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Only a minority of patients derive long-term clinical benefit from anti-programmed cell death protein 1 (anti-PD-1) or anti-programmed death-ligand 1 (anti-PD-L1) monoclonal antibodies. The presence of tertiary lymphoid structures (TLSs) has been associated with improved survival in several tumor types. Here, using a large-scale retrospective analysis of three independent cohorts of patients with cancer who were treated with anti-PD-1 or anti-PD-L1 antibodies, we show that the presence of mature TLSs was associated with improved objective response rates, progression-free survival and overall survival, independent of PD-L1 expression status and CD8+ T cell density. These results pave the way for using TLS detection to select patients who are more likely to benefit from immune checkpoint blockade. Italiano and colleagues demonstrate the utility of mature tertiary lymphoid structures to predict response to immunotherapy, with pathologic analysis in three independent patient cohorts spanning multiple tumor types.

Sarcomas are heterogeneous malignant mesenchymal neoplasms with limited sensitivity to immunotherapy. We recently demonstrated an increase in Kynurenine Pathway (KP) activity in the plasma of sarcoma patients treated with pembrolizumab. While the KP has already been described to favor immune escape through the degradation of L-Tryptophan and production of metabolites including L-Kynurenine, Indoleamine 2,3 dioxygenase (IDO1), a first rate-limiting enzyme of the KP, still represents an attractive therapeutic target, and its blockade had not yet been investigated in sarcomas. Using immunohistochemistry, IDO1 and CD8, expression profiles were addressed within 203 cases of human sarcomas. At a preclinical level, we investigated the modulation of the KP upon PDL1 blockade in a syngeneic model of sarcoma through mRNA quantification of key KP enzymes within the tumor. Furthermore, in order to evaluate the possible anti-tumor effect of IDO blockade in combination with PDL1 blockade, an innovative IDO inhibitor (GDC-0919) was used. Its effect was first assessed on Kynurenine to Tryptophan ratio at plasmatic level and also within the tumor. Following GDC-0919 treatment, alone or in combination with anti-PDL1 antibody, tumor growth, immune cell infiltration, and gene expression profiling were measured. IDO1 expression was observed in 39.1% of human sarcoma cases and was significantly higher in tumors with high CD8 infiltration. In the pre-clinical setting, blockade of PDL1 led to a strong anti-tumor effect and was associated with an intratumoral inflammatory cytokines signature driven by Ifng but also with a modulation of the KP enzymes including Ido1 and Ido2. IDO1 inhibition using GDC-0919 resulted in (i) a significant decrease of plasmatic Kynurenine to Tryptophan ratio and in (ii) a decrease of tumoral Kynurenine. However, GDC-0919 used alone or combined with anti-PDL1, did not show anti-tumoral activity and did not affect the tumor immune cell infiltrate. In order to elucidate the mechanism(s) underlying the lack of effect of GDC-0919, we analyzed the gene expression profile of intratumoral biopsies. Interestingly, we have found that GDC-0919 induced a downregulation of the expression of pvr and granzymes, and an upregulation of inhba and Dtx4 suggesting a potential role of the IDO pathway in the control of NK function.

Anne Rodallec,1 Guillaume Sicard,1 Sarah Giacometti,1 Manon Carré,1 Bertrand Pourroy,2 Fanny Bouquet,3 Ariel Savina,3 Bruno Lacarelle,1 Joseph Ciccolini,1 Raphaelle Fanciullino1 1SMARTc Unit, Laboratory of Pharmacokinetics and Toxicology UFR Pharmacy, Center for Research on Cancer of Marseille, Inserm UMR1068, CNRS UMR7258, Aix Marseille University, Marseille, France; 2Pharmacy Department, APHM La Conception, Marseille, France; 3Roche Institute, Boulogne Billancourt, France Purpose: Nanoparticles are of rising interest in cancer research, but in vitro canonical cell monolayer models are not suitable to evaluate their efficacy when prototyping candidates. Here, we developed three-dimensional (3D) spheroid models to test the efficacy of trastuzumab-docetaxel immunoliposomes in breast cancer prior to further testing them in vivo. Materials and methods: Immunoliposomes were synthesized using the standard thin film method and maleimide linker. Two human breast cancer cell lines varying in Her2 expression were tested: Her2+ cells derived from metastatic site: mammary breast MDA-MB-453 and triple-negative MDA-MB-231 cells. 3D spheroids were developed and tested with fluorescence detection to evaluate viability. In vivo efficacy and biodistribution studies were performed on xenograft bearing nude mice using fluorescent and bioluminescent imaging. Results: In vitro, antiproliferative efficacy was dependent upon cell type, size of the spheroids, and treatment scheduling, resulting in subsequent changes between tested conditions and invivo results. Immunoliposomes performed better than free docetaxel + free trastuzumab and ado-trastuzumab emtansine (T-DM1). On MDA-MB-453 and MDA-MB-231 cell growth was reduced by 76% and 25%, when compared to free docetaxel + free trastuzumab and by 85% and 70% when compared to T-DM1, respectively. In vivo studies showed tumor accumulation ranging from 3% up to 15% of the total administered dose in MDA-MB-453 and MDA-MB-231 bearing mice. When compared to free docetaxel + free trastuzumab, tumor growth was reduced by 89% (MDA-MB-453) and 25% (MDA-MB-231) and reduced by 66% (MDA-MB-453) and 29% (MDA-MB-231) when compared to T-DM1, an observation in line with data collected from 3D spheroids experiments. Conclusion: We demonstrated the predictivity of 3D in vitro models when developing and testing nanoparticles in experimental oncology. In vitro and in vivo data showed efficient drug delivery with higher efficacy and prolonged survival with immunoliposomes when compared to current anti-Her2 breast cancer strategies. Keywords: docetaxel, trastuzumab, breast cancer, immunoliposome, spheroids, distribution, tumor xenograftErratumfor this paper has been published

