Chimeric antigen receptor T cell therapy has changed outcomes for children and young adults with relapsed or refractory CD19-positive B-cell acute lymphoblastic leukaemia, producing deep, often measurable-residual-disease-negative remissions even after failed chemotherapy or transplant. It is delivered only at designated centres under a strict clinical pathway. This review is aimed squarely at the paediatrician who will see the child afterwards.
The acute toxicities belong to the centre: cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome. The longer-term problems come home. Prolonged cytopenias, sustained infection risk, B-cell aplasia and hypogammaglobulinaemia requiring immunoglobulin replacement are all consequences of the treatment working as designed — CD19 is on normal B cells as well as malignant ones.
Relapse also remains frequent, through loss of CAR-T persistence or antigen escape, which means a child in remission after CAR-T is under surveillance rather than cured. For a shared-care paediatrician the practical content is knowing that a febrile child with B-cell aplasia and hypogammaglobulinaemia is functionally immunodeficient regardless of how well they look, that immunoglobulin replacement is not optional, and that vaccine responses cannot be assumed.
- Treat fever in a post-CAR-T child as fever in an immunodeficient child, whatever the blood count
- Confirm immunoglobulin replacement is continuing and check trough levels
- Do not assume vaccine responses; B-cell aplasia may persist for months or longer
- Know the designated centre's contact route before you need it
- Explain to families that remission after CAR-T means surveillance, not discharge
Why it matters
The toxicity that reaches the general paediatrician is not the dramatic one, and it lasts far longer.
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