Preclinical development grant for a trial of Anti-GD2 chimeric antigen receptor (CAR) transduced T-cells for relapsed or refractory neuroblastoma

BACKGROUND Neuroblastoma is the most common solid tumour in children. Approximately half of patients have high risk disease and poor prognosis despite lengthy and intensive treatment. As a new treatment approach for this aggressive disease we have generated a chimeric antigen receptor (CAR) targeting the neuroblastoma antigen GD2. CAR combine the antigen specificity specificity of monoclonal antibodies with potent T cell activation and can be genetically inserted into a patient's own T cells to induce potent and specific immune responses against tumour. AIMS We wish to perform a clinical trial in relapsed neuroblastoma patients involving retroviral transduction of autologous T cells with a vector encoding 1) a second generation CAR which targets GD2 and contains a CD28 costimulatory domain and 2) a novel suicide gene (activated by Rituximab) to eliminate auto-reactive cells in the event of significant toxicity. To allow regulatory approval of this trial we need to demonstrate function of the final optimised retroviral construct, including efficiency of the suicide gene both in vitro, and in an immunocompetent mouse model of GD2 positive cancer. METHODS The fully optimised vector has already been cloned and basic function demonstrated.We will perform the following experiments Specific killing and antigen specific activation of human T cells transduced with the final construct. Activity will be demonstrated in T cells from 5 different donors against a panel of 5 GD2 positive neuroblastoma cell lines compared with 5GD2 negative control cell lines. Dose dependence and time course of killing of transduced T cells by titrated doses of rituximab will be evaluated by flow cytometry. In vivo experiments will use the GD2 bright CT26 cell line growing as subcutaneous tumours in Balb/c mice. We will confirm our previous data showing CAR-dependent tumour growth inhibition in immunocompetent mice following lymphodepletion and T cell transfer. We will show deletion of CAR expressing T cells in tumour bearing mice following physiologically attainable doses of injected Rituximab. USE OF RESULTS The data demonstrating efficacy of the final optimised vector in vitro and in vivo will be incorporated into the IMP dossier for regulatory submission