Economic Burden of Gaucher Disease at a Tertiary Care Public Hospital in Mumbai

OBJECTIVES

To estimate the economic burden of patients diagnosed with Gaucher disease at a public hospital from a societal perspective.

METHODS

Data from 30 Gaucher patients visiting the Genetic Clinic of the Department of Pediatrics at the study site in Mumbai was analyzed between January 2019 and January 2021. A cost of illness analysis was undertaken to estimate direct, indirect and intangible costs. Costs in treated and treatment naive groups were compared.

RESULTS

The total cost (direct and indirect) for 30 patients was ₹25,45,74,743/- (3440199.2 USD). Majority of this cost (99.8%) was due to direct costs of which medications [Enzyme replacement therapy (ERT) and Substrate reduction therapy (SRT)] constituted 98.8%. The notional cost was ₹1,43,94,695. Total costs of 14 treated patients were ₹25,29,67,279 and 16 treatment naive patients were ₹16,15,064 with a ratio of 157:1. Direct costs and cost of school absenteeism were significantly higher in the treated subgroup. Overall, direct, total costs and costs of school absenteeism were significantly associated with age and disease duration.

CONCLUSIONS

The economic burden of Gaucher disease is a staggering amount. This is an underestimate, as the expenses are highly subsidized in a public health facility. The highest contributor to cost component was direct costs, especially medication costs. Against the backdrop of the National Policy for Rare Diseases, resource allocation towards Gaucher disease should consider short term measures for judicious funding or reimbursement of disease-specific therapy and long-term cost-effective measures for promoting preventive strategies as the most practically feasible solution to reduce this economic burden.

Long-Term Outcomes of Disease Modifying Therapies in Gaucher Disease

OBJECTIVES

To study clinical response to treatment with enzyme replacement therapy (ERT) and substrate reduction therapy (SRT) in a cohort of Gaucher disease.

METHODS

Retrospective data of 8 patients of Gaucher disease was compiled. The treatment included all three currently available enzyme replacement therapies as well as substrate reduction therapy with Eliglustat. The relevant blood investigations were done in follow-up visits. The assessment of the effects of long-term treatment over varying periods up to 13 y was done with various issues related to the course of therapy documented.

RESULTS

Improvement in hematological parameters was seen in all patients. Reduction of spleen size occurred in 7 of 8 patients (87.5%). One patient had 2 successful pregnancies while on therapy. A distinct patient with type 3 Gaucher disease developed complication in the form of Gaucheroma within the spleen.

CONCLUSIONS

Awareness about the disease and the efficacy of the therapies amongst pediatricians will help in early diagnosis and better outcomes. The available therapies have changed the outcome of the patients and improved the quality of life in patients with Gaucher disease. The data of Indian patients is important at this juncture when under Rare Disease Policy, government funding has become available for ERT for Gaucher disease patients in India.

The treatment of biochemical genetic diseases: From substrate reduction to nucleic acid therapies

Newborn screening (NBS) began a revolution in the management of biochemical genetic diseases, greatly increasing the number of patients for whom dietary therapy would be beneficial in preventing complications in phenylketonuria as well as in a few similar disorders. The advent of next generation sequencing and expansion of NBS have markedly increased the number of biochemical genetic diseases as well as the number of patients identified each year. With the avalanche of new and proposed therapies, a second wave of options for the treatment of biochemical genetic disorders has emerged. These therapies range from simple substrate reduction to enzyme replacement, and now ex vivo gene therapy with autologous cell transplantation. In some instances, it may be optimal to introduce nucleic acid therapy during the prenatal period to avoid fetopathy. However, as with any new therapy, complications may occur. It is important for physicians and other caregivers, along with ethicists, to determine what new therapies might be beneficial to the patient, and which therapies have to be avoided for those individuals who have less severe problems and for which standard treatments are available. The purpose of this review is to discuss the "Standard" treatment plans that have been in place for many years and to identify the newest and upcoming therapies, to assist the physician and other healthcare workers in making the right decisions regarding the initiation of both the "Standard" and new therapies. We have utilized several diseases to illustrate the applications of these different modalities and discussed for which disorders they may be suitable. The future is bright, but optimal care of the patient, including and especially the newborn infant, requires a deep knowledge of the disease process and careful consideration of the necessary treatment plan, not just based on the different genetic defects but also with regards to different variants within a gene itself.

Venglustat, an orally administered glucosylceramide synthase inhibitor: Assessment over 3 years in adult males with classic Fabry disease in an open-label phase 2 study and its extension study

Venglustat inhibits the enzymatic conversion of ceramide to glucosylceramide, reducing available substrate for the synthesis of more complex glycosphingolipids. It offers a potential new approach to the treatment of patients with Fabry disease (α-Gal A deficiency), in whom progressive accumulation of such glycosphingolipids, including globotriaosylceramide (GL-3), in the lysosomes of a wide range of cell types often leads to vital organ complications in adulthood. An international, open-label, single-arm, Phase 2a uncontrolled 26-week clinical study (NCT02228460) and a 130-week extension study (NCT02489344) were conducted to assess the safety, pharmacodynamics, pharmacokinetics, and exploratory efficacy of 15 mg once daily oral venglustat in treatment-naïve adult male patients with classic Fabry disease. Of 11 patients (18-37 years old) who initially enrolled, nine completed the 26-week study and seven completed the extension study. A total of 169 treatment-emergent adverse events (TEAEs) were reported by nine patients, the majority being mild (73%) and unrelated to the study drug (70%). Nine serious TEAEs (serious adverse events) and 11 severe TEAEs, including a self-harm event, were reported. No deaths or treatment-related life-threatening adverse events were reported. Skin GL-3 scores in superficial skin capillary endothelium (SSCE), estimated by light microscopy, were unchanged from baseline at Week 26 in five patients, decreased in three patients, and increased in one patient. There was no significant change in GL-3 scores or significant shift in grouped GL-3 scores. Five of six patients had reductions from baseline in GL-3 score at the end of the extension study. At Weeks 26 and 156 the mean (standard deviation) changes from baseline in the fraction of the volume of SSCE cytoplasm occupied by GL-3 inclusions, measured by electron microscopy unbiased stereology, were - 0.06 (0.03) (p = 0.0010) and - 0.12 (0.04) (p = 0.0008), respectively. Venglustat treatment reduced markers in the synthetic and degradative pathway of major glycosphingolipids; proximal markers reduced rapidly and more distal markers (plasma GL-3 and globotriaosylsphingosine) reduced progressively. There were no biochemical or histological indications of progression of Fabry disease over 3 years of follow-up. These findings confirm target engagement and the pharmacodynamic effects of venglustat in adult males with classic Fabry disease. However, further clinical evaluation in larger studies is needed to determine efficacy and safety.