Background Trastuzumab plus docetaxel is a mainstay to treat HER2-positive breast cancers. However, developing nanoparticles could help to improve the efficacy/toxicity balance of this doublet by improving drug trafficking and delivery to tumors. This project aimed to develop an immunoliposome in breast cancer, combining docetaxel encapsulated in a stealth liposome engrafted with trastuzumab, and comparing its performances on human breast cancer cell lines with standard combination of docetaxel plus trastuzumab. Methods Several strategies to engraft trastuzumab to pegylated liposomes were tested. Immunoliposomes made of natural (antibody nanoconjugate-1 [ANC-1]) and synthetic lipids (ANC-2) were synthesized using standard thin film method and compared in size, morphology, docetaxel encapsulation, trastuzumab engraftment rates and stability. Antiproliferative activity was tested on human breast cancer models ranging from almost negative (MDA-MB-231), positive (MDA-MB-453) to overexpressing (SKBR3) HER2. Finally, cell uptake of ANC-1 was studied by electronic microscopy. Results ANC-1 showed a greater docetaxel encapsulation rate (73%±6% vs 53%±4%) and longer stability (up to 1 week) as compared with ANC-2. Both ANC presented particle size ≤150 nm and showed similar or higher in vitro antiproliferative activities than standard treatment, ANC-1 performing better than ANC-2. The IC50s for docetaxel combined to free trastuzumab were 8.7±4, 2±0.7 and 6±2 nM with MDA-MB-231, MDA-MB-453 and SKBR3, respectively. The IC50s for ANC-1 were 2.5±1, 1.8±0.6 and 3.4±0.8 nM and for ANC-2 were 1.8±0.3 nM, 2.8±0.8 nM and 6.8±1.8 nM with MDA-MB-231, MDA-MB-453 and SKBR3, respectively. Cellular uptake appeared to depend on HER2 expression, the higher the expression, the higher the uptake. Conclusion In vitro results suggest that higher antiproliferative efficacy and efficient drug delivery can be achieved in breast cancer models using nanoparticles., Video abstract

Purpose: There is extensive cross-talk between VEGF- and EGFR-pathway signaling in colorectal cancer. However, combinations of VEGF- and EGFR-targeted monoclonal antibodies (mAb) show disappointing activity, in particular for patients with mutant RAS. Previous results show that tyrosine kinase inhibitors (TKI) can be active in colorectal cancer models resistant to mAbs. This prompted us to examine whether the activity of bevacizumab can be increased by combination with erlotinib. Experimental Design: The antitumor activity of bevacizumab, erlotinib, and their combination was determined in colorectal cancer models with different RAS status and bevacizumab sensitivity. EGFR/VEGF pathway activation was characterized by immunohistochemistry, Western blot, and ELISA assays. The influence of cetuximab and erlotinib on EGF-mediated migration and the EGFR–EGF ligand feedback loop was established in colorectal cancer cell lines with different RAS status. Results: The addition of erlotinib increased bevacizumab activity in all models independent of RAS status. Bevacizumab exposure was accompanied by marked EGFR activation in tumor cells as well as in tumor-associated endothelial cells (TECs) and resulted in strong accumulation of intracellular EGFR, which could be attenuated by erlotinib. In cellular models, erlotinib was able to attenuate EGF-mediated functions in all cell lines independent of RAS status while cetuximab only showed activity in RAS wild-type cells. Conclusions: These results should provide a molecular framework to better understand the increased activity of the bevacizumab–erlotinib combination, compared with bevacizumab alone, in the GERCOR DREAM phase III clinical trial. Differential activity of mAbs and TKIs targeting the same signaling pathway is likely applicable for other tumor types. Clin Cancer Res; 24(11); 2548–58. ©2018 AACR.

The benefit of EGFR–TKI in non–small cell lung cancer has been demonstrated in mutant EGFR tumors as first-line treatment but the benefit in wild-type EGFR tumors is marginal as well as restricted to maintenance therapy in pretreated patients. This work aimed at questioning the effects of cisplatin initial treatment on the EGFR pathway in non–small cell lung cancer and the functional consequences in vitro and in in vivo animal models of patient-derived xenografts (PDX). We establish here that cisplatin pretreatment specifically sensitizes wild-type EGFR-expressing cells to erlotinib, contrary to what happens in mutant EGFR cells and with a blocking EGFR antibody, both in vitro and in vivo. The sensitization entails the activation of the kinase Src upstream of EGFR, thereafter transactivating EGFR through a ligand-independent activation. We propose a combination of markers that enable to discriminate between the tumors sensitized to erlotinib or not in PDX models, which should be worth testing in patients. These markers might be useful for the selection of patients who would benefit from erlotinib as a maintenance therapy. Mol Cancer Ther; 16(8); 1634–44. ©2017 AACR.

