Cerebral lymphoma in an adenosine deaminase-deficient patient with severe combined immunodeficiency receiving polyethylene glycol-conjugated adenosine deaminase

Successful management of delayed-onset adenosine deaminase deficiency with novel mutation

A 4-year-old boy presented with acute-onset autoimmune cytopenia with severe, persistent lymphopenia, autoimmune thyroiditis, elevated IgE and glucose 6-phosphate dehydrogenase enzyme deficiency. In immunologic evaluation, lower T, B and natural killer cells and higher levels of adenosine deaminase (ADA) metabolites were observed. The compound heterozygous novel ADA gene mutations causing ADA deficiency were detected. Successful immunologic and metabolic cure was achieved with enzyme replacement therapy, followed by reduced intensity conditioning hematopoietic stem cell transplantation from a matched unrelated donor. An interesting aspect of this patient is the detection of novel compound heterozygous mutations without consanguinity and a secondary outcome is the recovery of glucose 6-phosphate dehydrogenase deficiency after hematopoietic stem cell transplantation.

Malignancy-associated immune responses: Lessons from human inborn errors of immunity

It is widely understood that cancer is a significant cause of morbidity and mortality worldwide. Despite numerous available treatments, prognosis for many remains poor, thus, the development of novel therapies remains essential. Given the incredible success of many immunotherapies in this field, the important contribution of the immune system to the control, and elimination, of malignancy is clear. While many immunotherapies target higher-order pathways, for example, through promoting T-cell activation via immune checkpoint blockade, the potential to target specific immunological pathways is largely not well researched. Precisely understanding how immunity can be tailored to respond to specific challenges is an exciting idea with great potential, and may trigger the development of new therapies for cancer. Inborn Errors of Immunity (IEI) are a group of rare congenital disorders caused by gene mutations that result in immune dysregulation. This heterogeneous group, spanning widespread, multisystem immunopathology to specific immune cell defects, primarily manifest in immunodeficiency symptoms. Thus, these patients are particularly susceptible to life-threatening infection, autoimmunity and malignancy, making IEI an especially complex group of diseases. While precise mechanisms of IEI-induced malignancy have not yet been fully elucidated, analysis of these conditions can highlight the importance of particular genes, and downstream immune responses, in carcinogenesis and may help inform mechanisms which can be utilised in novel immunotherapies. In this review, we examine the links between IEIs and cancer, establishing potential connections between immune dysfunction and malignancy and suggesting roles for specific immunological mechanisms involved in preventing carcinogenesis, thus, guiding essential future research focused on cancer immunotherapy and providing valuable insight into the workings of the immune system in both health and disease.

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.

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.

Comparison of elapegademase and pegademase in ADA-deficient patients and mice

The absence of adenosine deaminase (ADA) causes severe combined immune deficiency (SCID), which has been treated with PEGylated bovine-extracted ADA (ADAGEN). ADAGEN was recently replaced by a PEGylated recombinant bovine ADA, expressed in Escherichia coli (elapegademase, ELA-ADA). Limited information on ELA-ADA is available.  ADA enzymatic activity of ELA-ADA and ADAGEN was assessed in vitro at diverse dilutions. ADA activity and immune reconstitution in an ADA-SCID patient treated with ELA-ADA were compared with age-matched patients previously treated with ADAGEN. ADA activity and thymus reconstitution were evaluated in ADA-deficient mice following ELA-ADA or ADAGEN administered from 7 days postpartum. In vitro, ADA activity of ELA-ADA and ADAGEN were similar at all dilutions. In an ADA-SCID patient, ELA-ADA treatment led to a marked increase in trough plasma ADA activity, which was 20% higher than in a patient previously treated with ADAGEN. A marked increase in T cell numbers and generation of naive T cells was evident following 3 months of ELA-ADA treatment, while T cell numbers increased following 4 months in 3 patients previously treated with ADAGEN. T cell proliferations stimulation normalized and thymus shadow became evident following ELA-ADA treatment. ADA activity was significantly increased in the blood of ADA-deficient mice following ELA-ADA compared to ADAGEN, while both treatments improved the mice weights, the weight, number of cells in their thymus and thymocyte subpopulations. ELA-ADA has similar in- vitro and possibly better in-vivo activity than ADAGEN. Future studies will determine whether ELA-ADA results in improved long-term immune reconstitution.

