Contributions
Abstract: EP1293
Type: E-Poster Presentation
Session title: Stem cell transplantation - Clinical
Background
The application of haploidentical stem cell transplantation (haplo-SCT) greatly broadens the choice of donor pools for recipients of hematopoietic stem cell transplantation (HSCT). Recent evidence suggests that high donor-specific antibody (DSA) titer is one of the leading causes of graft failure that may contribute to higher transplant-related mortality and modality. Several approaches have been developed to reduce DSA. However, there is no available consensus or standard guidelines for the reduction of DSA for HSCT recipients due to limited evidence in published data.
Aims
Our aims are to investigate the outcomes of pediatric haplo-SCT recipients with high DSA titers using a desensitizing conditioning chemotherapy regimen.
Methods
Fourteen candidates of haplo-SCT aged 2 to 17 (median 8 years of age) were tested to have high DSA titers (HLA type I and/or HLA type II, MFI≥4000) between January 2020 and September 2020. Primary diseases included thalassemia major (13 in 14 patients) and severe aplastic anemia (1 in 14 patients). The conditioning protocol consisted of a cyclophosphamide-busulfan-based myeloablative regimen and was selectively given one or more approaches to reduce DSA titer, including high-dose intravenous immunoglobulin, rituximab, bortezomib, and plasma exchange. The GVHD prophylaxis consisted of post-transplant cyclophosphamide, mycophenolate mofetil, and tacrolimus.
Results
Clinical data of 2 girls and 12 boys were analyzed. Haplo grafts were collected from the siblings (5/14), fathers (8/14), and mothers (1/14). The mean CD34+ cell dose was 12.52 × 106/kg. Neutrophil and platelet engraftment was achieved at a median of 20 days (range, 8-33 days) and 20 days (range, 8-40 days), respectively. No patients had graft failure nor had developed poor graft function. Only two patients developed grade I-II acute graft-versus-host disease (GVHD), and no chronic GVHD was observed. Viremia of cytomegalovirus (CMV) and Epstein-Barr virus was observed in three and two patients, respectively. However, none of these patients had CMV diseases or post-transplantation lymphoproliferative disorder. No other transplant-related complications were observed. All patients were alive without chronic complications at the time of last follow-up (median follow-up period 243 days, range 164 to 334 days).
Conclusion
This preliminary data suggest that our approach to use a desensitizing conditioning regimen for pediatric recipients of haplo-SCT is safe and practical to limit graft failure and transplant-related complications and may contribute to a larger cohort study in the future.
Keyword(s): Haploidentical stem cell transplantation, Pediatric, Transplant-related mortality
Abstract: EP1293
Type: E-Poster Presentation
Session title: Stem cell transplantation - Clinical
Background
The application of haploidentical stem cell transplantation (haplo-SCT) greatly broadens the choice of donor pools for recipients of hematopoietic stem cell transplantation (HSCT). Recent evidence suggests that high donor-specific antibody (DSA) titer is one of the leading causes of graft failure that may contribute to higher transplant-related mortality and modality. Several approaches have been developed to reduce DSA. However, there is no available consensus or standard guidelines for the reduction of DSA for HSCT recipients due to limited evidence in published data.
Aims
Our aims are to investigate the outcomes of pediatric haplo-SCT recipients with high DSA titers using a desensitizing conditioning chemotherapy regimen.
Methods
Fourteen candidates of haplo-SCT aged 2 to 17 (median 8 years of age) were tested to have high DSA titers (HLA type I and/or HLA type II, MFI≥4000) between January 2020 and September 2020. Primary diseases included thalassemia major (13 in 14 patients) and severe aplastic anemia (1 in 14 patients). The conditioning protocol consisted of a cyclophosphamide-busulfan-based myeloablative regimen and was selectively given one or more approaches to reduce DSA titer, including high-dose intravenous immunoglobulin, rituximab, bortezomib, and plasma exchange. The GVHD prophylaxis consisted of post-transplant cyclophosphamide, mycophenolate mofetil, and tacrolimus.
Results
Clinical data of 2 girls and 12 boys were analyzed. Haplo grafts were collected from the siblings (5/14), fathers (8/14), and mothers (1/14). The mean CD34+ cell dose was 12.52 × 106/kg. Neutrophil and platelet engraftment was achieved at a median of 20 days (range, 8-33 days) and 20 days (range, 8-40 days), respectively. No patients had graft failure nor had developed poor graft function. Only two patients developed grade I-II acute graft-versus-host disease (GVHD), and no chronic GVHD was observed. Viremia of cytomegalovirus (CMV) and Epstein-Barr virus was observed in three and two patients, respectively. However, none of these patients had CMV diseases or post-transplantation lymphoproliferative disorder. No other transplant-related complications were observed. All patients were alive without chronic complications at the time of last follow-up (median follow-up period 243 days, range 164 to 334 days).
Conclusion
This preliminary data suggest that our approach to use a desensitizing conditioning regimen for pediatric recipients of haplo-SCT is safe and practical to limit graft failure and transplant-related complications and may contribute to a larger cohort study in the future.
Keyword(s): Haploidentical stem cell transplantation, Pediatric, Transplant-related mortality