Reversal of early neurologic and neuroradiologic manifestations of X-linked adrenoleukodystrophy by bone marrow transplantation

Haploidentical hematopoietic stem cell transplantation with busulfan, cyclophosphamide, and fludarabine conditioning for X-linked adrenal cerebral leukodystrophy

OBJECTIVE

We investigated the safety and efficacy of haploidentical stem cell transplantation (SCT) in pediatric patients with X-linked adrenoleukodystrophy (ALD).

METHODS

A retrospective analysis of transplantation data from 29 cases of ALD, treated between December 2014 and April 2022, was conducted. Neurologic function scores (NFS) were assessed. The conditioning regimen was busulfan 9.6 mg/kg, cyclophosphamide 200 mg/kg, and fludarabine 90 mg/m2 (BFC). Graft-versus-host disease prophylaxis consisted of anti-human thymocyte globulin, cyclosporine A, mycophenolate mofetil, and short course of methotrexate.

RESULTS

Among the 29 cases, 14 cases (NFS = 0) were asymptomatic, and 15 (NFS ≥ 1) were symptomatic. The median age at SCT was 8 years (range: 4-16 years); the median follow-up time was 1058 days (range: 398-3092 days); 28 cases were father donors and 1 case was a grandfather donor. Hematopoietic reconstitution was successful in all patients, and all of them achieved complete donor chimerism at the time of engraftment. The leading cause of death was still primary disease progression (n = 4). Survival free of major functional disabilities was 100% in asymptomatic patients versus 66.67% in the symptomatic group (p = .018).

CONCLUSION

BFC regimen used in haploidentical SCT was administered safely without major transplant-related complications even in symptomatic patients, and neurological symptoms were stabilized after SCT.

The pathology of X-linked adrenoleukodystrophy: tissue specific changes as a clue to pathophysiology

Although the pathology of X-linked adrenoleukodystrophy (ALD) is well described, it represents the end-stage of neurodegeneration. It is still unclear what cell types are initially involved and what their role is in the disease process. Revisiting the seminal post-mortem studies from the 1970s can generate new hypotheses on pathophysiology. This review describes (histo)pathological changes of the brain and spinal cord in ALD. It aims at integrating older works with current insights and at providing an overarching theory on the pathophysiology of ALD. The data point to an important role for axons and glia in the pathology of both the myelopathy and leukodystrophy of ALD. In-depth pathological analyses with new techniques could help further unravel the sequence of events behind the pathology of ALD.

Gene and Cellular Therapies for Leukodystrophies

Leukodystrophies are a heterogenous group of inherited, degenerative encephalopathies, that if left untreated, are often lethal at an early age. Although some of the leukodystrophies can be treated with allogeneic hematopoietic stem cell transplantation, not all patients have suitable donors, and new treatment strategies, such as gene therapy, are rapidly being developed. Recent developments in the field of gene therapy for severe combined immune deficiencies, Leber's amaurosis, epidermolysis bullosa, Duchenne's muscular dystrophy and spinal muscular atrophy, have paved the way for the treatment of leukodystrophies, revealing some of the pitfalls, but overall showing promising results. Gene therapy offers the possibility for overexpression of secretable enzymes that can be released and through uptake, allow cross-correction of affected cells. Here, we discuss some of the leukodystrophies that have demonstrated strong potential for gene therapy interventions, such as X-linked adrenoleukodystrophy (X-ALD), and metachromatic leukodystrophy (MLD), which have reached clinical application. We further discuss the advantages and disadvantages of ex vivo lentiviral hematopoietic stem cell gene therapy, an approach for targeting microglia-like cells or rendering cross-correction. In addition, we summarize ongoing developments in the field of in vivo administration of recombinant adeno-associated viral (rAAV) vectors, which can be used for direct targeting of affected cells, and other recently developed molecular technologies that may be applicable to treating leukodystrophies in the future.

Neurofilament light chain levels in cerebrospinal fluid as a sensitive biomarker for cerebral adrenoleukodystrophy

OBJECTIVE

Adrenoleukodystrophy (ALD) has a poor prognosis when it progresses to the cerebral form (CALD). The aim of this study is to investigate whether cerebrospinal fluid (CSF) neurofilament light chain (cNfL) is a sensitive biomarker for detecting CALD and assessing response to hematopoietic stem cell transplantation (HSCT).

METHODS

We conducted a cross-sectional study of 41 male ALD patients. The cNfL levels in patients with the cerebral form of ALD (CALD) or the cerebello-brainstem form of ALD were compared with those in patients with adrenomyeloneuropathy (AMN). The correlation between cNfL levels and MRI-based Loes severity scores was investigated. A longitudinal analysis was performed on patients who underwent multiple CSF examinations.

RESULTS

The cNfL levels in 22 patients with CALD were significantly higher than those in 14 patients with AMN (median, 5545 vs. 1490 pg/mL; p < 0.001). The cutoff cNfL level of 1930 pg/mL showed good sensitivity (95.5%) and specificity (85.7%) for distinguishing CALD from AMN. The cNfL levels were positively correlated with Loes scores (p < 0.001). The cNfL levels in three AMN patients who later converted to CALD increased above the cutoff level during the conversion period, while the cNfL levels in four patients who remained in AMN were consistently below the cutoff. In 10 ALD patients who underwent HSCT, their cNfL levels decreased 3-24 months after HSCT. Two patients whose cNfL increased after HSCT showed deterioration in cognitive functions.

INTERPRETATION

The cNfL level is useful for evaluating the disease activities of ALD and the response to HSCT.

Treatment of neurometabolic epilepsies: Overview and recent advances

The rarity and heterogeneity of neurometabolic diseases make it challenging to reach evidence-based principles for their specific treatments. Indeed, current treatments for many of these diseases remain symptomatic and supportive. However, an ongoing scientific and medical revolution has led to dramatic breakthroughs in molecular sciences and genetics, revealing precise pathophysiologic mechanisms. Accordingly, this has led to significant progress in the development of novel therapeutic approaches aimed at treating epilepsy resulting from these conditions, as well as their other manifestations. We overview recent notable treatment advancements, from vitamins, trace minerals, and diets to unique medications targeting the elemental pathophysiology at a molecular or cellular level, including enzyme replacement therapy, enzyme enhancing therapy, antisense oligonucleotide therapy, stem cell transplantation, and gene therapy.

Neurocognitive and mental health impact of adrenoleukodystrophy across the lifespan: Insights for the era of newborn screening

X-linked adrenoleukodystrophy (ALD) is a rare inherited neurological disorder that poses considerable challenges for clinical management throughout the lifespan. Although males are generally more severely affected than females, the time course and presentation of clinical symptoms are otherwise difficult to predict. Opportunities to improve outcomes for individuals with ALD are rapidly expanding due to the introduction of newborn screening programs for this condition and an evolving treatment landscape. The aim of this comprehensive review is to synthesize current knowledge regarding the neurocognitive and mental health effects of ALD. This review provides investigators and clinicians with context to improve case conceptualization, inform prognostic counseling, and optimize neuropsychological and mental health care for patients and their families. Results highlight key predictive factors and brain-behavior relationships associated with the diverse manifestations of ALD. The review also discusses considerations for endpoints within clinical trials and identifies gaps to address in future research.