Consensus approach for the management of severe combined immune deficiency caused by adenosine deaminase deficiency

Inherited defects in adenosine deaminase (ADA) cause a subtype of severe combined immunodeficiency (SCID) known as severe combined immune deficiency caused by adenosine deaminase defects (ADA-SCID). Most affected infants can receive a diagnosis while still asymptomatic by using an SCID newborn screening test, allowing early initiation of therapy. We review the evidence currently available and propose a consensus management strategy. In addition to treatment of the immune deficiency seen in patients with ADA-SCID, patients should be followed for specific noninfectious respiratory, neurological, and biochemical complications associated with ADA deficiency. All patients should initially receive enzyme replacement therapy (ERT), followed by definitive treatment with either of 2 equal first-line options. If an HLA-matched sibling donor or HLA-matched family donor is available, allogeneic hematopoietic stem cell transplantation (HSCT) should be pursued. The excellent safety and efficacy observed in more than 100 patients with ADA-SCID who received gammaretrovirus- or lentivirus-mediated autologous hematopoietic stem cell gene therapy (HSC-GT) since 2000 now positions HSC-GT as an equal alternative. If HLA-matched sibling donor/HLA-matched family donor HSCT or HSC-GT are not available or have failed, ERT can be continued or reinstituted, and HSCT with alternative donors should be considered. The outcomes of novel HSCT, ERT, and HSC-GT strategies should be evaluated prospectively in "real-life" conditions to further inform these management guidelines.

First Occurrence of Plasmablastic Lymphoma in Adenosine Deaminase-Deficient Severe Combined Immunodeficiency Disease Patient and Review of the Literature

Adenosine deaminase-deficient severe combined immunodeficiency disease (ADA-SCID) is a primary immune deficiency characterized by mutations in the ADA gene resulting in accumulation of toxic compounds affecting multiple districts. Hematopoietic stem cell transplantation (HSCT) from a matched donor and hematopoietic stem cell gene therapy are the preferred options for definitive treatment. Enzyme replacement therapy (ERT) is used to manage the disease in the short term, while a decreased efficacy is reported in the medium-long term. To date, eight cases of lymphomas have been described in ADA-SCID patients. Here we report the first case of plasmablastic lymphoma occurring in a young adult with ADA-SCID on long-term ERT, which turned out to be Epstein–Barr virus associated. The patient previously received infusions of genetically modified T cells. A cumulative analysis of the eight published cases of lymphoma from 1992 to date, and the case here described, reveals a high mortality (89%). The most common form is diffuse large B-cell lymphoma, which predominantly occurs in extra nodal sites. Seven cases occurred in patients on ERT and two after haploidentical HSCT. The significant incidence of immunodeficiency-associated lymphoproliferative disorders and poor survival of patients developing this complication highlight the priority in finding a prompt curative treatment for ADA-SCID.

Long-Term Outcome of Adenosine Deaminase-Deficient Patients-a Single-Center Experience

PURPOSE

Inherited defects in the adenosine deaminase (ADA) enzyme can cause severe combined immune deficiency (SCID) and systemic abnormalities. Management options for ADA-deficient patients include enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT), and gene therapy (GT). Here, we describe the long-term benefits of these treatments.

METHODS

Survival, infections, systemic sequelae, and laboratory assessments were recorded for all ADA-deficient SCID patients, managed at a single center since 1985, who survived 5 or more years following treatment.

