Haploidentical Stem Cell Transplantation with Post-Transplant Cyclophosphamide for Primary Immune Deficiency Disorders in Children: Challenges and Outcome from a Tertiary Care Center in South India

[Setting up haploidentical hematopoietic cell transplantation in low- and middle-income countries: The Recommendations of the Francophone Society of Bone Marrow and Cellular Therapy (SFGM-TC)]

Nowadays, haploidentical hematopoietic cell transplantation (haplo-HCT) has been routinely used worldwide. However, this procedure is still rarely proposed in low- or middle-income countries. During the 13th annual harmonization workshops of the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC), a designated working group has proposed recommendations on how to set up such a transplantation in these countries. This was based on a review of the literature and expert-opinion as well as the previously published workshop on haplo-HCT of SFGM-TC (2016). Haploidentical donors appear to be a first alternative to HLA-matched siblings since the access to unrelated donor international registries are limited for several countries. While the procedure has the advantage of immediate access to several potential donors and of low cost, Haplo-HCT should be performed only in centers with a good experience of HLA-matched related transplantation (>10/year). In the absence of an HLA-matched related donor, haplo-HCT should be offered to all patients who are candidate for allo-HCT. Transplantation modalities should follow the conventional procedures with post-transplant cyclophosphamide as GVHD prophylaxis. Conditioning can be myeloablative or not according to each case. Our recommendations are intended to be general in scope and applicable to the majority of allo-HCT centers in these countries. An evaluation at regular basis is needed to assess the feasibility and to improve results.

Real-World Challenges of Haplo-Identical Hematopoietic Stem Cell Transplant in a Developing Country: A Single Center Experience

Hematopoietic stem cell transplant (HSCT) is potentially, the sole curative option for many malignant and non-malignant hematological disorders. Finding a human leukocyte antigen (HLA) compatible donor remains one of the limiting factors, hampering the utilization of HSCT. However, the introduction of post-transplant cyclophosphamide (PTCy) has improved the outcomes of haploidentical transplants making it a suitable option for patients lacking HLA-compatible donors. We collected data from 44 patients who underwent haplo-identical allogeneic stem cell transplants at the Armed Forces Bone Marrow Transplant Center/National Institute of Blood and Marrow Transplant (AFBMTC/NIBMT) from the year 2015 to 2022. The diseases were divided into three categories, i.e., bone marrow failure (BMF) syndromes, hematological malignancies (HM) and miscellaneous (Misc) groups. Median age at transplant was 18 (01-39) years. Transplant indications included aplastic anemia (AA) in 21 (47.7%) cases, 15 (34.1%) HM, and eight (18.2%) cases falling in the Misc groups. A maximum number of graft failures occurred in the BMF group; primary graft failure in 07 (33.3%) cases and secondary graft failure in four (19%) cases, (p-value < 0.05). Acute graft versus host disease (aGVHD) grade II-IV occurred in nine (20.5%) cases while chronic graft versus host disease (cGVHD) occurred in 10 (22.7%) cases. Cytomegalovirus (CMV) reactivation was seen in 31 (70.5%) cases. Maximum CMV reactivation was seen in HM group 13 (86.6%) cases, (p-value < 0.05) as compared to BMF (71.4%) and Misc groups (37.5%). Post-transplant cyclophosphamide (PTCy) based regimens, early neutrophil engraftment, and patients with GVHD had better survival outcomes (p-value < 0.05) overall survival (OS), and relapse-free survival (RFS). and GVHD-free relapse-free survival (GFRS) were significantly better in cases with early neutrophil engraftment. OS of the study cohort was 50% while disease-free survival (DFS) and GFRS were 45.5% and 36.4%, respectively.

Survival After Hematopoietic Stem Cell Transplantation in Severe Combined Immunodeficiency (SCID): A Worldwide Review of the Prognostic Variables

This study aims to perform an extensive review of the literature that evaluates various factors that affect the survival rates of patients with severe combined immunodeficiency (SCID) after hematopoietic stem cell transplantation (HSCT) in developed and developing countries. An extensive search of the literature was made in four different databases (PubMed, Embase, Scopus, and Web of Science). The search was carried out in December 2022 and updated in July 2023, and the terms such as "hematopoietic stem cell transplantation," "bone marrow transplant," "mortality," "opportunistic infections," and "survival" associated with "severe combined immunodeficiency" were sought based on the MeSH terms. The language of the articles was "English," and only articles published from 2000 onwards were selected. Twenty-three articles fulfilled the inclusion criteria for review and data extraction. The data collected corroborates that early HSCT, but above all, HSCT in patients without active infections, is related to better overall survival. The universal implementation of newborn screening for SCID will be a fundamental pillar for enabling most transplants to be carried out in this "ideal scenario" at an early age and free from infection. HSCT with an HLA-identical sibling donor is also associated with better survival rates, but this is the least common scenario. For this reason, transplantation with matched unrelated donors (MUD) and mismatched related donors (mMRD/Haploidentical) appear as alternatives. The results obtained with MUD are improving and show survival rates similar to those of MSD, as well as they do not require manipulation of the graft with expensive technologies. However, they still have high rates of complications after HSCT. Transplants with mMRD/Haplo are performed just in a few large centers because of the high costs of the technology to perform CD3/CD19 depletion and TCRαβ/CD19 depletion or CD34 + selection techniques in vitro. The new possibility of in vivo T cell depletion using post-transplant cyclophosphamide could also be a viable alternative for performing mMRD transplants in centers that do not have this technology, especially in developing countries.

