Identification of a core EMT signature that separates basal-like breast cancers into partial- and post-EMT subtypes

Epithelial-mesenchymal transition (EMT) is a cellular plasticity program critical for embryonic development and tissue regeneration, and aberrant EMT is associated with disease including cancer. The high degree of plasticity in the mammary epithelium is reflected in extensive heterogeneity among breast cancers. Here, we have analyzed RNA-sequencing data from three different mammary epithelial cell line-derived EMT models and identified a robust mammary EMT gene expression signature that separates breast cancers into distinct subgroups. Most strikingly, the basal-like breast cancers form two subgroups displaying partial-EMT and post-EMT gene expression patterns. We present evidence that key EMT-associated transcription factors play distinct roles at different stages of EMT in mammary epithelial cells.

The expression pattern of pyruvate dehydrogenase kinases predicts prognosis and correlates with immune exhaustion in clear cell renal cell carcinoma

Renal cancer cells constitute a paradigm of tumor cells with a glycolytic reprogramming which drives metabolic alterations favouring cell survival and transformation. We studied the expression and activity of pyruvate dehydrogenase kinases (PDK1-4), key enzymes of the energy metabolism, in renal cancer cells. We analysed the expression, subcellular distribution and clinicopathological correlations of PDK1-4 by immunohistochemistry of tumor tissue microarray samples from a cohort of 96 clear cell renal cell carcinoma (ccRCC) patients. Gene expression analysis was performed on whole tumor tissue sections of a subset of ccRCC samples. PDK2 and PDK3 protein expression in tumor cells correlated with lower patient overall survival, whereas PDK1 protein expression correlated with higher patient survival. Gene expression analysis revealed molecular association of PDK2 and PDK3 expression with PI3K signalling pathway, as well as with T cell infiltration and exhausted CD8 T cells. Inhibition of PDK by dichloroacetate in human renal cancer cell lines resulted in lower cell viability, which was accompanied by an increase in pAKT. Together, our findings suggest a differential role for PDK enzymes in ccRCC progression, and highlight PDK as actionable metabolic proteins in relation with PI3K signalling and exhausted CD8 T cells in ccRCC.

Cost-effectiveness of molecularly matched off-label therapies for end-stage cancer - the MetAction precision medicine study

BACKGROUND

Precision cancer medicine (PCM), frequently used for the expensive and often modestly efficacious off-label treatment with medications matched to the tumour genome of end-stage cancer, challenges healthcare resources. We compared the health effects, costs and cost-effectiveness of our MetAction PCM study with corresponding data from comparator populations given best supportive care (BSC) in two external randomised controlled trials.

METHODS

We designed three partitioned survival models to evaluate the healthcare costs and quality-adjusted life years (QALYs) as the main outcomes. Cost-effectiveness was calculated as the incremental cost-effectiveness ratio (ICER) of PCM relative to BSC with an annual willingness-to-pay (WTP) threshold of EUR 56,384 (NOK 605,000). One-way and probabilistic sensitivity analyses addressed uncertainty.

RESULTS

We estimated total healthcare costs (relating to next-generation sequencing (NGS) equipment and personnel wages, molecularly matched medications to the patients with an actionable tumour target and follow-up of the responding patients) and the health outcomes for the MetAction patients versus costs (relating to estimated hospital admission) and outcomes for the BSC cases. The ICERs for incremental QALYs were twice or more as high as the WTP threshold and relatively insensitive to cost decrease of the NGS procedures, while reduction of medication prices would contribute significantly towards a cost-effective PCM strategy.

CONCLUSIONS

The models suggested that the high ICERs of PCM were driven by costs of the NGS diagnostics and molecularly matched medications, with a likelihood for the strategy to be cost-effective defying WTP constraints. Reducing drug expenses to half the list price would likely result in an ICER at the WTP threshold. This can be an incentive for a public-private partnership for sharing drug costs in PCM, exemplified by ongoing European initiatives.

CLINICALTRIALS.GOV, IDENTIFIER

NCT02142036.

Heterogeneous Expression and Subcellular Localization of Pyruvate Dehydrogenase Complex in Prostate Cancer

Background

Pyruvate dehydrogenase (PDH) complex converts pyruvate into acetyl-CoA by pyruvate decarboxylation, which drives energy metabolism during cell growth, including prostate cancer (PCa) cell growth. The major catalytic subunit of PDH, PDHA1, is regulated by phosphorylation/dephosphorylation by pyruvate dehydrogenase kinases (PDKs) and pyruvate dehydrogenase phosphatases (PDPs). There are four kinases, PDK1, PDK2, PDK3 and PDK4, which can phosphorylate and inactivate PDH; and two phosphatases, PDP1 and PDP2, that dephosphorylate and activate PDH.

Methods

We have analyzed by immunohistochemistry the expression and clinicopathological correlations of PDHA1, PDP1, PDP2, PDK1, PDK2, PDK3, and PDK4, as well as of androgen receptor (AR), in a retrospective PCa cohort of patients. A total of 120 PCa samples of representative tumor areas from all patients were included in tissue microarray (TMA) blocks for analysis. In addition, we studied the subcellular localization of PDK2 and PDK3, and the effects of the PDK inhibitor dichloroacetate (DCA) in the growth, proliferation, and mitochondrial respiration of PCa cells.

Results

We found heterogeneous expression of the PDH complex components in PCa tumors. PDHA1, PDP1, PDK1, PDK2, and PDK4 expression correlated positively with AR expression. A significant correlation of PDK2 immunostaining with biochemical recurrence and disease-free survival was revealed. In PCa tissue specimens, PDK2 displayed cytoplasmic and nuclear immunostaining, whereas PDK1, PDK3 and PDK4 showed mostly cytoplasmic staining. In cells, ectopically expressed PDK2 and PDK3 were mainly localized in mitochondria compartments. An increase in maximal mitochondrial respiration was observed in PCa cells upon PDK inhibition by DCA, in parallel with less proliferative capacity.

Conclusion

Our findings support the notion that expression of specific PDH complex components is related with AR signaling in PCa tumors. Furthermore, PDK2 expression associated with poor PCa prognosis. This highlights a potential for PDH complex components as targets for intervention in PCa.

Serglycin Is Involved in TGF-β Induced Epithelial-Mesenchymal Transition and Is Highly Expressed by Immune Cells in Breast Cancer Tissue

Serglycin is a proteoglycan highly expressed by immune cells, in which its functions are linked to storage, secretion, transport, and protection of chemokines, proteases, histamine, growth factors, and other bioactive molecules. In recent years, it has been demonstrated that serglycin is also expressed by several other cell types, such as endothelial cells, muscle cells, and multiple types of cancer cells. Here, we show that serglycin expression is upregulated in transforming growth factor beta (TGF-β) induced epithelial-mesenchymal transition (EMT). Functional studies provide evidence that serglycin plays an important role in the regulation of the transition between the epithelial and mesenchymal phenotypes, and it is a significant EMT marker gene. We further find that serglycin is more expressed by breast cancer cell lines with a mesenchymal phenotype as well as the basal-like subtype of breast cancers. By examining immune staining and single cell sequencing data of breast cancer tissue, we show that serglycin is highly expressed by infiltrating immune cells in breast tumor tissue.

Novel human melanoma brain metastasis models in athymic nude fox1nu mice: Site-specific metastasis patterns reflecting their clinical origin

BACKGROUND

Malignant melanomas frequently metastasize to the brain, but metastases in the cerebellum are underrepresented compared with metastases in the cerebrum.

METHODS

We established animal models by injecting intracardially in athymic nude fox1nu mice two human melanoma cell lines, originating from a cerebral metastasis (HM19) and a cerebellar metastasis (HM86).

RESULTS

Using magnetic resonance imaging (MRI), metastases were first detected after a mean of 34.5 days. Mean survival time was 59.6 days for the mice in the HM86 group and significantly shorter (43.7 days) for HM19-injected animals (p < 0.001). In the HM86 group, the first detectable metastasis was located in the cerebellum in 15/55 (29%) mice compared with none in the HM19 group (p < 0.001). At sacrifice, cerebellar metastases were found in 34/55 (63%) HM86-injected mice compared with 1/53 (2%) in the HM19-injected (p < 0.001) mice. At that time, all mice in both groups had detectable metastases in the cerebrum. Comparing macroscopic and histologic appearances of the brain metastases with their clinical counterparts, the cell line-based tumors had kept their original morphologic characteristics.

CONCLUSIONS

The present work demonstrates that human brain-metastatic melanoma cells injected intracardially in mice had retained inherent characteristics also in reproducing interaction with subtle microenvironmental brain tissue compartment-specific features. The models offer new possibilities for investigating tumor- and host-associated factors involved in determining tissue specificity of brain metastasis.

Fibroblast Growth Factor 2 Conjugated with Monomethyl Auristatin E Inhibits Tumor Growth in a Mouse Model

Worldwide, cancer is the second leading cause of death. Regardless of the continuous progress in medicine, we still do not have a fully effective anti-cancer therapy. Therefore, the search for new targeted anti-cancer drugs is still an unmet need. Here, we present novel protein–drug conjugates that inhibit tumor growth in a mouse model of human breast cancer. We developed conjugates based on fibroblast growth factor (FGF2) with improved biophysical and biological properties for the efficient killing of cancer cells overproducing fibroblast growth factor receptor 1 (FGFR1). We used hydrophilic and biocompatible PEG4 or PEG27 molecules as a spacer between FGF2 and the toxic agent monomethyl auristatin E. All conjugates exhibited a cytotoxic effect on FGFR1-positive cancer cell lines. The conjugate with the highest hydrodynamic size (42 kDa) and cytotoxicity was found to efficiently inhibit tumor growth in a mouse model of human breast cancer.

Biodistribution of Poly(alkyl cyanoacrylate) Nanoparticles in Mice and Effect on Tumor Infiltration of Macrophages into a Patient-Derived Breast Cancer Xenograft

We have investigated the biodistribution and tumor macrophage infiltration after intravenous injection of the poly(alkyl cyanoacrylate) nanoparticles (NPs): PEBCA (poly(2-ethyl-butyl cyanoacrylate), PBCA (poly(n-butyl cyanoacrylate), and POCA (poly(octyl cyanoacrylate), in mice. These NPs are structurally similar, have similar PEGylation, and have previously been shown to give large variations in cellular responses in vitro. The PEBCA NPs had the highest uptake both in the patient-derived breast cancer xenograft MAS98.12 and in lymph nodes, and therefore, they are the most promising of these NPs for delivery of cancer drugs. High-resolution magic angle spinning magnetic resonance (HR MAS MR) spectroscopy did not reveal any differences in the metabolic profiles of tumors following injection of the NPs, but the PEBCA NPs resulted in higher tumor infiltration of the anti-tumorigenic M1 macrophages than obtained with the two other NPs. The PEBCA NPs also increased the ratio of M1/M2 (anti-tumorigenic/pro-tumorigenic) macrophages in the tumors, suggesting that these NPs might be used both as a vehicle for drug delivery and to modulate the immune response in favor of enhanced therapeutic effects.

