No Impact of Total or Myeloid Cd34+ Cell Numbers on Neutrophil Engraftment and Transplantation-Related Mortality after Allogeneic Pediatric Bone Marrow Transplantation

Effects of CD34+ cell dose on engraftment and long-term outcomes after allogeneic bone marrow transplantation

BACKGROUND

The number of CD34+ cells in the graft is generally associated with time to engraftment and survival in transplantation using cord blood or allogeneic peripheral blood stem cells. However, the significance of abundant CD34+ in bone marrow transplantation (BMT) remained unclear.

METHODS

We retrospectively reviewed 207 consecutive adult patients who underwent their first BMT at Jichi Medical University between January 2009 and June 2021.

RESULTS

The median nucleated cell count (NCC) and CD34+ cell dose were 2.17 × 108/kg (range .56-8.52) and 1.75 × 106/kg (.21-5.84), respectively. Compared with 104 patients in the low CD34+ group (below the median), 103 patients in the high CD34+ group (above the median) showed faster engraftment at day +28 in terms of neutrophil (84.6% vs. 94.2%; p =  .001), reticulocyte (51.5% vs. 79.6%; p < .001), and platelet (39.4% vs. 72.8%; p < .001). There were no significant differences in overall survival, relapse, nonrelapse mortality, acute or chronic graft-versus-host disease, or infectious complications between the two groups in univariate and multivariate analyses. Low or high NCC had no significant effect on overall survival, nonrelapse mortality, cumulative incidence of relapse and graft-versus-host disease, either. While a positive correlation was observed between NCC and the CD34+ cell dose, a high CD34+ cell dose was associated with rapid hematopoietic recovery, even in patients with NCC below the median.

CONCLUSION

Measurement of CD34+ cell dose in addition to NCC was useful for predicting hematopoietic recovery, but seemed to have little influence on the long-term outcome in BMT.

Effects of CD34+ cell dose on haematopoietic recovery in acute lymphoblastic leukaemia patients with positive pretransplant measurable residual disease

INTRODUCTION

A higher CD34⁺ cell dose in allografts is associated with faster haematopoietic recovery after allogeneic haematopoietic stem cell transplantation (allo-HSCT). Leukaemia stem cells impair normal bone marrow (BM) niches and induce BM failure during leukemogenesis. However, whether measurable residual disease (MRD), known as the persistence of low-level leukaemic cells, could influence the effects of CD34⁺ cell dose on haematopoietic recovery after transplantation in acute lymphoblastic leukaemia (ALL) patients is unknown.

METHODS

A total of 975 ALL patients were enrolled and classified into pre-HSCT MRD-positive and MRD-negative subgroups. Cox proportional hazard regression models were built for time-to-event outcomes. Multivariate analysis was performed to determine independent influencing factors from the univariate analysis.

RESULTS

An appropriate CD34⁺ cell dose was positively associated with faster haematopoietic recovery in the total ALL population. More importantly, in pre-HSCT MRD-positive ALL patients, a higher CD34⁺ cell dose (≥2.76 × 10⁶ /kg) was related to faster neutrophil (HR 1.330, 95% CI 1.045-1.692, p = 0.021) and platelet engraftment (HR 1.808, 95% CI 1.412-2.316, p < 0.001) in multivariate analysis. CD34⁺ cell dose was a crucial factor associated with either engraftment or transplant outcomes, although we did not demonstrate direct correlations of CD34⁺ cell dose with relapse, TRM, LFS or OS after allo-HSCT.

CONCLUSION

Our results indicated that no additional CD34⁺ stem and progenitor cell harvests were needed to ensure successful haematopoietic recovery in pre-HSCT MRD-positive patients compared to pre-HSCT MRD-negative patients.