Changing outcomes of stem cell transplantation in primary immunodeficiencies: Results from a tertiary-care charitable trust hospital in Mumbai

Background

Hematopoietic stem cell transplantation in primary immunodeficiency disorders has come a long way since the first transplant in 1968. In India, pediatric stem cell transplantation long-term survival outcomes range from 62.5% to 75%, compared to 90% in high-income countries.

Objective

We present single-center data of primary immunodeficiency transplants with immune-reconstitution evaluation after transplantation from a charitable trust hospital.

Methods

Retrospective data of children transplanted for primary immunodeficiency disorders from March 2019 to March 2022 in a newly established transplant unit were collected. Data of pretransplant infections and comorbidities, surveillance for carbapenem-resistant Enterobacteriaceae, transplant characteristics, donor source, graft-versus-host disease, posttransplant infections, immune reconstitution, overall survival at 1 year, and immunodeficiency-free survival were collated.

Results

Twenty-one patients underwent transplantation for primary immunodeficiency disorders. The median age at transplantation was 3 years and 5 months (range, 7 months to 17 years). Seventy-five percent of the cohort had organ involvement, with lung being the most common organ involved, followed by central nervous system. Fifty-two percent of children had peritransplant infections, with most of them recognized at the pretransplant assessment. Among 20 of 21 children with engraftment, 94% had complete chimerism initially, with 33% developing mixed chimerism over time. The median duration of immunosuppression was 3 months after transplantation, and only 1 child required systemic graft-versus-host disease treatment for more than a year. Immune-reconstitution showed good T-cell recovery at 3 months and naive T-cell production at 6 months. There was no regimen-related or sepsis-related mortality. Overall survival of the cohort was 95% at 1-year follow-up. Immunodeficiency-free survival was 86% after a median follow-up of 20 months.

Conclusions

Immunodeficiency-free and graft-versus-host disease-free survival can be achieved in the majority of children with primary immunodeficiencies using enhanced supportive care and the latest transplantation algorithms.

Fatal Severe Cytokine Release Syndrome Post-haploidentical Stem Cell Transplant With Post-transplant Cyclophosphamide in an Infant With Severe Combined Immunodeficiency and Disseminated Bacille Calmette-Guérin Infection

INTRODUCTION

Severe Combined Immunodeficiency (SCID) is a primary immunodeficiency disorder characterized by absent or dysfunctional T lymphocytes, leading to defective cellular and humoral immunity requiring urgent hematopoietic stem cell transplantation (HSCT). We report a case of SCID with disseminated Bacille Calmette-Guérin (BCG) infection who developed cytokine release syndrome (CRS) and possible Immune reconstitution inflammatory syndrome (IRIS) after Haploidentical HSCT with post-transplant cyclophosphamide.

METHODS

Data were retrospectively retrieved from electronic medical records.

RESULT

A 5-month-old male infant was referred with fever, cough, and generalized maculopapular rash for 15 days, and had pallor without hepatosplenomegaly or lymphadenopathy. He had a history of previous male sibling death at 6 months of age due to pneumonia. Investigations: hemoglobin: 4.7 g/dL, TLC-6.37×103/uL, absolute lymphocytes: 0.98×103/uL, platelets: 319×103/uL, bilateral patchy opacities in both lung fields, and low immunoglobulin levels. Lymphocyte subset analysis revealed T-, B+, NK- SCID. Genetic analysis showed a hemizygous mutation in IL2RG (c.314A>G). The child received intravenous (IV) antibiotics, antifungal, antitubercular drugs, irradiated blood products, and IV immunoglobulins. Urgent haploidentical HSCT from the mother was planned. Conditioning was Fludarabine-40 mg/m2/d for 4 days, cyclophosphamide: 14.5 mg/kg/d for 2 days. He received peripheral blood hematopoietic stem cells with CD34- 15×106 cells/kg and CD3- 805×106 cells/kg. Within 2 hours of stem cell infusion, he developed respiratory distress, fever, shock, and flaring of rash. Methylprednisolone was started in view of CRS. On day+2, he had sudden desaturation and bradycardia needing mechanical ventilation and inotropes. His inflammatory markers were elevated (Ferritin: 3640 ng/mL, IL-6:5000 pg/mL, CRP:255 mg/L). In view of high-grade CRS, he received an injection of tocilizumab 8 mg/kg on day +2 and day +4. He received post-transplant cyclophosphamide 5 mg/kg on day +3. The endotracheal secretion GeneXpert was positive for Mycobacterium supporting the diagnosis of disseminated tuberculosis. Our patient had disseminated BCG infection which could also be contributory in the initiation of IRIS as the mother was immunized with the BCG vaccine in childhood so she must be having cytotoxic T cells specific for BCG, which were transferred to the infant with peripheral blood stem cell product. He succumbed to severe acute respiratory distress syndrome and multiorgan dysfunction on day +5 post-transplant.

CONCLUSIONS

In haploidentical HSCT of SCID, post-transplant course can be complicated by CRS and IRIS as these patients are inefficient in mounting any response to infused donor lymphocytes resulting in their unregulated growth.

T-lymphocyte depleted transplants for inborn errors of immunity

INTRODUCTION

Hematopoietic stem cell transplantation is a curative treatment for many inborn errors of immunity (IEI). Incremental improvements and advances in care have led to high rates of >85% survival and cure in many of these diseases. Improvements in HLA-classification and matching have led to increased survival using HLA-matched donors, but survival using T-lymphocyte-depleted mismatched grafts remained significantly worse until fairly recently. Advances in T-lymphocyte depletion methods and graft engineering, although not specific to IEI, have been widely adopted and instrumental in changing the landscape of donor selection, such that a donor should now be possible for every patient.