Protein Signature Predicts Response to Neoadjuvant Treatment With Chemotherapy and Bevacizumab in HER2-Negative Breast Cancers

PURPOSE

Antiangiogenic therapy using bevacizumab has proven effective for a number of cancers; however, in breast cancer (BC), there is an unmet need to identify patients who benefit from such treatment.

PATIENTS AND METHODS

In the NeoAva phase II clinical trial, patients (N = 132) with large (≥ 25 mm) human epidermal growth factor receptor 2 (HER2)-negative primary tumors were randomly assigned 1:1 to treatment with neoadjuvant chemotherapy (CTx) alone or in combination with bevacizumab (Bev plus CTx). The ratio of the tumor size after relative to before treatment was calculated into a continuous response scale. Tumor biopsies taken prior to neoadjuvant treatment were analyzed by reverse-phase protein arrays (RPPA) for expression levels of 210 BC-relevant (phospho-) proteins. Lasso regression was used to derive a predictor of tumor shrinkage from the expression of selected proteins prior to treatment.

RESULTS

We identified a nine-protein signature score named vascular endothelial growth factor inhibition response predictor (ViRP) for use in the Bev plus CTx treatment arm able to predict with accuracy pathologic complete response (pCR) (area under the curve [AUC] = 0.85; 95% CI, 0.74 to 0.97) and low residual cancer burden (RCB 0/I) (AUC = 0.80; 95% CI, 0.68 to 0.93). The ViRP score was significantly lower in patients with pCR (P < .001) and in patients with low RCB (P < .001). The ViRP score was internally validated on mRNA data and the resultant surrogate mRNA ViRP score significantly separated the pCR patients (P = .016). Similarly, the mRNA ViRP score was validated (P < .001) in an independent phase II clinical trial (PROMIX).

CONCLUSION

Our ViRP score, integrating the expression of nine proteins and validated on mRNA data both internally and in an independent clinical trial, may be used to increase the likelihood of benefit from treatment with bevacizumab combined with chemotherapy in patients with HER2-negative BC.

Protein Kinase C Isozymes Associated With Relapse Free Survival in Non-Small Cell Lung Cancer Patients

INTRODUCTION

Protein expression is deregulated in cancer, and the proteomic changes observed in lung cancer may be a consequence of mutations in essential genes. The purpose of this study was to identify protein expression associated with prognosis in lung cancers stratified by smoking status, molecular subtypes, and EGFR-, TP53-, and KRAS-mutations.

METHODS

We performed profiling of 295 cancer-relevant phosphorylated and non-phosphorylated proteins, using reverse phase protein arrays. Biopsies from 80 patients with operable lung adenocarcinomas were analyzed for protein expression and association with relapse free survival (RFS) were studied.

RESULTS

Spearman's rank correlation analysis identified 46 proteins with significant association to RFS (p<0.05). High expression of protein kinase C (PKC)-α and the phosporylated state of PKC-α, PKC-β, and PKC-δ, showed the strongest positive correlation to RFS, especially in the wild type samples. This was confirmed in gene expression data from 172 samples. Based on protein expression, unsupervised hierarchical clustering separated the samples into four subclusters enriched with the molecular subtypes terminal respiratory unit (TRU), proximal proliferative (PP), and proximal inflammatory (PI) (p=0.0001). Subcluster 2 contained a smaller cluster (2a) enriched with samples of the subtype PP, low expression of the PKC isozymes, and associated with poor RFS (p=0.003) compared to the other samples. Low expression of the PKC isozymes in the subtype PP and a reduced relapse free survival was confirmed with The Cancer Genome Atlas (TCGA) lung adenocarcinoma (LUAD) samples.

CONCLUSION

This study identified different proteins associated with RFS depending on molecular subtype, smoking- and mutational-status, with PKC-α, PKC-β, and PKC-δ showing the strongest correlation.

Targeting Telomerase with an HLA Class II-Restricted TCR for Cancer Immunotherapy

T cell receptor (TCR)-engineered T cell therapy is a promising cancer treatment approach. Human telomerase reverse transcriptase (hTERT) is overexpressed in the majority of tumors and a potential target for adoptive cell therapy. We isolated a novel hTERT-specific TCR sequence, named Radium-4, from a clinically responding pancreatic cancer patient vaccinated with a long hTERT peptide. Radium-4 TCR-redirected primary CD4⁺ and CD8⁺ T cells demonstrated in vitro efficacy, producing inflammatory cytokines and killing hTERT⁺ melanoma cells in both 2D and 3D settings, as well as malignant, patient-derived ascites cells. Importantly, T cells expressing Radium-4 TCR displayed no toxicity against bone marrow stem cells or mature hematopoietic cells. Notably, Radium-4 TCR⁺ T cells also significantly reduced tumor growth and improved survival in a xenograft mouse model. Since hTERT is a universal cancer antigen, and the very frequently expressed HLA class II molecules presenting the hTERT peptide to this TCR provide a very high (>75%) population coverage, this TCR represents an attractive candidate for immunotherapy of solid tumors.

Molecularly matched therapy in the context of sensitivity, resistance, and safety; patient outcomes in end-stage cancer - the MetAction study

Background: In precision cancer medicine, the challenge is to prioritize DNA driver events, account for resistance markers, and procure sufficient information for treatment that maintains patient safety. The MetAction project, exploring how tumor molecular vulnerabilities predict therapy response, first established the required workflow for DNA sequencing and data interpretation (2014-2015). Here, we employed it to identify molecularly matched therapy and recorded outcome in end-stage cancer (2016-2019).Material and methods: Metastatic tissue from 26 patients (16 colorectal cancer cases) was sequenced by the Oncomine assay. The study tumor boards interpreted called variants with respect to sensitivity or resistance to matched therapy and recommended single-agent or combination treatment if considered tolerable. The primary endpoint was the rate of progression-free survival 1.3-fold longer than for the most recent systemic therapy. The objective response rate and overall survival were secondary endpoints.Results: Both common and rare actionable alterations were identified. Thirteen patients were found eligible for therapy following review of tumor sensitivity and resistance variants and patient tolerability. The interventions were inhibitors of ALK/ROS1-, BRAF-, EGFR-, FGFR-, mTOR-, PARP-, or PD-1-mediated signaling for 2-3 cases each. Among 10 patients who received treatment until radiologic evaluation, 6 (46% of the eligible cases) met the primary endpoint. Four colorectal cancer patients (15% of the total study cohort) had objective response. The only serious adverse event was a transient colitis, which appeared in 1 of the 2 patients given PD-1 inhibitor with complete response. Apart from those two, overall survival was similar for patients who did and did not receive study treatment.Conclusions: The systematic MetAction approach may point forward to a refined framework for how to interpret the complexity of sensitivity versus resistance and patient safety that resides in tumor sequence data, for the possibly improved outcome of precision cancer medicine in future studies. ClinicalTrials.gov, identifier: NCT02142036.

Drug-Loaded Photosensitizer-Chitosan Nanoparticles for Combinatorial Chemo- and Photodynamic-Therapy of Cancer

In this study we have developed biodegradable polymeric nanoparticles (NPs) containing the cytostatic drugs mertansine (MRT) or cabazitaxel (CBZ). The NPs are based on chitosan (CS) conjugate polymers synthesized with different amounts of the photosensitizer tetraphenylchlorin (TPC). These TPC–CS NPs have high loading capacity and strong drug retention due to π–π stacking interactions between the drugs and the aromatic photosensitizer groups of the polymers. CS polymers with 10% of the side chains containing TPC were found to be optimal in terms of drug loading capacity and NP stability. The TPC–CS NPs loaded with MRT or CBZ displayed higher cytotoxicity than the free form of these drugs in the breast cancer cell lines MDA-MB-231 and MDA-MB-468. Furthermore, light-induced photochemical activation of the NPs elicited a strong photodynamic therapy effect on these breast cancer cells. Biodistribution studies in mice showed that most of the TPC–CS NPs accumulated in liver and lungs, but they were also found to be localized in tumors derived from HCT-116 cells. These data suggest that the drug-loaded TPC–CS NPs have a potential in combinatory anticancer therapy and as contrast agents.

Paclitaxel-loaded biodegradable ROS-sensitive nanoparticles for cancer therapy

Background

Reactive oxygen species (ROS), such as hydrogen peroxide and superoxide, trigger biodegradation of polymer-based nanoparticles (NPs) bearing pinacol-type boronic ester groups. These NPs may selectively release their cargo, in this case paclitaxel (PTX), at the high levels of ROS present in the intracellular environment of inflamed tissues and most tumors.

Purpose

The main objective was to determine anti-tumor efficacy of PTX-loaded ROS-sensitive NPs and to examine whether macrophage infiltration had any impact on treatment efficacy.

Methods

NPs were synthesized and their characteristics in the presence of H₂O₂ were demonstrated. Both confocal microscopy as well as flow cytometry approaches were used to determine degradation of ROS-sensitive NPs. HeLa cells were cultured in vitro and used to establish tumor xenografts in nude mice. In vivo experiments were performed to understand toxicity, biodistribution and anti-tumor efficacy of the NPs. Moreover, we performed immunohistochemistry on tumor sections to study infiltration of M1 and M2 subsets of macrophages.

Results

We demonstrated that PTX delivered in NPs containing a ROS-sensitive polymer exhibits a better anti-tumor efficacy than PTX in NPs containing ROS-non-sensitive polymer, free PTX or Abraxane^® (nab-PTX). The biodistribution revealed that ROS-sensitive NPs exhibit retention in liver, spleen and lungs, suggesting a potential to target cancer metastasizing to these organs. Finally, we demonstrated a correlation between infiltrated macrophage subsets and treatment efficacy, possibly contributing to the efficient anti-tumor effects.

Conclusion

Treatment with ROS-sensitive NPs containing PTX gave an improved therapeutic effect in HeLa xenografts than their counterpart, free PTX or nab-PTX. Our data revealed a correlation between macrophage infiltration and efficiency of the different antitumor treatments, as the most effective NPs resulted in the highest infiltration of the anti-tumorigenic M1 macrophages.

