Endocrine Abstracts

Introduction: Follicle-stimulating hormone (FSH) biosimilars, differing for source cell and glycosylation pattern, are commercially available for therapy of hypogonadism and assisted reproduction techniques (ART). Although these molecules are commonly used in clinical practice, comparison of their action in vitro was poorly investigated.

Aim: The aim of the study is to compare recombinant FSH- and biosimilars-induced cell response in vitro.

Material and methods: Different batches of FSH and biosimilars were used, i.e. recombinant FSH Gonal-F^® (Merck KGaA, Darmstadt, Germany), Bemfola^® 150, 300 and 450 (Finox Biotech, Kirchberg, Switzerland) and Ovaleap^® 450 and 900 (Teva Pharmaceutical Industries, Basel, Switzerland). Human primary granulosa lutein cells (hGLC), as well as FSH receptor (FSHR)-transfected HEK293 cells were stimulated by increasing doses of FSH or biosimilar (1-100 nM range). Intracellular cAMP and Ca²⁺ production as well as β-arrestin two recruitment were evaluated by BRET. Moreover, CREB and ERK phosphorylation was evaluated by Western blotting analysis. Finally, 8- and 24-h progesterone and estradiol synthesis were investigated by immunoassay.

Results: While no different cAMP and β-arrestin two recruitment were detected in FSHR-transfected HEK293 cells (cAMP EC50 range=6±0.09 – 19±0.07 ng/ml; β-arrestin two EC50 range=72±0.27 – 489±0.26 ng/ml; Mann-Whitney’s U test; P>0.05; n=4), Ovaleap^® induced lower levels of pCREB and pERK1/2 activation than other biosimilars in hGLC (Mann-Whitney’s U test; P<0.05; n=4). Kinetics analysis revealed no intracellular Ca2+ increase upon treatment by 4.4 μg/ml Ovaleap^® and Bemfola^® (Mann-Whitney’s U test; P<0.05; n=4), while treatment of FSHR-transfected HEK293 cells by 4.4 μg/ml Gonal-F^® rapidly induced intracellular Ca²⁺ peak. In hGLC, FSH and biosimilars induced both 8- and 24-h progesterone and estradiol synthesis, but no differences were found between the EC50s and plateau levels (n=4).

Discussion: Preparation-specific intracellular signaling patterns were activated by recombinant FSH and biosimilars, but the downstream steroid synthesis was similar. Especially, biosimilars failed to induce intracellular Ca2+ increase.

Conclusions: Recombinant and biosimilar drugs used in clinical practice as equivalent, are linked to specific intracellular signaling in vitro. Results may be relevant for their use in vivo.