Allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning regimen in children: a single-center experience

Busulfan-Based and Treosulfan-Based Myeloablative Conditioning for Allogeneic Transplantation in Children with Thalassemia Major: a Single-Center Experience From Southern Turkey

OBJECTIVES

Allogeneic hematopoietic stem cell transplant is the only curative treatment for patients with transfusion-dependent thalassemia major. In recent years, a number of novel approaches have improved patient outcomes and quality of life by minimizing the toxicity of conditioning regimens. The objective of this study was to compare the role of treosulfan- and busulfan-based conditioning in transfusion-dependent thalassemia.

MATERIALS AND METHODS

Data were collected retrospectively on 121 children with beta thalassemia major who underwent hematopoietic stem cell transplant using treosulfan-based (n = 37) or busulfan-based (n = 84) conditioning regimens between 2012 and 2022.

RESULTS

Two-year overall survival was 87.5% in the busulfan-based conditioning group and 91.1% in the treosulfan-based conditioning group.The group given the busulfan regimen compared with treosulfan regimen had significantly increased number of side effects (58.3% vs 21.6%, respectively; P < .001). When the busulfan-based regimen by level was evaluated, we observed no significant differences between the frequency of side effects according to drug serum levels. In addition, no significant differences were shown between the 2 regimen groups for cumulative incidence of acute and chronic graft-versus-host disease.

CONCLUSIONS

The safety and effectiveness of a treosulfan-based myeloablative conditioning regimen has been confirmed by ourretrospective investigation of pediatric patients with beta thalassemia.

Autologous or allogeneic hematopoietic stem cells transplantation combined with high-dose chemotherapy for refractory neuroblastoma: A protocol for systematic review and meta-analysis

BACKGROUND

Neuroblastoma is a common solid malignant tumor in children. Despite the development of new treatment options, the prognosis of high-risk neuroblastoma patients is still poor. High-dose chemotherapy and hematopoietic stem cell (HSC) transplantation might improve survival of patients with refractory neuroblastoma. In this study, we aimed to summarize the efficacy of autologous or allogeneic HSC transplantation combined with high-dose chemotherapy for patients with refractory neuroblastoma through the meta-analysis.

METHODS AND ANALYSIS

Relevant clinical trials of autologous or allogeneic HSC transplantation for the treatment refractory neuroblastoma patients will be searched in Web of Science, Cochrane Library, PubMed, Google Scholar, Embase, Medline, China National Knowledge Infrastructure, China Scientific Journal Database, Chinese Biomedical Literature Database and Wanfang Database from their inception to December 2020. Two researchers will perform data extraction and risk of bias assessment independently. The clinical outcomes including tumor response, overall survival, event-free survival (EFS), quality of life (QoL) and adverse events, were systematically evaluated by using Review Manager 5.3 and Stata 14.0 statistical software.

RESULTS

The results of this study will provide high-quality evidence for the effect of autologous or allogeneic HSC transplantation combined with high-dose chemotherapy on tumor response, survival, and QoL in patients with refractory neuroblastoma.

CONCLUSIONS

The conclusions of this meta-analysis will be published in a peer-reviewed journal, and provide more evidence-based guidance in clinical practice.

Acute toxicity and outcome among pediatric allogeneic hematopoietic transplant patients conditioned with treosulfan-based regimens

Treosulfan-based regimens constitute a feasible and increasingly used, but still myeloablative, conditioning in pediatric allogeneic hematopoietic stem cell transplantation (HSCT). We retrospectively analyzed the acute toxicity and outcome of all consecutive (2004-2015) pediatric HSCT patients prepared for HSCT with treosulfan in a single-center setting. We included HSCTs performed for both nonmalignant (n = 23) and malignant diseases (n = 11). The controls were patients with nonmalignant diseases or hematological malignancies conditioned with cyclophosphamide (Cy)-total body irradiation (TBI)-based (39 patients) or busulfan-based regimens (11 patients). The major toxicities of the treosulfan-based regimens were limited to oral mucosa and skin. 50% of the patients needed IV morphine for severe mucositis compared to 31% in patients conditioned with Cy-TBI (P = 0.02). Other toxicities were rare. The disease-free survival (DFS) of patients transplanted for nonmalignant disorders was 88.9 ± 7.5% at 2 years. The event-free survival (EFS) at 2 years in this small cohort for those with a malignant disease and a treosulfan-based conditioning was 54.5 ± 1.5%. We conclude that a treosulfan-based conditioning regimen gives excellent DFS in pediatric HSCT performed for a nonmalignant disorder but with substantial mucosal toxicity. In a malignant disorder a treosulfan-based regimen looks promising but larger, preferably randomized, studies are needed to prove efficacy.

Neuroblastoma

Neuroblastoma is one of the most common solid tumors in children and has a diverse clinical behavior that largely depends on the tumor biology. Neuroblastoma exhibits unique features, such as early age of onset, high frequency of metastatic disease at diagnosis in patients over 1 year of age and the tendency for spontaneous regression of tumors in infants. The high-risk tumors frequently have amplification of the MYCN oncogene as well as segmental chromosome alterations with poor survival. Recent advanced genomic sequencing technology has revealed that mutation of ALK, which is present in ~10% of primary tumors, often causes familial neuroblastoma with germline mutation. However, the frequency of gene mutations is relatively small and other aberrations, such as epigenetic abnormalities, have also been proposed. The risk-stratified therapy was introduced by the Japan Neuroblastoma Study Group (JNBSG), which is now moving to the Neuroblastoma Committee of Japan Children's Cancer Group (JCCG). Several clinical studies have facilitated the reduction of therapy for children with low-risk neuroblastoma disease and the significant improvement of cure rates for patients with intermediate-risk as well as high-risk disease. Therapy for patients with high-risk disease includes intensive induction chemotherapy and myeloablative chemotherapy, followed by the treatment of minimal residual disease using differentiation therapy and immunotherapy. The JCCG aims for better cures and long-term quality of life for children with cancer by facilitating new approaches targeting novel driver proteins, genetic pathways and the tumor microenvironment.

