Alemtuzumab, Dual Graft-versus-Host Disease Prophylaxis, and Lower CD3+ T Cell Doses Equalize Rates of Acute and Chronic Graft-versus-Host Disease in Pediatric Patients Receiving Allogeneic Hematopoietic Stem Cell Transplantation with Matched Unrelated Donor Peripheral Blood Stem Cells or Bone Marrow Grafts

Data comparing hematopoietic stem cell transplantation (HSCT) using bone marrow (BM) or peripheral blood stem cell (PBSC) grafts in children after alemtuzumab-based conditioning are lacking. We investigated whether in vivo T cell depletion using alemtuzumab could reduce the risk of severe acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD) after HSCT with matched unrelated donor (MUD) BM or PBSCs. This retrospective multicenter study included 397 children (BM group, n = 202; PBSC group, n = 195) who underwent first MUD HSCT at 9 pediatric centers in the United Kingdom between 2015 and 2019. The median age at transplantation was 7.0 years (range, .1 to 19.3 years), and the median duration of follow-up was 3.1 years (range, .3 to 7.5 years). The 3-year overall survival was 81% for the entire cohort (BM group, 80%; PBSC group, 81%). The incidence of grade II-IV aGVHD was significantly higher in the PBSC group (31%) compared to the BM group (31% versus 19%; P = .003), with no difference in the incidence of grade III-IV aGVHD (BM, 7%; PBSC, 12%; P = .17). CD3+ T cell dose >5 × 108/kg and the use of PBSCs were independent predictors of grade II-IV aGVHD. When considering CD3+ T cell dose and GVHD prophylaxis, PBSC transplantation with a calcineurin inhibitor (CNI) and mycophenolate mofetil (MMF) and a CD3+ T cell dose ≤5 × 108/kg had a comparable grade II-IV aGVHD to BM transplantation plus a CNI (20% versus 18%; P = .52). PBSC transplantation was associated with a lower incidence of cGVHD compared to BM transplantation (6% versus 11%; P = .03). Within the limits of this study, we identified a potential strategy to reduce the risk of severe GVHD in pediatric PBSC recipients that includes a combination of in vivo T cell depletion using alemtuzumab and dual GVHD prophylaxis (with a CNI and MMF) and limiting the CD3+ T cell dose to ≤5 × 108/kg.

Asymptomatic immunodeficiency-associated vaccine-derived poliovirus infections in two UK children

Increasing detections of vaccine-derived poliovirus (VDPV) globally, including in countries previously declared polio free, is a public health emergency of international concern. Individuals with primary immunodeficiency (PID) can excrete polioviruses for prolonged periods, which could act as a source of cryptic transmission of viruses with potential to cause neurological disease. Here, we report on the detection of immunodeficiency-associated VDPVs (iVDPV) from two asymptomatic male PID children in the UK in 2019. The first child cleared poliovirus with increased doses of intravenous immunoglobulin, the second child following haematopoetic stem cell transplantation. We perform genetic and phenotypic characterisation of the infecting strains, demonstrating intra-host evolution and a neurovirulent phenotype in transgenic mice. Our findings highlight a pressing need to strengthen polio surveillance. Systematic collection of stool from asymptomatic PID patients who are at high risk for poliovirus excretion could improve the ability to detect and contain iVDPVs.

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.

Hypomorphic RAG deficiency: impact of disease burden on survival and thymic recovery argues for early diagnosis and HSCT

Patients with hypomorphic mutations in the RAG1 or RAG2 gene present with either Omenn syndrome or atypical combined immunodeficiency with a wide phenotypic range. Hematopoietic stem cell transplantation (HSCT) is potentially curative, but data are scarce. We report on a worldwide cohort of 60 patients with hypomorphic RAG variants who underwent HSCT, 78% of whom experienced infections (29% active at HSCT), 72% had autoimmunity, and 18% had granulomas pretransplant. These complications are frequently associated with organ damage. Eight individuals (13%) were diagnosed by newborn screening or family history. HSCT was performed at a median of 3.4 years (range 0.3-42.9 years) from matched unrelated donors, matched sibling or matched family donors, or mismatched donors in 48%, 22%, and 30% of the patients, respectively. Grafts were T-cell depleted in 15 cases (25%). Overall survival at 1 and 4 years was 77.5% and 67.5% (median follow-up of 39 months). Infection was the main cause of death. In univariable analysis, active infection, organ damage pre-HSCT, T-cell depletion of the graft, and transplant from a mismatched family donor were predictive of worse outcome, whereas organ damage and T-cell depletion remained significant in multivariable analysis (hazard ratio [HR] = 6.01, HR = 8.46, respectively). All patients diagnosed by newborn screening or family history survived. Cumulative incidences of acute and chronic graft-versus-host disease were 35% and 22%, respectively. Cumulative incidences of new-onset autoimmunity was 15%. Immune reconstitution, particularly recovery of naïve CD4+ T cells, was faster and more robust in patients transplanted before 3.5 years of age, and without organ damage. These findings support the indication for early transplantation.

Haploidentical CD3+ TCR αβ/CD19+-depleted HSCT for MHC class II deficiency and persistent SARS-CoV-2 pneumonitis

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to coronavirus disease 2019 (COVID-19), which can range from a mild illness to a severe phenotype characterized by acute respiratory distress needing mechanical ventilation. Children with combined immunodeficiencies might be unable to mount a sufficient cellular and humoral immune response against COVID-19 and have persistent disease.

