALK and ROS.1 genes in NSCLC samples and therefore selecting patients that would best benefit from a target therapy.

Noninvasive EGFR testing in plasma circulating free DNA (cfDNA) by a new diagnostic method to detect point mutations, deletions and insertions associated to non small cell lung cancer: CLART CMA EGFR LB

e20008

Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are current treatments for advanced non-small cell lung cancer (NSCLC) with activating EGFR gene mutations. Histological samples are the standard tumor materials for EGFR mutation analysis. However, the accessibility of tumor samples is not always possible in advanced NSCLC patients. Moreover, a high percentage of EGFR mutated NSCLC patients will develop resistance to EGFR-TKIs such as T790M mutation. CLART CMA EGFR LB is a novel diagnostic assay able to detect 39 high-prevalence mutations associated with sensitivity or resistance to tyrosine kinase inhibitor treatment. Methods: A highly sensitive and specific method was developed for detection of EGFR mutations (G719X, T790M, L858R, L861Q, insertions in exon 20, and deletions in exon 19) in plasma samples (cfDNA). CLART CMA EGFR LB is based on a preamplification step with a multiplex ARMS-PCR and microarray detection system. Clinical testing was performed using 51 clinical plasma samples: 27 contained L858R, T790M, and deletions in exon 19; 24 contained wild type alleles. 20 samples were cross checked by next generation sequencing performed on the PGM platform (Ion Ampliseq™ Custom, deep-coverage 15000x). Results: Analytical sensitivity was assessed using recombinant plasmids, results ranged between 10-1000 copies/5µl for all mutations. cfDNA from cell lines with the mutations L858R, T790M and deletions in exon 19 at different frequencies (cfDNA Reference Standard, Horizon) were assessed. The system was able to detect the mutations present in a frequency of 2%. The analysis of 51 samples allowed establishing the diagnostic sensitivity and specificity in 93.33% and 100% respectively. CLART CMA EGFR LB showed similar analytical and diagnostic sensitivity than NGS for detecting L858R, T790M and deletions in exon 19. Conclusions: Our data support the use of CLART CMA EGFR LB for clinical testing prior to the selection of the appropriate treatment in NSCLC, monitoring the patient evolution and the emergence of resistance mutations such as T790M in plasma samples.

Survival determinants with matched targeted therapies in BRAF mutant metastatic colorectal cancer (mCRC)

649

Background: BRAF mutation (mt) occurs in 5-8% of mCRC and is associated with poor prognosis. Matched targeted therapies for this population are increasingly available in clinical trials. Methods: From Nov 2010 to June 2015, a total of 32 chemorefractory BRAF mt mCRC patients (pts) were enrolled in phase I trials with anti-BRAF matched therapy at Vall d´Hebron Institute of Oncology. BRAF mt was determined by real-time PCR (50%), mass spectrometry (Sequenom, 28%) or next-generation sequencing (Amplicon MiSeq, 22%). All demographic, treatment and survival data were retrospectively analyzed. Results: Median age was 60.4 years (range 42.8-73.5), 62% had right-sided CRC primaries and 59% were stage IV at diagnosis. Median treatment lines before matched therapy was 2 (range 1-4). Co-existing RNFA43, PI3KCA and GNAS mt were found in 4, 2 and 1 pts, respectively. Median time from diagnosis to start of anti-BRAF therapy was 18.6 months (m) (CI95% 14-36) and median time from diagnosis of mCRC to death was 28.4m (CI95% 25-50). A total of 41 anti-BRAF matched therapies were delivered, 9 pts received more than 1 regimen. BRAF inhibitor (inh) monotherapy was delivered in 34% of cases; BRAF plus MEK/EGFR/WNT/PI3K/CDK inh doublets or triplets to 37% and 29% pts, respectively. Survival from start of anti-BRAF to death was 8.9m (CI95% 7-15), without significant differences if 1 or more than 1 anti-BRAF regimen was given (HR: 0.82, p=0.6). Partial responses were observed in 7 cases (17%, 4 doublets and 3 triplets) and complete response in 2 cases (5%, 1 doublet and 1 triplet). Median time on treatment (ToT) with anti-BRAF therapy was 2.83m (CI95% 2-5.5). Of note, ToT was significantly longer for triplets compared to mono/doublets: 5.5m (CI95% 2.7-not reached) vs. 1.9m (CI95% 1.6-3.7; HR: 0.46 [CI95% 0.2-1.0], p=0.05). Median BRAFmt allele fraction (adjusted for tumor purity) was 0.25 (0.13-0.68); no correlation with ToT on anti-BRAF therapy was observed (p=0.36). Conclusions: In a selected BRAF mt population enrolled in early trials with anti-BRAF matched therapy at our institution, survival in the metastatic setting was remarkably high. Triplet matched therapies seem to control disease for longer time than mono/doublets.

