Ezurpimtrostat, A Palmitoyl-Protein Thioesterase-1 Inhibitor, Combined with PD-1 Inhibition Provides CD8+ Lymphocyte Repopulation in Hepatocellular Carcinoma

BACKGROUND

Palmitoyl-protein thioesterase-1 (PPT1) is a clinical stage druggable target for inhibiting autophagy in cancer.

OBJECTIVE

We aimed to determine the cellular and molecular activity of targeting PPT1 using ezurpimtrostat, in combination with an anti-PD-1 antibody.

METHODS

In this study we used a transgenic immunocompetent mouse model of hepatocellular carcinoma.

RESULTS

Herein, we revealed that inhibition of PPT1 using ezurpimtrostat decreased the liver tumor burden in a mouse model of hepatocellular carcinoma by inducing the penetration of lymphocytes into tumors when combined with anti-programmed death-1 (PD-1). Inhibition of PPT1 potentiates the effects of anti-PD-1 immunotherapy by increasing the expression of major histocompatibility complex (MHC)-I at the surface of liver cancer cells and modulates immunity through recolonization and activation of cytotoxic CD8+ lymphocytes.

CONCLUSIONS

Ezurpimtrostat turns cold tumors into hot tumors and, thus, could improve T cell-mediated immunotherapies in liver cancer.

Pancreatic cancer orthotopic graft in a murine model

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with increasing incidence. Even if progress have been made, the five-year overall survival remains lower than 10%. There is a desperate need in therapeutic improvements. In the last two decades, new in-vitro models have been developed and improved, including tridimensional-culture spheroids and organoids. However, animal studies remain mandatory in the upscaling before clinical studies. Orthotopic and syngeneic grafting is a robust model to test a drug efficiency in a tumor and its microenvironment.

METHODS

We described a method for orthotopic and syngeneic graft of KRAS mutated, p53 wildtype, 8305 cells in a C57BL/6J mouse model.

RESULTS

With this microsurgical method, 30 mice were grafted, 24 by a junior and six by a senior, resulting in 95,8 and 100% of (partial and total) successful tumoral implantation, respectively. Twenty mice underwent ultrasound follow-up. It was an efficient method for the tumoral growth evaluation. At day 16 after grafting, 85% of the tumors were detectable by ultrasound, and at day 22 all tumors were detected.

CONCLUSIONS

The presented method appears to be a robust and reliable method for pre-clinical studies. A junior master student can provide positive results using this technique, which can be improved with training.

Targeting the Tumor Microenvironment through mTOR Inhibition and Chemotherapy as Induction Therapy for Locally Advanced Head and Neck Squamous Cell Carcinoma: The CAPRA Study

Simple Summary

The PI3K-AKT-mTOR pathway is dysregulated in 70% of head and neck squamous cell carcinoma (HNSCC) and linked to the tumor microenvironment. This weekly induction treatment combined the mTOR inhibitor everolimus with carboplatin-paclitaxel chemotherapy for locally advanced T3-4/N0-3 HNSCC. In 41 patients, safety profile was favorable and overall response rate was 75.6%. Translational data demonstrated specific target engagement with p-S6K decrease in tumor tissue and pro-immunogenic cytokine release in peripheral blood. Induction treatment with chemotherapy and mTOR inhibitors may provide new therapeutic options and rationale for combinations with immune oncology agents for locally advanced HNSCC.

Abstract

Mammalian target of rapamycin (mTOR) regulates cellular functions by integrating intracellular signals and signals from the tumor microenvironment (TME). The PI3K-AKT-mTOR pathway is activated in 70% of head and neck squamous cell carcinoma (HNSCC) and associated with poor prognosis. This phase I-II study investigated the effect of mTOR inhibition using weekly everolimus (30 mg for dose level 1, 50 mg for dose level 2) combined with weekly induction chemotherapy (AUC2 carboplatin and 60 mg/m² paclitaxel) in treatment-naïve patients with locally advanced T3-4/N0-3 HNSCC. Patients received 9 weekly cycles before chemoradiotherapy. Objectives were safety and antitumor activity along with tissue and blood molecular biomarkers. A total of 50 patients were enrolled. Among 41 evaluable patients treated at the recommended dose of 50 mg everolimus weekly, tolerance was good and overall response rate was 75.6%, including 20 major responses (≥50% reduction in tumor size). A significant decrease in expression of p-S6K (p-value: 0.007) and Ki67 (p-value: 0.01) was observed in post-treatment tumor tissue. Pro-immunogenic cytokine release (Th1 cytokines IFN-γ, IL-2, and TNF-β) was observed in the peripheral blood. The combination of everolimus and chemotherapy in HNSCC was safe and achieved major tumor responses. This strategy favorably impacts the TME and might be combined with immunotherapeutic agents.

Biomarkers in Hepatobiliary Cancers: What is Useful in Clinical Practice?

Hepatocellular carcinoma (HCC) and biliary tract cancers (BTC) exhibit a poor prognosis with 5-year overall survival rates around 15%, all stages combined. Most of these primary liver malignancies are metastatic at diagnostic, with only limited therapeutic options, relying mainly on systemic therapies. Treatment modalities are different yet partially overlapping between HCC and BTC. The complex molecular profile of BTC yields to several actionable therapeutic targets, contrary to HCC that remains the field of antiangiogenic drugs in non-molecularly selected patients. Immunotherapy is now validated in the first line in HCC in combination with bevacizumab, while clinical activity of single agent immunotherapy appears limited to a subset of patients in BTC, still poorly characterized, and combinations are currently under investigation. In this review, we provide a critical evaluation and grading of clinical relevance on (i) the main prognostic biomarkers in HCC and BTC, (ii) the main theragnostic biomarkers in both tumors, and lastly (iii) what is recommended in clinical practice.

Microbiome and pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) incidence and related-deaths are increasing worldwide. PDAC is characterized by poor prognosis due to late diagnosis, high metastatic capacity and resistance to therapy. This is partially due to its specific microenvironment, where the stroma is prominent over tumor cells. Besides the oral and gut microbiota, the intratumor microbiome, i.e. the bacterial and fungal microorganisms present within the tumor, was recently introduced as a new partner of the tumor microenvironment of PDAC modulating pancreatic carcinogenesis, intratumor immune infiltrates, and response to chemotherapy. In this review, we propose an overview of current knowledge about the roles of bacteria and fungi in PDAC development and biology, and discuss potential therapeutic implications.

Abstract 5103: Bidirectional EMT-dependent modulation of cancer cell and M1/M2 macrophage differentiation

Background. Head and neck (H&N) and liver carcinomas are considered as the most deadly cancers in the world. Despite advances in diagnosis and treatment, survival rates remain low mainly due to locoregional relapse, possibly triggered by the activation of epithelial to mesenchymal transition (EMT). EMT is a critical step for tumor progression, increasing motility and invasiveness of tumor cells. M1 and M2 macrophages, major components of the tumor microenvironment, were recently described as involved in EMT. Moreover, proteins expressed by cancer cells, such as CCL2 and CSF1, and promoting M2 differentiation, have been correlated with poor prognosis, and tumor aggressiveness. The aim of this study is to understand the interactions between M1/M2 macrophages and H&N or liver cancer cells considering their EMT status.

Materials and Methods. M1 and M2 macrophages were obtained from THP-1 cell after exposure to PMA followed by LPS/IFNg for M1 or IL4/IL13 for M2. Differentiation was validated by immunofluorescence (IF) using CD14 for monocyte, CD68 for macrophage, CD80 for M1, and CD163 for M2. H&N, cholangiocarcinoma (CK), and hepatocellular carcinoma (HCC) cells were characterized for their EMT status (E-cadherin/vimentin expressions) by western blot. In each tumor type, 1 epithelial and 1 mesenchymal cells were selected to analyze the effects of conditioned medium (CM) from cancer cells on macrophages differentiation, using IF. Furthermore, CCL2 and CSF1 mRNA levels were evaluated in the selected cancer cell lines. In addition, the effect of M1 and M2 CM on cancer cell proliferation, migration, and invasion were also analyzed by MTT, wound-healing, and Boyden chamber assays.

Results. Using our two steps methods, monocytes were first differentiated into macrophages (decrease of CD14 and increase of CD68 expression), and then into M1 and M2 (increase of CD80 or CD163 expression, respectively). Based on cell lines EMT status, SQ20B, SNU1196, and C3A (epithelial) and Hep2, SNU1079, and SKHep1 (mesenchymal) cells were selected. Macrophages exposed to CM from epithelial cells displayed a M1 phenotype, while macrophages exposed to CM from mesenchymal cells exhibited a M2 phenotype. Interestingly, higher mRNA expression of CCL2 and CSF1 mRNA were detected in mesenchymal cells compared to epithelial cells. In H&N and CK cell lines, M1 CM displayed increased antiproliferative effects on epithelial cells, whereas M1 CM displayed antiproliferative effects only on mesenchymal HCC cells. M1 and M2 CM increased migration and invasion in all selected cell lines, except for migration in the epithelial HCC cell line. Further characterization of M1 and M2 macrophages will be displayed at the conference.

Conclusions. This study showed that EMT status of cancer cells modulates macrophages differentiation. In fact, mesenchymal cells showed elevated levels of CCL2 and CSF1 expression, promoting M2 differentiation. Conversely, M1 and M2 displayed differential effects on H&N and liver carcinomas cell lines. These results open up new perspectives on the role of M1/M2 macrophages in EMT-dependent tumors, with the aim of developing new therapeutic approaches for patients with EMT-dependent tumors.

Citation Format: Lucile Astorgues-Xerri, Matthieu Martinet, Eric Raymond, Sandrine Faivre, Annemilaï Tijeras-Raballand. Bidirectional EMT-dependent modulation of cancer cell and M1/M2 macrophage differentiation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5103.

Abstract 1636: Diet-variants and immune characterization of a stage-defined, transgenic immunocompetent mouse model of HCC (ASV-B)

Background: Non-alcoholic fatty liver disease (NAFLD), especially non-alcoholic steatohepatitis (NASH) is a chronic liver disease commonly associated with hepatic fibrosis. NASH patients have an increased risk for hepatocellular carcinoma (HCC). Due to western way of life, NASH incidence is rising and predicted to become the leading cause of liver transplant in 2020 and of HCC in the next decades. There is an urgent need for robust animal models fully recapitulating the NASH-related HCC carcinogenesis due to this changing in HCC etiology. In this study, we develop and characterize specific diet-induced variants from our transgenic HCC mouse model, focusing on immune landscape.

Methods: We used in the whole study ASV-B mice: a transgenic mouse model (C57BL/6J) spontaneously developing a reproducible stage-defined HCC (hyperplasia at week(W)8, nodular stage at W12, and diffuse carcinoma at W16-20). Livers were characterized for angiogenesis and immune populations using immunostaining (IHC and IF), and qRT-PCR (LightCycler, Roche). To mimic NASH, ASV-B mice were exposed to 5 different diets. Ten ASV-B and 5 control mice were fed as follows: classic diet as control (yellow), or a high-fat diet (blue), a diet enriched with saturated fatty acids + 1.25% cholesterol (green), a diet containing 22% of vegetal oil + 0.2% cholesterol (orange), and a 1.25% cholesterol diet containing 21% of milkfat (red). All mice fed with special diets also received 30% fructose in the drink water. A second experiment was performed on ASV-B and C57BL/6J wild type mice, using control and Nash-inducing regimen, to confirm our first results.

