Phase 1 Mass Balance Study of Pizuglanstat: An Investigational Hematopoietic Prostaglandin D Synthase Inhibitor

Pizuglanstat is a novel hematopoietic prostaglandin D synthase inhibitor and investigational treatment for Duchenne muscular dystrophy. This Phase 1 mass balance study aimed to characterize the absorption, metabolism, and excretion of carbon-14 (¹⁴C)-labeled pizuglanstat in healthy adults (ClinicalTrials.gov, NCT04825431). After administering a single oral dose of [¹⁴C]pizuglanstat solution containing 400 mg of pizuglanstat and 1 megabecquerel of radioactivity to 6 healthy men (median age, 26 years), pizuglanstat in plasma reached a maximal concentration after a median of 0.5 hour and declined with a geometric mean half-life of 7.7 hours. Pizuglanstat and its metabolites were primarily excreted via the fecal route; on average, 66.1% of administered radioactivity was excreted in feces after 168 hours, compared with 32.2% excreted in urine. Pizuglanstat was mostly present as the unchanged parent molecule in plasma, urine, and feces, while the sulfate conjugate of hydroxyl pizuglanstat was the major metabolite in each sample type. Two adverse drug reactions of urticaria were reported in 2 participants (33.3%); both events were nonsevere and manageable with treatment, and no other clinically significant safety events were observed. Overall, this study provides important pharmacokinetic, mass balance, and safety data to support the development of pizuglanstat as a new treatment for Duchenne muscular dystrophy.