Targeted Brain Delivery of Dendrimer-4-Phenylbutyrate Ameliorates Neurological Deficits in a Long-Term ABCD1-Deficient Mouse Model of X-Linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is a genetic disorder that presents neurologically as either a rapid and fatal cerebral demyelinating disease in childhood (childhood cerebral adrenoleukodystrophy; ccALD) or slow degeneration of the spinal cord in adulthood (adrenomyeloneuropathy; AMN). All forms of ALD result from mutations in the ATP Binding Cassette Subfamily D Member (ABCD) 1 gene, encoding a peroxisomal transporter responsible for the import of very long chain fatty acids (VLCFA) and results mechanistically in a complex array of dysfunction, including endoplasmic reticulum stress, oxidative stress, mitochondrial dysfunction, and inflammation. Few therapeutic options exist for these patients; however, an additional peroxisomal transport protein (ABCD2) has been successfully targeted previously for compensation of dysfunctional ABCD1. 4-Phenylbutyrate (4PBA), a potent activator of the ABCD1 homolog ABCD2, is FDA approved, but use for ALD has been stymied by a short half-life and thus a need for unfeasibly high doses. We conjugated 4PBA to hydroxyl polyamidoamine (PAMAM) dendrimers (D-4PBA) to a create a long-lasting and intracellularly targeted approach which crosses the blood-brain barrier to upregulate Abcd2 and its downstream pathways. Across two studies, Abcd1 knockout mice administered D-4PBA long term showed neurobehavioral improvement and increased Abcd2 expression. Furthermore, when the conjugate was administered early, significant reduction of VLCFA and improved survival of spinal cord neurons was observed. Taken together, these data show improved efficacy of D-4PBA compared to previous studies of free 4PBA alone, and promise for D-4PBA in the treatment of complex and chronic neurodegenerative diseases using a dendrimer delivery platform that has shown successes in recent clinical trials. While recovery in our studies was partial, combined therapies on the dendrimer platform may offer a safe and complete strategy for treatment of ALD.

Activating cannabinoid receptor 2 preserves axonal health through GSK-3β/NRF2 axis in adrenoleukodystrophy

Aberrant endocannabinoid signaling accompanies several neurodegenerative disorders, including multiple sclerosis. Here, we report altered endocannabinoid signaling in X-linked adrenoleukodystrophy (X-ALD), a rare neurometabolic demyelinating syndrome caused by malfunction of the peroxisomal ABCD1 transporter, resulting in the accumulation of very long-chain fatty acids (VLCFAs). We found abnormal levels of cannabinoid receptor 2 (CB2r) and related endocannabinoid enzymes in the brain and peripheral blood mononuclear cells (PBMCs) of X-ALD patients and in the spinal cord of a murine model of X-ALD. Preclinical treatment with a selective agonist of CB2r (JWH133) halted axonal degeneration and associated locomotor deficits, along with normalization of microgliosis. Moreover, the drug improved the main metabolic disturbances underlying this model, particularly in redox and lipid homeostatic pathways, including increased lipid droplets in motor neurons, through the modulation of the GSK-3β/NRF2 axis. JWH133 inhibited Reactive Oxygen Species elicited by excess VLCFAs in primary microglial cultures of Abcd1-null mice. Furthermore, we uncovered intertwined redox and CB2r signaling in the murine spinal cords and in patient PBMC samples obtained from a phase II clinical trial with antioxidants (NCT01495260). These findings highlight CB2r signaling as a potential therapeutic target for X-ALD and perhaps other neurodegenerative disorders that present with dysregulated redox and lipid homeostasis.

Gene Therapy for Pediatric Neurologic Disease

Pediatric lysosomal and peroxisomal storage disorders, leukodystrophies, and motor neuron diseases can have devastating neurologic manifestations. Despite efforts to exploit cross-correction to treat these monogenic disorders for several decades, definitive treatment has yet to be identified. This review explores recent attempts to transduce autologous hematopoietic stem cells with functional gene or provide therapeutic gene in vivo. Specifically, we discuss the rationale behind efforts to treat pediatric neurologic disorders with gene therapy, outline the specific disorders that have been targeted at this time, and review recent and current clinical investigations with attention to the future direction of therapy efforts.

Hematopoietic Stem Cell Transplantation for Neurological Disorders: A Focus on Inborn Errors of Metabolism

Hematopoietic stem cells have been investigated and applied for the treatment of certain neurological disorders for a long time. Currently, their therapeutic potential is harnessed in autologous and allogeneic hematopoietic stem cell transplantation (HSCT). Autologous HSCT is helpful in immune-mediated neurological diseases such as Multiple Sclerosis. However, clinical benefits derive more from the immunosuppressive conditioning regimen than the interaction between stem cells and the nervous system. Mainly used for hematologic malignancies, allogeneic HSCT explores the therapeutic potential of donor-derived hematopoietic stem cells. In the neurological setting, it has proven to be most valuable in Inborn Errors of Metabolism, a large spectrum of multisystem disorders characterized by congenital deficiencies in enzymes involved in metabolic pathways. Inborn Errors of Metabolism such as X-linked Adrenoleukodystrophy present with brain accumulation of enzymatic substrates that result in progressive inflammatory demyelination. Allogeneic HSCT can halt ongoing inflammatory neural destruction by replacing hematopoietic-originated microglia with donor-derived myeloid precursors. Microglia, the only neural cells successfully transplanted thus far, are the most valuable source of central nervous system metabolic correction and play a significant role in the crosstalk between the brain and hematopoietic stem cells. After transplantation, engrafted donor-derived myeloid cells modulate the neural microenvironment by recapitulating microglial functions and enhancing repair mechanisms such as remyelination. In some disorders, additional benefits result from the donor hematopoietic stem cell secretome that cross-corrects neighboring neural cells via mannose-6-phosphatase paracrine pathways. The limitations of allogeneic HSCT in this setting relate to the slow turnover of microglia and complications such as graft-vs.-host disease. These restraints have accelerated the development of hematopoietic stem cell gene therapy, where autologous hematopoietic stem cells are collected, manipulated ex vivo to overexpress the missing enzyme, and infused back into the patient. With this cellular drug vehicle strategy, the brain is populated by improved cells and exposed to supraphysiological levels of the flawed protein, resulting in metabolic correction. This review focuses on the mechanisms of brain repair resulting from HSCT and gene therapy in Inborn Errors of Metabolism. A brief mention will also be made on immune-mediated nervous system diseases that are treated with this approach.

Haematopoietic stem cell gene therapy in inborn errors of metabolism

Over the last 30 years, allogeneic haematopoietic stem cell transplantation (allo-HSCT) has been adopted as a therapeutic strategy for many inborn errors of metabolism (IEM), due to the ability of donor-derived cells to provide life-long enzyme delivery to deficient tissues and organs. However, (a) the clinical benefit of allo-HSCT is limited to a small number of IEM, (b) patients are left with a substantial residual disease burden and (c) allo-HSCT is still associated with significant short- and long-term toxicities and transplant-related mortality. Haematopoietic stem/progenitor cell gene therapy (HSPC-GT) was established in the 1990s for the treatment of selected monogenic primary immunodeficiencies and over the past few years, its use has been extended to a number of IEM. HSPC-GT is particularly attractive in neurodegenerative IEM, as gene corrected haematopoietic progenitors can deliver supra-physiological enzyme levels to difficult-to-reach areas, such as the brain and the skeleton, with potential increased clinical benefit. Moreover, HSPC-GT is associated with reduced morbidity and mortality compared to allo-HSCT, although this needs to be balanced against the potential risk of insertional mutagenesis. The number of clinical trials in the IEM field is rapidly increasing and some HSPC-GT products recently received market approval. This review describes the development of ex vivo HSPC-GT in a number of IEM, with a focus on recent results from GT clinical trials and risks versus benefits considerations, when compared to established therapeutic strategies, such as allo-HSCT.

