Understanding and modifying Fabry disease: Rationale and design of a pivotal Phase 3 study and results from a patient-reported outcome validation study

Pompe disease: Unmet needs and emerging therapies

Pompe disease is a debilitating and life-threatening disease caused by aberrant accumulation of glycogen resulting from reduced acid alpha-glucosidase activity. The first treatment for Pompe disease, the enzyme replacement therapy, Myozyme® (recombinant human acid alpha-glucosidase, alglucosidase alfa), is a lifesaving treatment for the most severe form of the disease and provided clinically meaningful benefits to patients with milder phenotypes. Nonetheless, many patients display suboptimal responses or clinical decline following years of alglucosidase alfa treatment. The approval of avalglucosidase alfa (Nexviazyme®) and cipaglucosidase alfa (Pombiliti®) with miglustat (Opfolda®) represents a new generation of enzyme replacement therapies seeking to further improve patient outcomes beyond alglucosidase alfa. However, the emergence of a complicated new phenotype with central nervous system involvement following long-term treatment, coupled with known and anticipated unmet needs of patients receiving enzyme replacement therapy, has prompted development of innovative new treatments. This review provides an overview of the challenges of existing treatments and a summary of emerging therapies currently in preclinical or clinical development for Pompe disease and related lysosomal storage disorders. Key treatments include tissue-targeted enzyme replacement therapy, which seeks to enhance enzyme concentration in target tissues such as the central nervous system; substrate reduction therapy, which reduces intracellular glycogen concentrations via novel mechanisms; and gene therapy, which may restore endogenous production of deficient acid alpha-glucosidase. Each of these proposed treatments shows promise as a future therapeutic option to improve quality of life in Pompe disease by more efficiently treating the underlying cause of disease progression: glycogen accumulation.

Systematic Review of Genetic Substrate Reduction Therapy in Lysosomal Storage Diseases: Opportunities, Challenges and Delivery Systems

BACKGROUND

Genetic substrate reduction therapy (gSRT), which involves the use of nucleic acids to downregulate the genes involved in the biosynthesis of storage substances, has been investigated in the treatment of lysosomal storage diseases (LSDs).

OBJECTIVE

To analyze the application of gSRT to the treatment of LSDs, identifying the silencing tools and delivery systems used, and the main challenges for its development and clinical translation, highlighting the contribution of nanotechnology to overcome them.

METHODS

A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines was performed. PubMed, Scopus, and Web of Science databases were used for searching terms related to LSDs and gene-silencing strategies and tools.

RESULTS

Fabry, Gaucher, and Pompe diseases and mucopolysaccharidoses I and III are the only LSDs for which gSRT has been studied, siRNA and lipid nanoparticles being the silencing strategy and the delivery system most frequently employed, respectively. Only in one recently published study was CRISPR/Cas9 applied to treat Fabry disease. Specific tissue targeting, availability of relevant cell and animal LSD models, and the rare disease condition are the main challenges with gSRT for the treatment of these diseases. Out of the 11 studies identified, only two gSRT studies were evaluated in animal models.

CONCLUSIONS

Nucleic acid therapies are expanding the clinical tools and therapies currently available for LSDs. Recent advances in CRISPR/Cas9 technology and the growing impact of nanotechnology are expected to boost the clinical translation of gSRT in the near future, and not only for LSDs.

[What is confirmed in the treatment of Fabry's disease?]

Fabry's disease is a rare X chromosome-linked inherited lysosomal storage disease characterized by insufficient metabolism of the substrate globotriaosylceramide (Gb3) due to reduced alpha-galactosidase A (AGAL) activity. Lysosomal Gb3 accumulation causes a multisystemic disease which, if untreated, reduces the life expectancy in females and males by around 10 and 20 years, respectively, due to progressive renal dysfunction, hypertrophic cardiomyopathy, cardiac arrhythmia and early occurrence of cerebral infarction. The diagnosis is confirmed by determining the reduced AGAL activity in leukocytes in males and molecular genetic detection of a -mutation causing the disease in females. The treatment comprises enzyme replacement therapy (ERT), agalsidase alfa, 0.2 mg/kg body weight (BW), agalsidase beta 1.0 mg/kg BW or pegunigalsidase alfa 1.0 mg/kg BW every 2 weeks i.v. or oral chaperone therapy (one capsule of migalastat 123 mg every other day) in the presence of amenable mutations. This article summarizes the data on the treatment of Fabry's disease and on complications in practice. The current guideline recommendations are addressed and new study results that could expand the therapeutic repertoire in the future are discussed.

Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Oral AL01211 in Healthy Chinese Volunteers

BACKGROUND AND OBJECTIVE

Aberrant accumulation of glycosphingolipids (GSLs) in the lysosome leads to GSL storage diseases. Glucosylceramide synthase inhibitors (GCSi) have the potential to treat several GSL storage diseases by reducing the synthesis of the disease-causing GSLs. AL01211 is a potent oral GCSi under investigation for Type 1 Gaucher disease and Fabry disease. Here, we evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of AL01211 in healthy Chinese volunteers.

METHODS

AL01211 was tested in a Phase 1, single-center, randomized, double-blind, placebo-controlled study with single-dose (15 and 60 mg) and multiple-dose (30 mg) arms.

RESULTS

Results of AL01211 demonstrated dose-dependent pharmacokinetics, rapid absorption (median time to maximum plasma concentration [tmax] 2.5-4 hours), relatively slow clearance rate (mean apparent total clearance from plasma [CL/F] 88.3-200 L/h) and the mean terminal half-life above 30 hours. Repeated once-daily oral administration of AL01211 for 14 days had an approximately 2-fold accumulation, reaching steady-state levels between 7 and 10 days, and led to a 73% reduction in plasma glucosylceramide (GL1) on Day 14. AL01211 was safe and well tolerated, with no identified serious adverse events.

CONCLUSION

AL01211 showed a favorable pharmacokinetic, pharmacodynamics, safety, and tolerability profile in healthy Chinese volunteers. These data support the further clinical development of AL01211 as a therapy for GSL storage diseases.

CLINICAL TRIAL REGISTRY

Clinical Trial Registry no. CTR20221202 ( http://www.chinadrugtrials.org.cn ) registered on 6 June 2022 and ChiCTR2200061431 ( http://www.chictr.org.cn ) registered on 24 June 2022.

A systematic literature review on the health-related quality of life and economic burden of Fabry disease

BACKGROUND

Fabry disease (FD) is a rare lysosomal storage disease associated with glycolipid accumulation that impacts multiple physiological systems. We conducted a systematic literature review (SLR) to characterize the humanistic (quality of life [QoL]) and economic burden of FD.

METHODS

Searches were conducted in the Embase, MEDLINE®, and MEDLINE® In-Process databases from inception to January 19, 2022. Conference abstracts of specified congresses were manually searched. Additional searches were performed in the Cochrane and ProQuest databases for the humanistic SLR and the National Health Service Economic Evaluations Database for the economic SLR. Studies of patients with FD of any sex, race, and age, and published in the English language were included. There was no restriction on intervention or comparator. For the humanistic SLR, studies that reported utility data, database/registry-based studies, questionnaires/surveys, and cohort studies were included. For the economic SLR, studies reporting economic evaluations or assessing the cost of illness and resource use were included.

RESULTS

Of the 1363 records identified in the humanistic search, 36 studies were included. The most commonly used QoL assessments were the 36-item Short-Form Health Survey (n = 16), EQ-5D questionnaire descriptive system or visual analog scale (n = 9), and the Brief Pain Inventory (n = 8). Reduced QoL was reported in patients with FD compared with healthy populations across multiple domains, including pain, physical functioning, and depressive symptoms. Multiple variables-including sex, age, disease severity, and treatment status-impacted QoL. Of the 711 records identified in the economic burden search, 18 studies were included. FD was associated with high cost and healthcare resource use. Contributors to the cost burden included enzyme replacement therapy, healthcare, and social care. In the seven studies that reported health utility values, lower utility scores were generally associated with more complications (including cardiac, renal, and cerebrovascular morbidities) and with classical disease in males.