Glutamine to proline conversion is associated with response to glutaminase inhibition in breast cancer

INTRODUCTION

Glutaminase inhibitors target cancer cells by blocking the conversion of glutamine to glutamate, thereby potentially interfering with anaplerosis and synthesis of amino acids and glutathione. The drug CB-839 has shown promising effects in preclinical experiments and is currently undergoing clinical trials in several human malignancies, including triple-negative breast cancer (TNBC). However, response to glutaminase inhibitors is variable and there is a need for identification of predictive response biomarkers. The aim of this study was to determine how glutamine is utilized in two patient-derived xenograft (PDX) models of breast cancer representing luminal-like/ER+ (MAS98.06) and basal-like/triple-negative (MAS98.12) breast cancer and to explore the metabolic effects of CB-839 treatment.

EXPERIMENTAL

MAS98.06 and MAS98.12 PDX mice received CB-839 (200 mg/kg) or drug vehicle two times daily p.o. for up to 28 days (n = 5 per group), and the effect on tumor growth was evaluated. Expression of 60 genes and seven glutaminolysis key enzymes were determined using gene expression microarray analysis and immunohistochemistry (IHC), respectively, in untreated tumors. Uptake and conversion of glutamine were determined in the PDX models using HR MAS MRS after i.v. infusion of [5-¹³C] glutamine when the models had received CB-839 (200 mg/kg) or vehicle for 2 days (n = 5 per group).

RESULTS

Tumor growth measurements showed that CB-839 significantly inhibited tumor growth in MAS98.06 tumors, but not in MAS98.12 tumors. Gene expression and IHC analysis indicated a higher proline synthesis from glutamine in untreated MAS98.06 tumors. This was confirmed by HR MAS MRS of untreated tumors demonstrating that MAS98.06 used glutamine to produce proline, glutamate, and alanine, and MAS98.12 to produce glutamate and lactate. In both models, treatment with CB-839 resulted in accumulation of glutamine. In addition, CB-839 caused depletion of alanine, proline, and glutamate ([1-13C] glutamate) in the MAS98.06 model.

CONCLUSION

Our findings indicate that TNBCs may not be universally sensitive to glutaminase inhibitors. The major difference in the metabolic fate of glutamine between responding MAS98.06 xenografts and non-responding MAS98.12 xenografts is the utilization of glutamine for production of proline. We therefore suggest that addiction to proline synthesis from glutamine is associated with response to CB-839 in breast cancer. The effect of glutaminase inhibition in two breast cancer patient-derived xenograft (PDX) models. ¹³C HR MAS MRS analysis of tumor tissue from CB-839-treated and untreated models receiving ¹³C-labeled glutamine ([5-¹³C] Gln) shows that the glutaminase inhibitor CB-839 is causing an accumulation of glutamine (arrow up) in two PDX models representing luminal-like breast cancer (MAS98.06) and basal-like breast cancer (MAS98.12). In MAS98.06 tumors, CB-839 is in addition causing depletion of proline ([5-¹³C] Pro), alanine ([1-¹³C] Ala), and glutamate ([1-¹³C] Glu), which could explain why CB-839 causes tumor growth inhibition in MAS98.06 tumors, but not in MAS98.12 tumors.

p38 MAPK activation through B7-H3-mediated DUSP10 repression promotes chemoresistance

Immunoregulatory protein B7-H3 is involved in the oncogenic and metastatic potential of cancer cells, as well as in drug resistance. Resistance to conventional chemotherapy is an important aspect of melanoma treatment, and a better understanding of how B7-H3 enhances drug resistance may lead to the development of more effective therapies. We investigated the in vitro and in vivo sensitivity of chemotherapeutic agents dacarbazine (DTIC) and cisplatin in sensitive and drug resistant melanoma cells with knockdown expression of B7-H3. We found that knockdown of B7-H3 increased in vitro and in vivo sensitivity of melanoma cells to the chemotherapeutic agents dacarbazine (DTIC) and cisplatin, in parallel with a decrease in p38 MAPK phosphorylation. Importantly, in B7-H3 knockdown cells we observed an increase in the expression of dual-specific MAP kinase phosphatase (MKP) DUSP10, a MKP known to dephosphorylate and inactivate p38 MAPK. DUSP10 knockdown by siRNA resulted in a reversion of the increased DTIC-sensitivity seen in B7-H3 knockdown cells. Our findings highlight the potential therapeutic benefit of combining chemotherapy with B7-H3 inhibition, and indicate that B7-H3 mediated chemoresistance in melanoma cells is driven through a mechanism involving DUSP10-mediated inactivation of p38 MAPK.

Responsiveness to PD-1 Blockade in End-Stage Colon Cancer with Gene Locus 9p24.1 Copy-Number Gain

Most patients whose large bowel cancer has spread to other organs do not respond to immune therapy. We detected a rare gene mutation, termed 9p24.1 copy-number gain (CNG), in an otherwise incurable colorectal cancer that provoked an immune therapy response. We identified this gene mutation by gene-panel sequencing of DNA from a liver metastasis biopsy from a patient who had disease refractory to standard therapies. Following immune checkpoint blockade (ICB) with pembrolizumab (anti-PD-1), the patient experienced conversion of the tumor phenotype from one with epithelial features to that of an inflamed microenvironment, detected by high-resolution RNA sequencing. Circulating tumor DNA disappeared over the first weeks of therapy. As assessed by standard radiographic measurement, the patient had a partial response that was durable. This patient's response may support the use of histology-agnostic ICB in solid tumors that carry the rare 9p24.1 CNG.

Combining the oncolytic peptide LTX-315 with doxorubicin demonstrates therapeutic potential in a triple-negative breast cancer model

Background

Immunochemotherapy, the combined use of immunotherapy and chemotherapy, has demonstrated great promise in several cancers. LTX-315 is an oncolytic peptide with potent immunomodulatory properties designed for the local treatment of solid tumors. By inducing rapid immunogenic cell death through the release of danger-associated molecular pattern molecules (DAMPs), LTX-315 is capable of reshaping the tumor microenvironment, turning “cold” tumors “hot” through a significant increase in tumor-infiltrating lymphocytes.

Methods

We investigated the potential of LTX-315 to be used in combination with standard-of-care chemotherapy (doxorubicin, brand name CAELYX®) against triple-negative breast cancer in an orthotopic 4 T1 mammary fat pad model. Tumor growth curves were compared using one-way ANOVA analysis of variance and Tukey’s multiple comparisons test, and animal survival curves were compared using the log-rank (Mantel-Cox) test. We considered p values ≤0.05 to indicate statistical significance.

Results

We found that LTX-315 displayed a strong additive antitumoral effect when used in combination with CAELYX®, and induced immune-mediated changes in the tumor microenvironment, followed by complete regression in the majority of animals treated. Furthermore, imaging techniques and histological examination showed that the combination induced strong local necrosis, followed by an increase in the infiltration of CD4+ and CD8+ immune cells into the tumor parenchymal tissue.

Conclusions

Our data demonstrate that LTX-315 is a promising combination partner with CAELYX® for the treatment of triple-negative breast cancer.

Cabazitaxel-loaded Poly(2-ethylbutyl cyanoacrylate) nanoparticles improve treatment efficacy in a patient derived breast cancer xenograft

The effect of poly(2-ethyl-butyl cyanoacrylate) nanoparticles containing the cytotoxic drug cabazitaxel was studied in three breast cancer cell lines and one basal-like patient-derived xenograft model grown in the mammary fat pad of immunodeficient mice. Nanoparticle-encapsulated cabazitaxel had a much better efficacy than similar concentrations of free drug in the basal-like patient-derived xenograft and resulted in complete remission of 6 out of 8 tumors, whereas free drug gave complete remission only with 2 out of 9 tumors. To investigate the different efficacies obtained with nanoparticle-encapsulated versus free cabazitaxel, mass spectrometry quantification of cabazitaxel was performed in mice plasma and selected tissue samples. Nanoparticle-encapsulated drug had a longer circulation time in blood. There was approximately a three times higher drug concentration in tumor tissue 24 h after injection, and two times higher 96 h after injection of nanoparticles with drug compared to the free drug. The tissue biodistribution obtained after 24 h using mass spectrometry analyses correlates well with biodistribution data obtained using IVIS® Spectrum in vivo imaging of nanoparticles labeled with the fluorescent substance NR668, indicating that these data also are representative for the nanoparticle distribution. Furthermore, immunohistochemistry was used to estimate infiltration of macrophages into the tumor tissue following injection of nanoparticle-encapsulated and free cabazitaxel. The higher infiltration of anti-tumorigenic versus pro-tumorigenic macrophages in tumors treated with the nanoparticles might also contribute to the improved effect obtained with the nanoparticle-encapsulated drug. Tumor infiltration of pro-tumorigenic macrophages was four times lower when using nanoparticles containing cabazitaxel than when using particles without drug, and we speculate that the very good therapeutic efficacy obtained with our cabazitaxel-containing particles may be due to their ability to reduce the level of pro-tumorigenic macrophages in the tumor. In summary, encapsulation of cabazitaxel in poly(2-ethyl-butyl cyanoacrylate) nanoparticles seems promising for treatment of breast cancer.

Levels and prognostic impact of circulating markers of inflammation, endothelial activation and extracellular matrix remodelling in patients with lung cancer and chronic obstructive pulmonary disease

Background

The development of both chronic obstructive pulmonary disease (COPD) and lung cancer (LC) is influenced by smoking related chronic pulmonary inflammation caused by an excessive innate immune response to smoke exposure. In addition, the smoking induced formation of covalent bonds between the carcinogens and DNA and the accumulation of permanent somatic mutations in critical genes are important in the carcinogenic processes, and can also induce inflammatory responses.

How chronic inflammation is mirrored by serum markers in COPD and LC and if these markers reflect prognosis in patients with LC is, however, largely unknown.

Methods

Serum levels of 18 markers reflecting inflammation, endothelial activation and extracellular matrix remodelling were analysed in 207 patients with non-small lung carcinoma (NSCLC) before surgery and 42 COPD patients. 56% of the LC patients also suffered from COPD. The serum samples were analysed by enzyme immunoassays.

Results

Serum levels of OPG, PTX3, AXL, ALCAM, sCD163, CD147, CatS and DLL1 were significantly higher in patients with COPD as compared to patients with LC. High sTNFR1 levels were associated with improved progression free survival (PFS) and overall survival (OS) in LC patients with (PFS hazard ratio (HR) 0.49, OS HR 0.33) and without COPD (OS HR 0.30). High levels of OPG were associated with improved PFS (HR 0.17) and OS (HR 0.14) for LC with COPD. CRP was significantly associated with overall survival regardless of COPD status.

Conclusion

Several markers reflecting inflammation, endothelial activation and extracellular matrix remodelling are elevated in serum from patients with COPD compared to LC patients. Presence of COPD might influence the levels of circulating biomarkers. Some of these markers are also associated with prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4659-0) contains supplementary material, which is available to authorized users.