AREAS COVERED

A literature review focusing on T-lymphocyte depletion methodologies and treatment results was performed. The importance of early T-lymphocyte immunoreconstitution to protect against viral infection is reviewed. Two main platforms now dominate the field - immune-magnetic selection of specific cell types and post-transplant chemotherapeutic targeting of rapidly proliferating allo-reactive T-lymphocytes - the emerging literature on these reports, focusing on IEI, is explored, as well as the impact of serotherapy on early immunoreconstitution.

EXPERT OPINION

Pharmacokinetic monitoring of serotherapy agents, and use of co-stimulatory molecule blockade are likely to become more widespread. Post-transplant cyclophosphamide or TCR depletion strategies are likely to become the dominant methods of transplantation for nonmalignant diseases.

CD3+TCRαβ/CD19+ depleted mismatched family or unrelated donor salvage stem cell transplantation for graft dysfunction in inborn errors of immunity

BACKGROUND

A minority of children experience significant graft dysfunction after an allogeneic hematopoietic stem cell transplant (HSCT) for inborn errors of immunity (IEI). The optimal approach to salvage HSCT is unclear with respect to conditioning regimen and stem cell source. This single-centre retrospective case series reports the outcomes of salvage CD3+TCRαβ/CD19 depleted mismatched family or unrelated donor stem cell transplantation (TCRαβ-SCT) between 2013 - 2022 for graft dysfunction in 12 children with IEI.

OBJECTIVES

Outcomes of interest were overall survival (OS), event free survival (EFS), graft-versus-host disease (GvHD)-free and event-free survival (GEFS), toxicities, GvHD, viremia and long-term graft function.

STUDY DESIGN

A retrospective audit of patients who underwent second CD3+TCRαβ/CD19 depleted mismatched donor graft using Treosulfan-based reduced toxicity myeloablative conditioning.

RESULTS

Median age at first HSCT was 8.76 months (range, 2.5 months - 6 years) and at second TCRαβ-SCT was 3.6 years (1.2 - 11 years). Median interval between first and second HSCT was 1.7 years (3 months - 9 years). The primary diagnoses were: severe combined immunodeficiency (SCID) (n=5) and non-SCID IEI (n=7). The indications for second HSCT were: primary aplasia (n=1), secondary autologous reconstitution (n=6), refractory aGVHD (n=3) and secondary leukemia (n=1). Donors were either haploidentical parental donors (n=10) or mismatched unrelated donors (n=2). All received TCRαβ/CD19-depleted-PBSC with a median CD34+ cell dose of 9.3 × 10⁶/kg (2.8-32.3 × 10⁶/kg) and a median TCRαβ+ cell dose of 4 × 10⁴/kg (1.3-19.2 × 10⁴/kg). All engrafted with median days to neutrophil and platelet recovery of 15 (12-24) and 12 (9-19). One developed secondary aplasia and one had secondary autologous reconstitution, but both underwent a successful third HSCT. Four (33%) had grade II aGvHD and none had grade III-IV aGvHD. None had cGvHD but one developed extensive cutaneous cGVHD after third HSCT using PBSC and ATG. Nine (75%) were noted to have at least one episode of blood viremia with HHV6 (n=6, 50%), adenovirus (n=6, 50%), EBV (n=3, 25%) or CMV (n=3; 25%). Median duration of follow-up was 2.3 years (range: 0.5 - 10 years) and the 2-year OS, EFS and GEFS were 100% (95% confidence interval, 0-100%), 73% (37-90%) and 73% (37%-90%) respectively.

CONCLUSIONS

TCRαβ-SCT from mismatched family or unrelated donors, using a chemotherapy only regimen, is a safe alternative donor salvage transplant strategy for second HSCT in patients without a suitably matched donor.

Personalized hematopoietic stem cell transplantation for inborn errors of immunity

Patients with inborn errors of immunity (IEI) have been transplanted for more than 50 years. Many long-term survivors have ongoing medical issues showing the need for further improvements in how hematopoietic stem cell transplantation (HSCT) is performed if patients in the future are to have a normal quality of life. Precise genetic diagnosis enables early treatment before recurrent infection, autoimmunity and organ impairment occur. Newborn screening for severe combined immunodeficiency (SCID) is established in many countries. For newly described disorders the decision to transplant is not straight-forward. Specific biologic therapies are effective for some diseases and can be used as a bridge to HSCT to improve outcome. Developments in reduced toxicity conditioning and methods of T-cell depletion for mismatched donors have made transplant an option for all eligible patients. Further refinements in conditioning plus precise graft composition and additional cellular therapy are emerging as techniques to personalize the approach to HSCT for each patient.

KIR in Allogeneic Hematopoietic Stem Cell Transplantation: Need for a Unified Paradigm for Donor Selection

Allogeneic hematopoietic stem cell transplantation (aHSCT) is a lifesaving therapy for hematological malignancies. For years, a fully matched HLA donor was a requisite for the procedure. However, new immunosuppressive strategies have enabled the recruitment of viable alternative donors, particularly haploidentical donors. Over 95% of patients have at least two potential haploidentical donors available to them. To identify the best haploidentical donor, the assessment of new immunogenetic criteria could help. To this end, the clinical benefit of KIR genotyping in aHSCT has been widely studied but remains contentious. This review aims to evaluate the importance of KIR-driven NK cell alloreactivity in the context of aHSCT and explain potential reasons for the discrepancies in the literature. Here, through a non-systematic review, we highlight how the studies in this field and their respective predictive models or scoring strategies could be conceptually opposed, explaining why the role of NK cells remains unclear in aHCST outcomes. We evaluate the limitations of each published prediction model and describe how every scoring strategy to date only partly delivers the requirements for optimally effective NK cells in aHSCT. Finally, we propose approaches toward finding the optimal use of KIR genotyping in aHSCT for a unified criterion for donor selection.

