Population Pharmacokinetics of Oral Migalastat in Adolescents and Adults With and Without Renal Impairment

Migalastat is approved for the treatment of Fabry disease (FD) with amenable variants. Objectives were to characterize effects of estimated glomerular filtration rate (eGFR) on oral clearance (CL), predict doses in mild to moderate renal impairment and in pediatric patients with FD, and to improve designs of FD studies. A 2-compartment model was fit to data from 260 subjects with/without FD and iteratively refined with evolving data. FD, eGFR, and weight affected CL, while weight and FD affected volume. Optimal sampling theory was used to choose pharmacokinetic sampling times for pediatric studies. Doses in patients with renal impairment and in pediatrics were determined by targeting exposure in adults receiving migalastat 123 mg every other day. A clinical study was conducted in 20 adolescent patients with FD ≥45 kg. eGFR had the largest effect on CL. Simulations showed that exposures in moderate renal impairment were within phase 2-3 exposures; patients aged 2-17 years require weight-based dosing; and predicted exposures in adolescent patients ≥45 kg receiving migalastat 123 mg every other day were similar to adults (data confirmed in a clinical study). Model-informed drug development optimized dosing and design of clinical studies and supported that no dose adjustments were needed in patients with mild to moderate renal impairment or in adolescent patients ≥45 kg.

[Chaperone molecules: The example of Fabry disease]

Fabry disease is due to mutations in the GLA gene that cause a deficiency of the activity of the lysosomal enzyme alpha-galactosidase A (α-gal A) resulting in intra-tissue accumulation of globotriaosylceramide. Recently, a novel therapeutic approach based on the pharmacological chaperone migalastat has been developed. It binds, in a specific and reversible manner, to the catalytic site of α-gal A mutants, to prevent their degradation by the quality control system of the endoplasmic reticulum and allow them to catabolize globotriaosylceramide in the lysosomes. This treatment concerns approximately 35% of the GLA gene mutations recognized as sensitive to migalastat according to an in vitro pharmacogenetic test. Two pivotal Phase III studies, FACETS: migalastat vs. placebo and ATTRACT: migalastat vs. enzyme replacement therapy analyzed the in vivo effects of migalastat. Despite some methodological limitations, promising results were found. Migalastat seems to be more effective than enzyme replacement therapy in reducing left ventricular mass index in case of cardiac hypertrophy and has comparable renal effects. This oral treatment is the first personalized treatment, based on the genetic profile of Fabry patients and opens a new era in the management of conformational diseases.

Migalastat Tissue Distribution: Extrapolation From Mice to Humans Using Pharmacokinetic Modeling and Comparison With Agalsidase Beta Tissue Distribution in Mice

Approved therapies for Fabry disease (FD) include migalastat, an oral pharmacological chaperone, and agalsidase beta and agalsidase alfa, 2 forms of enzyme replacement therapy. Broad tissue distribution may be beneficial for clinical efficacy in FD, which has severe manifestations in multiple organs. Here, migalastat and agalsidase beta biodistribution were assessed in mice and modeled using physiologically based pharmacokinetic (PBPK) analysis, and migalastat biodistribution was subsequently extrapolated to humans. In mice, migalastat concentration was highest in kidneys and the small intestine, 2 FD-relevant organs. Agalsidase beta was predominantly sequestered in the liver and spleen (organs unaffected in FD). PBPK modeling predicted that migalastat 123 mg every other day resulted in concentrations exceeding the in vitro half-maximal effective concentration in kidneys, small intestine, skin, heart, and liver in human subjects. However, extrapolation of mouse agalsidase beta concentrations to humans was unsuccessful. In conclusion, migalastat may distribute to tissues that are inaccessible to intravenous agalsidase beta in mice, and extrapolation of mouse migalastat concentrations to humans showed adequate tissue penetration, particularly in FD-relevant organs.

1-Deoxynojirimycin and its Derivatives: A Mini Review of the Literature

1-Deoxynojirimycin (1-DNJ) is a naturally occurring sugar analogue with unique bioactivities. It is found in mulberry leaves and silkworms, as well as in the metabolites of certain microorganisms, including Streptomyces and Bacillus. 1-DNJ is a potent α-glucosidase inhibitor and it possesses anti-hyperglycemic, anti-obese, anti-viral and anti-tumor properties. Some derivatives of 1-DNJ, like miglitol, miglustat and migalastat, were applied clinically to treat diseases such as diabetes and lysosomal storage disorders. The present review focused on the extraction, determination, pharmacokinetics and bioactivity of 1-DNJ, as well as the clinical application of 1-DNJ derivatives.