Long-term effects of eliglustat on skeletal manifestations in clinical trials of patients with Gaucher disease type 1

PURPOSE

Most patients with Gaucher disease have progressive and often disabling skeletal manifestations. We examined the long-term effect of eliglustat treatment on bone outcomes in clinical trials in adults with Gaucher disease type 1.

METHODS

Data from 4 completed phase 2 and 3 trials were evaluated in treatment-naïve patients or patients switching to eliglustat from enzyme replacement therapy (ERT).

RESULTS

Overall, 319 of 393 (81%) eliglustat-treated patients remained in their trials until completion or commercial eliglustat became available. Mean eliglustat treatment duration ranged from 3.3 to 6.5 years. In treatment-naïve patients and ERT-switch patients, frequency and severity of bone pain decreased during eliglustat treatment. Mean lumbar spine T-scores shifted from abnormal to normal in treatment-naïve patients and remained in the healthy reference range or improved modestly in ERT-switch patients. Mean total bone marrow burden score shifted from marked-to-severe to moderate in treatment-naïve patients and remained moderate in ERT-switch patients. MIP-1β (marker of active bone disease) was elevated at baseline and decreased to the healthy reference range in treatment-naïve patients and remained in the healthy reference range among ERT-switch patients.

CONCLUSION

These findings confirm the long-term efficacy of eliglustat on skeletal complications of Gaucher disease in treatment-naïve and ERT-switch patients.

The new horizons for treatment of Late-Onset Pompe Disease (LOPD)

Late-onset Pompe disease (LOPD) is a genetic myopathy causing skeletal muscle weakness and severe respiratory impairment, due to the deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) leading to lysosomal glycogen accumulation along with other complex pathophysiological processes. A major step for treatment of Pompe disease was reached in 2006 with the marketing of alglucosidase alfa, a first enzyme replacement therapy (ERT) that showed a significant motor and respiratory benefit. However, efficacy of alglucosidase alfa is limited in LOPD with a loss of efficacy over time, promoting research on new treatments. Next-generation ERT are new enzymes biochemically modified to increase the uptake of exogenous enzyme by target tissues, and the benefit of two recombinant enzymes (avalglucosidase alfa and cipaglucosidase alfa) has been recently studied in large phase III clinical trials, the latest combined with miglustat. Several innovative therapies, based on GAA gene transfer, antisense oligonucleotides or inhibition of glycogen synthesis with substrate reduction therapy, are currently under study, but are still at an early stage of development. Overall, active research for new treatments raises hope for LOPD patients but challenges remain for the clinician with the need for reliable efficacy assessment tools, long-term registry data, and evidence-based recommendations for the best use of these new molecules recently available or under development.

Dysregulated DNA methylation in the pathogenesis of Fabry disease

Fabry disease is an X-linked lysosomal storage disorder caused by a deficiency of α-galactosidase A and subsequent accumulation of glycosphingolipids with terminal α-D-galactosyl residues. The molecular process through which this abnormal metabolism of glycosphingolipids causes multisystem dysfunction in Fabry disease is not fully understood. We sought to determine whether dysregulated DNA methylation plays a role in the development of this disease. In the present study, using isogenic cellular models derived from Fabry patient endothelial cells, we tested whether manipulation of α-galactosidase A activity and glycosphingolipid metabolism affects DNA methylation. Bisulfite pyrosequencing revealed that changes in α-galactosidase A activity were associated with significantly altered DNA methylation in the androgen receptor promoter, and this effect was highly CpG loci-specific. Methylation array studies showed that α-galactosidase A activity and glycosphingolipid levels were associated with differential methylation of numerous CpG sites throughout the genome. We identified 15 signaling pathways that may be susceptible to methylation alterations in Fabry disease. By incorporating RNA sequencing data, we identified 21 genes that have both differential mRNA expression and methylation. Upregulated expression of collagen type IV alpha 1 and alpha 2 genes correlated with decreased methylation of these two genes. Methionine levels were elevated in Fabry patient cells and Fabry mouse tissues, suggesting that a perturbed methionine cycle contributes to the observed dysregulated methylation patterns. In conclusion, this study provides evidence that α-galactosidase A deficiency and glycosphingolipid storage may affect DNA methylation homeostasis and highlights the importance of epigenetics in the pathogenesis of Fabry disease and, possibly, of other lysosomal storage disorders.

Evolving therapies in neuronopathic LSDs: opportunities and challenges

Lysosomal storage disorders (LSD) are multisystemic progressive disorders caused by genetic mutations involving lysosomal function. While LSDs are individually considered rare diseases, the overall true prevalence of these disorders is likely higher than our current estimates. More than two third of the LSDs have associated neurodegeneration and the neurological phenotype often defines the course of the disease and treatment outcomes. Addressing the neurological involvement in LSDs has posed a significant challenge in the rapidly evolving field of therapies for these diseases. In this review, we summarize current approaches and clinical trials available for patients with neuronopathic lysosomal storage disorders, exploring the opportunities and challenges that have emerged with each of these.

Recommendations for oral treatment for adult patients with type 1 Gaucher disease

This work is a review of the scientific evidence on the oral treatment of adult patients with Gaucher disease type 1 (GD1) with a clinical guideline format according to the Agree II regulations. It describes the main differences between the two oral treatments currently available for treating this disease (miglustat and eliglustat). This review reminds us that the criteria for starting oral treatment in patients with GD1 must be assessed individually. Although miglustat and eliglustat are both glucosylceramide synthase (GCS) enzyme inhibitors, they have different mechanisms of action and pharmacological properties and should never be considered equivalent. Miglustat is indicated in patients with non-severe GD1 who cannot receive other first-line treatments, while eliglustat is indicated as first-line treatment for patients with GD1 of any severity without the need for prior stabilization with enzyme replacement therapy (ERT). It is important to emphasize that in order to start treatment with eliglustat, we must know the CYP2D6 metabolic phenotype and its association with drugs metabolized through the CYP2D6 and CYP3A4 cytochromes-or alternatively those that use P-Glycoprotein must be evaluated on an individual basis. During pregnancy, the use of eliglustat should be avoided; only ERT can be used. Unlike miglustat, whose adverse effects have limited its use, eliglustat has not only demonstrated similar efficacy to ERT but has also been shown to improve the quality of life of patients with GD1.

