A Phase I, Open-label, Randomized, Crossover Study of the Relative Bioavailability of Capsule and Granule Formulations of Selumetinib

Selumetinib (ARRY-142886) is an oral, potent, and highly selective allosteric mitogen-activated protein kinase kinase 1/2 inhibitor approved for the treatment of pediatric patients (≥2 years of age) with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. This Phase I crossover study (NCT03649165) evaluated the pharmacokinetic properties and palatability of a new granule formulation of selumetinib.Healthy volunteers were randomized to 1 of 2 sequences; selumetinib granule (25 mg) followed by selumetinib capsules (50 mg [2 × 25 mg]) and vice versa. The primary end point was the pharmacokinetic properties of the 2 formulations. Secondary end points included safety and tolerability of single selumetinib doses and palatability of the granule formulation.Of the 24 enrolled volunteers (mean age, 33.2 years; range 23-44 years), all were male and 20 (83%) were Black/African American. Under fasted conditions for the granule versus capsule, geometric mean ratios for the dose-normalized Cmax and AUC0-∞ were 0.654 (90% CI, 0.581-0.736) and 0.865 (90% CI, 0.811-0.922), respectively. Absorption of selumetinib was similar between granule and capsule formulation, with a median time to Cmax of 1.73 hours and 1.14 hours, respectively. Adverse event incidence was low (n = 6 in both groups), and most events were mild. Palatability was acceptable, with volunteers indicating that they would take the granule formulation again.These findings support further research into the selumetinib granule formulation, with the aim of producing an alternative formulation for younger children or patients unable to swallow capsules.gov identifier: NCT03649165.