Over 60% of human melanoma tumors bear a mutation in the BRAF gene. The most frequent mutation is a substitution at codon 600 (V600E), leading to a constitutively active BRAF and overactivation of the MAPK pathway. Patients harboring mutated BRAF respond to kinase inhibitors such as vemurafenib. However, these responses are transient, and relapses are frequent. Melanoma cells are efficiently lysed by activated natural killer (NK) cells. Melanoma cells express several stress-induced ligands that are recognized by activating NK-cell receptors. We have investigated the effect of vemurafenib on the immunogenicity of seven BRAF-mutated melanoma cells to NK cells and on their growth and sensitivity to NK-cell–mediated lysis. We showed that vemurafenib treatment modulated expression of ligands for two activating NK receptors, increasing expression of B7-H6, a ligand for NKp30, and decreasing expression of MICA and ULBP2, ligands for NKG2D. Vemurafenib also increased expression of HLA class I and HLA-E molecules, likely leading to higher engagement of inhibitory receptors (KIRs and NKG2A, respectively), and decreased lysis of vemurafenib-treated melanoma cell lines by cytokine-activated NK cells. Finally, we showed that whereas batimastat (a broad-spectrum matrix metalloprotease inhibitor) increased cell surface ULBP2 by reducing its shedding, vemurafenib lowered soluble ULBP2, indicating that BRAF signal inhibition diminished expression of both cell-surface and soluble forms of NKG2D ligands. Vemurafenib, inhibiting BRAF signaling, shifted the balance of activatory and inhibitory NK ligands on melanoma cells and displayed immunoregulatory effects on NK-cell functional activities. Cancer Immunol Res; 5(7); 582–93. ©2017 AACR.

Nanoparticles have been used for decades in breast cancer. More recently, anti-human epidermal receptor 2 (Her2) immunoliposomes are of rising interest. However, recent studies have questioned the actual relevance of using anti-Her2 antibodies to improve liposome distribution and efficacy. Using standard thin-film method and maleimide linker, we have synthesized a 140-nm docetaxel-trastuzumab immunoliposome. This nanoparticle was then tested on a canonical Her2-overexpressing breast cancer model (i.e., SKBR3), using 3D spheroids and xenografted mice. Its efficacy was compared with free docetaxel + trastuzumab, liposomal docetaxel + free trastuzumab and to reference antibody-drug conjugate trastuzumab-emtansine (T-DM1). Immunoliposomes resulted in better efficacy as compared with all other treatments, both in vitro and in vivo. To explain such an improvement, immunoliposome biodistribution was investigated using live imaging in xenografted mice. Surprisingly, no difference in tumor uptake was found between anti-Her2 immunoliposomes and standard docetaxel liposomes (i.e., 1.9 ± 1.2 vs. 1.7 ± 0.5% at the end of treatment and 1.4 ± 0.6 vs. 1.6 ± 0.4% at the end of the study, respectively, P > 0.05). We hypothesized that passive targeting (i.e., enhanced permeation and retention effect) contributed more to tumor distribution than active targeting and that the observed differences in efficacy could come from a better internalization of immunoliposomes into Her2+ cells as compared with standard liposomes, and not from a higher specificity towards tumor tissue.

Although lung cancer patients harboring EGFR mutations benefit from treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKI), most of them rapidly relapse. RHOB GTPase is a critical player in both lung carcinogenesis and the EGFR signaling pathway; therefore, we hypothesized that it could play a role in the response to EGFR-TKI. In a series of samples from EGFR-mutated patients, we found that low RHOB expression correlated with a good response to EGFR-TKI treatment while a poor response correlated with high RHOB expression (15.3 versus 5.6 months of progression-free survival). Moreover, a better response to EGFR-TKI was associated with low RHOB levels in a panel of lung tumor cell lines and in a lung-specific tetracycline-inducible EGFR L858R transgenic mouse model. High RHOB expression was also found to prevent erlotinib-induced AKT inhibition in vitro and in vivo. Furthermore, a combination of the new-generation AKT inhibitor G594 with erlotinib induced tumor cell death in vitro and tumor regression in vivo in RHOB-positive cells. Our results support a role for RHOB/ AKT signaling in the resistance to EGFR-TKI and propose RHOB as a potential predictor of patient response to EGFR-TKI treatment.

