Æterna Zentaris Inc. along with its Japanese partner Shionogi & Co., Ltd. have announced positive results for a phase 2a trial with cetrorelix in benign prostatic hyperplasia (BPH) initiated in 2005 in Japan. Results showed that cetrorelix, the company's lead luteinizing hormone-releasing hormone (LHRH) antagonist, was safe and well tolerated at all dosage regimens.

Furthermore, Japanese patients responded to cetrorelix with a transient reduction of testosterone concentration in blood, which did not reach or remain at the castration level. Additionally, none of the dosage regimens tested caused a suppression of PSA levels. Finally, data generated with Japanese patients showed that the bioavailability of cetrorelix was similar to that observed in non-Japanese patients.

On the basis of this study, Shionogi initiated a 300-patient phase 2b study to assess primarily the efficacy of cetrorelix in BPH in Japanese patients.

"We are very pleased with these results which further confirm the positive data observed in prior clinical trials in BPH with cetrorelix in non-Asian patients", said Gilles Gagnon, president and CEO of Æterna Zentaris. "Shionogi's decision to initiate a phase 2b trial in BPH combined with our own ongoing Phase 3 program with cetrorelix in this same indication, allows us to pursue the development of cetrorelix at an international level and represents an opportunity to potentially gain access to large markets worldwide".

Nippon Kayaku, the company's other Japanese partner, has terminated its agreement with respect to their collaboration with the development of cetrorelix pamoate to focus solely in oncology.