Haploidentical stem cell transplant with post-transplantation cyclophosphamide and mini-dose methotrexate in children

Improving Outcomes with Haploidentical Stem Cell Transplantation [HaploSCT] in Children Using Post-transplant Cyclophosphamide: a Single Center Experience

Haplo-identical stem cell transplant using post-transplant cyclophosphamide is increasingly being used in children without a matched sibling donor. Between 2010 and June 2021, 127 children underwent 138 transplants with a median age of 7.1 years for malignant and non-malignant disorders. Conditioning regimens included both myeloablative and reduced intensity regimens with peripheral blood stem cells as the main graft source. Engraftment occurred in 113 [81.9%] at a median of 16 days [range: 10-32] with primary graft failure in 10.2%. Cumulative incidence of grade II-IV acute graft versus host disease (GVHD) was 49.5% and chronic GVHD in 40.7%. Majority [92.7%] had at least one infection with 31% incidence of bacterial infection, 76% incidence of viral and 16% incidence of fungal infection. The 2-year overall survival (OS) is 54.9 ± 4.6% with a lower survival among young children aged 0-5 years [28.2 ± 6.4%] compared to 5-10 years [71.3 ± 6.8%] and 11-15 years [55.7 ± 8.8%] [p = 0.032]. 2-year OS has gradually improved from 25.0 ± 2.1% for 2010-2013 to 47.5 ± 6.2% for 2014-2017 and 67.1 ± 6.6% for 2018-2021 [p = 0.049]. On multivariate analysis, bacterial infection [p = 0.017], invasive fungal disease [p = 0.002] and graft failure [p = 0.029] negatively impacted overall survival. Haplo-identical SCT with post-transplant cyclophosphamide is a reasonable option for children who do not have a matched sibling donor. Strategies to reduce graft failure, infection related mortality and GVHD needs to be explored.

Human Leukocyte Antigen-Haploidentical Haematopoietic Stem Cell Transplantation Using Post-Transplant Cyclophosphamide for Paediatric Haematological Malignancies

The use of human leukocyte antigen (HLA)-haploidentical haematopoietic stem cell transplantation (HSCT) with post-transplant cyclophosphamide (PTCY), which markedly reduces the risk of graft-versus-host disease, has rapidly increased worldwide, even in children. It was initially developed for post-transplant relapse or non-remission at transplant for patients with high-risk haematologic malignancies. However, this strategy is currently used more frequently for standard-risk, transplant-eligible paediatric haematological malignancies. It has recently been recognised in adults that the transplant outcomes after PTCY-based HLA-haploidentical HSCT are comparable with those achieved after HLA-matched HSCT. Therefore, even in children, parental donors who are HLA-haploidentical donors and cord blood are currently considered the next donor candidates when an HLA-matched related or unrelated donor is unavailable. This review addresses the current status of the use of haplo-HSCT with PTCY for paediatric haematologic malignancies and future directions for donor selection (sex, age, ABO blood type, and HLA disparity), donor source, the dose of infused CD34+ cells, optimal conditioning, the concomitant graft-versus-host disease prophylaxis other than PTCY, and the pharmacokinetic study of CY and CY metabolites. These aspects present key solutions for further improvements in the outcomes of haplo-HSCT with PTCY for paediatric haematological malignancies.

The MAGIC algorithm probability (MAP)-guided preemptive therapy of acute graft versus host disease with methylprednisolone: A randomized controlled trial