International audience; Follicular lymphoma (FL) is a common non Hodgkin's lymphoma subtype in which immune escape mechanisms are implicated in resistance to chemo-immunotherapy. Although molecular studies point to qualitative and quantitative deregulation of immune checkpoints, in depth cellular analysis of FL immune escape is lacking. Here, by functional assays and in silico analyses we show that a subset of FL patients displays a 'high' immune escape phenotype. These FL cases are characterized by abundant infiltration of PD1+ CD16+ TCRVγ9Vδ2 γδ T lymphocytes. In a 3D co-culture assay (MALC), γδ T cells mediate both direct and indirect (ADCC in the presence of anti-CD20 mAbs) cytolytic activity against FL cell aggregates. Importantly, PD-1, which is expressed by most FL-infiltrating γδ T lymphocytes with ADCC capacity, impairs these functions. In conclusion, we identify a PD1-regulated γδ T cell cytolytic immune component in FL. Our data provide a treatment rational by PD-1 blockade aimed at boosting γδ T cell anti-tumor functions in FL.

Background Inhibition of ChK1 appears as a promising strategy for selectively potentiate the efficacy of chemotherapeutic agents in G1 checkpoint-defective tumor cells such as those that lack functional p53 protein. The p53 pathway is commonly dysregulated in soft-tissue sarcomas (STS) through mutations affecting TP53 or MDM2 amplification. GDC-0575 is a selective ATP-competitive inhibitor of CHK1. Methods We have performed a systematic screening of a panel of 10 STS cell lines by combining the treatment of GDC-0575 with chemotherapy. Cell proliferation, cell death and cell cycle analysis were evaluated with high throughput assay. In vivo experiments were carried out by using TP53-mutated and TP53 wild-type patient-derived xenograft models of STS. Clinical activity of GDC-0575 combined with chemotherapy in patients with TP53-mutated and TP53 wild-type STS was also assessed. Results We found that GDC-0575 abrogated DNA damage-induced S and G2–M checkpoints, exacerbated DNA double-strand breaks and induced apoptosis in STS cells. Moreover, we observed a synergistic or additive effect of GDC-0575 together with gemcitabine in vitro and in vivo in TP53-proficient but not TP53-deficient sarcoma models. In a phase I study of GDC-0575 in combination with gemcitabine, two patients with metastatic TP53-mutated STS had an exceptional, long-lasting response despite administration of a very low dose of gemcitabine whereas one patient with wild-type TP53 STS had no clinical benefit. Genetic profiling of samples from a patient displaying secondary resistance after 1 year showed loss of one preexisting loss-of-function mutation in the helical domain of DNA2. Conclusion We provide the first preclinical and clinical evidence that potentiation of chemotherapy activity with a CHK1 inhibitor is a promising strategy in TP53-deficient STS and deserves further investigation in the phase II setting.

Loyher et al. demonstrate that lung tumors are densely colonized by macrophages of various ontogenies. These distinct developmental origins dictate tumor-associated macrophages relative anatomical distributions, functions and responses to anti-cancer therapies., Tissue-resident macrophages can self-maintain without contribution of adult hematopoiesis. Herein we show that tissue-resident interstitial macrophages (Res-TAMs) in mouse lungs contribute to the pool of tumor-associated macrophages (TAMs) together with CCR2-dependent recruited macrophages (MoD-TAMs). Res-TAMs largely correlated with tumor cell growth in vivo, while MoD-TAMs accumulation was associated with enhanced tumor spreading. Both cell subsets were depleted after chemotherapy, but MoD-TAMs rapidly recovered and performed phagocytosis-mediated tumor clearance. Interestingly, anti-VEGF treatment combined with chemotherapy inhibited both Res and Mod-TAM reconstitution without affecting monocyte infiltration and improved its efficacy. Our results reveal that the developmental origin of TAMs dictates their relative distribution, function, and response to cancer therapies in lung tumors., Graphical Abstract

GA101/obinutuzumab is a novel type II anti-CD20 monoclonal antibody (mAb), which is more effective than rituximab (RTX) in preclinical and clinical studies when used in combination with chemotherapy. Ca2+ signaling was shown to play a role in RTX-induced cell death. This report concerns the effect of GA101 on Ca2+ signaling and its involvement in the direct cell death induced by GA101. We reveal that GA101 triggered an intracellular Ca2+ increase by mobilizing intracellular Ca2+ stores and activating Orai1-dependent Ca2+ influx in non-Hodgkin lymphoma cell lines and primary B-Cell Chronic Lymphocytic Leukemia (B-CLL) cells. According to the cell type, Ca2+ was mobilized from two distinct intracellular compartments. In Raji, BL2, and B-CLL cells, GA101 induced a Ca2+ release from lysosomes, leading to the subsequent lysosomal membrane permeabilization and cell death. Inhibition of this calcium signaling reduced GA101-induced cell death in these cells. In SU-DHL-4 cells, GA101 mobilized Ca2+ from the endoplasmic reticulum (ER). Inhibition of ER replenishment, by blocking Orai1-dependent Ca2+ influx, led to an ER stress and unfolded protein response (UPR) which sensitized these cells to GA101-induced cell death. These results revealed the central role of Ca2+ signaling in GA101&rsquo, s action mechanism, which may contribute to designing new rational drug combinations improving its clinical efficacy.