Pediatric immune deficiencies: current treatment approaches

PURPOSE OF REVIEW

To summarize the currently available definitive therapies for patients with inborn errors of immunity (IEIs) with a strong focus on recent advances in allogeneic hematopoietic cell transplantation (HCT) and gene therapy, including the use of alternative donors, graft manipulation techniques, less toxic approaches for pretransplant conditioning and gene transfer using autologous hematopoietic stem cells.

RECENT FINDINGS

In the absence of a matched sibling or a matched related donor, therapeutic alternatives for patients with IEIs include alternative donor transplantation or autologous gene therapy, which is only available for selected IEIs. In recent years, several groups have published their experience with haploidentical hematopoietic cell transplantation (HHCT) using different T-cell depletion strategies. Overall survival and event free survival results, although variable among centers, are encouraging. Preliminary results from autologous gene therapy trials with safer vectors and low-dose busulfan conditioning have shown reproducible and successful results. Both strategies have become valid therapeutic options for patients with IEIs. A new promising and less toxic conditioning regimen strategy is also discussed.

SUMMARY

Definitive therapies for IEIs with HCT and gene therapy are in stage of evolution, not only to refine their efficacy and safety but also their reach to a larger number of patients.

Stem-cell transplantation for children with primary immune deficiencies: A retrospective study of 19 patients from one center in Mexico

INTRODUCTION

For many patients with Primary immune deficiency (PID), stem-cell transplantation (SCT) may be lifesaving.

OBJECTIVE

To review our experience of 11 years transplanting children with PID in Mexico.

METHODS

Chart review of patients who underwent SCT from 2008 to 2018, to describe their diagnoses, time to transplant, conditioning regime, survival rate and outcomes. All patients received post-transplant cyclophosphamide as graft-versus-host-disease (GVHD) prophylaxis.

RESULTS

19 patients with combined, phagocytic or syndromic PID from 5 states. Twelve of them were male (58%) and 14 survive (79%). Mean age at HSCT was 41.9 months; mean time from diagnosis, 31.2 months. Seven grafts were umbilical cord and 12 haploidentical. The conditioning regime was myeloablative, with seven primary graft failures. Two patients had partial and 10 full chimerism. Five patients died within 2 months after transplant. Immune reconstitution was complete in 11 of 19 patients. We found a prevalence of 21% GVHD.

DISCUSSION

We describe 19 patients from Mexico with 8 PID diagnoses who underwent allogenic HSCT over a period of 11 years. Survival rate and other outcomes compare well with industrialized countries. We recommend the use of post-transplant cyclophosphamide to prevent GVHD in scenarios of resource scarcity and a lack of HLA-identical donors.

Hematopoietic Cell Transplantation for Inborn Errors of Immunity Other than Severe Combined Immunodeficiency in Japan: Retrospective Analysis for 1985-2016

PURPOSE

Hematopoietic cell transplantation (HCT) is a curative therapy for most patients with inborn errors of immunity (IEI). We conducted a nationwide study on HCT for patients with IEI other than severe combined immunodeficiency (non-SCID) in Japan.

METHODS

Data from the Japanese national database (Transplant Registry Unified Management Program, TRUMP) for 566 patients with non-SCID IEI, who underwent their first HCT between 1985 and 2016, were retrospectively analyzed.

RESULTS

The 10-year overall survival (OS) and event-free survival (EFS) were 74% and 64%, respectively. The 10-year OS for HCT from unrelated bone marrow (URBM), accounting for 39% of HCTs, was comparable to that for HCT from matched sibling donor (MSD), 79% and 81%, respectively. HCT from unrelated cord blood (URCB), accounting for 28% of HCTs, was also common, with a 10-year OS of 69% but less robust engraftment. The intensity of conditioning was not associated with OS or neutrophil recovery; however, myeloablative conditioning was more frequently associated with infection-related death. Patients who received myeloablative irradiation showed poor OS. Multivariate analyses revealed that HCT in 1985-1995 (hazard ratio [HR], 2.0; P = 0.03), URCB (HR, 2.0; P = 0.01), and related donor other than MSD (ORD) (HR, 2.9; P < 0.001) were associated with poor OS, and URCB (HR, 3.6; P < 0.001) and ORD (HR, 2.7; P = 0.02) showed a higher incidence of retransplantation.

CONCLUSIONS

We present the 1985-2016 status of HCT for non-SCID IEI in Japan with sufficient statistical power, highlighting the potential of URBM as an alternative donor and the feasibility of reduced intensity conditioning.

CMV Infection and CMV-Specific Immune Reconstitution Following Haploidentical Stem Cell Transplantation: An Update

Haploidentical stem cell transplantation (haploSCT) has advanced to a common procedure for treating patients with hematological malignancies and immunodeficiency diseases. However, cure is seriously hampered by cytomegalovirus (CMV) infections and delayed immune reconstitution for the majority of haploidentical transplant recipients compared to HLA-matched stem cell transplantation. Three major approaches, including in vivo T-cell depletion (TCD) using antithymocyte globulin for haploSCT (in vivo TCD-haploSCT), ex vivo TCD using CD34 + positive selection for haploSCT (ex vivo TCD-haploSCT), and T-cell replete haploSCT using posttransplant cyclophosphamide (PTCy-haploSCT), are currently used worldwide. We provide an update on CMV infection and CMV-specific immune recovery in this fast-evolving field. The progress made in cellular immunotherapy of CMV infection after haploSCT is also addressed. Groundwork has been prepared for the creation of personalized avenues to enhance immune reconstitution and decrease the incidence of CMV infection after haploSCT.