Improvement of overall survival after allogeneic hematopoietic stem cell transplantation for children and adolescents: a three-decade experience of a single institution

Allogeneic stem cell transplantation (allo-SCT) has become an essential component of the treatment for a variety of diseases in pediatric patients. During the past decades, advances in the transplant technology, availability of hematopoietic stem cells and supportive care not only have resulted in improved outcomes, but also have expanded the transplant options. However, these features have been studied mainly in adult populations. This investigation analyzed changes in patient profile, transplantation, graft characteristics and outcome among 250 children and adolescent patients who received allo-SCT in a single center between 1983 and 2010. In the 2000-2010, compared with the 1983-1999 period, a significantly higher 5-year overall survival (64% versus 52%, P=0.03) was observed together with a significant decrease of non-relapse mortality (27% versus 9%, P=0.0002). The progression-free survival was comparable between the two periods (49% versus 57%; P=0.17). The 5-year cumulative incidence of relapse was 24% between 1983 and 1999, and 34% between 2000 and 2010 (P=0.08). Major advances in supportive care practice have been made over the past decade, resulting in a significant survival benefit for the pediatric population undergoing allo-SCT. However, post-transplant relapse remains the leading cause of failure of this therapeutic approach, and preventing relapse represents a major challenge today.

In vivo T-cell depletion using alemtuzumab in family and unrelated donor transplantation for pediatric non-malignant disease achieves engraftment with low incidence of graft vs. host disease

In vivo T-cell depletion, using alemtuzumab therapy prior to SCT, can reduce the incidence of GVHD. This treatment has a potential to delay immune reconstitution resulting in increased morbidity due to viral illnesses. We retrospectively analyzed data on all pediatric patients with non-malignant disorders who received alemtuzumab-based conditioning regimens in our center over the last 10 yr (n = 91). Our data show an OS of 91.2%. The incidence of acute (grade 2-4) GVHD was 18.7% and that of chronic GVHD 5.5%. Viremia due to adenovirus, EBV and CMV was seen in 19.8%, 64.8% and 39.6% patients, respectively, with only two deaths attributed to viral infection (adenovirus). Chimerism level at three month was predictive of graft outcome. Nine patients, who had graft failure after first SCT, were salvaged with a second SCT using RIC and same donor (if available). Based on these results, we conclude that the use of in vivo T-cell depletion is safe, achieves good chimerism and does not lead to increased morbidity and mortality due to viral infections. It is associated with a reduced incidence of chronic GVHD.

Reduced-toxicity myeloablative conditioning consisting of 8-Gy total body irradiation, cyclophosphamide and fludarabine for pediatric hematological malignancies

Conventional myeloablative conditioning (MAC) regimens often cause severe regimen-related toxicity (RRT). Furthermore, many patients suffer from poor quality of life in accordance with the increase in long-term survivors. We therefore devised a reduced-toxicity myeloablative conditioning (RTMAC) regimen consisting of 8-Gy total body irradiation (TBI), fludarabine (FLU) and cyclophosphamide (CY) for pediatric hematological malignancies. A retrospective single-center analysis was performed on patients with leukemia or myelodysplastic syndrome (MDS), aged ≤20 years, who had received an 8-Gy TBI/FLU/CY RTMAC regimen followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Thirty-one patients underwent first allo-HSCT after an RTMAC regimen. The diagnoses were acute lymphoblastic leukemia (n = 11), acute myeloid leukemia (n = 13), MDS (n = 4), juvenile myelomonocytic leukemia (n = 1) and acute leukemias of ambiguous lineage (n = 2). While 3 patients showed early hematological relapse, the remaining 28 patients achieved engraftments. None of the patients developed grade 4 or 5 toxicities during the study period. The 5-year overall survival and relapse-free survival were 80% [95% confidence interval: CI, 61-91%] and 71% [95% CI, 52-84%], respectively. Our RTMAC regimen would be less toxic and offers a high probability of survival for children with hematological malignancies.

Allogeneic hematopoietic cell transplantation for neuroblastoma: the CIBMTR experience

While the role of auto-HCT is well established in neuroblastoma, the role of allo-HCT is controversial. The CIBMTR conducted a retrospective review of 143 allo-HCT for NBL reported in 1990-2007. Patients were categorized into two different groups: those who had not (Group 1) and had (Group 2) undergone a prior auto HCT (n=46 and 97, respectively). One-year and five-year overall survival (OS) were 59% and 29% for Group 1 and 50% and 7% for Group 2. Amongst donor types, disease free survival (DFS) and OS were significantly lower for unrelated transplants at 1 and 3 years but not 5 years post-HCT. Patients in complete response (CR) or very good partial response (VGPR) at transplant had lower relapse rates and better DFS and OS, compared to those not in CR or VGPR. Our analysis indicates that allo-HCT can cure some neuroblastoma patients, with lower relapse rates and improved survival in patients without a history of prior auto-HCT as compared to those patients who had previously undergone auto-HCT. Although the data do not address why either strategy was chosen for patients, allo-HCT after a prior auto-HCT appears to offer minimal benefit. Disease recurrence remains the most common cause of treatment failure.