Long-Term Immune Recovery After Hematopoietic Stem Cell Transplantation for ADA Deficiency: a Single-Center Experience

Successful Immune Reconstitution in a Patient with a TYK2 Deficiency after Allogeneic Stem Cell Transplantation from Unrelated Donors

A boy with primary immunodeficiency, caused by a tyrosine kinase 2 (TYK2) mutation, presented with immune defects and a lifelong history of severe infections. Our aim was to determine whether allogeneic hematopoietic stem cell transplantation (HSCT) could restore the patient's immune defenses and reduce susceptibility to infection. In the absence of a suitable HLA-matched blood relative to act as a donor, the patient received an allogeneic HSCT from unrelated donors. The patient's clinical data were analyzed in the Children's Hospital of Chongqing Medical University (Chongqing, China) before transplantation and during the 4-year follow-up period using a combination of western blotting (e.g., TYK2 and STAT levels), qRT-PCR (e.g., T cell receptor rearrangement excision circles, kappa deletion element recombination circles, and TYK2 transcript levels), and flow cytometry (e.g., lymphocyte subpopulations and CD107α secretion). We found that HSCT significantly reduced the incidence of severe infections, restored normal TKY2 levels, and reversed defects such as impaired JAK/STAT signaling in response to interferon-α or interleukin-10 treatment. Although the patient did not develop acute graft-versus-host disease (GVHD) after transplantation, he did experience chronic GVHD symptoms in a number of organs, which were effectively managed. Our findings suggest that HSCT is a feasible strategy for reconstituting the immune system in TYK2-deficient patients; however, the factors associated with GVHD and autoimmune thyroiditis development in TYK2-deficient patients undergoing HSCT warrant further investigation.

Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency

Adenosine deaminase (ADA) deficiency leads to severe combined immunodeficiency (SCID). Previous clinical trials showed that autologous CD34+ cell gene therapy (GT) following busulfan reduced-intensity conditioning is a promising therapeutic approach for ADA-SCID, but long-term data are warranted. Here we report an analysis on long-term safety and efficacy data of 43 patients with ADA-SCID who received retroviral ex vivo bone marrow-derived hematopoietic stem cell GT. Twenty-two individuals (median follow-up 15.4 years) were treated in the context of clinical development or named patient program. Nineteen patients were treated post-marketing authorization (median follow-up 3.2 years), and two additional patients received mobilized peripheral blood CD34+ cell GT. At data cutoff, all 43 patients were alive, with a median follow-up of 5.0 years (interquartile range 2.4-15.4) and 2 years intervention-free survival (no need for long-term enzyme replacement therapy or allogeneic hematopoietic stem cell transplantation) of 88% (95% confidence interval 78.7-98.4%). Most adverse events/reactions were related to disease background, busulfan conditioning or immune reconstitution; the safety profile of the real world experience was in line with premarketing cohort. One patient from the named patient program developed a T cell leukemia related to treatment 4.7 years after GT and is currently in remission. Long-term persistence of multilineage gene-corrected cells, metabolic detoxification, immune reconstitution and decreased infection rates were observed. Estimated mixed-effects models showed that higher dose of CD34+ cells infused and younger age at GT affected positively the plateau of CD3+ transduced cells, lymphocytes and CD4+ CD45RA+ naive T cells, whereas the cell dose positively influenced the final plateau of CD15+ transduced cells. These long-term data suggest that the risk-benefit of GT in ADA remains favorable and warrant for continuing long-term safety monitoring. Clinical trial registration: NCT00598481 , NCT03478670 .

