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.