Higher CD3+ and CD34+ cell doses in the graft increase the incidence of acute GVHD in children receiving BMT for thalassemia

Association between CD34+ and CD3+ T-cells in allogeneic grafts and acute graft-versus-host disease in children undergoing allogeneic hematopoietic stem cell transplantation: A single-center study

BACKGROUND

Acute graft-versus-host disease (aGVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We examined the association between the composition of the cell subsets present in allogeneic grafts (allografts) and the occurrence and severity of aGVHD in pediatric patients.

METHODS

We retrospectively analyzed 80 consecutive pediatric patients undergoing allo-HSCT at our center.

RESULTS

Both univariate and multivariate analyses showed that the number of CD34⁺ and CD3⁺ T-cells in allografts were the two highest risk factors associated with II-IV aGVHD. Using receiver operating characteristic analysis, the cutoff levels of the allo-HSCT cell doses were used to divide the recipients into low-dose and high-dose groups. The 100-day cumulative incidence of II-IV aGVHD in the high-dose CD34⁺ and CD3⁺ T-cells group was significantly higher than that of the low-dose group (CD34⁺: 57% vs. 29%, p = 0.009; CD3⁺: 63% vs. 18%, p < 0.001). No other clinical factors or cell subsets correlated with aGVHD incidence.

CONCLUSIONS

Our analysis indicates that the CD34⁺ and CD3⁺ T-cell numbers in the allografts could be the risk factors for the development of severe aGVHD (level II-IV). Further studies should aim to optimize the critical number of CD34⁺ and CD3⁺ T-cells to reduce the risk of severe aGVHD occurrence in pediatric patients.

Comparisons Between modified PTCY and G-CSF/ATG Regimens for Haploidentical Transplantation in Patients with Aplastic Anemia

BACKGROUND

Haploidentical transplantation has become an alternative treatment option for aplastic anemia patients without matched sibling donors or matched unrelated donors. Recently, the post-transplantation cyclophosphamide (PTCY) regimen and granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG) regimen have become the most common protocols used worldwide.

OBJECTIVE

We designed this retrospective study to compare the outcomes of patients receiving a modified post-transplantation cyclophosphamide (mPTCY) regimen versus the G-CSF/ATG regimen.

STUDY DESIGN

We retrospectively reviewed and analyzed the clinical data of 130 aplastic anemia patients who underwent haplo-HSCT and received the mPTCY regimen (n=55) or G-CSF/ATG regimen (n=75) between Jan 2013 and Jun 2021 across seven transplant centers.

RESULTS

Neutrophil engraftment was successful in all patients within 30 days in the G-CSF/ATG group. The cumulative neutrophil engraftment rate in the mPTCY group was 96.36% (95% CI, 94.57-97.57, P=0.010). The median time of neutrophil engraftment in the G-CSF/ATG group was 10 (7-28) days, which was more rapid than that observed in the mPTCY group (P <0.001). There were no significant differences in the incidence of graft versus host disease (GVHD) between the two groups. The cumulative incidence of II-IV acute GVHD was 18.40% (95% CI, 4.27-40.31) in the mPTCY group and 19.32% (95% CI, 5.86-38.58) in the G-CSF/ATG group, while the cumulative incidence of III-IV acute GVHD was 7.31% (95% CI, 0.09-37.48) in the mPTCY group and 7.57% (95% CI, 0.20-34.19) in the G-CSF/ATG group. Similarly, no significant difference was observed between the two groups in terms of overall survival (OS), failure-free survival (FFS), and GVHD relapse-free survival (GRFS). The 2-year OS, FFS and GRFS rates were 95.91% (95% CI, 84.59-98.96), 92.25% (95% CI, 80.59-97.03) and 86.68% (95% CI, 73.98-93.44), respectively, in the mPTCY group and 86.67% (95% CI, 76.64-92.59), 81.28% (95% CI, 70.45-88.46) and 77.20% (95% CI, 65.89-85.16), respectively, in the G-CSF/ATG group. The transplantation-related mortality (TRM) rate was significantly higher in the G-CSG/ATG group than in the mPTCY group (13.33% in the G-CSG/ATG group versus 1.96% in the mPTCY group, P=0.022). In multivariate analysis, female donors, a higher hematopoietic cell transplantation comorbidity index (HCT-CI) and III-IV aGVHD were associated with worse survival outcomes.