Results: ASV-B model showed an increase in liver volume and angiogenesis, HCC livers harboring marked arterialization and capillarization as compared to control. Assessing immune markers on 7 evaluable tumor specimens, we observed an increase in CD8, Foxp3, INOS, CD11b, PD-1, PD-L1, IL1β, IFN-γ, TNF-α, IL17A and IL17F mRNA expressions, as frequently observed in human inflammatory HCC. In addition, IHC staining showed intratumoral infiltration of lymphocytes (CD8+) and macrophages (F4/80+, a well-characterized and extensively referenced mouse macrophage marker). ASV-B mice receiving yellow, blue, and green regimens showed similar liver volumes and weights. By macroscopic analysis, we observed increased liver steatosis, and fibrosis in the red and orange regimen compared to others. Moreover, we observed a 40% mortality rate in the orange regimen, and a 20% mortality rate in the blue and green regimens. Interestingly, by microscopic analysis, we observed liver steatosis and inflammation, in 100%, and 75% of the mice, respectively. These results indicate that the green regimen is the most suitable to induce NASH-underlyning disease in our transgenic HCC model. At the conference, we will show in the diet-variants, the immune landscape of the livers and the results of our ongoing second experiment.

Conclusion: ASV-B transgenic mouse model mimics several characteristics of human HCC developing on healthy liver including inflammatory reaction and immune cell infiltration. In the ASV-B model, we have been able to develop specific-diets variants mimicking NASH characteristics that could be used for drug testing.

Citation Format: Annemilaï Tijeras-Raballand, Christian Hobeika, Philippe Bonnin, Benoit Rousseau, Aurélie Rodrigues, Fouad Ladfil, Marc Pocard, Armand de Gramont, Eric Raymond, Sandrine Faivre, Valérie Paradis, Clarisse Eveno. Diet-variants and immune characterization of a stage-defined, transgenic immunocompetent mouse model of HCC (ASV-B) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1636.

Abstract 899: Remarkable anti-tumor response in a HCC transgenic mouse model treated with GNS561 in combination with anti-PD1

Introduction:Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer, leading to 75,000 deaths annually. Immunotherapeutic intervention has emerged as a novel effective treatment to delay the progression of aggressive tumors and suppress tumor recurrence and metastasis. However, few clinical immunotherapy trials have been conducted in HCC patients and there is an unmet need for novel therapeutic strategies. Combinations of conventional and novel treatments with immune-oncologic agents are now regarded as a therapy that can dramatically improve the outcome of patients with HCC.GNS561 is a lysosomotropic small molecule that was investigated in the context of antitumor activity alone or in combination with a PD-1 inhibitor using a transgenic immunocompetent mouse model (ASV-B).

Materials and Methods: 40 ASV-B mice were treated with either the vehicle (p.o. water pH= 4, 5 days per week), GNS561 (p.o. 50 mg/kg/5 days per week), mouse anti-PD1 antibody (i.p. 10 mg/kg/twice a week [BIW]) or a combination of GNS561 and mouse anti-PD1 (p.o. 50 mg/kg/5 days per week and i.p. 10 mg/kg/BIW respectively) for 8 weeks. Tumor burden was evaluated by measuring the liver volume and blood flow velocity in the coeliac trunk by US/doppler 4 and 8 weeks (W8) after treatment start, the macronodules count and liver weight at sacrifice (W8). Intra and peritumoral CD8+ cells were counted.

Results: All treatments were well tolerated. No significant response was observed with the anti-PD1 monotherapy compared with the vehicle. At W8, GNS561 alone or in combination with an anti-PD-1 showed a significant rapid and durable tumor response based on the macronodule count, decreased liver blood flow in the coeliac trunk, liver volume and weight (-59% and -77%; -18% and -31%; -36% and -37%; -37% and -52%, respectively). Based on preliminary mechanistic data, GNS561 alone or in combination showed an increase in the count of CD8+ cells penetrating the tumor site compared to the vehicle and the anti-PD1 alone, suggesting GNS561 may reinstore the anti-PD1 activity by facilitating CD8+ cells to reach the tumor site to exert their antitumoral activity.

Conclusion: GNS561 alone or in combination with an anti-PD1 showed a significant antitumoral response. A combination of GNS561 with an anti-PD1 could then be of clinical interest in the treatment of hepatocelullar carcinoma.

Citation Format: Madani Rachid, Annemilaï Tijeras-Raballand, Cindy Serdjebi, Sonia Brun, Christelle Ansaldi, Eric Raymond, Philippe Halfon. Remarkable anti-tumor response in a HCC transgenic mouse model treated with GNS561 in combination with anti-PD1 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 899.

Abstract 3684: Basal Notch1 and Notch4 activation as potential markers of aggressiveness and sensitivity to Notch inhibition in human cancer cell lines

Background. Notch pathway is involved in tumor biology including cell proliferation, migration, drug resistance, and epithelial-to-mesenchymal transition (EMT). Notch activation leads to a proteolytic cleavage, followed by the release of the Notch intracellular domain (NICD), which translocates into the nucleus and activates target genes. Notch1 and Notch4 expressions were described as mutually exclusive in some tumors, with an increased aggressiveness linked to low Notch1/high Notch4 expression phenotype. What about the role of their basal activation in cancers? The aim of this work is to characterize the role of basal Notch1 and Notch4 pathway on cell proliferation, motility and sensitivity to Notch inhibition in human pancreatic (PDAC), head&neck (H&N), colorectal (CRC), cholangio (CK), and hepato (HCC) carcinoma cell lines.

Materials and Methods. Cell lines were selected regarding their basal expression of NICD4 using western blot (one low/one high Notch4 basal activation) for each tumor type. Chosen cell lines were then characterized, by western blot and/or RT-qPCR, for Notch signaling (NICD1, HES1, NUMB), EMT status (vimentin, E-cadherin) and survival pathways (pAKT, pERK). Basal cell proliferation and motility were studied using MTT and wound-healing assay. The effects of a Notch inhibitor, PF-03084014, were assessed on cell proliferation and Notch signaling pathway by MTT and western blot.

Results. In PDAC, H&N, and CRC cell lines, high NICD4 expression was associated with low NICD1, HES1, and NUMB expressions, whereas the opposite was observed in low NICD4 expressing cells. Interestingly, all high NICD4/low NICD1 cells displayed a mesenchymal phenotype with high vimentin and low E-cadherin expressions. This phenotype was also associated with an increased proliferation rate and basal cell motility in all tumor types, except for HCC. In addition, basal ERK phosphorylation was increased in the aggressive cells (high NICD4/low NICD1). In PDAC, H&N, and CRC cell lines, PF-03084014 showed higher antiproliferative effects in high NICD4/low NICD1 cells compared to low NICD4/high NICD1 cells. In all cell lines, PF-03084014 displayed no effect on Notch4 activation, but abrogated Notch1 activation in all low NICD4/high NICD1 cells. Interestingly, PF-03084014 decreased HES1 expression in all cells, with increased effects in the most sensitive cells (high NICD4/low NICD1). Further analysis of PF-04084014 effects on cell signaling pathways will be displayed at the conference.

Conclusions. In this study, high Notch4 activation is shown to be correlated with low NICD1, HES1 and NUMB expressions. This phenotype is associated with an increased aggressiveness of human cancer cell lines, and an increased sensitivity to Notch inhibition. As expected, the strongest HES1 inhibition was observed in cell lines with an increased sensitivity to Notch inhibition. Since the inhibition of Notch pathway is an interesting topic for anticancer therapy, this study could help to select tumor types that may be good candidate for Notch inhibitors in the clinics.

Citation Format: Lucile Astorgues-Xerri, Matthieu Martinet, Eric Raymond, Annemilaï Tijeras-Raballand. Basal Notch1 and Notch4 activation as potential markers of aggressiveness and sensitivity to Notch inhibition in human cancer cell lines [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3684.

Abstract 5312: Imeglimin alone or in combination with sorafenib showed potent anti-tumor effect in human hepatocellular carcinoma: A new kid on the block for HCC treatment

Background: Diabetes as a standalone or as part of metabolic syndrome is recognized as a major risk factor in hepatocellular carcinoma (HCC). Metformin one of the most widely used first-line drug for the treatment of type II diabetes showed antitumor activity in preclinical models of HCC, and in some clinical trials. Imeglimin, a first-in-class tetrahydrotriazine oral antidiabetic agents, is currently in phase III clinical trial in diabetes with a good safety profile. Imeglimin stands as an AMPK activator and based on historical data with metformin may be a safe potentially interesting novel therapeutic drugs for patients with HCC. Hence, the current study aims to evaluate the effects of imeglimin alone or in combination with sorafenib compared to metformin in an experimental model of HCC.

Methods: All in vivo experiments were carried out with ethical committee approval and met the standards required by the UKCCCR guidelines. HepG2 HCC cells were injected subcutaneously (2 × 106cells) into the flank of female athymic nude mice. Two weeks after cell inoculation, 90% mice developed single subcutaneous palpable tumors. Mice were randomized in the groups of treatment. Mice were then treated 5 days a week by oral gavage with 75 mg/kg/day metformin (n=14-metformin75), 75 mg/kg/day imeglimin (n=14-Imeglimin75), 150 mg/kg/day imeglimin (n=14-Imeglimin150), 40 mg/kg/day sorafenib (n=14), metformin75 plus sorafenib (n=14) or imeglimin75 plus sorafenib (n=14). Body weight and tumor volumes were assessed thrice a week. Mice were sacrificed after 63 days of treatment to meet ethical requirements (tumor volume < 2000 mm3). Tumor were weighted, excised and OCT-embedded to prevent tissue degradation from frozen conservation.

Results: Our experiments showed a 90% uptake in the engrafted mice. Regardless of the administrated treatment, no toxicity was observed as shown by the body weight follow-up. After 63 days of treatment, each treatment arm showed a slight difference with placebo (n=14). Mean tumor volumes were 1096±208 mm3 (P>0.05), 795±222 mm3 (P>0.05), 563±135 mm3 (P<0.05), and 495±163 mm3(P<0.05) for metformin75 alone, imeglimin75 alone, imeglimin150 alone or sorafenib alone, respectively, versus 1132±156 mm3 in the placebo group. Moreover, the combination of imeglimin75 plus sorafenib (375±121 mm3) displayed an increased antitumor activity compared to metformin75 plus sorafenib (515±112 mm3). In addition, at day 59 of treatment, we reached a tumor growth inhibition of 27%, 49%, and 66% in the imeglimin75 alone, imeglimin150 alone, and combination group imeglimin75 plus sorafenib, respectively. At the time of the meeting, we will be displayed IHC analysis in addition to assess tumor angiogenesis.

Conclusion: This study showed the antitumor effects of imeglimin, a novel AMPK activator in human HCC. Furthermore, imeglimin potentiates the antitumor effects of sorafenib, which may represent an interesting therapeutic option for patients with HCC.

Citation Format: Annemilaï Tijeras-Raballand, Matthieu Martinet, Valérie Paradis, Jean-Pierre Bizzari, Eric Janin, Eric Raymond. Imeglimin alone or in combination with sorafenib showed potent anti-tumor effect in human hepatocellular carcinoma: A new kid on the block for HCC treatment [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5312.

Abstract 1080: Link between M1/M2 human macrophages and epithelial-mesenchymal status in head and neck cancer cell lines

Background. Head and neck carcinoma (H&N) is one of the leading causes of cancer deaths worldwide. Despite advances in diagnosis and treatment, the survival rates remain low mainly due to locoregional relapse, possibly triggered by the activation of epithelial-to-mesenchymal transition (EMT). Recently, several studies have demonstrated a positive link between macrophages, EMT and invasion in H&N cancer. The aim of this study is to analyze the interactions between human antitumoral M1/protumoral M2 macrophages and H&N human cancer cells with different EMT status, with the aim of developing new therapeutic approaches for H&N cancer patients.