Objective

Our aim was to describe a child with combined immunodeficiency and a favorable post-hematopoietic stem cell transplant (HSCT) course following a haploidentical HSCT in the presence of persistent SARS-CoV-2 infection.

Methods

A 13-month-old girl with MHC class II deficiency developed persistent pre-HSCT SARS-CoV-2 infection. Faced with a significant challenge of balancing the risk of progressive infection due to an incompetent immune system with the danger of inflammatory pneumonitis peri-immune reconstitution after HSCT, the patient's physicians performed a maternal (with a recent history of COVID-19 infection) haploidentical HSCT. The patient received regdanvimab (after stem cell infusion) and remdesivir (before and after stem cell infusion).

Results

The patient exhibited a gradual increase in her cycle threshold values, implying a reduction in viral RNA with concomitant expansion in the CD3 lymphocyte subset and clinical and radiologic improvement.

Conclusions

Combination of adoptive transfer of maternal CD45RO⁺ memory addback T lymphocytes after haploidentical HSCT and use of regdanvimab (a SARS-CoV-2-neutralizing mAb) and remdesivir may have led to the successful outcome in our patient with severe immunodeficiency after she had undergone HSCT. This case highlights the role of novel antiviral strategies (mAbs and CD45RO⁺ memory T lymphocytes) in contributing to viral clearance in a challenging clinical scenario.

BCG lymphadenitis: a potential complication of immune reconstitution following haematopoietic stem cell transplant

An MHC class II deficient 2-year-old boy presented with fever and an enlarging left neck mass 100 days post allogeneic haematopoietic stem cell transplant (HSCT). Fever persisted despite treatment with broad-spectrum β-lactam antibiotics. His BCG vaccination site at presentation was quiescent. Ultrasound showed enlarged cervical lymph nodes. An incisional biopsy of the large nodal mass yielded acid-fast bacilli, identified as Mycobacterium bovis by genome sequencing. Treatment with rifampicin, isoniazid and pyridoxine was started. The mass suppurated (figure 1), before healing concurrently with T-lymphocyte reconstitution at approximately day 130 post-HSCT.

T-replete HLA-matched grafts vs T-depleted HLA-mismatched grafts in inborn errors of immunity

Hematopoietic cell transplantation (HCT) has become standard-of-care for an increasing number of inborn errors of immunity (IEI). This report is the first to compare transplant outcomes according to T-cell-replete (ie, T-replete) HLA-matched grafts using alemtuzumab (n = 117) and T-cell-depleted (ie, T-depleted) HLA-mismatched grafts using T-cell receptor-αβ (TCRαβ)/CD19 depletion (n = 47) in children with IEI who underwent first HCT between 2014 and 2019. All patients received treosulfan-based conditioning except patients with DNA repair disorders. For T-replete grafts, the stem cell source was marrow in 25 (21%) patients, peripheral blood stem cell (PBSC) in 85 (73%), and cord blood in 7 (6%). TCRαβ/CD19 depletion was performed on PBSCs from 45 haploidentical parental donors and 2 mismatched unrelated donors. The 3-year overall survival (OS) and event-free survival for the entire cohort were 85% (77%-90%) and 79% (69%-86%), respectively. Analysis according to age at transplant revealed a comparable 3-year OS between T-replete grafts (88%; 76%-94%) and T-depleted grafts (87%; 64%-96%) in younger patients (aged <5 years at HCT). For older patients (aged >5 years), the OS was significantly lower in T-depleted grafts (55%; 23%-78%) compared with T-replete grafts (87%; 68%-95%) (P = .03). Grade III to IV acute graft-versus-host disease was observed in 8% of T-replete marrow, 7% of T-replete PBSC, 14% of T-replete cord blood, and 2% of T-depleted PBSC (P = .73). Higher incidence of viremia (P < .001) and delayed CD3 reconstitution (P = .003) were observed after T-depleted graft HCT. These data indicate that mismatched donor transplant after TCRαβ/CD19 depletion represents an excellent alternative for younger children with IEI in need of an allograft.

Hematopoietic cell transplantation in severe combined immunodeficiency: The SCETIDE 2006-2014 European cohort

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) represents a curative treatment for patients with severe combined immunodeficiency (SCID), a group of monogenic immune disorders with an otherwise fatal outcome.

OBJECTIVE

We performed a comprehensive multicenter analysis of genotype-specific HSCT outcome, including detailed analysis of immune reconstitution (IR) and the predictive value for clinical outcome.

METHODS

HSCT outcome was studied in 338 patients with genetically confirmed SCID who underwent transplantation in 2006-2014 and who were registered in the SCETIDE registry. In a representative subgroup of 152 patients, data on IR and long-term clinical outcome were analyzed.

