Development of a Population Pharmacokinetic Model for the Diroximel Fumarate Metabolites Monomethyl Fumarate and 2-Hydroxyethyl Succinimide Following Oral Administration of Diroximel Fumarate in Healthy Participants and Patients with Multiple Sclerosis.

INTRODUCTION: Diroximel fumarate (DRF) is a next-generation oral fumarate that is indicated in the USA for relapsing forms of multiple sclerosis (MS). A joint population pharmacokinetic model was developed for the major active metabolite (monomethyl fumarate, MMF) and the major inactive metabolite (2-hydroxyethyl succinimide, HES) of DRF. METHODS: MMF and HES data were included from 341 healthy volunteers and 48 patients with MS across 11 phase I and III studies in which DRF was administered as single or multiple doses. Population modeling was performed with NONMEM version 7.3 with the first-order conditional estimation method. RESULTS: Estimated MMF clearance (CLMMF), volume of distribution, and absorption rate constant (Ka) were 13.5 L/h, 30.4 L, and 5.04 h-1, respectively. CLMMF and HES clearance (CLHES) increased with increasing body weight. CLHES decreased with decreasing renal function. CLMMF and CLHES were 28% and 12% lower in patients with MS than in healthy volunteers, respectively. Ka was reduced in the presence of low-, medium-, and high-fat meals by 37%, 51%, and 67%, respectively, for MMF; and by 34%, 49%, and 62%, respectively, for HES. CONCLUSIONS: Age, sex, race, and baseline liver function parameters such as total bilirubin, albumin, and aspartate aminotransferase were not considered to be significant predictors of MMF or HES disposition.

Comparison of neurofilament light chain results between two independent facilities.

OBJECTIVES: To examine levels of neurofilament light chain (NFL) in identical cerebrospinal fluid (CSF) and blood samples at two different facilities, and how differences affect interpretation of levels within and above the normal range. METHODS: CSF and plasma from patients with multiple sclerosis (MS) and healthy controls (HCs) were analysed by Simoa (Quanterix) for levels of NFL providing a total of 165 CSF samples (119 from MS) and 225 plasma samples (180 from MS). RESULTS: CSF and plasma concentrations highly correlated between NFL laboratory facilities (R: 0.92 and 0.84, <0.0001, respectively), and there were no differences between facilities. A bias between the two sites for plasma was -0.95 pg/mL and for CSF -73.53 pg/mL. The cut-offs for CSF were 807.5 and 571.0 pg/mL at site 1 and site 2, respectively; the cut-offs for plasma were 13.0 and 11.8 pg/mL, respectively. Seven out of 180 plasma samples (3.9%) and 3 out of 119 CSF samples (2.5%) from MS patients could be reclassified as normal/abnormal, that is, below/above cut-off, when measured at different facilities. CONCLUSION: Our study demonstrates that results of NFL in CSF and blood measured with SIMOA are comparable between facilities. Nevertheless, healthcare practitioners should consider reference values at different laboratories, since different sensitivity/specificity can affect interpretation when low values are adjacent to cut-offs.

Dimethyl fumarate decreases neurofilament light chain in CSF and blood of treatment naïve relapsing MS patients.

OBJECTIVES: In a prospective phase IV trial of the first-line oral treatment dimethyl fumarate (DMF), we examined dynamics of neurofilament light (NFL) chain in serum, plasma and cerebrospinal fluid (CSF) samples collected over 12 months from relapsing-remitting multiple sclerosis (RRMS) patients. NFL changes were related to disease activity. METHODS: We examined NFL levels by single-molecule array in 88 CSF, 348 plasma and 131 sera from treatment-naïve RRMS patients (n=52), healthy controls (n=23) and a placebo group matched by age, sex and NFL (n=52). Plasma/sera were collected at baseline, and 1, 3, 6 and 12 months after DMF. CSF samples were collected at baseline and 12 months after DMF. RESULTS: NFL concentration in CSF, plasma and serum correlated highly (p<0.0001 for all), but plasma levels were only 76.9% of paired serum concentration. After 12 months of DMF treatment, NFL concentration decreased by 73%, 69% and 55% in the CSF, serum and plasma (p<0.0001, respectively). Significant reduction in blood was observed after 6 and 12 months treatment compared with baseline (p<0.01 and p<0.0001, respectively) and to placebo (p<0.0001). Patients with NFL above the 807.5 pg/mL cut-off in CSF had 5.0-times relative risk of disease activity (p<0.001). CONCLUSIONS: This study provides Class II evidence that first-line DMF reduces NFL in both blood and CSF after 6 months and normalises CSF levels in 73% of patients. High NFL concentration in CSF after a year reflected disease activity. NFL levels were higher in serum than in plasma, which should be considered when NFL is used as a biomarker.

