Molecular signatures associated with tumor-specific immune response in melanoma patients treated with dendritic cell-based immunotherapy

// Tamara Garcia-Salum 1, 2 , Andrea Villablanca 1, 2 , Franziska Matthaus 3 , Andres Tittarelli 1, 2 , Mauricio Baeza 4 , Cristian Pereda 1, 2 , M. Alejandra Gleisner 1, 2 , Fermin E. Gonzalez 2, 5 , Mercedes N. Lopez 1, 2 , Jorg D. Hoheisel 6 , Johannes Norgauer 7 , Peter J. Gebicke-Haerter 1, 8 and Flavio Salazar-Onfray 1, 2 1 Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile 2 Millennium Institute on Immunology and Immunotherapy, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile 3 Faculty of Biological Sciences and FIAS, University of Frankfurt, Ruth-Moufang-Strase 1, 60438 Frankfurt am Main, Germany 4 Laboratory of Periodontal Biology, Faculty of Dentistry, Universidad de Chile, 8380492 Santiago, Chile 5 Laboratory of Experimental Immunology and Cancer, Faculty of Dentistry, Universidad de Chile, 8380492 Santiago, Chile 6 Functional Genome Analysis, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany 7 Department of Dermatology, Jena University Hospital D-07743 Jena, Germany 8 Institute of Psychopharmacology, Central Institute of Mental Health, University of Heidelberg, J5, 68159 Mannheim, Germany Correspondence to: Flavio Salazar-Onfray, email: fsalazar@u.uchile.cl Keywords: molecular signatures; immunotherapy; melanoma; CXCR4; CD32 Received: July 28, 2017      Accepted: February 26, 2018     Published: March 30, 2018 ABSTRACT Purpose: We previously showed that autologous dendritic cells (DCs) loaded with an allogeneic heat shock (HS)-conditioned melanoma cell-derived lysate, called TRIMEL, induce T-cell-mediated immune responses in stage IV melanoma patients. Importantly, a positive delayed-type hypersensitivity (DTH) reaction against TRIMEL after vaccination, correlated with patients prolonged survival. Furthermore, we observed that DTH reaction was associated with a differential response pattern reflected in the presence of distinct cell subpopulations in peripheral blood. Detected variations in patient responses encouraged molecular studies aimed to identify gene expression profiles induced after vaccination in treated patients, allowing the identification of new molecular predictive markers. Methods: Gene expression patterns were analyzed by microarrays during vaccination, and some of them confirmed by quantitative real-time reverse transcriptase PCR (qRT-PCR) in the total leukocyte population of a representative group of responder and non-responder patients. New candidates for biomarkers with predictive value were identified using bioinformatics, molecular analysis, and flow cytometry. Results: Seventeen genes overexpressed in responder patients after vaccination respect to non-responders were identified after a mathematical analysis, from which ten were linked to immune responses and five related to cell cycle control and signal transduction. In immunological responder patients, increased protein levels of the chemokine receptor CXCR4 and the Fc-receptor CD32 were observed on cell membranes of CD8+ T and B cells and the monocyte population, respectively, confirming gene expression results. Conclusions: Our study contributes to finding new molecular markers associated with clinical outcome and better understanding of clinically relevant immunological responses induced by anti-tumor DC-vaccines.