Abstract 4705: The novel oncolytic peptide, DTT-304, induces regression of colorectal cancer tumors in vivo

Colorectal cancer (CRC) is the third most common cancer in the world, and approximately 50% of the patients develop liver metastasis, which is a major cause of disease mortality. New drugs and treatment options are therefore necessary to improve the survival of these patients. Lately, different types of immunotherapy, such as check point inhibitors, have shown great promise in the treatment of metastatic cancer, although for most patients with CRC the efficacy has been restricted to cases with microsatellite instable disease. Another novel immunotherapeutic strategy is oncolytic immunotherapy, which has been shown to cause immunogenic cancer cell death. Following cancer cell lysis, damage associated molecular patterns (DAMPs) are released, which are recognized by immune cell receptors. Pro-inflammatory responses will then be triggered to induce release of tumor specific antigens that are presented to the immune system, leading to tumor-specific immune responses.

In the present study, we have investigated the efficacy of a novel oncolytic peptide, DTT-304, using two mouse models. Subcutaneous tumors were established in Balb c mice using the cell line CT26 and in C57Bl6 mice using the cell line MC38, both murine CRC cell lines. In both models, intra-tumoral injection of the peptide induced tumor necrosis and complete regression a few days after initiation of treatment, thus showing the potential of this peptide for use in colorectal cancer.

In ongoing experiments we are investigating if the peptide has the potential to induce long lasting protective tumor-specific immune responses by re-challenging previously treated mice with the same cell line in a liver metastasis model. In addition, the possibility of treating liver tumors by direct peptide injection will be investigated.

Citation Format: Karianne G. Fleten, Johannes J. Eksteen, Brynjar Mauseth, Ketil Camilio, Øystein Rekdal, Meng Yu Wang, Gunhild M. Mælandsmo, Kjersti Flatmark. The novel oncolytic peptide, DTT-304, induces regression of colorectal cancer tumors in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4705.

Enhanced targeting of triple-negative breast carcinoma and malignant melanoma by photochemical internalization of CSPG4-targeting immunotoxins

Triple-negative breast cancer (TNBC) and malignant melanoma are highly aggressive cancers that widely express the cell surface chondroitin sulfate proteoglycan 4 (CSPG4/NG2). CSPG4 plays an important role in tumor cell growth and survival and promotes chemo- and radiotherapy resistance, suggesting that CSPG4 is an attractive target in cancer therapy. In the present work, we applied the drug delivery technology photochemical internalization (PCI) in combination with the novel CSPG4-targeting immunotoxin 225.28-saporin as an efficient and specific strategy to kill aggressive TNBC and amelanotic melanoma cells. Light-activation of the clinically relevant photosensitizer TPCS2a (fimaporfin) and 225.28-saporin was found to act in a synergistic manner, and was superior to both PCI of saporin and PCI-no-drug (TPCS2a + light only) in three TNBC cell lines (MDA-MB-231, MDA-MB-435 and SUM149) and two BRAFV600E mutated malignant melanoma cell lines (Melmet 1 and Melmet 5). The cytotoxic effect was highly dependent on the light dose and expression of CSPG4 since no enhanced cytotoxicity of PCI of 225.28-saporin compared to PCI of saporin was observed in the CSPG4-negative MCF-7 cells. The PCI of a smaller, and clinically relevant CSPG4-targeting toxin (scFvMEL-rGel) validated the CSPG4-targeting concept in vitro and induced a strong inhibition of tumor growth in the amelanotic melanoma xenograft A-375 model. In conclusion, the combination of the drug delivery technology PCI and CSPG4-targeting immunotoxins is an efficient, specific and light-controlled strategy for the elimination of aggressive cells of TNBC and malignant melanoma origin. This study lays the foundation for further preclinical evaluation of PCI in combination with CSPG4-targeting.

Abstract A101: The MetAction trial: long-lasting responses to molecularly matched therapy in end-stage cancer

Background: The first phase of the MetAction trial established the required diagnostic infrastructure, implemented security-approved systems for handling of sensitive information, educated the Trial Team within the context of tumor boards, and estimated costs of the initiative within public health services. The endeavor enabled expedited and safe mutation profiling of metastatic tumors in order to offer molecularly matched medication for end-stage cancer (Ree et al., ESMO Open 2017;2:e000158). The aim of the second trial phase was to investigate the utility of the MetAction pipeline in clinical practice. Procedures: An eligible patient with end-stage metastatic disease from any origin had been on the previous line of systemic therapy for 6 or more weeks with radiologic evaluation intervals of 6-12 weeks and disease progression according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Biopsy-sampled metastatic tissue was analyzed by DNA sequencing (Ion Oncomine™ Comprehensive Panel), where called variants were filtered prior to assessment and prioritization, supplemented with fluorescence in situ hybridization to cover relevant biomarkers. The Molecular Tumor Board interpreted the findings within the likelihood of signaling pathway activity, for the sequential Clinical Tumor Board to conclude on potential systemic tumor-directed medication. On study therapy, radiologic work-up was performed every 8 weeks. The primary objective was to compare progression-free survival (PFS) on study treatment, termed Period-B, with PFS for the most recent therapy, termed Period-A. If Period-B/Period-A was ≥1.3, the study therapy was deemed to be of benefit. The incidence of diagnostic adverse events and treatment-related grade 3-5 Common Terminology Criteria for Adverse Events (CTCAE) toxicities was secondary end points. Results: 26 patients were enrolled. Biopsy procedures were undertaken at lung or pleural sites (6 cases), liver or peritoneal sites (19 cases), and an inguinal lymph node (1 case), and did not cause adverse events. Histologic entities were 18 adenocarcinomas (AC), 2 undifferentiated carcinomas, 1 case each of cholangiocarcinoma and squamous cell carcinoma, and 4 different sarcoma entities. 13 patients were found eligible for off-label use of molecularly matched therapy (inhibitor of ALK-, BRAF-, EGFR-, FGFR-, mTOR-, PARP-, ROS1-, or PD-1-mediated signaling). Among the 10 individuals who received study treatment until radiologic evaluation, 5 met the primary end point. The patient with cholangiocarcinoma and a patient with rectal AC primaries, both given crizotinib, obtained Period-B/Period-A outcome slightly better than 1.3. Notably, 3 patients with colon AC primaries, receiving either a combination of panitumumab with vemurafenib or chemotherapy or single-agent pembrolizumab, obtained long-lasting responses. In addition, 1 colon AC patient receiving pembrolizumab with RECIST progression (i.e., primary end point failure) before a long-lasting response to off-protocol continuation, reported CTCAE grade 3 toxicity (a colitis event that immediately resolved on high-dose prednisolone). Conclusion: MetAction procedures and treatments were safe. 15% (4/26) of patients with progressing end-stage cancer had the disease course substantially reversed by this biomarker-directed therapy approach.

Citation Format: Anne Hansen Ree, Kjersti Flatmark, Vigdis Nygaard, Daniel Heinrich, Kjetil Boye, Svein Dueland, Vegard Nygaard, Eivind Hovig, Klaus Beiske, Marius Lund-Iversen, Vivi A. Flørenes, Christin Johansen, Inger Riise Bergheim, Menaka Sathermugathevan, Sigve Nakken, Gry A. Geitvik, Ole C. Lingjærde, Anne-Lise Børresen-Dale, Hege G. Russnes, Gunhild M. Mælandsmo. The MetAction trial: long-lasting responses to molecularly matched therapy in end-stage cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A101.

Abstract 1752: Immune-related gene signatures in colorectal liver metastases: Exposing an opportunity for immune modulating therapy

Colorectal cancer (CRC) is one of the most common cancers and one of the leading causes of cancer death in the Western world. Up to 50% of patients with CRC develop metastatic disease and the liver is the most common site. The recently identified consensus molecular subtypes (CMS1-4) based on analyses of primary CRC have prognostic and therapeutic implications, but it is unclear whether these molecular subtypes are valid for metastatic disease. In this study, characterisation of CRC liver metastases (CLM) was performed at multiple molecular levels to identify characteristics relevant to metastatic disease. Molecular stratification of a defined metastatic CRC cohort may yield results of clinical relevance and novel treatment opportunities.

Surgically resected CLM and tumor-adjacent liver tissue from 46 patients were analysed for the presence of mutations (targeted deep sequencing), genome-wide copy number alterations (CNA), and transcription profiled. Molecular profiles of CLM and tumor-adjacent liver tissues were analyzed and associations with clinicopathological features and outcome were investigated. We found oncogenic mutations in all except one tumor. Both mutation and CNA profiles were similar to profiles reported for primary CRC. A CMS classifier tool applied to gene expression data, revealed the cohort to be highly enriched for CMS2. Unsupervised clustering based on genes with highly variable expression identified a 55-gene cluster that segregated the samples into two subgroups. The segregation pattern was replicated in relevant publicly available data sets, but the clinical significance of this observation is not evident. The 55 genes were associated with lipid metabolic and immune-related functions, revealing a role of the tumor-host microenvironment. The engagement of the immune system was further underlined by analyzing subgroups defined by neoadjuvant chemotherapy (NACT) administration, which revealed altered expression of inflammatory mediators and immune regulatory genes. The majority of treated patients had received Oxaliplatin based chemotherapy.

The uniform classification of CLM by CMS may reflect the patient composition in our cohort, but may also indicate that novel class discovery approaches need to be explored to uncover clinically useful molecular stratification of CLM. Identified immune-related gene expression signatures associated with molecular and clinical features underline the integration and importance of the immune interactome in resectable CLM. Specifically, the transcriptomic snapshot of NACT exposed CLM revealed altered genes associated with immunogenic cell death but also immune suppression. These results point to rational exploration of immune-modulating strategies in CLM in combination with NACT to increase efficacy and broaden treatment opportunities for this patient group.