Abstract 2058: RHOA inactivation enhances Wnt signaling and promotes colorectal cancer

Activation of the small GTPase RHOA has strong oncogenic effects in many tumor types, although its role in colorectal cancer remains unclear. We show that RHOA inactivation contributes to colorectal cancer progression/metastasis, largely through the activation of Wnt/β-catenin signaling. RhoA inactivation in the murine intestine accelerates the tumorigenic process and in human colon cancer cells leads to the redistribution of β-catenin from the membrane to the nucleus and enhanced Wnt/β-catenin signaling, resulting in increased proliferation, invasion and de-differentiation. In mice, RHOA inactivation contributes to colon cancer metastasis and reduced RHOA levels were observed at metastatic sites compared to primary human colon tumors. Therefore, we have identified a new mechanism of activation of Wnt/β-catenin signaling and characterized the role of RHOA as a novel gene with tumor suppressor activity in colorectal cancer. These results constitute a shift from the current paradigm and demonstrate that RHO GTPases can suppress tumor progression and metastasis.

Citation Format: Paulo Rodrigues, Irati Macaya, Sarah Bazzocco, Elena Andretta, Rocco Mazzolini, Higinio Dopeso, Silvia Mateo-Lozano, Josipa Bilic, Fernando Cartón-García, Rocio Nieto, Lucia Suárez-López, Elsa Afonso, Stefania Landolfi, Javier Hernandez-Losa, Kazuto Kobayashi, Santiago Ramón y Cajal, Josep Tabernero, Niall C. Tebbutt, John M. Mariadason, Simo Schwartz Jr, Diego Arango. RHOA inactivation enhances Wnt signaling and promotes colorectal cancer. [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 2058. doi:10.1158/1538-7445.AM2015-2058

Myo5b knockout mice as a model of microvillus inclusion disease

Inherited MYO5B mutations have recently been associated with microvillus inclusion disease (MVID), an autosomal recessive syndrome characterized by intractable, life-threatening, watery diarrhea appearing shortly after birth. Characterization of the molecular mechanisms underlying this disease and development of novel therapeutic approaches is hampered by the lack of animal models. In this study we describe the phenotype of a novel mouse model with targeted inactivation of Myo5b. Myo5b knockout mice show perinatal mortality, diarrhea and the characteristic mislocalization of apical and basolateral plasma membrane markers in enterocytes. Moreover, in transmission electron preparations, we observed microvillus atrophy and the presence of microvillus inclusion bodies. Importantly, Myo5b knockout embryos at day 20 of gestation already display all these structural defects, indicating that they are tissue autonomous rather than secondary to environmental cues, such as the long-term absence of nutrients in the intestine. Myo5b knockout mice closely resemble the phenotype of MVID patients and constitute a useful model to further investigate the underlying molecular mechanism of this disease and to preclinically assess the efficacy of novel therapeutic approaches.

Clinical and molecular characterization of refractory BRAF mutant metastatic colorectal carcinoma (mCRC): Vall d’Hebron Institute of Oncology phase I program cohort

