July 27, 2011

Aeterna Zentaris Announces Completion of Patient Recruitment for Phase 3 Trial with Perifosine in Refractory Advanced Colorectal Cancer

QUEBEC CITY, July 27, 2011 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:
AEZS) (TSX: AEZ) (the "Company") today announced the completion of
patient recruitment for the ongoing Phase 3 trial with perifosine in
refractory advanced colorectal cancer. The trial, involving over 430
patients, is being conducted pursuant to a Special Protocol Assessment
(SPA) with the Food and Drug Administration (FDA) and with Fast Track
Designation. It is sponsored by Keryx Biopharmaceuticals, Inc.,
(Keryx), (NASDAQ: KERX), Aeterna Zentaris' licensee for perifosine in
North America. Perifosine is a novel, potentially first-in-class, oral
anticancer drug candidate that inhibits Akt activation in the
phosphoinositide 3-kinase (PI3K) pathway.

Juergen Engel, Ph.D., Aeterna Zentaris President and Chief Executive
Officer, commented, "We wish to congratulate our partner Keryx and
thank all those involved in reaching this key patient recruitment
milestone within a 16-month timeframe. We now look forward to the
completion of this pivotal Phase 3 trial in order to potentially
provide an additional treatment to refractory advanced colorectal
cancer patients."

Phase 3 Trial Design

The Phase 3 trial, entitled the "X-PECT" (Xeloda(®) + Perifosine Evaluation in Colorectal cancer Treatment) trial, is a randomized (1:1), double-blind trial comparing the
efficacy and safety of perifosine + capecitabine vs. placebo +
capecitabine in over 430 patients with refractory advanced colorectal
cancer. Patients must have failed available therapy including
5-fluorouracil (5-FU), oxaliplatin (Eloxatin(®)), irinotecan, bevacizumab (Avastin(®)) and, if KRAS wild-type, failed prior therapy with cetuximab (Erbitux(®)) and/or panitumumab (Vectibix(®)). The primary endpoint is overall survival, with secondary endpoints
including overall response rate (complete + partial responses),
progression-free survival and safety. Approximately 360 events of death
will trigger the un-blinding of the study.

Dr. Johanna Bendell, Director of GI Oncology Research for the Sarah
Cannon Research Institute, Nashville, Tennessee, is Study Chair for the
Phase 3 investigational team. Dr. Cathy Eng, Associate Medical Director
for the Colorectal Center at MD Anderson Cancer Center in Houston,
Texas, is the Lab Correlative Study Chair leading the biomarker
analyses. Sixty-five U.S. sites are participating in the study.

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 141,000 people will be diagnosed with some form of
colorectal cancer with over 49,000 patients dying from colorectal
cancer in 2011. 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 advanced colorectal
cancer. Currently, there are seven approved drugs for patients with
advanced colorectal cancer: 5-fluorouracil (5-FU), capecitabine (Xeloda(®)), irinotecan, oxaliplatin (Eloxatin(®)), bevacizumab (Avastin(®)), cetuximab (Erbitux(®)), and panitumumab (Vectibix(®)). 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 Perifosine

Perifosine is a novel, oral anticancer treatment that inhibits Akt
activation in the phosphoinositide 3-kinase (PI3K) pathway. The product
works by interfering with membranes of cancer cells thereby inhibiting
Akt signaling which then affects cell death, growth, differentiation
and survival. Perifosine, in combination with chemotherapeutic agents,
is currently being studied for the treatment of multiple myeloma,
colorectal cancer and other cancers, and is the most advanced
anticancer agent of its class. Perifosine, as monotherapy, is being
explored in other indications. The FDA has granted perifosine
orphan-drug designation in multiple myeloma and neuroblastoma, and Fast
Track designations in both multiple myeloma and refractory advanced
colorectal cancer. Additionally, an agreement was reached with the FDA
to conduct the Phase 3 trials in both of these indications under a
Special Protocol Assessment. Perifosine has also been granted orphan
medicinal product designation from the European Medicines Agency (EMA)
in multiple myeloma. Furthermore, perifosine has received positive
Scientific Advice from the EMA for both the multiple myeloma and
advanced colorectal cancer programs, with ongoing Phase 3 trials for
these indications expected to be sufficient for registration in Europe.
Perifosine rights have been licensed to Keryx for North America, to
Yakult Honsha for Japan and to Handok for Korea.

About Aeterna Zentaris Inc.

Aeterna Zentaris is a late-stage oncology drug development company
currently investigating potential treatments for various cancers
including colorectal, multiple myeloma, endometrial, ovarian, prostate
and bladder cancer. The Company's innovative approach of "personalized
medicine" means tailoring treatments to a patient's specific condition
and to unmet medical needs. Aeterna Zentaris' deep pipeline is drawn
from its proprietary discovery unit providing the Company with constant
and long-term access to state-of-the-art therapeutic options. For more
information please visit www.aezsinc.com.

Forward-Looking Statements

This press release contains forward-looking statements made pursuant to
the safe harbour provisions of the U.S. Securities Litigation Reform
Act of 1995. Forward-looking statements involve known and unknown risks
and uncertainties that 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
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, unless required to do
so by a governmental authority or by applicable law.