Regulatory T cells (Tregs) are important therapeutic targets for many immunopathologies. Stimulating Tregs with interleukin-2 (IL-2), the key cytokine supporting Treg fitness, is being actively developed, but is likely to be insufficient to achieve optimal therapeutic efficacy in severe diseases. This is why many groups are developing Treg cell-based therapies, harnessing the experience accumulate during the development of CAR T cell therapies for cancer. In this emerging field, we propose to develop an innovation aimed at generating enhanced-Tregs (e.Tregs) by rendering them IL-2 self-sufficient. We have already proven that, compared to control Tregs, e.Tregs expressing a mutated IL-2 (IL-2N88R) that cannot activate Teffs (i) survive much better in IL-2 deprived environments, (ii) are more stable in phenotype and (iii) have a much better therapeutic efficacy. We will complete the preclinical development of e.Tregs and perform a first-in-man dose-escalation phase-I/II study in chronic graft-versus-host-disease (cGVHD).For this purpose, we will (i) finalize the optimal design of the lentiviral vector to be used, including addition of a suicide gene; (ii) optimize the entire process to select, gene-modify and expand Tregs under good manufacturing practices (GMP) and (iii) perform a dose-escalation phase 1/2 study in patients with cGVHD. The partners are experts in stem cell transplantation and cell therapy who have developed their own academic production of CAR T cells for leukaemia, used in more than 400 patients. They will translate their know-how to e.Tregs.We aim to validate a new therapeutic approach for the treatment of cGVHD, a condition with high mortality and morbidity and unmet clinical needs. Furthermore, we expect that our results will motivate researchers to harness the e.Treg technology in their products, notably CAR Tregs.This should have a major impact by enabling more effective therapies for high-burden diseases or disorders with unmet medical needs.

Overall, our proposal SARA was ranked in Group A. There were only a few comments from the reviewers. One comment was: "Given the high societal relevance of the proposed research, a more effective way of dissemination of project results to society at large is appropriate." In order to improve the visibility and comprehensibility of the dissemination activities within this research project, a work package entitled "training and dissemination" (WP 9) was integrated into the work plan. Therefore, further information on the dissemination can be found in WP 9, but also in the section "Exploitation and dissemination". Dissemination is addressed to both the scientific community and the end-user community. Therefore, it takes place through a variety of channels: Advisory Board, project webpage and brochure, webinars, leaflets and press releases, publications in scientific journals, contributions to international conferences, and presentations at local, regional and national venues. As a further element for dissemination, a Stakeholder Forum will be established. The objective of establishing the Stakeholder Forum is to ensure that key players within the target organisations are aware of the results, its conclusions, and the implications for their monitoring programmes, risk assessment, and policy areas. The members of the Stakeholder Forum represent international health and environmental organisations, European associations of water business companies, European and African waterworks and authorities. Corresponding letters of intent from these stakeholders can be found in the additional information. A second comment referred to the detection of SARS-CoV-2 in water: "Ultimately risk assessment will be related to risks of exposure and the consortium have plentiful expertise here but it will be very helpful to have infectivity assays for Sars." This comment has been taken into account when preparing the tasks of WP 3. In addition to the establishment of alternative, molecular approaches to estimate viral infectivity, selected samples will be examined for the presence of infectious viruses using cell culture techniques. Furthermore, SARS-CoV-2 biomarkers will be analysed not only in wastewater, but also in surface water. In this additional task, analysis by PCR and – for selected samples – by infectivity assays are proposed.