Materials and Methods. M1 and M2 macrophages were obtained from THP-1 cell line (human monocyte) after 48h exposure to 25nM of PMA followed by 48h of recovery culture medium, and 72h exposure to 1ng/ml LPS + 20ng/ml IFNγ to obtain M1 phenotype or 20ng/ml IL4 + 20ng/ml IL13 to obtain M2 phenotype. Differentiation status was validated by immunofluorescence (IF) using CD14 for monocyte, CD68 for macrophage, CD80 for M1, and CD163 for M2. Eight H&N cell lines were characterized for their EMT status (E-cadherin/vimentin expression) by western blot. SQ20B (epithelial) and Hep2 (mesenchymal) cell lines were selected to study the effect of M1 and M2 conditioned medium (CM) on cell proliferation. In addition, we also analyzed the effects of CM from SQ20B and Hep2 on macrophages differentiation using IF.

Results. We confirmed the differentiation of monocytes into macrophages by a decrease of CD14 expression and an increase of CD68 expression, and the differentiation of macrophages into M1 and M2 by an increase of CD80 and CD163 expression, respectively. Among the 8 H&N cell lines, 3 cell lines showed an epithelial status (high E-cadherin expression), one a mesenchymal status (high vimentin expression), and 4 a mixed status. Based on these results, we exposed SQ20B (epithelial) and Hep2 (mesenchymal) to M1 or M2 CM. M1 CM strongly inhibited the proliferation of SQ20B cells, with moderate effect on Hep2 cells, whereas M2 CM displayed no effect on SQ20B cells and slightly increased the proliferation of Hep2 cells. Moreover, macrophages exposed to SQ20B CM displayed a M1 phenotype with an increased expression of CD80, whereas Hep2 CM induced a M2 phenotype with an increased expression of CD163.

Conclusions. In vitro, we showed that M1 and M2 macrophages displayed opposite effects on H&N cancer cells proliferation via their conditioned medium, M1 being anti-proliferative and M2 pro-proliferative. These effects were dependent on epithelial/mesenchymal status of cancer cells. In addition, we showed that factors secreted by epithelial vs mesenchymal cancer cells induced macrophages differentiation into M1 and M2, respectively. These results open up new perspectives on the role of M1/M2 macrophages in EMT-dependent H&N cancers and other tumor types such as colon, lung, and liver carcinoma.

Citation Format: Lucile Astorgues-Xerri, Diane Evrard, Matthieu Martinet, Eric Raymond, Sandrine Faivre, Annemilaï Tijeras-Raballand. Link between M1/M2 human macrophages and epithelial-mesenchymal status in head and neck cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1080.

Abstract 859: Basal Notch4 activation is a druggable marker of aggressiveness in a panel of human cancer cell lines

Background: Notch pathway has been involved in cell differentiation, proliferation, apoptosis, angiogenesis and drug resistance, as well as in epithelial-to-mesenchymal transition. Notch pathway activation leads to a proteolytic cleavage, releasing the Notch intracellular domain (NICD), which translocates to the nucleus and activates target genes, such as HES1 (interacting with Notch for maintenance of stem cells and progenitor phenotype). Our team has demonstrated the involvement of PlGF/VEGFR1/Notch4 axis in the angiogenesis of hepatocellular carcinoma, but what about the role of Notch in other cancer types? The aim of this work is to characterize the basal activation and the role of Notch4 in a panel of human cancer cell lines.

Materials and Methods: We characterized a panel of 8 pancreatic (PDAC), 8 head and neck (H&N), 5 colorectal (CRC), 5 cholangiocarcinoma (CK), and 10 hepatocellular (HCC) human carcinoma cell lines for intracellular domain of the notch protein 4 (NICD4), HES1, E-cadherin, and Vimentin expression by Western Blot. In each tumor type, cell lines with high and low Notch4 activation were selected to assess basal cell proliferation and migration, using MTT and wound-healing assay, respectively. In high versus low Notch4 cell lines, we assessed NUMB expression (involved in NICD proteasomal degradation) and the effect of a Notch inhibitor, PF- 03084014.

Results: Notch4 activation assessed by NICD4 expression was observed in 6 out of 8 (6/8) PDAC, 7/8 H&N, 2/5 CRC, 4/5 CK, and 5/10 HCC cell lines. In PDAC cells, Notch4 activation was correlated with high Vimentin expression. In PDAC-, H&N-, CRC-, and CK-low NICD4 cells, we observed an overexpression of NUMB, suggesting a correlation between low Notch4 activation and proteasomal degradation. In most tumor types, Notch4 activation was associated with an increased proliferation rate and basal migration. PF-03084014 had pronounced antiproliferative effects in high NICD4 cells in comparison to low NICD4 cells, except for HCC. In H&N cells, PF-03084014 displayed no effect on Notch4 activation. We also observed a decrease in HES1 expression (significant in high NICD4 cells) and an increased in AKT phosphorylation (significant in low NICD4 cells). We will further analyze the effect of PF-03084014 on cell signaling and migration in other tumor types to display the results at the conference.

Conclusions: In this study, we demonstrated a correlation between high Notch4 basal activation and increased proliferation/migration in a panel of human cancer cell lines, as well as higher sensitivity to the Notch inhibitor PF-03084014. In highly sensitive H&N cell lines, PF-03084014 inhibited Notch signaling pathway, whereas we observed an activation of AKT survival pathway in the low-sensitive ones. Since Notch inhibition is an interesting topic for antitumor therapy, this study could help to select tumor types that could be good candidate for Notch inhibition in the clinic.

Citation Format: Lucile Astorgues-Xerri, Matthieu Martinet, Eric Raymond, Sandrine Faivre, Annemilaï Tijeras-Raballand. Basal Notch4 activation is a druggable marker of aggressiveness in a panel of human cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 859.

Inter- and intra-tumoural heterogeneity in cancer-associated fibroblasts of human pancreatic ductal adenocarcinoma

Cancer‐associated fibroblasts (CAF) are orchestrators of the pancreatic ductal adenocarcinoma (PDAC) microenvironment. Stromal heterogeneity may explain differential pathophysiological roles of the stroma (pro‐ versus anti‐tumoural) in PDAC. We hypothesised that multiple CAF functional subtypes exist in PDAC, that contribute to stromal heterogeneity through interactions with cancer cells. Using molecular and functional analysis of patient‐derived CAF primary cultures, we demonstrated that human PDAC‐derived CAFs display a high level of inter‐ and intra‐tumour heterogeneity. We identified at least four subtypes of CAFs based on transcriptomic analysis, and propose a classification for human PDAC‐derived CAFs (pCAFassigner). Multiple CAF subtypes co‐existed in individual patient samples. The presence of these CAF subtypes in bulk tumours was confirmed using publicly available gene expression profiles, and immunostainings of CAF subtype markers. Each subtype displayed specific phenotypic features (matrix‐ and immune‐related signatures, vimentin and α‐smooth muscle actin expression, proliferation rate), and was associated with an assessable prognostic impact. A prolonged exposure of non‐tumoural pancreatic stellate cells to conditioned media from cancer cell lines (cancer education experiment) induced a CAF‐like phenotype, including loss of capacity to revert to quiescence and an increase in the expression of genes related to CAF subtypes B and C. This classification demonstrates molecular and functional inter‐ and intra‐tumoural heterogeneity of CAFs in human PDAC. Our subtypes overlap with those identified from single‐cell analyses in other cancers, and pave the way for the development of therapies targeting specific CAF subpopulations in PDAC. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Efficacy of aflibercept with FOLFOX and maintenance with fluoropyrimidine as first‑line therapy for metastatic colorectal cancer: GERCOR VELVET phase II study

Aflibercept in combination with 5‑fluorouracil (5‑FU)/irinotecan improves overall survival in the second‑line therapy of patients with metastatic colorectal cancer (mCRC). In this study, we evaluated the effects of aflibercept in first‑line therapy with FOLFOX followed by maintenance with fluoropyrimidine. VELVET was a prospective, single‑arm multicenter phase II study (completed). Patients with previously untreated, unresectable, evaluable or measurable mCRC, with an age ≥18 years, and an ECOG performance status of 0‑2 received 6 cycles of modified FOLFOX7 (5‑FU/folinic acid and oxaliplatin) with aflibercept at 4 mg/kg every 2 weeks followed by maintenance therapy with fluoropyrimidine with aflibercept until disease progression or limiting toxicity. The reintroduction of oxaliplatin was performed at first progression. The primary endpoint was progression‑free survival (PFS) at 6 months. From May, 2013 to May, 2014, 49 patients were included and 48 were evaluable for response. In total, 33 patients (67.4%) were alive without progression at 6 months. The Kaplan‑Meier survival 6‑month and 1‑year PFS rates were 79.1 and 36.1%, respectively, and the median PFS was 9.3 months (95% CI, 8.3‑12.5). The objective response rate was 59.2% (N=29/49). The most common (≥10%) grade 3‑4 adverse events were hypertension (23%), fatigue (15%), neutropenia (12%), neuropathy (12%) and stomatitis (10%). Three (6%) treatment‑related deaths occurred: One from stroke, one from pulmonary embolism and one from neutropenic sepsis. On the whole, this study demonstrates the efficacy of aflibercept in combination with an oxaliplatin‑based regimen in the first‑line therapy of patients with mCRC. A strict monitoring of blood pressure and immediate management of hypertension during therapy is mandatory.

Macrophages in the microenvironment of head and neck cancer: potential targets for cancer therapy

The microenvironment of solid tumors has become a promising target for future therapies modulating immune cells. Patients with advanced head and neck cancer, which still portends a poor outcome, are particularly in need of innovative approaches. In oral squamous cell carcinoma, high density of tumor-associated macrophages (TAMs) appears consistently associated with poor prognosis, whereas data are currently limited for other head and neck sites. Several approaches to block TAMs have been investigated, including TAMs inactivation by means of the colony stimulating factor 1 (CSF-1)/CSF-1 receptor (CSF-1R) inhibitors or strategies to reprogram TAMs from M2 protumoral phenotype toward M1 antitumoral phenotype. This review focuses on both prognostic and therapeutic aspects related to TAMs in head and neck carcinomas.

Abstract 4096: Stage-defined, transgenic immunocompetent mouse model (ASV-B) to investigate new drugs for hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is a complex multistep malignancy in need of new therapeutic options often arising on underlying chronic liver disease. HCC animal models relevant to clinical situations are crucial to investigate new anticancer drugs, alone or in combination. Mice bearing xenografts and transgenic mice are the two main models used for preclinical drug development, but most of them fail to mimic the different step of HCC observed in patients. In this study, we aim to describe a stage-defined, transgenic immunocompetent HCC mouse model.

Methods: ASV-B is a transgenic mouse model that spontaneously develops, upon SV40 T-Ag oncogene expression in hepatocytes, a reproducible stage-defined HCC. Hyperplasia at week(W)8 is followed by nodular stage at W12 (multiple well-delimited tumor nodules of about 1 mm, growing progressively up to 1 cm), then diffuse carcinoma stage at W16-20. HCC is restricted to male, backcrossed with C57BL/6J mice, the female littermates being used as controls.