CONCLUSIONS

In conclusion, the mPTCY and G-CSF/ATG regimens led to similar outcomes in AA patients, but quicker engraftment was observed with the ATG/G-CSF regimen, and a lower incidence of TRM was observed with the mPTCY regimen.

Variable impact of graft CD3+ cell content on graft versus host disease in hematopoietic stem cell transplant recipients: Is the role of donor CD3+ cells overestimated?

Graft cellular composition is considered as a significant determinant of transplant outcome. Donor CD3⁺ cells were shown to have a significant association with the development of graft vs host disease (GvHD). The aim of this study was to investigate the impact of graft CD3⁺ cell content on transplant outcome, particularly in terms of GvHD and relapse. We retrospectively analysed the records of 515 allo-HCT recipients [median age: 37(15-71) years; male/female: 323/192]. The optimal threshold of infused CD3⁺ cell count for acute GvHD development was estimated to be 197.5 × 10⁶/kg (AUC: 0.572; 95 % CI: 0.513-0.631; p = 0.018) and 198.5 × 10⁶/kg (AUC: 0.6; 95 % CI: 0.520-0.679; p = 0.019) for the general population and reduced-intensity conditioning (RIC) subgroup, respectively. Acute GvHD was more frequent in low-CD3⁺ group in the whole study population, particularly in RIC transplants. The incidence of cytomegalovirus reactivation was higher in low-CD3⁺ group and neutrophil engraftment occured earlier in the same group of patients. Overall survival and non-relapse mortality were comparable between high and low-CD3⁺ groups. Age, ECOG performance status, hypogammaglobulinemia, chronic GvHD and post-transplant relapse were found to predict prognosis in multivariate analysis. By focusing mainly on donor T cells, the potential role of host immune cells in the early post-transplant milieu may have been underestimated. Drawing a more detailed profile of graft and host immune cells in the joint microenvironment may elucidate our way to a better understanding of GvHD pathogenesis. By this way a comprehensive pre-transplant risk assessment could be improved to generate more personalized approaches.

A concise review on factors influencing the hematopoietic stem cell transplantation main outcomes

BACKGROUND AND AIMS

As a curative procedure, hematopoietic stemcell transplantation (HSCT) is an approved treatment for many malignant orbenign hematologic and non-hematologic diseases. There are different outcomes of HSCT, as well as several parameters influencing these outcomes.

METHODS

We had searched scientific sources like Web ofScience and PubMed with a combination of keywords such as HSCT, engraftment,survival, outcomes, etc. Totally, 80 articles were included.

RESULTS

Here we have reviewed the effective factors onmain outcomes of HSCT including engraftment, survival, graft versus hostdisease, and Mobilization. Also, the prediction of hematological reconstitutionand some novel suggestions leading to better outcomes are reviewed.

CONCLUSION

The study will be applicable for improvedmanagement of autologous and allogeneic HSCT process to increase the procedureefficiency.

Different subsets of haematopoietic cells and immune cells in bone marrow between young and older donors

Young donors are reported to be associated with better transplant outcomes than older donors in allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the mechanism is still unclear. The current study compared the different subsets of haematopoietic stem cells (HSCs) and their progenitors as well as immune cells in bone marrow (BM) between young and older donors. The frequencies of HSCs, multipotent progenitors (MPPs) and myeloid progenitors, including common myeloid progenitors (CMPs) and megakaryocyte-erythroid progenitors (MEPs), were decreased, whereas those of lymphoid progenitors, including multi-potent lymphoid progenitors (MLPs) and common lymphoid progenitors (CLPs), were increased in the BM of young donors compared with in that of older donors. Lower reactive oxygen species (ROS) levels were observed in BM HSCs and six progenitor lines in young donors. Furthermore, young donors demonstrated higher frequencies of naive T cells and immune suppressor cells, such as alternative macrophages (M2) and lower frequencies of memory T cells and immune effectors, including T helper-1 and T cytotoxic-1 cells, in BM than older donors. Multivariate analysis demonstrated that donor age was independently correlated with BM HSC frequency. Although further validation is required, our results suggest that the differences in the frequency and immune differentiation potential of HSCs in BM between young donors and older donors may partly explain the different outcomes of allo-HSCT.