Newborn Screen for X-Linked Adrenoleukodystrophy Using Flow Injection Tandem Mass Spectrometry in Negative Ion Mode

X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder caused by pathogenic variants in the ATP-binding cassette subfamily D member 1 gene (ABCD1) that encodes the adrenoleukodystrophy protein (ALDP). Defects in ALDP result in elevated cerotic acid, and lead to C26:0-lysophosphatidylcholine (C26:0-LPC) accumulation, which is the primary biomarker used in newborn screening (NBS) for X-ALD. C26:0-LPC levels were measured in dried blood spot (DBS) NBS specimens using a flow injection analysis (FIA) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS/MS) performed in negative ion mode. The method was validated by assessing and confirming linearity, accuracy, and precision. We have also established C26:0-LPC cutoff values that identify newborns at risk for X-ALD. The mean concentration of C26:0-LPC in 5881 de-identified residual routine NBS specimens was 0.07 ± 0.02 µM (mean + 1 standard deviation (SD)). All tested true X-ALD positive and negative samples were correctly identified based on C26:0-LPC cutoff concentrations for borderline between 0.15 µM and 0.22 µM (mean + 4 SD) and presumptive screening positive at ≥0.23 µM (mean + 8 SD). The presented FIA method shortens analysis run-time to 1.7 min, while maintaining the previously established advantage of utilizing negative mode MS to eliminate isobaric interferences that could lead to screening false positives.

Rectal cancer diagnosed after resection of isolated brain metastasis

Background

Brain metastasis of colorectal cancer is infrequent, and isolated brain metastases are more infrequent. Thus, when neurological symptoms, such as paralysis or disturbance of consciousness appear, there is a high probability that the cancer has spread to other organs.

Case presentation

Here, we present a 64-year-old man with a progressive headache, decreased motivation, and aphasia who was diagnosed with a brain tumor in the left frontal region. He underwent a craniotomy, and the brain tumor was diagnosed as adenocarcinoma. We performed a colonoscopy and diagnosed rectal cancer without other distant metastases. After whole-brain radiotherapy (WBRT), low anterior resection for primary rectal tumor was performed using a robotic system. The patient was discharged in good condition and received postoperative adjuvant therapy for rectal cancer. He showed no signs of recurrence after 1 year of follow-up.

Conclusions

We described a rare case of rectal cancer that was diagnosed after resection of isolated brain metastasis. A good prognosis was achieved with surgery and WBRT.

Long-term disease prevention with a gene therapy targeting oligodendrocytes in a mouse model of adrenomyeloneuropathy

Adrenomyeloneuropathy (AMN) is a late-onset axonopathy of spinal cord tracts caused by mutations of the ABCD1 gene that encodes ALDP, a peroxisomal transporter of very long chain fatty acids (VLCFA). Disturbed metabolic interaction between oligodendrocytes (OL) and axons is suspected to play a major role in AMN axonopathy. To develop a vector targeting OL, the human ABCD1 gene driven by a short 0.3 kb part of the human myelin-associated glycoprotein (MAG) promoter was packaged into an adeno-associated viral serotype 9 (rAAV9). An intravenous injection of this vector at postnatal day 10 (P10) in Abcd1-/- mice, a model of AMN, allowed a near normal motor performance to persist for 24 months, while age-matched untreated mice developed major defects of balance and motricity. Three weeks post vector, 50-54% of spinal cord white matter OL were expressing ALDP at the cervical level, and only 6-7% after 24 months. In addition, 29-32% of cervical spinal cord astrocytes at 3 weeks and 16-19% at 24 months also expressed ALDP. C26:0-lysoPC, a sensitive VLCFA marker of AMN, was lower by 41% and 50%, respectively in the spinal cord and brain of vector-treated compared with untreated mice. In a non-human primate (NHP), the intrathecal injection of the rAAV9-MAG vector induced abundant ALDP expression at 3 weeks in spinal cord OL (43%, 29%, 26% at cervical, thoracic and lumbar levels) and cerebellum OL (35%). In addition, 33-41 % of spinal cord astrocytes expressed hALDP, and 27% of cerebellar astrocytes. To our knowledge, OL targeting had not been obtained before in primates with other vectors or promoters. The current results thus provide a robust proof-of-concept not only for the gene therapy of AMN but for other CNS diseases where the targeting of OL with the rAAV9-MAG vector may be of interest.

Stem cell transplantation for pediatric patients with adrenoleukodystrophy: A nationwide retrospective analysis in Japan

BACKGROUND

Adrenoleukodystrophy (ALD) is an X-linked recessive disorder and 30-40% of patients develop progressive cerebral neurodegeneration. For symptomatic ALD patients, allogeneic stem cell transplantation (SCT) is considered the standard treatment modality to stabilize or prevent the progression of neurological symptoms.

METHODS

We retrospectively analyzed the transplant outcomes of 99 pediatric patients with cerebral ALD in Japan. The conditioning regimens included Regimen A: fludarabine/melphalan/low-dose total body irradiation (TBI) with brain sparing (n = 39), Regimen B; busulfan/cyclophosphamide ± others (n = 23), Regimen C: melphalan/total lymphoid irradiation/thoracoabdominal irradiation ± anti-T lymphocyte globulin ± fludarabine (n = 27), and Regimen D: others (n = 10).

RESULTS

The 5-year overall survival (OS) and event-free survival (EFS) of all patients were 90.0% and 72.9%, respectively. The 5-year OS was 100.0% for Regimen A, 91.1% for Regimen B, 84.4% for Regimen C, and 67.5% for Regimen D (p = 0.028). The 5-year EFS was 78.3% for Regimen A, 78.0% for Regimen B, 70.4% for Regimen C, and 48.0% for Regimen D (p = 0.304). The OS marginally improved after 2007 compared with before 2006 (95.3% vs. 85.2%, p = 0.066), due to the improvement of cord blood transplantation (CBT) outcomes after 2007 compared with before 2006 (96.6% vs. 68.4%, p = 0.005). On magnetic resonance imaging of the brain, a reduced Loes score after SCT was only observed in one of the 15 bone marrow transplantation (BMT) patients, but in 5 of the 15 CBT patients (p = 0.173).

CONCLUSIONS

Our study revealed that a reduced conditioning regimen with fludarabine/melphalan/low-dose TBI provides better outcomes, and the results of CBT significantly improved after 2007.

Variables Affecting Outcomes After Allogeneic Hematopoietic Stem Cell Transplant for Cerebral Adrenoleukodystrophy

Cerebral adrenoleukodystrophy manifests as progressive inflammatory demyelination leading to neurological function loss and early death.

Early allo-HSCT stabilizes cerebral adrenoleukodystrophy progression; TRM remains high, even with improved regimens and supportive care.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in early cerebral adrenoleukodystrophy can stabilize neurologic function and improve survival but has associated risks including transplant-related mortality (TRM), graft failure, and graft-versus-host disease (GVHD). An observational study of 59 patients with median age at allo-HSCT of 8 years addressed impact of donor source, donor match, conditioning regimen, and cerebral disease stage on first allo-HSCT outcomes. Efficacy analyses included 53 patients stratified by disease category: advanced disease (AD; n = 16) with Loes score >9 or neurological function score (NFS) >1 and 2 early disease (ED) cohorts (ED1 [Loes ≤4 and NFS ≤1; n = 24] and ED2 [Loes >4-9 and NFS ≤1; n = 13]). Survival free of major functional disabilities and without second allo-HSCT at 4 years was significantly higher in the ED (66%) vs AD (41%) cohort (P = .015) and comparable between ED1 and ED2 cohorts (P = .991). The stabilization of neurologic function posttransplant was greater in the ED vs AD cohort, with a median change from baseline at 24 months after allo-HSCT in NFS and Loes score, respectively, of 0 and 0.5 in ED1 (n = 13), 0.5 and 0 in ED2 (n = 6), and 2.5 and 3.0 (n = 4) in AD cohort. TRM was lower in the ED (7%) compared with the AD (22%) cohort; however, the difference was not significant (P = .094). Transplant-related safety outcomes were also affected by transplant-related characteristics: graft failure incidence was significantly higher with unrelated umbilical cord grafts vs matched related donors (P = .039), and acute GVHD and graft failure incidences varied by conditioning regimen. This study was registered at www://clinicaltrials.gov as #NCT02204904.

