[Efficacy of Chimeric Antigen Receptor T Cell in the Treatment of Refractory/Recurrent B Acute Lymphocytic Leukemia in Children]

Objective: To observe the efficacy of chimeric antigen receptor T cell (CAR-T) in the treatment of children with refractory/recurrent B acute lymphocytic leukemia (B-ALL).

Methods: Thirty-two patients with r/r B-ALL were treated by CAR-T, the recurrence and death respectively were the end point events to evaluate the efficacy and safety of CAR-T.

Results: The median age of the patients was 7.5 (2-17.5) years old; 40 times CAR-T were received in all patients and the median number of CAR-T was 0.9×107/kg; efficacy evaluation showed that 2 cases died before the first evaluation. Thirty patients showed that 3, 6, and 9-moth RFS was (96.3±3.6)%, (81.4±8.6)% and (65.3±12.5)%, respectively, while 3, 6, and 9-month OS was all 100%, and 12, 24-month OS was (94.7±5.1)% and (76±12.8)%. BM blasts≥36% before reinfusion and ferritin peak≥2 500 ng/ml within two weeks of CAR-T cell reinfusion were associated with recurrence. Adverse reactions mainly included cytokine release syndrome (CRS) and CART-cell-related encephalopathy syndrome (CRES), CRS appeared in 26 patients within a week of CAR-T cell reinfusion. CRES reaction was detected in 12 patients. Eighteen patients received intravenous drip of tocilizumab, among them, 12 combined with glucocorticoid. CRS and CRES reactions were relieved within one week after treatment. Hormone dosage was related to the duration of remission in patients, and the cumulative dose of methylprednisolone≥8 mg/kg showed a poor prognosis.

Conclusion: CAR-T is a safe and effective treatment for r/r B-ALL, most CRS and CRES reactions are reversible. BM blasts ≥36% before reinfusion and cumulative dose of methylprednisolone ≥8 mg/kg after reinfusion both affect the therapeutic effect. Ferritin≥2 500 ng/ml within two weeks after reinfusion is related to disease recurrence and is an independent prognostic risk factor.