Acute graft versus host disease (aGvHD) is a severe complication that arises in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) and remains the primary cause of nonrelapse mortality (NRM). The MAGIC algorithm probability (MAP) has been proposed to identify patients at intermediate and high risk of developing aGvHD. The levels of suppression of tumorigenicity 2 (ST2) and regenerating islet-derived 3α (Reg3α) were assessed, and MAP was calculated on days 7, 14, 21, and 28 after allo-HSCT. Based on the MAP results, patients were classified into low-, intermediate-, or high-risk groups for the development of aGvHD. Random assignment was performed to allocate intermediate- or high-risk patients to receive preemptive therapy with methylprednisolone or not. The 100-day cumulative incidences of grade 2 or higher (35.5% ± 8.6%) and grade 3 or higher (12.9% ± 6.0%) aGvHD in the methylprednisolone group were significantly lower than those in the control group (66.7% ± 7.9%, p = .01; 42.9% ± 8.4%, p = .01), and similar to those observed in the low-risk group (31.7% ± 7.3%, p = .75; 2.4% ± 2.4%, p = .08). The 6-month cumulative incidences of NRM were 14.1% ± 6.6%, 22.7% ± 7.1%, and 2.4% ± 2.4% in the methylprednisolone, control, and low-risk groups, respectively, with no significant difference between the methylprednisolone and control groups (p = .29). Methylprednisolone did not increase infections (p = .34). The 100-day cumulative incidences of cytomegalovirus (CMV) reactivation were 67.7% ± 8.4%, 65.6% ± 8.4%, and 46.3% ± 7.8% (p = .08), and those of grade 2 or higher hemorrhagic cystitis were 29.0% ± 8.2%, 45.2% ± 8.9% and 22.0% ± 6.5% (p = .11) in the methylprednisolone, control, and low-risk groups, respectively. MAP-guided preemptive therapy for aGvHD is promising. The long-term efficacy and safety remain to be investigated.

Haploidentical transplant for paediatric patients with severe thalassaemia using post-transplant cyclophosphamide and methotrexate: A prospectively registered multicentre trial from the Bone Marrow Failure Working Group of Hunan Province, China

Haploidentical transplantation strategies for patients with transfusion-dependent thalassaemia (TD-TM) remain to be investigated. In this study, 54 paediatric patients with TD-TM were treated with a novel approach using post-transplant cyclophosphamide (PTCy) and low-dose methotrexate (LD-MTX), following a myeloablative regimen. The incidence of neutrophil and platelet engraftment was 96.3% ± 2.6% and 94.4% ± 3.1% respectively. The cumulative incidence of grades II-III acute graft-versus-host disease (GVHD) was 13.8% ± 4.8% at 100 days. At three years, the cumulative incidence of chronic GVHD was 28.5% ± 8.5%. With a median follow-up of 520 days (132-1325 days), the overall survival (OS) and event-free survival (EFS) were 98.1% ± 1.8% and 90.7% ± 3.9% respectively. Compared with the low-dose cyclophosphamide (CTX) conditioning regimen (120 mg/kg), the high-CTX regimen (200 mg/kg) achieved a higher incidence of stable engraftment (100% vs 66.7% ± 15.7%, p = 0.003), a comparable incidence of grades II-III acute GVHD, a lower incidence of chronic GVHD (20.2% ± 8.3% vs 66.6% ± 19.2%, p = 0.011), and better overall survival (100% vs 88.9% ± 10.5%, p = 0.025) as well as EFS (95.6% ± 3.1% vs 66.7% ± 15.7%, p = 0.008). Our results using unmanipulated haploidentical grafts and PTCy with LD-MTX in TD-TM are encouraging. (chictr.org.cn ChiCTR1800017969).

Fanconi anemia and haploidentical stem cell transplantation

BACKGROUND

Fanconi anemia is a congenital disorder belonging to bone marrow syndromes, with a risk of developing malignancy. Hematopoietic stem cell transplantation is the only curative treatment in these cases. Here, we aimed to report our clinical experience in pediatric patients with Fanconi anemia treated with haploidentical stem cell transplantation and post-transplant cyclophosphamide, an alternative strategy.

METHODS

We performed a case report based on clinical records of two patients who signed the informed consent form and were treated at Fundación Valle del Lili.

RESULT

Two pediatric patients, both with reduced-intensity conditioning, prophylaxis for acute graft-versus-host disease with post-transplant cyclophosphamide. They achieved primary neutrophil/platelets engraftment, and 100% chimerism. Had grade I or II graft-versus-host disease resolved? Currently are alive and in complete remission.

CONCLUSIONS

The use of mismatched related donors for haploidentical stem cell transplantation and post-transplant cyclophosphamide might be a promising option, and well-tolerated in pediatric patients. Serial chimerism can be useful during follow-up.

Risk factors and incidence of cytomegalovirus viremia and disease in pediatric patients with allogeneic hematopoietic stem cell transplantation: An 8-year single-center experience in Latin America

BACKGROUND

Cytomegalovirus infection represents a significant cause of morbidity and mortality after hematopoietic stem cell transplantation. This study aimed to evaluate the incidence of viremia and disease due to cytomegalovirus and the risk factors in pediatric patients with hematopoietic stem cell transplantation in our institution.