587

Background: BRAF mutation (mt) occurs in 5-8% of mCRC and its role as a negative prognostic factor is well known. The up-front detection of BRAF mt is not standardized beyond the boundaries of research. However, since novel emerging specific therapies are increasingly available in clinical trials, the prior determination of this mutation is now warranted. Methods: From 07/2010 to 01/2014, 581 patients (pts) with advanced refractory mCRCunderwent genetic tumor profiling as part of the VHIO Phase I Trial Molecular Prescreening Program. BRAF mt was determined by Sanger sequencing or multiplex PCR and mass detection (MassARRAY, Sequenom) of 268 frequent hotspots in 25 oncogenes including, KRAS, NRAS, and PIK3CA. PTEN status was also assessed by immunohistochemistry. Results: 581 samples were analyzed detecting BRAF mt in 56 (9.6%). In the BRAF mt population, median age was 61 years (45-80) and 54% had right-sided CRC. Metastatic sites were found at: liver 61%; peritoneum 52%; lung 39%. Median number of standard treatment was 4 (0-8) including cetuximab and/or panitumumab in 73%. BRAF V600E mutation was detected in 53 samples whereas V600K, D594V and D594G were seen in one sample each. PTEN was analyzed in 44.6% of samples resulting in low expression (H-score <50) in 56%. Other co-existing mutations were PIK3KCA H1047R, PIK3CA E545K, NRAS G12V, GNAS R201C and EGFR S768I. 22 pts were enrolled at least in one phase I trial with drugs targeting either BRAF alone (n=12) or combined with anti-EGFR (n=5), MEK (n=2), PI3K (n=1) inhibitors or double MEK/PI3K inhibition (n=2). Partial responses (PR) were seen in 3 pts (2 with BRAF inhibitor and EGFR inhibitor and 1 with BRAF inhibitor as a single agent). Conclusions: BRAF mt mCRC pts in our institution have a similar pattern to other series reported. Notably, PTEN low expression was present in almost half of the samples analyzed and other co-existent mutations in the ERK and PI3K pathways were detected. This observation, coupled with the clinical outcome observed with single agent BRAF inhibition in this population, suggests that these patients may derive greater benefit from dual BRAF and either EGFR, MEK or PI3K inhibition.

mTOR signaling pathway in penile squamous cell carcinoma: pmTOR and peIF4E over expression correlate with aggressive tumor behavior

PURPOSE

Penile squamous cell carcinoma is a rare neoplasm associated with a high risk of metastasis and morbidity. There are limited data on the role of the mTOR signaling pathway in penile squamous cell carcinoma carcinogenesis and tumor maintenance. We assessed a possible role for mTOR signaling pathway activation as a potential predictive biomarker of outcome and a therapeutic target for penile cancer.

MATERIAL AND METHODS

A cohort of 67 patients diagnosed with invasive penile squamous cell carcinoma from 1987 to 2010 who had known HPV status were selected for study. Tissue microarrays were constructed with 67 primary penile squamous cell carcinomas, matched normal tissues and 8 lymph node metastases. Immunohistochemical staining was performed for p53, pmTOR, pERK, p4E-BP1, eIF4E and peIF4E. Expression was evaluated using a semiquantitative H-score on a scale of 0 to 300.

RESULTS

Expression of pmTOR, p4E-BP1, eIF4E and peIF4E was increased in penile tumors compared with matched adjacent normal tissues, indicating activation of the mTOR signaling pathway in penile tumorigenesis. Over expression of pmTOR, peIF4E and p53 was significantly associated with lymph node disease. peIF4E and p53 also correlated with a poor outcome, including recurrence, metastasis or disease specific death. In contrast, pERK and p4E-BP1 were associated with lower pT stages. pmTOR and intense p53 expression was associated with HPV negative tumors.

CONCLUSIONS

Activation of mTOR signaling may contribute to penile squamous cell carcinoma progression and aggressive behavior. Targeting mTOR or its downstream signaling targets, such as peIF4E, may be a valid therapeutic strategy.

C-MYC, HER2, and HER3 expression in localized prostate cancer (PC) treated with radical radiotherapy: Modulation by statins use and correlation with time to progression