Stem cell-conditioned medium is a promising treatment for Alzheimer's disease

BACKGROUND AND AIM

Alzheimer's disease (AD), a prevalent progressive neurodegenerative disease, is mainly characterized by dementia, memory loss, and cognitive disorder. Rising research was performed to develop pharmacological or non-pharmacological approaches to treat or improve AD complications. Mesenchymal stem cells (MSCs) are stromal cells that can self-renew and exhibit multilineage differentiation. Recent evidence suggested that some of the therapeutic effects of MSCs are mediated by the secreted paracrine factors. These paracrine factors, called MSC- conditioned medium (MSC-CM), may stimulate endogenous repair, promote angio- and artery genesis, and reduce apoptosis through paracrine mechanisms. The current study aims to systematically review the advantages of MSC-CM to the development of research and therapeutic concepts for AD management.

MATERIAL AND METHODS

The present systematic review was performed using PubMed, Web of Science, and Scopus from April 2020 to May 2022 following the "Preferred Reporting Items for Systematic Reviews" (PRISMA) guidelines. The keywords, including "Conditioned medium OR Conditioned media OR Stem cell therapy" AND "Alzheimer's," was searched, and finally, 13 papers were extracted.

RESULTS

The obtained data revealed that MSC-CMs might positively affect neurodegenerative diseases prognosis, especially AD, through various mechanisms, including a decrease in neuro-inflammation, reduction of oxidative stress and Aβ formation, modulation of Microglia function and count, reduction of apoptosis, induction of synaptogenesis and neurogenesis. Also, the results showed that MSC-CM administration could significantly improve cognitive and memory function, increase the expression of neurotrophic factors, decrease the production of pro-inflammatory cytokines, improve mitochondrial function, reduce cytotoxicity, and increase neurotransmitter levels.

CONCLUSION

While inhibiting the induction of neuroinflammation could be considered the first therapeutic effect of CMs, the prevention of apoptosis could be regarded as the most crucial effect of CMs on AD improvement.

Gene Therapy for Inborn Errors of Immunity

In the early 1990s, gene therapy (GT) entered the clinical arena as an alternative to hematopoietic stem cell transplantation for forms of inborn errors of immunity (IEIs) that are not medically manageable because of their severity. In principle, the use of gene-corrected autologous hematopoietic stem cells presents several advantages over hematopoietic stem cell transplantation, including making donor searches unnecessary and avoiding the risks for graft-versus-host disease. In the past 30 years or more of clinical experience, the field has witnessed multiple examples of successful applications of GT to a number of IEIs, as well as some serious drawbacks, which have highlighted the potential genotoxicity of integrating viral vectors and stimulated important progress in the development of safer gene transfer tools. The advent of gene editing technologies promises to expand the spectrum of IEIs amenable to GT to conditions caused by mutated genes that require the precise regulation of expression or by dominant-negative variants. Here, we review the main concepts of GT as it applies to IEIs and the clinical results obtained to date. We also describe the challenges faced by this branch of medicine, which operates in the unprofitable sector of human rare diseases.

Updated Management Guidelines for Adenosine Deaminase Deficiency

Inherited defects in the adenosine deaminase (ADA) gene typically cause severe combined immunodeficiency. In addition to infections, ADA-deficient patients can present with neurodevelopmental, behavioral, hearing, skeletal, lung, heart, skin, kidney, urogenital, and liver abnormalities. Some patients also suffer from autoimmunity and malignancies. In recent years, there have been remarkable advances in the management of ADA deficiency. Most ADA-deficient patients can be identified by newborn screening for severe combined immunodeficiency, which facilitates early diagnosis and treatment of asymptomatic infants. Most patients benefit from enzyme replacement therapy (ERT). Allogeneic hematopoietic cell transplantation from an HLA-matched sibling donor or HLA-matched family member donor with no conditioning is currently the preferable treatment. When matched sibling donor or matched family member donor is not available, autologous ADA gene therapy with nonmyeloablative conditioning and ERT withdrawal, which is reported in recent studies to result in 100% overall survival and 90% to 95% engraftment, should be pursued. If gene therapy is not immediately available, ERT can be continued for a few years, although its excessive cost might be prohibitive. The recent improved outcome of hematopoietic cell transplantation using HLA-mismatched family-related donors or HLA-matched unrelated donors, after reduced-intensity conditioning, suggests that such procedures might also be considered rather than continuing ERT for prolonged periods. Long-term follow-up will further assist in determining the optimal treatment approach for ADA-deficient patients.

