Æterna Zentaris Announces Perifosine Receives FDA Fast Track Designation for
the Treatment of Refractory Advanced Colorectal Cancer

QUEBEC CITY, April 5 /CNW Telbec/ - Æterna Zentaris Inc. (NASDAQ: AEZS, TSX: AEZ) (the "Company"), a late-stage drug development company specialized in oncology and endocrine therapy, today announced that its partner, Keryx Biopharmaceuticals (Nasdaq: KERX), was granted Fast Track designation by the U.S. Food and Drug Administration ("FDA") for perifosine (KRX-0401), the Company's novel, potentially first-in-class, oral anti-cancer agent that inhibits the phosphoinositide 3-kinase (PI3K)/Akt pathway, for the treatment of refractory advanced colorectal cancer. Keryx is Æterna Zentaris' partner and licensee for perifosine in the United States, Canada and Mexico. Æterna Zentaris has also out-licensed perifosine to Handok in South Korea while retaining rights for the rest of the world.

The Fast Track program of the FDA is designed to facilitate the development and expedite the review of new drugs that are intended to treat serious or life-threatening conditions and that demonstrate the potential to address unmet medical needs. Fast Track designated drugs ordinarily qualify for priority review, thereby expediting the FDA review process.

A randomized, double-blind Phase 3 trial investigating perifosine in combination with capecitabine (Xeloda(R)) versus placebo in combination with capecitabine (Xeloda(R)) in patients with refractory metastatic colorectal cancer is expected to commence this quarter under a Special Protocol Assessment (SPA) with the FDA.

Juergen Engel, Ph.D., President and Chief Executive Officer of Æterna Zentaris, commented, "We now look forward to the initiation and sponsorship by our partner, Keryx, of this key registration Phase 3 trial in refractory metastatic colorectal cancer in North America which they expect to complete in 2011, with product launch, in the USA, in 2012. These data will be very supportive of our efforts to register perifosine in the rest of the world, and in some countries, we expect they will be sufficient to do so without any additional studies."

In addition to colorectal cancer, perifosine is currently in a Phase 3 trial, under a SPA, for the treatment of relapsed/refractory multiple myeloma, with Orphan Drug Status and Fast Track Designation granted. This trial is also sponsored by our partner, Keryx.

Furthermore, the Company received a positive opinion for Orphan Medicinal Product Designation for perifosine from the Committee for Orphan Medicinal Products (COMP) of the European Medicines Agency for the treatment of multiple myeloma.

About Perifosine

Perifosine is a novel, potentially first-in-class, oral anti-cancer agent that modulates Akt, and a number of other key signal transduction pathways, including the JNK and MAPK pathways, all of which are pathways associated with programmed cell death, cell growth, cell differentiation and cell survival. The effects of perifosine on Akt are of particular interest because of the importance of this pathway in the development of most cancers, with evidence that it is often activated in tumors that are resistant to other forms of anticancer therapy, and the difficulty encountered thus far in the discovery of drugs that will inhibit this pathway without causing excessive toxicity. High levels of activated Akt (pAkt) are seen frequently in many types of cancer and have been correlated with poor prognosis.

About Colorectal Cancer

According to the American Cancer Society, colorectal cancer is the third most common form of cancer diagnosed in the United States. It is estimated that over 146,000 people were diagnosed with some form of colorectal cancer with over 49,000 patients dying from colorectal cancer in 2009. Surgery is often the main treatment for early stage colorectal cancer. When colorectal cancer metastasizes (spreads to other parts of the body such as the liver) chemotherapy is commonly used. Treatment of patients with recurrent or advanced colorectal cancer depends on the location of the disease. Chemotherapy regimens (i.e. FOLFOX or FOLFIRI either with or without bevacizumab) have been shown to increase survival rates in patients with metastatic/advanced colorectal cancer. Currently, there are seven approved drugs for patients with metastatic colorectal cancer: 5-fluorouracil (5-FU), capecitabine (Xeloda(R)), irinotecan (Camptosar(R)), oxaliplatin (Eloxatin(R)), bevacizumab (Avastin(R)), cetuximab (Erbitux(R)), and panitumumab (Vectibix(R)). Depending on the stage of the cancer, two or more of these types of treatment may be combined at the same time or used after one another. For example, FOLFOX combines 5-FU, leucovorin and oxaliplatin and FOLFIRI combines 5-FU, leucovorin and irinotecan. Bevacizumab, a VEGF monoclonal antibody, is commonly administered with chemotherapy. Typically, patients who fail 5-FU, oxaliplatin, irinotecan, and bevacizumab-containing therapies, and who have wild-type KRAS status receive EGFR monoclonal antibody therapy with either cetuximab or panitumumab. Once patients progress on these agents, there are no further standard treatment options.

About Æterna Zentaris Inc.

Æterna Zentaris Inc. is a late-stage drug development company specialized in oncology and endocrine therapy. News releases and additional information are available at www.aezsinc.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. We disclaim any obligation to update any such factors or to publicly announce the result of any revisions to any of the forward-looking statements contained herein to reflect future results, events or developments except if we are required by a governmental authority or applicable law.

For further information: Investor Relations: Ginette Vallières, Investor Relations Coordinator, [phone], ext. 265, [email protected]; Media Relations: Paul Burroughs, Director of Communications, [phone], ext. 406, [email protected]