Management of adrenoleukodystrophy: From pre-clinical studies to the development of new therapies

X-linked adrenoleukodystrophy (X-ALD) is an inherited neurodegenerative disorder associated with mutations of the ABCD1 gene that encodes a peroxisomal transmembrane protein. It results in accumulation of very long chain fatty acids in tissues and body fluid. Along with other factors such as epigenetic and environmental involvement, ABCD1 mutation-provoked disorders can present different phenotypes including cerebral adrenoleukodystrophy (cALD), adrenomyeloneuropathy (AMN), and peripheral neuropathy. cALD is the most severe form that causes death in young childhood. Bone marrow transplantation and hematopoietic stem cell gene therapy are only effective when performed at an early stage of onsets in cALD. Nonetheless, current research and development of novel therapies are hampered by a lack of in-depth understanding disease pathophysiology and a lack of reliable cALD models. The Abcd1 and Abcd1/Abcd2 knock-out mouse models as well as the deficiency of Abcd1 rabbit models created in our lab, do not develop cALD phenotypes observed in human beings. In this review, we summarize the clinical and biochemical features of X-ALD, the progress of pre-clinical and clinical studies. Challenges and perspectives for future X-ALD studies are also discussed.

Modulation of mitochondrial and inflammatory homeostasis through RIP140 is neuroprotective in an adrenoleukodystrophy mouse model

AIMS

Mitochondrial dysfunction and inflammation are at the core of axonal degeneration in several multifactorial neurodegenerative diseases, including multiple sclerosis, Alzheimer's disease, and Parkinson's disease. The transcriptional coregulator RIP140/NRIP1 (receptor-interacting protein 140) modulates these functions in liver and adipose tissue, but its role in the nervous system remains unexplored. Here, we investigated the impact of RIP140 in the Abcd1^- mouse model of X-linked adrenoleukodystrophy (X-ALD), a genetic model of chronic axonopathy involving the convergence of redox imbalance, bioenergetic failure, and chronic inflammation.

METHODS AND RESULTS

We provide evidence that RIP140 is modulated through a redox-dependent mechanism driven by very long-chain fatty acids (VLCFAs), the levels of which are increased in X-ALD. Genetic inactivation of RIP140 prevented mitochondrial depletion and dysfunction, bioenergetic failure, inflammatory dysregulation, axonal degeneration and associated locomotor disabilities in vivo in X-ALD mouse models.

CONCLUSIONS

Together, these findings show that aberrant overactivation of RIP140 promotes neurodegeneration in X-ALD, underscoring its potential as a therapeutic target for X-ALD and other neurodegenerative disorders that present with metabolic and inflammatory dyshomeostasis.

Peroxisomal ABC Transporters: An Update

ATP-binding cassette (ABC) transporters constitute one of the largest superfamilies of conserved proteins from bacteria to mammals. In humans, three members of this family are expressed in the peroxisomal membrane and belong to the subfamily D: ABCD1 (ALDP), ABCD2 (ALDRP), and ABCD3 (PMP70). These half-transporters must dimerize to form a functional transporter, but they are thought to exist primarily as tetramers. They possess overlapping but specific substrate specificity, allowing the transport of various lipids into the peroxisomal matrix. The defects of ABCD1 and ABCD3 are responsible for two genetic disorders called X-linked adrenoleukodystrophy and congenital bile acid synthesis defect 5, respectively. In addition to their role in peroxisome metabolism, it has recently been proposed that peroxisomal ABC transporters participate in cell signaling and cell control, particularly in cancer. This review presents an overview of the knowledge on the structure, function, and mechanisms involving these proteins and their link to pathologies. We summarize the different in vitro and in vivo models existing across the species to study peroxisomal ABC transporters and the consequences of their defects. Finally, an overview of the known and possible interactome involving these proteins, which reveal putative and unexpected new functions, is shown and discussed.

Long-Term Follow-Up of Hematopoietic Stem-Cell Gene Therapy for Cerebral Adrenoleukodystrophy

In 2009, cerebral adrenoleukodystrophy (c-ALD) became the first brain disease to be treated with lentiviral (LV)-based hematopoietic stem cell gene therapy with the ABCD1 gene in four boys (P1-P4) who had demyelinating lesions expected to be lethal in the short term and no bone marrow donor. We report the clinical and magnetic resonance imaging (MRI) follow-up over a mean of 8.8 years posttransplant. In parallel, vector genome copies, expression of transgenic ALD protein (ALDP), and viral integration sites were determined in peripheral blood cells. Prior to transplant, the four patients had a normal or near normal neurocognitive status but gadolinium-enhanced demyelination in various brain regions. Gadolinium diffusion disappeared during the first year posttransplant. P3 kept a near normal status until 8.3 years of follow-up, but P1, P2, and P4 showed major cognitive degradation around 9, 28, and 60 months posttransplant. Neurological status and demyelination stabilized until last evaluation in P2, but deteriorated in both P1 at 10 years and P4 at 3 years posttransplant. The proportion of myeloid and lymphoid cells expressing transgenic ALDP decreased by half within 5 years then stabilized around 5% to 10%. Integration site analysis revealed a durable polyclonal distribution of genetically corrected hematopoietic cells. No adverse effects were observed. The long-term arrest of demyelination at MRI and persistence of transduced hematopoietic progenitors support that LV gene therapy may be a safe and durable treatment of c-ALD. However, the neurological degradation observed in three out of four patients mitigates the benefit of this therapy, calling for an earlier intervention, more potent vectors, and additional therapeutic strategies.

Bone marrow transplantation into Abcd1-deficient mice: Distribution of donor derived-cells and biological characterization of the brain of the recipient mice

X-linked adrenoleukodystrophy (X-ALD) is a severe inherited metabolic disease with cerebral inflammatory demyelination and abnormal accumulation of very long chain fatty acid (VLCFA) in tissues, especially the brain. At present, bone marrow transplantation (BMT) at an early stage of the disease is the only effective treatment for halting disease progression, but the underlying mechanism of the treatment has remained unclear. Here, we transplanted GFP-expressing wild-type (WT) or Abcd1-deficient (KO) bone marrow cells into recipient KO mice, which enabled tracking of the donor GFP⁺ cells in the recipient mice. Both the WT and KO donor cells were equally distributed throughout the brain parenchyma, and displayed an Iba1-positive, GFAP- and Olig2-negative phenotype, indicating that most of the donor cells were engrafted as microglia-like cells. They constituted approximately 40% of the Iba1-positive cells. Unexpectedly, no decrease of VLCFA in the cerebrum was observed when WT bone marrow cells were transplanted into KO mice. Taken together, murine study suggests that bone marrow-derived microglia-like cells engrafted in the cerebrum of X-ALD patients suppress disease progression without evidently reducing the amount of VLCFA in the cerebrum.

The Changing Face of Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a rare X-linked disorder of peroxisomal oxidation due to mutations in ABCD1. It is a progressive condition with a variable clinical spectrum that includes primary adrenal insufficiency, myelopathy, and cerebral ALD. Adrenal insufficiency affects over 80% of ALD patients. Cerebral ALD affects one-third of boys under the age of 12 and progresses to total disability and death without treatment. Hematopoietic stem cell transplantation (HSCT) remains the only disease-modifying therapy if completed in the early stages of cerebral ALD, but it does not affect the course of adrenal insufficiency. It has significant associated morbidity and mortality. A recent gene therapy clinical trial for ALD reported short-term MRI and neurological outcomes comparable to historical patients treated with HSCT without the associated adverse side effects. In addition, over a dozen states have started newborn screening (NBS) for ALD, with the number of states expecting to double in 2020. Genetic testing of NBS-positive neonates has identified novel variants of unknown significance, providing further opportunity for genetic characterization but also uncertainty in the monitoring and therapy of subclinical and/or mild adrenal insufficiency or cerebral involvement. As more individuals with ALD are identified at birth, it remains uncertain if availability of matched donors, transplant (and, potentially, gene therapy) centers, and specialists may affect the timely treatment of these individuals. As these promising gene therapy trials and NBS transform the clinical management and outcomes of ALD, there will be an increasing need for the endocrine management of presymptomatic and subclinical adrenal insufficiency. (Endocrine Reviews 41: 1 - 17, 2020).