Monocyte subsets in bone marrow grafts may contribute to a low incidence of acute graft-vs-host disease for young donors

Young donors are associated with a lower cumulative incidence of acute graft‐vs‐host disease (aGVHD) after allogenic haematopoietic stem cell transplantation (allo‐HSCT) than old donors. Although grafts are harvested from healthy donors, it is unclear whether donor age is associated with aGVHD occurrence owing to its effect on cell compositions in grafts. Moreover, the differences in monocyte subsets in grafts between young and old donors and the association between monocyte subsets in bone marrow (BM) grafts and aGVHD remain to be elucidated. In the current study, non‐classical monocytes and the CD4⁺/CD8⁺ T cell ratio were remarkably decreased in BM grafts in donors <30 years old. Multivariate analysis further revealed that the level of non‐classical monocytes in BM grafts (≥0.31 × 10⁶/kg) was an independent risk factor for the occurrence of II‐IV aGVHD. In summary, our data indicate that non‐classical monocytes in BM grafts may help identify patients at high risk for aGVHD after allo‐HSCT. Although further validation is required, our results suggest that the low level of non‐classical monocytes and a low ratio of CD4⁺/CD8⁺ T cell in BM grafts may be correlated with the lower incidence of aGVHD in young donors.

High proportions of CD3+ T cells in grafts delayed lymphocyte recovery and reduced overall survival in haploidentical peripheral blood stem cell transplantation

T cells in grafts serve an important role in the pathogenesis of graft versus host disease (GVHD) and immune recovery during HLA matched allogeneic stem cell transplantation. However, the role of T cells in the haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) is yet to be determined. In the present study, the role of CD3⁺ T cells in grafts and impact on hematopoietic and immune recovery, cytomegalovirus (CMV) reactivation, GVHD, relapse, progress free survival and overall survival (OS) were evaluated and analyzed. A total of 30 patients who underwent haplo-PBSCT were included in the present study. CD3⁺ T cells accounted for a median of 23.1% (range 8-47.4%) with a median dose of 299.7x10⁶/kg (range 104-623.4). Patients were divided into two groups according to the CD3⁺ T cell count: Above the median (high T cell group) and below the median CD3⁺ T cell (low T cell group). No significant difference was identified between neutrophil and platelet recovery time between two groups (P>0.05). The mean lymphocyte recovery time of high T cell group and low T cell group were 107.07 days (95% CI 79.88-134.25), and 50.4 days (95% CI 41.42-59.38), respectively. The lymphocyte recovery time of high T cell group was higher that of low T cell group (P<0.05). No significant difference between CMV reactivation, chronic GVHD and primary disease relapse rates was observed between two groups (P>0.05). The cumulative incidence of grade II or above acute GVHD was higher in the high T groups compared with low T groups (P<0.05). The overall survival and progress free survival rates were higher in the low T cell group compared with the high T cell group (P<0.05). In conclusion, high levels of CD3⁺ T cells in the grafts were associated with delayed lymphocyte recovery and an increased risk of acute GVHD and decreased overall survival.

Emerging strategies for enhancing the homing of hematopoietic stem cells to the bone marrow after transplantation

Bone marrow failure is the primary cause of death after nuclear accidents or intentional exposure to high or low doses of ionizing radiation. Hematopoietic stem cell transplantation is the most potent treatment procedure for patients suffering from several hematopoietic malignancies arising after radiation injuries. Successful hematopoietic recovery after transplantation depends on efficient homing and subsequent engraftment of hematopoietic stem cells in specific niches within the bone marrow. It is a rapid and coordinated process in which circulating cells actively enter the bone marrow through the process known as transvascular migration, which involves the tightly regulated relay of events that finally leads to homing of cells in the bone marrow. Various adhesion molecules, chemokines, glycoproteins, integrins, present both on the surface of stem cells and sinusoidal endothelium plays a critical role in transvascular migration. But despite having an in-depth knowledge of homing and engraftment and the key events that regulate it, we are still not completely able to avoid graft failures and post-transplant mortalities. This deems it necessary to design a flawless plan for successful transplantation. Here, in this review, we will discuss the current clinical methods used to overcome graft failures and their flaws. We will also discuss, what are the new approaches developed in the past 10-12 years to selectively deliver the hematopoietic stem cells in the bone marrow by adopting proper targeting strategies that can help revolutionize the field of regenerative and translational medicine.