RESULTS

Two-year OS was similar with matched family and unrelated donors and better than mismatched donor HSCT (P < .001). The 2-year event-free survival (EFS) was similar in matched and mismatched unrelated donor and less favorable in mismatched related donor (MMRD) HSCT (P < .001). Genetic subgroups did not differ in 2-year OS (P = .1) and EFS (P = .073). In multivariate analysis, pretransplantation infections and use of MMRDs were associated with less favorable OS and EFS. With a median follow-up of 6.2 years (range, 2.0-11.8 years), 73 of 152 patients in the IR cohort were alive and well without Ig dependency. IL-2 receptor gamma chain/Janus kinase 3/IL-7 receptor-deficient SCID, myeloablative conditioning, matched donor HSCT, and naive CD4 T lymphocytes >0.5 × 10^e3/μL at +1 year were identified as independent predictors of favorable clinical and immunologic outcome.

CONCLUSION

Recent advances in HSCT in SCID patients have resulted in improved OS and EFS in all genotypes and donor types. To achieve a favorable long-term outcome, treatment strategies should aim for optimal naive CD4 T lymphocyte regeneration.

Simple Measurement of IgA Predicts Immunity and Mortality in Ataxia-Telangiectasia

Patients with ataxia-telangiectasia (A-T) suffer from progressive cerebellar ataxia, immunodeficiency, respiratory failure, and cancer susceptibility. From a clinical point of view, A-T patients with IgA deficiency show more symptoms and may have a poorer prognosis. In this study, we analyzed mortality and immunity data of 659 A-T patients with regard to IgA deficiency collected from the European Society for Immunodeficiencies (ESID) registry and from 66 patients with classical A-T who attended at the Frankfurt Goethe-University between 2012 and 2018. We studied peripheral B- and T-cell subsets and T-cell repertoire of the Frankfurt cohort and survival rates of all A-T patients in the ESID registry. Patients with A-T have significant alterations in their lymphocyte phenotypes. All subsets (CD3, CD4, CD8, CD19, CD4/CD45RA, and CD8/CD45RA) were significantly diminished compared to standard values. Patients with IgA deficiency (n = 35) had significantly lower lymphocyte counts compared to A-T patients without IgA deficiency (n = 31) due to a further decrease of naïve CD4 T-cells, central memory CD4 cells, and regulatory T-cells. Although both patient groups showed affected TCR-ß repertoires compared to controls, no differences could be detected between patients with and without IgA deficiency. Overall survival of patients with IgA deficiency was significantly diminished. For the first time, our data show that patients with IgA deficiency have significantly lower lymphocyte counts and subsets, which are accompanied with reduced survival, compared to A-T patients without IgA deficiency. IgA, a simple surrogate marker, is indicating the poorest prognosis for classical A-T patients. Both non-interventional clinical trials were registered at clinicaltrials.gov 2012 (Susceptibility to infections in ataxia-telangiectasia; NCT02345135) and 2017 (Susceptibility to Infections, tumor risk and liver disease in patients with ataxia-telangiectasia; NCT03357978)

International retrospective study of allogeneic hematopoietic cell transplantation for activated PI3K-delta syndrome

Background:

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a combined immunodeficiency with a heterogeneous phenotype considered reversible by allogeneic hematopoietic cell transplantation (HCT).

Objectives:

This study sought to characterize HCT outcomes in APDS.

Methods:

Retrospective data were collected on 57 patients with APDS1/2 (median age, 13 years; range, 2–66 years) who underwent HCT.

Results:

Pre-HCT comorbidities such as lung, gastrointestinal, and liver pathology were common, with hematologic malignancy in 26%. With median follow-up of 2.3 years, 2-year overall and graft failure–free survival probabilities were 86% and 68%, respectively, and did not differ significantly by APDS1 versus APDS2, donor type, or conditioning intensity. The 2-year cumulative incidence of graft failure following first HCT was 17% overall but 42% if mammalian target of rapamycin inhibitor(s) (mTORi) were used in the first year post-HCT, compared with 9% without mTORi. Similarly, 2-year cumulative incidence of unplanned donor cell infusion was overall 28%, but 65% in the context of mTORi receipt and 23% without. Phenotype reversal occurred in 96% of evaluable patients, of whom 17% had mixed chimerism. Vulnerability to renal complications continued post-HCT, adding new insights into potential nonimmunologic roles of phosphoinositide 3-kinase not correctable through HCT.

Conclusions:

Graft failure, graft instability, and poor graft function requiring unplanned donor cell infusion were major barriers to successful HCT. Post-HCT mTORi use may confer an advantage to residual host cells, promoting graft instability. Longer-term post-HCT follow-up of more patients is needed to elucidate the kinetics of immune reconstitution and donor chimerism, establish approaches that reduce graft instability, and assess the completeness of phenotype reversal over time.

A survey of extracorporeal photopheresis treatment in pediatric patients in the United Kingdom

Extracorporeal photopheresis (ECP) is a second‐line therapy in acute and chronic GVHD and solid organ transplant rejection. We report ECP use in 98 pediatric patients in seven UK centers from 2010 to 2017, the majority treated for aGVHD (73.5%). ECP was safe and well tolerated including in low body weight patients. Most patients were on multiple immunosuppressive therapies prior to ECP; 45.9% were able to reduce or stop immunosuppression with treatment. Complete or partial response was reported in almost 60%. This study supports the need to include ECP treatment data to national transplant databases to provide accurate information regarding service provision, patient outcomes, and safety.