e16045

Background: There has been growing interest in the activity of statins (St) in PC patients receiving definitive radiation therapy. The oncogene Ras can be inhibited by HMG-CoA reductase inhibitors that in turn are also able to downregulate Myc. The aim of this study was to correlate St use and progression with the c-Myc, HER2 and HER3 expression in PC treated with radical radiotherapy (RT) with concurrent androgen deprivation. Methods: A total of 85 patients diagnosed with localised PC between 2000 and 2005 were selected for the study. Inmunohistochemical assay on core biopsy of each patient was performed using monoclonal antibodies for c-Myc, HER2 and HER3. The expression was evaluated using a semiquantitative method (Hscore scale: 0 to 300). Clinical and pathological variables were compared between St users and non-users and correlated with expression of c-Myc, HER2 and HER3. St users were defined as patients who had been taking St for at least 2 years before the diagnosis of PC and during follow up. Time to progression (TTP) was analyzed. Results: Mean age was 71 (56-82) years. Median follow-up was 75 months after RT. Twenty-five patients (29.4%) were using St. No statistical differences were found between treatment groups regarding median age, risk category, clinical T stage, Gleason score or median radiation dose. Median Hscore value of c-Myc was 40 (5-210) for St users vs. 72.5 (5-280) for non-users (p = 0.01). Only 8.6% of the cases showed HER2 expression and in those staining was mild intense and focal. Moderate expression of HER3 was observed in 36 cases (41.8%) and no correlation with St users nor with TTP was demonstrated (p=0.8). At the time of analysis, only 13 pts (15.3%) had biochemical relapse (1 low risk, 3 intermediate, and 9 high risk). St use (46.2%) was significantly associated with improved TTP (55 vs. 36.2 months, p = 0.022). Conclusions: Our work implicates a correlation of St use with a significant lower c-Myc expression and improvement in TTP in all groups, regardless the risk. No correlation was reported between HER2 or HER3, TTP and St use.

The European Thoracic Oncology Platform Lungscape project: Clinical outcome data as a basis for molecular correlations in resected non-small cell lung cancer

7514

Background: Lungscape allowed building the largest virtual biobank of radically resected NSCLC with comprehensive annotated clinical data, with the aims of expediting knowledge on biomarkers and facilitating translation of research to the clinic. Methods: 2,403 stage I-III radically resected NSCLC cases from 15 sites with mandatory comprehensive clinical annotations including at least 2 years of follow-up have been collected retrospectively. A systematic data review of every single case was performed. Relapse-free survival (RFS), time to relapse (TTR) and overall survival (OS) have been analyzed overall and by subgroups. Results: Median age of the cohort is 66 years, with 35% women, and respectively 14%, 32% and 49% never, current and former smokers. Histological types included 52% adenocarcinoma, 40% squamous cell carcinoma, and 4.5% large cell carcinoma and some rarer/mixed subtypes. As shown in the Table, median RFS, TTR and OS differ significantly by stage (p<0.001). Stage remained a significant predictor for outcome in the multivariate Cox models in the presence of other potential prognostic factors. Conclusions: This is the first report on the full Lungscape series based on 7th TNM classification on OS, RFS and TTR across clinical and pathological subgroups. This complete clinical dataset, in particular the information on TTR will be invaluable to investigate the impact of molecular characteristics on outcome, allowing refining TNM staging using biomarkers. Ultimately Lungscape will provide a platform for marker-driven trials of novel therapeutics. [Table: see text]

Brush border myosin Ia inactivation in gastric but not endometrial tumors

Brush border Myosin Ia (MYO1A) has been shown to be frequently mutated in colorectal tumors with microsatellite instability (MSI) and to have tumor suppressor activity in intestinal tumors. Here, we investigated the frequency of frameshift mutations in the A8 microsatellite in exon 28 of MYO1A in MSI gastric and endometrial tumors and found a high mutation rate in gastric (22/47; 46.8%) but not endometrial (3/48; 6.2%) tumors. Using a regression model, we show that MYO1A mutations are likely to confer a growth advantage to gastric, but not endometrial tumors. The mutant MYO1A(7A) protein was shown to lose its membrane localization in gastric cancer cells and a cycloheximide-chase assay demonstrated that the mutant MYO1A(7A) protein has reduced stability compared to the wild type MYO1A. Frequent MYO1A promoter hypermethylation was also found in gastric tumors. Promoter methylation negatively correlates with MYO1A mRNA expression in a series of 58 non-MSI gastric primary tumors (Pearson's r = -0.46; p = 0.0003) but not in a cohort of 54 non-MSI endometrial tumors and treatment of gastric cancer cells showing high MYO1A promoter methylation with the demethylating agent 5-aza-2'-deoxycytidine, resulted in a significant increase of MYO1A mRNA levels. We found that normal gastric epithelial cells, but not normal endometrial cells, express high levels of MYO1A. Therefore, when considered together, our findings suggest that MYO1A has tumor suppressor activity in the normal gastric epithelium but not in the normal endometrium and inactivation of MYO1A either genetically or epigenetically may confer gastric epithelial cells a growth advantage.