Volume of Gadolinium Enhancement and Successful Repair of the Blood-Brain Barrier in Cerebral Adrenoleukodystrophy

Up to 40% of boys with adrenoleukodystrophy develop a severe central nervous system demyelinating form (cALD) characterized by white matter changes and gadolinium enhancement on magnetic resonance imaging (MRI). Hematopoietic cell transplant (HCT) is the only proven means to attenuate cALD progression. The elimination of active neuroinflammation is indicated radiographically by the resolution of gadolinium (Gd) enhancement and correlates to speed of donor neutrophil recovery. We analyzed 66 boys with cALD undergoing HCT for biomarkers correlating with early (30 days post-HCT) Gd signal resolution. We found that log Gd volume (cm³) on pre-HCT MRI strongly positively correlated to day 30 Gd resolution (P = .0003) with smaller volume correlating to higher proportion resolved, as was the baseline gadolinium intensity score (P = .04), plasma chitotriosidase activity (P = .04), and faster absolute neutrophil count recovery (P = .03). In multivariate analysis, log Gd volume remained superior in determining which patients would have Gd signal resolution by 30 days post-HCT (P = .016). A final analysis indicated that early Gd resolution also correlated with less neurologic progression from baseline to 1 year following HCT (P = .006). MRI Gd volume may serve as a contributing biomarker to better delineate outcomes and an important metric in comparing therapies in the treatment of cALD.

Adrenoleukodystrophy Newborn Screening in the Netherlands (SCAN Study): The X-Factor

X-linked adrenoleukodystrophy (ALD) is a devastating metabolic disorder affecting the adrenal glands, brain and spinal cord. Males with ALD are at high risk for developing adrenal insufficiency or progressive cerebral white matter lesions (cerebral ALD) at an early age. If untreated, cerebral ALD is often fatal. Women with ALD are not at risk for adrenal insufficiency or cerebral ALD. Newborn screening for ALD in males enables prospective monitoring and timely therapeutic intervention, thereby preventing irreparable damage and saving lives. The Dutch Ministry of Health adopted the advice of the Dutch Health Council to add a boys-only screen for ALD to the newborn screening panel. The recommendation made by the Dutch Health Council to only screen boys, without gathering any unsolicited findings, posed a challenge. We were invited to set up a prospective pilot study that became known as the SCAN study (SCreening for ALD in the Netherlands). The objectives of the SCAN study are: (1) designing a boys-only screening algorithm that identifies males with ALD and without unsolicited findings; (2) integrating this algorithm into the structure of the Dutch newborn screening program without harming the current newborn screening; (3) assessing the practical and ethical implications of screening only boys for ALD; and (4) setting up a comprehensive follow-up that is both patient- and parent-friendly. We successfully developed and validated a screening algorithm that can be integrated into the Dutch newborn screening program. The core of this algorithm is the “X-counter.” The X-counter determines the number of X chromosomes without assessing the presence of a Y chromosome. The X-counter is integrated as second tier in our 4-tier screening algorithm. Furthermore, we ensured that our screening algorithm does not result in unsolicited findings. Finally, we developed a patient- and parent-friendly, multidisciplinary, centralized follow-up protocol. Our boys-only ALD screening algorithm offers a solution for countries that encounter similar ethical considerations, for ALD as well as for other X-linked diseases. For ALD, this alternative boys-only screening algorithm may result in a more rapid inclusion of ALD in newborn screening programs worldwide.

The peroxisomal fatty acid transporter ABCD1/PMP-4 is required in the C. elegans hypodermis for axonal maintenance: A worm model for adrenoleukodystrophy

Adrenoleukodystrophy is a neurometabolic disorder caused by a defective peroxisomal ABCD1 transporter of very long-chain fatty acids (VLCFAs). Its pathogenesis is incompletely understood. Here we characterize a nematode model of X-ALD with loss of the pmp-4 gene, the worm orthologue of ABCD1. These mutants recapitulate the hallmarks of X-ALD: i) VLCFAs accumulation and impaired mitochondrial redox homeostasis and ii) axonal damage coupled to locomotor dysfunction. Furthermore, we identify a novel role for PMP-4 in modulating lipid droplet dynamics. Importantly, we show that the mitochondria targeted antioxidant MitoQ normalizes lipid droplets size, and prevents axonal degeneration and locomotor disability, highlighting its therapeutic potential. Moreover, PMP-4 acting solely in the hypodermis rescues axonal and locomotion abnormalities, suggesting a myelin-like role for the hypodermis in providing essential peroxisomal functions for the nematode nervous system.

Clinical efficacy of haematopoietic stem cell transplantation for adult adrenoleukodystrophy

Accumulated experience supports the efficacy of allogenic haematopoietic stem cell transplantation in arresting the progression of childhood-onset cerebral form of adrenoleukodystrophy in early stages. For adulthood-onset cerebral form of adrenoleukodystrophy, however, there have been only a few reports on haematopoietic stem cell transplantation and the clinical efficacy and safety of that for adulthood-onset cerebral form of adrenoleukodystrophy remain to be established. To evaluate the clinical efficacy and safety of haematopoietic stem cell transplantation, we conducted haematopoietic stem cell transplantation on 12 patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy in a single-institution-based prospective study. Through careful prospective follow-up of 45 male adrenoleukodystrophy patients, we aimed to enrol patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy at early stages. Indications for haematopoietic stem cell transplantation included cerebral form of adrenoleukodystrophy or cerebello-brainstem form of adrenoleukodystrophy with Loes scores up to 13, the presence of progressively enlarging white matter lesions and/or lesions with gadolinium enhancement on brain MRI. Clinical outcomes of haematopoietic stem cell transplantation were evaluated by the survival rate as well as by serial evaluation of clinical rating scale scores and neurological and MRI findings. Clinical courses of eight patients who did not undergo haematopoietic stem cell transplantation were also evaluated for comparison of the survival rate. All the patients who underwent haematopoietic stem cell transplantation survived to date with a median follow-up period of 28.6 months (4.2–125.3 months) without fatality. Neurological findings attributable to cerebral/cerebellar/brainstem lesions became stable or partially improved in all the patients. Gadolinium-enhanced brain lesions disappeared or became obscure within 3.5 months and the white matter lesions of MRI became stable or small. The median Loes scores before haematopoietic stem cell transplantation and at the last follow-up visit were 6.0 and 5.25, respectively. Of the eight patients who did not undergo haematopoietic stem cell transplantation, six patients died 69.1 months (median period; range 16.0–104.1 months) after the onset of the cerebral/cerebellar/brainstem lesions, confirming that the survival probability was significantly higher in patients with haematopoietic stem cell transplantation compared with that in patients without haematopoietic stem cell transplantation (P = 0.0089). The present study showed that haematopoietic stem cell transplantation was conducted safely and arrested the inflammatory demyelination in all the patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy when haematopoietic stem cell transplantation was conducted in the early stages. Further studies are warranted to optimize the procedures of haematopoietic stem cell transplantation for adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy.