Outcome of autoimmune cytopenia after hematopoietic cell transplantation in primary immunodeficiency

BACKGROUND

Post hematopoietic cell transplantation (HCT) autoimmune cytopenia (AIC) is a potentially life-threatening complication, but studies focusing on large cohorts of patients transplanted for primary immunodeficiency are lacking.

OBJECTIVES

This study sought to determine the incidence, risk factors, and outcomes of post-HCT AIC and B-lymphocyte function following rituximab.

METHODS

We retrospectively studied 502 children with primary immunodeficiency who were transplanted at our center between 1987 and 2018.

RESULTS

Thirty-six patients (9%) developed post-HCT AIC, with a median onset of 6.5 months post-HCT. On univariate analysis, pre-HCT AIC, mismatched donor, alemtuzumab, anti-thymocyte antiglobulin, and acute and chronic graft versus host disease were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (subdistribution hazard ratio, 9.0; 95% CI, 1.50-54.0; P = .02) was independently associated with post-HCT AIC. Corticosteroid and high-dose intravenous immunoglobulin achieved remission in 50% (n = 18), additional rituximab led to remission in 25% (n = 9), and the remaining 25% were treated with a combination of various modalities including sirolimus (n = 5), bortezomib (n = 3), mycophenolate mofetil (n = 2), splenectomy (n = 2), and second HCT (n = 3). The mortality of post-HCT AIC reduced from 25% (4 of 16) prior to 2011 to 5% (1 of 20) after 2011. The median follow-up of 5.8 years (range, 0.4 to 29.1 years) showed that 26 of 30 survivors (87%) were in complete remission, and 4 were in remission with ongoing sirolimus and low-dose steroids. Of the 17 who received rituximab, 7 had B-lymphocyte recovery, 5 had persistent low B-lymphocyte count and remained on intravenous immunoglobulin replacement, 2 had second HCT, and 3 died.

CONCLUSIONS

The frequency of post HCT AIC in our cohort was 9%, and the most significant risk factors for its occurrence were the presence of graft versus host disease and the use of alemtuzumab.

Hematopoietic Cell Transplantation in Patients With Primary Immune Regulatory Disorders (PIRD): A Primary Immune Deficiency Treatment Consortium (PIDTC) Survey

Primary Immune Regulatory Disorders (PIRD) are an expanding group of diseases caused by gene defects in several different immune pathways, such as regulatory T cell function. Patients with PIRD develop clinical manifestations associated with diminished and exaggerated immune responses. Management of these patients is complicated; oftentimes immunosuppressive therapies are insufficient, and patients may require hematopoietic cell transplant (HCT) for treatment. Analysis of HCT data in PIRD patients have previously focused on a single gene defect. This study surveyed transplanted patients with a phenotypic clinical picture consistent with PIRD treated in 33 Primary Immune Deficiency Treatment Consortium centers and European centers. Our data showed that PIRD patients often had immunodeficient and autoimmune features affecting multiple organ systems. Transplantation resulted in resolution of disease manifestations in more than half of the patients with an overall 5-years survival of 67%. This study, the first to encompass disorders across the PIRD spectrum, highlights the need for further research in PIRD management.

Proposed Therapeutic Range of Treosulfan in Reduced Toxicity Pediatric Allogeneic Hematopoietic Stem Cell Transplant Conditioning: Results From a Prospective Trial

Treosulfan is given off‐label in pediatric allogeneic hematopoietic stem cell transplant. This study investigated treosulfan's pharmacokinetics (PKs), efficacy, and safety in a prospective trial. Pediatric patients (n = 87) receiving treosulfan‐fludarabine conditioning were followed for at least 1 year posttransplant. PKs were described with a two‐compartment model. During follow‐up, 11 of 87 patients died and 12 of 87 patients had low engraftment (≤ 20% myeloid chimerism). For each increase in treosulfan area under the curve from zero to infinity (AUC_(0‐∞)) of 1,000 mg hour/L the hazard ratio (95% confidence interval) for mortality increase was 1.46 (1.23–1.74), and the hazard ratio for low engraftment was 0.61 (0.36–1.04). A cumulative AUC_(0‐∞) of 4,800 mg hour/L maximized the probability of success (> 20% engraftment and no mortality) at 82%. Probability of success with AUC_(0‐∞) between 80% and 125% of this target were 78% and 79%. Measuring PK at the first dose and individualizing the third dose may be required in nonmalignant disease.

The United Kingdom Primary Immune Deficiency (UKPID) registry 2012 to 2017

This is the second report of the United Kingdom Primary Immunodeficiency (UKPID) registry. The registry will be a decade old in 2018 and, as of August 2017, had recruited 4758 patients encompassing 97% of immunology centres within the United Kingdom. This represents a doubling of recruitment into the registry since we reported on 2229 patients included in our first report of 2013. Minimum PID prevalence in the United Kingdom is currently 5·90/100 000 and an average incidence of PID between 1980 and 2000 of 7·6 cases per 100 000 UK live births. Data are presented on the frequency of diseases recorded, disease prevalence, diagnostic delay and treatment modality, including haematopoietic stem cell transplantation (HSCT) and gene therapy. The registry provides valuable information to clinicians, researchers, service commissioners and industry alike on PID within the United Kingdom, which may not otherwise be available without the existence of a well-established registry.