Citation Format: Vigdis Nygaard, Vegar J. Dagenborg, Olga Østrup, Einar A. Rødland, Veronica Skarpeteig, Laxmi Silwal-Pandit, Krzysztof Grzyb, Audun E. Berstad, Åsmund A. Fretland, Gunhild M. Mælandsmo, Anne-Lise Børresen-Dale, Anne H. Ree, Bjørn Edwin, Kjersti Flatmark. Immune-related gene signatures in colorectal liver metastases: Exposing an opportunity for immune modulating therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1752. doi:10.1158/1538-7445.AM2017-1752

Abstract 4329: Targetable nodes in fibroblast-supported melanoma cells that show resistance to BRAF inhibitors

Metastatic melanoma is notorious for the ability to change its phenotype in response to signals from the microenvironment, which might influence how melanoma responds to therapy. We have disclosed an association between fibroblast-induced phenotypic alterations in melanoma and resistance to the mutated BRAF inhibitor vemurafenib (BRAFi). This signifies the need to find other targets than BRAF to eliminate stroma-influenced melanoma cells. To approach this challenge, we performed proteomic analysis and cancer drug sensitivity screening, comparing fibroblast-supported versus non-supported melanoma cells. We showed that the effect of fibroblasts was critically dependent on cell-cell proximity, where melanoma cells get trapped in a fibronectin network, produced by adjacent fibroblasts. In such environment, melanoma cells down-regulate melanocytic programs (MITF-driven), gain mesenchymal features (AXL, PDGFR, fibronectin) and activate stress/inflammatory-response signaling pathways (JNK and STAT3). Altogether, this indicates fibroblast-induced melanoma transition to a de-differentiated, mesenchymal-like, pro-inflammatory phenotype. Melanoma cells with such phenotype were less responsive to BRAF/MAPK inhibitors and a number of other targeted drugs. However, they showed enhanced sensitivity to PI3K/mTOR inhibitors and, particularly, an inhibitor of GSK3b, stimulating Wnt/b-catenin signaling. Further, we employed flow cytometry to measure the levels of Ki67 and pS6 in single melanoma cells upon different conditions/treatments. Such analysis allowed discrimination of cell subpopulations representing a proliferative and a quiescent cellular state, and nicely reflected the influence of the tested drugs in the presence or absence of fibroblasts. We observed a subpopulation of proliferative pS6high/Ki67high melanoma cells, which remained after treatment with BRAFi if fibroblasts were present. This, fibroblast-protected BRAFi-resistant cell subpopulation, could be reduced/eliminated by PI3K or GSK3b inhibitors, verifying PI3K/GSK3 as potential targets in fibroblast-rich tumors. Currently, we are using mass cytometry (CyTOF) to further characterize cell subpopulations with respect to multiple markers related to cell signaling and immune interactions. Preliminary results indicate that not only signaling protein levels, but also levels of immunoregulatory proteins are altered in melanoma cells that get support from the fibroblasts. In conclusion, we demonstrate fibroblast-induced melanoma switching to a mesenchymal-like pro-inflammatory phenotype, which favors melanoma resistance to BRAF inhibitors, but sensitizes to inhibitors of PI3K/mTOR-associated signaling. CyTOF-analysis of complex tumor-stroma cell systems is used to search for additional strategies to target stroma-supported melanoma cells, either at the level of signaling, or immune interactions.

Citation Format: Kotryna Seip, Marco V. Haselager, Kjetil Jørgensen, Marco Albrecht, Mads H. Haugen, Eivind Valen Egeland, Philippe Lucarelli, Thomas Sauter, Olav Engebraaten, Gunhild M. Mælandsmo, Lina Prasmickaite. Targetable nodes in fibroblast-supported melanoma cells that show resistance to BRAF inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4329. doi:10.1158/1538-7445.AM2017-4329

Abstract 1660: Humanization of patient derived xenograft (PDX) cancer model mice with peripheral blood mononuclear cells (PBMCs)

Immunocompetent transgenic mouse models have for decades served as valuable tools to address the effect of oncogenes and tumor suppressors. Immunodeficient mice have been used to establish patient derived xenograft (PDX) models harboring human tumors. These types of models have been used to study cancer initiation and progression as well as preclinical evaluation of anticancer drugs. One major limiting factor for both these model systems is the immune system; the PDX models lack an immune system and the immune system in immunocompetent mouse models display differences compared to the human immune system. Thus, in cancer research there is a need for preclinical models to study the influence of human immune cells on tumor progression and response to cancer therapies. We have established and optimized protocols for intravenous (IV) or intraperitoneal (IP) injections of isolated human PBMCs, to generate humanized mice harboring human immune cells. Our protocols do not require irradiation or busulfan pretreatment of the animals. Flow cytometry analyses showed that mainly T helper cells, CD4+, and cytotoxic T cells, CD8+, were present in the humanized mice. Immunohistochemistry (IHC) analyses of humanized PDX cancer model mice showed that human lymphocytes were present in the tumor periphery and some very few cells within the tumor, in addition to the human leukocytes in the liver and spleen. The growth rates of the PDX tumors were not affected by the humanization. Our protocols require minimal preparations of the animals and generate humanized PDX mice harboring human lymphocytes locating in close proximity of, as well as inside the PDX tumors. The model systems are suitable for preclinical studies of human, adaptive immune responses in tumor progression and cancer therapies.

Citation Format: Jens Henrik Norum, Dag Josefsen, Gunnar Kvalheim, Olav Engebråten, Therese Sørlie, Gunhild M. Mælandsmo. Humanization of patient derived xenograft (PDX) cancer model mice with peripheral blood mononuclear cells (PBMCs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1660. doi:10.1158/1538-7445.AM2017-1660

Abstract 4412: Metabolic reprogramming in EMT - targeting regulatory nodes in mesenchymal cells

To combat cancer we have to avoid development of resistant and metastatic disease. Breast cancer cells can switch from an epithelial to mesenchymal phenotype through a process called epithelial to mesenchymal transition/EMT. Emerging evidence suggests that this process is vital to avoid treatment pressure and to gain metastatic capacity. Furthermore, recent literature shows that metabolic reprogramming is an essential attribute of cellular plasticity. Metabolic targeting could therefore be an attractive possibility to prevent development of resistance and metastatic dissemination. Here we tried to understand the metabolic phenotype of EMT and the mechanisms linking the metabolic programs to cellular plasticity. We also aimed to unravel compensatory metabolic pathways and use the metabolic inhibitors to sensitize breast cancer cells to conventional therapy.

To that end we have investigated the metabolic signature of the D492 EMT cell model. The D492 cell line, established from human breast epithelial progenitor cells, has retained stem cell characteristics and has the ability to undergo EMT upon stromal (endothelial) influence, forming the mesenchymal D492M cells. Thus, D492 cell system has preserved the natural flexibility of breast epithelial progenitor cells, and constitutes a unique platform to unravel the factors responsible for stromal cell-induced cellular plasticity.

We show that metabolic reprogramming is essential for induction of the mesenchymal phenotype using metabolomic profiling. Using Ultra performance liquid chromatography Mass Spectrometry and gene expression profiling we have created genome-scale metabolic models of D492 and D492M. Our data show that glycolytic flux and oxidative phosphorylation is higher in D492, however, D492M cells rely more on amino acid anaplerosis and fatty acid oxidation to fuel the TCA cycle. Glutamine and glucose tracing using NMR will give further insight into the difference in metabolism between the two cell lines.

We have used these data to find metabolic targets that lock the cells in the epithelial state or identify the means to induce lethality in the mesenchymal cells.

Using the metabolic rewiring of EMT in the D492 cell model we can understand the mechanisms responsible for treatment resistance, identify compensatory metabolic pathways during treatment and find metabolic inhibitors that will sensitize BC cells to conventional therapy.

Citation Format: Bylgja Hilmarsdottir, Skarphedinn Halldorsson, Maria T. Grinde, Anna Barkovskaya, Solveig Pettersen, Thorarinn Gudjonsson, Siver A. Moestue, Ottar Rolfsson, Gunhild M. Mælandsmo. Metabolic reprogramming in EMT - targeting regulatory nodes in mesenchymal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4412. doi:10.1158/1538-7445.AM2017-4412

The MetAction project: Biomarker-directed molecularly matched therapy for end-stage cancer implemented in clinical practice

e14033

Background: The MetAction project consists of two clinical trial phases. The completed first phase established the required diagnostic infrastructure, implemented security-approved systems for handling of sensitive information, educated the entire project staff within the context of tumor boards, and estimated costs of the initiative within public health services. The endeavor enabled expedite and safe mutation profiling of metastatic tumors in order to offer biomarker-based treatment with molecularly matched medication to patients with end-stage cancer, as reported in Ree et al., ESMO Open 2017. The ongoing second trial phase investigates the feasibility of the established MetAction pipeline in clinical practice. Methods: An eligible patient has end-stage metastatic disease from a solid cancer. Metastatic tissue is analyzed by DNA sequencing (Ion Oncomine™ Comprehensive Panel), where called variants are filtered prior to assessment and prioritization, supplemented with fluorescence in situ hybridization to cover relevant biomarkers. The Molecular Tumor Board interprets the findings within the likelihood of signaling pathway activity, and the sequential Clinical Tumor Board (CTB) may conclude on treatment with any systemic tumor-directed medication. Results: At the time of writing, 19 patients enrolled onto the second trial phase have accomplished the diagnostic procedures from sampling of metastatic tissue to CTB conclusion. Biopsy procedures were undertaken at lung or pleural sites (five cases), liver or superficial or deep peritoneal sites (13 cases), and an inguinal lymph node (one case) and did not cause adverse events. Histologic entities were 12 adenocarcinomas and one case each of squamous cell and undifferentiated carcinoma, cholangiocarcinoma, and four different sarcoma entities. Twelve patients have been found eligible for off-label use of molecularly matched therapy (inhibitor of ALK-, BRAF-, EGFR-, FGFR-, mTOR-, PARP-, or PD-1-mediated signaling). Conclusions: We will report on patient outcome (progression-free survival, overall response rate, and tolerance) to this biomarker-directed treatment in end-stage cancer. Clinical trial information: NCT02142036.

Inhibition of PTP1B disrupts cell-cell adhesion and induces anoikis in breast epithelial cells

Protein tyrosine phosphatase 1B (PTP1B) is a well-known inhibitor of insulin signaling pathways and inhibitors against PTP1B are being developed as promising drug candidates for treatment of obesity. PTP1B has also been linked to breast cancer both as a tumor suppressor and as an oncogene. Furthermore, PTP1B has been shown to be a regulator of cell adhesion and migration in normal and cancer cells. In this study, we analyzed the PTP1B expression in normal breast tissue, primary breast cells and the breast epithelial cell line D492. In normal breast tissue and primary breast cells, PTP1B is widely expressed in both epithelial and stromal cells, with highest expression in myoepithelial cells and fibroblasts. PTP1B is widely expressed in branching structures generated by D492 when cultured in 3D reconstituted basement membrane (3D rBM). Inhibition of PTP1B in D492 and another mammary epithelial cell line HMLE resulted in reduced cell proliferation and induction of anoikis. These changes were seen when cells were cultured both in monolayer and in 3D rBM. PTP1B inhibition affected cell attachment, expression of cell adhesion proteins and actin polymerization. Moreover, epithelial to mesenchymal transition (EMT) sensitized cells to PTP1B inhibition. A mesenchymal sublines of D492 and HMLE (D492M and HMLEmes) were more sensitive to PTP1B inhibition than D492 and HMLE. Reversion of D492M to an epithelial state using miR-200c-141 restored resistance to detachment induced by PTP1B inhibition. In conclusion, we have shown that PTP1B is widely expressed in the human breast gland with highest expression in myoepithelial cells and fibroblasts. Inhibition of PTP1B in D492 and HMLE affects cell–cell adhesion and induces anoikis-like effects. Finally, cells with an EMT phenotype are more sensitive to PTP1B inhibitors making PTP1B a potential candidate for further studies as a target for drug development in cancer involving the EMT phenotype.