The CD34+ Cell Dose Matters in Hematopoietic Stem Cell Transplantation with Peripheral Blood Stem Cells from Sibling Donors

The effect of CD34⁺ cell dose in allogeneic hematopoietic stem cell transplantation (HSCT) on overall survival (OS) and incidence of acute and chronic graft-versus-host disease (GvHD) has not been established and few studies have been performed. Our single center analysis included 189 patients with hematological malignancies who received peripheral blood stem cell (PBSC) grafts from sibling donors. Myeloablative conditioning was used in 88 cases and 101 received reduced intensity conditioning. The median CD34⁺ cell dose was 5.6 × 10⁶/kg (0.6–17.0). In the multivariate analysis, a CD34 cell dose of 6–7 × 10⁶/kg was associated with better OS and lower transplant-related mortality (TRM), while a dose of <5 × 10⁶/kg led to increased relapse and reduced chronic GVHD (cGVHD). A high CD34 cell-dose (>6.5 × 10⁶/kg) correlated with less acute GVHD (aGVHD) II–IV. We conclude that the CD34 cell dose has an impact on the outcome of HSCT from sibling donor PBSCs.

Effect of Stem Cell Source and Dose on Allogeneic Hematopoietic Stem Cell Transplantation in Adult Patients with Idiopathic Aplastic Anemia: Data from the Korean Aplastic Anemia Trials

OBJECTIVE

We aimed to evaluate the effect of stem cell source and dose on the survival of various donor subgroups, such as matched sibling donor (MSDs) and alternative donors (ADs), upon bone marrow (BM) or peripheral blood stem cell (PBSC) infusion in aplastic anemia (AA).

METHODS

We retrospectively investigated the effects of stem cell source and dose on allogeneic hematopoietic stem cell transplantation (alloHSCT) in AA.

RESULTS

A total of 267 patients were included in this analysis. The BM-treated group showed an association with low incidence of any-grade acute graft versus host disease (GvHD) (p < 0.001). A higher stem cell dose was related with a low incidence of extensive chronic GvHD in MSDs (p = 0.025). Multivariate analysis for overall survival (OS) revealed that only age at alloHSCT <31 years (p = 0.010) and prior platelet transfusion <86 U (p = 0.046) in MSDs and higher stem cell dose (hazard ratio = 2.596, p = 0.045) in ADs were favorable prognostic factors.

CONCLUSION

PBSCs could be preferred in AD because high stem cell dose may be easily achieved to improve the OS at the expense of acute GvHD. However, BM stem cells are preferred in MSDs.

T Regulatory Cells in Donor Grafts May Predict the Severity of Acute Graft Versus Host Disease After Matched Sibling Donor Allogenic Peripheral Blood Stem Cell Transplantation

Acute graft-versus-host disease (aGVHD) and relapse are major issues for patients undergoing allogenic hematopoietic stem cell transplant (allo-HSCT). T-regulatory (Treg) cells in the donor graft are negatively correlated with the incidence of aGVHD without any impact on relapse. In this study to determine the association of Treg cells with aGVHD in allo-HSCT patients. Thirty-two patients with hematological disorders, who underwent allo-HSCT. Twenty-nine patients who achieved engraftment were enrolled in the study. Treg cells were quantified in donor graft by flowcytometry and were assessed for their association with aGVHD and other clinical outcomes. Fifteen of 29 patients developed aGVHD. According to the occurrence and severity of aGVHD, patients were divided into two groups: 20 (68.9%) patients with grade 0-I aGVHD and 9 (31.1%) patients with grade II-IV aGVHD. Treg cells/CD4 ratio was significantly higher in the grade 0-I aGVHD group than in grade II-IV aGVHD group, (p = 0.0002). We could not find the association of CD34 dose (p = 0.55) or CD3 dose (p = 0.57) with the severity of aGVHD. Higher Treg cells/CD4 ratio in donor graft was associated with less severe aGVHD. Though more studies are needed, Treg cells/CD4 ratio may be used as a predictive marker for severity of aGVHD in post allo-HSCT.

Bone marrow harvest from unrelated donors-up-to-date methodology

OBJECTIVES

Bone marrow harvesting is one of the essential sources of stem cells for hematopoietic stem cell transplantation. We describe here the current "up-to-date" standard of the bone marrow harvest in unrelated stem cell donors.

METHODS

We analyzed medical data of 187 unrelated hematopoietic stem cell donors who underwent bone marrow harvest without previous peripheral blood stem collection at the center between 2011 and 2015. The methodology of marrow collection includes multiple cells aimed at safety of the procedure, for example, educational movie, modified skin disinfection protocol, cell enumeration during the procedure, reduction of the contamination surfaces, and ongoing monitoring of the quality of work of the doctors.