New graft manipulation strategies improve the outcome of mismatched stem cell transplantation in children with primary immunodeficiencies

BACKGROUND

Mismatched stem cell transplantation is associated with a high risk of graft loss, graft-versus-host disease (GvHD), and transplant-related mortality. Alternative graft manipulation strategies have been used over the last 11 years to reduce these risks.

OBJECTIVE

We investigated the outcome of using different graft manipulation strategies among children with primary immunodeficiencies.

METHODS

Between 2006 and 2017, 147 patients with primary immunodeficiencies received 155 mismatched grafts: 30 T-cell receptor (TCR) αβ/CD19-depleted grafts, 43 cord blood (CB) grafts (72% with no serotherapy), 17 CD34⁺ selection with T-cell add-back grafts, and 65 unmanipulated grafts.

RESULTS

The estimated 8-year survival of the entire cohort was 79%, transplant-related mortality was 21.7%, and the graft failure rate was 6.7%. Posttransplantation viral reactivation, grade II to IV acute graft-versus-host disease (aGvHD), and chronic graft-versus-host disease (cGvHD) complicated 49.6%, 35%, and 15% of transplantations, respectively. Use of TCRαβ/CD19 depletion was associated with a significantly lower incidence of grade II to IV aGvHD (11.5%) and cGvHD (0%), although with a greater incidence of viral reactivation (70%) in comparison with other grafts. T-cell immune reconstitution was robust among CB transplants, although with a high incidence (56.7%) of grade II to IV aGvHD. Stable full donor engraftment was significantly greater at 80% among TCRαβ⁺/CD19⁺-depleted and CB transplants versus 40% to 60% among the other groups.

CONCLUSIONS

Rapidly accessible CB and haploidentical grafts are suitable alternatives for patients with no HLA-matched donor. Cord transplantation without serotherapy and TCRαβ⁺/CD19⁺-depleted grafts produced comparable survival rates of around 80%, although with a high rate of aGvHD with the former and a high risk of viral reactivation with the latter that need to be addressed.

Phenotype, penetrance, and treatment of 133 cytotoxic T-lymphocyte antigen 4-insufficient subjects

BACKGROUND

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative immune regulator. Heterozygous CTLA4 germline mutations can cause a complex immune dysregulation syndrome in human subjects.

OBJECTIVE

We sought to characterize the penetrance, clinical features, and best treatment options in 133 CTLA4 mutation carriers.

METHODS

Genetics, clinical features, laboratory values, and outcomes of treatment options were assessed in a worldwide cohort of CTLA4 mutation carriers.

RESULTS

We identified 133 subjects from 54 unrelated families carrying 45 different heterozygous CTLA4 mutations, including 28 previously undescribed mutations. Ninety mutation carriers were considered affected, suggesting a clinical penetrance of at least 67%; median age of onset was 11 years, and the mortality rate within affected mutation carriers was 16% (n = 15). Main clinical manifestations included hypogammaglobulinemia (84%), lymphoproliferation (73%), autoimmune cytopenia (62%), and respiratory (68%), gastrointestinal (59%), or neurological features (29%). Eight affected mutation carriers had lymphoma, and 3 had gastric cancer. An EBV association was found in 6 patients with malignancies. CTLA4 mutations were associated with lymphopenia and decreased T-, B-, and natural killer (NK) cell counts. Successful targeted therapies included application of CTLA-4 fusion proteins, mechanistic target of rapamycin inhibitors, and hematopoietic stem cell transplantation. EBV reactivation occurred in 2 affected mutation carriers after immunosuppression.

CONCLUSIONS

Affected mutation carriers with CTLA-4 insufficiency can present in any medical specialty. Family members should be counseled because disease manifestation can occur as late as 50 years of age. EBV- and cytomegalovirus-associated complications must be closely monitored. Treatment interventions should be coordinated in clinical trials.

High transplant-related mortality associated with haematopoietic stem cell transplantation for paediatric therapy-related acute myeloid leukaemia (t-AML). A study on behalf of the United Kingdom Paediatric Blood and Bone Marrow Transplant Group

Paediatric therapy-related acute myeloid leukaemia (t-AML) is rare and the outcome is poor. While allogeneic haematopoietic stem cell transplantation (HSCT) is generally the accepted modality of treatment, data regarding salvage chemotherapy, remission induction, conditioning regimens, transplant-related mortality and outcome is scarce. Between 2000 and2016, 36 children with t-AML were treated in seven UK paediatric HSCT centres. The most common salvage protocol for remission induction was FLAG with or without idarubicin and 28 patients were in complete morphological remission prior to BMT. Only 12 patients survived (33%). Transplant-related mortality (TRM) was the leading cause of death.