Case Report: Haploidentical Bone Marrow Transplantation in Two Brothers With Wiskott-Aldrich Syndrome Using Their Father as the Donor

Wiskott-Aldrich syndrome (WAS) is an X-linked genetic disorder with a variable phenotypic expression that includes thrombocytopenia, eczema, and immunodeficiency. Some patients may also exhibit autoimmune manifestations. Patients with WAS are at increased risk of developing malignancies such as lymphoma. Allogeneic hematopoietic cell transplantation remains the only curative treatment. Haploidentical bone marrow transplantation (haplo-BMT) with post-transplant cyclophosphamide (PT-CY) has more recently been applied in WAS. Here, we report two brothers who underwent successful T-cell replete haplo-BMT with PT-CY at ages 9 months and 4 years using their father as the donor. Our myeloablative regimen was well-tolerated with minimal organ toxicity and no acute or chronic graft vs. host disease (GvHD). Haplo-BMT may be considered as a safe and effective option for patients with WAS who do not have available human leukocyte antigen (HLA) matched donors.

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.

Haploidentical Hematopoietic Cell Transplantation Using Post-transplant Cyclophosphamide for Children with Non-malignant Diseases

Haploidentical hematopoietic cell transplantation (HCT) is a valuable curative option for children with non-malignant diseases. Haploidentical HCT using post-transplant cyclophosphamide (PTCy) is a readily available option in the absence of an HLA-matched donor. We conducted a retrospective single-center study on the outcome of haploidentical HCT in children with non-malignant diseases. We gathered data from 44 patients underwent HCT in the period 2015 to 2020. The indications for HCT were bone marrow failure, primary immunodeficiency, metabolic disorders, and hemoglobinopathy. Median age at HCT was 4 years (range 0.7-20). The conditioning regimens were myeloablative (n = 17) or reduced intensity (n = 27). After a median follow-up of 20 months (range 4-71), 2-year overall survival was 89% and 2-year GvHD-free relapse-free survival (GRFS) was 66%. Incidence of primary graft failure was 13.6%. Cumulative incidence of grade II-IV acute and moderate/severe chronic GvHD were 20% and 6.4%, respectively. Younger age at HCT (< 4 years) and primary immunodeficiency were significantly associated with better GRFS (p < 0.05). In conclusion, haploidentical HCT using PTCy is feasible and curative in children with non-malignant diseases lacking an HLA-matched donor. Early diagnosis and referral in addition to timely treatment can further improve outcomes.

Wiskott Aldrich Syndrome: A Multi-Institutional Experience From India

Background

Wiskott Aldrich syndrome (WAS) is characterized by bleeding manifestations, recurrent infections, eczema, autoimmunity, and malignancy. Over the last decade, improved awareness and better in-house diagnostic facilities at several centers in India has resulted in increased recognition of WAS. This study reports collated data across major primary immunodeficiency diseases (PID) centers in India that are involved in care of children with WAS and highlights the varied clinical presentations, genetic profile, and outcomes of patients in India.

Methods

Request to share data was sent to multiple centers in India that are involved in care and management of patients with PID. Six centers provided requisite data that were compiled and analyzed.

Results

In this multi-institutional cohort, clinical details of 108 patients who had a provisional diagnosis of WAS were received. Of these, 95 patients with 'definite WAS' were included Fourteen patients were classified as XLT and 81 patients as WAS. Median age at onset of symptoms of patients was 3 months (IQR 1.6, 6.0 months) and median age at diagnosis was 12 months (IQR 6,48 months). Clinical profile included bleeding episodes (92.6%), infections (84.2%), eczema (78.9%), various autoimmune manifestations (40%), and malignancy (2.1%). DNA analysis revealed 47 variants in 67 cases. Nonsense and missense variants were the most common (28.4% each), followed by small deletions (19.4%), and splice site defects (16.4%). We also report 24 novel variants, most of these being frameshift and nonsense mutations resulting in premature termination of protein synthesis. Prophylactic intravenous immunoglobulin (IVIg) was initiated in 52 patients (54.7%). Hematopoietic stem cell transplantation (HSCT) was carried out in 25 patients (26.3%). Of those transplanted, disease-free survival was seen in 15 patients (60%). Transplant related mortality was 36%. Outcome details were available for 89 patients. Of these, 37% had died till the time of this analysis. Median duration of follow-up was 36 months (range 2 weeks- 12 years; IQR 16.2 months- 70 months).

Conclusions

We report the first nationwide cohort of patients with WAS from India. Bleeding episodes and infections are common manifestations. Mortality continues to be high as curative therapy is not accessible to most of our patients.

Primary immunodeficiency-related genes in neonatal intensive care unit patients with various genetic immune abnormalities: a multicentre study in China

Objectives

The present phenotype-based disease classification causes ambiguity in diagnosing and determining timely, effective treatment options for primary immunodeficiency (PID). In this study, we aimed to examine the characteristics of early-onset PID and proposed a JAK-STATopathy subgroup based on their molecular defects.

Methods

We reviewed 72 patients (< 100 days) retrospectively. These patients exhibited various immune-related phenotypes and received a definitive molecular diagnosis by next-generation sequencing (NGS)-based tests. We evaluated the PID-causing genes and clinical parameters. We assessed the genes that shared the JAK-STAT signalling pathway. We also examined the potential high risks related to the 180-day death rate.