RESULTS

Of 20 ADA-deficient patients, the 8 (40%) who survived 5 or more years (range 6-29.5 years, median 14 years) were included in the study. Among the long-term survivors, two patients were treated exclusively with ERT, five underwent HSCT (three from HLA-matched sibling donors, two from HLA-mismatched related donors), and one received GT. The long-term survivors often suffered from recurrent respiratory infections; however, opportunistic infections occurred in only one patient. Systemic sequelae included lung disease such as bronchiectasis and asthma (four patients), neurologic abnormalities (six patients), metabolic disturbances (two patients), allergy and autoimmunity (six patients), and neoplasms (three patients). Normal CD4⁺ T cell numbers and function, as well as antibody production, were usually observed after HSCT and GT, but not after ERT. Late deaths occurred in two patients at 15 and 25 years after HSCT, respectively, and were attributed to respiratory failure.

CONCLUSIONS

ADA-deficient patients commonly suffer from long-term complications, emphasizing the need for improved management and for multi-disciplinary follow-up.

A 24-Year Enzyme Replacement Therapy in an Adenosine-deaminase-Deficient Patient

Severe combined immunodeficiency (SCID) is a fatal childhood disease unless immune reconstitution is performed early in life, with either hematopoietic stem cell transplantation or gene therapy. One of its subtypes is caused by adenosine deaminase (ADA) enzyme deficiency, which leads to the accumulation of toxic metabolites that impair lymphocyte development and function. With the development of polyethylene glycol-conjugated adenosine deaminase (PEG-ADA) enzyme replacement therapy, many ADA-deficient children with SCID who could not receive a hematopoietic stem cell transplantation or gene therapy survived and had longer and healthier lives. We report a 24-year course of treatment in a patient who was diagnosed with ADA deficiency at 4 months of age. The patient was treated with PEG-ADA, which was the only therapy available for him. The patient's plasma ADA level was regularly monitored and the PEG-ADA dose adjusted accordingly. This treatment has resulted in near-normalization of lymphocyte counts, and his clinical course has been associated with only minor to moderate infections. Thus far, he has had no manifestations of autoimmune or lymphoproliferative disorders. This patient is among the longest to be maintained on PEG-ADA enzyme replacement therapy.

Somatic mosaicism caused by monoallelic reversion of a mutation in T cells of a patient with ADA-SCID and the effects of enzyme replacement therapy on the revertant phenotype

Patients with adenosine deaminase (ADA) deficiency exhibit spontaneous and partial clinical remission associated with somatic reversion of inherited mutations. We report a child with severe combined immunodeficiency (T-B- SCID) due to ADA deficiency diagnosed at the age of 1 month, whose lymphocyte counts including CD4+ and CD8+ T and NK cells began to improve after several months with normalization of ADA activity in Peripheral blood lymphocytes (PBL), as a result of somatic mosaicism caused by monoallelic reversion of the causative mutation in the ADA gene. He was not eligible for haematopoietic stem cell transplantation (HSCT) or gene therapy (GT); therefore he was placed on enzyme replacement therapy (ERT) with bovine PEG-ADA. The follow-up of metabolic and immunologic responses to ERT included gradual improvement in ADA activity in erythrocytes and transient expansion of most lymphocyte subsets, followed by gradual stabilization of CD4+ and CD8+ T (with naïve phenotype) and NK cells, and sustained expansion of TCRγδ+ T cells. This was accompanied by the disappearance of the revertant T cells as shown by DNA sequencing from PBL. Although the patient's clinical condition improved marginally, he later developed a germinal cell tumour and eventually died at the age of 67 months from sepsis. This case adds to our current knowledge of spontaneous reversion of mutations in ADA deficiency and shows that the effects of the ERT may vary among these patients, suggesting that it could depend on the cell and type in which the somatic mosaicism is established upon reversion.

