IntroductionRelapse risk after stem cell transplantation (SCT) is a key concern in treating childhood acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML). The choice between bone marrow (BM) and peripheral blood (PB) grafts may influence relapse rates, graft-versus-host disease (GVHD), and overall survival (OS). Current evidence shows that while peripheral blood grafts may slightly lower relapse risk, they are associated with higher GVHD and transplant-related mortality, resulting in no clear survival advantage over BM grafts in children. 1 2 3ObjectivesDescribe differences in OS, event-free survival (EFS): graft failure (GF), graft-versus-host disease (GVHD) and relapses (R), between BM and PB SCT in pediatric and adolescent patients with ALL and AML. MethodsA retrospective review was made in patients with history of ALL or AML who received transplants between January 2014 and December 2024 at the National Institute of Pediatrics in Mexico City. ResultsA total of 120 patients underwent HSCT, of which 90 had ALL and 30 AML. Median age was 8 years in ALL group and 7 years in AML group. In ALL group, 59 were male and 31 females. In AML group, 15 were male and 15 females. Disease status among ALL patients, 31 were in CR1, 50 in CR2, and 9 in CR3. In AML group, 17 were in CR1, 11 in CR2, and 2 in CR3. Donor types in the ALL cohort were: MSD in 41, (PB 32; BM 9), haplo-PTCy in 43 (PB 26; BM 17), CliniMACS in 5, and NRD in 1 patient (BM 1). In AML cohort, MSD was used in 10 patients (PB 7; BM 3), and PTCy in 19 (PB 11; BM 8); 1 patient received SCT from an NRD BM. Median CD34⁺ cell dose was 5 ×10⁶/kg for ALL and 5.1 ×10⁶/kg for AML. Median TNC dose was 4.4 ×10⁸/kg for ALL and 3.79 ×10⁸/kg for AML. GVHD prophylaxis used in ALL included CsA + MTX in 42 patients, PTCy plus Tac + MMF in 43, and CsA alone in 5 patients. In AML there were 10, 19, and 1, respectively. With a median follow-up of 75 months, OS rate for the entire cohort was 60.3%. OS was 58.7% for ALL and 65.5% for AML (p= .610; 95% CI, 63.1–88.5). OS was 58.6% in PB vs 69.2% in BM group (p= .472; 95% CI, 67.0–91.4). Among patients with ALL, OS was 55.6% for PB and 63% for BM (p= .943; 95% CI, 43.0–61.0). No GF was observed in MSD and PB group, while GF rate was 11.1% in BM group. In PTCy group, GF occurred in 19.2% of PB and 52.9% of BM (OR= 4.4; 95% CI, 1.47–13.38; p= .001; 95% CI 61.8–78.9). Grade III–IV aGVHD was observed in 21.8% of patients: 5 (13.9%) in MSD and 12 (28.6%) in PTCy. aGVHD was more frequent in who received PB (36%, OR = 0.625; 95% CI, 0.201–1.940). Relapse OR using BM was 0.51 (p= .134; 95% CI, 0.1–1.7). In the remaining patients with AML, OS was 66.7%, with 72.2% in those receiving PB and 58.3% in BM (p= .154; 95% CI: 62.4–109.7). GF occurred in 14.3% of MSD with PB, and 63.5% in PTCy PB. No GF was observed in either BM group, but this difference did not reach statistical significance (p= .189). III–IV aGVHD occurred in 33.3% of MSD with BM group, whereas no cases were reported in MSD with PB group. In PTCy group III–IV aGVHD occurred in 9.1% of PB and 12.5% of BM (p= .135). Cumulative incidence of relapse using BM as source of HSC was 41.7% (p= .070, OR 1.85, 95% CI: 0.397–8.7). Discussion and ConclusionsOS and EFS rates are similar between BM and PB SCT. For children and adolescents with ALL and AML, BM remains the preferred HSC source for allo-HSCT, primarily because it leads to similar survival outcomes as PB but with lower risks of non-relapse mortality and GVHD. PBSC may still be considered in certain contexts depending on individual patient or donor factors, but the overall data supports a continued preference for BM in this setting.

References Shimosato Y, et al. Allogeneic Bone Marrow Transplantation versus Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies in Children: A Systematic Review and Meta-Analysis. Biol Blood Marrow Transplant. 2020;26(1):88-93.

Kim BK, et al. Comparable outcomes of allogeneic peripheral blood versus bone marrow hematopoietic stem cell transplantation from a sibling donor for pediatric patients. Ann Hematol. 2024;103(6):2051-2058.

Hayashi H, et al. Impact of stem cell selection between bone marrow and peripheral blood stem cells for unrelated hematopoietic stem cell transplantation for hematologic malignancies: on behalf of the Donor/Source Working Group of the Japanese Society for Transplantation and Cellular Therapy. Cytotherapy. 2024;26(2):178-184.

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2025
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