Results: Liver volume assessed by ultrasound at each step of carcinogenesis showed a 2.7-, 2.7-, 3.9-, and 5.8-fold increase (p<0.001) in transgenic mice compared to controls (CTRL) at W8, 12, 16, and 20, respectively. ASV-B model displays marked arterialization with intense arterial flow in liver tumor similar to human HCC. Sinusoids in tumor nodules are tortuous and dilated, surrounded by activated hepatic stellate cells (HSCs) expressing smooth muscle actin (SMA) while HSCs surrounding normal sinusoids only express desmin. In addition, ASV-B livers develop along carcinogenesis a mesenchymal phenotype (increased vimentin and decreased e-cadherin staining), mimicking certain clinical situations of acquired resistance to VEGFR inhibitors. Angiogenesis, monitored using Doppler assessing blood flow velocity (BFV) in the hepatic artery, is enhanced by 29%, 51% and 156% at W8, W12 and W16, respectively, in transgenic liver animals as compared to CTRL. Increased angiogenesis was confirmed by CD31 staining in tumor specimen showing increased number of vessels per field. ASV-B model has been used to investigate the toxicity and efficacy of new drugs (galunisertib, MET/AXL inhibitor), including antiangiogenic agents (sorafenib and ramucirumab) alone or in combination, and may be relevant to explore the effects of immunotherapy agents. At the conference, we will display further characterization of liver tumors regarding vascularization, and immune cells localization using IHC.

Conclusion: ASV-B transgenic mouse model mimics several characteristics of human HCC developing on healthy liver including multinodular disease, vessel abnormalities, and dedifferentiation toward mesenchymal phenotype. Further steps will consist of characterizing the adjacent nontumor liver, and developing nonalcoolic steatohepatitis (NASH) on ASV-B model using specific diets.

Citation Format: Annemilaï Tijeras-Raballand, Patricia Hainaud, Christian Hobeika, Clarisse Eveno, Marc Pocard, Philippe Bonnin, Valérie Paradis, Mohamed Bouattour, Eric Raymond, Armand de Gramont, Evelyne Dupuy, Sandrine Faivre. Stage-defined, transgenic immunocompetent mouse model (ASV-B) to investigate new drugs for hepatocellular carcinoma [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 4096.

Abstract 2944: TGF-β inhibitor galunisertib combined with antiangiogenic therapies showed antitumor effects in vitro and in vivo in hepatocellular carcinoma (HCC)

Introduction: TGF-β pathway, associated with hepatocellular carcinoma (HCC) progression, can be targeted by galunisertib, a selective ATP-mimetic TGF-β receptor (TβR)-I inhibitor in clinical trials for HCC patients. We investigated the antitumor effects of galunisertib (Galu) combined with antiangiogenic compounds (sorafenib or DC101, a fully human monoclonal antibody antagonizing VEGFR2, mimicking ramucirumab) in HCC.

Methods: In vitro, we assessed proliferation (MTT assay), migration (wound healing), and invasion (boyden chambers), in a panel of HCC cell lines. Transgenic mice developing stage-defined HCC were treated from weeks (W)8 to W16 with either vehicle, sorafenib (30mg/kg), Galu (100mg/kg), sorafenib plus Galu, DC101 (40mg/kg, twice weekly, IP), or DC101 plus galunisertib. Tumor growth was evaluated by ultrasound (liver size) and by the number of macronodules at sacrifice. Angiogenesis assessed by Doppler measuring the mean blood flow in the coeliac trunk (TCm) and CD31 staining.

Results: In vitro, we showed an inhibition of TGF-induced proliferation, migration and proliferation by Galu, further potentiated by sorafenib. Sorafenib-tolerant cell line SK-Sora was the most sensitive to Galu. In vivo, at W12 & W16, liver size and tumor macronodules number were significantly lower in all treatment arms compared to placebo. At W16, DC101 showed increased tumor control compared to sorafenib regarding liver weight (3,75g±0,39 vs 6,31 g±0,52, p<0.001) and macronodules number (75,7±12.0 vs 139±13,6, p<0.001). Galu/sorafenib and Galu/DC101 combinations showed increased tumor control at W16 as compared to monotherapies. Interestingly, at W16, Galu/DC101 combination showed greater effect on liver weight (3,09g±0,70 vs 3.75g±0,21, p<0.05, number of macronodules (55.1±14.8 vs 109.4±24.3, p<0.001), and micronodules surface (2.0 mm2±0.43 vs 1.43 mm2±0.33, p<0.05) as compared to Galu/sorafenib combination. Angiogenesis decreased in all treatment arms compared to placebo. At W16, we observed a TCm decrease over 50% in the combination arms compared to 24% with sorafenib, 26% with DC101 and 20% with Galu alone, respectively. These results were confirmed by CD31 staining for assessing number of vessels per field. In addition, Galu/sorafenib combination yielded an increased number of monocytes, a decreased number of neutrophils and Kuppfer cells, along with increased NK cells and decreased NKT cells. Dendritic cells as well as B and T cells population did not show particular variation except for CD4+CD25+ T cells that were strongly decreased in sorafenib-treated mice.

Conclusion: The combination of galunisertib with sorafenib or DC101 showed promising antitumor activities that were associated with decreased angiogenesis, DC101 displaying increased efficacy as compared to sorafenib.

Citation Format: Annemilaï Tijeras-Raballand, Christian Hobeika, Matthieu Martinet, Lucile Astorgues-Xerri, Elise Paven, Marie-Aude Le Bitoux, Anne Maillard, Clarisse Eveno, Marc Pocard, Philippe Bonnin, Alexandre Harari, Eric Raymond, Sandrine Faivre, Armand de Gramont. TGF-β inhibitor galunisertib combined with antiangiogenic therapies showed antitumor effects in vitro and in vivo in hepatocellular carcinoma (HCC) [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 2944.

Abstract 2501: Involvement of Notch signaling pathway in a panel of human cancer cell lines

Background. Notch pathway has been involved in cell fate determination, cell differentiation, cell proliferation, apoptosis, angiogenesis and drug resistance, as well as epithelial-to-mesenchymal transition (EMT). Our team has demonstrated the involvement of the PlGF/VEGFR1/Notch4 axis in the angiogenesis of HCC, but what about the role of Notch in cancer cells? In this study, we will focus on Notch1 and Notch4 since they have been extensively described in tumor angiogenesis. The aim of this work is to characterize the expression and the role of basal Notch1 and Notch4 activation in a panel of human cancer cell lines.

Materials and Methods. We characterized a panel of 8 pancreatic, 5 cholangiocarcinoma (CK), 5 colorectal, 8 head and neck (H&N), and 5 hepatocellular (HCC) human cancer cell lines for Notch1, Notch4, E-cadherin, and Vimentin expressions by Western Blot. In each cancer type, 2 cell lines were chosen (one each with high and low Notch expression, respectively) to further assess the role of Notch basal expression in cellular properties such as migration, invasion, and vasculogenic mimicry, by using wound-healing test, Boyden chamber assay, and Ibidi plates, respectively. We also studied the effects of Notch inhibition on those cellular activities.

Results. Our first results showed that Notch1 and Notch4 are activated in most of cancer cell lines at basal state. Notch4 is highly activated in 6 out of 8 pancreas cell lines, 7 out of 8 H&N cell lines, 2 out of 3 HCC cell lines, 3 out of 5 CK cell lines, and 2 out of 5 colon cell lines. In contrast, Notch1 is activated in all the CK cells, 3 out of 8 H&N cell lines, and 2 out of 3 HCC cell lines. Interestingly, in pancreatic and HCC cell lines, Notch4 activation is correlated with high expression of Vimentin. These results raised the question of the implication of Notch basal activation in the aggressiveness of tumor cells. Thus, we will further investigate the role of Notch1 and Notch4 in migration and invasion properties of tumor cells. Furthermore, since Notch1 and Notch4 are widely described in angiogenesis, we will also assess the vasculogenic mimicry properties of tumor cell with high versus low basal activation of Notch1 and Notch4. These results will be displayed at the conference.

Conclusions. In this study, we show the high prevalence of Notch1 and Notch4 basal activation in a large panel of cancer cells lines, suggesting its role in cellular activities of cancer cells. Since Notch inhibition is currently an interesting topic for antitumor therapy, this study could help to discriminate the tumor types or tumor characteristics that are good candidate for Notch inhibition in the clinics.

Citation Format: Lucile Astorgues-Xerri, Mathieu Martinet, Jinan Abdullah, Sandrine Faivre, Eric Raymond, Annemilaï Tijeras-Raballand. Involvement of Notch signaling pathway in a panel of human cancer cell lines [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 2501.

Everolimus affects vasculogenic mimicry in renal carcinoma resistant to sunitinib

Angiogenesis is hallmark of clear cell renal cell carcinogenesis. Anti-angiogenic therapies have been successful in improving disease outcome; however, most patients treated with anti-angiogenic agents will eventually progress. In this study we report that clear cell renal cell carcinoma was associated with vasculogenic mimicry in both mice and human with tumor cells expressing endothelial markers in the vicinity of tumor vessels. We show that vasculogenic mimicry was efficiently targeted by sunitinib but eventually associated with tumor resistance and a more aggressive phenotype both in vitro and in vivo. Re-challenging these resistant tumors in mice, we showed that second-line treatment with everolimus particularly affected vasculogenic mimicry and tumor cell differentiation compared to sorafenib and axitinib. Finally, our results highlighted the phenotypic and genotypic changes at the tumor cell and microenvironment levels during sunitinib response and progression and the subsequent improvement second-line therapies bring to the current renal cell carcinoma treatment paradigm.

Abstract B57: Effects of MEK inhibition alone or in combination with PI3K-mTOR pathway inhibitors in pancreatic ductal adenocarcinoma in vitro and on an innovative ex vivo fresh tumor tissue culture model

Purpose: Activating KRAS mutations are frequent (>90%) in pancreatic ductal adenocarcinoma (PDAC) and drive downstream deregulation of both MAPK and PI3K-mTOR pathways. MEK inhibitors (MEKi) are under clinical evaluation in PDAC, in combination with other agents including PI3K-mTOR inhibitors. While RAS and BRAF mutations, EMT, PI3K-mTOR activation, and pERK inhibition have been suggested as predictive markers for MEKi efficacy, they are not validated in PDAC. We aimed to explore the cellular and molecular effects of MEKi GSK1120212 (GSK212) alone or in combination with PI3K-mTOR inhibitors, in PDAC cell lines and on an innovative ex vivo system.

Methods: GSK212 is an allosteric non-ATP competitive MEKi, everolimus (Ev) a mTORC1 inhibitor, and BKM120 a pan-class PI3K inhibitor. Effects on proliferation were evaluated by MTT assay. Combinations were analyzed by the Chou-Talalay method. Protein expression was assessed by Western blot. Ex vivo drug assays were performed at different drug concentrations on cultures of fresh tumor tissue slices prepared from patient surgical specimens. Apoptosis and proliferation were assessed by cleaved caspase 3 (Cas-3) and MIB-1 (Ki67) immunostainings, respectively; MEKi sensitivity was defined as cleaved Cas-3 expression in 30% or more of cancer cells. Correlations between protein expressions were explored using linear regression and Pearson’s R2 calculation. Samples will be classified into PDAC subtypes according to Collisson’s, Moffit’s and Bailey’s transcriptomic signatures using non-negative matrix factorization and correlation methods.