Primary immunodeficiency diseases associated with neurologic manifestations

Primary immunodeficiency diseases (PID) are a heterogeneous group of inherited disorders of the immune system, predisposing individuals to recurrent infections, allergy, autoimmunity, and malignancies. A considerable number of these conditions have been found to be also associated with neurologic signs and symptoms. These manifestations are considered core features of some immunodeficiency syndromes, such as ataxia-telangiectasia and purine nucleoside phosphorylase deficiency, or occur less prominently in some others. Diverse pathological mechanisms including defective responses to DNA damage, metabolic errors, and autoimmune phenomena have been associated with neurologic abnormalities; however, several issues remain to be elucidated. Greater awareness of these associated features and gaining a better understanding of the contributing mechanisms will lead to prompt diagnosis and treatment and possibly development of novel preventive and therapeutic strategies. In this review, we aim to provide a brief description of the clinical and genetic characteristics of PID associated with neurologic complications.

How I treat ADA deficiency

Adenosine deaminase deficiency is a disorder of purine metabolism leading to severe combined immunodeficiency (ADA-SCID). Without treatment, the condition is fatal and requires early intervention. Haematopoietic stem cell transplantation is the major treatment for ADA-SCID, although survival following different donor sources varies considerably. Unlike other SCID forms, 2 other options are available for ADA-SCID: enzyme replacement therapy (ERT) with pegylated bovine ADA, and autologous haematopoietic stem cell gene therapy (GT). Due to the rarity of the condition, the lack of large scale outcome studies, and availability of different treatments, guidance on treatment strategies is limited. We have reviewed the currently available evidence and together with our experience of managing this condition propose a consensus management strategy. Matched sibling donor transplants represent a successful treatment option with high survival rates and excellent immune recovery. Mismatched parental donor transplants have a poor survival outcome and should be avoided unless other treatments are unavailable. ERT and GT both show excellent survival, and therefore the choice between ERT, MUD transplant, or GT is difficult and dependent on several factors, including accessibility to the different modalities, response of patients to long-term ERT, and the attitudes of physicians and parents to the short- and potential long-term risks associated with different treatments.

Towards a rAAV-based gene therapy for ADA-SCID: from ADA deficiency to current and future treatment strategies

Adenosine deaminase deficiency fosters a rare, devastating pediatric immune deficiency with concomitant opportunistic infections, metabolic anomalies and multiple organ system pathology. The standard of care for adenosine deaminase deficient severe combined immune deficiency (ADA-SCID) includes enzyme replacement therapy or bone marrow transplantation. Gene therapies for ADA-SCID over nearly two decades have exclusively involved retroviral vectors targeted to lymphocytes and hematopoetic progenitors. These groundbreaking gene therapies represent a revolution in clinical medicine, but come with several challenges, including the risk of insertional mutagenesis. An alternative gene therapy for ADA-SCID may utilize recombinant adeno-associated virus vectors in vivo, with numerous target tissues, to foster ectopic expression and secretion of adenosine deaminase. This review endeavors to describe ADA-SCID, the traditional treatments, previous retroviral gene therapies, and primarily, alternative recombinant adeno-associated virus-based strategies to remedy this potentially fatal genetic disease.

Burkitt's lymphoma in a patient with adenosine deaminase deficiency-severe combined immunodeficiency treated with polyethylene glycol-adenosine deaminase

We describe a patient with severe combined immunodeficiency because of aberrations in adenosine deaminase (ADA) who despite adequate replacement with polyethylene glycol-linked ADA (PEG-ADA) for 13 years developed Burkitt's lymphoma. Although treatment corrected the metabolic abnormalities caused by ADA deficiency, it failed to fully restore cellular immunity.

