Statistical methodology for highly variable compounds: A novel design approach for the ofatumumab Phase 2 bioequivalence study.

This article describes a novel mixed-scaling testing strategy, in combination with an adaptive parallel-groups bioequivalence trial, to test pharmacokinetic equivalence of two formulations of a drug with highly variable pharmacokinetics. The methodology was applied to the Phase 2 APLIOS study in relapsing multiple sclerosis patients, where the bioequivalence of subcutaneous ofatumumab 20 mg administered via an autoinjector pen (test formulation) versus prefilled syringe (reference formulation) in the abdomen has been studied. Due to a high coefficient of variation (CV) of the relevant pharmacokinetic metrics (AUC and C ) for the reference formulation (>30%), a reference-Scaled bioequivalence (RSABE) approach was applied but modified for a parallel-groups design.