TCR α+β+/CD19+ cell–depleted hematopoietic stem cell transplantation for pediatric patients

TCR α⁺β⁺/CD19⁺ cell depletion is an emerging technique for ex vivo graft manipulation in HSCT. We report 20 pediatric patients who underwent TCR α⁺β⁺/CD19⁺ cell–depleted HSCT in four Australian centers. Conditioning regimen was dependent on HSCT indication, which included immunodeficiency (n = 14), Fanconi anemia (n = 3), and acute leukemia (n = 3). Donor sources were haploidentical parent (n = 17), haploidentical sibling (n = 2), or matched unrelated donor (n = 1). Mean cell dose was 8.2 × 10⁸/kg TNC, 12.1 × 10⁶/kg CD34⁺ cells, and 0.4 × 10⁵/kg TCR α⁺β⁺ cells. All patients achieved primary neutrophil and platelet engraftment, with average time to neutrophil engraftment 11 days (range 8‐22) and platelet engraftment 24 days (range 12‐69). TRM at 1 year was 15%. Rate of grade II‐IV aGVHD at 1 year was 20% with no grade III‐IV aGVHD seen. CMV reactivation occurred in 81% of CMV‐positive recipients, with one patient developing CMV disease. Average time to CD4 recovery (>400 × 10⁶/L) was 258 days. Overall survival for the cohort at 5 years was 80%. This report highlights the initial experience of TCR α⁺β⁺/CD19⁺ cell–depleted HSCT in Australian centers, with high rates of engraftment, low rates of aGVHD, and acceptable TRM.