QUÉBEC CITY, June 3, 2013 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ: AEZS) (TSX: AEZ) (the "Company") today announced that final data for the Phase 1 portion of the ongoing Phase 1/2 trial with its lead oncology compound, zoptarelin doxorubicin (AEZS-108), demonstrated the compound's promising anti-tumor activity in heavily pre-treated men with castration- and taxane-resistant prostate cancer. Results were presented earlier today by lead investigator, Jacek Pinski, MD, PhD, of the USC Norris Comprehensive Cancer Center, during a poster session at the American Society of Clinical Oncology's ("ASCO") Annual Meeting in San Francisco. David Dodd, President and CEO of Aeterna Zentaris stated, "We are encouraged with the Phase 1 portion data and look forward to further results from the current Phase 2 portion of this investigator-driven trial. Because luteinizing hormone-releasing hormone receptors are expressed in a great number of prostate cancers, we believe that zoptarelin doxorubicin (AEZS-108), which specifically targets those receptors, may represent a novel targeted treatment for men with this disease. Expansion into prostate, breast and bladder cancer with zoptarelin doxorubicin (AEZS-108) after positive Phase 2 results in endometrial and ovarian cancer, is further demonstration of the potential of this innovative compound in a variety of cancer indications for both men and women." Methods This was a dose-escalation Phase 1 trial in men with castration- and taxane-resistant prostate cancer to confirm the dose established in a Phase 1 trial in women. Patients received zoptarelin doxorubicin (AEZS-108) every 21 days until progression or unacceptable toxicity. The primary endpoint was safety. Circulating Tumor Cells ("CTC") were captured with a novel slot microfilter and identified by PSA and DAPI staining. AEZS-108 internalization was visualized by fluorescence microscopy. Results Eighteen men with a median of 2 prior chemotherapy regimens (range 1-5) and a median PSA of 106.4 ng/mL (range 8.4-1624.0) were enrolled. The dose of zoptarelin doxorubicin (AEZS-108) was escalated from 160 mg/m 2 to 210 mg/m 2 then to 267 mg/m 2. There were 2 Dose-Limiting Toxicities ("DLT") in the 7 patients receiving zoptarelin doxorubicin (AEZS-108) at a dose of 267 mg/m 2 (grade 4 neutropenia and grade 3 febrile neutropenia), prompting de-escalation to 210 mg/m 2, where 1 of 8 patients experienced a DLT (grade 4 neutropenia), establishing 210 mg/m 2 as the Maximum Tolerated Dose ("MTD"). Significant non-hematologic toxicities included one case of grade 3 nausea. No cardiotoxicity was seen on serial evaluation and 6 patients completed 6 cycles. Internalization of zoptarelin doxorubicin (AEZS-108) was consistently visualized in CTCs 1 to 3 hours after dosing. Maximal PSA response was stable or decreased in 8 of 18 men. Conclusion In general, zoptarelin doxorubicin (AEZS-108) was well tolerated and demonstrated promising evidence of its anti-tumor activity in this heavily pretreated population with castration- and taxane-resistant prostate cancer. Among the 15 evaluable patients with measurable disease, 10 achieved stable disease and a drop in PSA was noted in 3 patients. The MTD of zoptarelin doxorubicin (AEZS-108) in this indication is 210 mg/m 2, which is below the MTD reported in women with refractory endometrial and ovarian cancer. The poster entitled, "A Phase I Dose-Escalation Trial of AEZS-108 in Castration- and Taxane-Resistant Prostate Cancer", is available on ASCO's website at the following link. Current Phase 2 Portion of the Study This is a single-arm Simon Optimum design Phase 2 study of zoptarelin doxorubicin (AEZS-108) involving up to 37 patients with pre-treated castration-and taxane-resistant prostate cancer, using the dose selected (210 mg/m 2) in the Phase 1 portion. The primary endpoint is to evaluate the clinical benefit of zoptarelin doxorubicin (AEZS-108) for these patients. Clinical benefit will be defined as non-progression at 12 weeks with no dose-limiting toxicity or other toxicity requiring termination of treatment. More information on the current Phase 2 portion of the trial is available at this link NCT01240629. About zoptarelin doxorubicin (AEZS-108) Zoptarelin doxorubicin (AEZS-108) represents a new targeting concept in oncology using a hybrid molecule composed of a synthetic peptide carrier and a well-known chemotherapy agent, doxorubicin. Zoptarelin doxorubicin (AEZS-108) is the first intravenous drug in advanced clinical development that directs the chemotherapy agent specifically to Luteinizing Hormone-Releasing Hormone ("LHRH")-receptor expressing tumors, resulting in more targeted treatment with less damage to healthy tissue. The product has successfully completed Phase 2 studies for the treatment of ovarian and endometrial cancer and the Company is currently initiating a Phase 3 trial in endometrial cancer under a Special Protocol Assessment. Zoptarelin doxorubicin (AEZS-108) is also in Phase 2 trials in triple-negative breast cancer, prostate cancer and bladder cancer. Zoptarelin doxorubicin (AEZS-108) has been granted orphan drug designation by the FDA and orphan medicinal product designation from the European Medicines Agency for the treatment of ovarian cancer. Aeterna Zentaris owns worldwide rights to zoptarelin doxorubicin.