Disease Evolution and Response to Rapamycin in Activated Phosphoinositide 3-Kinase δ Syndrome: The European Society for Immunodeficiencies-Activated Phosphoinositide 3-Kinase δ Syndrome Registry

Activated phosphoinositide 3-kinase (PI3K) δ Syndrome (APDS), caused by autosomal dominant mutations in PIK3CD (APDS1) or PIK3R1 (APDS2), is a heterogeneous primary immunodeficiency. While initial cohort-descriptions summarized the spectrum of clinical and immunological manifestations, questions about long-term disease evolution and response to therapy remain. The prospective European Society for Immunodeficiencies (ESID)-APDS registry aims to characterize the disease course, identify outcome predictors, and evaluate treatment responses. So far, 77 patients have been recruited (51 APDS1, 26 APDS2). Analysis of disease evolution in the first 68 patients pinpoints the early occurrence of recurrent respiratory infections followed by chronic lymphoproliferation, gastrointestinal manifestations, and cytopenias. Although most manifestations occur by age 15, adult-onset and asymptomatic courses were documented. Bronchiectasis was observed in 24/40 APDS1 patients who received a CT-scan compared with 4/15 APDS2 patients. By age 20, half of the patients had received at least one immunosuppressant, but 2-3 lines of immunosuppressive therapy were not unusual before age 10. Response to rapamycin was rated by physician visual analog scale as good in 10, moderate in 9, and poor in 7. Lymphoproliferation showed the best response (8 complete, 11 partial, 6 no remission), while bowel inflammation (3 complete, 3 partial, 9 no remission) and cytopenia (3 complete, 2 partial, 9 no remission) responded less well. Hence, non-lymphoproliferative manifestations should be a key target for novel therapies. This report from the ESID-APDS registry provides comprehensive baseline documentation for a growing cohort that will be followed prospectively to establish prognostic factors and identify patients for treatment studies.

T-cell receptor αβ+ and CD19+ cell-depleted haploidentical and mismatched hematopoietic stem cell transplantation in primary immune deficiency

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is used as a therapeutic approach for primary immunodeficiencies (PIDs). The best outcomes have been achieved with HLA-matched donors, but when a matched donor is not available, a haploidentical or mismatched unrelated donor (mMUD) can be useful. Various strategies are used to mitigate the risk of graft-versus-host disease (GvHD) and rejection associated with such transplants.

OBJECTIVE

We sought to evaluate the outcomes of haploidentical or mMUD HSCT after depleting GvHD-causing T-cell receptor (TCR) αβ CD3⁺ cells from the graft.

METHODS

CD3⁺TCRαβ⁺/CD19⁺ depleted grafts were given in conditioned (except 3) children with PIDs. Treosulfan (busulfan in 1 patient), fludarabine, thiotepa, and anti-thymocyte globulin or alemtuzumab conditioning were used in 77% of cases, and all but 4 received GvHD prophylaxis.

RESULTS

Twenty-five patients with 12 types of PIDs received 26 HSCTs. Three underwent transplantation for refractory GvHD that developed after the first cord transplantation. At a median follow-up of 20.8 months (range, 5 month-3.3 years), 21 of 25 patients survived and were cured of underlying immunodeficiency. Overall and event-free survival at 3 years were 83.9% and 80.4%, respectively. Cumulative incidence of grade II to IV acute GvHD was 22% ± 8.7%. No case of visceral or chronic GvHD was seen. Cumulative incidences of graft failure, cytomegalovirus, and/or adenoviral infections and transplant-related mortality at 1 year were 4.2% ± 4.1%, 58.8% ± 9.8%, and 16.1% ± 7.4%, respectively. Patients undergoing transplantation with systemic viral infections had poor survival in comparison with those with absent or resolved infections (33.3% vs 100%).

CONCLUSION

CD3⁺TCRαβ⁺ and CD19⁺ cell-depleted haploidentical or mMUD HSCT is a practical and viable alternative for children with a range of PIDs.

Recommendations for Screening and Management of Late Effects in Patients with Severe Combined Immunodeficiency after Allogenic Hematopoietic Cell Transplantation: A Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric HCT

Severe combined immunodeficiency (SCID) is effectively treated with hematopoietic cell transplantation (HCT), with overall survival approaching 90% in contemporary reports. However, survivors are at risk for developing late complications because of the variable durability of high-quality immune function, underlying genotype of SCID, comorbidities due to infections in the pretransplantation and post-transplantation periods, and use of conditioning before transplantation. An international group of transplantation experts was convened in 2016 to review the current knowledge of late effects seen in SCID patients after HCT and to develop recommendations for screening and monitoring for late effects. This report provides recommendations for screening and management of pediatric and adult SCID patients treated with HCT.

Hematopoietic stem cell transplantation in patients with gain-of-function signal transducer and activator of transcription 1 mutations

BACKGROUND

Gain-of-function (GOF) mutations in signal transducer and activator of transcription 1 (STAT1) cause susceptibility to a range of infections, autoimmunity, immune dysregulation, and combined immunodeficiency. Disease manifestations can be mild or severe and life-threatening. Hematopoietic stem cell transplantation (HSCT) has been used in some patients with more severe symptoms to treat and cure the disorder. However, the outcome of HSCT for this disorder is not well established.

OBJECTIVE

We sought to aggregate the worldwide experience of HSCT in patients with GOF-STAT1 mutations and to assess outcomes, including donor engraftment, overall survival, graft-versus-host disease, and transplant-related complications.

METHODS

Data were collected from an international cohort of 15 patients with GOF-STAT1 mutations who had undergone HSCT using a variety of conditioning regimens and donor sources. Retrospective data collection allowed the outcome of transplantation to be assessed. In vitro functional testing was performed to confirm that each of the identified STAT1 variants was in fact a GOF mutation.