Results: MIAPaCa-2 and PANC-1 are two mesenchymal KRAS mutated/BRAF wild-type PDAC cell lines with very different response to GSK212, MIAPaCa-2 being sensitive (72h-IC50=0.009µM) and PANC-1 resistant (72h-IC50=33µM). MIAPaCa-2 was more sensitive than PANC-1 to Ev (IC50=23.3µM vs 47.0µM) and BKM120 (IC50=4.19µM vs 31.6µM). Combination of GSK212 and Ev or BKM120 for 72h resulted in synergistic effects (CI<1) in MIAPaCa-2 (MEKi sensitive) but not in PANC-1. GSK212 (0.1µM) treatment resulted in pERK extinction in both cell lines but in decreased pS6 expression only in MIAPaCa-2. Combination therapy led to extinction of pERK and pS6 in both cell lines. Apoptosis induction in MIAPaCa-2 was confirmed by PARP cleavage. Eleven tumor specimens were cultured ex vivo. We observed that: (a) GSK212 (0.1µM) treatment for 48h induced significant (≥30%) apoptosis concomitantly with a decrease in pS6 expression in MEKi sensitive tumors; (b) Ev (1µM) or BKM120 (0.1µM) exerted antiproliferative effects but did not induce apoptosis; (c) combinations resulted in higher apoptosis induction associated with a higher decrease in pS6 expression compared to MEKi alone in MEKi sensitive tumors. In sensitive tumors, cleaved Cas-3 induction was inversely correlated with pS6 expression under treatment by MEKi +/- Ev or BKM120. A R2>0.50 discriminated between sensitive and resistant tumors. There was no correlation with RAS/RAF mutation status. Predictive value of transcriptomic signatures for MEKi response will be presented.

Conclusion: Response to combined MEK/mTOR pathway inhibition was not correlated with known biomarkers of response to MEKi. Besides the therapeutic potential of MEK/mTOR pathway inhibition in PDAC, this work provides the first evidence of feasibility of pharmacodynamic biomarker monitoring on fresh PDAC tissue slices.

Citation Format: Cindy Neuzillet, Annemilaï Tijeras-Raballand, Anguraj Sadanandam, Pierre Bourgoin, Philippe Bourget, Pawan Poudel, Maria Serova, Armand De Gramont, Philippe Ruszniewski, Valérie Paradis, Eric Raymond, Jérôme Cros, Pascal Hammel.{Authors}. Effects of MEK inhibition alone or in combination with PI3K-mTOR pathway inhibitors in pancreatic ductal adenocarcinoma in vitro and on an innovative ex vivo fresh tumor tissue culture model. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B57.

Adjuvant Fluorouracil, Leucovorin, and Oxaliplatin in Stage II to III Colon Cancer: Updated 10-Year Survival and Outcomes According to BRAF Mutation and Mismatch Repair Status of the MOSAIC Study

Purpose

The MOSAIC (Multicenter International Study of Oxaliplatin/Fluorouracil/Leucovorin in the Adjuvant Treatment of Colon Cancer) study has demonstrated 3-year disease-free survival (DFS) and 6-year overall survival (OS) benefit of adjuvant oxaliplatin in stage II to III resected colon cancer. This update presents 10-year OS and OS and DFS by mismatch repair (MMR) status and BRAF mutation.

Methods

Survival actualization after 10-year follow-up was performed in 2,246 patients with resected stage II to III colon cancer. We assessed MMR status and BRAF mutation in 1,008 formalin-fixed paraffin-embedded specimens.

Results

After a median follow-up of 9.5 years, 10-year OS rates in the bolus/infusional fluorouracil plus leucovorin (LV5FU2) and LV5FU2 plus oxaliplatin (FOLFOX4) arms were 67.1% versus 71.7% (hazard ratio [HR], 0.85; P = .043) in the whole population, 79.5% versus 78.4% for stage II (HR, 1.00; P = .980), and 59.0% versus 67.1% for stage III (HR, 0.80; P = .016) disease. Ninety-five patients (9.4%) had MMR-deficient (dMMR) tumors, and 94 (10.4%) had BRAF mutation. BRAF mutation was not prognostic for OS (P = .965), but dMMR was an independent prognostic factor (HR, 2.02; 95% CI, 1.15 to 3.55; P = .014). HRs for DFS and OS benefit in the FOLFOX4 arm were 0.48 (95% CI, 0.20 to 1.12) and 0.41 (95% CI, 0.16 to 1.07), respectively, in patients with stage II to III dMMR and 0.50 (95% CI, 0.25 to 1.00) and 0.66 (95% CI, 0.31 to 1.42), respectively, in those with BRAF mutation.

Conclusion

The OS benefit of oxaliplatin-based adjuvant chemotherapy, increasing over time and with the disease severity, was confirmed at 10 years in patients with stage II to III colon cancer. These updated results support the use of FOLFOX in patients with stage III disease, including those with dMMR or BRAF mutation.

State of the art and future directions of pancreatic ductal adenocarcinoma therapy

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second cause of cancer-related death in 2030. PDAC is the poorest prognostic tumor of the digestive tract, with 80% of patients having advanced disease at diagnosis and 5-year survival rate not exceeding 7%. Until 2010, gemcitabine was the only validated therapy for advanced PDAC with a modest improvement in median overall survival as compared to best supportive care (5-6 vs 3 months). Multiple phase II-III studies have used various combinations of gemcitabine with other cytotoxics or targeted agents, most in vain, in attempt to improve this outcome. Over the past few years, the landscape of PDAC management has undergone major and rapid changes with the approval of the FOLFIRINOX and gemcitabine plus nab-paclitaxel regimens in patients with metastatic disease. These two active combination chemotherapy options yield an improved median overall survival (11.1 vs 8.5 months, respectively) thus making longer survival a reasonably achievable goal. This breakthrough raises some new clinical questions about the management of PDAC. Moreover, better knowledge of the environmental and genetic events that underpin multistep carcinogenesis and of the microenvironment surrounding cancer cells in PDAC has open new perspectives and therapeutic opportunities. In this new dynamic context of deep transformation in basic research and clinical management aspects of the disease, we gathered updated preclinical and clinical data in a multifaceted review encompassing the lessons learned from the past, the yet unanswered questions, and the most promising research priorities to be addressed for the next 5 years.

Abstract 794: Prognostic value of high c-Met expression in patients with poor prognosis pancreatic adenocarcinoma following surgical resection: comparison of three c-Met scoring methods and exploration of underlying mechanisms of c-Met overexpression

Context: The HGF/c-Met pathway is an hypoxia-inducible pathway involved in tumor-stroma interactions and invasion in pancreatic ductal adenocarcinoma (PDAC). Assessment of c-Met expression is a critical issue as c-Met inhibitors are under clinical development and are suggested to display antitumor activity only in high c-Met tumors. We aimed to assess the prognostic value of c-Met overexpression in PDAC and explore underlying mechanisms (hypoxia, gene amplification, post transcriptional deregulation).

Patients and methods: Patients (Pts) with resected PDAC who had received no perioperative chemo/radiotherapy were retrospectively selected. c-Met immunostaining was graded using a simplified score (high c-Met: ≥20% of cancer cells with 3+ staining) and compared to a standard scale combining staining surface and intensity (SI score) and to the MetMab score. Concordance between entire section and tissue microarray (TMA) was assessed and a computer-assisted quantification algorithm was developed (Aperio® software). Hypoxia was assessed by visual grading of HIF-1α/CA9 immunostaining, necrosis, and automated microvascular density (Aperio®). c-Met gene copy number was assessed by fluorescent in situ hybridization (FISH) and Taqman® based copy number variation (CNV) assay. c-Met mRNA levels were quantified using reverse transcription PCR (RT-PCR). c-Met pathway activation was assessed by immunostaining of phospho-c-Met, phospho-GAB1 and downstream signaling (pAKT, pERK, and pSTAT3) and graded visually. Clinical, pathological, and molecular biomarkers were correlated with disease-free (DFS) and overall (OS) survivals.

Results: Thirty-seven Pts were analyzed. The simplified c-Met score displayed the best prognostic value and reproducibility vs both the SI score and the MetMab score; using this score: (a) high c-Met (7/37) was associated with shorter DFS (6.3 vs 33.0 months, HR: 3.456, p = 0.0035) and OS (10.8 vs 39.0 months, HR: 4.257, p = 0.0006); and (b) the kappa index was 0.773±0.122. In multivariate analysis, high c-Met was independently associated with both DFS and OS. c-Met expression was concordant on entire section and TMA in 87.9% of cases, and quantifiable using a specific computer-assisted algorithm. There was no correlation between hypoxia-related markers and c-Met expression. FISH and CNV analysis did not show c-Met gene amplification. mRNA quantification and downstream pathway activation data will be presented.

Conclusion: c-Met is an independent prognostic marker in resected PDAC that may help identifying Pts at high risk of recurrence and poor survival. High c-Met expression was not associated with hypoxia or gene amplification in this study. The simplified c-Met scale is a robust and reproducible scoring method that could be used for ongoing larger studies on TMA.

Citation Format: Cindy Neuzillet, Annemilaï Tijeras-Raballand, Jérôme Raffenne, Armand de Gramont, Pierre Bedossa, Valérie Paradis, Alain Sauvanet, Jean-Baptiste Bachet, Eric Raymond, Pascal Hammel, Anne Couvelard, Jérôme Cros. Prognostic value of high c-Met expression in patients with poor prognosis pancreatic adenocarcinoma following surgical resection: comparison of three c-Met scoring methods and exploration of underlying mechanisms of c-Met overexpression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 794. doi:10.1158/1538-7445.AM2015-794

Abstract 2677: Decrease in phospho-S6 expression under MEK inhibitor (MEKi) treatment as a potential predictive biomarker of response to MEKi alone or in combination with PI3K-mTOR pathway inhibitor in pancreatic adenocarcinoma in vitro and ex vivo models

Context: Activating KRAS mutations are frequent (>90%) in PDAC and drive downstream deregulation of both MAPK and PI3K-mTOR pathways. MEK inhibitors (MEKi) are under clinical evaluation in PDAC, in combination with other agents including PI3K-mTOR inhibitors. RAS and BRAF mutations, EMT, PI3K-mTOR activation, and pERK inhibition under treatment have been suggested as predictive markers for MEKi, but remain unvalidated in PDAC. We explored the cellular and molecular effects of MEKi GSK1120212 (GSK212) alone or in combination with PI3K-mTOR inhibitors, in PDAC cell lines and ex vivo culture system.

Material and methods: GSK212 is an allosteric non-ATP competitive MEKi. Everolimus (Ev) is a mTORC1 inhibitor and BKM120 a pan-class PI3K inhibitor. Effects on proliferation were evaluated by MTT assay. Combinations were analyzed by the Chou-Talalay method. Protein expression was assessed by Western blot. Ex vivo drug evaluation used selected concentrations of drugs on cultures of fresh tissue slices from patient surgical specimens. Apoptosis and proliferation were evaluated by caspase 3 and MIB-1 (Ki67) immunostaining, respectively. Correlations between protein expressions were explored using linear regression.

Results: MIAPaCa-2 and PANC-1 are two mesenchymal KRAS mutated/BRAF wild-type PDAC cell lines with very different response to GSK212, MIAPaCa-2 being sensitive (72h-IC50 = 0.009μM) and PANC-1 resistant (72h-IC50 = 33μM). MIAPaCa-2 was more sensitive than PANC-1 to Ev (IC50 = 23.3μM vs 47.0μM) and BKM120 (IC50 = 4.19μM vs 31.6μM). Combination of GSK212 and Ev or BKM120 for 72h resulted in synergistic effects in MIAPaCa-2 sensitive cell line but not in PANC-1. GSK212 (0.1μM) treatment resulted in pERK extinction in both cell lines but in decreased pS6 expression in MIAPaCa-2 sensitive cell line only. Combination therapy resulted in extinction of pERK and pS6 expression in both cell lines. Apoptosis induction in MIAPaCa-2 was confirmed by PARP cleavage from 48h. Two tumor specimens were cultured ex vivo: (a) GSK212 (0.1 μM) treatment for 48h induced apoptosis (caspase 3 expression) concomitantly with a decrease in pS6 expression; (b) Ev (1μM) or BKM120 (0.1μM) exerted antiproliferative effects but did not induce apoptosis; (c) combinations resulted in higher caspase 3 expression associated with a higher decrease in pS6 expression compared to MEKi alone. Linear regression showed significant correlation between caspase 3 and pS6 (R2 = 0.5798, p = 0.0282, and R2 = 0.9423, p = 0.013, for tumor 1 and 2, respectively).