Vemurafenib/PLX4032, a selective inhibitor of mutant BRAFV600E, constitutes a paradigm shift in melanoma therapy. Unfortunately, acquired resistance, which unavoidably occurs, represents one major limitation to clinical responses. Recent studies have highlighted that vemurafenib activated oxidative metabolism in BRAFV600E melanomas expressing PGC1α. However, the oxidative state of melanoma resistant to BRAF inhibitors is unknown. We established representative in vitro and in vivo models of human melanoma resistant to vemurafenib including primary specimens derived from melanoma patients. Firstly, our study reveals that vemurafenib increased mitochondrial respiration and ROS production in BRAFV600E melanoma cell lines regardless the expression of PGC1α. Secondly, melanoma cells that have acquired resistance to vemurafenib displayed intrinsically high rates of mitochondrial respiration associated with elevated mitochondrial oxidative stress irrespective of the presence of vemurafenib. Thirdly, the elevated ROS level rendered vemurafenib-resistant melanoma cells prone to cell death induced by pro-oxidants including the clinical trial drug, elesclomol. Based on these observations, we propose that the mitochondrial oxidative signature of resistant melanoma constitutes a novel opportunity to overcome resistance to BRAF inhibition.

Follicular lymphoma (FL) is a common non Hodgkin's lymphoma subtype in which immune escape mechanisms are implicated in resistance to chemo-immunotherapy. Although molecular studies point to qualitative and quantitative deregulation of immune checkpoints, in depth cellular analysis of FL immune escape is lacking. Here, by functional assays and in silico analyses we show that a subset of FL patients displays a 'high' immune escape phenotype. These FL cases are characterized by abundant infiltration of PD1+ CD16+ TCRVgamma9Vdelta2 gamma delta T lymphocytes and high expression of gamma delta cytolytic markers. In a 3D co-culture assay (MALC), gamma delta T cells could mediate both direct and indirect (ADCC in the presence of anti-CD20 mAbs) cytolytic activity against FL cell aggregates. Importantly, PD-1, which is expressed by most FL-infiltrating gamma delta T lymphocytes with ADCC capacity, impaired these functions. In conclusion, we identify a PD1-regulated gamma delta T cell cytolytic immune component in FL. Our data provide a treatment rational by PD-1 blockade aimed at boosting gamma delta anti-tumor function in FL. Disclosures Morin: IMACTIV-3D: Employment. Lagarde:IMACTIV-3D: Employment. Savina:Institut Roche: Employment. Klein:F. Hoffmann-La Roche Ltd.: Employment, Other: stock, Patents & Royalties.

In HER2-positive breast cancer, the Trastuzumab + Docetaxel doublet has a significant efficacy but is hampered by frequent toxicities that could be addressed with nanoparticles. We have developed an Antibody-Nano Conjugate (ANC), combining docetaxel encapsulated in a stealth liposome engrafted with trastuzumab. This entity is expected to improve the efficacy/toxicity balance of this doublet, by improving trafficking and delivery to the tumors. ANCs were synthesized using thin-film method and trastuzumab was grafted via sulfydryl groups on maleimide polyethylene glycol. Two compositions (ANC-1 and ANC-2) were tested and compared (i.e., size, morphology, encapsulation rate, engrafting rate, and stability). Antiproliferative activity was tested on a panel of human breast cancer models ranging fromHER2-negative (MDA-MB-231) to HER2-positive (MDA-MB-453) or -overexpressing (SKBR3), both on 2D and spheroid models. Biodistribution, efficacy and survival were tested in MDAMB-231 and MDA-MB-453 bearing nude mice. ANC-1 presented a greater size (140 ± 3 nm), docetaxel encapsulation rate (73 ± 6 %) and stability as compared with ANC-2. In vitro, both ANCs were found to be more efficient than standard docetaxel + trastuzumab, with a better performance for ANC-1. In vivo, ANC-1 accumulated better in tumors, resulting in a higher reduction in tumor growth (i.e. >+36%) and prolonged survival (i.e. >+33%) as compared with standard treatment. Both in vitro and in vivo results suggest that higher antiproliferative efficacy and efficient drug delivery can be achieved in breast cancer models. Of note, although modest, even Her2- model (i.e., MDA231) was found to benefit from the nanoparticle. Citation Format: Anne Rodallec, Jean Michel Brunel, Stephane Robert, Sarah Giacometti, Ariel Savina, Fanny Bouquet, Bruno Lacarelle, Joseph Ciccolini, Raphaelle Fanciullino. Characterization, in vitro and in vivo efficacy studies of docetaxel trastuzumab stealth immunoliposome in human breast cancer models [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 3709.

e21559Background: Vismodegib , a selective Hh pathway inhibitor that targets Smoothened (SMO) is a major therapeutic breakthrough for locally advanced (la) or metastatic BCC. During treatment some ...

Drug discovery efforts have focused on the tumor microenvironment in recent years. However, few studies have characterized the stroma component in patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMs). In this study, we characterized the stroma in various models of breast cancer tumors in mice. We performed transcriptomic and flow cytometry analyses on murine populations for a series of 25 PDXs and the two most commonly used GEMs (MMTV-PyMT and MMTV-erBb2). We sorted macrophages from five models. We then profiled gene expression in these cells, which were also subjected to flow cytometry for phenotypic characterization. Hematopoietic cell composition, mostly macrophages and granulocytes, differed between tumors. Macrophages had a specific polarization phenotype related to their M1/M2 classification and associated with the expression of genes involved in the recruitment, invasion and metastasis processes. The heterogeneity of the stroma component of the models studied suggests that tumor cells modify their microenvironment to satisfy their needs. Our observations suggest that such models are of relevance for preclinical studies.

