Franklin K. Johnson

Treatment of Fabry’s Disease with the Pharmacologic Chaperone Migalastat

BACKGROUND Fabrys disease, an X-linked disorder of lysosomal α-galactosidase deficiency, leads to substrate accumulation in multiple organs. Migalastat, an oral pharmacologic chaperone, stabilizes specific mutant forms of α-galactosidase, increasing enzyme trafficking to lysosomes. METHODS The initial assay of mutant α-galactosidase forms that we used to categorize 67 patients with Fabrys disease for randomization to 6 months of double-blind migalastat or placebo (stage 1), followed by open-label migalastat from 6 to 12 months (stage 2) plus an additional year, had certain limitations. Before unblinding, a new, validated assay showed that 50 of the 67 participants had mutant α-galactosidase forms suitable for targeting by migalastat. The primary end point was the percentage of patients who had a response (≥50% reduction in the number of globotriaosylceramide inclusions per kidney interstitial capillary) at 6 months. We assessed safety along with disease substrates and renal, cardiovascular, and patient-reported outcomes. RESULTS The primary end-point analysis, involving patients with mutant α-galactosidase forms that were suitable or not suitable for migalastat therapy, did not show a significant treatment effect: 13 of 32 patients (41%) who received migalastat and 9 of 32 patients (28%) who received placebo had a response at 6 months (P=0.30). Among patients with suitable mutant α-galactosidase who received migalastat for up to 24 months, the annualized changes from baseline in the estimated glomerular filtration rate (GFR) and measured GFR were -0.30±0.66 and -1.51±1.33 ml per minute per 1.73 m(2) of body-surface area, respectively. The left-ventricular-mass index decreased significantly from baseline (-7.7 g per square meter; 95% confidence interval [CI], -15.4 to -0.01), particularly when left ventricular hypertrophy was present (-18.6 g per square meter; 95% CI, -38.2 to 1.0). The severity of diarrhea, reflux, and indigestion decreased. CONCLUSIONS Among all randomly assigned patients (with mutant α-galactosidase forms that were suitable or not suitable for migalastat therapy), the percentage of patients who had a response at 6 months did not differ significantly between the migalastat group and the placebo group. (Funded by Amicus Therapeutics; ClinicalTrials.gov numbers, NCT00925301 [study AT1001-011] and NCT01458119 [study AT1001-041].).

Oral pharmacological chaperone migalastat compared with enzyme replacement therapy in Fabry disease: 18-month results from the randomised phase III ATTRACT study

Background Fabry disease is an X-linked lysosomal storage disorder caused by GLA mutations, resulting in α-galactosidase (α-Gal) deficiency and accumulation of lysosomal substrates. Migalastat, an oral pharmacological chaperone being developed as an alternative to intravenous enzyme replacement therapy (ERT), stabilises specific mutant (amenable) forms of α-Gal to facilitate normal lysosomal trafficking. Methods The main objective of the 18-month, randomised, active-controlled ATTRACT study was to assess the effects of migalastat on renal function in patients with Fabry disease previously treated with ERT. Effects on heart, disease substrate, patient-reported outcomes (PROs) and safety were also assessed. Results Fifty-seven adults (56% female) receiving ERT (88% had multiorgan disease) were randomised (1.5:1), based on a preliminary cell-based assay of responsiveness to migalastat, to receive 18 months open-label migalastat or remain on ERT. Four patients had non-amenable mutant forms of α-Gal based on the validated cell-based assay conducted after treatment initiation and were excluded from primary efficacy analyses only. Migalastat and ERT had similar effects on renal function. Left ventricular mass index decreased significantly with migalastat treatment (−6.6 g/m2 (−11.0 to −2.2)); there was no significant change with ERT. Predefined renal, cardiac or cerebrovascular events occurred in 29% and 44% of patients in the migalastat and ERT groups, respectively. Plasma globotriaosylsphingosine remained low and stable following the switch from ERT to migalastat. PROs were comparable between groups. Migalastat was generally safe and well tolerated. Conclusions Migalastat offers promise as a first-in-class oral monotherapy alternative treatment to intravenous ERT for patients with Fabry disease and amenable mutations. Trial registration number: NCT00925301; Pre-results.