RESULTS

The total nucleated cell count over 2×10⁸ per kg of recipient has been reached in 93.6% of harvests. All of the donors harvested more than 1×10⁸ per kg of the recipient. There were no donors who required transfusions or had serious adverse events during and after the harvest.

CONCLUSION

We describe here the current up-to-date standard of bone marrow harvest, which leads to excellent results in majority of donors without causing significant complications during the donation.

Influence of Age on Acute and Chronic GVHD in Children Undergoing HLA-Identical Sibling Bone Marrow Transplantation for Acute Leukemia: Implications for Prophylaxis

Relapse remains the major cause of mortality after hematopoietic cell transplantation (HCT) for pediatric acute leukemia. Previous research has suggested that reducing the intensity of calcineurin inhibitor-based graft-versus-host disease (GVHD) prophylaxis may be an effective strategy for abrogating the risk of relapse in pediatric patients undergoing matched sibling donor (MSD) HCT. We reasoned that the benefits of this strategy could be maximized by selectively applying it to those patients least likely to develop GVHD. We conducted a study of risk factors for GVHD, to risk-stratify patients based on age. Patients age <18 years with leukemia who received myeloablative, T cell-replete MSD bone marrow transplantation and calcineurin inhibitor-based GVHD prophylaxis between 2000 and 2013 and were entered into the Center for International Blood and Marrow Transplant Research registry were included. The cumulative incidence of grade II-IV acute GVHD (aGVHD) was 19%, that of grade II-IV aGVHD 7%, and that of chronic GVHD (cGVHD) was 16%. Compared with age 13 to 18 years, age 2 to 12 years was associated with a lower risk of grade II-IV aGVHD (hazard ratio [HR], .42; 95% confidence interval [CI], .26 to .70; P = .0008), grade II-IV aGVHD (HR, .24; 95% CI, .10 to .56; P = .001), and cGVHD (HR, .32; 95% CI, .19 to .54; P < .001). Compared with 2000-2004, the risk of grade II-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .36; 95% CI, .20 to .65; P = .0007) and in 2009-2013 (HR, .24; 95% CI. .11 to .53; P = .0004). Similarly, the risk of grade III-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .23; 95% CI, .08 to .65; P = .0056) and 2009-2013 (HR, .16; 95% CI, .04 to .67; P = .0126) compared with those doing so in 2000-2004. We conclude that aGVHD rates have decreased significantly over time, and that children age 2 to 12 years are at very low risk for aGVHD and cGVHD. These results should be validated in an independent analysis, because these patients with high-risk malignancies may be good candidates for trials of reduced GVHD prophylaxis.

Posterior Reversible Encephalopathy Syndrome after Hematopoietic Cell Transplantation in Children with Hemoglobinopathies

Posterior reversible encephalopathy syndrome (PRES) is a serious adverse event associated with calcineurin inhibitors used for graft-versus-host disease (GVHD) prophylaxis. We compared the incidence of PRES in children with thalassemia (n = 222, 1.4 to 17.8 years old) versus sickle cell disease (SCD; n = 59, 2 to 17 years old) who underwent hematopoietic cell transplantation from HLA-matched siblings or alternative donors and analyzed the risk factors for PRES. Overall, 31 children developed calcineurin inhibitor-related PRES (11%), including 30 patients with seizures and 1 patient without seizures. PRES incidence was significantly higher in SCD patients (22%; 95% confidence interval [CI], 10% to 32%) than in thalassemia patients (8%; 95% CI, 5% to 12%;P = .002). In multivariate analysis, factors associated with PRES were hypertension (hazard ratio [HR], 5.87; 95% CI, 2.57 to 13.43; P = .0001), SCD (HR, 2.49; 95% CI, 1.25 to 4.99; P = .009), and acute GVHD (HR 2.27; 95% CI, 1.06 to 4.85; P= .031). In the entire cohort overall survival (OS) was significantly higher in patients without versus with PRES (90% versus 77%; P = .02). In a subgroup analysis that including matched sibling transplants, OS and disease-free survival (DFS) were similar in thalassemia patients without PRES (92% and 88%, respectively) and with PRES (82% and 73%, respectively), whereas SCD patients with PRES had significantly lower OS (67%) and DFS (67%) than patients without PRES (94% and 94%, respectively; P = .008). Thus, SCD patients had a significantly higher incidence of PRES than thalassemia patients, and hypertension and GVHD were the 2 main risk factors for PRES in patients with hemoglobinopathies. Although PRES did not significantly influence survival in patients with thalassemia, patients with SCD had significantly lower survival after PRES.