A novel brain-penetrant oral UGT8 inhibitor decreases in vivo galactosphingolipid biosynthesis in murine Krabbe disease

Krabbe disease is a rare, inherited neurodegenerative disease due to impaired lysosomal β-galactosylceramidase (GALC) activity and formation of neurotoxic β-galactosylsphingosine ('psychosine'). We investigated substrate reduction therapy with a novel brain-penetrant inhibitor of galactosylceramide biosynthesis, RA 5557, in twitcher mice that lack GALC activity and model Krabbe disease. This thienopyridine derivative selectively inhibits uridine diphosphate-galactose glycosyltransferase 8 (UGT8), the final step in the generation of galactosylceramides which are precursors of sulphatide and, in the pathological lysosome, the immediate source of psychosine. Administration of RA 5557, reduced pathologically elevated psychosine concentrations (72-86%) in the midbrain and cerebral cortex in twitcher mice: the inhibitor decreased galactosylceramides by about 70% in midbrain and cerebral cortex in mutant and wild type animals. Exposure to the inhibitor significantly decreased several characteristic inflammatory response markers without causing apparent toxicity to myelin-producing cells in wild type and mutant mice; transcript abundance of oligodendrocyte markers MBP (myelin basic protein) and murine UGT8 was unchanged. Administration of the inhibitor before conception and during several breeding cycles to mice did not impair fertility and gave rise to healthy offspring. Nevertheless, given the unchanged lifespan, it appears that GALC has critical functions in the nervous system beyond the hydrolysis of galactosylceramide and galactosylsphingosine. Our findings support further therapeutic exploration of orally active UGT8 inhibitors in Krabbe disease and related galactosphingolipid disorders. The potent thienopyridine derivative with effective target engagement here studied appears to have an acceptable safety profile in vivo; judicious dose optimization will be needed to ensure efficacious clinical translation.

In-depth phenotyping for clinical stratification of Gaucher disease

BACKGROUND

The Gaucher Investigative Therapy Evaluation is a national clinical cohort of 250 patients aged 5-87 years with Gaucher disease in the United Kingdom-an ultra-rare genetic disorder. To inform clinical decision-making and improve pathophysiological understanding, we characterized the course of Gaucher disease and explored the influence of costly innovative medication and other interventions. Retrospective and prospective clinical, laboratory and radiological information including molecular analysis of the GBA1 gene and comprising > 2500 variables were collected systematically into a relational database with banking of collated biological samples in a central bioresource. Data for deep phenotyping and life-quality evaluation, including skeletal, visceral, haematological and neurological manifestations were recorded for a median of 17.3 years; the skeletal and neurological manifestations are the main focus of this study.

RESULTS

At baseline, 223 of the 250 patients were classified as type 1 Gaucher disease. Skeletal manifestations occurred in most patients in the cohort (131 of 201 specifically reported bone pain). Symptomatic osteonecrosis and fragility fractures occurred respectively in 76 and 37 of all 250 patients and the first osseous events occurred significantly earlier in those with neuronopathic disease. Intensive phenotyping in a subgroup of 40 patients originally considered to have only systemic features, revealed neurological involvement in 18: two had Parkinson disease and 16 had clinical signs compatible with neuronopathic Gaucher disease-indicating a greater than expected prevalence of neurological features. Analysis of longitudinal real-world data enabled Gaucher disease to be stratified with respect to advanced therapies and splenectomy. Splenectomy was associated with an increased hazard of fragility fractures, in addition to osteonecrosis and orthopaedic surgery; there were marked gender differences in fracture risk over time since splenectomy. Skeletal disease was a heavy burden of illness, especially where access to specific therapy was delayed and in patients requiring orthopaedic surgery.

CONCLUSION

Gaucher disease has been explored using real-world data obtained in an era of therapeutic transformation. Introduction of advanced therapies and repeated longitudinal measures enabled this heterogeneous condition to be stratified into obvious clinical endotypes. The study reveals diverse and changing phenotypic manifestations with systemic, skeletal and neurological disease as inter-related sources of disability.

Incremental biomarker and clinical outcomes after switch from enzyme therapy to eliglustat substrate reduction therapy in Gaucher disease

In Gaucher disease (GD), genetic deficiency of acid β-glucosidase leads to accumulation of its substrate glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Lipid-laden cells, most prominently seen as macrophages engorged with GlcCer and GlcSph-laden lysosomes, trigger chronic metabolic inflammation and multisystemic phenotypes. Among the pleiotropic effects of inflammatory cascades, the induction of glucosylceramide synthase accentuates the primary metabolic defect. First-line therapies for adults with GD type 1 include Enzyme Replacement Therapy (ERT) and eliglustat Substrate Reduction Therapy (SRT). The ENCORE phase 3 clinical trial of eliglustat demonstrated non-inferiority compared to ERT. It is not known whether switching stable patients from long-term ERT to SRT results in the incremental reversal of the disease phenotype and its surrogate indicators. Herein, we report real-world experience from a single tertiary referral center of 38 adult GD type 1 patients, stable on long-term ERT (mean 13.3 years), who switched to eliglustat SRT (mean 3.1 years). After switch to SRT, there was significant reduction in spleen volume (P = 0.003) while liver volume, which was normal at baseline, remained unchanged. Platelet counts increased significantly (P = 0.026). Concomitantly, there was reduction of three validated biomarkers of Gaucher disease activity: plasma GlcSph decreased from 63.7 ng/ml (95% CI, 37.6-89.8) to 26.1 ng/ml (95% CI, 15.7-36.6) (P < 0.0001); chitotriosidase fell from 1136.6 nmol/ml/h (95% CI, 144.7-2128.6) to 466.9 nmol/ml/h (95% CI, 209.9-723.9) (P = 0.002); and glycoprotein non-metastatic melanoma B (gpNMB) decreased from 59.3 ng/ml (95% CI, 39.7-78.9) to 43.6 ng/ml (95% CI, 30.7-56.6) (P = 0.0006). There were no episodes of avascular necrosis or fractures in patients on SRT. Patients reported favorable experiences of switching from alternate week infusions to oral therapy. Collectively, these results demonstrate that the switch to eliglustat SRT from ERT leads to incremental response, even in stable patients after long-term ERT.