International audience; Lymphomas grow as dense aggregates in patients, but whether this spatial organization affects lymphoma cell biology is unknown. We grew follicular lymphoma (FL) cells in vitro as multicellular aggregates of lymphoma cells to investigate this question. Gene expression analysis revealed that 612 genes were differentially expressed when cells grew in multicellular aggregates of lymphoma cells rather than in suspension. These genes correspond to several GO biological processes, such as hypoxia, activation of NF-κB pathway, and negative regulation of cell cycle, a gene signature also found in the transcriptomes from FL biopsies. Pimonidazole staining, HIF-1A accumulation, and VEGFA release confirmed that cells in multicellular aggregates of lymphoma cells actually respond to hypoxia. In adaptation to such conditions, they also displayed an activated NF-κB pathway and a quiescent status far more frequently than in suspension. When cultured in three dimensions, FL cells display resistance to doxorubicin and bendamustine, two drugs largely used in FL therapy, compared to FL cultured in suspension. Finally, multicellular aggregates of lymphoma cells were also found to be less sensitive to purified natural killer cells. To conclude, our study shows that in FL, spatial organization results in dramatic changes in FL biology, including gene expression, proliferation, drug resistance, and immune escape.

Background: Overexpression of Human Epidermal growth factor Receptor 2 (HER2) in cancer was associated with poor outcome and high chances of recurrence before the development of anti-HER2 agents. Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate targeting HER2 based on its antibody component trastuzumab. After internalization of T-DM1/HER2, Lys-MCC-DM1, a tubulin binding agent is released in the cytoplasm. In spite of therapeutic advances, acquired resistance to treatment remains a major obstacle. A better understanding of the mechanisms of resistance to T-DM1 is necessary to improve treatment regimens for HER2-overexpressing cancer patients. We have developed and characterized resistance models to T-DM1 in order to describe underlying resistance mechanisms and develop alternative strategies. Methods: To develop in vitro T-DM1 resistance models, HER2-overexpressing esophageal adenocarcinoma cell line OE-19 was exposed to increasing doses of T-DM1 several months in the absence or presence of cyclosporin A (CsA, an inhibitor of MDR1 transporter). Resistance models were called OE-19 TR (exposed to T-DM1) and OE-19 TCR (exposed to T-DM1 and CsA). To characterize the resistance models, sensitivity to T-DM1 was assessed by MTT assay, Annexin V-PI staining and xCELLigence. Cell cycle distribution was assessed by propidium iodide using flow cytometry. Cross-resistance was studied by MTT assay. Expression of HER2, ABC transporters and tubulin was studied by rt-qPCR, flow cytometry and/or Western Blot. An expression profile of sensitive and resistant cells to T-DM1 was performed using a pan-genomic Illumina cDNA array. Results: After prolonged exposure of OE-19 cells to T-DM1, IC50 value is 18-fold higher in TR cells and 21-fold higher in TCR cells and both models become less sensitive to T-DM1-induced apoptosis. T-DM1 induced G2/M arrest in OE-19 sensitive cells but not in resistant cells. We found that resistant cells become less sensitive to trastuzumab but remain sensitive to other HER2-targeted therapies such as lapatinib, as well as to a variety of chemotherapy agents. Among the resistant cells, a subpopulation with increased expression MDR1 was identified in OE-19 TR and TCR. Concerning the expression of the main targets of T-DM1 (HER2 and tubulin); we found that HER2 expression and total α and β tubulin expression and content remained unchanged. However the isoforms β2 and β3 were overexpressed in both resistant models. A transcriptomic approach of T-DM1 resistant cells showed modification in adhesion junctions and focal adhesions. Conclusion: Prolonged exposure of the OE-19 cell line to T-DM1 resulted in resistance to this immunoconjugate. We are working on describing the resistance mechanisms to T-DM1, which are important to understand cancer progression in patients receiving this therapy. In the long term, we hope this study will allow proposing agents that benefit T-DM1-refractory cancer patients. Citation Format: Juliette Sauveur, Abdelkamel Chettab, Eva matera, Aurore Cleret, Ariel Savina, Charles Dumontet. Mechanisms of resistance to trastuzumab emtansine in gastric cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 309.