Optimal Outcomes in Young Class 3 Patients With Thalassemia Undergoing HLA-Identical Sibling Bone Marrow Transplantation

BACKGROUND

Bone marrow transplantation (BMT) for class 3 patients with thalassemia is challenging due to high rates of graft rejection and transplant-related mortality. Since the first studies of BMT in the late 1980s, a number of conditioning regimens have been designed to improve outcomes, but with suboptimal results. Here we report the outcome of transplantation in class 3 patients using a modified protocol.

METHODS

Sixty-three patients between 5 and 16.7 years of age with class 3 thalassemia received HLA-matched sibling BMT following either the original protocol (26 patients) or the modified protocol (37 patients). Both regimens comprised preconditioning cytoreduction with hydroxyurea and azathioprine starting at -45 days pretransplant, and fludarabine from days -16 to -12. Conditioning was performed with busulfan and cyclophosphamide (original protocol) or with busulfan, thiotepa, and cyclophosphamide (modified protocol).

RESULTS

The 2 groups showed similar patient demographics. At day 0, the degree of cytoreduction (lymphopenia, neuthropenia, and thrombocytopenia) achieved by the modified protocol was greater than the original protocol. The incidence of graft failure/rejection was significantly higher in the original group (15%; 95% confidence interval [95% CI], 5-32%) compared with the modified group (0%) (P = 0.014). The respective 5-year thalassemia-free survival rates were 73% (95% CI, 51-86%) and 92% (95% CI, 77-97%) (P = 0.047). Both groups showed similar incidences of grades II to IV acute graft-versus host disease. Modified protocol did not increase nonhematological toxicity or infectious complications.

CONCLUSIONS

The modified treatment protocol effectively and safely prevented graft failure/rejection and significantly increased thalassemia-free survival of class 3 patients with thalassemia.

Haematopoietic stem cell transplantation for sickle cell disease - current practice and new approaches

Sickle cell disease is an inherited disorder that affects over 5 million people worldwide. Current maintenance therapy has been successful in reducing complications and enhancing life expectancy; yet subclinical complications persist. To date, allogeneic haematopoietic stem cell transplant (HSCT) remains the only available curative therapy for sickle cell disease. With declining incidences of rejection and transplant- related mortality, disease-free survival after human leucocyte antigen-identical sibling transplant exceeds 90%. However, the majority of individuals with sickle cell disease do not have an human leucocyte antigen (HLA)-identical sibling; therefore, research is expanding to focus on new approaches to alternative donor transplant. Advances in supportive care and conditioning regimens have led to expansion of the pool of donors to unrelated donors and haploidentical donors. Challenges remain in improving the safety and efficacy of HSCT from alternate donors. Early results from gene therapy may provide another curative option in patients with sickle cell disease. These approaches show early promise, but larger, longitudinal studies are needed to better determine the optimal clinical circumstances for transplant in sickle cell disease.

Infectious complications following allogeneic stem cell transplantation by using anti-thymocyte globulin-based myeloablative conditioning regimens in children with hemoglobinopathies

BACKGROUND

Anti-thymocyte globulin (ATG) has been used to prevent graft failure/rejection in the setting of allogeneic stem cell transplantation (allo-SCT) for hemoglobinopathies; however, epidemiology data for transplant-related infections in this population are scarce.

METHOD

We retrospectively analyzed the epidemiology of bacterial, fungal, viral, and parasitic infections in a cohort of 105 children and adolescents with β-thalassemia (n = 100) or sickle cell disease (n = 5) who underwent allo-SCT using human leukocyte antigen (HLA)-identical sibling (n = 96) or HLA-compatible unrelated donors (n = 9) in a single institution. All patients received an ATG-based conditioning regimen.

RESULTS

The cumulative incidence of cytomegalovirus (CMV) viremia was 45.7% (95% confidence interval [CI] 33-55%), developing at a median of 48 (range 12-142) days without evidence of overt CMV disease. Herpes zoster developed in 8 patients at a median of 12 months post transplant, while 10 patients presented with late onset hemorrhagic cystitis at a median of 35 days post transplant. The cumulative incidence of bacteremia was 17.1% (95% CI 10.6-25%), occurring at a median of 74 (range 24-110) days. No patient developed probable or definite invasive fungal infection. Four deaths were recorded; 2 of them were attributed to infections (toxoplasmosis and Pneumocystis jirovecii pneumonia, respectively).