National experience with adenosine deaminase deficiency related SCID in Polish children

Introduction

Deficiency of adenosine deaminase (ADA) manifests as severe combined immunodeficiency (SCID), caused by accumulation of toxic purine degradation by-products. Untreated patients develop immune and non-immune symptoms with fatal clinical course. According to ESID and EBMT recommendations enzyme replacement therapy (ERT) should be implemented as soon as possible to stabilize the patient's general condition, normalize transaminases, treat pulmonary proteinosis, bone dysplasia, and protect from neurological damage. Hematopoietic stem cell transplantation (HSCT) from a matched related donor (MRD) is a treatment of choice. In absence of such donor, gene therapy (GT) should be considered. HSCT from a matched unrelated donor (MUD) and haploidentical hematopoietic stem cell transplantation (hHSCT) are associated with worse prognosis.

Material and methods

We retrospectively evaluated the clinical course and results of biochemical, immunological and genetic tests of 7 patients diagnosed in Poland with ADA deficiency since 2010 to 2022.

Results

All patients demonstrated lymphopenia affecting of T, B and NK cells. Diagnosis was made on the basis of ADA activity in red blood cells and/or genetic testing. Patients manifested with various non-immunological symptoms including: lung proteinosis, skeletal dysplasia, liver dysfunction, atypical hemolytic-uremic syndrome, and psychomotor development disorders. Five patients underwent successful HSCT: 3 patients from matched unrelated donor, 2 from matched sibling donor, and 1 haploidentical from a parental donor. In 4 patients HSCT was preceded by enzyme therapy (lasting from 2 to 5 months). One patient with multiple organ failure died shortly after admission, before the diagnosis was confirmed. None of the patients had undergone gene therapy.

Conclusions

It is important to diagnose ADA SCID as early as possible, before irreversible multi-organ failure occurs. In Poland HSCT are performed according to international immunological societies recommendations, while ERT and GT are less accessible. Implementation of Newborn Screening (NBS) for SCID in Poland could enable recognition of SCID, including ADA-SCID.

Congenital Athymia: Unmet Needs and Practical Guidance

Inborn errors of thymic stromal cell development and function which are associated with congenital athymia result in life-threatening immunodeficiency with susceptibility to infections and autoimmunity. Athymic patients can be treated by thymus transplantation using cultured donor thymus tissue. Outcomes in patients treated at Duke University Medical Center and Great Ormond Street Hospital (GOSH) over the past three decades have shown that sufficient T-cell immunity can be recovered to clear and prevent infections, but post-treatment autoimmune manifestations are relatively common. Whilst thymus transplantation offers the chance of long-term survival, significant challenges remain to optimise the outcomes for the patients. In this review, we will discuss unmet needs and offer practical guidance based on the experience of the European Thymus Transplantation programme at GOSH. Newborn screening (NBS) for severe combined immunodeficiency (SCID) and routine use of next-generation sequencing (NGS) platforms have improved early recognition of congenital athymia and increasing numbers of patients are being referred for thymus transplantation. Nevertheless, there remain delays in diagnosis, in particular when the cause is genetically undefined, and treatment accessibility needs to be improved. The majority of athymic patients have syndromic features with acute and chronic complex health issues, requiring life-long multidisciplinary and multicentre collaboration to optimise their medical and social care. Comprehensive follow up after thymus transplantation including monitoring of immunological results, management of co-morbidities and patient and family quality-of-life experience, is vital to understanding long-term outcomes for this rare cohort of patients. Alongside translational research into improving strategies for thymus replacement therapy, patient-focused clinical research will facilitate the design of strategies to improve the overall care for athymic patients.

