The humanized anti-human AMHRII mAb 3C23K exerts an anti-tumor activity against human ovarian cancer through tumor-associated macrophages

International audienceMüllerian inhibiting substance, also called anti-Müllerian hormone (AMH), inhibits proliferation and induces apoptosis of AMH type II receptor-positive tumor cells, such as human ovarian cancers (OCs). On this basis, a humanized glyco-engineered monoclonal antibody (3C23K) has been developed. The aim of this study was therefore to experimentally confirm the therapeutic potential of 3C23K in human OCs. We first determined by immunofluorescence, immunohistochemistry and cytofluorometry analyses the expression of AMHRII in patient's tumors and found that a majority (60 to 80% depending on the detection technique) of OCs were positive for this marker. We then provided evidence that the tumor stroma of OC is enriched in tumor-associated macrophages and that these cells are responsible for 3C23K-induced killing of tumor cells through ADCP and ADCC mechanisms. In addition, we showed that 3C23K reduced macrophages induced-T cells immunosuppression. Finally, we evaluated the therapeutic efficacy of 3C23K alone and in combination with a carboplatin-paclitaxel chemotherapy in a panel of OC Patient-Derived Xenografts. In those experiments, we showed that 3C23K significantly increased the proportion and the quality of chemotherapy-based in vivo responses. Altogether, our data support the potential interest of AMHRII targeting in human ovarian cancers and the evaluation of 3C23K in further clinical trials

Characterization of Breast Cancer Preclinical Models Reveals a Specific Pattern of Macrophage Polarization

<div><p>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.</p></div

Histology and immunohistochemistry of myofibroblasts and endothelial cells in human and mouse breast cancer tumors.

<p>Slides stained with hematoxylin, eosin and safranin (HES) and Masson’s trichrome, and stained for α-SMA and CD31: (<b>a</b>) human PDXs and (<b>b</b>) murine PyMT and ErbB2 tumors (original magnification: 400x).</p

M1/M2 macrophage-like cell phenotype in BC tumors.

<p>(<b>a</b>) The expression of genes associated with the M1 (MHC-II, CD86, Cd11c, Il1b, Cxcl10 and Cxcl11) or M2 (Mrc1, Scara4, Scarb3, Arg1, Igf1 and Ccr2) phenotype was assessed by the dissociation of five tumors (MMTV-PyMT, BC-PyMT, HBCx-5, -24 and -34), the sorting of macrophage-like cells, and microarray analysis. Levels of gene expression in BC models were compared in unpaired Student’s <i>t</i>-tests (<b>b</b>) Protein levels for M1 (MHC-II and Cd11c) and M2 (Mrc1) markers on macrophage-like cells from the five tumors MMTV-PyMT, BC-PyMT, HBCx -5, -24 and x-34), as measured by flow cytometry. Three tumors were analyzed per model. For each model, Mann-Whitney tests were performed to compare the results obtained with those for the MMTV-PyMT tumor (* <i>p</i>< 0.05, **<i>p</i> <0.01, ***<i>p</i> <0.001). (<b>c</b>) Examples of flow cytometry findings for the levels of M1 and M2 marker proteins (the corresponding isotype is shown in gray).</p

Transcriptome profiles of macrophage-like cells in BC tumors.

<p>(<b>a</b>) Results of principal component analysis (PCA) for the subset of 1238 genes up- or downregulated in at least one comparison between MMTV-PyMT and BC-PyMT, HBCx-5, -24 or -34. The 15 samples, triplicates of MMTV-PyMT (green), BC-PyMT (orange), HBCx-5 (red), HBCx-24 (yellow) and HBCx-34 (blue), were projected oton the first three principal components, which accounted for ~58% of the total variability. Hierarchical clustering of the genes from the (<b>b</b>) “Immune system process” or (<b>c</b>) “Metabolic process” pathways from Gene Ontology analysis identified as significantly up- or downregulated in at least one comparison between BC-PyMT and HBCx-5, -24 and -34.</p

Erosion of the chronic myeloid leukaemia stem cell pool by PPARγ agonists

International audienceWhether cancer is maintained by a small number of stem cells or is composed of proliferating cells with approximate phenotypic equivalency is a central question in cancer biology. In the stem cell hypothesis, relapse after treatment may occur by failure to eradicate cancer stem cells. Chronic myeloid leukaemia (CML) is quintessential to this hypothesis. CML is a myeloproliferative disorder that results from dysregulated tyrosine kinase activity of the fusion oncoprotein BCR-ABL. During the chronic phase, this sole genetic abnormality (chromosomal translocation Ph(+): t(9;22)(q34;q11)) at the stem cell level causes increased proliferation of myeloid cells without loss of their capacity to differentiate. Without treatment, most patients progress to the blast phase when additional oncogenic mutations result in a fatal acute leukaemia made of proliferating immature cells. Imatinib mesylate and other tyrosine kinase inhibitors (TKIs) that target the kinase activity of BCR-ABL have improved patient survival markedly. However, fewer than 10% of patients reach the stage of complete molecular response (CMR), defined as the point when BCR-ABL transcripts become undetectable in blood cells. Failure to reach CMR results from the inability of TKIs to eradicate quiescent CML leukaemia stem cells (LSCs). Here we show that the residual CML LSC pool can be gradually purged by the glitazones, antidiabetic drugs that are agonists of peroxisome proliferator-activated receptor-γ (PPARγ). We found that activation of PPARγ by the glitazones decreases expression of STAT5 and its downstream targets HIF2α and CITED2, which are key guardians of the quiescence and stemness of CML LSCs. When pioglitazone was given temporarily to three CML patients in chronic residual disease in spite of continuous treatment with imatinib, all of them achieved sustained CMR, up to 4.7 years after withdrawal of pioglitazone. This suggests that clinically relevant cancer eradication may become a generally attainable goal by combination therapy that erodes the cancer stem cell pool