Introduction
Chimeric antigen receptor T lymphocytes (CAR-T) targeting the CD19 surface antigen have led to durable remissions in children and young adults with refractory and/or multiply relapsed B-lymphoblastic leukemia (B-ALL).1-11 Pediatric trials of CD19-directed CAR-T have shown complete response rates up to 89% with one-year event-free survival around 50%.1-4,12 Historically, consolidative allogeneic hematopoietic stem cell transplant (HSCT) has been required to cure refractory and relapsed B-ALL, and CAR-T may be used as a bridge to HSCT. However, CAR-T has resulted in long-term remissions for some patients without the need for further therapy, although the ability to predict response is limited.4,5 CAR-T is an appealing option for heavily pretreated patients unqualified for transplant, or patients at high risk of transplant-related toxicities.13,14 Most post-CAR-T relapses occur within the first year following infusion, and the role of CAR-T reinfusion for the treatment of post-CAR-T relapse is unclear.15 Here we report an unusual case of reinfusions achieving durable remission despite failure to re-achieve B-cell aplasia (BCA). For comparison, we briefly update the experience of seven additional children with relapsed or refractory B-ALL, who were reinfused with an additional dose of tisagenlecleucel, manufactured at the same time as the original dose.