Amplification of fibroblast growth factor receptor type 1 gene (FGFR1) in samples from 101 NSCLC patients (pts) with squamous cell carcinoma (SCC) histology

7041

Background: The FGFR1 gene is located in the chromosomal region 8p12 and encodes a transmembrane receptor tyrosine kinase. Amplification of FGFR1 has been reported in lung cancer, predominantly in SCC (in up to ~ 20%) and has been considered a potential target for treatment with anti-FGFR1 agents. Different methods and cutoff levels to determine FGFR1 amplification have been reported but as yet no consensus has been reached on standard method. The aim of this study is to assess FGFR1 amplification determined by FISH analysis in a set of samples from 101SCC pts and to explore their clinical features. Methods: Tumor samples from 101SCC pts diagnosed at our institution from August 2007 to August 2011 were screened for FGFR1 amplification by FISH using the ZytoLight SPEC FGFR1/CEN8 probe. FGFR1 was considered FISH positive with a ratio > 2.2 and FISH FGFR1 was polysomic with 3 or more signals in ≥30% of tumor cells, any other result was considered as negative. For exploratory analyses FGFR1 amplification was considered positive if a median of 6 or more gene copies were identified and FISH were polysomic with more than 2 gene copies but less than 6. Results: Pts characteristics: median age 76 yrs (range 45-80), 91% male, 33% current smokers, 67% former smokers, stage: 8% IA/ 15% IB/ 11% IIA/ 11% IIB/ 24% IIIA, 12% IIIB/ 19% IV. With a median follow up of 48 months, the median overall survival was 18 months. FISH FGFR1 was positive (ratio > 2.2) in 7 (6.9%) pts: 6 were male, 4 former smokers. FISH FGFR1 was considered negative but polysomic (3 or more signals in ≥30% of tumor cells) in 43/94 (45%) pts. If we use for FISH positivity a cutoff of 6 or more copies only 3 patients were considered as positive for FGFR1 amplification (2 were also FISH positive by ratio>2.2). All those 5 patients considered FISH negative by gen copy number (but positive by ratio) were polysomic. Conclusions: In our experience FGFR1 amplification detected by FISH isrelatively uncommon in SCC, although a relevant proportion of FGFR1 FISH negative tumors had polysomy. Standarization of methods to determine FGFR1 amplification and the potential clinical significance of the presence of FGFR1 polysomy are needed.

Prognostic significance of PI3K pathway (PI3Kp) dysregulation in metastatic breast cancer (MBC) patients (pts)

566

Background: PI3Kp dysregulation represents a potential target for therapies that are currently being tested in clinical trials. This observational retrospective study aims to evaluate the prognostic implications of PI3Kp dysregulation in MBC. Methods: MBC pts with PI3Kp status assessment from Sep09 to Sep11 were reviewed. PIK3CA mutation status analyzed in paraffin-embedded tissue by DxS PI3K Mutation Test Kit or Sequenom MassARRAY. PTEN status determined by IHC. PI3Kp status: (a) No dysregulation: PIK3CA wt and PTEN normal; (b) PI3Kp dysregulation: PIK3CA mutation (PIK3CAmut) or PTEN low (HScore≤50). Results: 232 MBC pts screened, median age 49.8 (22.9-83.1) and median MBC lines 4 (1-15). Distribution: HR+/HER2- 99 (43%), HER2+ 52 (22%), triple negative 35 (15%), unclassified 46 (20%). Sites of metastasis: visceral 173 (75%), only skin 10 (4%), only bone 49 (21%). PIK3CA status assessed in 174 pts, 53 (22.8%) bearing a mutation (21 exon9, 32 exon20). PTEN status assessed in 229 pts, PTEN low 61 (26.6%). PI3Kp dysregulation in 103/185 pts (55.6%). Time to progression to first line MBC treatment (TTP) and overall survival after MBC diagnosis (OS) are shown. Disease free survival (DFS) and distant-disease free survival (DDFS) in pts initially diagnosed with early breast cancer (n=193) has also been calculated. Conclusions: These results suggest that PI3Kp dysregulation, either by PIK3CA mutation or PTEN low, does not seem to have impact on disease recurrence, response to first line MBC treatment or overall MBC survival.[Table: see text]