Results

We identified PID disorders in 25 patients (34.72%, 25/72). The 180-day mortality was 26.39% (19/72). Early onset of disease (cut-off value of 3.5 days of age) was associated with a high 180-day death rate (P = 0.009). Combined immunodeficiency with associated or syndromic features comprised the most common PID class (60.00%, 15/25). Patients who presented life-threatening infections were most likely to exhibit PID (odds ratio [OR] = 2.864; 95% confidence interval [CI]: 1.047-7.836). Twelve out of 72 patients shared JAK-STAT pathway defects. Seven JAK-STATopathy patients were categorised as PID. They were admitted to NICUs as immunological emergencies. Most of them experienced severe infections and thrombocytopenia, with 4 succumbing to an early death.

Conclusions

This study confirmed that NGS can be utilised as an aetiological diagnostic method of complex immune-related conditions in early life. Through the classification of PID as pathway-based subtypes, we see an opportunity to dissect the heterogeneity and to direct targeted therapies.

Haploidentical Stem Cell Transplant with Post-Transplant Cyclophosphamide in Pediatric Hemophagocytic Lymphohistiocytosis

PURPOSE

Primary hemophagocytic lymphohistiocytosis is a severe and uncommon disease affecting pediatric patients. Genetic abnormalities have been related to altered apoptosis and exaggerated inflammatory reactions. Chemoimmunotherapy and stem cell transplantation are treatment options, but transplant is the only curative treatment. Here we aim to describe the treatment with hematopoietic stem cell transplantation with a novel strategy and the outcomes.

METHODS

An observational, descriptive, case series study was performed in pediatric patients of two high complexity medical centers in Colombia. Data was collected retrospectively between 2015 and 2020.

RESULTS

We describe five pediatric cases with a diagnosis of primary hemophagocytic lymphohistiocytosis. All were treated with replete-cell haploidentical hematopoietic stem transplantation, reduced-intensity conditioning, and post-transplant cyclophosphamide, in two high-complexity centers in Colombia. All patients are alive, and one is receiving management for chronic graft-versus-host disease.

CONCLUSION

To the best of our knowledge, there are few reports in the literature with this strategy, promising a possible alternative when there are no other donor options.

Successful Haploidentical Stem Cell Transplant With Posttransplant Cyclophosphamide in Wiskott-Aldrich Syndrome With Myeloablative Conditioning

Hematopoietic stem cell transplant (HSCT) is the only curative treatment modality for Wiskott-Aldrich syndrome. Haploidentical HSCT with posttransplant cyclophosphamide (PTCy) is an upcoming option in children with nonmalignant conditions. However, only few cases have been reported for Wiskott-Aldrich syndrome HSCT with PTCy approach. Here we report a 4-year-old boy, treated successfully by haploidentical HSCT with myeloablative conditioning (busulfan, fludarabine, and thiotepa) and PTCy. Posttransplant chimerism was fully donor. Of 13 cases (current case and other 12 published cases) 10 are alive and disease free after haploidentical HSCT with PTCy. Haploidentical HSCT with PTCy using myeloablative conditioning is feasible and safe.

Multicenter Outcome of Hematopoietic Stem Cell Transplantation for Primary Immune Deficiency Disorders in India

Background

Hematopoietic stem cell transplantation (HSCT) is the curative option for many primary immune deficiency disorders (PID). In the last 5 years, increased awareness, availability of diagnostics based on flow cytometry, genetic testing, improved supportive care, use of reduced toxicity conditioning, and success of haploidentical donor HSCT have improved access to HSCT for children with PID in India. We present results on children with PID who underwent HSCT across India and the factors that influenced outcome.

Patients and Methods

We collected retrospective data on the outcome of HSCT for PID from seven centers. We analyzed the impact of the type of PID, conditioning regimen, time period of HSCT- before or after January 2016, graft versus host disease prophylaxis, cause of mortality and overall survival.

Results

A total of 228 children underwent HSCT for PID at a median age of 12 months (range, 1 to 220 months) with a median follow up of 14.4 months. Infants accounted for 51.3% of the cohort and the male female ratio was 3:1. SCID (25%) and HLH (25%) were the more frequent diagnoses. Matched family donor was available in 36.4% and 44.3% children had a haploidentical HSCT. Reduced and myeloablative conditioning regimens were used with 64% children receiving a treosulfan based conditioning regimen. Peripheral blood stem cells were the predominant graft source at 69.3%. The survival in infants (60.2%) was inferior to children aged over 1 year (75.7% p value = 0.01). Children with Wiskott Aldrich syndrome (74.3%) and chronic granulomatous disease (82.6%) had the best outcomes. The survival was superior in children receiving HSCT from a matched sibling (78%) versus an alternate donor HSCT (61% p value = 0.04). In the cohort transplanted after January 2016 survival improved from 26.8% to 77.5% (p value = 0.00). Infection remains the main cause of mortality at in over 50% children. The 5-year overall survival rate was 68%.

Conclusion

Survival of children with PID undergoing HSCT in India has improved dramatically in last 5 years. Alternate donor HSCT is now feasible and has made a therapeutic option accessible to all children with PID.

Prenatal Diagnosis for Primary Immunodeficiency Disorders-An Overview of the Indian Scenario

Prenatal Diagnosis (PND) forms an important part of primary preventive management for families having a child affected with primary immunodeficiency. Although individually sparse, collectively this group of genetic disorders represents a significant burden of disease. This paper discusses the prenatal services available for affected families at various centers across the country and the challenges and ethical considerations associated with genetic counseling. Mutation detection in the index case and analysis of chorionic villous sampling or amniocentesis remain the preferred procedures for PND and phenotypic analysis of cordocentesis sample is reserved for families with well-characterized index case seeking PND in the latter part of the second trimester of pregnancy. A total of 112 families were provided PND services in the last decade and the presence of an affected fetus was confirmed in 32 families. Post-test genetic counseling enabled the affected families to make an informed decision about the current pregnancy.

