Purpose: Filgrastim, a granulocyte-colony stimulating factor, is used to treat patients with neutropenia, including neutropenic fever. Leucostim® is a recombinant filgrastim product tested for biosimilarity with its reference product, Neupogen®. We conducted a comparative clinical trial of the 2 products.
Patients and methods: A randomized, open-label, 2-way crossover, single-dose Phase I study was conducted for 56 healthy subjects. After a 5 and 10 μg/kg single subcutaneous administration of test and reference product, pharmacokinetic and pharmacodynamic parameters (absolute neutrophil count and CD34+ cell count) were compared. During the study, safety tests and adverse event monitoring were performed.
Results: The test and the reference products had a comparable pharmacokinetic, pharmacodynamic, and safety profile. In both 5 and 10 μg/kg dosing, the 90% CIs of the test to reference ratio for primary parameters (peak plasma concentration and area under the plasma concentration vs time curve from time 0 extrapolated to the infinite time for plasma filgrastim concentration; maximal effect and area under the time-effect curve from time 0 to time of the last quantifiable effect for absolute neutrophil count) were within the 0.8-1.25 range. In addition, safety profiles between the 2 products were similar without any serious adverse events.
Conclusion: This study has provided firm clinical evidence that the test filgrastim product is similar to its reference filgrastim product.
Keywords: G-CSF; bioequivalence; biologics; biosimilar.