1:Laboratorio de investigación en Oncohematología, Fundación de Investigación Biomédica, Hospital Infantil Universitario Niño Jesús, Madrid, 28009, Spain; 2:Unidad de Terapias Avanzadas, Oncología, Hospital Infantil Universitario Niño Jesús, Madrid, 28009, Spain

Treating solid tumours with chimeric antigen receptors-modified T cells (CAR-T cells) has shown limited efficacy due to the lack of cancer-type specific antigens. Dinutuximab is a monoclonal antibody that recognizes a sphingolipid, disialoganglioside GD2, which has limited expression in normal tissues but is overexpressed in paediatric tumours, mainly neuroblastoma (NB). Dinutuximab, an anti-GD2 antibody, is currently standard of care in the treatment of NB. We are exploring the possibility of using Dinutuximab as target element for anti-NB-CAR-T cells. Previously, our group have explored the feasibility of producing CAR-T cells from PBMNCs, CD45RA+ post-apheresis fraction and cord blood using similar protocols of T cell transduction and expansion. In this work we performed a characterization of phenotype and functionality of anti-FITC-CAR-T cells derived from different sources, and the cytotoxic effect against anti-GD2-FITC labelled cell line. First, we analysed different anti-FITC-CAR-T cells products attending to CD4/CD8 composition, effector/memory phenotype, activation markers and VCN. Next, to test CAR-T cell efficiency, we performed cocultures of anti-GD2-FITC labelled cell line with PB/45RA/CB-derived anti-FITC-CAR-T cells at different ratios, in which we analysed the inflammatory cytokines release by LegendPlex and the expression of early activation markers as CD25 and CD134 in CAR-T cells by flow cytometry. Also, we analysed the percentage of dead NB by flow cytometry. In vivo experiments are currently on-going to test the efficacy of CAR-T cells in combination with GD2 treatment. Our strategy may complement the current use of Dinutuximab in the treatment of NB through its combination with a targeted CAR-T cell approach.