Gene therapy for primary immunodeficiencies: up-to-date

INTRODUCTION

Primary immunodeficiencies (PIDs) are monogenic disorders of the immune system associated with increased susceptibility to life-threatening infection. Curative treatment has been limited to hematopoietic stem cell transplant (HSCT), however toxic immunosuppression, graft failure, and graft versus host disease greatly reduce overall survival rates. Gene therapy is a targeted curative therapy that reduces these risks by utilizing autologous hematopoietic stem cells. The treatment has found significant success and is anticipated to become the standard of care in a number of PIDs.

AREAS COVERED

This review is a summary of the developments in gene therapy, gene editing, and current gene therapy approaches in specific PIDs.

EXPERT OPINION

The field of gene therapy has rapidly developed over the last three decades, with the first licensed pharmaceutical gene therapy product now available. After initial clinical trials discovered serious adverse events in the form of insertional oncogenesis, significant improvements in vector design have made the treatment a viable curative therapy. Cryopreservation has expanded the scope of gene therapy by increasing accessibility of the product to wider geographic locations. Targeted gene editing using engineered nucleases, while still in early stages of development, will further add to the repertoire of potential treatments available for PIDs.

Hematopoietic Stem Cell Transplantation in Children with Inborn Errors of Immunity: a Multi-center Experience in Colombia

PURPOSE

To characterize the pediatric population with inborn errors of immunity (IEI) that was treated with hematopoietic stem cell transplantation (HSCT) in three reference centers in Colombia. What have been the characteristics and outcomes of hematopoietic stem cell transplantation in pediatric patients with inborn errors of immunity in three reference care centers in Colombia between 2007 and 2018?

METHODS

We conducted an observational, retrospective cohort study in children with a diagnosis of IEI who underwent HSCT between 2007 and 2018.

RESULTS

Forty-seven patients were identified, and 5 were re-transplanted. Sixty-eight percent were male. The median age at diagnosis was 0.6 years, and for HSCT was 1.4 years. The most common diseases were chronic granulomatous disease (38%) followed by severe combined immune deficiencies (19%) and hemophagocytic lymphohistiocytosis (15%). Cord blood donors were the most used source of HSCT (44%). T cell-replete grafts from haploidentical donors using post-transplantation cyclophosphamide represent 37% of the cohort. All patients received conditioning, 62% with a non-myeloablative regimen. Calcineurin inhibitors were the main graft-versus-host disease prophylaxis (63.8%). Acute graft-versus-host disease developed in 35% of the total patients. The most frequent post-transplant infections were viral and fungal infections. The 1-year overall survival rates for the patients who received HSCT from identical, haploidentical, and cord sources were 80%, 72%, and 63%, respectively. The 5-year overall survival was 63%.

CONCLUSIONS

HSCT is a curative treatment option for some IEI and can be performed with any donor type. Early and timely treatment in referral centers can improve survival.

Haploidentical stem cell transplantation with post-transplant cyclophosphamide for osteopetrosis and other nonmalignant diseases

Allogeneic hematopoietic stem cell transplantation (HSCT) is curative for a variety of nonmalignant disorders including osteopetrosis, bone marrow failures, and immune deficiencies. Haploidentical HSCT is a readily available option in the absence of a matched donor, but engraftment failure and other post-transplant complications are a concern. Post-transplant cyclophosphamide (PT-Cy) regimens are gaining popularity and recent reports show promising results. We report our experience with nine pediatric patients with nonmalignant diseases who were transplanted from a haploidentical donor with PT-Cy. From 2015 to 2019, nine children with nonmalignant diseases underwent haploidentical HSCT with PT-Cy, two as a second transplant and seven as primary grafts after upfront serotherapy and busulfan-based myeloablative conditioning. Patient’s diseases included osteopetrosis (n = 5), congenital amegakaryocytic thrombocytopenia (n = 2), hemophagocytic lymphohistiocytosis (n = 1), and Wiskott Aldrich syndrome (n = 1). Two patients failed to engraft following upfront PT-Cy transplants, one was salvaged with a second PT-Cy transplant, and the other with a CD34+ selected graft. None of the patients suffered from graft-versus-host disease. Three patients died from early posttransplant infectious complications and six patients are alive and well. In conclusion, haploidentical HSCT with PT-Cy is a feasible option for pediatric patients with nonmalignant diseases lacking a matched donor.

A comparison of post-transplantation cyclophosphamide versus antithymocyte-globulin in patients with hematological malignancies undergoing HLA-matched unrelated donor transplantation