Conclusion: Response to combined MEK/mTOR pathway inhibition was not correlated with “classical” biomarkers of response to MEKi. Decrease in pS6 expression under MEKi treatment may be an early monitoring biomarker of response to MEKi and MEK/mTOR pathway inhibitor combination.

Citation Format: Cindy Neuzillet, Annemilaï Tijeras-Raballand, Jérôme Cros, Pierre Bourgoin, Philippe Bourget, Maria Serova, Armand De Gramont, Sandrine Faivre, Eric Raymond, Philippe Ruszniewski, Pascal Hammel. Decrease in phospho-S6 expression under MEK inhibitor (MEKi) treatment as a potential predictive biomarker of response to MEKi alone or in combination with PI3K-mTOR pathway inhibitor in pancreatic adenocarcinoma in vitro and ex vivo models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2677. doi:10.1158/1538-7445.AM2015-2677

Targeting cancer cell metabolism in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of cancer death by 2030. Current therapeutic options are limited, warranting an urgent need to explore innovative treatment strategies. Due to specific microenvironment constraints including an extensive desmoplastic stroma reaction, PDAC faces major metabolic challenges, principally hypoxia and nutrient deprivation. Their connection with oncogenic alterations such as KRAS mutations has brought metabolic reprogramming to the forefront of PDAC therapeutic research. The Warburg effect, glutamine addiction, and autophagy stand as the most important adaptive metabolic mechanisms of cancer cells themselves, however metabolic reprogramming is also an important feature of the tumor microenvironment, having a major impact on epigenetic reprogramming and tumor cell interactions with its complex stroma. We present a comprehensive overview of the main metabolic adaptations contributing to PDAC development and progression. A review of current and future therapies targeting this range of metabolic pathways is provided.

Abstract A107: c-Met overexpression as an independent prognostic biomarker and therapeutic target in patients with poor prognostic pancreatic adenocarcinoma following surgical resection

Context: Hypoxia-induced activation of the HGF/c-Met pathway is involved in tumor-stroma interactions and invasion in pancreatic ductal adenocarcinoma (PDAC). Assessment of c-Met expression is a critical issue as c-Met inhibitors are under clinical development in PDAC.

Patients and methods: Patients with resected PDAC and no perioperative chemotherapy/radiotherapy were retrospectively selected to assess the “pure” prognostic value of molecular biomarkers. c-Met immunostaining was graded using a standard visual scale combining surface (S) and intensity (I) (SI) or a simplified score (high c-Met: ≥20% of cancer cells with strong staining). Hypoxia was assessed by HIF-1α and CA9 immunostainings, CD31 expression (microvascular density), and necrosis. Clinical, pathological, and molecular biomarkers were correlated with disease-free (DFS) and overall (OS) survivals. Computer-assisted classification was performed using Aperio® software. Patients with resected PDAC who had received adjuvant treatment (chemotherapy and/or radiotherapy) were selected for the validation step of c-Met score on tissue microarrays (TMA).

Results: Thirty-seven patients were analyzed. The simplified score had the best prognostic value and reproducibility. Using this score, high c-Met expression (7/37) was associated with shorter DFS (6.3 vs 33.0 months, HR: 3.456, p=0.0036) and OS (10.8 vs 39.0 months, HR: 4.257, p=0.0004). In multivariate analysis, high c-Met expression was independently associated with both DFS (p=0.030) and OS (p=0.004). c-Met expression was concordant on entire section and TMA in 87.9%, and quantifiable using a specific computer-assisted algorithm (36/37 tumors were correctly classified). There was no correlation between hypoxia-related markers and c-Met expression in this study. In the validation cohort (n=94), patients with c-Met high tumors had significantly shorter DFS (9.4 vs 18.4 months, HR: 1.830, p=0.0198).

Conclusion: c-Met is an independent prognostic marker in resected PDAC that may help identifying patients at high risk of recurrence and poor survival. The simplified c-Met scale is robust and reproducible, and could be used as reliable scoring method for routine use and larger prognostic and predictive studies on TMA. Patients with PDAC overexpressing c-Met may represent a subgroup candidate for intensified adjuvant treatment or clinical trials with c-Met inhibitors.

Citation Format: Cindy Neuzillet, Jérôme Cros, Annemilaï Tijeras-Raballand, Armand De Gramont, Julien Moroch, Louis De Mestier, Pierre Bedossa, Valérie Paradis, Alain Sauvanet, Jean-Baptiste Bachet, Esteban Cvitkovic, Eric Raymond, Pascal Hammel, Anne Couvelard. c-Met overexpression as an independent prognostic biomarker and therapeutic target in patients with poor prognostic pancreatic adenocarcinoma following surgical resection. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A107.

High c-Met expression in stage I-II pancreatic adenocarcinoma: proposal for an immunostaining scoring method and correlation with poor prognosis

AIMS

c-Met is an emerging biomarker in pancreatic ductal adenocarcinoma (PDAC); there is no consensus regarding the immunostaining scoring method for this marker. We aimed to assess the prognostic value of c-Met overexpression in resected PDAC, and to elaborate a robust and reproducible scoring method for c-Met immunostaining in this setting.

METHODS AND RESULTS

c-Met immunostaining was graded according to the validated MetMab score, a classic visual scale combining surface and intensity (SI score), or a simplified score (high c-Met: ≥ 20% of tumour cells with strong membranous staining), in stage I-II PDAC. A computer-assisted classification method (Aperio software) was developed. Clinicopathological parameters were correlated with disease-free survival (DFS) and overall survival(OS). One hundred and forty-nine patients were analysed retrospectively in a two-step process. Thirty-seven samples (whole slides) were analysed as a pre-run test. Reproducibility values were optimal with the simplified score (kappa = 0.773); high c-Met expression (7/37) was associated with shorter DFS [hazard ratio (HR) 3.456, P = 0.0036] and OS (HR 4.257, P = 0.0004). c-Met expression was concordant on whole slides and tissue microarrays in 87.9% of samples, and quantifiable with a specific computer-assisted algorithm. In the whole cohort (n = 131), patients with c-Met(high) tumours (36/131) had significantly shorter DFS (9.3 versus 20.0 months, HR 2.165, P = 0.0005) and OS (18.2 versus 35.0 months, HR 1.832, P = 0.0098) in univariate and multivariate analysis.

CONCLUSIONS

Simplified c-Met expression is an independent prognostic marker in stage I-II PDAC that may help to identify patients with a high risk of tumour relapse and poor survival.

Effects of preset sequential administrations of sunitinib and everolimus on tumour differentiation in Caki-1 renal cell carcinoma

BACKGROUND

Sunitinib (VEGFR/PDGFR inhibitor) and everolimus (mTOR inhibitor) are both approved for advanced renal cell carcinoma (RCC) as first-line and second-line therapy, respectively. In the clinics, sunitinib treatment is limited by the emergence of acquired resistance, leading to a switch to second-line treatment at progression, often based on everolimus. No data have been yet generated on programmed alternating sequential strategies combining alternative use of sunitinib and everolimus before progression. Such strategy is expected to delay the emergence of acquired resistance and improve tumour control. The aim of our study was to assess the changes in tumours induced by three different sequences administration of sunitinib and everolimus.

METHODS

In human Caki-1 RCC xenograft model, sunitinib was alternated with everolimus every week, every 2 weeks, or every 3 weeks. Effects on necrosis, hypoxia, angiogenesis, and EMT status were assessed by immunohisochemistry and immunofluorescence.

RESULTS

Sunitinib and everolimus programmed sequential regimens before progression yielded longer median time to tumour progression than sunitinib and everolimus monotherapies. In each group of treatment, tumour growth control was associated with inhibition of mTOR pathway and changes from a mesenchymal towards an epithelial phenotype, with a decrease in vimentin and an increase in E-cadherin expression. The sequential combinations of these two agents in a RCC mouse clinical trial induced antiangiogenic effects, leading to tumour necrosis.

CONCLUSIONS

In summary, our study showed that alternate sequence of sunitinib and everolimus mitigated the development of mesenchymal phenotype compared with sunitinib as single agent.

Perspectives of TGF-β inhibition in pancreatic and hepatocellular carcinomas

Advanced pancreatic ductal adenocarcinoma (PDAC) and hepatocellular carcinoma (HCC) are non-curable diseases with a particularly poor prognosis. Over the last decade, research has increasingly focused on the microenvironment surrounding cancer cells, and its role in tumour development and progression. PDAC and HCC differ markedly regarding their pathological features: PDAC are typically stromal-predominant, desmoplastic, poorly vascularized tumours, whereas HCC are cellular and highly vascularized. Despite these very different settings, PDAC and HCC share transforming growth factor-β (TGF-β) as a common key-signalling mediator, involved in epithelial-to-mesenchymal transition, invasion, and stroma-tumour dialogue. Recently, novel drugs blocking the TGF-β pathway have entered clinical evaluation demonstrating activity in patients with advanced PDAC and HCC. TGF-β signalling is complex and mediates both pro- and anti-tumoural activities in cancer cells depending on their context, in space and time, and their microenvironment. In this review we provide a comprehensive overview of the role of the TGF-β pathway and its deregulation in PDAC and HCC development and progression at the cellular and microenvironment levels. We also summarize key preclinical and clinical data on the role of TGF-β as a target for therapeutic intervention in PDAC and HCC, and explore perspectives to optimize TGF-β inhibition therapy.

Stromal expression of SPARC in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) stands as the poorest prognostic tumor of the digestive tract, with a 5-year survival rate of less than 5%. Therapeutic options for unresectable PDAC are extremely limited and there is a pressing need for expanded therapeutic approaches to improve current options available with gemcitabine-based regimens. With PDAC displaying one of the most prominent desmoplastic stromal reactions of all carcinomas, recent research has focused on the microenvironment surrounding PDAC cells. Secreted protein acid and rich in cysteine (SPARC), which is overexpressed in PDAC, may display tumor suppressor functions in several cancers (e.g., in colorectal, ovarian, prostate cancers, and acute myelogenous leukemia) but also appears to be overexpressed in other tumor types (e.g., breast cancer, melanoma, and glioblastoma). The apparent contradictory functions of SPARC may yield inhibition of angiogenesis via inhibition of vascular endothelial growth factor, while promoting epithelial-to-mesenchymal transition and invasion through matrix metalloprotease expression. This feature is of particular interest in PDAC where SPARC overexpression in the stroma stands along with inhibition of angiogenesis and promotion of cancer cell invasion and metastasis. Several therapeutic strategies to deplete stromal tissue have been developed. In this review, we focused on key preclinical and clinical data describing the role of SPARC in PDAC biology, the properties, and mechanisms of delivery of drugs that interact with SPARC and discuss the proof-of-concept clinical trials using nab-paclitaxel.

Targeting the TGFβ pathway for cancer therapy

The TGFβ signaling pathway has pleiotropic functions regulating cell growth, differentiation, apoptosis, motility and invasion, extracellular matrix production, angiogenesis, and immune response. TGFβ signaling deregulation is frequent in tumors and has crucial roles in tumor initiation, development and metastasis. TGFβ signaling inhibition is an emerging strategy for cancer therapy. The role of the TGFβ pathway as a tumor-promoter or suppressor at the cancer cell level is still a matter of debate, due to its differential effects at the early and late stages of carcinogenesis. In contrast, at the microenvironment level, the TGFβ pathway contributes to generate a favorable microenvironment for tumor growth and metastasis throughout all the steps of carcinogenesis. Then, targeting the TGFβ pathway in cancer may be considered primarily as a microenvironment-targeted strategy. In this review, we focus on the TGFβ pathway as a target for cancer therapy. In the first part, we provide a comprehensive overview of the roles played by this pathway and its deregulation in cancer, at the cancer cell and microenvironment levels. We go on to describe the preclinical and clinical results of pharmacological strategies to target the TGFβ pathway, with a highlight on the effects on tumor microenvironment. We then explore the perspectives to optimize TGFβ inhibition therapy in different tumor settings.

