A comparative pharmacokinetic and pharmacodynamic study of FSK0808 versus reference filgrastim after repeated subcutaneous administration in healthy Japanese men

Survey of Data Package and Sample Size of Comparative Clinical Studies for Biosimilar Developments from PMDA Assessments

BACKGROUND

The Japanese biosimilar guideline requires that the sponsors conduct clinical studies such as comparative pharmacokinetic (PK), pharmacodynamic (PD), or efficacy studies. In each biosimilar development, the sponsors consider the clinical data package, and thus clinical data packages vary among biosimilar developments.

OBJECTIVES

The aim of this study was to elucidate the clinical data packages for the biosimilars approved in Japan. The details of clinical data packages and sample size for the regulatory approvals of biosimilars in Japan was reported.

METHODS

We surveyed the clinical data packages and sample size based on the Pharmaceuticals and Medical Devices Agency (PMDA) website review reports between 2009 and 2023.

RESULTS

Twenty-four biosimilars have been approved based on the comparative PK and efficacy studies, 10 biosimilars have been approved based on the comparative PK/PD study, and one biosimilar has been approved based on the comparative efficacy study. Regarding the sample size, comparative PK studies were conducted in healthy volunteers or patients for up to 300 cases, although the majority enrolled only 1-100 cases (68.1%, 32/47). Comparative PD studies enrolling 1-30, 31-60, and 61-90 cases totaled 4, 7, and 4 cases, respectively. Finally, comparative efficacy studies enrolling 1-300, 301-600, and 601-900 totaled 6, 10, and 11 cases, respectively. In particular, the oncology and rheumatology areas were the first and second disease areas recruiting 601-900 patients.

CONCLUSION

Large numbers of patients were enrolled to conduct a comparative efficacy study. Efficient biosimilar development should be considered on the basis of the accumulation of scientific understanding of comparable features of biosimilars and their development.

Comparison of biosimilar filgrastim with a reference product: pharmacokinetics, pharmacodynamics, and safety profiles in healthy volunteers

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.

Update on biosimilars of granulocyte colony-stimulating factor - when no news is good news

PURPOSE OF REVIEW

With the approval of the first biosimilar granulocyte colony-stimulating factor (G-CSF), biosimilars - copies of therapeutic biologicals whose patent protection has expired - have finally reached the US healthcare market. Its advent is an occasion for a closer look at recent insights into biosimilar G-CSF and an attempt at prognosticating the future (future role) of biosimilars in general.

RECENT FINDINGS

Recent literature regarding biosimilar G-CSF orbits significantly around patient access and effects on healthcare expenditure. The advent of biosimilar G-CSF has induced unexpectedly large price reductions for short-acting G-CSF. On the clinical side, little excitement is tangible, probably appropriately so, since clinical data indicate nothing short of biological similarity. Although formal clinical trials are few, the plethora of case series and historic comparisons which have come forth offer reassurance about the appropriateness of the regulators' assessment of biosimilar G-CSF as indeed in all respects biologically similar to the originator.

SUMMARY

All evidence points to an overwhelming similarity of originator and biosimilar G-CSF in all indications. Overall clinical acceptance, albeit possibly significantly dictated by economic pressures, is good. Price reductions exceed predictions and may jeopardize the economic viability of biosimilar programs. A concurrent shift towards long-acting G-CSF ('biobetters') is observed in Europe.