Implementing precision cancer medicine in the public health services of Norway: the diagnostic infrastructure and a cost estimate

OBJECTIVE

Through the conduct of an individual-based intervention study, the main purpose of this project was to build and evaluate the required infrastructure that may enable routine practice of precision cancer medicine in the public health services of Norway, including modelling of costs.

METHODS

An eligible patient had end-stage metastatic disease from a solid tumour. Metastatic tissue was analysed by DNA sequencing, using a 50-gene panel and a study-generated pipeline for analysis of sequence data, supplemented with fluorescence in situ hybridisation to cover relevant biomarkers. Cost estimations compared best supportive care, biomarker-agnostic treatment with a molecularly targeted agent and biomarker-based treatment with such a drug. These included costs for medication, outpatient clinic visits, admission from adverse events and the biomarker-based procedures.

RESULTS

The diagnostic procedures, which comprised sampling of metastatic tissue, mutation analysis and data interpretation at the Molecular Tumor Board before integration with clinical data at the Clinical Tumor Board, were completed in median 18 (8-39) days for the 22 study patients. The 23 invasive procedures (12 from liver, 6 from lung, 5 from other sites) caused a single adverse event (pneumothorax). Per patient, 0-5 mutations were detected in metastatic tumours; however, no actionable target case was identified for the current single-agent therapy approach. Based on the cost modelling, the biomarker-based approach was 2.5-fold more costly than best supportive care and 2.5-fold less costly than the biomarker-agnostic option.

CONCLUSIONS

The first project phase established a comprehensive diagnostic infrastructure for precision cancer medicine, which enabled expedite and safe mutation profiling of metastatic tumours and data interpretation at multidisciplinary tumour boards for patients with end-stage cancer. Furthermore, it prepared for protocol amendments, recently approved by the designated authorities for the second study phase, allowing more comprehensive mutation analysis and opportunities to define therapy targets.

Integrative clustering reveals a novel split in the luminal A subtype of breast cancer with impact on outcome

BACKGROUND

Breast cancer is a heterogeneous disease at the clinical and molecular level. In this study we integrate classifications extracted from five different molecular levels in order to identify integrated subtypes.

METHODS

Tumor tissue from 425 patients with primary breast cancer from the Oslo2 study was cut and blended, and divided into fractions for DNA, RNA and protein isolation and metabolomics, allowing the acquisition of representative and comparable molecular data. Patients were stratified into groups based on their tumor characteristics from five different molecular levels, using various clustering methods. Finally, all previously identified and newly determined subgroups were combined in a multilevel classification using a "cluster-of-clusters" approach with consensus clustering.

RESULTS

Based on DNA copy number data, tumors were categorized into three groups according to the complex arm aberration index. mRNA expression profiles divided tumors into five molecular subgroups according to PAM50 subtyping, and clustering based on microRNA expression revealed four subgroups. Reverse-phase protein array data divided tumors into five subgroups. Hierarchical clustering of tumor metabolic profiles revealed three clusters. Combining DNA copy number and mRNA expression classified tumors into seven clusters based on pathway activity levels, and tumors were classified into ten subtypes using integrative clustering. The final consensus clustering that incorporated all aforementioned subtypes revealed six major groups. Five corresponded well with the mRNA subtypes, while a sixth group resulted from a split of the luminal A subtype; these tumors belonged to distinct microRNA clusters. Gain-of-function studies using MCF-7 cells showed that microRNAs differentially expressed between the luminal A clusters were important for cancer cell survival. These microRNAs were used to validate the split in luminal A tumors in four independent breast cancer cohorts. In two cohorts the microRNAs divided tumors into subgroups with significantly different outcomes, and in another a trend was observed.

CONCLUSIONS

The six integrated subtypes identified confirm the heterogeneity of breast cancer and show that finer subdivisions of subtypes are evident. Increasing knowledge of the heterogeneity of the luminal A subtype may add pivotal information to guide therapeutic choices, evidently bringing us closer to improved treatment for this largest subgroup of breast cancer.

Abstract P6-13-01: Proteomic response in breast cancer treated with neoadjuvant chemotherapy with and without bevacizumab: Reverse phase protein array (RPPA) results from NeoAva - A randomized phase II study

BACKGROUND: Patients with HER2 negative primary tumors of ≥25 mm were treated with neoadjuvant chemotherapy (4 x FEC100 + 12 weeks of taxane-based therapy) and randomized (1:1) to receive bevacizumab or not. Mammography, ultrasound and MR imaging were used for response evaluation, in addition to the final pathology assessment after surgery.

HYPOTHESIS: RPPA proteomic analyses support identification of molecular mechanisms associated with clinical response to bevacizumab treatment.

METHODS: Tumor responses were evaluable in 132 patients; of which 66 received bevacizumab. Ratio of the tumor size at final pathology assessment, and at inclusion was calculated to obtain a continuous scale of response reflecting the percentage of tumor shrinkage in response to therapy. Tumor material was obtained at screening, 12 weeks into treatment and at surgical removal of tumors at 25 weeks. Lysates from each sample was analyzed on reverse phase protein arrays (RPPA) for expression levels of 210 proteins of which 54 were phospho-specific.

RESULTS: Several proteins were found for which expression prior to treatment reflected a better response on tumor shrinkage in the combination treatment arm (chemotherapy+bevacizumab). The proteomic response from week 0 to 12 in both treatment arms had an overall similar profile regarding up- and down-regulated proteins; however, the combination treatment (FEC100 + bevacizumab) induced a more pronounced effect on regulation of each protein. This might reflect the capability of bevacizumab therapy to potentiate the effects of the anthracyclin based chemotherapy from week 0 to 12. Conversely, from week 12-25 (taxane-based therapy + bevacizumab) this effect was lost or even reversed, except for certain phosphoproteins where potentiation imposed by bevacizumab was sustained throughout the whole treatment period. We are in the process of analyzing the impact of phosphorylation and thus protein activation states on treatment response. Furthermore, tumors with low hormone receptor pathway score demonstrated a better response in the combination treatment (chemotherapy+bevacizumab). Additionally, in these good responders the hormone signaling pathway was significantly upregulated during treatment. Further investigations are conducted to determine if this was due to selective ablation of hormone receptor negative tumor cells, or a re-programming of the molecular phenotype of cells present prior to treatment. The above mentioned results have potentially important clinical relevance and will be further investigated with respect to subtypes and the biological pathways affected by antiangiogenic therapy.

Citation Format: Haugen MH, Lindgjærde OC, Krohn M, Zhao W, Lindholm EM, Silwal-Pandit L, Borgen E, Garred Ø, Fangberget A, Holmen MM, Schlichting E, Skjerven H, Lundgren S, Wist E, Naume B, Mælandsmo GM, Lu Y, Børresen-Dale A-L, Mills GB, Engebråten O. Proteomic response in breast cancer treated with neoadjuvant chemotherapy with and without bevacizumab: Reverse phase protein array (RPPA) results from NeoAva - A randomized phase II study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-13-01.

Prognostic significance of S100A4-expression and subcellular localization in early-stage breast cancer

PURPOSE

Prognostic factors are useful in order to identify early-stage breast cancer patients who might benefit from adjuvant treatment. The metastasis-promoting protein S100A4 has previously been associated with poor prognosis in breast cancer patients. The protein is expressed in diverse subcellular compartments, including the cytoplasm, extracellular space, and nucleus. Nuclear expression is an independent predictor of poor outcome in several cancer types, but the significance of subcellular expression has not yet been assessed in breast cancer.

METHODS

Nuclear and cytoplasmic expression of S100A4 was assessed by immunohistochemistry in prospectively collected tumor samples from early-stage breast cancer patients using tissue microarrays.

RESULTS

In patients not receiving adjuvant systemic therapy, nuclear or cytoplasmic expression was found in 44/291 tumors (15%). Expression of either nuclear or cytoplasmic S100A4 was associated with histological grade III, triple-negative subtype, and Ki-67-expression. Patients with S100A4-positive tumors had inferior metastasis-free and overall survival compared to S100A4-negative. When expression was analyzed separately, nuclear S100A4 was a significant predictor of outcome, while cytoplasmic was not. In patients who received adjuvant treatment 23/300 tumors (8%) were S100A4-positive, but no tumors displayed nuclear staining alone. S100A4-expression was strongly associated with histological grade III and triple-negative subtype. Although not significant, metastasis-free and overall survival was numerically reduced in patients with S100A4-positive tumors.

CONCLUSION

S100A4-expression was associated with poor outcome in early-stage breast cancer, but the low percentage of positive tumors and the modest survival differences imply that the clinical utility in selection of patients for adjuvant treatment is limited.

hvTRA, a novel TRAIL receptor agonist, induces apoptosis and sustained growth retardation in melanoma

In recent years, new treatment options for malignant melanoma patients have enhanced the overall survival for selected patients. Despite new hope, most melanoma patients still relapse with drug-resistant tumors or experience intrinsic resistance to the therapy. Therefore, novel treatment modalities beneficial for subgroups of patients are needed. TRAIL receptor agonists have been suggested as promising candidates for use in cancer treatment as they preferentially induce apoptosis in cancer cells. Unfortunately, the first generation of TRAIL receptor agonists showed poor clinical efficacy. hvTRA is a second-generation TRAIL receptor agonist with improved composition giving increased potency, and in the present study, we showed hvTRA-induced activation of apoptosis leading to an efficient and sustained reduction in melanoma cell growth in cell lines and xenograft models. Furthermore, the potential of hvTRA in a clinical setting was demonstrated by showing efficacy on tumor cells harvested from melanoma patients with lymph node metastasis in an ex vivo drug sensitivity assay. Inhibition of mutated BRAF has been shown to regulate proteins in the intrinsic apoptotic pathway, making the cells more susceptible for apoptosis induction. In an attempt to increase the efficacy of hvTRA, combination treatment with the mutated BRAF inhibitor vemurafenib was investigated. A synergistic effect by the combination was observed for several cell lines in vitro, and an initial cytotoxic effect was observed in vivo. Unfortunately, the initial increased reduction in tumor growth compared with hvTRA mono treatment was not sustained, and this was related to downregulation of the DR5 level by vemurafenib. Altogether, the presented data imply that hvTRA efficiently induce apoptosis and growth delay in melanoma models and patient material, and the potential of this TRAIL receptor agonist should be further evaluated for treatment of subgroups of melanoma patients.