Abstract 1812: XCE853: A novel PDI inhibitor that inhibits proliferation of human tumor cells in vitro, ex-vivo and in vivo

XCE853 was originally identified within a family of synthetic compounds displaying a preferential antiproliferative activity on drug resistant human cancer cells (Gutmann et al, AACR annual meeting, 2013). XCE853 induced an irreversible cytolysis of human tumor cells after a short in vitro exposure independently of efflux pumps leading to a tumor cell death by autophagy and particles release (vesicles or protein aggregates).

The interest for XCE853 has been reinforced by three in vitro observations: 1) XCE853 inhibits the recombinant human enzyme PDI recognized as one novel target linked to drug resistance 2) XCE853 has a unique antiproliferative profile compared to the NCI database compounds when using the NCI Compare assay and 3) XCE853 has no activity on human normal prostate cells even at high concentrations whereas XCE shows an IC50 in the nanomolar range on human tumoral cells.

In addition, the ex-vivo approach using fresh human tumor explants cultivated in 3 dimensions with low concentrations of XCE853 has shown a strong decrease of the proliferation (KI-67 labeling) with an apoptosis induction (Caspase-3 labeling) of Head & Neck cancers following 24h of exposure.

Finally, XCE853 which displayed an excellent oral bioavailability in mouse is able to block growth of human ovarian cancer using in vivo xenograft model leading to a complete tumor growth arrest even after the stop of the treatment.

Altogether, these data support further efforts on this drug candidate to initiate the preclinical studies and to define the most relevant human tumor types.

Citation Format: Gregoire P. Prevost, Shili Xu, Marine Garrido, Maria Serova, Olivier DE Vewer, Christian Gespach, Jean-François Briand, Annemilaï Tijeras-Raballand, Mathieu Gutmann, An Hendrix, Michele Sabbah, Anne Chachereau, Armand de Gramont, Nouri Neamati, Denis Carniato, Marc-Henry Pitty, Paul Foster. XCE853: A novel PDI inhibitor that inhibits proliferation of human tumor cells in vitro, ex-vivo and in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1812. doi:10.1158/1538-7445.AM2014-1812

OTX008, a selective small-molecule inhibitor of galectin-1, downregulates cancer cell proliferation, invasion and tumour angiogenesis

BACKGROUND

Galectin-1 (Gal1), a carbohydrate-binding protein is implicated in cancer cell proliferation, invasion and tumour angiogenesis. Several Gal1-targeting compounds have recently emerged. OTX008 is a calixarene derivative designed to bind the Gal1 amphipathic β-sheet conformation. Our study contributes to the current understanding of the role of Gal1 in cancer progression, providing mechanistic insights into the anti-tumoural activity of a novel small molecule Gal1-inhibitor.

METHODS

We evaluated in vitro OTX008 effects in a panel of human cancer cell lines. For in vivo studies, an ovarian xenograft model was employed to analyse the antitumour activity. Finally, combination studies were performed to analyse potential synergistic effects of OTX008.

RESULTS

In cultured cancer cells, OTX008 inhibited proliferation and invasion at micromolar concentrations. Antiproliferative effects correlated with Gal1 expression across a large panel of cell lines. Furthermore, cell lines expressing epithelial differentiation markers were more sensitive than mesenchymal cells to OTX008. In SQ20B and A2780-1A9 cells, OTX008 inhibited Gal1 expression and ERK1/2 and AKT-dependent survival pathways, and induced G2/M cell cycle arrest through CDK1. OTX008 enhanced the antiproliferative effects of Semaphorin-3A (Sema3A) in SQ20B cells and reversed invasion induced by exogenous Gal1. In vivo, OTX008 inhibited growth of A2780-1A9 xenografts. OTX008 treatment was associated with downregulation of Gal1 and Ki67 in treated tumours, as well as decreased microvessel density and VEGFR2 expression. Finally, combination studies showed OTX008 synergy with several cytotoxic and targeted therapies, principally when OTX008 was administered first.

CONCLUSION

This study provides insights into the role of Gal1 in cancer progression as well as OTX008 mechanism of action, and supports its further development as an anticancer agent.

Targeting the Ras-ERK pathway in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PAC) stands as the poorest prognostic tumor of the digestive tract with limited therapeutic options. PAC carcinogenesis is associated with the loss of function of tumor suppressor genes such as INK4A, TP53, BRCA2, and DPC4, and only a few activated oncogenes among which K-RAS mutations are the most prevalent. The K-RAS mutation occurs early in PAC carcinogenesis, driving downstream activation of MEK and ERK1/2 which promote survival, invasion, and migration of cancer cells. In PAC models, inhibition of members of the Ras-ERK pathway blocks cellular proliferation and metastasis development. As oncogenic Ras does not appear to be a suitable drug target, inhibitors targeting downstream kinases including Raf and MEK have been developed and are currently under evaluation in clinical trials. In this review, we describe the role of the Ras-ERK pathway in pancreatic carcinogenesis and as a new therapeutic target for the treatment of PAC.

Stromal expression of SPARC in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) stands as the poorest prognostic tumor of the digestive tract, with a 5-year survival rate of less than 5%. Therapeutic options for unresectable PDAC are extremely limited and there is a pressing need for expanded therapeutic approaches to improve current options available with gemcitabine-based regimens. With PDAC displaying one of the most prominent desmoplastic stromal reactions of all carcinomas, recent research has focused on the microenvironment surrounding PDAC cells. Secreted protein acid and rich in cysteine (SPARC), which is overexpressed in PDAC, may display tumor suppressor functions in several cancers (e.g., in colorectal, ovarian, prostate cancers, and acute myelogenous leukemia) but also appears to be overexpressed in other tumor types (e.g., breast cancer, melanoma, and glioblastoma). The apparent contradictory functions of SPARC may yield inhibition of angiogenesis via inhibition of vascular endothelial growth factor, while promoting epithelial-to-mesenchymal transition and invasion through matrix metalloprotease expression. This feature is of particular interest in PDAC where SPARC overexpression in the stroma stands along with inhibition of angiogenesis and promotion of cancer cell invasion and metastasis. Several therapeutic strategies to deplete stromal tissue have been developed. In this review, we focused on key preclinical and clinical data describing the role of SPARC in PDAC biology, the properties, and mechanisms of delivery of drugs that interact with SPARC and discuss the proof-of-concept clinical trials using nab-paclitaxel.

Abstract A238: c-MET as a target for MET inhibitors in patients with poor prognostic pancreatic adenocarcinoma following completed surgical resection

Context: Pancreatic adenocarcinoma (PAC) displays a prominent desmoplastic stromal reaction, leading to tumor hypoxia and driving a selective pressure that selects cells exhibiting aggressive phenotypes. Activation of the HGF/c-MET pathway is involved in tumor-stroma interactions and promotes PAC cells proliferation, invasion, EMT, and stem cellness. As a background for identifying tumors that could benefit from MET inhibitors, we set a study looking at c-MET expression and hypoxia in PAC.

Patients and Methods: Patients who underwent curative surgical resection for PAC and received no adjuvant chemotherapy (“pure” prognostic value) were selected for this study. c-MET expression was assessed using immunochemistry and graded on a scale from 0 to 4, along with the microenvironment characteristics as defined by HIF-1α and CA9 immunostaining (hypoxia), CD31 expression (microvascular density [MVD]), and stroma abundance. Clinical, pathological, and molecular biomarkers have been correlated with disease-free (DFS) and overall (OS) survivals.

Results: thirty-seven patients have been analyzed in this study. Twenty-seven percent of tumors (10/37) expressed high c-MET (score ≥ 3). High c-MET expression was associated with moderate/poor differentiation (p = 0.017), presence of isolated tumor cells in the stroma (p = 0.023), and low stroma abundance (r = -0.445, p = 0.0074), but not with hypoxia-related markers (HIF-1α, CA9, or MVD). High c-MET expression was associated with shorter DFS (median: 7.7 vs 33.0 months, HR: 2,207, p=0.025) and OS (median: 12.1 vs 38.9 months, HR: 2,207, p=0.0099) than low c-MET expression in PAC. High c-MET expression combined with tumor size and lymph node ratio (defined as the ratio of lymph nodes with tumor metastasis to the total lymph nodes dissected) predicted risk of early local or distant recurrence (RFS < 12 months) with an AUC = 0.836.

Conclusion: c-MET appears to be a strong prognostic marker in completely resected PAC that may help to identify patients at high risk of early recurrence. Although the number of patients entered in this study was limited, this study suggests to explore the anti-metastatic potential of MET inhibitors in high c-MET expressing PAC following complete resection.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A238.

Citation Format: Cindy Neuzillet, Jérôme Cros, Annemilaï Tijeras-Raballand, Julien Moroch, Louis de Mestier, Maryse Baia, Pierre Bedossa, Valérie Paradis, Alain Sauvanet, Jean-Baptiste Bachet, Eric Raymond, Pascal Hammel, Anne Couvelard. c-MET as a target for MET inhibitors in patients with poor prognostic pancreatic adenocarcinoma following completed surgical resection. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A238.

Abstract A228: TGF-beta signaling inhibition using LY2157299 affects proliferation or invasion in hepatocarcinoma cells and patient samples

Background: To date, the only FDA approved targeted agent in advanced hepatocarcinomas is sorafenib, indicating a critical need for innovative therapeutic options. LY2157299, a selective ATP-mimetic inhibitor of TGF-β receptor (TβR)-I activation, is currently under clinical investigation in HCC patients after sorafenib or in patients ineligible for sorafenib. Our study aimed at investigating the effects of LY2157299 in HCC cell lines and patient samples with various AFP expression levels.

Materials and Methods: Antiproliferative effects of LY2157299 were evaluated in a panel of human HCC cells by MTT assay. Baseline and phosphorylated (p-) protein levels were assessed by Western blot analysis and mRNA expressions by qRT-PCR. Invasion assays were done on matrigel and in OptiCell systems. Tumor samples from HCC patients were surgically resected and cut in 300 µm thick slices using a Tissue Slicer. Each slice was randomly exposed to LY2157299 (1µM and 10µM) and sorafenib (5µM) for 48h. At the end of treatment, tumor samples were analyzed by immunohistochemistry (IHC) or immunofluorescence (IF).

Results: LY2157299 was evaluated in HEPG2 and HUH-7 AFP-positive and HEP3B and SK-HEP1 AFP negative cells as well as “in lab-established” SK-HEP1-derived cell lines resistant to the tyrosine kinase inhibitors sorafenib (SK-Sora) and sunitinib (SK-Suni). Exogenous stimulation of all HCC cell lines with TGF-β yielded downstream activation of canonical Smad pathway that was potently inhibited with LY2157299 treatment at micromolar concentrations. In contrast, the non-canonical pathways such as MAPK and Akt/mTOR were not activated by TGF-β in most cell lines with the exception of SK-HEP1 cells where LY2157299 restored the basal level of p-ERK1/2, p-AKT and p-S6 kinase phosphorylation. Low concentrations of LY2157299 displayed antiproliferative effects in HEPG2 and HEP3B cells when stimulated by TGF-β but not in other cell lines. LY2157299 yielded potent anti-migratory and anti-invasive properties in invasive SK-HEP1, SK-Suni and SK-Sora cells. Tumor slices from surgically resected advanced HCC tumor from 5 different patients, were exposed ex vivo to LY2157299 or sorafenib for 48h. This method allows the evaluation of novel anticancer agents in whole tumors containing cancer cells and stromal cells. LY2157299 but not sorafenib decreased 2-5 fold the p-Smad2/3. LY2157299 treatment mainly affected PI3K/AKT rather than MAPK signalling pathway. In contrast, sorafenib treatment reduced both PI3K and MAPK pathway activation. IHC analysis of LY2157299 and sorafenib-exposed samples showed a significant decrease (>3 fold) of the proliferative marker Ki67 and increase of the apoptotic marker caspase-3 (3-5 fold). Interestingly, all molecular effects were independent of AFP expression.