New treatment for myocardial diseases

Treatment of myocardial diseases with renin-angiotensin system inhibitors and β-blockers has greatly contributed to improving prognosis. However, these treatments are non-specific, and with the exception of some treatments, radical treatments according to the cause of each disease have not been developed until recent years. But in the past decade, more specific and more upstream treatments based on the molecular mechanism of disease onset have been developed and are emerging. Some of the effects have been shown in clinical practice and already approved. This article outlines the mechanism of action and clinical data of novel therapeutic agents specific for myocardial diseases such as dilated cardiomyopathy, hypertrophic cardiomyopathy, Fabry disease, cardiac amyloidosis, and myocarditis. In the future, we hope that the molecular mechanisms will be further elucidated and new and upstream treatment methods will be developed.

Therapeutic advances in Fabry disease: The future awaits

Fabry disease (FD) is an X-linked disorder caused by mutations in GLA gene responsible for coding of the lysosomal enzyme alpha-galactosidase A(α-GAL). The resultant accumulation of globotriaosylceramide (Gb-3) leads to multisystemic disease including progressive chronic kidney disease, hypertrophic cardiomyopathy, stroke, angiokeratomas and corneal whorls. Current treatments include enzyme replacement therapy (ERT), along with recent advent of chaperone therapy. ERT has not shown to have dramatic improvement in outcomes for all organ systems, with benefit mostly seen in kidney disease and reduction in left ventricular hypertrophy. ERT, however, is associated with formation of anti-drug antibodies and requirement of long-term venous access, while chaperone therapy can only be used in amenable mutations. A multitude of therapies are now under investigation in various phases of clinical trials. These include pegylated form of α-GAL (pegunigalsidase alpha), gene therapy (both in-vivo and ex-vivo methods), mRNA therapy (inducing production of α-GAL) and substrate reduction therapy (inhibitors of glucosylceramide synthase leading to reduction of Gb-3). This review encapsulates literature pertaining to current and investigational therapies for FD.

The lysine degradation pathway: Subcellular compartmentalization and enzyme deficiencies

Lysine degradation via formation of saccharopine is a pathway confined to the mitochondria. The second pathway for lysine degradation, the pipecolic acid pathway, is not yet fully elucidated and known enzymes are localized in the mitochondria, cytosol and peroxisome. The tissue-specific roles of these two pathways are still under investigation. The lysine degradation pathway is clinically relevant due to the occurrence of two severe neurometabolic disorders, pyridoxine-dependent epilepsy (PDE) and glutaric aciduria type 1 (GA1). The existence of three other disorders affecting lysine degradation without apparent clinical consequences opens up the possibility to find alternative therapeutic strategies for PDE and GA1 through pathway modulation. A better understanding of the mechanisms, compartmentalization and interplay between the different enzymes and metabolites involved in lysine degradation is of utmost importance.

AISF update on the diagnosis and management of adult-onset lysosomal storage diseases with hepatic involvement

Lysosomal storage diseases (LSDs) are a heterogeneous group of inherited disorders caused by loss-of-function mutations in genes encoding for lysosomal enzymes/proteins. The consequence is a progressive accumulation of substrates in these intracellular organelles, resulting in cellular and tissue damage. The overall incidence is about 1/8000 live births, but is likely underestimated. LSDs are chronic progressive multi-systemic disorders, generally presenting with visceromegaly, and involvement of the central nervous system, eyes, the skeleton, and the respiratory and cardiovascular systems. The age at onset and phenotypic expression are highly variable, according to the specific enzymatic defect and tissues involved, the residual activity, and the disease-causing genotype. Enzyme-replacement therapies and substrate-reduction therapies have recently become available, leading to the improvement in symptoms, disease progression and quality of life of affected individuals. Liver involvement and hepatosplenomegaly are frequent features of LSDs and a hallmark of adult-onset forms, frequently leading to medical attention. LSDs should therefore be considered in the differential diagnosis of liver disease with organomegaly. The present document will provide a short overview of adult-onset LSDs with hepatic involvement, highlighting the specificities and systemic manifestations of the ones most frequently encountered in clinical practice, which may hint at the correct diagnosis and the appropriate treatment.

New drugs for the treatment of Anderson-Fabry disease

Enzyme replacement therapy (ERT) of the Anderson-Fabry disease (AFD) has changed the outcome of patients. However, ERT has some limitations: a restricted volume of distribution, requirement for intravenous access, and stimulation of the production of anti-drug antibodies. Studies of new drugs aiming to improve the clinical effectiveness and convenience of therapy have been reported. Migalastat, a pharmacological chaperone, increases available enzymate activity in patients with mutations amenable to the therapy, is now available for clinical practice. It is orally administered, and while clinical trial results are promising, long term real world follow up is awaited. PEGylated enzyme has a longer half-life and potentially reduced antigenicity, compared with standard preparations; investigation of whether a longer dosing interval is viable is under way. Moss-derived enzyme has a higher affinity for mannose receptors, and appears to have access to renal tissue. Substrate reduction therapy is based on reducing the catabolism processes of the glycosphingolipids, and is currently under investigation as monotherapy. Gene therapy has now been initiated in clinical trail of in vivo and ex vivo technologies with early results are emerging. ERT represents a certain milestone of therapy for AFD with Migalastat now a newly available option. Other agents in clinical trial prevent further potential opportunities to improve outcomes in AFD.

Long-term adverse event profile from four completed trials of oral eliglustat in adults with Gaucher disease type 1

Background

Eliglustat is a first-line oral treatment for adults with Gaucher disease type 1 who have an extensive, intermediate or poor CYP2D6 metabolizer phenotype (> 90% of patients). Whereas enzyme replacement therapy for Gaucher disease has been widely used for more than two decades, eliglustat has only been in commercial use since 2014. Clinicians and patients want to better understand which adverse events are most commonly associated with eliglustat, as well as their severity, frequency, and duration.

Methods

This pooled analysis of treatment-emergent adverse events combines data from four completed eliglustat clinical trials involving 393 Gaucher disease type 1 patients. It represents 1400 patient-years of eliglustat exposure and a mean treatment duration of 3.6 years (maximum: 9.3 years).