CONCLUSION

FD remains associated with a high cost and healthcare resource use burden, and reduced QoL compared with healthy populations. Integrating information from QoL and economic assessments may help to identify interventions that are likely to be of most value to patients with FD.

Outcomes and management of kidney transplant recipients with Fabry disease: a review

Fabry disease is an X-linked inheritable lysosomal storage disease caused by various mutations of the galactosidase α gene resulting in α-galactosidase deficiency. Chronic kidney disease (CKD) is one of the most significant consequences of Fabry disease, with risk of end-stage kidney disease (ESKD) in this population. Like for other patients with ESKD, kidney transplant is the optimal treatment for Fabry disease patients with ESKD. However, enzyme replacement therapy and newer Fabry disease treatments remain important to mitigate other end organ damage such as cardiomyopathy post transplantation. This review is a primer on Fabry disease, which examines the outcomes of disease in the context of kidney transplant prior to, and during, the enzyme replacement treatment era, medical treatment of kidney transplant recipients with Fabry disease, and progress in screening studies.

Hypertrophic Cardiomyopathy versus Storage Diseases with Myocardial Involvement

One of the main causes of heart failure is cardiomyopathies. Among them, the most common is hypertrophic cardiomyopathy (HCM), characterized by thickening of the left ventricular muscle. This article focuses on HCM and other cardiomyopathies with myocardial hypertrophy, including Fabry disease, Pompe disease, and Danon disease. The genetics and pathogenesis of these diseases are described, as well as current and experimental treatment options, such as pharmacological intervention and the potential of gene therapies. Although genetic approaches are promising and have the potential to become the best treatments for these diseases, further research is needed to evaluate their efficacy and safety. This article describes current knowledge and advances in the treatment of the aforementioned cardiomyopathies.

Cardiovascular Involvement in Fabry's Disease: New Advances in Diagnostic Strategies, Outcome Prediction and Management

Cardiovascular involvement is common in Fabry's disease and is the leading cause of morbidity and mortality. The research is focused on identifying diagnostic clues suggestive of cardiovascular involvement in the preclinical stage of the disease through clinical and imaging markers. Different pathophysiologically driven therapies are currently or will soon be available for the treatment of Fabry's disease, with the most significant benefit observed in the early stages of the disease. Thus, early diagnosis and risk stratification for adverse outcomes are crucial to determine when to start an aetiological treatment. This review describes the cardiovascular involvement in Fabry's disease, focusing on the advances in diagnostic strategies, outcome prediction and disease management.

Novel Golden Lipid Nanoparticles with Small Interference Ribonucleic Acid for Substrate Reduction Therapy in Fabry Disease

Substrate reduction therapy (SRT) has been proposed as a new gene therapy for Fabry disease (FD) to prevent the formation of globotriaosylceramide (Gb3). Nanomedicines containing different siRNA targeted to Gb3 synthase (Gb3S) were designed. Formulation factors, such as the composition, solid lipid nanoparticles (SLNs) preparation method and the incorporation of different ligands, such as gold nanoparticles (GNs), protamine (P) and polysaccharides, were evaluated. The new siRNA-golden LNPs were efficiently internalized in an FD cell model (IMFE-1), with GNs detected in the cytoplasm and in the nucleus. Silencing efficacy (measured by RT-qPCR) depended on the final composition and method of preparation, with silencing rates up to 90% (expressed as the reduction in Gb3S-mRNA). GNs conferred a higher system efficacy and stability without compromising cell viability and hemocompatibility. Immunocytochemistry assays confirmed Gb3S silencing for at least 15 days with the most effective formulations. Overall, these results highlight the potential of the new siRNA-golden LNP system as a promising nanomedicine to address FD by specific SRT.