Conclusion: TGF-β/TβR-I inactivation using LY2157299 inhibits TGF-β-dependent cell signaling in HCC cell lines with either anti-proliferative or anti-invasive effects depending on the model. In tumor samples from patients, inhibition of TGF-β signaling was associated with inhibition of proliferation and apoptosis induction regardless AFP level. Our data suggest that LY2157299 may be useful for patients with HCC.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A228.

Citation Format: Marie Serova, Annemilaï Tijeras-Raballand, Celia Dos Santos, Karim A. Benhadji, Valerie Paradis, Eric Raymond, Sandrine Faivre, Armand de Gramont. TGF-beta signaling inhibition using LY2157299 affects proliferation or invasion in hepatocarcinoma cells and patient samples. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A228.

Abstract C20: In vitro effects of Debio 1143, a novel oral IAP inhibitor, in human SCCHN cell lines and tumor specimens

Background: Resistance to radiotherapy and chemotherapy-induced apoptosis is a hallmark of cancer. Inhibitors of apoptosis proteins (IAPs) are negative modulators of apoptosis frequently expressed in various cancers, and, as such, attractive targets to overcome resistance to cancer therapy. The oral SMAC mimetic Debio 1143 (D1143, a.k.a AT-406), an antagonist of multiple IAPs (cIAP1/2 and XIAP), is currently investigated in a Phase I oncology clinical trial. This study aimed at evaluating D1143 activity as a single agent and in combination with TNF-α, TRAIL, cisplatin or carboplatin, in various SCCHN models.

Materials and Methods: The antiproliferative effects of D1143 were evaluated in a panel of 5 human SCCHN cell lines by MTT assay. Baseline and phosphorylated protein levels were detected by Western blot analysis. Tumor samples from SCCHN patients were surgically resected and cut into 300 µm thick slices using a tissue slicer (TIPCAN®). Each slice was exposed to 10 µM D1143 and/or 1 µM of platinum-based drug for 48 hours. Tumor samples were analyzed by immunohistochemistry (IHC) or immunofluorescence to visualize the effects of the treatment on various biomarkers of cell apoptosis, proliferation, and drug target engagement.

Results: A panel of 5 SCCHN cell lines was characterized for the expression of c-IAP1/2, XIAP, Bcl2, LRIG1, and other proteins implicated in resistance to cell death. D1143 alone displayed limited antiproliferative activity in only one cell line (Detroit 562). However, two SCCHN cell lines were sensitive to D1143 and TRAIL combined (SQ20B and SCC15), three were sensitive to D1143 and TNF-α combined (SQ20B, SCC61, and Detroit 562), and one was resistant to both combinations (HEP2). In Detroit 562 sensitive cells, 10 µM D1143 induced sustained cIAP1/2 degradation after 15 minutes of exposure. In contrast, in the HEP2 insensitive cell line, D1143 induced slight and transient inhibition of cIAP1/2. IHC analyses revealed that ex vivo exposure to D1143 of tumor explants freshly resected from SCCHN patients decreased cIAP1 staining. Treatment of tumor samples with D1143 combined with cisplatin or carboplatin augmented the cleavage of caspase 3 compared to controls suggesting induction of apoptosis.

Conclusion: In 4 out of 5 SCCHN cell lines, D1143 induced cIAP1/2 degradation and potentiated TNF-α or TRAIL-induced antiproliferative effects. D1143 combined with carboplatin and cisplatin in SCCHN patient samples induced caspase 3-dependent apoptosis. D1143 in combination with conventional chemotherapies may be considered as a potential treatment for SCCHN patients.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C20.

Citation Format: Marie Serova, Annemilaï Tijeras-Raballand, Sebastien Albert, Sandrine Faivre, Eric Raymond, Anne Vaslin, Claudio Zanna, Gregoire Vuagniaux, Armand de Gramont. In vitro effects of Debio 1143, a novel oral IAP inhibitor, in human SCCHN cell lines and tumor specimens. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C20.

Unraveling galectin-1 as a novel therapeutic target for cancer

Galectins belong to a family of carbohydrate-binding proteins with an affinity for β-galactosides. Galectin-1 is differentially expressed by various normal and pathologic tissues and displays a wide range of biological activities. In oncology, galectin-1 plays a pivotal role in tumor growth and in the multistep process of invasion, angiogenesis, and metastasis. Evidence indicates that galectin-1 exerts a variety of functions at different steps of tumor progression. Moreover, it has been demonstrated that galectin-1 cellular localization and galectin-1 binding partners depend on tumor localization and stage. Recently, galectin-1 overexpression has been extensively documented in several tumor types and/or in the stroma of cancer cells. Its expression is thought to reflect tumor aggressiveness in several tumor types. Galectin-1 has been identified as a promising drug target using synthetic and natural inhibitors. Preclinical data suggest that galectin-1 inhibition may lead to direct antiproliferative effects in cancer cells as well as antiangiogenic effects in tumors. We provide an up-to-date overview of available data on the role of galectin-1 in different molecular and biochemical pathways involved in human malignancies. One of the major challenges faced in targeting galectin-1 is the translation of current knowledge into the design and development of effective galectin-1 inhibitors in cancer therapy.

Benchmarking effects of mTOR, PI3K, and dual PI3K/mTOR inhibitors in hepatocellular and renal cell carcinoma models developing resistance to sunitinib and sorafenib

PURPOSE

To evaluate first-generation rapamycin analogs (everolimus, temsirolimus, and rapamycin) and second-generation drugs inhibiting mTOR kinase (AZD-8055), PI3K (BKM-120) or both (BEZ-235 and GDC-0980) in hepatocellular carcinoma (HCC) and renal cell carcinoma (RCC) cells characterized for acquired resistance to sorafenib or sunitinib.

METHODS

Anti-proliferative (MTT assay) and cell signaling (Western blot) effects of rapamycin analogs (1-20 μM) and second-generation drugs (0.03-20.0 μM) were assessed in human HCC SK-HEP1, RCC 786-0, and sorafenib- (SK-Sora) or sunitinib-resistant (786-Suni) cells.

RESULTS

In SK-HEP1 cells displaying high PTEN and Bcl2 expression, rapamycin analogs had poor anti-proliferative effects. However, SK-Sora cells were more sensitive to rapamycin analogs (≥1 μM) than SK-HEP1 cells. In 786-0 cells, lacking PTEN and Bcl2 expression, ≥1 μM rapamycin analogs blocked mTORC1 signaling, transiently activated Akt, and inhibited cell proliferation. Protracted sunitinib exposure in 786-Suni cells yielded an increase in p27 expression and a decreased sensitivity to rapamycin analogs, although mTORC1 function could be inhibited with rapamycin analogs. Second-generation drugs induced more potent growth inhibition than rapamycin analogs at concentrations >0.03 μM in parental cells, SK-Sora, and 786-Suni cells. Growth inhibitory concentrations of these new drugs also blocked mTORC1 downstream targets.

CONCLUSIONS

Rapamycin analogs inhibited mTORC1 downstream targets and yielded anti-proliferative effects in HCC and RCC cells. Second-generation drugs also appeared to be potent inhibitors of mTORC1 signaling; however, they appeared to be far more potent in inhibiting cellular proliferation in parental HCC and RCC cells and in cells developing resistance to sorafenib or sunitinib.

Prognostic value of the chemokine receptor CXCR4 and epithelial-to-mesenchymal transition in patients with squamous cell carcinoma of the mobile tongue

OBJECTIVE

The aim of this study was to evaluate the expression and the prognostic value of chemokine receptor 4 (CXCR4), its cognate ligand the CXCL12, and markers of epithelial-to-mesenchymal transition (EMT) in squamous cell carcinoma (SCC) of the mobile tongue.

PATIENTS AND METHODS

Patients with primary SCC of the mobile tongue who underwent surgery in our center were screened retrospectively. Patients without prior treatment, who had pre-surgery TNM staging and available tumor samples, were eligible. Protein expression of CXCL12, CXCR4, CA9, E-cadherin, and vimentin was determined by immunohistochemical staining, scored, and correlated with clinical and pathological parameters and overall survival. Multivariate and Cox proportional hazards analyses were performed.

RESULTS

Among 160 patients treated and screened, 47 were analyzed. CXCR4 and CXCL12 expression was high in tumor cells. CXCR4 expression in primary tumor samples was significantly higher in patients with high-grade tumors, lymph node metastases, and microscopic nerve invasion (p ≤ 0.05). There was a non-significant trend towards a correlation between high CXCL12 expression and pathologic tumor stage (p=0.07). Tumors with high CXCR4 expression correlated with poor overall survival (hazard ratio=3.6, 95% confidence interval 1.3-9.7; p=0.011), notably in the CXCR4(high)/vimentin-positive subgroup. Vimentin-positive tumors, characterizing EMT, were associated with lower survival (hazard ratio=4.5, 95% confidence interval 1.6-12.3; p=0.0086). Multivariate analysis confirmed vimentin (but not CXCR4) expression as an independent prognostic factor of poor overall survival (p=0.016).

CONCLUSION

Our results suggest that CXCR4 is a marker of tumor aggressiveness and vimentin is an important and independent prognostic factor in patients with SCC of the mobile tongue.

Netrin-4 delays colorectal cancer carcinomatosis by inhibiting tumor angiogenesis

A close relationship between tumor angiogenesis, growth, and carcinomatosis has been observed. Netrin-4 (NT-4) has been shown to regulate angiogenic responses. We aimed to examine the effects of NT-4 on colon tumor angiogenesis, growth, and carcinomatosis. We showed that NT-4 was expressed in human colon cancer cells (LS174). A 20-fold increase in NT-4 expression was stably induced by NT-4 pcDNA in LS174 cells. In vivo, a Matrigel angiogenesis assay showed that NT-4 overexpression altered vascular endothelial growth factor (VEGF)/basic fibroblast growth factor-induced angiogenesis. In nude mice with LS174 xenografts, NT-4 overexpression inhibited tumor angiogenesis and growth. In addition, these NT-4-involved inhibitory effects were associated with decreased tumor cell proliferation and increased tumor cell apoptosis. Using an orthotopic peritoneal carcinomatosis model, we demonstrated that NT-4 overexpression decreased colorectal cancer carcinomatosis. Moreover, carcinomatosis-related ascites formation was significantly decreased in mice transplanted with NT-4 LS174 cells versus control LS174 cells. The antiangiogenic activity of NT-4 was probably mediated by binding to its receptor neogenin. Netrin-4 had a direct effect on neither in vitro apoptosis and proliferation of cultured LS174 cells nor the VEGF-induced acute increase in vascular permeability in vivo. We propose that NT-4 overexpression decreases tumor growth and carcinomatosis, probably via an antiangiogenic effect, underlying the potential therapeutic interest in NT-4 in the treatment of colorectal cancer growth and carcinomatosis.