METHODS

This was a retrospective cohort of patients under 19 years of age who underwent allogeneic hematopoietic stem cell transplantation due to any indication between 2012 and 2019. The analysis included the diagnosis of cytomegalovirus viremia or disease during post-transplant follow-up, evaluation of risk factors, and outcomes. The statistical analysis included univariate and multivariate analyses, and the cumulative incidence of cytomegalovirus viremia was determined by the Kaplan-Meier method using STATA 14 statistical software.

RESULTS

A total of 182 transplants were included. At 100 days, the cumulative incidence of cytomegalovirus viremia was 70.5%, and that of cytomegalovirus disease was 4.7%. Overall survival at 2 years was 74%, and event-free survival was 64%. The remaining demographic characteristics were not predictors of infection. There was no association between viremia and relapse or survival of the patients. Higher mortality was noted in cytomegalovirus disease.

CONCLUSIONS

During the study period, the incidence of cytomegalovirus disease was similar to that of other pediatric reports, but the incidence of viremia was higher. Pre-emptive therapy has diminished disease rates and death due to infection. Viral load cutoff points should be standardized to guide treatment and avoid myelotoxicity.

Prophylaxis for invasive fungal infection in pediatric patients with allogeneic hematopoietic stem cell transplantation

Background

Antifungal prophylaxis is recommended for hematopoietic stem cell transplantation (HSCT) to decrease the incidence of invasive fungal infections (IFI). This study aimed to compare the two groups of antifungal prophylaxis in pediatric patients undergoing allogeneic HSCT.

Methods

This observational, analytic, retrospective cohort study compared the incidence of IFI with antifungal prophylaxis with voriconazole vs. other antifungals in the first 100 days after allogeneic HSCT in patients aged <18 years between 2012 and 2018. The statistical analysis included univariate and multivariate analyses and determination of the cumulative incidence of invasive fungal infection by the Kaplan‒Meier method using STATA 14 statistical software.

Results

A total of 139 allogeneic HSCT were performed. The principal diagnosis was acute leukemia (63%). The 75% had haploidentical donors, and 50% used an antifungal in the month before transplantation. Voriconazole (69%) was the most frequently administered antifungal prophylaxis. The cumulative incidence of IFI was 5% (7 cases). Of the patients with IFIs, four began prophylaxis with voriconazole, one with caspofungin, and one with fluconazole. Additionally, six were possible cases, one was proven (Candida parapsilosis), and 1/7 died.

Conclusion

There were no differences in the incidence of IFI between patients who received prophylaxis with voriconazole and other antifungal agents.

Haploidentical transplantation is feasible and associated with reasonable outcomes despite major infective complications-A single center experience from India

Haploidentical stem cell transplantation (SCT) using post-transplantation cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis is a reasonable therapeutic option for patients who do not have a matched sibling donor. Between 2010 and June 2020, 257 patients underwent 269 Haploidentical transplantations, including 122 children. Indications included both malignant (56.8%) and non-malignant (43.2%) diseases. Conditioning regimens included both myeloablative (57.6%) and nonmyeloablative regimens (42.4%). Peripheral blood stem cells were the predominant graft source (96.2%). Based on the disease risk index, patients were classified into early-, intermediate-, and late-stage disease. Engraftment was seen in 205 patients (76.2%) whereas 39 (14.4%) died before engraftment and 23 (8.6%) had primary graft failure. The cumulative incidence of grade II-IV acute GVHD was 47.8% with a 23.9% incidence of grade III-IV acute GVHD. Chronic GVHD was seen in 41.9% with a 15.4% incidence of extensive chronic GVHD. More than 90% had at least 1 documented infection with a 44% incidence of bacterial, 71% viral, and 38% fungal infection. The 2-year overall survival is 40.5% ± 3.2% with a higher survival among children (48.2% ± 3.4%) compared to adults (34.2% ± 4.1%). Survival was poor with late-stage disease (23.6% ± 4.3%) compared to early- (62.5% ± 7.5%) and intermediate-stage (50.3% ± 4.3%). Factors adversely affecting survival included older age of patient (P = .007), late disease status (P = .000), nonmyeloablative conditioning regimen (P = .003), bone marrow as graft source (P = .006), presence of acute GVHD (P = .069), primary graft failure (P = .000), and presence of a documented bacterial (P = .000) and fungal infection (P = .000). On multivariate analysis, older age (P = .027), presence of acute GVHD (P = .033), documented bacterial infection (P = .000), documented fungal infection (P = .000) and primary graft failure (P = .012) continued to remain significant. Haploidentical SCT offers a reasonable chance of cure for patients with both malignant and nonmalignant hematological diseases. Strategies to reduce aGVHD and infection related mortality needs to be explored further. © 20XX American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Impact of mother donor, peripheral blood stem cells and measurable residual disease on outcomes after haploidentical hematopoietic cell transplantation with post-transplant cyclophosphamide in children with acute leukaemia