Management options for adenosine deaminase deficiency; proceedings of the EBMT satellite workshop (Hamburg, March 2006)

Adenosine deaminase (ADA) deficiency is a disorder of purine salvage that has its most devastating consequences in the immune system leading to severe combined immunodeficiency (SCID). Management options for ADA SCID include hematopoietic stem cell transplantation, enzyme replacement therapy and gene therapy. Formal data on the outcome following each of the three treatment modalities are limited, and this symposium was held in order to gather together the experience from major centers in Europe and the US. Transplantation for ADA-SCID is highly successful with survival rates of approximately 90% if a matched sibling or matched related donor is available but survival following matched unrelated donor or haploidentical procedures is 63% and 50% respectively with a significant rejection/non-engraftment rate in unconditioned procedures. Successfully transplanted patients demonstrated good immunological recovery with normal cellular and humoral function in the majority of cases. PEG-ADA has been used in over 150 patients worldwide either as an alternative to mismatched transplant or as a stabilizing measure prior to transplant. Overall, approximately two thirds of patients treated with PEG-ADA have survived with the majority of patients showing good clinical improvement. The level of immune recovery long term was less than that seen after transplant and approximately 50% of patients continued to receive immunoglobulin replacement. Gene therapy has been used as an experimental procedure in two centers in Europe. Early results from 9 patients suggest that the treatment is safe and that the majority have shown recovery of cellular immune function. Long-term follow-up of treated patients highlights a significant incidence of non-immunological problems with cognitive, neurological and audiological abnormalities most prominent.

Ex vivo gene therapy with lentiviral vectors rescues adenosine deaminase (ADA)–deficient mice and corrects their immune and metabolic defects

Adenosine deaminase (ADA) deficiency is caused by a purine metabolic dysfunction, leading to severe combined immunodeficiency (SCID) and multiple organ damage. To investigate the efficacy of ex vivo gene therapy with self-inactivating lentiviral vectors (LVs) in correcting this complex phenotype, we used an ADA–/– mouse model characterized by early postnatal lethality. LV-mediated ADA gene transfer into bone marrow cells combined with low-dose irradiation rescued mice from lethality and restored their growth, as did transplantation of wild-type bone marrow. Mixed chimerism with multilineage engraftment of transduced cells was detected in the long term in animals that underwent transplantation. ADA activity was normalized in lymphocytes and partially corrected in red blood cells (RBCs), resulting in full metabolic detoxification and prevention of severe pulmonary insufficiency. Moreover, gene therapy restored normal lymphoid differentiation and immune functions, including antigen-specific antibody production. Similar degrees of detoxification and immune reconstitution were obtained in mice treated early after birth or after 1 month of enzyme-replacement therapy, mimicking 2 potential applications for ADA-SCID. Overall, this study demonstrates the efficacy of LV gene transfer in correcting both the immunological and metabolic phenotypes of ADA-SCID and supports the future clinical use of this approach.

Successful reconstitution of immunity in ADA-SCID by stem cell gene therapy following cessation of PEG-ADA and use of mild preconditioning

Gene therapy is a promising treatment option for monogenic diseases, but success has been seen in only a handful of studies thus far. We now document successful reconstitution of immune function in a child with the adenosine deaminase (ADA)-deficient form of severe combined immunodeficiency (SCID) following hematopoietic stem cell (HSC) gene therapy. An ADA-SCID child who showed a poor response to PEG-ADA enzyme replacement was enrolled into the clinical study. Following cessation of enzyme replacement therapy, autologous CD34(+) HSCs were transduced with an ADA-expressing gammaretroviral vector. Gene-modified cells were reinfused following one dose of preconditioning chemotherapy. Two years after the procedure, immunological and biochemical correction has been maintained with progressive increase in lymphocyte numbers, reinitiation of thymopoiesis, and systemic detoxification of ADA metabolites. Sustained vector marking with detection of polyclonal vector integration sites in multiple cell lineages and detection of ADA activity in red blood cells suggests transduction of early hematopoietic progenitors. No serious side effects were seen either as a result of the conditioning procedure or due to retroviral insertion. Gene therapy is an effective treatment option for the treatment of ADA-SCID.