Migalastat: A Review in Fabry Disease

Fabry disease is a rare lysosomal disorder characterized by deficient or absent α-galactosidase A activity resulting from mutations in the GLA gene. Migalastat (Galafold™), a pharmacological chaperone, stabilizes and facilitates trafficking of amenable mutant forms of α-galactosidase A enzyme from the endoplasmic reticulum to lysosomes and increases its lysosomal activity. Oral migalastat is the first pharmacological chaperone approved for treating patients [aged ≥ 18 years (USA and Canada) or ≥ 16 years in other countries] with Fabry disease who have a migalastat-amenable GLA mutation. In the FACETS trial in enzyme replacement therapy (ERT)-naive patients with GLA mutations amenable or non-amenable to migalastat, there was no significant difference between the migalastat and placebo groups for the proportion of patients achieving a ≥ 50% reduction in the number of globotriaosylceramide (GL-3) inclusions/kidney interstitial capillary (KIC) at 6 months [primary endpoint; intent-to-treat (ITT) population]. In the modified ITT population (i.e. patients with migalastat-amenable GLA mutations), relative to placebo, migalastat treatment significantly reduced the mean number of GL-3 inclusions/KIC and plasma lyso-globotriaosylsphingosine levels at 6 months. Among evaluable patients, migalastat maintained renal function and reduced cardiac mass after ≤ 24 months’ therapy. In the ATTRACT trial in ERT-experienced patients, renal function was maintained during 18 months of migalastat or ERT; however, migalastat significantly reduced cardiac mass compared with ERT. Migalastat was generally well tolerated in both of these trials. Given its convenient oral regimen and the limited therapeutic options available, migalastat is an important treatment option for Fabry disease in patients with migalastat-amenable GLA mutations.

Systematic review of oral and craniofacial findings in patients with Fabry disease or Pompe disease

Fabry disease and Pompe disease are rare lysosomal storage disorders that belong to a heterogeneous group of more than 200 distinct inborn metabolic diseases. Mutations followed by loss of function of enzymes or transporters that are localised in the acidic environment of the lysosome may result in degradation of many substrates, such as glycosaminoglycans, glycosphingolipids, glycogen, cholesterol, oligosaccharides, glycoproteins, and peptides, or the excretion of the products degraded by the lysosome. Our aim was to identify the oral signs and symptoms of Fabry disease and Pompe disease from a systematic review made using MEDLINE/PubMed, and a hand search for relevant articles, following the PRISMA guidelines. Both diseases show various craniofacial and oral changes, including supernumerary teeth, dental agenesis, angiokeratoma, and telangiectases in Fabry disease; and macroglossia, teeth fusion, and taurodontism in Pompe disease. Common clinical signs of Fabry disease include hyposalivation, hypohidrosis, and xerophthalmia, and a generally reduced physical resilience was apparent in patients with Pompe disease. Oral and craniofacial changes in patients with both diseases extend over their entire lifetime and can be detected even in an infant. Lysosomal storage diseases should be taken into consideration in the differential diagnosis of relevant diverse symptoms, because treatment, when available, is most effective when started early. The main therapeutic concepts are enzymatic replacement for Pompe disease, whereas patients with Fabry disease require additional oral chaperone treatment or enzyme replacement.

Treatment in Fabry disease

Fabry disease is an X-linked inborn disease caused by deficit of alpha-galactosidaseA. This results in accumulation of glycosphingolipids in all cells and tissues. All males should receive enzyme replacement treatment in case of very low or undetectable levels of alpha-galactosidaseA. Female carriers and males with marginally levels of alpha-galactosidaseA should be treated in case of renal, neurologic o cardiac manifestations. There are two intravenous formulations of human recombinant enzyme, agalsidase alpha and agalsidase beta, showing similar efficacy and safety. Patients with amenable mutations of alpha-galactosidase can be treated with oral migalastat hydrochloride. Migalastat hydrochloride is a pharmacological chaperone that facilitates trafficking of alpha-galactosidaseA to lysosomes increasing enzyme activity. Patients treated with migalastat hydrochloride had significant improvements in left ventricular mass and gastrointestinal symptoms.

Fabry Nephropathy: An Evidence-Based Narrative Review

Fabry disease (FD) is a rare, X-linked disorder caused by mutations in the GLA gene encoding the enzyme α-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb3) and other glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb3 in podocytes, endothelial cells, epithelial cells, and tubular cells contribute to the renal symptoms of FD, which manifest as proteinuria and reduced glomerular filtration rate leading to renal insufficiency. A correct diagnosis of FD, although challenging, has considerable implications regarding treatment, management, and counseling. The diagnosis may be confirmed by demonstrating the enzyme deficiency in males and by identifying the specific GLA gene mutation in male and female patients. Treatment with enzyme replacement therapy, as part of the therapeutic strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline, particularly in the early stages of the disease. Emergent treatments for FD include the recently approved chaperone molecule migalastat for patients with amenable mutations. The objective of this report is to provide an updated overview on Fabry nephropathy, with a focus on the most relevant aspects of its epidemiology, diagnosis, pathophysiology, and treatment options.