Results

Eighty-one percent of patients remained in their respective trial until commercial availability of eliglustat (US patients only) or until trial completion. Nine patients (2.3%) withdrew from their respective trial due to one or more adverse events reported as eliglustat treatment-related; all but one of these events were mild or moderate. Overall, 97% of adverse events were mild or moderate and 86% were reported by the investigator as unrelated to eliglustat treatment. The overall rate of adverse events decreased over time and did not increase with increasing eliglustat dose. We evaluated frequency, duration, and severity of 14 adverse event terms reported at least once as treatment-related in 2% or more of all patients: dyspepsia (5.9%), headache (5.3%), abdominal pain upper (5.1%), dizziness (5.1%), diarrhea (4.6%), nausea (4.6%), arthralgia (3.6%), constipation (3.3%), abdominal pain (2.8%), gastroesophageal reflux disease (2.8%), fatigue (2.8%), palpitations (2.8%), abdominal distension (2.5%), and gastritis (2.3%). For abdominal pain upper, diarrhea, nausea, abdominal pain, and headache events, median duration was less than 14 days. All 14 adverse event terms, except for arthralgia and headache, were reported only once per patient in more than 70% of patients experiencing the event.

Conclusions

This final pooled analysis of treatment-emergent adverse events reinforces the favorable safety profile of eliglustat. The majority of the most frequently reported treatment-related adverse events were mild or moderate, transient, and occurred only once per patient.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1085-6) contains supplementary material, which is available to authorized users.

Once- versus twice-daily dosing of eliglustat in adults with Gaucher disease type 1: The Phase 3, randomized, double-blind EDGE trial

Eliglustat is a first-line oral therapy for adults with Gaucher disease type 1 (GD1) with compatible CYP2D6-metabolizer phenotypes (>90% of patients). The randomized, double-blind EDGE trial (NCT01074944, Sanofi Genzyme) evaluated once-daily eliglustat dosing compared with the approved twice-daily regimen at the same total daily dose in adults with GD1. Subjects received twice-daily dosing during a 6- to 18-month lead-in period. Only subjects who attained prespecified treatment goals for hemoglobin, platelet count, spleen and liver volumes, and bone symptoms during the lead-in period were randomized to once- or twice-daily dosing. Of 170 enrolled patients, 156 completed the lead-in period and 131 met all requirements to enter the double-blind treatment period. To achieve the composite primary endpoint in the double-blind period, patients had to maintain clinical stability relative to baseline on all five endpoints (hemoglobin, platelet count, spleen and liver volumes, and bone symptoms) and meet pharmacokinetic and other tolerability requirements as determined by the investigator after 1year of eliglustat treatment. After 1year, 80.4% (95% CI: 67.6, 89.8) of once-daily patients were stable compared with 83.1% (95% CI: 71.0, 91.6) of twice-daily patients. The 95% CI for the mean difference of -2.7% between groups was -17.7, 11.9. Because the lower bound of the CI exceeded the pre-defined non-inferiority margin of -15%, once-daily dosing could not be declared non-inferior to twice-daily dosing. Both once-daily and twice-daily patients maintained mean values for hematologic and visceral measures within established therapeutic goals during the double-blind treatment and long-term extension periods. Eliglustat was generally well-tolerated during this long-term trial (mean treatment duration: 3.3years), with just four withdrawals (2%) for related adverse events (AE), and similar AE profiles for both dosing regimens. Patients on twice-daily eliglustat showed more stability overall, and this dose regimen was better tolerated, confirming the dosing regimen for most patients specified in the drug label.

Current strategies for the treatment of inborn errors of metabolism

Inborn errors of metabolism (IEMs) are a large group of inherited disorders characterized by disruption of metabolic pathways due to deficient enzymes, cofactors, or transporters. The rapid advances in the understanding of the molecular pathophysiology of many IEMs, have led to significant progress in the development of many new treatments. The institution and continued expansion of newborn screening provide the opportunity for early treatment, leading to reduced morbidity and mortality. This review provides an overview of the diverse therapeutic approaches and recent advances in the treatment of IEMs that focus on the basic principles of reducing substrate accumulation, replacing or enhancing absent or reduced enzyme or cofactor, and supplementing product deficiency. In addition, the challenges and obstacles of current treatment modalities and future treatment perspectives are reviewed and discussed.

How close are we to therapies for Sanfilippo disease?

Sanfilippo disease is one of mucopolysaccharidoses (MPS), a group of lysosomal storage diseases characterized by accumulation of partially degraded glycosaminoglycans (GAGs). It is classified as MPS type III, though it is caused by four different genetic defects, determining subtypes A, B, C and D. In each subtype of MPS III, the primary storage GAG is heparan sulfate (HS), but mutations leading to A, B, C, and D subtypes are located in genes coding for heparan N-sulfatase (the SGSH gene), α-N-acetylglucosaminidase (the NAGLU gene), acetyl-CoA:α-glucosaminide acetyltransferase (the HGSNAT gene), and N-acetylglucosamine-6-sulfatase (the GNS gene), respectively. Neurodegenerative changes in the central nervous system (CNS) are major problems in Sanfilippo disease. They cause severe cognitive disabilities and behavioral disturbances. This is the main reason of a current lack of therapeutic options for MPS III patients, while patients from some other MPS types (I, II, IVA, and VI) can be treated with enzyme replacement therapy or bone marrow or hematopoietic stem cell transplantations. Nevertheless, although no therapy is available for Sanfilippo disease now, recent years did bring important breakthroughs in this aspect, and clinical trials are being conducted with enzyme replacement therapy, gene therapy, and substrate reduction therapy. These recent achievements are summarized and discussed in this review.

Long term substrate reduction therapy with ezetimibe alone or associated with statins in three adult patients with lysosomal acid lipase deficiency

BACKGROUND

Lysosomal acid lipase deficiency is an autosomal recessive metabolic disease with a wide range of severity from Wolman Disease to Cholesterol Ester Storage Disease. Recently enzyme replacement therapy with sebelipase alpha has been approved by drug agencies for treatment of this lysosomal disease. Ezetimibe is an azetidine derivative which blocks Niemann Pick C1-Like 1 Protein; as its consequence, plasmatic concentration of low density lipoproteins and other apoB-containing lipoproteins, that are the substrate of lysosomal acid lipase, are decreased. Furthermore, ezetimibe acts by blocking inflammasome activation which is the cause of liver fibrosis in steatohepatitis and in lysosomal storage diseases.