Use of non-invasive imaging to monitor response to aflibercept treatment in murine models of colorectal cancer liver metastases

The liver is the most frequent metastatic site in colorectal cancer (CRC), and relevant orthotopic in vivo models are needed to study the efficacy of anticancer drugs in the metastatic setting. A challenge when utilizing such models is monitoring tumor growth during the experiments. In this study, experimental liver metastases were established in nude mice by splenic injection of the CRC cell lines HT29 and HCT116, and the mice were treated with the antiangiogenic drug aflibercept. Tumor growth was monitored using magnetic resonance imaging (MRI) and bioluminescence imaging (BLI). Aflibercept treatment was well tolerated and resulted in increased animal survival in HCT116, but not in HT29, while inhibited tumor growth was observed in both models. Treatment efficacy was monitored with high precision using MRI, while BLI detected small-volume disease with high sensitivity, but was less accurate in end-stage disease. Apparent diffusion coefficient (ADC) values obtained by diffusion weighted MRI (DW-MRI) were highly predictive of treatment response, with increased ADC corresponding well with areas of necrosis observed by histological evaluation of aflibercept-treated xenografts. The results showed that the efficacy of the antiangiogenic drug aflibercept varied between the two models, possibly reflecting unique growth patterns in the liver that may be representative of human disease. Non-invasive imaging, especially MRI and DW-MRI, can be used to effectively monitor tumor growth and treatment response in orthotopic liver metastasis models.

Evaluation of CD146 as Target for Radioimmunotherapy against Osteosarcoma

BACKGROUND

Osteosarcoma is a rare form of cancer but with a substantial need for new active drugs. There is a particular need for targeted therapies to combat metastatic disease. One possible approach is to use an antibody drug conjugate or an antibody radionuclide conjugate to target the osteosarcoma metastases and circulating tumor cells. Herein we have evaluated a radiolabeled monoclonal antibody targeting CD146 both in vitro and in vivo.

METHODS AND RESULTS

A murine monoclonal anti-CD146 IgG1 isotype antibody, named OI-3, was developed along with recombinant chimeric versions with human IgG1 or human IgG3 Fc sequences. Using flow cytometry, selective binding of OI-3 to human osteosarcoma cell lines OHS, KPDX and Saos-2 was confirmed. The results confirm a higher expression level of CD146 on human osteosarcoma cells than HER2 and EGFR; antigens targeted by commercially available therapeutic antibodies. The biodistribution of 125I-labeled OI-3 antibody variants was compared with 125I-labeled chimeric anti-EGFR antibody cetuximab in nude mice with subcutaneous OHS osteosarcoma xenografts. OI-3 was able to target CD146 expressing tumors in vivo and showed improved tumor to tissue targeting ratios compared with cetuximab. Subsequently, the three OI-3 variants were conjugated with p-SCN-Bn-DOTA and labeled with a more therapeutically relevant radionuclide, 177Lu, and their biodistributions were studied in the nude mouse model. The 177Lu-labeled OI-3 variants were stable and had therapeutically relevant biodistribution profiles. Dosimetry estimates showed higher absorbed radiation dose to tumor than all other tissues after administration of the chimeric IgG1 OI-3 variant.

CONCLUSION

Our results indicate that CD146 can be targeted in vivo by the radiolabeled OI-3 antibodies.

STAMP2 is required for human adipose-derived stem cell differentiation and adipocyte-facilitated prostate cancer growth in vivo

Six Transmembrane Protein of Prostate 2 (STAMP2) has been implicated in both prostate cancer (PCa) and metabolic disease. STAMP2 has unique anti-inflammatory and pro-metabolic properties in mouse adipose tissue, but there is limited information on its role in human metabolic tissues. Using human adipose-derived stem cells (ASCs), we report that STAMP2 expression is dramatically upregulated during adipogenesis. shRNA-mediated STAMP2 knockdown in ASCs significantly suppresses adipogenesis and interferes with optimal expression of adipogenic genes and adipocyte metabolic function. Furthermore, ASC-derived adipocyte-mediated stimulation of prostate tumor growth in nude mice is significantly reduced upon STAMP2 knockdown in ASC adipocytes. These results suggest that STAMP2 is crucial for normal ASC conversion into adipocytes and their metabolic function, as well as their ability to facilitate PCa growth in vivo.

Abstract 4218: Diffusion-weighted MRI can predict response to aflibercept in in vivo models

BACKGROUND: The liver is the most frequent metastatic site in colorectal cancer (CRC), and relevant in vivo models are needed to study the efficacy of anticancer drugs in this setting. Aflibercept, targeting vascular endothelial growth factors A and B and placental growth factor, is one of the most recently approved antiangiogenic agents for treatment of metastatic CRC. In the present work, the efficacy of aflibercept was investigated in experimental models of liver metastases in nude mice and growth progression was monitored using non-invasive imaging.

METHODS: Liver metastases were established in mice by intrasplenic injection of CRC cell lines HCT116 and HT29 transfected with luciferase. Magnetic resonance imaging (MRI) (7T) and bioluminescent imaging (IVIS spectrum) were used to monitor tumor growth. Aflibercept was delivered intraperitoneally. To further characterize treatment response in metastatic tumors, diffusion-weighted (DW)-MR images were obtained. At termination tumors were sampled for histopathologic analysis.

RESULTS: Mice bearing HCT116 xenografts responded well to treatment and a significant increase in survival compared to vehicle treated animals was observed (p&lt; 0.001), in addition to decreased tumor burden. No increase in survival was observed upon aflibercept treatment in HT29 xenografts (p = 0.155), whereas in one of two experiments performed a significant reduction in tumor volume was observed, suggesting that there was a slight response to treatment.

T2-weighted MRI was used to quantify tumor volume by manual delineation using the OsiriX software. MRI-assessed tumor volumes correlated well with tumor weight at the time of termination, while for bioluminescence measurements no such correlation was observed. In contrast, bioluminescence was a sensitive detection method early in the experiments when MRI did not show liver tumor.

DW-MRI was obtained and apparent diffusion coefficient (ADC) tumor maps were calculated using the nordicIce software. A slight increase in ADC values was observed for HT29 tumors while there was a large increase in ADC values for HCT116 tumors after treatment with aflibercept. This corresponded well with histologic evaluation of tumors, showing increased necrosis in HCT116 tumors, but not in HT29 tumors.

CONCLUSION: Our results demonstrate efficacy of aflibercept in an orthotopic model of liver metastases in CRC. MRI could be used to monitor treatment efficacy with high precision, while bioluminescence measurement could detect small-volume disease with high sensitivity, but was less specific in high-volume disease. Interestingly, ADC values obtained from DW-MRI were highly predictive of treatment response by clearly visualizing and quantifying tumor necrosis.

Citation Format: Karianne G. Fleten, Kine M. Bakke, Andreas Abildgaard, Gunhild M. Mælandsmo, Katrine Røe Redalen, Kjersti Flatmark. Diffusion-weighted MRI can predict response to aflibercept in in vivo models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4218.

Abstract 3737: Inhibition of O-GlcNAc transferase in tamoxifen resistant breast cancer cells

O-linked N-acetyl-glucosamine transferase (OGT) is an enzyme that catalyzes addition of the O-GlcNAc modification to a wide range of intracellular proteins. The O-GlcNAc modification is a product of the hexosamine biosynthetic pathway, which requires glucose and glutamine as substrates. Uptake of both of these nutrients is often up-regulated in cancer, which in turn leads to an increase in the total protein O-GlcNAcylation. Increased OGT expression has also been reported in most cancer types, including the most frequently diagnosed cancer in women, breast cancer. Many of the breast cancers rely on estrogen receptor alpha (ERα) for proliferation and have shown a strong response to the ERα inhibition, most commonly achieved by treatment with tamoxifen. However, while efficient, prolonged exposure to tamoxifen commonly causes resistance and relapse of the disease. It is therefore vital to uncover mechanisms which contribute to the resistance in order to develop adequate treatment strategy for these patients.

Here, we have investigated the effect of targeting OGT in an isogenic pair of ERα-positive tamoxifen-sensitive MCF7 and tamoxifen-resistant TAMR breast cancer cell lines. OGT inhibition decreased viability and triggered cell death in both cell lines. These responses were associated with over 50% reduction in ERα expression in both MCF7 and TAMR cells. Reduced O-GlcNAcylation has previously been reported to induce endoplasmic reticulum stress and activation of transcription factor C/EBP homologous protein (CHOP), which promotes cell death. Targeting OGT resulted in a strong increase of CHOP expression, which appeared more prominent in the TAMR cells. Finally, targeting OGT induced a very pronounced cell cycle arrest in the G2/M phase in the TAMR cells, while the MCF7 cell lined showed a very modest response.

Taken together, these results indicate that targeting OGT leads to a differential response in the tamoxifen-sensitive and resistant breast cancer cells. Currently, we are using an expanded panel of tamoxifen-resistant cell lines to perform expression microarrays, metabolic flux assays and DNA damage response analysis in order to uncover the cause of the differential response to OGT targeting. This may help us identify potential therapeutic combinations that might be suitable for treatment of tamoxifen-resistant cancers.

Citation Format: Anna Barkovskaya, Lina Prasmickaite, Ian G. Mills, Gunhild M. Mælandsmo, Siver A. Moestue, Harri M. Itkonen. Inhibition of O-GlcNAc transferase in tamoxifen resistant breast cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3737.

Expression and clinical significance of Wee1 in colorectal cancer

Wee1 is a nuclear kinase regulating cell cycle progression, and has emerged as a promising therapeutic target in cancer. Expression of Wee1 has been associated with poor outcome in certain tumor types, but the prognostic impact and clinical significance in colorectal cancer is unknown. The expression of Wee1 was examined by immunohistochemistry in primary colorectal carcinomas from a prospectively collected patient cohort, and associations with clinicopathological parameters and outcome were investigated. Cell culture experiments were performed using the cell lines RKO and SW620, and the relationship with the metastasis-promoting protein S100A4 was investigated. Nuclear expression was detected in 229 of the 258 tumors analyzed (89 %). Wee1 staining was associated with low pT stage, but no other significant associations with demographic or histopathological variables were found. Moderate Wee1 staining intensity was a predictor of favorable metastasis-free and overall survival compared to strong intensity and no or weak staining. The fraction of positive cells was not a prognostic factor in the present cohort. Inhibition of Wee1 expression using siRNA or treatment with the Wee1 inhibitor MK-1775 reduced expression of the metastasis-promoting protein S100A4, but no relationship between Wee1 and S100A4 was found in the patient samples. In conclusion, Wee1 is highly expressed in primary colorectal carcinomas, but few relevant associations with clinicopathological parameters or outcome were found. The lack of clinical significance of Wee1 expression could indicate that other tumor types might be better suited for further development of Wee1 inhibitors.