Progression of myelopathy in males with adrenoleukodystrophy: towards clinical trial readiness

Males with adrenoleukodystrophy develop progressive myelopathy causing severe disability later in life. No treatment is currently available, but new disease-modifying therapies are under development. Knowledge of the natural history of the myelopathy is of paramount importance for evaluation of these therapies in clinical trials, but prospective data on disease progression are lacking. We performed a prospective observational cohort study to quantify disease progression over 2 years of follow-up. Signs and symptoms, functional outcome measures and patient-reported outcomes were assessed at baseline, 1 and 2 years of follow-up. We included 46 male adrenoleukodystrophy patients (median age 45.5 years, range 16-71). Frequency of myelopathy at baseline increased with age from 30.8% (<30 years) to 94.7% (>50 years). Disease progression was measured in the patients who were symptomatic at baseline (n = 24) or became symptomatic during follow-up (n = 1). Significant progression was detected with the functional outcome measures and quantitative vibration measurements. Over 2 years of follow-up, Expanded Disability Status Score increased by 0.34 points (P = 0.034), Severity Scoring system for Progressive Myelopathy decreased by 2.78 points (P = 0.013), timed up-and-go increased by 0.82 s (P = 0.032) and quantitative vibration measurement at the hallux decreased by 0.57 points (P = 0.040). Changes over 1-year follow-up were not significant, except for the 6-minute walk test that decreased by 19.67 meters over 1 year (P = 0.019). None of the patient-reported outcomes were able to detect disease progression. Our data show that progression of myelopathy in adrenoleukodystrophy can be quantified using practical and clinically relevant outcome measures. These results will help in the design of clinical trials and the development of new biomarkers for the myelopathy of adrenoleukodystrophy.10.1093/brain/awy299_video1awy299media15995811923001.

Overall intact cognitive function in male X-linked adrenoleukodystrophy adults with normal MRI

BACKGROUND

Men with the hereditary peroxisomal disorder X-linked adrenoleukodystrophy (ALD) are at risk of developing inflammatory demyelinating lesions in the brain. In the absence of inflammatory (post-contrast enhancing) lesions on MRI cognitive function is considered spared, but some form of cognitive dysfunction may nevertheless be present. The aim of this cross-sectional study was to characterize cognitive functioning of ALD men with no or minimal MRI abnormalities, which will define cognitive functioning in this category of patients.

METHODS

A neuropsychological battery covering a broad range of cognitive domains, including language, verbal and non-verbal memory, visuoconstruction, executive functioning, and psychomotor speed, was used. Means and proportions of borderline and impaired T scores ≤36 were compared to the standardized norm group and a qualitative case-by-case analysis was performed for participants with T scores ≤36 within ≥2 domains. Patients with MRI abnormalities that were extensive (Loes score > 3) or showed enhancement post-contrast were excluded.

RESULTS

Thirty-three men participated (median age 44 years, range 19-71). Mean performance on verbal fluency was poorer in patients (45.70 ± 8.85 patients vs. 50 ± 10 standardized norm group, p = 0.009), as was the percentage of borderline and impaired scores on visuoconstruction (Beery VMI: 19% patients vs. 8% standardized norm group, p = 0.02; RCFT copy: 81% patients vs. 2% standardized norm group, p < 0.0005) and mental reaction time during a complex decision task (18% patients vs. 8% standardized norm group, p = 0.055). Moreover, 9/33 (27.3%) patients had T scores ≤36 within ≥2 domains.

CONCLUSIONS

Given the heterogeneous pattern of mostly borderline scores cognitive functioning seems not impaired in the vast majority of adult ALD males with no or minimal MRI abnormalities. However, borderline to impaired cognitive dysfunction was present in 27.3%, with the majority being borderline scores. Longitudinal studies will have to determine if this reflects early cerebral disease under the detection limit of MRI.

Gene-Based Approaches to Inherited Neurometabolic Diseases

In the last decade, the gene therapy (GT) field experienced a renaissance, thanks to crucial understandings and innovations in vector design, stem cell manipulation, conditioning protocols, and cell/vector delivery. These efforts were successfully coupled with unprecedented clinical results of the trials employing the newly developed technology and with the novel establishment of academic-industrial partnerships. A renewed and strengthened interest is rising in the development of gene-based approaches for inherited neurometabolic disorders with severe neurological involvement. Inherited metabolic disorders are monogenetic diseases caused by enzymatic or structural deficiencies affecting the lysosomal or peroxisomal metabolic activity. The metabolic defect can primarily affect the central nervous system, leading to neuronal death, microglial activation, inflammatory demyelination, and axonal degeneration. This review provides an overview of the GT strategies currently under clinical investigation for neurometabolic lysosomal and peroxisomal storage diseases, such as adrenoleukodystrophy and metachromatic leukodystrophy, as well as novel emerging indications such as mucopolysaccharidoses, gangliosidoses, and neuronal ceroid lipofuscinoses, with a comprehensive elucidation of the main features and mechanisms at the basis of a successful GT approach for these devastating diseases.

Hematopoietic Stem Cell Transplantation to Treat Leukodystrophies: Clinical Practice Guidelines from the Hunter's Hope Leukodystrophy Care Network

The leukodystrophies are a heterogeneous group of inherited diseases characterized by progressive demyelination of the central nervous system leading to devastating neurologic symptoms and premature death. Hematopoietic stem cell transplantation (HSCT) has been successfully used to treat certain leukodystrophies, including adrenoleukodystrophy, globoid leukodystrophy (Krabbe disease), and metachromatic leukodystrophy, over the past 30 years. To date, these complex patients have primarily been transplanted at a limited number of pediatric centers. As the number of cases identified through pregnancy and newborn screening is increasing, additional centers will be required to treat these children. Hunter's Hope created the Leukodystrophy Care Network in part to create and standardize high-quality clinical practice guidelines to guide the care of affected patients. In this report the clinical guidelines for the care of pediatric patients with leukodystrophies undergoing treatment with HSCT are presented. The initial transplant evaluation, determination of patient eligibility, donor selection, conditioning, supportive care, and post-transplant follow-up are discussed. Throughout these guidelines the need for early detection and treatment and the role of the partnership between families and multidisciplinary providers are emphasized.

[Haploidentical allogenetic hematopoietic stem cell transplantation for X-linked adrenoleukodystrophy]

OBJECTIVE

X-linked adrenoleukodystrophy (ALD) is a severe inherited disorder leading to rapid neurological deterioration and premature death. Allogeneic hematopoietic stem cell transplantation (HSCT) is still the only treatment that halts the neurologic symptoms in ALD. However, many patients lack suitable human leukocyte antigen (HLA) matched related donors and must rely on alternative donors for a source of stem cells. The purpose of this study was to explore the outcomes of haploidentical allogeneic stem cell transplantation for ALD patients.

METHODS

Between December 2014 and December 2018, eight children with ALD lacking HLA matched related or unrelated donors were treated with haploidentical allogeneic hematopoietic stem cell transplantation. The patients received conditioning regimen with busulfan 9.6 mg/kg, cyclophosphamide 200 mg/kg and fludarabine 90 mg/m². Graft-versus-host disease (GVHD) prophylaxis consisted of anti-human thymocyte globulin, cyclosporine A, mycophenolate mofetil and short course of methotrexate.

RESULTS

All the 8 children received allogeneic stem cell transplants from their fathers. The median age of the recipients was 8 (range: 5-12) years. The median age of the donors was 36 (range: 32-40) years. All the recipients received granulocyte colony-stimulating factor (G-CSF) mobilized bone marrow and peripheral blood-derived stem cells. The median number of total mononuclear cells dose and CD34+ dose was 10.89 (range: 9.40-12.16)×10⁸/kg and 7.06 (range: 0.74-7.80)×10⁶/kg, respectively. Neutrophil engraftment occurred a median of 11 days (range:8-13 days) after transplantation. Platelet engraftment occurred a median of 10 days (range:8-12 days) after transplantation. All the patients achieved complete donor chimerism at the time of engraftment. Four patients had grades II-IV acute GVHD and 1 had chronic graft-versus-host disease. No severe chronic GVHD occurred. Among all the children, 2 had cytomegalovirus (CMV) DNAemia and 2 Epstein-Barr virus (EBV) DNAemia. Overall, seven of them survived and had no major complications related to transplantation. One died of cerebral hernia after epilepsy 125 days after transplantation.