RESULTS

Two patients with Cholesterol Ester Storage Disease were treated with ezetimibe for 9 years and a third patients for 10 years. Treatment was supplemented with low dose of atorvastatin in the first two patients during the last 6 years. All patients showed a significant reduction of alanine aminotransferase, cholesterol and triglyceride. Furthermore, no progression of liver fibrosis was demonstrated.

CONCLUSION

In this observational case series, ezetimibe is effective, safe, and sustainable treatment for lysosomal acid lipase deficiency. Further studies are warranted to demonstrate that ezetimibe is an alternative therapy to enzyme replacement therapy.

Combined miglustat and enzyme replacement therapy in two patients with type 1 Gaucher disease: two case reports

BACKGROUND

Intravenous enzyme replacement therapy is a first-line therapy for Gaucher disease type 1, and substrate reduction therapy represents an oral treatment alternative. Both enzyme replacement therapy and substrate reduction therapy are generally used as monotherapies in Gaucher disease. However, one randomized study and several case reports have described combination therapy over short time periods.

CASE PRESENTATION

We report two female Gaucher disease type 1 patients of mainly Anglo-Saxon descent, where combined enzyme replacement therapy and miglustat substrate reduction therapy were administered to overcome refractory clinical symptoms. The first patient was diagnosed at age 17 and developed Gaucher disease-related bone manifestations that worsened despite starting imiglucerase enzyme replacement therapy. After switching to miglustat substrate reduction therapy, her bone symptoms improved, but she developed tremors and eventually switched back to enzyme replacement therapy. Miglustat was later recommenced in combination with ongoing enzyme replacement therapy due to continued bone pain, and her bone symptoms improved along with maintained visceral manifestations. Enzyme replacement therapy was subsequently tapered off and the patient has since been successfully maintained on miglustat. The second patient was diagnosed aged 3, and commenced imiglucerase enzyme replacement therapy aged 15. After 9 years on enzyme replacement therapy she switched to miglustat substrate reduction therapy and her core symptoms were maintained/stable for 3 years. Imiglucerase enzyme replacement therapy was later added as a boost to therapy and her symptoms were subsequently maintained over a 2.3-year period. However, miglustat was discontinued due to her relocation, necessitating an increase in enzyme replacement therapy dose. Overall, both patients benefited from combination therapy.

CONCLUSION

While the majority of Gaucher disease type 1 patients will not need treatment with both substrate reduction therapy and enzyme replacement therapy, the current case reports demonstrate that judicious use of combination therapy may be of benefit in some cases.

Current and Future Treatments for Lysosomal Storage Disorders

Purpose of review Lysosomal storage disorders (LSDs) are a class of genetic disorders that are a testing ground for the invention of novel therapeutics including enzyme replacement therapy (ERT), substrate reduction therapy (SRT), gene therapy, and hematopoietic stem cell transplant (HSCT). This review summarizes recently approved drugs, then examines the successful clinical trials in gene therapy and HSCT. Recent findings The FDA has recently approved a second SRT by reversing an earlier FDA decision, suggesting a favorable regulatory landscape going forward. Adeno-associated virus therapies, adenovirus therapies, and HSCT have overcome limitations of earlier clinical and preclinical trials, suggesting that gene therapy may be a reality for LSDs in the near future. At the same time, the first EU-approved gene therapy drug, Glybera, has been discontinued, and other ex vivo-based therapies although approved for clinical use have failed to be widely adapted and are no longer economically viable. Summary There are now 11 ERTs and two SRTs approved for LSDs in the USA. Gene therapy approaches and HSCT have also demonstrated promising clinical trial results suggesting that these therapies are on the frontier. Challenges that remain include navigating immune responses, developing drugs capable of crossing the blood-brain barrier (BBB), developing therapies that can reverse end-organ damage, and achieving these goals in a safe, ethical, and financially sustainable manner. The amount of active development and a track record of iterative progress suggest that treatments for LSDs will continue to be a field of innovation, problem solving, and success.

The treatment of juvenile/adult GM1-gangliosidosis with Miglustat may reverse disease progression

Juvenile and adult GM1-gangliosidosis are invariably characterized by progressive neurological deterioration. To date only symptomatic therapies are available. We report for the first time the positive results of Miglustat (OGT 918, N-butyl-deoxynojirimycin) treatment on three Italian GM1-gangliosidosis patients. The first two patients had a juvenile form (enzyme activity ≤5%, GLB1 genotype p.R201H/c.1068 + 1G > T; p.R201H/p.I51N), while the third patient had an adult form (enzyme activity about 7%, p.T329A/p.R442Q). Treatment with Miglustat at the dose of 600 mg/day was started at the age of 10, 17 and 28 years; age at last evaluation was 21, 20 and 38 respectively. Response to treatment was evaluated using neurological examinations in all three patients every 4-6 months, the assessment of Movement Disorder-Childhood Rating Scale (MD-CRS) in the second patient, and the 6-Minute Walking Test (6-MWT) in the third patient. The baseline neurological status was severely impaired, with loss of autonomous ambulation and speech in the first two patients, and gait and language difficulties in the third patient. All three patients showed gradual improvement while being treated; both juvenile patients regained the ability to walk without assistance for few meters, and increased alertness and vocalization. The MD-CRS class score in the second patient decreased from 4 to 2. The third patient improved in movement and speech control, the distance covered during the 6-MWT increased from 338 to 475 m. These results suggest that Miglustat may help slow down or reverse the disease progression in juvenile/adult GM1-gangliosidosis.

Attitudes of Individuals with Gaucher Disease toward Substrate Reduction Therapies

Type 1 Gaucher disease (GD) is the most common lysosomal storage disorder. Previously, treatment for GD was limited to intravenous enzyme replacement therapies (ERTs). More recently, oral substrate reduction therapies (SRTs) were approved for treatment of GD. Although both therapies alleviate disease symptoms, attitudes toward SRTs and patient perceptions of health while using SRT have not been well established. Electronic surveys were administered to adults with GD and asked about treatment history, attitudes toward SRTs, and perception of health while using SRTs as compared to ERTs, if applicable to the participant. ERT users that were offered treatment with SRTs cited potential side effects, wanting more research on SRTs, and satisfaction with their current treatment regimen as reasons for declining SRTs. SRT users expressed convenience and less invasiveness as reasons for choosing SRTs. Additionally, those using SRTs most often perceived their health to be similar to when they previously used ERT. Participant responses illustrate that attitudes toward SRTs can be variable and that one particular treatment may not be ideal for all patients with GD depending on individual perceptions of factors such as convenience, invasiveness, or side effects. Thus, individuals with GD should be counseled adequately by healthcare providers about both ERTs and SRTs for treatment of GD now that SRTs are clinically available.

