SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    --------

                                    FORM 6-K

                        REPORT OF FOREIGN PRIVATE ISSUER
                      PURSUANT TO RULE 13a-16 OR 15d-16 OF
                       THE SECURITIES EXCHANGE ACT OF 1934

                         For the month of October, 2005

                                   Serono S.A.
                ------------------------------------------------
                               (Registrant's Name)

                            15 bis, Chemin des Mines
                                 Case Postale 54
                                CH-1211 Geneva 20
                                   Switzerland
                    ----------------------------------------
                    (Address of Principal Executive Offices)

                                     1-15096
                ------------------------------------------------
                              (Commission File No.)

     (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   X    Form 40-F
               -----            -----

     (Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(1).)
                                                        -----

     (Indicate by check mark if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(7).)
                                                        -----

     (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-      )
                                                 ------



CancerVax(TM)                                                             Serono


Media Release


FOR IMMEDIATE RELEASE
---------------------


                   DATA AND SAFETY MONITORING BOARD RECOMMENDS
             DISCONTINUATION OF CANVAXIN(TM) PHASE 3 CLINICAL TRIAL
                      FOR PATIENTS WITH STAGE III MELANOMA

GENEVA,  SWITZERLAND  AND  CARLSBAD,  CALIFORNIA, USA - OCTOBER 3, 2005 - Serono
(virt-x:  SEO  and  NYSE: SRA) and CancerVax Corporation (NASDAQ:CNVX) announced
today  their  decision to discontinue the Phase 3 clinical trial of Canvaxin(TM)
in  patients  with  Stage  III  melanoma  based  upon  the recommendation of the
independent  Data  and  Safety Monitoring Board (DSMB), which recently completed
its planned, third, interim analysis of the data from this study. The DSMB found
that  the  data  are  unlikely  to  provide  significant  evidence of an overall
survival  benefit  for  patients  with  Stage III melanoma who were treated with
Canvaxin(TM)  versus  those  who  received  placebo.

"This  news  is particularly disappointing because we understand the devastating
impact  of  this  disease  on  patients with advanced-stage melanoma, as well as
their  families and friends. We are extremely grateful for the strong support we
have  received  for  this  clinical  trial  from  the  clinicians, nurses, study
coordinators  and,  especially,  the  patients who participated in this clinical
trial," said David F. Hale, President and CEO of CancerVax Corporation. "We will
discontinue  all  further  development  and  manufacturing  operations  for
Canvaxin(TM),  but  we  currently plan to continue to further the development of
the  other  product  candidates  in  our product pipeline, which we believe hold
promise  for  the  treatment  of  patients  with  cancer."

"The  Phase  2 results were promising, and we were thus hopeful that this highly
innovative  product  would be successful in a Phase 3 clinical trial in patients
with Stage III melanoma," said Franck Latrille, Senior Executive Vice President,
Corporate  Global  Product  Development of Serono. "We continue to have a strong
pipeline  with  five  Phase  3 programs and significant newsflow expected in the
next year. Serono remains committed to oncology with Humax-CD4, adecatumumab and
TACI-Ig  with  study  results  from  all  three  programs  expected  in  2006."

There  were  no  significant  safety  issues  identified with either the Phase 3
clinical  trial of Canvaxin(TM) in patients with Stage III melanoma, or with the
Phase 3 clinical trial of Canvaxin(TM) in patients with Stage IV melanoma, which
was  discontinued  earlier this year. The recommendations to close both of these
clinical trials were not made because of any potential safety concerns. Once the
data  from  these  clinical trials are fully analyzed, they will be presented at
appropriate  scientific  meetings.


                                                                               1

ABOUT  THE  DSMB  AND  INTERIM  ANALYSES
The  DSMB  consists  of  independent  experts  in medical and surgical oncology,
statistics  and medical ethics who are not participating in the clinical trials,
whose  primary  responsibility  is  to  monitor,  on  a periodic basis, the data
emerging  from a clinical trial and to provide recommendations to the sponsor on
whether  a  study  should  be  modified  or  discontinued.

ABOUT  SERONO
Serono  is  a  global  biotechnology leader. The Company has eight biotechnology
products,  Rebif(R),  Gonal-f(R),  Luveris(R),  Ovidrel(R)/Ovitrelle(R),
Serostim(R),  Saizen(R),  Zorbtive(TM)  and Raptiva(R). In addition to being the
world  leader  in  reproductive  health,  Serono  has strong market positions in
neurology,  metabolism  and  growth and has recently entered the psoriasis area.
The  Company's  research programs are focused on growing these businesses and on
establishing  new  therapeutic  areas,  including oncology. Currently, there are
approximately  30  ongoing  development  projects.

In  2004,  Serono  achieved  worldwide revenues of US$2,458.1 million, and a net
income  of  US$494.2 million, making it the third largest biotech company in the
world.  Its  products  are  sold  in over 90 countries.  Bearer shares of Serono
S.A.,  the  holding  company,  are  traded  on the virt-x (SEO) and its American
Depositary  Shares  are  traded  on  the  New  York  Stock  Exchange  (SRA).