Improving the Gastrointestinal Tolerability of Fumaric Acid Esters: Early Findings on Gastrointestinal Events with Diroximel Fumarate in Patients with Relapsing-Remitting Multiple Sclerosis from the Phase 3, Open-Label EVOLVE-MS-1 Study.

INTRODUCTION: Diroximel fumarate (DRF) is a novel oral fumarate in development for patients with relapsing forms of multiple sclerosis (MS). Clinical findings from the DRF development program suggest that rates of gastrointestinal (GI) treatment-emergent adverse events (TEAEs) and discontinuation due to GI TEAEs are low, based on clinical and real-world observations of other fumaric acid esters, including dimethyl fumarate (DMF). The incidence of GI TEAEs varies from 40 to 88% in clinical and real-world studies of DMF. The objective of this study is to present GI tolerability findings from the EVOLVE-MS-1 study and present biologic hypotheses for the improved GI properties of DRF. METHODS: GI TEAEs and treatment discontinuation because of GI TEAEs were assessed in DRF-treated patients with relapsing-remitting MS who were participating in the ongoing, 96-week, open-label, phase 3 EVOLVE-MS-1 study. RESULTS: As of March 30, 2018, a total of 696 patients were enrolled in EVOLVE-MS-1. GI TEAEs were reported in 30.9% (215/696) of patients; the vast majority (96%; 207/215) experienced events that were mild or moderate in severity. When GI AEs did occur, they occurred early in treatment, resolved (88.8%; 191/215), and were of short duration [median 7.5 (range 1-87) days] in most patients. GI TEAEs led to < 1% of patients discontinuing treatment. CONCLUSIONS: We suggest that the distinct chemical structure of DRF contributes to the observed low rates of GI TEAEs and GI-associated treatment discontinuations, possibly due to a combination of several factors. We hypothesize that these factors may include less reactivity with off-target proteins and/or lower production of a methanol leaving group that may contribute to GI irritation. A direct comparison of GI tolerability with DRF versus DMF is being evaluated in the EVOLVE-MS-2 study. TRIAL REGISTRATION: ClinicalTrials.gov number NCT02634307. FUNDING: Alkermes Inc. (Waltham, MA, USA) and Biogen (Cambridge, MA, USA).

Safety and Efficacy of Delayed-Release Dimethyl Fumarate in Pediatric Patients With Relapsing Multiple Sclerosis (FOCUS).

BACKGROUND: No therapies have been formally approved by the Food and Drug Administration for use in pediatric multiple sclerosis, a rare disease. OBJECTIVE: We evaluated the safety, efficacy, and pharmacokinetics of dimethyl fumarate in pediatric patients with multiple sclerosis. METHODS: FOCUS, a phase 2, multicenter study of patients aged 10 to 17 years with relapsing-remitting multiple sclerosis, comprised an eight-week baseline and 24-week treatment period; during treatment, patients received dimethyl fumarate (120 mg twice daily on days one to seven; 240 mg twice a day thereafter). Magnetic resonance imaging scans were obtained at week -8, day 0, week 16, and week 24. The primary end point was the change in T2 hyperintense lesion incidence from the baseline period to the final 8 weeks of treatment. Secondary end points were pharmacokinetic parameters and adverse event incidence. RESULTS: Twenty of 22 enrolled patients completed the study. There was a significant reduction in T2 hyperintense lesion incidence from baseline to the final eight weeks of treatment (P = 0.009). Adverse events (most commonly gastrointestinal events and flushing) and pharmacokinetic parameters were consistent with adult findings. No serious adverse events were considered dimethyl fumarate related. CONCLUSIONS: Dimethyl fumarate treatment was associated with a reduction in magnetic resonance imaging activity in pediatric patients; pharmacokinetic and safety profiles were consistent with those in adults. Dimethyl fumarate is a potential treatment for pediatric multiple sclerosis.