RESULTS

Primary donor engraftment in this cohort of 15 patients with GOF-STAT1 mutations was 74%, and overall survival was only 40%. Secondary graft failure was common (50%), and posttransplantation event-free survival was poor (10% by 100 days). A subset of patients had hemophagocytic lymphohistiocytosis before transplant, contributing to their poor outcomes.

CONCLUSION

Our data indicate that HSCT for patients with GOF-STAT1 mutations is curative but has significant risk of secondary graft failure and death.

Current Knowledge and Priorities for Future Research in Late Effects after Hematopoietic Stem Cell Transplantation (HCT) for Severe Combined Immunodeficiency Patients: A Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric HCT

Severe combined immunodeficiency (SCID) is 1 of the most common indications for pediatric hematopoietic cell transplantation (HCT) in patients with primary immunodeficiency. Historically, SCID was diagnosed in infants who presented with opportunistic infections within the first year of life. With newborn screening (NBS) for SCID in most of the United States, the majority of infants with SCID are now diagnosed and treated in the first 3.5 months of life; however, in the rest of the world, the lack of NBS means that most infants with SCID still present with infections. The average survival for SCID patients who have undergone transplantation currently is >70% at 3 years after transplantation, although this can vary significantly based on multiple factors, including age and infection status at the time of transplantation, type of donor source utilized, manipulation of graft before transplantation, graft-versus-host disease prophylaxis, type of conditioning (if any) utilized, and underlying genotype of SCID. In at least 1 study of SCID patients who received no conditioning, long-term survival was 77% at 8.7 years (range out to 26 years) after transplantation. Although a majority of patients with SCID will engraft T cells without any conditioning therapy, depending on genotype, donor source, HLA match, and presence of circulating maternal cells, a sizable percentage of these will fail to achieve full immune reconstitution. Without conditioning, T cell reconstitution typically occurs, although not always fully, whereas B cell engraftment does not, leaving some molecular types of SCID patients with intrinsically defective B cells, in most cases, dependent on regular infusions of immunoglobulin. Because of this, many centers have used conditioning with alkylating agents including busulfan or melphalan known to open marrow niches in attempts to achieve B cell reconstitution. Thus, it is imperative that we understand the potential late effects of these agents in this patient population. There are also nonimmunologic risks associated with HCT for SCID that appear to be dependent upon the genotype of the patient. In this report, we have evaluated the published data on late effects and attempted to summarize the known risks associated with conditioning and alternative donor sources. These data, while informative, are also a clear demonstration that there is still much to be learned from the SCID population in terms of their post-HCT outcomes. This paper will summarize current findings and recommend further research in areas considered high priority. Specific guidelines regarding a recommended approach to long-term follow-up, including laboratory and clinical monitoring, will be forthcoming in a subsequent paper.

Long-term outcomes of 176 patients with X-linked hyper-IgM syndrome treated with or without hematopoietic cell transplantation

BACKGROUND

X-linked hyper-IgM syndrome (XHIGM) is a primary immunodeficiency with high morbidity and mortality compared with those seen in healthy subjects. Hematopoietic cell transplantation (HCT) has been considered a curative therapy, but the procedure has inherent complications and might not be available for all patients.

OBJECTIVES

We sought to collect data on the clinical presentation, treatment, and follow-up of a large sample of patients with XHIGM to (1) compare long-term overall survival and general well-being of patients treated with or without HCT along with clinical factors associated with mortality and (2) summarize clinical practice and risk factors in the subgroup of patients treated with HCT.

METHODS

Physicians caring for patients with primary immunodeficiency diseases were identified through the Jeffrey Modell Foundation, United States Immunodeficiency Network, Latin American Society for Immunodeficiency, and Primary Immune Deficiency Treatment Consortium. Data were collected with a Research Electronic Data Capture Web application. Survival from time of diagnosis or transplantation was estimated by using the Kaplan-Meier method compared with log-rank tests and modeled by using proportional hazards regression.

RESULTS

Twenty-eight clinical sites provided data on 189 patients given a diagnosis of XHIGM between 1964 and 2013; 176 had valid follow-up and vital status information. Sixty-seven (38%) patients received HCT. The average follow-up time was 8.5 ± 7.2 years (range, 0.1-36.2 years). No difference in overall survival was observed between patients treated with or without HCT (P = .671). However, risk associated with HCT decreased for diagnosis years 1987-1995; the hazard ratio was significantly less than 1 for diagnosis years 1995-1999. Liver disease was a significant predictor of overall survival (hazard ratio, 4.9; 95% confidence limits, 2.2-10.8; P < .001). Among survivors, those treated with HCT had higher median Karnofsky/Lansky scores than those treated without HCT (P < .001). Among patients receiving HCT, 27 (40%) had graft-versus-host disease, and most deaths occurred within 1 year of transplantation.

CONCLUSION

No difference in survival was observed between patients treated with or without HCT across all diagnosis years (1964-2013). However, survivors treated with HCT experienced somewhat greater well-being, and hazards associated with HCT decreased, reaching levels of significantly less risk in the late 1990s. Among patients treated with HCT, treatment at an early age is associated with improved survival. Optimism remains guarded as additional evidence accumulates.