Treatment of profound thrombocytopenia in a patient with Gaucher disease type 1: Is there a role for substrate reduction therapy

The availability of three enzyme replacement therapy (ERT) drugs and two substrate reduction therapy (SRT) drugs to treat Gaucher disease provides an opportunity to tailor therapies to a patient's specific clinical concerns. However, there is a gap in the literature regarding individual drug effectiveness in treating particular symptoms and the potential benefits of combination treatment.

This report details treatment of a patient with Gaucher disease type 1 whose main clinical concern was profound thrombocytopenia (around 20 × 10⁹/L, normal range: 150–450 × 10⁹/L) with several episodes of bleeding with minimal trauma and bruises. The patient was treated with ERT at doses up to 60 units/kg weekly, with no improvement in platelet levels for 6 years. Subsequently, the patient transitioned to SRT and platelet levels increased almost two fold within the first month, and have remained stable at safe levels (30–60 × 10⁹/L) for almost 2.5 years at the time of publication.

This report demonstrates a possible therapeutic benefit of SRT in individual patients who do not meet therapeutic goals in terms of thrombocytopenia after a considerable period on first-line ERT treatment. Oral administration of SRT also improved this patient's quality of life allowing discontinuation of weekly ERT infusions, which better accommodated her demanding career and busy lifestyle.

The metabolism of glucocerebrosides - From 1965 to the present

Gaucher disease is caused by the defective catabolism of the simple glycosphingolipid, glucosylceramide (GlcCer), due to mutations in the GBA1 gene which encodes for acid β-glucosidase (GCase), the lysosomal enzyme that degrades GlcCer. Today, Gaucher disease patients are routinely treated with recombinant GCase, in a treatment regimen known as enzyme replacement therapy (ERT). We now review the biochemical basis of ERT and discuss how this treatment has advanced since it was first pioneered by Dr. Roscoe Brady in the 1960s. We will place particular emphasis on the three dimensional structure of GCase, and subsequently discuss a relatively new treatment paradigm, substrate reduction therapy (SRT), in which GlcCer synthesis is partially inhibited, thus reducing its accumulation. Both of these approaches are based on studies and concepts developed by Dr. Brady over his remarkable research career spanning six decades.

Management and monitoring recommendations for the use of eliglustat in adults with type 1 Gaucher disease in Europe

PURPOSE

In Gaucher disease, diminished activity of the lysosomal enzyme, acid β-glucosidase, leads to accumulation of glucosylceramides and related substrates, primarily in the spleen, liver, and bone marrow. Eliglustat is an oral substrate reduction therapy approved in the European Union and the United States as a first-line treatment for adults with type 1 Gaucher disease who have compatible CYP2D6 metabolism phenotypes. A European Advisory Council of experts in Gaucher disease describes the characteristics of eliglustat that are distinct from enzyme augmentation therapy (the standard of care) and miglustat (the other approved substrate reduction therapy) and recommends investigations and monitoring for patients on eliglustat therapy within the context of current recommendations for Gaucher disease management.

RESULTS

Eliglustat is a selective, potent inhibitor of glucosylceramide synthase, the enzyme responsible for biosynthesis of glucosylceramides which accumulate in Gaucher disease. Extensive metabolism of eliglustat by CYP2D6, and, to a lesser extent, CYP3A of the cytochrome P450 pathway, necessitates careful consideration of the patient's CYP2D6 metaboliser status and use of concomitant medications which share metabolism by these pathways. Guidance on specific assessments and monitoring required for eliglustat therapy, including an algorithm to determine eligibility for eliglustat, are provided.

CONCLUSIONS

As a first-line therapy for type 1 Gaucher disease, eliglustat offers eligible patients a daily oral therapy alternative to biweekly infusions of enzyme therapy. Physicians will need to carefully assess individual Gaucher patients to determine their appropriateness for eliglustat therapy. The therapeutic response to eliglustat and use of concomitant medications will require long-term monitoring.

Successful switch from enzyme replacement therapy to miglustat in an adult patient with type 1 Gaucher disease: a case report

Background

Gaucher disease is one of the most common lipid-storage disorders, affecting approximately 1 in 75,000 births. Enzyme replacement therapy with recombinant glucocerebrosidase is currently considered the first-line treatment choice for patients with symptomatic Gaucher disease type 1. Oral substrate reduction therapy is generally considered a second-line treatment option for adult patients with mild to moderate Gaucher disease type 1 who are unable or unwilling to receive lifelong intravenous enzyme infusions. The efficacy and safety of the oral substrate reduction therapy miglustat (Zavesca®) in patients with Gaucher disease type 1 have been established in both short-term clinical trials and long-term, open-label extension studies. Published data indicate that miglustat can be used as maintenance therapy in patients with stable Gaucher disease type 1 switched from previous enzyme replacement therapy.

Case presentation

We report a case of a 44-year-old Caucasian man with Gaucher disease type 1 who was initially treated with enzyme replacement therapy but, owing to repeated cutaneous allergic reactions, had to be switched to miglustat after several attempts with enzyme replacement therapy. Despite many attempts, desensitization treatment did not result in improved toleration of imiglucerase infusions, and the patient became unwilling to continue with any intravenous enzyme replacement therapy. He subsequently agreed to switch to oral substrate reduction therapy with miglustat 100 mg twice daily titrated up to 100 mg three times daily over a short period. Long-term miglustat treatment maintained both hemoglobin and platelet levels within acceptable ranges over 8 years. The patient’s spleen volume decreased, his plasma chitotriosidase levels stayed at reduced levels, and his bone mineral density findings have remained stable throughout follow-up. The patient’s quality of life has remained satisfactory. Miglustat showed good gastrointestinal tolerability in this patient, and no adverse events have been reported.