Fibroblast-induced switching to the mesenchymal-like phenotype and PI3K/mTOR signaling protects melanoma cells from BRAF inhibitors

The knowledge on how tumor-associated stroma influences efficacy of anti-cancer therapy just started to emerge. Here we show that lung fibroblasts reduce melanoma sensitivity to the BRAF inhibitor (BRAFi) vemurafenib only if the two cell types are in close proximity. In the presence of fibroblasts, the adjacent melanoma cells acquire de-differentiated mesenchymal-like phenotype. Upon treatment with BRAFi, such melanoma cells maintain high levels of phospho ribosomal protein S6 (pS6), i.e. active mTOR signaling, which is suppressed in the BRAFi sensitive cells without stromal contacts. Inhibitors of PI3K/mTOR in combination with BRAFi eradicate pS6high cell subpopulations and potentiate anti-cancer effects in melanoma protected by the fibroblasts. mTOR and BRAF co-inhibition also delayed the development of early-stage lung metastases in vivo. In conclusion, we demonstrate that upon influence from fibroblasts, melanoma cells undergo a phenotype switch to the mesenchymal state, which can support PI3K/mTOR signaling. The lost sensitivity to BRAFi in such cells can be overcome by co-targeting PI3K/mTOR. This knowledge could be explored for designing BRAFi combination therapies aiming to eliminate both stroma-protected and non-protected counterparts of metastases.

Abstract A36: Protein expression analysis of intratumor heterogeneity in a luminal-like breast cancer xenograft

Estrogen receptor is a key driver in breast cancer and is expressed in about 75% of breast tumors. ER positive tumors are susceptible to endocrine therapies; however, the major obstacle for curative treatment is recurrence due to resistance to anti-estrogens. Endocrine therapies may induce a selective pressure promoting growth of estrogen independent cell subclones. Our aim was to reveal molecular changes occurring in tumors in response to anti-estrogen treatment, and to identify subpopulations of cells able to withstand anti-estrogen treatment.

A luminal-like estrogen-dependent orthotopically growing xenograft model was treated with fulvestrant, or exposed to estrogen deprivation. The effect of ER-signaling inhibition was analyzed using quantitative mass spectrometry (MS) -based proteomic analysis and high resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS). Cell surface marker expression (CD24 and SSEA-4) was monitored by flow cytometry, allowing detailed comparison of protein expression between intratumor cell subpopulations.

We found that both modes of anti-estrogen therapy restrained tumor growth and induced expression of enzymes involved in TCA cycle, oxidative phosphorylation and fatty acid beta-oxidation. This was accompanied by changes in levels of specific metabolites indicative of a possible reprogramming of cell metabolism and utilization of oxidative phosphorylation in preference to aerobic glycolysis (decrease in Warburg effect). Furthermore, anti-estrogen treatment seemed to have selective effects on intratumor cell subpopulations, specified by expression of the markers CD24 and SSEA-4. More specifically, highly tumorigenic CD24low/SSEA-4low (dbl. low) cells were eliminated and the seemingly more benign CD24high/SSEA-4high (dbl. high) cells were enriched in the residual tumor. When comparing the proteome in dbl. low verus dbl. high cells sorted from untreated tumors, metabolism was one of the most differentially enriched processes. Enzymes involved in glycolysis, TCA cycle, respiratory electron transport chain and fatty acid were more abundant in the dbl. high subpopulation.

These results suggest that cancer cells may reprogram their metabolism in response to anti-estrogen therapy to support a less estrogen-dependent phenotype. Moreover, subpopulations of cells with different metabolism may exist within the growing tumor, and these may respond differently to anti-estrogen treatment.

Citation Format: Nirma Skrbo, Ufuk Kirik, Alexandr Kristian, Paolo Cifani, Linn Antberg, Siver A. Moestue, Olav Engebraaten, Gunhild M. Mælandsmo, Kristin Andersen, Peter James, Therese Sørlie. Protein expression analysis of intratumor heterogeneity in a luminal-like breast cancer xenograft. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr A36.

Zebrafish as a model system for characterization of nanoparticles against cancer

Therapeutic nanoparticles (NPs) have great potential to deliver drugs against human diseases. Encapsulation of drugs in NPs protects them from being metabolized, while they are delivered specifically to a target site, thereby reducing toxicity and other side-effects. However, non-specific tissue accumulation of NPs, for example in macrophages, especially in the spleen and liver is a general problem with many NPs being developed for cancer therapy. To address the problem of non-specific tissue accumulation of NPs we describe the development of the zebrafish embryo as a transparent vertebrate system for characterization of NPs against cancer. We show that injection of human cancer cells results in tumor-like structures, and that subsequently injected fluorescent NPs, either made of polystyrene or liposomes can be imaged in real-time. NP biodistribution and general in vivo properties can be easily monitored in embryos having selective fluorescent labeling of specific tissues. We demonstrate in vitro, by using optical tweezer micromanipulation, microscopy and flow cytometry that polyethylene glycol (PEG) coating of NPs decreases the level of adhesion of NPs to macrophages, and also to cancer cells. In vivo in zebrafish embryos, PEG coating resulted in longer NP circulation times, decreased macrophage uptake, and reduced adhesion to the endothelium. Importantly, liposomes were observed to accumulate passively and selectively in tumor-like structures comprised of human cancer cells. These results show that zebrafish embryo is a powerful system for microscopy-based screening of NPs on the route to preclinical testing.

STAMP2 increases oxidative stress and is critical for prostate cancer

The six transmembrane protein of prostate 2 (STAMP2) is an androgen-regulated gene whose mRNA expression is increased in prostate cancer (PCa). Here, we show that STAMP2 protein expression is increased in human PCa compared with benign prostate that is also correlated with tumor grade and treatment response. We also show that STAMP2 significantly increased reactive oxygen species (ROS) in PCa cells through its iron reductase activity which also depleted NADPH levels. Knockdown of STAMP2 expression in PCa cells inhibited proliferation, colony formation, and anchorage-independent growth, and significantly increased apoptosis. Furthermore, STAMP2 effects were, at least in part, mediated by activating transcription factor 4 (ATF4), whose expression is regulated by ROS. Consistent with in vitro findings, silencing STAMP2 significantly inhibited PCa xenograft growth in mice. Finally, therapeutic silencing of STAMP2 by systemically administered nanoliposomal siRNA profoundly inhibited tumor growth in two established preclinical PCa models in mice. These data suggest that STAMP2 is required for PCa progression and thus may serve as a novel therapeutic target.

Enrichment of nuclear S100A4 during G2/M in colorectal cancer cells: possible association with cyclin B1 and centrosomes

S100A4 promotes metastasis in several types of cancer, but the involved molecular mechanisms are still incompletely described. The protein is associated with a wide variety of biological functions and it locates to different subcellular compartments, including nuclei, cytoplasm and extracellular space. Nuclear expression of S100A4 has been associated with more advanced disease stage as well as poor outcome in colorectal cancer (CRC). The present study was initiated to investigate the nuclear function of S100A4 and thereby unravel potential biological mechanisms linking nuclear expression to a more aggressive phenotype. CRC cell lines show heterogeneity in nuclear S100A4 expression and preliminary experiments revealed cells in G2/M to have increased nuclear accumulation compared to G1 and S cells, respectively. Synchronization experiments validated nuclear S100A4 expression to be most prominent in the G2/M phase, but manipulating nuclear levels of S100A4 using lentiviral modified cells failed to induce changes in cell cycle distribution and proliferation. Proximity ligation assay did, however, demonstrate proximity between S100A4 and cyclin B1 in vitro, while confocal microscopy showed S100A4 to localize to areas corresponding to centrosomes in mitotic cells prior to chromosome segregation. This might indicate a novel and uncharacterized function of the metastasis-associated protein in CRC cells.

Metabolic reprogramming supports the invasive phenotype in malignant melanoma

Invasiveness is a hallmark of aggressive cancer like malignant melanoma, and factors involved in acquisition or maintenance of an invasive phenotype are attractive targets for therapy. We investigated melanoma phenotype modulation induced by the metastasis-promoting microenvironmental protein S100A4, focusing on the relationship between enhanced cellular motility, dedifferentiation and metabolic changes. In poorly motile, well-differentiated Melmet 5 cells, S100A4 stimulated migration, invasion and simultaneously down-regulated differentiation genes and modulated expression of metabolism genes. Metabolic studies confirmed suppressed mitochondrial respiration and activated glycolytic flux in the S100A4 stimulated cells, indicating a metabolic switch toward aerobic glycolysis, known as the Warburg effect. Reversal of the glycolytic switch by dichloracetate induced apoptosis and reduced cell growth, particularly in the S100A4 stimulated cells. This implies that cells with stimulated invasiveness get survival benefit from the glycolytic switch and, therefore, become more vulnerable to glycolysis inhibition. In conclusion, our data indicate that transition to the invasive phenotype in melanoma involves dedifferentiation and metabolic reprogramming from mitochondrial oxidation to glycolysis, which facilitates survival of the invasive cancer cells. Therapeutic strategies targeting the metabolic reprogramming may therefore be effective against the invasive phenotype.

Evaluation of serum osteopontin level and gene polymorphism as biomarkers: analyses from the Nordic Adjuvant Interferon alpha Melanoma trial

Malignant melanoma is highly aggressive cancer with poor prognosis and few therapeutic options. Interferon alpha (IFN-α) has been tested as adjuvant immunotherapy in high-risk melanoma patients in a number of studies, but its beneficial role is controversial. Although IFN-α treatment can prolong relapse-free survival, the effect on overall survival is not significant. However, a small subset of patients benefits from the treatment, signifying the need for biomarkers able to identify a responding subgroup. Here we evaluated whether serum osteopontin (OPN) could function as a biomarker identifying patients with poor prognosis that might benefit from IFN-α. The choice of osteopontin was based on the knowledge about the dual role of this protein in cancer and immune response, an apparent association between OPN and IFN signaling and a prognostic value of OPN in multiple other tumor types. Serum samples from 275 high-risk melanoma patients enrolled in the Nordic Adjuvant IFN Melanoma trial were analyzed for circulating OPN concentrations and OPN promoter polymorphisms in position -443. The potential relation between serum OPN levels, the genotypes and survival in non-treated patients and patients receiving adjuvant IFN-α was investigated. Although slightly better survival was observed in the treated patients that had high levels of OPN, the difference was not statistically significant. In conclusion, serum OPN (its level or the genotype) cannot distinguish melanoma patients with poor prognosis, or patients that might benefit from adjuvant treatment with IFN-α.