Haploidentical hematopoietic-cell transplantation using post-transplant cyclophosphamide(Haplo-PTCy) is a feasible procedure in children with haematologic malignancies. However, data of a large series of children with acute leukaemia(AL) in this setting is missing. We analysed 144 AL Haplo-PTCy paediatric recipients; median age was 10 years. Patients had acute lymphoblastic(ALL; n = 86) or myeloblastic leukaemia(AML; n = 58) and were transplanted in remission(CR1: n = 40; CR2: n = 57; CR3+: n = 27) or relapse (n = 20). Bone marrow was the graft source in 57%; donors were father (54%), mother (35%), or sibling (11%). Myeloablative conditioning was used in 87%. Median follow-up was 31 months. At day +100, cumulative incidence (CI) of neutrophil recovery and acute GVHD (II-IV) were 94% and 40%, respectively. At 2-years, CI of chronic GVHD and relapse, were 31%, 40%, and estimated 2-year overall survival (OS), leukaemia-free survival (LFS) and graft-versus-host-relapse-free survival (GRFS) were 52%, 44% and 34% respectively. For patients transplanted in remission, positive measurable residual disease (MRD) prior to transplant was associated with decreased LFS (p = 0.05) and GRFS (p = 0.003) and increased risk of relapse (p = 0.02). Mother donor was associated with increased risk of chronic GVHD (p = 0.001), decreased OS (p = 0.03) and GRFS (p = 0.004). Use of PBSC was associated with increased risk of chronic GVHD (p = 0.04). In conclusion, achieving MRD negativity pre-transplant, avoiding use of mother donors and PBSC as graft source may improve outcomes of Haplo-PTCy in children with AL.

Successful engraftment of haploidentical stem cell transplant with post-transplantation cyclophosphamide in a patient with adenosine deaminase deficiency

BACKGROUND

SCID are characterized by an imbalance in cellular and humoral immunity. Enzyme ADA deficiency represents from 10% to 15% of the SCID. This generates diminished maturation of the cell precursors. Treatments include enzyme replacement therapy, allogenic, or autologous HSCT with gene therapy, with HSCT being of choice when an identical HLA donor exists.

CASE REPORT

Male patient, without relevant family antecedents or consanguinity. The patient had multiple infections during the first months of life, evidencing low immunoglobulin levels, with absence of T and B lymphocytes, and natural killer cells. Severe combined immunodeficiencies are considered due to ADA deficiency; management was begun and is derived to our hospital. Admission at 8 months of life, with chronic malnutrition and psychomotor retardation. The HLA studies were conducted without finding an identical donor, taken to HSCT with haploidentical donor. Conditioning regimen with cyclophosphamide, fludarabine, melphalan, and thymoglobulin. This patient received prophylaxis for graft-versus-host disease with cyclophosphamide, cyclosporine, and methotrexate. A 22 months post-transplant, the patient was without immunosuppressants or immunoglobulin, without evidence of graft-versus-host disease or new infections.

CONCLUSIONS

The ADA deficiency is an infrequent pathology that can be potentially fatal if adequate treatment is not started. Haploidentical HSCT, using post-transplantation cyclophosphamide, emerges as a viable option with which good results can be achieved and improve the quality of life in patients with no other therapeutic alternatives.