CONCLUSION

The rate of infections after allo-SCT, using an ATG-containing preparative regimen, in our population of pediatric patients with hemoglobinopathies is comparable to that reported elsewhere with the use of non-ATG containing regimens.

Effect of Total Nucleated and CD34(+) Cell Dose on Outcome after Allogeneic Hematopoietic Stem Cell Transplantation

During more recent years only few studies have analyzed the effect of total nucleated cell (TNC) and CD34(+) cell dose in allogeneic hematopoietic stem cell transplantation (HSCT). A single-center analysis included 544 patients, 227 with a sibling donor and 317 with an unrelated donor. Most patients (n = 292) were treated with myeloablative conditioning, whereas the remaining patients (n = 252) received reduced-intensity conditioning. Bone marrow (BM) (n = 121) and peripheral blood stem cell (PBSC) grafts (n = 423) were analyzed separately. Median TNC and CD34(+) cell dose was 3.2 × 10(8)/kg versus 11.6 × 10(8)/kg in BM and 3.9 × 10(6)/kg versus 8.1 × 10(6)/kg in PBSC. In the BM group we found a higher TNC and CD34(+) cell dose was associated with a faster neutrophil engraftment (P < .001 and P = .02). In the PBSC group we found patients given a very high (≥11 × 10(6)/kg) CD34(+) cell dose had decreased rates of survival (P = .001) and increased relapse (P = .02). A high CD34(+) cell dose correlated with faster platelet engraftment (P < .01). In HSCT using PBSCs, the CD34(+) cell doses should be kept below 11 × 10(6)/kg but over 2.5 × 10(6)/kg.

Risk Factors, Pattern and Clinical Outcome of Acute Graft Versus Host Disease in Acute Leukemia Patients Undergoing Allogeneic Stem Cell Transplant

We sought to determine risk factors, pattern and outcome of acute graft versus host disease (aGVHD) in seventy-seven acute leukemia patients who underwent allogeneic stem cell transplant at our centre from January 2008 to March 2013. GVHD prophylaxis with cyclosporine-methotrexate or cyclosporine-mycophenolate mofetil was used. Patients were divided in 2 groups, grade II-IV aGVHD (group A) and grade 0-I aGVHD (group B). Incidence of any grade and grade II-IV aGVHD was 44 and 18 %, respectively. The most common site of aGVHD was gastro-intestinal tract (65 %) followed by skin (35 %). Higher total nucleated cell (TNC) dose infused was associated with increased incidence of grade II-IV aGVHD. Incidence of relapse and incidence of slippage of chimerism was 21 and 36 % in group A while 37 and 27 % in group B respectively. Transplant related mortality (TRM) was 21 % in group A and 13 % in group B. Probability of OS and RFS at 4 years was 63 and 34 % in group A compared with 40 and 38 % in group B, respectively. We conclude that higher TNC dose infused is a risk factor for grade II-IV aGVHD with gut being the commonest site. Grade II-IV aGVHD did not have a significant impact on incidence of relapse, TRM and OS.

Impact of CD34+ cell dose in children who receive unrelated PBSCT with in vivo T-cell depletion for hematologic malignancies

PBSCs are increasingly being chosen as the mode of donation among unrelated donors. Pediatric patients, in particular, may receive very high CD34(+) and CD3(+) doses during unrelated PBSCT. In this work, we analyzed survival and GVHD outcomes in a cohort of 81 children who received unrelated PBSCT with uniform antithymocyte globulin (ATG)-based in vivo T-cell depletion for treatment of hematologic malignancy, with emphasis on the impact of cell dose on transplant outcomes. EFS was 61.5±5.6%, with higher CD34(+) dose (>10.0 × 10(6)/kg) and lower patient risk status predicting improved survival in multivariate study. Cumulative incidence of relapse was 30.2±5.2%; a low CD34(+) dose was the only significant factor for relapse. Neither CD34(+) nor CD3(+) dose was a significant determinant of acute or chronic GVHD. Importance of CD34(+) dose was reaffirmed in a subcohort of younger patients who received greater median cell doses than the overall cohort. In summary, for children who received unrelated PBSCT with ATG-based T-cell depletion for treatment of hematologic malignancy, the CD34(+) dose was the most important factor for relapse and EFS, and neither the CD34(+) nor the CD3(+) dose influenced incidence of acute or chronic GVHD.