European Society for Blood and Marrow Transplantation Analysis of Treosulfan Conditioning Before Hematopoietic Stem Cell Transplantation in Children and Adolescents With Hematological Malignancies

BACKGROUND

Standard myeloablative conditioning regimens for children with hematological malignancies undergoing allogeneic HSCT are based mainly on total body irradiation or busulfan. Their serious short- and long-term side effects warranted the exploration of less toxic alternatives. Treosulfan is increasingly used for adults and children before HSCT due to its potent immunosuppressive and cytotoxic effects combined with low organ toxicity.

PROCEDURE

To further investigate the role of treosulfan conditioning in children, the EBMT Pediatric diseases working party performed a retrospective analysis of 193 children with hematological malignancies (ALL n = 71, AML n = 47, MDS/MPS n = 40, other leukemia/lymphoma n = 25) undergoing allogeneic HSCT following treosulfan between January 2005 and July 2010.

RESULTS

Early regimen-related toxicity was low and mainly gastrointestinal. Veno-occlusive disease and neurological toxicity were rare. There was no association of toxicity with type of disease or treosulfan dose. High-grade early toxicity was not higher in infants or patients undergoing second or later transplantation. Treatment related mortality was low at 14%. Three-year event-free survival was 45 ± 4% and not significantly influenced by number of transplants, however it appeared to be significantly better for infants (P = 0.022). When compared to treosulfan plus fludarabine, the combination of treosulfan, fludarabine and an alkylator (either thiotepa or melphalan) resulted in significantly better overall survival (OS, P = 0.048) and a trend toward better EFS.

CONCLUSIONS

Treosulfan based conditioning is a safe and effective approach for children with hematological malignancies, including and importantly for infants and those patients undergoing second or later transplantation.

Recent advances in the management of graft-versus-host disease

Graft-versus-host disease (GvHD) remains a significant hurdle in overcoming the morbidity and mortality associated with haemopoietic stem cell transplantation in children. Better understanding of its pathobiology is facilitating the development of biomarkers for the severity of acute GvHD and treatment response, and has led to the introduction of a more prognostically relevant grading system for chronic GvHD. These enable stratification of appropriate prophylactic and treatment strategies according to the risk profiles of individual patients. Steroid-refractory acute GvHD has a poor prognosis, but early reports of the use of new immunosuppressive drugs and especially cellular treatments with extracorporeal photopheresis and mesenchymal stem cells suggest improved short-term outcomes and offer the promise of increased longer-term survival rates.

Host natural killer immunity is a key indicator of permissiveness for donor cell engraftment in patients with severe combined immunodeficiency

Background

Severe combined immunodeficiency (SCID) can be cured by using allogeneic hematopoietic stem cell transplantation, and the absence of host immunity often obviates the need for preconditioning. Depending on the underlying genetic defect and when blocks in differentiation occur during lymphocyte ontogeny, infants with SCID have absent or greatly reduced numbers of functional T cells. Natural killer (NK) cell populations are usually absent in the SCID-X1 and Janus kinase 3 forms of SCID and greatly reduced in adenosine deaminase deficiency SCID but often present in other forms of the disorder.

Objective

To determine if SCID phenotypes indicate host permissiveness to donor cell engraftment.

Methods

A retrospective data analysis considered whether host NK cells influenced donor T-cell engraftment, immune reconstitution, and long-term outcomes in children who had undergone nonconditioned allogeneic stem cell transplantation between 1990 and 2011 in the United Kingdom. Detailed analysis of T- and B-cell immune reconstitution and donor chimerism was compared between the NK⁺ (n = 24) and NK⁻ (n = 53) forms of SCID.

Results

Overall, 77 children underwent transplantation, with survival of 90% in matched sibling donor/matched family donor transplants compared with 60% when alternative donors were used. Infants with NK⁻SCID were more likely to survive than NK⁺ recipients (87% vs 62%, P < .01) and had high-level donor T-cell chimerism with superior long-term recovery of CD4 T-cell immunity. Notably, 33% of children with NK⁺SCID required additional transplantation procedures compared with only 8% of children with NK⁻SCID (P < .005).

Conclusions

NK⁻SCID disorders are highly permissive for donor T-cell engraftment without preconditioning, whereas the presence of NK cells is a strong indicator that preparative conditioning is required for engraftment of T-cell precursors capable of supporting robust T-cell reconstitution.

The United Kingdom Primary Immune Deficiency (UKPID) Registry: report of the first 4 years' activity 2008-2012

This report summarizes the establishment of the first national online registry of primary immune deficency in the United Kingdom, the United Kingdom Primary Immunodeficiency (UKPID Registry). This UKPID Registry is based on the European Society for Immune Deficiency (ESID) registry platform, hosted on servers at the Royal Free site of University College, London. It is accessible to users through the website of the United Kingdom Primary Immunodeficiency Network (www.ukpin.org.uk). Twenty-seven centres in the United Kingdom are actively contributing data, with an additional nine centres completing their ethical and governance approvals to participate. This indicates that 36 of 38 (95%) of recognized centres in the United Kingdom have engaged with this project. To date, 2229 patients have been enrolled, with a notable increasing rate of recruitment in the past 12 months. Data are presented on the range of diagnoses recorded, estimated minimum disease prevalence, geographical distribution of patients across the United Kingdom, age at presentation, diagnostic delay, treatment modalities used and evidence of their monitoring and effectiveness.