FORM 6-K
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                            REPORT OF FOREIGN ISSUER


                      Pursuant to Rule 13a-16 or 15d-16 of
                       the Securities Exchange Act of 1934


                           For the month of April 2005


                             AETERNA ZENTARIS INC. 

                        1405, boul. du Parc-Technologique
                                 Quebec, Quebec
                                 Canada, G1P 4P5
                    (Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports
under cover of Form 20-F or Form 40-F.

                     Form 20-F        Form 40-F    X  
                               ------           ------

Indicate by check mark whether the registrant by furnishing the information
contained in this Form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934

                          Yes       No   X  
                              -----    -----

If "Yes" is marked, indicate below the file number assigned to the registrant in
connection with Rule 12g3-2(b): 82- 
                                   -----




                                 DOCUMENTS INDEX



DOCUMENTS       DESCRIPTION
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1.              Press release dated April 21, 2005 - AEterna Zentaris Expands Therapeutic
                Approaches in Oncology to Immunotherapeutic Vaccination






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AETERNA ZENTARIS INC. 1405 du Parc-Technologique Blvd.
Quebec (Quebec) Canada  G1P 4P5  T 418 652-8525  F 418 652-0881
www.aeternazentaris.com


                                                           PRESS RELEASE
                                                           For immediate release

AETERNA ZENTARIS EXPANDS THERAPEUTIC APPROACHES IN ONCOLOGY TO IMMUNOTHERAPEUTIC
VACCINATION


QUEBEC CITY, CANADA, APRIL 21, 2005 - AEterna Zentaris Inc. (TSX: AEZ; NASDAQ:
AEZS) today announced that it has established a new research collaboration with
Wurzburg/Germany-based Julius-Maximilians-University on the development of tumor
vaccines based on attenuated bacterial carriers. AEterna Zentaris also acquired
patent rights from the university and the inventors covering several aspects of
both immunotherapeutic approaches against cancer as well as bacterial tumor
targeting. The first expected targets for this research project would be the
development of vaccines against prostate cancer and melanoma.

This vaccine approach exploits the ability of bacteria to induce potent immune
responses and to direct this response against malignancies. The immunogenicity
of the vaccine is further enhanced by the capacity of bacteria to colonize tumor
tissues. This property will be used to transport substances, e.g. proteins, into
the tumor tissue, which are capable of converting non-toxic pro drugs into
active drugs. The preclinical proof of principle has already been shown in a
transgenic animal model and is backed by several patent applications now
transferred to AEterna Zentaris.

The use of bacterial carriers for therapeutic vaccination against tumors and the
concept of bacterial tumor targeting will be further developed with the
Julius-Maximilians-University including the highly recognized researchers Prof.
Dr. Ulf R. Rapp and Prof. Dr. Werner Goebel. Prof. Rapp, Director of the
Institute of Medical Radiology and Cell Research at the
Julius-Maximilians-University, is a known expert in the field of cell and tumor
biology. He is the discoverer of the Raf protein which is one of the key factors
in cancer development. Prof. Goebel, a pioneer in the field of vaccines based on
recombinant bacteria, is Head of the Department of Microbiology. He has
published several groundbreaking works in the field of bacterial virulence
factors.

"Using recombinant bacteria as Trojan horses against malignancies is a very
attractive approach for future cancer therapy. The collaboration with AEterna
Zentaris will allow us to further push ahead in that promising area of
research", said Prof. Rapp.





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"Combining the expertise of high calibre researchers as Prof. Rapp and Prof.
Goebel, their teams and our existing in-house resources, provides AEterna
Zentaris with a unique strength in the area of bacterial tumor therapy", said
Prof. Jurgen Engel, Executive Vice President Global R&D and Chief Operating
Officer at AEterna Zentaris. "The expected close collaboration is yet another
proof of our ability to attract university laboratories and their leading
scientists who are recognized as being at the very forefront of their respective
research area", he added.

Gilles Gagnon, President and Chief Executive Officer at AEterna Zentaris stated:
"Expanding our existing technology platform in oncology beyond small molecules
and cytotoxic conjugates to also cover cancer vaccination, paves the way for
AEterna Zentaris to become a leading biopharmaceutical company in the fight
against cancer. It is our strategic goal to secure a constant flow of innovative
projects in this core area of competence for our Company."

ABOUT IMMUNOTHERAPY

Immunotherapy is a treatment based upon the concept of triggering the body's own
natural defence mechanisms to fight off the disease, usually by stimulating the
immune system either locally or systemically. Oncology represents one of the
most actively researched areas of immunotherapy and offers the promise of new
therapies based upon the idea of stimulating the patient's immune system to
attack the malignant tumor cells that are responsible for the disease.

ABOUT AETERNA ZENTARIS INC.

AEterna Zentaris Inc. is an oncology and endocrine therapy focused
biopharmaceutical company with proven expertise in drug discovery, development
and commercialization. The Company's broad 20 product pipeline leverages five
different therapeutic approaches, including LHRH antagonists and signal
transduction inhibitors. The lead LHRH antagonist compound, cetrorelix, is
currently marketed for IN VITRO fertilization under the brand name Cetrotide(R).
Cetrorelix is also in late-stage clinical development for endometriosis and
benign prostate hyperplasia (BPH). The lead signal transduction inhibitor
compound, perifosine, is an orally-active AKT inhibitor that is in several Phase
II trials for multiple cancers.

AEterna Zentaris owns 50.7% of Atrium Biotechnologies Inc. (ATB.sv), a leading
developer, manufacturer and marketer of value-added products for the cosmetics,
pharmaceutical, chemical and nutritional industries.

News releases and additional information about AEterna Zentaris are available on
its Web site www.aeternazentaris.com.
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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


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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.

                                      -30-

CONTACTS:

MEDIA RELATIONS
Paul Burroughs
(418) 652-8525 ext. 406
paul.burroughs@aeternazentaris.com
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INVESTOR RELATIONS
Ginette Vallieres
(418) 652-8525 ext. 265
ginette.vallieres@aeternazentaris.com
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EUROPE
Matthias Seeber
+49-6942602-3425
matthias.seeber@zentaris.com
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                                    SIGNATURE


             Pursuant to the requirements of the Securities Exchange Act of
1934, the registrant has duly caused this report to be signed on its behalf by
the undersigned, thereunto duly authorized.

                                         AETERNA ZENTARIS INC.


Date:  April 21, 2005                     By:  /s/ Mario Paradis                
---------------------                          ---------------------------------
                                               Mario Paradis
                                               Senior Finance Director and 
                                               Corporate Secretary