Combined umbilical cord blood and bone marrow from HLA-identical sibling donors for hematopoietic stem cell transplantation in children with hemoglobinopathies

BACKGROUND

It is well established that umbilical cord blood and bone marrow are biologically different stem cell sources.

PATIENTS AND METHODS

We analyzed the feasibility and outcome of hematopoietic stem cell transplantation (HSCT) in 13 children (median age 5.9 years) with hemoglobinopathies after the co- infusion of cord blood (CB) and bone marrow (BM) from the same human leucocyte antigen (HLA) identical sibling donor. We also compared outcomes of children with co-transplantation to outcomes in children with hemoglobinopathies who had received a BM (n = 21) or CB (n = 22) transplant alone.

RESULTS

Compared to CB transplant (CBT) recipients, the co-transplant group had more rapid neutrophil (17 vs. 25 days, P = 0.013) and platelet (29 vs. 48 days, P = 0.009) recovery and less transplant related mortality. Patients who received a co-transplant had a lower incidence of ≥ grade II acute (0% vs. 26.3%) and chronic (0% vs. 21%) graft versus host disease (GVHD) compared to BM transplant (BMT) recipients (P = 0.055 and 0.045, respectively). With a median follow-up of >60 months in each treatment group, the 5-year probability of event free survival (EFS) was 100% in the co-transplant group, 90% after BMT and 86% after CBT (P = 0.42).

CONCLUSION

Co-transplantation of CB and BM from HLA-identical sibling donors appears to be a feasible and effective strategy to further optimize outcomes of HSCT for hemoglobinopathies.

Bone marrow transplantation for thalassemia from alternative related donors: improved outcomes with a new approach

Bone marrow transplantation (BMT) performance can be limited by a lack of ideal donors, and the role of alternative donor hematopoietic cell transplantation in thalassemia is not well established. Here we used a new treatment protocol (Pc 26.1) in 16 thalassemia patients to perform BMT using phenotypically HLA-identical or 1-antigen-mismatched relatives (related donors [RDs]). We compared these results with HLA-matched sibling (matched sibling donors [MSDs]) BMT in 66 patients. The entire RD group and 88% of MSD group had sustained engraftment. Rejection incidence was 0% in the RD and 12% (95% confidence interval [95% CI], 6%-21%) in MSD groups (P = .15), with respective thalassemia-free survival probabilities of 94% (95% CI, 63%-99%) and 82% (95% CI, 70%-89%) (P = .24). Transplant-related mortality was 6% (95% CI, 1%-26%) in the RD group and 8% (95% CI, 3%-16%) in the MSD group (P = .83). The intensified new protocol was not associated with increased nonhematologic toxicity. The present data show that the Pc 26.1 preparative regimen allows thalassemia patients to safely undergo BMT from RDs who are not HLA-matched siblings, with transplant outcomes similar to patients with MSD grafts.

Stem cell source-dependent reconstitution of FOXP3+ T cells after pediatric SCT and the association with allo-reactive disease

In adult patients, regulatory CD4+FOXP3+ T cells are suggested to have a role in the control of allo-reactive disease after hematopoietic SCT (HSCT). We compared CD4+FOXP3+ T-cell reconstitution after unrelated cord blood (UCB), matched unrelated donor (MUD) and matched sibling donor (MSD) HSCT in children, starting as early as 1 week after transplantation, and analyzed the association with allo-reactive disease. A total of 30 children were included who underwent a myeloablative-conditioning regimen followed by UCB (12/30), MUD (7/30) or MSD (11/30) HSCT. These three patient groups showed significant differences in FOXP3+ T-cell reconstitution pattern. Early after UCB and MSD, but not after MUD, HSCT a peak in FOXP3+ T cells was observed. There were significant differences in activation status and Ki67 expression of the FOXP3+ T cells after UCB and MSD, respectively. FOXP3+ T-cell proportions early after HSCT and in the graft were inversely correlated with allo-reactivity. This study indicates that FOXP3 reconstitution after HSCT is dependent on the type of graft used. Furthermore, in children evaluation of FOXP3+ T-cell numbers early after HSCT and in the graft may be used to judge the risk of developing allo-reactivity after HSCT.