Harnessing crossreactivity of cytomegalovirus-reactive γδ T cells for immunotherapy in childhood neuroblastoma: a preclinical study

Abstract

BackgroundNeuroblastoma is the commonest cancer in infants. Survival in high-risk groups is low (40–50%). Newer treatments are needed to improve survival and morbidity. Cytomegalovirus (CMV) is a common viral infection, which increases γδ T cells. We investigated the use of CMV-reactive γδ T cells as a potential new immunotherapy. MethodsPeripheral blood mononuclear cells from 30 paediatric haemato-oncology patients with or without CMV infection were analysed by flow cytometry. γδ T cells were expanded, and then co-cultured with CMV targets or neuroblastoma cells. T-cell activation, cytokine secretion, killing activity, and mechanisms were determined by ELISA, MTT colorimetric assay, and blocking assays. Novel γδ T cell receptors (TCR) were identified by sequencing. FindingsIn paediatric haemato-oncology patients, acute CMV led to higher proportions of total γδ T cells (p=0·0002) with the dominant subtype Vδ1 (p=0·0035). CMV-reactive γδ T cells were of the effector memory phenotype and expanded to clinically significant numbers for adoptive transfer. When compared with γδ T cells from CMV-negative patients, CMV-reactive γδ T cells had statistically significantly higher interferon γ release (p<0·001) in co-cultures with CMV-infected fibroblasts and showed cytolytic activity against CMV-infected fibroblasts and neuroblastoma cells which was mediated by γδ TCR and the NKG2D receptor. Sequencing showed that the dominant γδ T-cell chains in CMV-infected patients were Vδ1 Vγ2. Within the TCRs, CDR3 sequences had minimal diversity, γ chains had wide variations, and we identified a novel subpopulation in some patients. InterpretationWe show that acute CMV infection in paediatric haemato-oncology patients leads to an increase in the Vδ1 Vγ2 subtype of γδ T cells. They can be expanded for adoptive transfer and are likely to retain killing ability post expansion. They recognise and kill CMV-infected targets and neuroblastoma cells via the γδ TCR and the NKG2D receptor. We have identified a novel TCR in a subpopulation of CMV-positive patients. FundingGreat Ormond Street Charity, National Institute for Health Research Biomedical Research Centre, Olivia Hodson Cancer Fund.