Translational research in radiobiology in the framework of France HADRON national collaboration

France HADRON is a French national collaboration that brings together 26 teams in nine different French cities (Lyon, Caen, Clermont-Ferrand, Paris-Orsay, Nice, Toulouse, Marseille, Strasbourg and Grenoble). This infrastructure was created in 2013 and follows the ETOILE and ARCHADE projects; it is presently funded by public money. Ten teams, from different scientific background, using a wide range of approaches, participate in radiobiology researches upon protons and carbon ion therapy in comparison with photons used in classical radiation oncology. These approaches combine the use of multiple biological models of radioresistant tumors and healthy tissue critical for treatment tolerance. Thus, the determinants of the radioresistance of head and neck squamous cell carcinoma (HNSSC), high-grade gliomas, sarcomas including chondrosarcomas and the ubiquitous endothelial cells and fibroblasts are studied. Multiple methodological approaches are implemented. In particular, these include: the extraction of tumor stem cell populations and their radiobiological comparison with the differentiated tumor cells; the studies in hypoxic and normoxic conditions; the development and the use of models of 3D cell cultures that highlight important differences in cell behaviors; the cell biology with the analysis of typical neoplastic mechanisms such as invasive and cell migration processes, as well as late recovery of irradiated tumor cells that reenter proliferation; the molecular biochemistry with analysis of resistance signaling pathways, telomerase regulation and genomic analysis of predictors of radioresistance in retrospective and prospective series of patients (gliomas, HNSSC, sarcomas) and finally the oxidative stress, genotoxicity and inflammatory measurements in normal human cells at early and late times after irradiation. This work allows a better understanding of the mechanisms of cellular and tumor radioresistance, normal tissue toxicity, but they also enable pre-clinical and clinical approaches. Thus, experimental approaches of combinations of pharmacological treatments acting on the identified resistance or toxicity mechanisms with the different types of radiation studied are developed. The comparison between stem cells and differentiated cells is very interesting in this respect. This information, combined with phenomenological data on survival and relative biological effectiveness (RBE), contributes to the adjustment and parameterization of bio-mathematical predictive models of the cellular response such as the Nanox ® model. This work enables, on the one hand, to suggest hypotheses of clinical trials aimed at acting on tumor radioresistance; and, on the other hand, to integrate into studies associated with prospective transnational clinical research protocols, comparing carbontherapy vs. photon or proton radiotherapy, in collaboration with the European carbontherapy centers, in particular the Heidelberg Ion Therapy (HIT) in Germany and Centro Nazionale di Adroterapia Oncologica (CNAO) in Italy. The potential of France HADRON in radiobiology is important and can make a useful contribution to this field of research, in particular by pursuing a convergence approach of the methods, the models and the topics investigated