All amounts are in US dollars QUEBEC CITY, April 19 /PRNewswire-FirstCall/ -- AEterna Zentaris Inc. (TSX: AEZ; Nasdaq: AEZS), a global biopharmaceutical company focused on endocrine therapy and oncology, today reported dosing has commenced with its flagship product candidate, cetrorelix, the Company's lead luteinizing hormone-releasing hormone (LHRH) antagonist compound, in the first study of its Phase 3 program in benign prostatic hyperplasia (BPH). As previously announced, the first study of the Phase 3 program titled, "Cetrorelix pamoate intermittent IM dosage regimens in patients with symptomatic BPH: a 1-year placebo-controlled efficacy study and long-term safety assessment", will assess an intermittent dosage regimen of cetrorelix as a potential safe and tolerable treatment providing prolonged improvement in BPH-related signs and symptoms, under the supervision of Lead Investigator, Herbert Lepor, M.D., Professor and Martin Spatz Chairman of Urology, at the New York University School of Medicine. "We are very excited to report our first patients being treated with cetrorelix in our extensive Phase 3 program in BPH," stated David J. Mazzo, Ph.D., President and CEO of AEterna Zentaris. "We expect recruitment to progress swiftly over the remainder of the year as the vast majority of our 10 centers in Canada and 30 centers in the United States will be up and running by the end of the month. This event also marks a key milestone in our drug development strategy as it brings our flagship product candidate yet another step closer to an NDA filing. We strongly believe that given its known attributes, cetrorelix has the potential to successfully penetrate a $4 plus billion market." Herbert Lepor, M.D., Professor and Martin Spatz Chairman of Urology at the NYU School of Medicine and Lead Investigator of the Phase 3 program added, "Having been involved in BPH research for more than 20 years and considering the strong prior data on cetrorelix, I am pleased that the Phase 3 program for cetrorelix is advancing on course and thrilled to continue my involvement with this novel compound leading its class in development. I believe cetrorelix has a high probability of ultimately providing a convenient, safe and effective treatment for the millions of men suffering from BPH. " This first study, involving approximately 600 patients, is part of an extensive Phase 3 program enrolling a total of about 1,500 patients, which will include other large safety and efficacy studies conducted in North America and Europe. The trial is open for patient recruitment. If interested in more information about the trial, please visit http://www.clinicaltrials.gov/. The Identifier for this trial is NCT00449150. About the Phase 3 Program with Cetrorelix in BPH In the first multi-center study, patients enter a 4-week run-in no-treatment observation period to confirm severity and stability of voiding symptoms based on the International Prostate Symptom Score (IPSS). Patients are then allocated to cetrorelix in a double-blind, randomized, double-dummy, placebo-controlled fashion. Patients are administered an intra-muscular (IM) injection of cetrorelix at Week 0, 2, 26 and 28 and are followed up to Week 52. Then, in an open-label fashion, patients are administered an IM injection of cetrorelix at Week 52, 54, 78 and 80 and are followed up to Week 90. The primary efficacy endpoint of this first study is absolute change in IPSS between baseline before beginning treatment and Week 52, while safety endpoints include changes in sexual function as well as BPH symptom progression equal to or more than 4 points and/or acute urinary retention and/or need for BPH related surgery. Other important endpoints consist of plasma levels of testosterone and changes in bone mineral density. This first study is being conducted across the United States and Canada and involves approximately 600 patients under the supervision of lead investigator, Herbert Lepor, M.D., Professor at NY University School of Medicine, New York. Dr. Lepor was the lead investigator for a prior Phase 2 trial with cetrorelix in BPH. The second multi-center study of this Phase 3 program is expected to be initiated in the second half of 2007 and will enroll approximately 300 patients in Europe. Patients will receive cetrorelix according to similar administration regimens used in the first study. The third multi-center study of this Phase 3 program, which is expected to be initiated in the second half of 2007, will be an open-label, single-armed safety study involving approximately 600 patients in both North America and Europe. About Benign Prostatic Hyperplasia BPH is characterized by an abnormal benign growth of the prostatic tissues caused by testosterone. Symptoms linked to BPH include pain while urinating and frequent urges to urinate during the night and sometimes, kidney problems. In some cases, if left untreated, BPH may develop into prostate cancer. BPH affects more than 50% of men 60 years and over, with approximately 56 million cases in the U.S., Europe and Japan. As of 2004, BPH treatment represented a market size of over $2.6 billion. Contrary to most of the present treatments for BPH, cetrorelix is not associated with side-effects such as erectile dysfunction, loss of libido and chemical castration. According to Decision Resource, cetrorelix is currently the most advanced LHRH-antagonist in development for the treatment of BPH. About Cetrorelix Cetrorelix is part of AEterna Zentaris' LHRH antagonist therapeutic approach. This peptide-based active substance was developed by the Company in cooperation with Nobel Prize winner Professor Andrew Schally of the U.S. Veterans Administration in Miami. Cetrorelix is marketed under the brand name Cetrotide(R), the first LHRH antagonist approved for therapeutic use as part of in vitro fertilization programs (controlled ovulation stimulation/assisted reproductive technologies) in Europe, the USA and Japan. It was launched on the market through Merck Serono in the U.S., Europe and in several other countries, as well as in Japan through Shionogi. In addition to the Phase 3 program in BPH, cetrorelix is also in a Phase 2 program in this same indication in Japan, sponsored by the Company's partner, Shionogi as well as in a clinical program for endometriosis sponsored by Solvay. About AEterna Zentaris Inc. AEterna Zentaris Inc. is a global biopharmaceutical company focused on endocrine therapy and oncology, with proven expertise in drug discovery, development and commercialization. News releases and additional information are available at http://www.aeternazentaris.com/. Forward-Looking Statements This press release contains forward-looking statements made pursuant to the safe harbor provisions of the U.S. Securities Litigation Reform Act of 1995. Forward-looking statements involve known and unknown risks and uncertainties, which could cause the Company's actual results to differ materially from those in the forward-looking statements. Such risks and uncertainties include, among others, the availability of funds and resources to pursue R&D projects, the successful and timely completion of clinical studies, the ability of the Company to take advantage of business opportunities in the pharmaceutical industry, uncertainties related to the regulatory process and general changes in economic conditions. Investors should consult the Company's quarterly and annual filings with the Canadian and U.S. securities commissions for additional information on risks and uncertainties relating to the forward-looking statements. Investors are cautioned not to rely on these forward-looking statements. The Company does not undertake to update these forward-looking statements. DATASOURCE: AETERNA ZENTARIS INC. CONTACT: Jenene Thomas, Senior Director, Investor Relations & Corporate Communications, (418) 655-6420, ; Paul Burroughs, Media Relations, (418) 652-8525 ext. 406,

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