Contemporary haploidentical stem cell transplant strategies in children with hematological malignancies

The barriers to HLA-mismatched or haploidentical hematopoietic stem cell transplantation (HSCT), namely GvHD and graft failure, have been overcome with novel transplant platforms. Post-transplant Cyclophosphamide (PTCy) is widely available, feasible and easy to implement. TCRαβ T and B cell depletion comes with consistent GvHD preventive benefits irrespective of age and indication. Naive T-cell depletion helps prevention of severe viral reactivations. The Beijing protocol shows promising outcomes in patients with poor remission status at the time of transplantation. For children, the toxicities and late outcomes related to these transplants are truly relevant as they suffer the most in the long run from transplant-related toxicities, especially chronic GvHD. While comparing the outcomes of different Haplo-HSCT approaches, one must understand the transplant immunobiology and factors affecting the transplant outcomes. Leukemia remission status at the time of conditioning is a consistent factor affecting the transplant outcomes using any of these platforms. Prospective comparison of these platforms lacks in a homogenous population; however, the evidence is growing, and this review highlights the areas of research gaps.

T-Cell-Replete Versus ex vivo T-Cell-Depleted Haploidentical Haematopoietic Stem Cell Transplantation in Children With Acute Lymphoblastic Leukaemia and Other Haematological Malignancies

Allogeneic haematopoietic stem cell transplantation (HSCT) represents a potentially curative option for children with high-risk or refractory/relapsed leukaemias. Traditional donor hierarchy favours a human leukocyte antigen (HLA)-matched sibling donor (MSD) over an HLA-matched unrelated donor (MUD), followed by alternative donors such as haploidentical donors or unrelated cord blood. However, haploidentical HSCT (hHSCT) may be entailed with significant advantages: besides a potentially increased graft-vs.-leukaemia effect, the immediate availability of a relative as well as the possibility of a second donation for additional cellular therapies may impact on outcome. The key question in hHSCT is how, and how deeply, to deplete donor T-cells. More T cells in the graft confer faster immune reconstitution with consecutively lower infection rates, however, greater numbers of T-cells might be associated with higher rates of graft-vs.-host disease (GvHD). Two different methods for reduction of alloreactivity have been established: in vivo T-cell suppression and ex vivo T-cell depletion (TCD). Ex vivo TCD of the graft uses either positive selection or negative depletion of graft cells before infusion. In contrast, T-cell-repleted grafts consisting of non-manipulated bone marrow or peripheral blood grafts require intense in vivo GvHD prophylaxis. There are two major T-cell replete protocols: one is based on post-transplantation cyclophosphamide (PTCy), while the other is based on anti-thymocyte globulin (ATG; Beijing protocol). Published data do not show an unequivocal benefit for one of these three platforms in terms of overall survival, non-relapse mortality or disease recurrence. In this review, we discuss the pros and cons of these three different approaches to hHSCT with an emphasis on the significance of the existing data for children with acute lymphoblastic leukaemia.

[Peripheral blood stem cell transplantation from HLA-mismatched unrelated donor or haploidentical donor for the treatment of X-linked agammaglobulinemia]

Allogeneic stem cell transplantation (allo-SCT) is currently the only curative option for patients with X-linked agammaglobulinemia (XLA). In this study, patient 1 aged 4 years who underwent allogeneic peripheral blood stem cell transplantation (allo-PBSCT) from HLA-mismatched unrelated donor; patient 2 aged 24 years (childhood onset) with primary cutaneous acral CD8⁺ T cell lymphoma who underwent allo-PBSCT from haploidentical relative donor. Both were treated by reduced toxicity myeloablative conditioning with post-transplantation cyclophosphamide (PTCy), anti-thymocyte globulin (ATG), methotrexate (MTX) and cyclosporine (CsA) for graft-versus-host-disease (GVHD) prophylaxis. In patient 1, neutrophil and platelet engraftment were observed on day 11 post-transplantation; the donor chimerism dropped on day 90 post-transplantation, and recovered on day 150 with donor lymphocyte infusion (DLI). In patient 2, neutrophil and platelet engraftment were observed on days 20 and 87 post-transplantation respectively, with complete donor chimerism on day 30 post-transplantation. The serum levels of IgG, IgM and IgA and the percentage of CD19⁺ B cells in peripheral blood of patients 1 and 2 returned to normal within 2 months and more than 1 year after transplantation respectively. There was no evidence of acute GVHD for the two patients. Patient 1 developed a limited type of skin chronic GVHD after DLI, which disappeared after anti-GVHD treatment. This is the first report of successful treatment for two XLA patients using PTCy with allo-PBSCT from HLA-mismatched unrelated donor or haploidentical donor, combining with improved conditioning, which expands the pool of eligible donors for patients with XLA.