Oral Migalastat HCl Leads to Greater Systemic Exposure and Tissue Levels of Active α-Galactosidase A in Fabry Patients when Co-Administered with Infused Agalsidase

Migalastat HCl (AT1001, 1-Deoxygalactonojirimycin) is an investigational pharmacological chaperone for the treatment of α-galactosidase A (α-Gal A) deficiency, which leads to Fabry disease, an X-linked, lysosomal storage disorder. The currently approved, biologics-based therapy for Fabry disease is enzyme replacement therapy (ERT) with either agalsidase alfa (Replagal) or agalsidase beta (Fabrazyme). Based on preclinical data, migalastat HCl in combination with agalsidase is expected to result in the pharmacokinetic (PK) enhancement of agalsidase in plasma by increasing the systemic exposure of active agalsidase, thereby leading to increased cellular levels in disease-relevant tissues. This Phase 2a study design consisted of an open-label, fixed-treatment sequence that evaluated the effects of single oral doses of 150 mg or 450 mg migalastat HCl on the PK and tissue levels of intravenously infused agalsidase (0.2, 0.5, or 1.0 mg/kg) in male Fabry patients. As expected, intravenous administration of agalsidase alone resulted in increased α-Gal A activity in plasma, skin, and peripheral blood mononuclear cells (PBMCs) compared to baseline. Following co-administration of migalastat HCl and agalsidase, α-Gal A activity in plasma was further significantly increased 1.2- to 5.1-fold compared to agalsidase administration alone, in 22 of 23 patients (95.6%). Importantly, similar increases in skin and PBMC α-Gal A activity were seen following co-administration of migalastat HCl and agalsidase. The effects were not related to the administered migalastat HCl dose, as the 150 mg dose of migalastat HCl increased α-Gal A activity to the same extent as the 450 mg dose. Conversely, agalsidase had no effect on the plasma PK of migalastat. No migalastat HCl-related adverse events or drug-related tolerability issues were identified. Trial Registration ClinicalTrials.gov NCT01196871

Pharmacokinetics and Safety of Migalastat HCl and Effects on Agalsidase Activity in Healthy Volunteers

Migalastat HCl is an investigational, oral treatment for Fabry disease, an X‐linked lysosomal storage disorder. Four Phase 1 studies were conducted to determine the pharmacokinetics, pharmacodynamics, safety, and tolerability of migalastat. Healthy volunteers (N = 124), 18–55 years old, received migalastat HCl single (25 mg–2000 mg) or twice‐daily doses (50 mg, 150 mg) for 7 days in a double‐blind, placebo‐controlled fashion. Migalastat pharmacokinetics were dose‐proportional (AUC∞ range: 1129–72 838 ng h/mL, Cmax range: 200.5–13 844 ng/mL, t1/2 3–4 hours). Steady state was achieved by Day 7. Up to 67% of the dose was excreted as unchanged drug in urine. Increased α‐Gal A activity was dose related. No abnormal cardiac effects, including prolonged QTc intervals, were observed. The pharmacokinetics of migalastat were well characterized in these Phase 1 studies conducted healthy volunteers. The 150 mg dose of migalastat HCl administered BID for 7 days was generally safe and well tolerated. A TQT study demonstrated lack of a positive signal at therapeutic and supra‐therapeutic doses. Increases in α‐Gal A enzyme activity for the 150 mg dose observed in healthy subjects suggested a successful proof of mechanism for further investigations.

Duvoglustat HCl Increases Systemic and Tissue Exposure of Active Acid α-Glucosidase in Pompe Patients Co-administered with Alglucosidase α

Duvoglustat HCl (AT2220, 1-deoxynojirimycin) is an investigational pharmacological chaperone for the treatment of acid α-glucosidase (GAA) deficiency, which leads to the lysosomal storage disorder Pompe disease, which is characterized by progressive accumulation of lysosomal glycogen primarily in heart and skeletal muscles. The current standard of care is enzyme replacement therapy with recombinant human GAA (alglucosidase alfa [AA], Genzyme). Based on preclinical data, oral co-administration of duvoglustat HCl with AA increases exposure of active levels in plasma and skeletal muscles, leading to greater substrate reduction in muscle. This phase 2a study consisted of an open-label, fixed-treatment sequence that evaluated the effect of single oral doses of 50 mg, 100 mg, 250 mg, or 600 mg duvoglustat HCl on the pharmacokinetics and tissue levels of intravenously infused AA (20 mg/kg) in Pompe patients. AA alone resulted in increases in total GAA activity and protein in plasma compared to baseline. Following co-administration with duvoglustat HCl, total GAA activity and protein in plasma were further increased 1.2- to 2.8-fold compared to AA alone in all 25 Pompe patients; importantly, muscle GAA activity was increased for all co-administration treatments from day 3 biopsy specimens. No duvoglustat-related adverse events or drug-related tolerability issues were identified.