Total nucleated cell dose in graft is a better prognostic factor for survival in pediatric patients transplanted with bone marrow compared to CD34+, CD3+, or total mononuclear cell count

BACKGROUND

Most studies investigating the impact of graft composition on transplant-related outcomes have focused on the effect of CD34+ cell dose and reported equivocal results. The aim of this study is to investigate the impact of doses of total nucleated cells (TNCs), total mononuclear cells (TMCs), CD3+, and CD34+ cells on the outcome of children receiving allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

Children and adolescents who underwent allogeneic HSCT for malignant hemato-oncological diseases or nonmalignant diseases in Cukurova University Faculty of Medicine, Pediatric Bone Marrow Transplantation Center between 2010 and 2020 were enrolled in the study.

RESULTS

A total of 212 patients receiving allogeneic HSCT (154 bone marrow transplantation; 58 peripheral blood stem cell transplantation) from matched related or unrelated donors were included in the study. Higher TNC doses associated with a superior 5-year event-free survival (EFS; 67.7% vs 44.7%) in the whole group (log-rank P = .027). Overall survival (OS) and EFS of bone marrow-transplanted patients differed significantly according to TNC doses (log-rank P = .041 and .027, respectively). Multivariant analysis for OS revealed a P value of .038 for TNC, Exp(B) = 1.939 (95% CI: [1.038, 3.621]). That for EFS revealed a P value of .025 for TNC, Exp(B) = 1.992 (95% CI: [1.088, 3.647]). There was no relationship between doses of CD34+ cells, CD3+ cells, TMC, TNC, and neutrophil or platelet engraftment.

CONCLUSION

Our data suggest that TNC dose is a better prognostic factor for pediatric allogeneic HSCT outcomes than doses of CD34+ cells, CD3+ cells, or TMC in patients transplanted with bone marrow. Future studies analyzing cell subsets and other components in TNC could elaborate the factor(s) accompanying this observed survival advantage.

Allogeneic hematopoietic stem cell transplantation from unrelated donors is associated with higher infection rates in children with acute lymphoblastic leukemia-A prospective international multicenter trial on behalf of the BFM-SG and the EBMT-PDWP

Severe infections (SI) significantly impact on non‐relapse mortality after hematopoietic stem cell transplantation (HSCT). We assessed 432 children and adolescents with acute lymphoblastic leukemia (ALL) after total body irradiation based myeloablative HSCT within the multicenter ALL‐BFM‐SCT 2003 trial for SI grade 3 or higher according to common terminology criteria for adverse events. A total 172 patients experienced at least one SI. Transplantation from matched unrelated donors (MUD) was associated with any type of SI in the pre‐engraftment period (hazard ratio [HR]: 2.57; P < .001), and with any SI between day +30 and + 100 (HR: 2.91; P = .011). Bacterial (HR: 2.24; P = .041) and fungal infections (HR: 4.06; P = .057) occurred more often in the pre‐engraftment phase and viral infections more often before day +30 (HR: 2.66; P = .007) or between day +30 and + 100 (HR: 3.89; P = .002) after HSCT from MUD as compared to matched sibling donors. Chronic GvHD was an independent risk factor for any type of SI after day +100 (HR: 2.57; P < .002). We conclude that allogeneic HSCT from MUD in children and adolescents with pediatric ALL is associated with higher infection rates, which seems attributable to an intensified GvHD prophylaxis including serotherapy and methotrexate.