CONCLUSION

The preliminary observation demonstrates that haploidentical allogeneic stem cell transplantation with this novel regimen could successfully achieve full donor chimerism in ALD patients. According to our experience, haploidentical allogeneic hematopoietic stem cell transplantation is safe and feasible in the treatment of X-linked adrenoleukodystrophy.

Allogeneic hematopoietic stem cell transplantation with myeloablative conditioning for adult cerebral X-linked adrenoleukodystrophy

The adult cerebral form of X-linked adrenoleukodystrophy (ACALD), an acute inflammatory demyelinating disease, results in a rapidly progressive neurodegeneration, typically leading to severe disability or death within a few years after onset. We have treated 15 men who had developed ACALD with allogeneic hematopoietic stem cell transplantation (HSCT) from matched donors after myeloablative conditioning with busulfan and cyclophosphamide. All patients engrafted and 11 survived (estimated survival 73 ± 11%), 8 with stable cognition and 7 of them with stable motor function (estimated event-free survival 36 ± 17%). Death after transplantation occurred within the first year after HSCT and was caused either primarily by infection (N = 3) or due to disease progression triggered by infection (N = 1). Patients with minor myelopathic symptoms (N = 4) or with no or mild cerebral symptoms pre-transplant (N = 7) had an excellent outcome. In contrast, no patient with major neurological symptoms associated with an extensive involvement of pyramidal tract fibres in the internal capsule (N = 5) survived without cognitive deterioration. Notably, early leukocyte recovery was associated with dismal outcome for yet unknown reasons. All 10 tested survivors showed a reduction of plasma hexacosanoic acid (C26:0) in the absence of Lorenzo's oil. Over time, the event-free survival could be improved from 2 out of 8 patients (25%) before 2013 to 5 out of 7 patients (71%) thereafter. Therefore, allogeneic HSCT appears to be a suitable treatment option for carefully selected ACALD patients when transplanted from matched donors after myeloablative, busulfan-based conditioning.

The Natural History of Adrenal Insufficiency in X-Linked Adrenoleukodystrophy: An International Collaboration

CONTEXT

Primary adrenal insufficiency is an important clinical manifestation of X-linked adrenoleukodystrophy (ALD). Other manifestations include spinal cord disease and/or inflammatory demyelinating cerebral disease. Implementation of newborn screening requires natural history data to develop follow-up recommendations.

OBJECTIVE

To delineate the natural history of adrenal insufficiency in male patients with ALD and to assess associations between the risk for developing adrenal insufficiency, spinal cord disease, or cerebral disease and plasma C26:0/C22:0 and C24:0/C22:0 ratios, which are diagnostic biomarkers for ALD.

DESIGN

Retrospective review of medical records.

SETTING

Two international tertiary referral centers of expertise for ALD.

PATIENTS

Male patients with ALD followed at the centers between 2002 and 2016.

MAIN OUTCOME MEASURES

The primary endpoint was adrenal insufficiency; secondary endpoints were spinal cord and cerebral disease.

RESULTS

Data on 159 male patients was available. The probability of developing adrenal insufficiency was described with survival analysis. Median time until adrenal insufficiency was 14 years (95% CI, 9.70 to 18.30 years). The cumulative proportion of patients who developed adrenal insufficiency was age-dependent and highest in early childhood [0 to 10 years, 46.8% (SEM 0.041%); 11 to 40 years, 28.6% (SEM, 0.037%); >40 years, 5.6% (SEM, 0.038%)]. No association between clinical manifestations and plasma ratios was detected with Cox model or Spearman correlation.

CONCLUSIONS

Lifetime prevalence of adrenal insufficiency in male patients with ALD is ~80%. Adrenal insufficiency risk is time-dependent and warrants age-dependent follow-up. Besides on-demand testing if symptoms manifest, we suggest a minimum of adrenal testing every 4 to 6 months for patients age ≤10 years, annual testing for those age 11 to 40 years, and solely on-demand testing for those age >40 years.

Characteristics of Japanese patients with X-linked adrenoleukodystrophy and concerns of their families from the 1st registry system

OBJECTIVE

Early diagnosis is critical in achieving the best outcome following hematopoietic stem cell transplantation (HSCT) for X-linked adrenoleukodystrophy (X-ALD). We used a questionnaire to gather detailed clinical information and information regarding the anxieties of patients' families using the registry system for X-ALD.

METHODS

We and the patients' families established the registry system for X-ALD in Japan. We created a questionnaire and distributed it to the patients' families.

RESULTS

Questionnaire data from 28 patients were collected. The median age at enrollment was 14.5 years. The most common type of X-ALD was the childhood cerebral form (22 patients, 78.6%). The median age at symptom onset was 7.4 years. Frequently reported initial observations were behavior or character changes (46.4%), gait disturbances (42.9%), strabismus (39.3%), reduced academic ability (32.1%), failing vision (21.4%), a positive family history (21.4%), clumsiness (17.9%), hearing disturbances (17.9%), convulsions (10.7%), and suspected psychiatric disorders (10.7%). The median duration from symptom onset to diagnosis was 12 months. The families of 12 patients (42.9%) with X-ALD who received HSCT were satisfied regardless of its effectiveness. Common concerns of patients' families were worries regarding heritability of X-ALD (78.6%), present symptoms (57.1%), frequent hospital visits (42.9%), problems at school or work (42.9%), economic issues (35.7%), and limited information regarding X-ALD (32.1%).

CONCLUSION

This is the first study clarifying the clinical characteristics of X-ALD and the concerns of patients' families using the registry system. Investigation of rare diseases using registry systems is very valuable for the understanding of such conditions.

Allogeneic stem cell transplantation with reduced intensity conditioning for patients with adrenoleukodystrophy

Objective

The prognosis of adrenoleukodystrophy (ALD)with neurological involvement is generally dismal; however, allogeneic stem cell transplantation (SCT) is recognized as effective to stabilize or improve the clinical symptoms of ALD. Herein, we report the clinical outcomes of patients with ALD who consecutively underwent allogeneic stem cell transplantation with reduced intensity conditioning at our institution.

Patients

Sixteen patients with ALD, who were symptomatic (n = 14) or presymptomatic (n = 2), received SCT from 2010 to 2016. The stem cell source was cord blood (n = 14), or bone marrow from a human leukocyte antigen identical sibling (n = 2). The conditioning regimen prior to transplantation was reduced intensity and consisted of fludarabine (125 mg/m²), melphalan (140 mg/m²) and low dose total body irradiation (TBI) of 4Gy (n = 15) or 3Gy (n = 1).

Results

Primary engraftment was obtained in 11 patients, and 4 of the 5 patients who lost the primary graft received a second cord blood transplantation and were engrafted. Five years overall and event-free survival were 90.9% and 61.1% respectively, with a median of 45 months (range 16–91). Loes score stabilized or improved by 18 months after transplantation except for patients with internal capsule involvement.

Conclusion

Allogeneic SCT with reduced intensity conditioning for patients with ALD was safely performed without major transplant-related complications even in symptomatic patients and neurological symptoms were stabilized after SCT in patients without internal capsule involvement.

