Chimeric Antigen Receptor 4SCAR-GD2-Modified T Cells Targeting High-Risk and Recurrent Neuroblastoma: A Phase II Multi-Center Trial in China

Background: Neuroblastoma (NB) is one of the most common childhood malignancies responsible for 15% of pediatric cancer deaths. 70% of children with NB present with high-risk features characterized by severe metastasis and poor long-term survival even if the multimodal intensive combination therapies are used. There is ongoing challenge for developing novel therapeutic strategies for NB. GD2 is a well-characterized tumor antigen in NB. Anti-GD2 antibodies and T cells genetically modified to express GD2-specific chimeric antigen receptor (GD2-CART) have demonstrated anti-cancer activity. Here we report the safety and efficacy of a new generation of GD2-CAR (4SCAR-GD2) targeting high-risk NB with a 1-year follow-up (NCI registrations: NCT02992210 and NCT02765243).

Patients and Methods: Total 34 high-risk NB patients, after confirmation for GD2 expression, are enrolled from 5 hospitals in China. These patients had undergone a series of standard therapies, including surgery, chemo- and radio-therapy before CART treatment. CD3 positive cells were selected from apheresis lymphocytes and activated before lentiviral infection. The cells were transduced with a caspase 9-inducible, safety-engineered lentivector CAR containing multiple intracellular signaling domains: GD2-scFv/CD28/CD27/CD3ζ-iCasp9. Before CART infusion, patients received cyclophosphamide and fludarabine conditioning. The CART infusion dose was at average 1.1x10^6/kg. Toxicity was determined based on NCI common toxicity criteria. The International Neuroblastoma Response Criteria were used to define response after CART treatment. The total observation time for all patients is 1 year after infusion.

Results: GD2 expression was scored 0 to 4 by immunohistochemical staining of tumor sections, and total 142 specimens were stained. The results showed that 9% of specimens were negative and more than 71% scored more than 2. Total 34 patients were infused with 4SCAR-GD2 T cells: 24% of them experienced no adverse reactions (per NCI-CTC v.4.0), 50% had grade 1 and 26% had grade 2 toxicity responses including fever, skin rash and peripheral nerve pain. No grade 3 or 4 toxicity was observed. CART expansion kinetics were monitored by quantitative PCR of CAR in peripheral blood. The 4SCAR-GD2 illustrated long term persistence with the highest level of copy number detected at 30% on day 180 after CART infusion. Marked tumor regression was observed in 2 patients. At 28 days after infusion, by ultrasound the mediastinal and peritoneal tumors in one patient were reduced by 94% and 99.5%, respectively. The other patient had progressive tumor located in retroperitoneum and PET-CT showed shrinking tumor two months after CART treatment; retroperitoneal SUV decreased from 2.5 to 1.5. At the one-year observation point, 38% of patients were in stable disease, 15% had partial response and 47% were in disease progression. The 1-year overall survival rate is 74%.

Conclusion: This multicenter trial demonstrates that the 4SCAR-GD2 T cells are safe and effective for treating high-risk stage IV NB children. The correlations of GD2 expression in tumor, CART kinetics in blood and treatment responses could not be statistically established, suggesting a vast disease heterogeneity. Important therapeutic correlates require a large patient cohort and long-term follow-ups to elucidate.