Risk Factors for Transplant Outcomes in Children and Adolescents with Non-Malignant Diseases Following Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND The objective of this study was the analysis of transplant outcomes and survival in children treated with allogeneic hematopoietic cell transplantation (alloHCT) for non-malignant disorders, with a focus on risk factor analysis of transplant-related mortality (TRM). MATERIAL AND METHODS The treatment outcome was analyzed retrospectively in 10 consecutive years in 4 pediatric transplant centers in Poland. To compare the outcomes, patient data were analyzed according to the diagnosis, age at transplant, donor type, stem cell source, conditioning regimens, transplanted CD34+ cells dose, and pediatric TRM score. RESULTS From 183 analyzed patients, 27 (14.8%) died, all of them due to transplant-related complications. TRM occurred more frequently in matched unrelated donor (MUD) transplant recipients vs. matched sibling donor (MSD) transplant recipients (p=0.02); in peripheral blood (PB) recipients vs. bone marrow (BM) recipients (p=0.004); and in patients receiving >5×10⁶/kg CD34+ cells (p<0.0001). OS differed significantly according to underlying disease comparing to other diagnoses. Lower survival was found in patients transplanted from MUD (p=0.02). OS was higher in patients receiving BM (p=0.001) and in those receiving ≤5×10⁶/kg CD34+ cells (p<0.001). Multivariate analysis showed lower probability of TRM in BM recipients (p=0.04). The probability of TRM was higher in SCID patients (p=0.02) and in patients receiving >5×10⁶/kg CD34+ cells (p=0.0001). CONCLUSIONS Underlying disease, stem cell source, and CD34+ dose higher than 5×10⁶/kg were the most important risk factors for TRM, and they all affected OS.

The effect of bone marrow graft composition on pediatric bone marrow transplantation outcomes

Hematopoietic stem cell graft cellular composition has been generally accepted to impact outcomes. Recent studies question this hypothesis. We conducted a single-center retrospective study of sixty-one pediatric BMT recipients for malignant (68%) and nonmalignant diseases (32%) examining effects of graft composition on engraftment, acute GVHD, chronic GVHD, and survival at day 100 and 1 year. Grafts contained a median of 3.63 x  0⁸ TNC/kg (range: 0.031-10.31 x 10⁸ TNC/kg) and 4.09 x 10⁶ CD34⁺ /kg (range: 0.76-24.15 x 10⁶ CD34⁺ /kg) with median neutrophil and platelet engraftment times of 17 and 29 days, respectively. A univariate analysis showed a trend for increasing TNC and increasing time to neutrophil engraftment HR: 0.875; CI: 0.075-1.001). Increasing CD34⁺ counts shortened time to platelet engraftment (HR: 1.085; CI: 1.015-1.161). No significant relationship was found between TNC, CD34⁺ , or CD3⁺ and acute or chronic GVHD. TNC or CD34⁺ did not affect day 100, 1-year survival, or 2-year survival. Increasing CD3⁺ counts demonstrated a negative trend on day 100 survival (HR: 1.108; CI: 1.001-1.036) but not 1-year survival or 2-year survival. These results add additional data questioning the effect of graft composition on outcomes in pediatric BMT patients with important ramifications for the management of donors.

Peripheral Blood or Bone Marrow Stem Cells? Practical Considerations in Hematopoietic Stem Cell Transplantation

Although peripheral blood stem cells (PBSC) have worldwide become the predominant source of progenitor cells for hematopoietic stem cell transplantation (HSCT), debate about their role compared with bone marrow (BM) has recently intensified, in large part based on the results of a multicenter Clinical Trials Network study which showed lower incidence of chronic graft-versus-host disease (cGVHD) and improved quality of life in recipients of myeloablative HLA-matched unrelated BM compared with PBSC transplants. However, in certain patient populations, PBSC may lead to improved clinical outcomes due to faster hematologic recovery, a lower risk of graft failure, and possibly a lower probability of relapse. This review will provide a comprehensive summary of studies comparing PBSC with BM as the graft source in terms of acute and chronic GVHD incidence, time to engraftment, and disease-free and overall survival probabilities after HLA-matched related and unrelated donor transplantation and haploidentical donor transplantation. Recommendations based on these studies regarding the use of PBSC versus BM for HSCT are offered.

[Preservation/congelation of hematopoietic stem cell grafts in a pediatric context: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

The Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) organized the 7th allogeneic hematopoietic stem cell transplantation clinical practices harmonization workshop series in September 2016 in Lille, France. The objective of our workshop is to provide a discussion on the conservation and congelation of hematopoietic stem cells in a pediatric setting as well as our recommendations for this technique.