Transplantation as disease modifying therapy in adults with inherited metabolic disorders

Transplantation is an established disease modifying therapy in selected children with certain inherited metabolic diseases (IMDs). Transplantation of hematopoietic stem cells or solid organs can be used to partially correct the underlying metabolic defect, address life threatening disease manifestations (such as neutropenia) or correct organ failure caused by the disease process. Much less information is available on the use of transplantation in adults with IMDs. Transplantation is indicated for the same IMDs in adults as in children. Despite similar disease specific indications, the actual spectrum of diseases for which transplantation is used differs between these age groups and this is partly related to the natural history of disease. There are diseases (such as urea cycle defects and X-linked adrenoleukodystrophy) for which transplantation is recommended for selected symptomatic patients as a treatment strategy in both adults and children. In those diseases, the frequency with which transplantation is used in adults is lower than in children and this may be related in part to a reduced awareness of transplantation as a treatment strategy amongst adult clinicians as well as limited donor availability and allocation policies which may disadvantage adult patients with IMDs. Risks of transplantation and disease-specific prognostic factors influencing outcomes also differ with age. We review the use of transplantation as a disease modifying strategy in adults focusing on how this differs from use in children to highlight areas for future research.

Potential Risks to Stable Long-term Outcome of Allogeneic Hematopoietic Stem Cell Transplantation for Children With Cerebral X-linked Adrenoleukodystrophy

IMPORTANCE

Allogeneic hematopoietic stem cell transplantation is the standard intervention for childhood cerebral X-linked adrenoleukodystrophy. However, the pretransplant conditions, demyelination patterns, complications, and neurological outcomes of this therapy are not well characterized.

OBJECTIVES

To identify the risks to stable neurocognitive survival after hematopoietic stem cell transplantation and to describe subgroups of patients with distinct clinical long-term outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This case series analyzed the treatment and outcome of a cohort of 36 boys who underwent hematopoietic stem cell transplantation at Charité Universitätsmedizin Berlin, Germany, between January 1, 1997, and October 31, 2014. Case analysis was performed from January 1, 2016, through November 30, 2017. During this retrospective review, the adrenoleukodystrophy-disability rating score and the neurological function score were used. Demyelinating lesions in the brain were quantified by the Loes score.

MAIN OUTCOMES AND MEASURES

Overall survival, survival without major functional disabilities, and event-free survival were analyzed. Patients' clinical symptoms, demyelination patterns, and stem cell source were stratified.

RESULTS

Of the 36 boys who underwent hematopoietic stem cell transplantation, the median (range) age was 7.2 (4.2-15.4) years; 18 were presymptomatic and 18 were symptomatic. Twenty-seven patients (75%) were alive at a median (interquartile range [IQR]) follow-up of 108 (40-157) months. Sixteen of 18 presymptomatic patients (89%) survived, and 13 (72%) had an event-free survival with a median (IQR) survival time of 49 (37-115) months. Among the symptomatic patients, 11 of 18 (61%) survived, but only 1 was an event-free survival (6%) (median [IQR] time, 9 [3-22] months). Of the 9 patients who received a bone marrow transplant from a matched family donor, all survived. Among the 36 patients, 6 disease-related deaths (17%) and 3 transplant-related deaths (8%) occurred. Deaths from disease progression (n = 6) occurred only in patients with demyelination patterns other than parieto-occipital. In total, 18 patients (50%) displayed limited parieto-occipital (Loes score <9) or frontal (Loes score <4) demyelination before transplant (favorable). None of these patients died of progressive disease or developed major functional disabilities, 15 of them were characterized by stable neuroimaging after the transplant, and event-free survival was 77% (95% CI, 60%-100%). In contrast, the other 18 patients with more extended parieto-occipital demyelination (n = 6), frontal involvement (n = 4), or other demyelination patterns (n = 8) progressed (unfavorable): 13 patients developed epilepsy and 10 developed major functional disabilities, and their event-free survival was 0%. This newly defined neuroimaging assessment correlated best with neurocognitive deterioration after transplant (hazard ratio, 16.7; 95% CI, 4.7-59.6).

CONCLUSIONS AND RELEVANCE

All patients with favorable neuroimaging who received matched bone marrow remained stable after transplant, while some of the other patients developed major functional disabilities. Newborn screening for the disease and regular neuroimaging are recommended, and patients who lack a matched bone marrow donor may need to find new therapeutic options.

[Overview of X-linked adrenoleukodystrophy in Morocco: results of the implementation of the program of clinical and biological diagnosis]

Introduction

L'adrénoleucodystrophie liée à l'X (X-ALD) est une maladie neurodégénérative sévère, due à des mutations du gène ABCD1. Elle se manifeste par une atteinte du système nerveux central et périphérique, une insuffisance surrénalienne et une atteinte des testicules chez le garçon. Son diagnostic repose sur le dosage des Acides Gras à Très Longue Chaine. Le diagnostic précoce est d'une grande importance puisque il définit l'accessibilité aux traitements selon le stage de la maladie.

Méthodes

Nous avons mis en place un programme de diagnostic de l'X-ALD au Maroc au niveau de l'Hôpital d'enfants et du Laboratoire centrale des maladies héréditaires et du métabolisme de Rabat. Le programme s'articule sur trois axes à savoir : le recrutement des patients, le diagnostic et la sensibilisation. Le diagnostic s'effectue selon trois protocoles : un protocole pour les cas symptomatiques, un deuxième pour les cas asymptomatiques et un troisième pour les femmes hétérozygotes.

Résultats

Durant trois ans après la mise en place de notre programme de diagnostic de l'Adrénoleucodystrophie liée à l'X, nous avons diagnostiqué la maladie chez sept familles, avec neuf garçons et trois femmes hétérozygotes. Tous les enfants diagnostiqués présentaient la forme cérébrale démyélinisante. Toutes les femmes hétérozygotes étaient asymptomatiques. Une prise en charge thérapeutique a été mise place selon la symptomatologie de chaque cas.

Conclusion

l'X-ALD est une maladie rare. Notre programme de diagnostique a permis de diagnostiquer un nombre important de cas, ce qui montre son importance. Les compagnes de sensibilisation auprès des professionnels permettront de mieux comprendre la maladie et mieux la diagnostiquer et ainsi donner accès à un nombre plus élevé de patients.

Post-transplant adaptive function in childhood cerebral adrenoleukodystrophy

Objective

Hematopoietic stem cell transplantation (HSCT) is the only treatment known to slow or halt inflammatory demyelination among boys with the cerebral form of X‐linked adrenoleukodystrophy (cALD), a devastating childhood condition affecting the central nervous system. HSCT can lead to a range of adverse outcomes including fatality. Previous studies have examined the potential predictors of post‐HSCT survival and neurologic functioning. However, little is known about patients' daily‐life adaptive functional outcomes (i.e., ability to communicate, maintain social relationships, and independently execute tasks of daily living). The purpose of this retrospective cohort study was to identify which patient characteristics and treatment‐related variables predict long‐term adaptive function among the survivors of HSCT for cALD.

Methods

We obtained caregiver ratings of adaptive functioning of 65 transplant survivors at an average of 4.6 years (range: 1.0–24.1 years) post‐HSCT. Using linear regression with penalized maximum likelihood estimation, we modeled the relative contribution of pre‐transplant neurocognitive test performance, MRI severity, transplant regimen, and length of time since transplant on patient adaptive functioning outcomes.

Results

Higher radiographic disease severity and poorer performance on baseline neurocognitive tests requiring fine motor skills and visual perception were associated with inferior adaptive functioning after HSCT. Use of radiation during the transplant preparative regimen also predicted poorer adaptive outcomes.

Interpretation

In addition to radiological disease severity, baseline neurocognitive test performance is associated with post‐transplant adaptive functional outcomes. Neurocognitive measures may play an important role in prognostic counseling and post‐transplant treatment planning for patients considering HSCT for cALD.