Total body irradiation-free haploidentical peripheral blood stem cell transplantation compared to related and unrelated donor transplantation in pediatrics with acute lymphoblastic leukemia.
Acute lymphoblastic leukemia (ALL) is the most prevalent childhood cancer under the age of 15 years. Despite the recent advances in therapeutic regimens, relapse occurs in 15%-20% of pediatric patients after chemotherapy, and hematopoietic stem cell transplantation (HSCT) is the best treatment option. However, donor availability is one of the major challenges. Over the last decade, haploidentical donor (HID) transplantation has evolved as an alternative option. Herein, we aimed to compare the transplant outcomes in pediatric patients receiving total body irradiation (TBI)-free myeloablative regimens, between non-HID and HID transplant.
The study included 60 pediatric ALL patients who had undergone HSCT from October 2016 until September 2020. Forty-three patients received non-HID HSCT, while 17 patients received HID. The sources of stem cells (SC) were peripheral blood stem cells (PBSC) for all the patients. The conditioning regimen was based on busulfan and cyclophosphamide. For graft-versus-host disease (GvHD) prophylaxis, patients received cyclosporine and methotrexate in the setting of non-HID transplantation, where HIDs received post-transplant cyclosporine and cyclophosphamide.
The cumulative incidences of 3-year overall survival (OS) were 73.1%, 66.6%, and 69.5%, for matched sibling donor-matched related donor (MSD-MRD), matched unrelated donor-mismatched unrelated donor (MUD-MMUD), and HID groups, respectively (p = .85). The cumulative incidences of grade II-IV acute GvHD for the MRD, MUD-MMUD, and HID groups were 29%, 41%, and 49%, respectively (p = .47). Furthermore, the 3-year cumulative incidence of chronic GvHD was MSD-MRD: 70% versus MUD-MMUD: 42% versus HID: 45% (p = .64). The 3-year cumulative incidence of relapse post transplantation was 45%, 18%, and 45%, respectively, for the MSD-MRD, MUD-MMUD, and HID groups, and the differences were not statistically significant (p = .55). There was a higher risk for cytomegalovirus (CMV) infection in patients receiving HID transplants compared to those of non-HIDs (p < .01).
Our results indicate that PBSC-HID transplant outcomes in the setting of non-TBI conditioning are comparable to those of non-HIDs in pediatric ALL patients.
Mardani M
,Behfar M
,Jafari L
,Mohseni R
,Naji P
,Salajegheh P
,Donyadideh G
,Hamidieh AA
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Post-Transplantation Cyclophosphamide-Based Haploidentical versus Matched Unrelated Donor Peripheral Blood Hematopoietic Stem Cell Transplantation Using Myeloablative Targeted Busulfan-Based Conditioning for Pediatric Acute Leukemia.
The use of haploidentical related donors (HRDs) is a common alternative donor strategy used when matched sibling or unrelated donors are not available for hematopoietic stem cell transplantation (HSCT). However, there have been no studies comparing HRD HSCT with post-transplantation cyclophosphamide (PTCy) and matched unrelated donor (MUD) HSCT with antithymocyte globulin using similar busulfan-based myeloablative conditioning regimens in pediatric acute leukemia. Here we compared the outcomes in children and adolescents with high-risk acute leukemia who underwent HRD HSCT with PTCy (n = 35) or MUD HSCT (n = 45) after targeted busulfan-based myeloablative conditioning using intensive pharmacokinetic monitoring. The median duration of follow-up was 3.7 years in the HRD group and 4.6 years in the MUD group. No engraftment failure was observed in either group. There were no significant between-group differences in the cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) (34.3% versus 48.9%; P = .142), grade III-IV acute GVHD (2.9% versus 8.9%; P = .272), moderate to severe chronic GVHD (11.4% versus 18.3%; P = .417), relapse (25.6% versus 28.0%; P = .832), and nonrelapse mortality (0% versus 2.2%; P = .420). The 3-year severe chronic GVHD-free/relapse-free survival (GRFS), leukemia-free survival (LFS), and overall survival (OS) rates in the HRD and MUD groups were 62.9% (95% confidence interval [CI], 45.8% to 80.0%) versus 49.8% (95% CI, 34.9% to 64.7%; P = .318), 74.4% (95% CI, 58.7% to 90.1%) versus 67.5% (95% CI, 53.4% to 81.6%; P = .585), and 88.6% (95% CI, 78.0% to 99.2%) versus 83.7% (95% CI, 72.5% to 94.9%; P = .968), respectively. In a subgroup analysis of patients with acute lymphoblastic leukemia (HRD, n = 17; MUD, n = 26), the 3-year GRFS, LFS, and OS rates in the HRD and MUD groups were 49.4% (95% CI, 24.3% to 74.5%) versus 39.5% (95% CI, 19.7% to 59.3%; P = .601), 61.8% (95% CI, 37.5% to 86.1%) versus 63.6% (95% CI, 44.4% to 82.8%; P = .872), and 82.4% (95% CI, 64.4%, 100%) versus 84.2% (95% CI, 70.1% to 98.3%; P = .445), respectively. In patients with acute myelogenous leukemia (AML) (HRD, n = 16; MUD, n = 16), the 3-year GRFS, LFS, and OS rates in the HRD and MUD groups were 80.8% (95% CI, 61.2% to 100%) versus 61.9% (95% CI, 37.8% to 86.0%; P = .326), 87.1% (95% CI, 70.2% to 100%) versus 73.9% (95% CI, 51.8% to 96.0%; P = .478), and 93.8% (95% CI, 81.8% to 100%) versus 85.6% (95% CI, 67.0% to 100%; P = .628), respectively. Although the difference was not statistically significant and the number of patients was small, the promising outcomes of HRD HSCT in AML patients were encouraging. Our results demonstrate that HRD HSCT with PTCy using a targeted busulfan-based myeloablative conditioning regimen has outcomes similar to those of MUD HSCT with antithymocyte globulin. HRD HSCT with PTCy could be a feasible option for pediatric high-risk acute leukemia patients who lack an HLA-matched related or unrelated donor.
Hong KT
,Park HJ
,Kim BK
,An HY
,Choi JY
,Kang HJ
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