Post-transplantation cyclophosphamide (PTCy) and antithymocyte-globulin (ATG) are the most commonly used regimens for prophylaxis of graft-versus-host disease (GVHD). We compared these 2 regimens in human leukocyte antigen (HLA)-matched unrelated donor hematopoietic stem cell transplantation (HSCT) patients with hematological malignancies. We retrospectively analyzed consecutive adult patients with hematological malignancies who underwent HLA-matched unrelated donor-HSCT at Chungnam National University Hospital (Daejeon, South Korea) between January 2013 and January 2019. Patients who received a second transplantation or who had refractory disease were excluded. We included 34 patients (12 and 22 in the PTCy and ATG groups respectively). All graft sources were peripheral blood stem cells. The estimated 20-month overall survival rates were 75.0% for PTCy and 81.6% for ATG patients (P = .792), and the 20-month relapse rates were 41.7% and 34.3% (P = .491), respectively. The cumulative incidences of grade 2 to 4 acute GVHD were 16.7% and 30.6% (P = .551), respectively; the estimated 20-month limited and extensive chronic GVHD rates were 59.1% and 78.8% (P = .718), respectively; and the estimated 20-month extensive chronic GVHD rates were 12.5% and 16.7% (P = .718), respectively. The neutrophil engraftment time was similar in both groups [median (range), 15.0 (12.0-17.0) and 14.0 (12.0-19.0) days, respectively; P = .961]. However, ATG was more expensive than PTCy [median (range), US$4,062 (US$2,215-6,647) for ATG vs US$51.80 (US$43.20-69.20) for PTCy; P < .001]. In conclusion, PTCy and ATG afforded similar clinical outcomes after HLA-matched unrelated donor transplantation but PTCy was less expensive.

Evolution of the role of haploidentical stem cell transplantation: past, present, and future

INTRODUCTION

The accessibility to haplo-donors has led to an increase in the number of haplo-HSCT worldwide. A systematic search of the PubMed database between 2000 to present was performed.

AREAS COVERED

In this review, the authors discussed the most used approaches to perform haplo-HSCT and its results: T-cell depletion (TCD, including Perugia platform and its modifications) and T-cell repleted haplo (TCR, including the high-dose post-transplant cyclophosphamide strategy (Baltimore protocol) and the Beijing protocol). The improvements and modifications made to the different strategies have increased the indications of haplo-HSCT, including both malignant and nonmalignant disorders. Focusing on the Baltimore protocol, the authors review the results of the retrospective studies that have compared it to other donor transplants. The limitations of this strategy in terms of toxicity, graft complications, and GVHD are also discussed in detail. Finally, possible approaches to improve the outcomes of TCR haplo-HSCT are presented.

EXPERT OPINION

The recent advances in the field of haplo-HSCT have allowed a large number of patients with incurable diseases to benefit from this procedure despite not having a matched donor. With all available strategies, virtually no patient who needs an allogeneic transplant should be excluded by the absence of a donor.

Recent progress in haploidentical transplantation: is this the optimal choice for alternative donor transplantation?

PURPOSE OF REVIEW

This article is intended to review recent trends and improvements in haploidentical transplantation to understand its current status and future direction.

RECENT FINDINGS

The noninferiority of haploidentical donors compared with other donor sources, including HLA-matched related or unrelated donors, has been demonstrated in patients with various hematological diseases. The development of graft-versus-host-disease (GVHD) prophylaxis using posttransplant cyclophosphamide has effectively reduced transplant-related mortality caused by GVHD, graft rejection, and other related complications. Novel GVHD prophylactic methods and other supportive strategies are under intense investigation to reduce the risk of infections and retain graft-versus-leukemia/lymphoma effects after transplantation.

SUMMARY

Recent progress in haploidentical stem cell transplantation has broadened the availability of donor sources for patients with hematological diseases. It is important to compare and examine the impact of donor sources on transplant outcomes to achieve a better understanding about the appropriate donor choice for each patient.

Haematopoietic stem cell transplantation for inborn errors of immunity: 25-year experience from University of Malaya Medical Centre, Malaysia

AIM

Inborn errors of immunity (IEI) comprise a heterogeneous group of disorders of the immune system, most of which are curable by haematopoietic stem cell transplantation (HSCT). We present a 25-year audit of HSCT for IEI at a tertiary-level academic hospital in Malaysia.

METHODS

Review of medical records of all cases of IEI who underwent HSCT between January 1993 and December 2018 at our centre. Diagnoses, complications, HSCT protocols and outcome data were studied.

RESULTS

There were 20 patients (19 boys) with a median age at diagnosis of 11 months (range: 2 months to 12 years). Eleven of 19 (58%) had malnutrition at presentation. Donor sources were variable: 13 (65%) matched sibling donor (MSD), 4 (20%) human leukocyte antigen-haploidentical donor (HD) and 3 (15%) matched unrelated donor (MUD). Conditioning regimens were physician-dependent and adapted to each patient's clinical status. Grades III-IV acute graft-versus-host disease occurred in two of three cases who received MUD grafts, 50% in those who received HD, and 8% in the MSD group. Transplant-related mortality at day +100 was 5%. With a median follow-up of 7.5 years, 18 (90%) patients are alive and free of infections.

CONCLUSION

Outcome of HSCT for IEI in our centre is comparable with international reports. HSCT results using HD and MUD grafts are also good despite challenges from acute graft-versus-host disease, providing a feasible alternative for patients without matched donors.

Treosulfan-based reduced toxicity hematopoietic stem cell transplantation in X-linked agammaglobulinemia: A cost-effective alternative to long-term immunoglobulin replacement in developing countries

X-linked agammaglobulinemia (XLA) is a primary antibody disorder due to a mutation in the Bruton tyrosine kinase gene that requires lifelong immunoglobulin replacement resulting in a significant economic burden and treatment abandonment. Hematopoietic stem cell transplantation (HSCT) offers an alternative option for complete cure. In our series, two children with XLA underwent successful HSCT using a myeloablative conditioning with thiotepa, treosulfan, and fludarabine from a matched sibling donor. The second child had rejected his first graft following a busulfan-based regimen with resultant autologous reconstitution. At 6 months post-HSCT, serum IgG were normal, off IVIG, and had no infections. Both children after a median follow-up of 20 months have 100% chimerism. Treosulfan-based reduced toxicity myeloablative HSCT has encouraging results with a positive impact on the socioeconomics in developing countries.

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario. Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.