Follicular lymphoma (FL) is the second most common type of B non-Hodgkin’s lymphomas (NHL) and makes up to 40% of all adult lymphomas. Like most carcinomas, NHL grow as spherical tumors. Based on carcinoma 3D models (often described as spheroids) it is acknowledged that spatial organization may profoundly affect tumor cell behavior since important functions are dictated by the collective properties of a cell population rather than those of a single cell. These include growth, metastasis, cell-to-matrix and cell-to-cell interaction, as well as intracellular signaling and resistance to anti-tumor agents or even immune escape. Spatial organization can exert these effects in cancer cells by affecting gene expression profiles or influencing major signaling pathways such as those driven by MAPK, Akt and oncogenic products such as HER-2. More importantly, spatial organization is known to influence the response to antibodies such as Trastuzumab or Pertuzumab. Conventional 2D NHL cell culture models do not reflect the true effects of antibodies as they occur in vivo and may be of limited use. Thus, we recently created a NHL 3D culture system, the so-called Multicellular Aggregates of Lymphoma Cells (MALC) model, using a modification of the “hanging drop” method. This model, which displays similar transcriptomic profiles compared to biopsies from FL patients, is not only useful for studying FL biology, but also for evaluating tumor sensitivity to antibodies since diffusion/distribution is different within a solid 3D tumor. Thus, we recently showed that 3D organization influences direct response to Rituximab (RTX) and GA101 (Obinutuzumab), two monoclonal anti-CD20 antibodies, as we observed a more potent efficiency in MALC model compared to conventional 2D cell culture in term of cell death induction (apoptosis, senescence, lysosomal cell death) and intracellular signaling targeting. Here, we evaluate antibody-dependent cell cytotoxicity in MALC in presence of immune effectors cells such as NK cells and Tgd lymphocytes. We showed that RTX and GA101 induce immune cells activation as attested by CD69 and IFNg increase and immune cells cytotoxic activity as attested by CD107 increase as well as granzyme B and perforine decrease, reflecting granules release. GA101 appears to be more efficient than RTX in effectors cells activation. We correlate this phenomenon with a more potent effect on target cells as attested by MALC volume decrease and cell death induction observed by flow cytometry and confocal microscopy. By investigating intracellular signaling pathways induced during ADCC on both effector (NK) and target cells (MALC), we observed on NK cells the activation of CD16 downstream signaling molecules such as Syk, PLCg2 and Akt, with a more potent effect in presence of GA101 compared to RTX for proximal proteins activation. On the other hand, we showed that RTX and GA101 induced inhibition of classical overactivated signaling pathways such as Syk, Akt, ERK and p38 on target cells. Finally, we asked the question of the presence of immune cells in lymph node isolated from FL patients. By flow cytometry, we were able to determine the percent of NK and gdT cells and present evidences that immune cells number is higher in FL lymph node compared to normal tonsil. Altogether, this study completes our previous works on the identification of MAbs mechanisms of action in a relevant 3D FL model.A better understanding of these mechanisms is necessary to improve therapy by identifying mechanisms of resistance and new therapeutic targets. Moreover, we believe that MALC is a powerful and relevant model for further investigation on FL biology, and also useful for the development/screening of new genotoxic drugs and therapeutic monoclonal antibodies in lymphoma. Disclosures Bezombes: Roche: Research Funding. Savina:roche: Employment. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

Aim: We have recently shown that EGFR- and VEGF(R)- targeted small molecules showed synergistic activity in colorectal cancer (CRC) models refractory to combinations of monoclonal antibodies independent of KRAS status. We here wished to determine the activity of bevacizumab in combination with erlotinib and to elucidate the molecular basis for the activity of the combination. Methods: Three human CRC xenograft models, SW48 (KRAS wt, bevacizumab sensitive), HT-29 (KRAS wt, bevacizumab resistant) and SW620 (KRAS mutant, bevacizumab sensitive) were established in nude mice. Animals were treated with bevacizumab and erlotinib, alone and in combination, and the influence on tumor growth, and the presence of activated EGFR was determined. The influence of erlotinib on the viability of CRC cells and EGFR ligand expression was established under normoxia, hypoxia and hypoxia/reoxygenation. Results: Combinations of bevacizumab and erlotinib were significantly more active than bevacizumab alone for all three xenograft models. Quantitative IHC analysis showed that bevacizumab activated EGFR in the tumor cells as well as in the tumor-associated endothelial cells which was attenuated by erlotinib. Erlotinib was more cytotoxic toward CRC cells under hypoxia and hypoxia/reoxygenation than under normoxia and was able to down-regulate the EGFR ligands TGF-alpha and amphiregulin under all experimental conditions. Conclusions: We here show that combinations of bevacizumab and erlotinib are significantly more active than bevacizumab alone in CRC models with different KRAS status and bevacizumab sensitivity. These findings provided the rational basis for the positive GERCOR phase III DREAM trial. Disclosure: A.K. Larsen: This research was financed in part by Roche; A. Savina: Employed by Roche; B. Chibaudel: Associated with the related DREAM clinical study sponsored by Roche; C. Tournigand: Associated with the related DREAM clinical study sponsored by Roche; T. Andre: Associated with the related DREAM clinical study sponsored by Roche; A. De Gramont: Associated with the related DREAM clinical study sponsored by Roche. All other authors have declared no conflicts of interest.

