Improving Outcomes with Haploidentical Stem Cell Transplantation [HaploSCT] in Children Using Post-transplant Cyclophosphamide: a Single Center Experience

Haplo-identical stem cell transplant using post-transplant cyclophosphamide is increasingly being used in children without a matched sibling donor. Between 2010 and June 2021, 127 children underwent 138 transplants with a median age of 7.1 years for malignant and non-malignant disorders. Conditioning regimens included both myeloablative and reduced intensity regimens with peripheral blood stem cells as the main graft source. Engraftment occurred in 113 [81.9%] at a median of 16 days [range: 10–32] with primary graft failure in 10.2%. Cumulative incidence of grade II–IV acute graft versus host disease (GVHD) was 49.5% and chronic GVHD in 40.7%. Majority [92.7%] had at least one infection with 31% incidence of bacterial infection, 76% incidence of viral and 16% incidence of fungal infection. The 2-year overall survival (OS) is 54.9 ± 4.6% with a lower survival among young children aged 0–5 years [28.2 ± 6.4%] compared to 5–10 years [71.3 ± 6.8%] and 11–15 years [55.7 ± 8.8%] [p = 0.032]. 2-year OS has gradually improved from 25.0 ± 2.1% for 2010–2013 to 47.5 ± 6.2% for 2014–2017 and 67.1 ± 6.6% for 2018–2021 [ p = 0.049]. On multivariate analysis, bacterial infection [ p = 0.017], invasive fungal disease [ p = 0.002] and graft failure [ p = 0.029] negatively impacted overall survival. Haplo-identical SCT with post-transplant cyclophosphamide is a reasonable option for children who do not have a matched sibling donor. Strategies to reduce graft failure, infection related mortality and GVHD needs to be explored.