Data published at the annual ASCO meeting in Atlanta QUEBEC CITY, Canada, June 5 /PRNewswire-FirstCall/ -- AEterna Zentaris Inc. (TSX: AEZ; NASDAQ: AEZS) today disclosed positive Phase 1 results for its cytotoxic conjugate AN-152 in patients with gynaecological and breast cancers which showed that the compound has a good safety profile and no dose-limiting toxicities. Results were part of an abstract entitled, "Phase I study of AN- 152, a targeted cytotoxic LHRH analog, in female patients with cancers expressing LHRH receptors(x)", published at the 42nd Annual Meeting of the American Society of Clinical Oncology (ASCO), currently being held in Atlanta, Georgia. Dr. Jurgen Engel, Executive Vice President, Global R&D and Chief Operating Officer at AEterna Zentaris, stated, "The pharmacokinetic results provide proof of concept that the chemical linkage of doxorubicin and the luteinizing hormone releasing hormone (LHRH) part of the drug molecule is stable in human blood. This is a prerequisite for the hormone receptor- mediated, specific uptake of the cytotoxic doxorubicin molecule into the targeted tumor cells and at the same time, the minimization of undesired toxic effects to other tissues." Gilles Gagnon, President and Chief Executive Officer at AEterna Zentaris added, "We are very pleased and encouraged with the Phase 1 results for AN- 152. We believe our targeted approach, using patients specifically expressing LHRH receptors, increases our chances of success in these indications. This approach is an additional example of personalized therapy which is becoming more and more the way of the future. We remain committed to aggressively advancing our pipeline and providing novel treatments to those suffering from various types of cancer." Results Eight patients entered the study and received AN-152 by intravenous infusion over two hours at dosages of 10, 20, 40, 80, 160, and 267 mg/m(2). Observation of a grade 2 leukocytopenia in a patient at 160 mg/m(2) led to the addition of three other patients at this dose level. Patients received at least two treatment courses, 21 days apart, and went off study with progressive disease. However, one of the three patients at the dose level of 160 mg/m(2) with a diagnosis of ovarian cancer, showed stabilization of disease and received four treatment courses. Infusion of AN-152 was well tolerated at all dosages, without supportive treatment. Pharmacokinetic (PK) analyses showed dose-dependent plasma levels of AN-152 and only minor (10%- 20%) release of doxorubicin. Conclusions Infusion of AN-152 is well tolerated in female patients. No dose-limiting toxicities were seen up to 267 mg/m(2), which is equimolar to a doxorubicin dose of 77 mg/m(2). Recruitment at this dose level is ongoing. The cytotoxic LHRH analog is stable in human plasma, a prerequisite for receptor-mediated uptake by tumor tissue. Stabilization of disease was observed in one of eight patients in the ongoing Phase 1 study. Background Human breast, endometrial and ovarian cancers commonly express receptors for luteinizing hormone releasing hormone (LHRH-R). LHRH-R can be used for targeted chemotherapy with AN-152, in which doxorubicin is linked to (D- Lys(6))-LHRH. Safety pharmacology and toxicity studies in mice, rats and dogs demonstrated a significantly reduced cardiotoxic potential of AN-152 compared with doxorubicin, e.g. no QT prolongation, myocarditis or fibrosis in the appropriate models. The Phase I study assessed dose-limiting toxicities (DLTs), maximum tolerated dose (MTD), and pharmacokinetics (PK) of AN-152 given once every three weeks in patients with gynaecological and breast cancers. (x)Author Block: G. Emons, M. Kaufmann, A. R. Gunthert, M. Hamid-Werner, C. Grundker, S. Loibl, A. V. Schally; George August University, Goettingen, Germany; J.W. Goethe University, Frankfurt, Germany; V.A. Hospitals, New Orleans / Miami, LA About Cytotoxic Conjugate AN-152 Targeted cytotoxic peptide conjugates are hybrid molecules composed of a synthetic peptide carrier and a well-known cytotoxic product. The design of these products allows for the specific binding and selective uptake of the cytotoxic conjugates by the LHRH receptor-positive tumors. The binding of cytotoxic conjugates to cancerous cells that express these receptors results in an accumulation of the antiproliferative agent in the malignant tissue. This binding is followed by internalisation and retention of the cytotoxic drug in the cells. Therefore, since they target specific cells, cytotoxic conjugates are much less toxic, have less side-effects and are more effective in vivo than the respective radicals in inhibiting tumor growth. AN-152 is currently in a Phase I trial in breast, endometrial and ovarian cancers. About AEterna Zentaris Inc. AEterna Zentaris Inc. is a growing global biopharmaceutical company focused on oncology and endocrine therapy with proven expertise in drug discovery, development and commercialization. AEterna Zentaris also owns 48.29% of the equity of Atrium Biotechnologies Inc. (TSX: ATB.sv) and 64.7% of its voting rights. Atrium is a developer, manufacturer and marketer of science-based products for the cosmetics, pharmaceutical, chemical and nutritional industries. 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. (FORMERLY/ANCIENNEMENT - LES LABORATOIRES AETERNA CONTACT: Media Relations: Paul Burroughs, (418) 652-8525 ext. 406, ; Investor Relations: Jenene Thomas, (418) 655-6420, (908) 996-3154,

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