CCNF presented the abstract awards in cancer research this year in Prague. Here are the top three 2017 Best Abstract Award Winners:
IL-33 inhibits melanoma growth and pulmonary metastasis in mice through recruitment and activation of eosinophils
Valeria Lucarini1, Giovanna Ziccheddu1, Iole Macchia1, Valentina La Sorsa1, Francesca Peschiaroli1, Carla Buccione1, Antonella Sistigu2, Sara Andreone1, Claudia Afferni3, Fabrizio Mattei1 and Giovanna Schiavoni1
1Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy.
2Regina Elena National Cancer Institute, Rome, Italy.
3Department of Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
The alarmin IL-33 is an IL-1 family-member that plays pleiotropic roles in allergy, autoimmunity and inflammation through binding to its specific receptor ST2. Emerging evidences suggest an involvement of this cytokine also in cancer immunity, although its function remains ill-defined. In this study, we have investigated the role of IL-33/ST2 axis in anti-tumor response to melanoma. C57Bl/6 mice were implanted subcutaneously with B16.F10 melanoma cells and injected with intraperitoneal IL-33. Tumor growth was monitored and tumor-immune infiltrates were examined by flow cytometry and qPCR. Injection of IL-33 resulted in significant tumor growth delay and this effect was associated with intratumoral accumulation of CD8 T cells and eosinophils, decrease of immunosuppressive myeloid cells, and a mixed Th1/Th2 cytokine expression pattern with local and systemic activation of CD8 T and NK cells. Moreover, intranasal administration of IL-33 determined eosinophil recruitment and a mixed Th1/Th2 cytokine expression pattern in the lung that prevented the onset of pulmonary metastasis after intravenous injection of melanoma cells. This effect was ST2-dependent, since ST2-deficient mice failed to respond to IL-33 and developed pulmonary metastasis at even higher extent than wild-type counterparts. Depletion of eosinophils by in vivo treatment with anti-Siglec-F antibody abolished the ability of IL-33 to both restrict primary tumor growth and metastasis formation. Finally, IL-33 was able to activate eosinophils resulting in efficient killing of target melanoma cells, suggesting a direct anti-tumor activity of eosinophils following IL-33 treatment. Our results identify a previously unrecognized eosinophil-dependent anti-tumor mechanism triggered by IL-33/ST2 axis that restricts melanoma growth and metastasis. Our findings may open perspectives for novel combined cancer immunotherapy strategies.
Olfactory receptor signaling as a novel immune checkpoint in solid tumors
Tillmann Michels12, Christina A. Hartl1, Nisit Khandelwal1, Marco Breinig1, Antonio Sorrentino12, Valentina Volpin1, Christina Mäder1, Ayse-Nur Menevse12, Ludmila Umansky1, Isabel Poschke1, Rink Offringa1, Vladimir M. Milenkovic3, Christian Wetzel3, Michael Boutros1, Galit Eisenberg4, Michal Lotem4 and Philipp Beckhove12
1German Cancer Research Center (DKFZ), Heidelberg, Germany; 2Regensburg Center for Interventional Immunology (RCI), Regensburg, Germany; 3Molecular Neuroscience, University of Regensburg, Regensburg, Germany; 4Hadassah Hebrew University Hospital, Sharett Institute of Oncology, Jerusalem, Israel.
Immune checkpoint blockade is considered a breakthrough in cancer therapy but the plethora of suppressive mechanisms employed by tumors to evade immune destruction are yet to be understood and matched by today’s immunotherapy treatments. Recently, our group established a siRNA-based high throughput RNAi screening to unravel the arsenal of immune checkpoints utilized by tumors. We thereby identified potential candidates using patient-derived tumor-infiltrating lymphocytes (TILs) in conjunction with primary HLA-matched melanoma cells screening a library of around 2800 kinases and surface-associated genes.
