First human exposure to FSH-CTP in hypogonadotrophic hypogonadal males

This is the first report of human exposure to the novel compound follicle stimulating hormone (FSH)-C-terminal peptide (CTP) 'FSH-CTP' (Org 36286), a long-acting recombinant FSH like substance, consisting of the alpha-subunit of human FSH and a hybrid beta-subunit. The latter is composed of the beta-subunit of human FSH and the C-terminus part (CTP) of the beta-subunit of human chorionic gonadotrophin (HCG).

In this phase I, non-blind, multi-centre study, 13 hypogonadotrophic hypogonadal male subjects were enrolled to test the safety of FSH-CTP in terms of antibody formation in humans. Furthermore, the pharmacokinetic profile of this new compound was determined. Subjects were injected four times with 15 microg FSH-CTP with an interval of approximately 4 weeks between each injection.

No drug related (serious) adverse events occurred. No antibodies against FSH-CTP or chinese hamster ovary (CHO)-cell derived proteins were detected and measurement of local tolerance demonstrated that s.c. administration of FSH-CTP is well tolerated and no increase in intensity of injection-site responses was observed after repeated exposure to FSH-CTP. After the first and third injection, FSH-CTP serum concentrations were determined. Overall mean (+/- SD) C(max) was 0.426 (+/- 0.116) ng/ml, mean t(1/2) and AUC(0-infinity) were 94.7 (+/- 26.2) h and 81.5 (+/- 18.8) ng.h/ml respectively. Compared with recFSH (Puregon), the half life of FSH-CTP was increased 2-3 times. Following the first and third injection a clear rise in serum inhibin-B concentrations were observed.

The use of FSH-CTP is safe and does not lead to detectable formation of antibodies. Furthermore, the pharmacokinetic and dynamic profile of FSH-CTP may lead to the development of new, more convenient regimens for the treatment of male and female infertility.