Conclusions

Oral miglustat therapy proved to be a valid alternative treatment to intravenous enzyme replacement therapy for long-term maintenance in this patient with Gaucher disease type 1, who showed persistent allergic intolerance to imiglucerase infusions. This report exemplifies the type of patient with Gaucher disease type 1 who can benefit from switching from enzyme replacement therapy to substrate reduction therapy.

Treatment patterns from 647 patients with Gaucher disease: An analysis from the Gaucher Outcome Survey

The Gaucher Outcome Survey (GOS) is an international disease-specific registry established in 2010 for patients with a confirmed diagnosis of Gaucher disease (GD), regardless of GD type or treatment status. For insight into how GD management varies among countries, we analyzed treatment patterns in GOS. As of October 30, 2015, data on GD-specific treatment (enzyme replacement therapy, substrate reduction therapy, or chemical chaperone therapy) received at any time were available for 647 patients. At analysis, velaglucerase alfa (316/573, 55.1%) and imiglucerase (184/573, 32.1%) were the treatments most widely used. Of the 647 treated patients, 446 (68.9%) had been treated for >5years and 368 (56.9%) had received only one GD-specific drug therapy. There were 377 patients who received velaglucerase alfa. Velaglucerase alfa was most widely used at 60U/kg every other week (134/492 dose entries, 27.2%), but there were differences in dosing between the three highest-enrolling countries (defined as >100 GOS patients enrolled in each), with most patients in Israel receiving <20U/kg, most patients in the United Kingdom receiving 20 to <40U/kg, and most in the United States receiving 60U/kg. This analysis provides a foundation upon which to examine real-life outcomes data from different treatment regimens globally.

Clinical response to eliglustat in treatment-naïve patients with Gaucher disease type 1: Post-hoc comparison to imiglucerase-treated patients enrolled in the International Collaborative Gaucher Group Gaucher Registry

Eliglustat is a recently approved oral therapy in the United States and Europe for adults with Gaucher disease type 1 who are CYP2D6 extensive, intermediate, or poor metabolizers (> 90% of patients) that has been shown to decrease spleen and liver volume and increase hemoglobin concentrations and platelet counts in untreated adults with Gaucher disease type 1 and maintain these parameters in patients previously stabilized on enzyme replacement therapy. In a post-hoc analysis, we compared the results of eliglustat treatment in treatment-naïve patients in two clinical studies with the results of imiglucerase treatment among a cohort of treatment-naïve patients with comparable baseline hematologic and visceral parameters in the International Collaborative Gaucher Group Gaucher Registry. Organ volumes and hematologic parameters improved from baseline in both treatment groups, with a time course and degree of improvement in eliglustat-treated patients similar to imiglucerase-treated patients.

Normalisation of brain spectroscopy findings in Niemann-Pick disease type C patients treated with miglustat

Niemann-Pick disease type C (NP-C) is a fatal progressive neurolipidosis involving neuronal storage of cholesterol and gangliosides. Miglustat, an inhibitor of glycosphingolipid synthesis, has been approved to treat neurological manifestations in adults and children with NP-C. This open-label observational study in adults with confirmed NP-C evaluated the efficacy of miglustat (200 mg t.i.d.) based on composite functional disability (CFD) scores and brain proton magnetic resonance spectroscopy (H-MRS) measurement of choline (Cho)/N-acetyl aspartate (NAA) ratio in the centrum ovale. Overall, 16 patients were included and received miglustat for a mean period of 30.6 months: 12 continued on miglustat throughout follow up, and 4 discontinued miglustat because of adverse effects (n = 2) or perceived lack of efficacy (n = 2). In the 'continued' subgroup, the mean (SD) annual progression of CFD scores decreased from 0.75 (0.94) before treatment to 0.29 (1.29) during the period between miglustat initiation and last follow-up. In the discontinued subgroup, CFD progression increased from 0.48 (0.44) pre-treatment to 1.49 (1.31) at last follow up (off treatment). Mean (SD) Cho/NAA ratio [normal level 0.48 (0.076)] decreased during miglustat treatment in the continued subgroup: 0.64 (0.12) at baseline (miglustat initiation), 0.59 (0.17) at 12-month follow up, and 0.48 (0.09) at 24-month follow up. Cho/NAA ratio remained relatively stable in the discontinued subgroup: 0.57 (0.15), 0.53 (0.04) and 0.55 (0.09), respectively. In conclusion, H-MRS Cho/NAA ratio might serve as an objective, quantitative neurological marker of brain dysfunction in NP-C, allowing longitudinal analysis of the therapeutic effect of miglustat.

Recommendations for the use of eliglustat in the treatment of adults with Gaucher disease type 1 in the United States

In Gaucher disease, deficient activity of acid β-glucosidase results in accumulation of its substrates, glucosylceramide and glucosylsphingosine, within the lysosomes of cells primarily in the spleen, liver, bone marrow, and occasionally the lung. The multisystem disease is predominantly characterized by hepatosplenomegaly, anemia, thrombocytopenia, and skeletal disease. Enzyme replacement therapy with recombinant human acid β-glucosidase has been the first-line therapy for Gaucher disease type 1 for more than two decades. Eliglustat, a novel oral substrate reduction therapy, was recently approved in the United States and the European Union as a first-line treatment for adults with Gaucher disease type 1. Eliglustat inhibits glucosylceramide synthase, thereby decreasing production of the substrate glucosylceramide and reducing its accumulation. Although existing recommendations for the care of patients with Gaucher disease remain in effect, unique characteristics of eliglustat require additional investigation and monitoring. A panel of physicians with expertise in Gaucher disease and experience with eliglustat in the clinical trials provide guidance regarding the use of eliglustat, including considerations before starting therapy and monitoring of patients on eliglustat therapy.

Neurological and cardiac responses after treatment with miglustat and a ketogenic diet in a patient with Sandhoff disease

Sandhoff disease is a progressive neurodegenerative disorder characterized by accumulation of GM2 gangliosides. We describe a 6-year-old male with coarse facial features, developmental delay, refractory seizures, hypertrophic cardiomyopathy, who was later found to have Sandhoff disease. Previous studies have revealed that caloric restriction in combination with miglustat increased survival and motor behavior in mouse model of Sandhoff disease. These findings suggest that combination therapy may result in improved outcomes for patients with Sandhoff. Initiation of treatment with miglustat and a ketogenic diet was followed by improvement of the patient's seizure control and cardiac function. Further clinical investigation is required to better determine the benefit of management in late-onset forms of Sandhoff disease.