Anti-GD2 CAR-NKT cells in relapsed or refractory neuroblastoma: updated phase 1 trial interim results

Va24-invariant natural killer T cells (NKTs) have antitumor properties that can be enhanced by transgenic expression of tumor-specific receptors. Here, we report the results of the first-in-human clinical evaluation of autologous NKTs co-expressing a GD2-specific chimeric antigen receptor with interleukin (IL)15 (GD2-CAR.15) in 12 children with neuroblastoma (NB) treated on four dose levels (NCT03294954). Objectives included assessing safety, antitumor activity, and immune response. No dose-limiting toxicities occurred, and one patient had grade 2 cytokine release syndrome resolved by tocilizumab. The overall response rate was 25% (3/12) and disease control rate was 58% (7/12) including four patients with stable disease, two partial responses, and one complete response. CD62L+ NKT frequency in infused products correlated with CAR-NKT expansion in patients and was higher in responders than non-responders (71% vs 35.3%, p=0.002). Singe-cell RNA sequencing analysis identified B cell translocation gene 1 (BTG1) as one of the top upregulated genes in GD2-CAR.15-NKTs after in vitro serial tumor challenge. Genetic gain- and loss-of-function experiments revealed that BTG1 is a key driver of hyporesponsiveness in exhausted NKT and T cells. Crucially, NKTs co-expressing GD2-CAR.15 and BTG1-specific shRNA eradicated metastatic NB in mice. These results indicate that CAR-NKTs are safe, produce objective responses in NB patients, and that targeting BTG1 can enhance their therapeutic potency. Overall design: Single-cell RNA sequencing analysis of differently regulated genes in GD2-CAR.15-NKTs between pre-infusion and post-infusion cells.