An open‐label study to determine the pharmacokinetics and safety of migalastat HCl in subjects with impaired renal function and healthy subjects with normal renal function

Renal function may progressively decline in patients with Fabry disease. This study assessed pharmacokinetics, safety, and tolerability of a single oral dose of migalastat HCl 150 mg in subjects with normal or mildly, moderately, or severely impaired renal function.

Relative bioavailability and the effect of meal type and timing on the pharmacokinetics of migalastat in healthy volunteers

Migalastat HCl is an investigational, pharmacological chaperone for mutant α‐galactosidase A, which is responsible for Fabry disease, an X‐linked, lysosomal storage disorder. Two Phase I studies evaluated relative bioavailability, effect of meal type and timing on pharmacokinetics, safety, and tolerability of migalastat HCl in healthy volunteers. Study 1 (N = 15, 19–55 years): single 100‐mg doses of migalastat HCl capsule and solution formulations were bioequivalent. The ratios of LSM (90% CIs) for Cmax were 97.1% (86.8–109) and AUC0‐inf 97.9% (88.8–108) under fasted conditions. Single 100‐mg doses of migalastat HCl capsules administered with a high‐fat meal decreased Cmax by 40% and AUC0‐inf by 37%. A high‐fat meal delayed tmax by approximately 1 hour. Study 2 (N = 20, 18–65 years): A high‐fat or light meal up to 1 hour before or after administration of single 150 mg doses of migalastat HCl capsules decreased Cmax and AUC0‐inf up to 40%, but had no apparent effect on tmax (range of medians with food: 1.5–3 hours, median fasted: 3 hours). A 50‐g glucose drink co‐administered with migalastat HCL did not result in clinically significant changes in migalastat absorption. No serious safety or tolerability issues were identified.

T.P.46 A novel phase 2a study design to investigate drug-drug interactions between escalating doses of AT2220 (duvoglustat hydrochloride) and acid alpha-glucosidase in subjects with Pompe disease

Abstract Pompe disease is an inherited lysosomal storage disease that results from a deficiency in acid alpha-glucosidase (GAA) activity, and is characterized by progressive accumulation of lysosomal glycogen primarily in heart and skeletal muscles. Recombinant human GAA (rhGAA, Genzyme) is the only approved enzyme replacement therapy for Pompe, and is administered biweekly via intravenous infusion. While rhGAA provides clinical benefit, drawbacks as low stability at neutral pH/body temperature, modest tissue uptake and glycogen reduction, and immune responses affect tolerability and efficacy. AT2220 (1-deoxynojirimycin; duvoglustat HCl) is a pharmacological chaperone that selectively and reversibly binds and stabilizes endogenous GAA, facilitating proper folding and trafficking to lysosomes. AT2220-010 is an open-label, single ascending dose, fixed-sequence, two-period, dose-finding study comprised of four cohorts of 4–6 subjects with Pompe disease. Study objectives: (1) evaluate the safety of single ascending doses of AT2220 co-administered with rhGAA, and (2) characterize the pharmacokinetic interaction of AT2220 and rhGAA on activity and protein levels in plasma, muscle, and peripheral blood mononuclear cells, and on urine Hex four levels. Period 1, subjects receive rhGAA alone, then Period 2 they receive a single oral dose of AT2220 with rhGAA. Safety data from each completed dose cohort is reviewed by a Data Safety Monitoring Board. An innovative muscle biopsy technique, which requires specialized investigator training, is used to sample quadricep muscle either on Day 3 or 7 of each period. This unique crossover study design allows for meaningful evaluation of safety and pharmacokinetic data in the rare disease field by allowing each subject to serve as their own control and reducing variability as opposed to parallel designs requiring larger sample sizes for statistical comparisons.