Comparability of Biosimilar Filgrastim with Originator Filgrastim: Protein Characterization, Pharmacodynamics, and Pharmacokinetics

BACKGROUND: Biosimilars provide safety, purity, and potency similar to those of a reference biologic product. METHODS: An array of protein analytical techniques was used to compare the physicochemical properties of proposed biosimilar filgrastim (EP2006), US-approved originator filgrastim, and EU-approved originator filgrastim. Biological characterization involved surface plasmon resonance spectroscopy analyses and in vitro proliferation assays. A randomized, double-blind, two-way crossover, phase I study in healthy volunteers assessed the pharmacodynamics, pharmacokinetics, and safety profiles of EP2006 and US-approved originator filgrastim (administered as a single subcutaneous 10 µg/kg injection). RESULTS: EP2006 and originator filgrastim (US and EU approved) were highly similar with respect to primary, secondary, and tertiary protein structures; mass, size, purity, charge, and hydrophobicity. No differences in receptor binding affinity were observed, and all samples demonstrated similar in vitro bioactivity. In the phase I study, no statistically significant differences between EP2006 and US-approved originator filgrastim were noted in pharmacodynamic or pharmacokinetic parameters, and all confidence intervals were within the equivalence boundaries. The two products had similar safety profiles. CONCLUSION: These studies provide robust evidence of the structural and functional similarity between the proposed biosimilar filgrastim (EP2006) and the US-approved originator filgrastim.