Molecular profiling of patients (pts) with colorectal cancer (CRC) and matched targeted therapy (MTA) in phase I clinical trials

3014

Background: Molecular prescreening and biomarker enrichment strategies in Phase 1 trials with targeted therapies are anticipated to improve the outcomes of affected pts. Methods: As part of our personalized oncology program, tumors from pts with advanced chemorefractory CRC were analyzed for specific molecular aberrations (KRAS/ BRAF/ PIK3CA mutations [mut], PTEN and pMET expression) at the Vall d'Hebron Molecular Pathology and Genomics Labs. Those whose tumors were found to have a dysregulation were offered a Phase 1 trial with MTA. Results: During 2010 and 2011, tumor molecular analysis was performed in 254 pts: KRAS mut (80/254, 31.5%), BRAF mut (24/196, 12.2%), PIK3CA mut (15/114, 13.2%), KRAS+PIK3CA mut (9/114, 7.9%), PTEN low (97/183, 53.0% - HSCORE<50; 45/183, 24.6% - PTEN null), KRAS mut + PTEN low (38/138, 20.8%), pMET high (38/64, 59.4% with HSCORE>30). In total, 68 pts (median, age 63 yrs; prior therapies 3), received 82 different matched therapies. Type of MTA: PI3K pathway inh (if PIK3CA mut, n=10; or PTEN low, n=32), MEK+PI3K pathway inh (if KRAS mut, n=10; or BRAF mut, n=1), second-generation anti-EGFR mAbs (if KRAS wild-type, n=11), anti-HGF mAb (if pMET high, n=10), mTOR inh + anti-IGFR-1R mAb (if PTEN low, n=5) and BRAF inh (if BRAF mut, n=3). Median time to treatment failure (TTF) with MTA was 7.9 weeks (CI95%:7.6-8.1) vs. 16.3 weeks (CI95%:13.9-18.7) for their prior systemic antitumor therapy (p<0.001). If prior therapy non-standard (according to NCCN guidelines, n=39), TTF with MTA 7.9 weeks (CI95%:6.8-8.9) vs. TTF with prior therapy 8.7 weeks (CI95%:7.3-10.1). If an approved standard regimen (n=43), TTF with MTA 7.9 weeks (CI95%:7.6-8.1) vs. TTF with prior therapy 21.9 weeks (CI95%:15.0-28.7). Partial response was seen in one pt (1.2%, PI3K inh with PIK3CA mut) and stable disease > 16 weeks in 10 cases (12.2%). Clinical benefit, defined as a TTF ratio ≥ 1.3 (TTF on MTA/ TTF on prior therapy), was seen with 15.9% of the therapies (13/82). Conclusions: Preliminary results suggest that matching chemorefractory CRC patients with targeted agents in early clinical trials based on the current molecular profile does not result in longer TTF compared to their prior therapy.

Spinophilin acts as a tumor suppressor by regulating Rb phosphorylation

The scaffold protein Spinophilin (SPN) is a regulatory subunit of phosphatase1a located at 17q21.33. This region is frequently associated with microsatellite instability and LOH containing a relatively high density of known tumor suppressor genes, including BRCA1. Several linkage studies have suggested the existence of an unknown tumor suppressor gene distal to BRCA1. Spn may be this gene, but the mechanism through which this gene makes its contribution to cancer has not been described. In this study, we aimed to determine how loss of Spn may contribute to tumorigenesis. We explored the contribution of SPN to PP1a-mediated Rb regulation. We found that the loss of Spn downregulated PPP1CA and PP1a activity, resulting in a high level of phosphorylated Rb and increased ARF and p53 activity. However, in the absence of p53, reduced levels of SPN enhanced the tumorigenic potential of the cells. Furthermore, the ectopic expression of SPN in human tumor cells greatly reduced cell growth. Taken together, our results demonstrate that the loss of Spn induces a proliferative response by increasing Rb phosphorylation, which, in turn, activates p53, thereby neutralizing the proliferative response. We suggest that Spn may be the tumor suppressor gene located at 17q21.33 acting through Rb regulation.