Successful application of anti-CD19 CAR-T therapy with IL-6 knocking down to patients with central nervous system B-cell acute lymphocytic leukemia.

Few studies have described chimeric antigen receptor-modified T cell (CAR-T) therapy for central nervous system (CNS) B-cell acute lymphocytic leukemia (B-ALL) patients due to life-threatening CAR-T-related encephalopathy (CRES) safety issues. In this study, CAR-Ts targeting CD19 with short hairpin RNA (shRNA)-IL-6 gene silencing technology (ssCART-19s) were prepared. We conducted a phase 1 clinical trial (ClinicalTrials.gov number, NCT03064269). Three patients with relapsed CNS B-ALL were enrolled, conditioned with the fludarabine and cyclophosphamide for lymphocyte depletion and infused with ssCART-19s for three consecutive days. Clinical symptoms and laboratory examinations were monitored. After ssCART-19 treatment, three patients' symptoms resolved almost entirely. Brain leukemic infiltration reduced significantly based on magnetic resonance imaging (MRI), and there were no leukemic blasts in cerebrospinal fluid (CSF), which was confirmed by cytological and molecular examinations. Additionally, increases in the levels of cytokines and immune cells were observed in the CSF of all patients. Only grade 1 cytokine release syndrome (CRS) manifesting as fever was noted in patients. In conclusion, CAR-Ts with shRNA-IL-6 gene knockdown migrated into the CNS, eradicated leukemic cells and elevated cytokines in CSF with mild, acceptable side effects.