449 Background: Combinations of EGFR and VEGF(R)-targeted agents have consistently shown at least additive activity in preclinical CRC models when the targeted agents were administered alone (Larsen et al., Pharmacol Therap. 131:80, 2011; Poindessous et al., Clin Cancer Res. 17:6522, 2011) paving the way for the GERCOR DREAM-OPTIMOX3 phase III trial in metastatic CRC. Although use of EGFR-directed mAbs are counter-indicated in CRC patients with mutant KRAS, the situation is less clear for EGFR-targeted TKIs like erlotinib. Methods: Three human CRC xenograft models expressing wt KRAS/BRAF, mutant KRAS or mutant BRAF were established in nude mice. Animals were treated with bevacizumab and erlotinib, alone or in combination, and the influence on tumor growth, viability and the presence of phosphorylated ErbB/HER family members was determined. Treatment-related toxicity was estimated by weight loss. Results: Combinations of bevacizumab and erlotinib were significantly more active than either agent alone for all three xenograft models although the advantage of combining the two agents was particularly striking for the KRAS/BRAF wt xenograft model. Unexpectedly, erlotinib alone showed strong antitumor activity in the BRAF mutant HT-29 xenograft model. The bevacizumab plus erlotinib combination was less toxic, as determined by weight loss, compared to erlotinib alone. Interestingly, IHC analysis showed that bevacizumab activates EGFR in all three xenograft models. Conclusions: We here report that bevacizumab and erlotinib combinations are significantly more active than either agent alone in CRC models with different KRAS and BRAF status. We further demonstrate that bevacizumab activates EGFR signaling similar to what has been described for irinotecan and ionizing radiation. Taken together, our findings suggest that mutant KRAS and BRAF have lesser influence on the sensitivity to EGFR-targeted TKIs than is the case for the EGFR directed mAbs and provide a mechanistic basis for the increased activity of the bevacizumab and erlotinib combination.

Follicular lymphoma (FL) is the second most common type of B non-Hodgkin’s lymphomas (NHL) and makes up 40% of all adult lymphomas. Like most carcinomas, NHL grow as spherical tumors. Based on carcinoma 3D models (often described as spheroids) it is acknowledged that spatial organization may profoundly affect tumor cell behavior since important functions are dictated by the collective properties of a cell population rather than those of a single cell. These include growth, metastasis, cell-to-matrix and cell-to-cell interaction, as well as intracellular signaling and resistance to anti-tumor agents or even immune escape. Spatial organization can exert these effects in cancer cells by affecting gene expression profiles or influencing major signaling pathways such as those driven by MAPK, Akt and oncogenic products such as HER-2. More importantly, spatial organization is known to influence the response to antibodies such as Trastuzumab or Pertuzumab. Conventional 2D NHL cell culture models do not reflect the true effects of antibodies as they occur in vivo and may be of limited use. Thus, we recently created a NHL 3D culture system, the so-called Multicellular Aggregates of Lymphoma Cells (MALC) model, using a modification of the “hanging drop” method. This model is not only useful for studying FL biology, but also for evaluating tumor sensitivity to antibodies since diffusion/distribution is different within a solid 3D tumor. In this study, we present transcriptomic and extracellular matrix proteins expression profiles in 2D, 3D FL cell cultures and patients biopsies, and observed that MALC, but not 2D cultures, display similarities to patients samples. Indeed, we observe an upregulation of genes involved in the response to hypoxia, activation of NFκB pathway and negative regulation of cell cycle promoting the emergence of chemoresistant quiescent cells. Moreover, MALC, in contrast to 2D cultures but as observed in biopsies, exhibit higher expression of fibronectin, laminin, vitronectin and collagen. Recently, we showed that spatial organization also influence response to anti-CD20 monoclonal antibodies such as Rituximab and Obinutuzumab. Here, we investigate the antibody-dependant cell cytotoxicity induced by these two monoclonal anti-CD20 antibodies in the MALC model: cell cytotoxicity, effector and target cells signaling, and spatial localization are presented. Thus, we present an invaluable model for further investigation of FL biology, and also for the development/screening of new genotoxic drugs and therapeutic monoclonal antibodies in lymphoma. Disclosures: Bezombes: Roche: Research Funding. Decaup:Institut de Recherche Roche: Employment. Klein:Roche Glycart AG: Employment. Varoqueaux:F. Hoffman-La Roche AG: Employment. Savina:Roche S.A.S: Employment.

Follicular lymphomas (FLs) account for 35–40% of all adult lymphomas. Treatment typically involves chemotherapy combined with the anti-CD20 monoclonal antibody (MAb) rituximab (RTX). The development of the type II anti-CD20 MAb obinutuzumab (GA101) aims to further improve treatment. Here, using FL cells we show that RTX and GA101 display a similar activity on RL cells cultured in 2D. However, 2D culture cannot mimic tumor spatial organization and conventional 2D models may not reflect the effects of antibodies as they occur in vivo. Thus, we created a non-Hodgkin’s lymphoma (NHL) 3D culture system, termed multicellular aggregates of lymphoma cells (MALC), and used it to compare RTX and GA101 activity. Our results show that both antibodies display greater activity towards FL cells in 3D culture compared with 2D culture. Moreover, we observed that in the 3D model GA101 was more effective than RTX both in inhibiting MALC growth through induction of (lysosomal) cell death and senescence and in inhibiting intracellular signaling pathways, such as mammalian target of rapamycin, Akt, PLCgamma (Phospholipase C gamma) and Syk. Altogether, our study demonstrates that spatial organization strongly influences the response to antibody treatment, supporting the use of 3D models for the testing of therapeutic agents in NHL.