A Phase 1 Randomized, Placebo-Controlled, Double-Blind, Escalating Single-Dose Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of ManNAc in Subjects With GNE Myopathy or Hereditary Inclusion Body Myopathy (HIBM)

Hereditary inclusion body myopathy (HIBM) is an autosomal recessive, neuromuscular disorder characterized by progressive muscle weakness with onset in early adulthood. The causative gene, GNE, codes for the bifunctional enzyme uridine diphospho-N-acetylglucosamine (UDP-GlcNAc)-2-epimerase/N-acetylmannosamine (ManNAc) kinase (GNE/MNK), which catalyzes the first 2 steps in the biosynthesis of sialic acid. The subsequent paucity of sialic acid production is presumed to cause decreased sialylation of HIBM muscle glycoproteins, resulting in muscle deterioration. In this Phase 1, randomized, placebo-controlled, double-blind, escalating single-dose study, we propose to provide ManNAc (N-acetyl-D-mannosamine monohydrate) orally as a liquid solution to 3 cohorts of 6 subjects (Cohorts A, B, C) at doses of 3,000 mg, 6,000 mg, and 10,000 mg ManNAc, respectively, or up to the maximum tolerated dose (MTD). The objectives of this study are to evaluate the safety, tolerability, and pharmacokinetics (PK) of a single dose of orally administered ManNAc to HIBM subjects, to identify the MTD of a single dose of orally administered ManNAc to HIBM subjects, and to explore the effect of a single dose of ManNAc on potential pharmacodynamic (PD) markers of HIBM. All subjects will be randomly assigned in a 2:1 ratio to receive ManNAc (n equals 4) or placebo (n equals 2) and the decision to dose-escalate will be the responsibility of the Safety Review Committee (SRC). Safety will be assessed by adverse events (AEs), clinical laboratory tests, vital signs, physical examinations, and electrocardiograms (ECGs). PK will be assessed for both ManNAc and sialic acid.