Briefly, M579-A2 melanoma cells were reversely transfected with the siRNA library and then co-cultured with MART1- and gp100-specific TILs to determine TIL-mediated lysis. Our screening identified 73 candidates that negatively regulated TIL-mediated cytotoxicity. Interestingly, several of the candidate genes and gene families were found in related screenings in pancreatic adenocarcinoma and myeloma as well, suggesting shared modes of action. To streamline our discovery process for large scale libraries, we established a secondary screen assaying multiple T cell activation markers, including effector cytokines.
Among the strongest candidates from our primary screenings were olfactory receptors and associated genes involved in GPCR signaling via cAMP. For example, knockdown of TiMi1 (name altered) – a surface receptor of the class of olfactory GPCRs – increased TIL-mediated killing in melanoma, PDAC and colorectal carcinoma. Furthermore, TiMi1 knockdown increased TIL activity measured by production of type 1-assocated cytokines and reduced T cell apoptosis. We validated the role of TiMi1 as an immune checkpoint in vivo using a xenograft mouse model in combination with adoptive cell transfer.
We aimed to understand how TiMi1 affects T cell activity. Therefore we performed mode of action analysis which revealed that TiMi1-mediated inhibition of TILs functions by altering cAMP-dependent signaling inside T cells. Protein kinase alpha (PKA) is activated by cAMP and in turn activates C-terminal Src kinase (Csk) which inhibits lymphocyte-specific protein tyrosine kinase (Lck) by phosphorylation.
Preliminary experiments suggest that TiMi1 alters the balance between G-Protein alpha i (Gαi) and G-Protein alpha s/olfactory (Gαs/olf) signaling inside tumor cells depending on the encounter of TILs. The resulting TiMi1-dependent signaling leads to the transport of cAMP from the tumor to the T-cell and finally to the inhibition of Lck.
In summary, we established a discovery platform aiding the search for immune checkpoint candidates. Our novel antigen-specific screening approach identified TiMi1 and olfactory signaling as an inhibitory pathway against T cell responses by differential regulation of cAMP-dependent signaling inside TILs.
Peptide vaccination against PD-L1 in multiple myeloma
Nicolai Grønne Jørgensen1,3, Shamaila Munir Ahmad1, Inge Marie Svane1,2, Lene Meldgaard Knudsen3, Mads Hald Andersen1
1Center for Cancer Immunotherapy (CCIT), Department of Hematology, Herlev and Gentofte Hospital, Herlev, Denmark, 2Department of Oncology, Herlev and Gentofte Hospital, Herlev, Denmark, 3Department of Hematology, Herlev and Gentofte Hospital, Herlev, Denmark.
The role of immunotherapy in multiple myeloma is well established – from the use of thalidomide and its analogs to the recent approval of anti-CD38- and anti-SLAMF7-antibodies. Recent trials indicate that antibodies against the checkpoint molecule programmed death-1 (PD-1) have activity against multiple myeloma. The PD-1 ligand PD-L1 is upregulated on myeloma cells and the surrounding microenvironment. The PD-1/PD-L1 interaction renders T cells exhausted, and blockade of the PD-1/PD-L1 antagonizes this exhaustion.
We have recently described the presence of spontaneously occurring PD-L1 specific cytotoxic T-cells, which recognize both PD-L1 expressing immune cells and malignant cells. We have further shown that these “anti-regulatory” T cells improve the function of other T cells, in addition to their ability to kill PD-L1 positive cancer cells directly. Boosting PD-L1 specific T cells would thus lead to cytotoxicity against both immunoregulatory cells and cancer cells. The ability of the induced PD-L1 specific T cells to release pro-inflammatory cytokines in the tumor microenvironment supports additional antineoplastic immunity. As such PD-L1 may be targeted by a vaccine comprising PD-L1 peptide and we have initiated a first-in-human phase I study with peptide vaccination against PD-L1 in patients with multiple myeloma following high dose melphalan with autologous stem cell transplantation (HDT). We plan to include a total of 10 patients. Primary end points will be safety and toxicity and we will concurrently conduct immune monitoring of the patients to investigate the possible phenotypic and functional changes inferred by the vaccine.
View the presentations online here.