Æterna Zentaris’ LHRH-Receptor Targeted Therapy AEZS-108 Produces Positive Preliminary Results in Advanced Stage Ovarian Cancer

Preliminary Phase II clinical study evaluation shows that primary efficacy endpoint has been met for patients with advanced-stage, platinum-resistant, taxane-pretreated ovarian cancer who were treated with the targeted therapy AEZS-108.

Æterna Zentaris Inc. , a global biopharmaceutical company focused on endocrine therapy and oncology, today announced positive efficacy data from a Phase II study with its targeted therapy AEZS-108 (formerly AN-152 or ZEN-008), in patients with platinumresistant, taxane-pretreated ovarian cancer. In a personalized healthcare approach, the study selected patients with tumors expressing luteinizing hormone-releasing hormone (LHRH) receptors, the key element in the targeting mechanism of AEZS-108. Under coordination by Prof. Günter Emons, MD, Chairman of the Department of Obstetrics & Gynaecology at the University of Göttingen, Germany, this open-label, multi-center and multi-national Phase II study (AGO-GYN 5) is being conducted by the German AGO Study Group (Arbeitsgemeinschaft Gynäkologische Onkologie / Gynaecological Oncology Working Group; www.ago-ovar.de), in cooperation with clinical sites in Europe.

Preliminary Phase II Clinical Study Results

Juergen Engel, Ph.D., President & CEO, AEterna Zentaris

Juergen Engel, Ph.D., President & Chief Executive Officer, Æterna Zentaris Inc. (Photo: AEterna Zentaris Inc.)

All 43 patients with LHRH-receptor positive ovarian cancer who entered study AGO-GYN 5 have completed their study treatment. A preliminary evaluation shows that the study met its primary efficacy endpoint of 5 or more responders in 41 evaluable patients.

Responders, as well as patients with stable disease after completion of treatment with AEZS 108, will now be followed to assess the duration of progression-free survival and, ultimately, overall survival. More detailed analyses, which will also include efficacy data from post-treatment follow-up of the ovarian cancer patients, are currently in preparation and will be presented at forthcoming scientific conferences.

Juergen Engel, Ph.D., Æterna Zentaris President and Chief Executive Officer stated, “We are pleased with the progress of this project. The successful completion of the recruitment and treatment phase and the apparent activity in this difficult group of cancer patients is encouraging. This is the basis we were looking for, in order to take the next steps in the further development of AEZS 108 in gynecological cancers and possibly also in prostate cancer.”

About the AEZS-108 Phase II Clinical Study

AEZS-108 represents a new targeting concept in oncology using a cytotoxic peptide conjugate which is a hybrid molecule composed of a synthetic peptide carrier and a well-known cytotoxic agent, doxorubicin. The design of this product allows for the specific binding and selective uptake of the cytotoxic conjugate by LHRH-receptor-positive tumors. The binding of AEZS-108 to cancerous cells that express these receptors results in its accumulation and preferential uptake in the malignant tissue.

In a Phase II study program entitled, “The antitumoral activity and safety of AEZS 108 (AN 152), a LHRH agonist linked doxorubicin in women with LHRH-receptor positive gynecological tumors“, patients with tumors expressing LHRH receptors are administered an intravenous infusion of 267 mg/m2 of AEZS 108 over a period of 2 hours, every Day 1 of a 21-day (3-week) cycle. The proposed duration of the study treatment is 6, 3-week cycles. Study AGO GYN 5 is performed with 14 centers of the German Gynecological Oncology Working Group (AGO; www.ago-ovar.de), in cooperation with 3 clinical sites in Europe.

The program was designed to include up to 82 patients; approximately 41 with a diagnosis of platinum-resistant, taxane-pretreated ovarian cancer, and 41 with disseminated endometrial cancer. For both indications, patient recruitment was planned in 2 stages with 21 and 20 patients, respectively, and the primary efficacy endpoint at the end of stage 2 was defined as 5 or more patients with partial or complete tumor responses according to Response Evaluation Criteria in Solid Tumors (RECIST) and/or Gynecologic Cancer Intergroup (GCIG) guidelines. Secondary endpoints include time to progression, survival, toxicity, as well as adverse effects.

Prior Phase I Clinical Trial Results

On June 3, 2007 positive results of an open, multi-center, sequential group, dose-escalation Phase I study in various gynecological cancers were presented at the American Society of Clinical Oncology’s (ASCO) Annual Meeting in Chicago, Illinois. Seventeen (17) patients with LHRH-receptor positive gynecological cancers were recruited. AEZS-108 was administered by intravenous infusion over two hours at dosages of 10, 20, 40, 80,160 and 267 mg/m2. At 160 mg/m2, six patients had a total of 32 cycles and at 267 mg/m2, seven patients had a total of 27 cycles. Most of the patients had been pretreated with various chemotherapies.

The study showed that AEZS-108 was well tolerated by patients with gynecological tumors. Furthermore, AEZS-108 is the first drug in a clinical study that targets the cytotoxic activity of doxorubicin specifically to LHRH-receptor expressing tumors. Finally, signs of anti-tumor activity were observed in seven out of 13 patients treated with 160 or 267 mg/m2 of AEZS 108, including three patients with complete or partial response

About AEZS-108

AEZS-108 Mechanism of Action

AEZS-108 Mechanism of Action (Photo: AEterna Zentaris Inc.)

AEZS-108 is a targeted cytotoxic peptide conjugate which is a hybrid molecule composed of a synthetic peptide carrier and a well-known cytotoxic agent, doxorubicin. The design of this product allows for the specific binding and selective uptake of the cytotoxic conjugate by LHRH-receptor-positive tumors. The binding of AEZS-108 to cancerous cells that express these receptors results in its accumulation in the malignant tissue. This binding is followed by internalization and retention of the cytotoxic drug, doxorubicin, in the cells. Therefore, since they target specific cells, cytotoxic conjugates are postulated to be less toxic, have less side-effects and are more effective in vivo than the respective non-conjugated/non-linked cytotoxic agents in inhibiting tumor growth.

About Ovarian and Endometrial Cancer

Ovarian cancer is one of the most common gynecologic malignancies and the fifth most frequent cause of cancer death in women, with most of the cases occurring in women between 50 and 75 years of age. Overall, ovarian cancer accounts for 4% of all cancer diagnoses in women and 5% of all cancer deaths. Approximately 26,000 new cases and 17,000 deaths from this disease are estimated in the European community every year (Source: Gynecologic Oncology, Volume 92, Issue 3, March 2004, Pages 819-826).

Cancer of the endometrium is the most common gynecologic malignancy and accounts for 6% of all cancers in women. The majority of the cases occur in postmenopausal women, with the largest number of women developing their cancers during their sixth decade. Approximately 38,000 new cases and 9,000 deaths from this disease are estimated annually in Europe (Source: Annals of Oncology 15:1149-1150, 2004).

About Æterna Zentaris Inc.

Æterna 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 www.aezsinc.com.

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