Outcomes following treatment for ADA-deficient severe combined immunodeficiency: a report from the PIDTC

Adenosine deaminase (ADA) deficiency causes ∼13% of cases of severe combined immune deficiency (SCID). Treatments include enzyme replacement therapy (ERT), hematopoietic cell transplant (HCT), and gene therapy (GT). We evaluated 131 patients with ADA-SCID diagnosed between 1982 and 2017 who were enrolled in the Primary Immune Deficiency Treatment Consortium SCID studies. Baseline clinical, immunologic, genetic characteristics, and treatment outcomes were analyzed. First definitive cellular therapy (FDCT) included 56 receiving HCT without preceding ERT (HCT); 31 HCT preceded by ERT (ERT-HCT); and 33 GT preceded by ERT (ERT-GT). Five-year event-free survival (EFS, alive, no need for further ERT or cellular therapy) was 49.5% (HCT), 73% (ERT-HCT), and 75.3% (ERT-GT; P < .01). Overall survival (OS) at 5 years after FDCT was 72.5% (HCT), 79.6% (ERT-HCT), and 100% (ERT-GT; P = .01). Five-year OS was superior for patients undergoing HCT at <3.5 months of age (91.6% vs 68% if ≥3.5 months, P = .02). Active infection at the time of HCT (regardless of ERT) decreased 5-year EFS (33.1% vs 68.2%, P < .01) and OS (64.7% vs 82.3%, P = .02). Five-year EFS (90.5%) and OS (100%) were best for matched sibling and matched family donors (MSD/MFD). For patients treated after the year 2000 and without active infection at the time of FDCT, no difference in 5-year EFS or OS was found between HCT using a variety of transplant approaches and ERT-GT. This suggests alternative donor HCT may be considered when MSD/MFD HCT and GT are not available, particularly when newborn screening identifies patients with ADA-SCID soon after birth and before the onset of infections. This trial was registered at www.clinicaltrials.gov as #NCT01186913 and #NCT01346150.

Hematopoietic Cell Transplantation for Adenosine Deaminase Severe Combined Immunodeficiency-Improved Outcomes in the Modern Era

Current treatment for adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID) includes enzyme replacement therapy (ERT), allogeneic hematopoietic stem cell transplant (HSCT), or ex vivo corrected autologous hematopoietic stem cell gene therapy. Historic data show HSCT survival is superior using unconditioned matched sibling and family compared to matched unrelated and haploidentical donors. Recent improvement in HSCT outcomes prompted us to retrospectively examine HSCT survival and long-term graft function in ADA-SCID transplanted at our center. Thirty-three ADA-deficient patients received HSCT between 1989 and 2020, with follow-up data to January 2021. Chemotherapy conditioning regimens were defined as myeloablative (MAC-busulfan/cyclophosphamide), reduced-toxicity myeloablative (RT-MAC-treosulfan-based, since 2007), or no conditioning. Serotherapy used included alemtuzumab (with or without other conditioning agents) or antithymocyte globulin (ATG). ERT was introduced routinely in 2010 until commencement of conditioning. Median age at HSCT was 3.2 (0.8-99.8) months. Twenty-one (63.6%) received stem cells from unrelated or haploidentical donors. Seventeen (51.5%) received chemotherapy conditioning and 16 (48.5%) received alemtuzumab. Median follow-up was 7.5 (0.8-25.0) years. Overall survival (OS) and event-free survival (EFS) at 8 years were 90.9% (95% CI: 79.7-100.0%) and 79% (55-91%), respectively. OS after 2007 (n = 21) was 100% vs 75% before 2007 (n = 12) (p = 0.02). Three (9.1%) died after HSCT: two from multiorgan failure and one from unexplained encephalopathy. There were no deaths after 2007, among those who received ERT and treosulfan-based conditioning pre-HSCT. Ten (30.3%) developed acute GvDH (3 grade II, 2 grade III); no chronic GvHD was observed. In the modern era, conditioned HSCT with MUD has a favorable outcome for ADA-deficient patients.