ABOUT  CANCERVAX  CORPORATION  (WWW.CANCERVAX.COM)
                                -----------------
CancerVax  Corporation  is  a  biotechnology  company  focused  on the research,
development and commercialization of novel biological products for the treatment
and  control  of cancer. CancerVax has been evaluating Canvaxin(TM) in a Phase 3
clinical  trial  for  the  treatment  of  patients  with  Stage  III melanoma in
collaboration  with  Serono. CancerVax also has a pipeline of product candidates
and technologies that are being developed for the potential treatment of cancer.
These  include  SAI-EGF,  a  product candidate that targets the epidermal growth
factor  (EGF)  receptor  signaling  pathway;  and  D93,  CancerVax's  lead
anti-angiogenic  humanized  monoclonal  antibody.  CancerVax  plans  to  file an
Investigational  New  Drug (IND) application for clinical trials of D93 in early
2006,  and  to  initiate a clinical trial with SAI-EGF in patients with advanced
non-small-cell  lung  cancer  in  2006.

CANCERVAX  CORPORATION
CONFERENCE  CALL  AND  WEBCAST  TUESDAY,  OCTOBER  4,  AT  9:00  EASTERN  TIME
CancerVax  management will host a conference call on Tuesday, October 4, at 9:00
a.m. Eastern Time to discuss the DSMB recommendation to discontinue the Canvaxin
Phase  3  clinical  trial  for  patients  with  Stage III melanoma. A live audio
webcast  of  management's  presentation  will  be  available  at
http://ir.cancervax.com.  Alternatively,  callers  may  participate  in  the
conference  call  by  dialing  (866)  831-6270  (domestic)  or  (617)  213-8858
(international).  The  passcode is 70660579. A replay of the conference call can
be  accessed  by  dialing  (888)  286-8010  (domestic)  or  (617)  801-6888
(international).  The passcode for the replay is 42654318. The webcast will also
be  archived  on  CancerVax's  website.

                                       ###
FORWARD-LOOKING STATEMENTS
--------------------------

SERONO
Some  of  the  statements  in  this  press  release  are  forward  looking. Such
statements  are inherently subject to known and unknown risks, uncertainties and
other  factors  that  may  cause  actual results, performance or achievements of
Serono  S.A.  and  affiliates  to be materially different from those expected or
anticipated  in  the  forward-looking statements. Forward-looking statements are
based on Serono's current expectations and assumptions, which may be affected by
a  number  of  factors, including those discussed in this press release and more
fully  described  in  Serono's  Annual  Report  on Form 20-F filed with the U.S.
Securities  and Exchange Commission on March 16, 2005. These factors include any
failure  or  delay  in  Serono's ability to develop new products, any failure to
receive  anticipated  regulatory  approvals,  any  problems  in  commercializing
current  products  as  a  result of competition or other factors, our ability to
obtain  reimbursement  coverage  for  our  products,  the  outcome of government
investigations and litigation and government regulations limiting our ability to
sell  our  products.  Serono has no responsibility to update the forward-looking
statements  contained  in  this press release to reflect events or circumstances
occurring  after  the  date  of  this  press  release.


                                                                               2

                                       ###

CANCERVAX  CORPORATION
CancerVax  cautions  you that statements included in this press release that are
not  a  description  of  historical  facts  are  forward-looking statements. For
example,  statements  about the timing of the initiation of clinical trials with
any  of  CancerVax's product candidates, and plans and objectives of management,
are  all forward-looking statements. The inclusion of forward-looking statements
should  not  be  regarded as a representation by CancerVax that any of its plans
will  be  achieved. Actual results may differ materially from those set forth in
this release due to the risks and uncertainties inherent in CancerVax's business
including,  without limitation: the progress, timing and outcome of its clinical
trials;  its  ability  to obtain additional financing to support its operations,
which  could  adversely  affect  its  ability  to continue to operate as a going
concern;  the  risk  that  the  collaboration  agreement for Canvaxin(TM) may be
terminated  by  Serono  in  certain  instances;  the  risk that CancerVax may be
required to pre-pay the debt incurred to expand its manufacturing capacity prior
to  the  termination  of  the loan because of a failure to comply with covenants
included  in  the  loan agreement; unexpected adverse side effects or inadequate
therapeutic  efficacy  of  its  product  candidates  that could delay or prevent
product  development  or  commercialization,  or that could result in recalls or
product liability claims; competition from other pharmaceutical or biotechnology
companies;  CancerVax's  limited  experience  in  manufacturing  and  testing
biological  products,  which  may  result  in  delayed  development  or
commercialization  of its product candidates, as well as lost revenue; and other
risks  detailed  in  CancerVax's  Securities  and  Exchange  Commission filings,
including  CancerVax's  Annual  Report  on  Form  10-K for the fiscal year ended
December  31,  2004,  and Quarterly Report for the fiscal quarter ended June 30,
2005.  You  are  cautioned  not to place undue reliance on these forward-looking
statements,  which  speak  only  as  of  the  date  hereof.  All forward-looking
statements  are  qualified  in  their  entirety by this cautionary statement and
CancerVax  undertakes  no  obligation  to  revise or update this news release to
reflect  events  or  circumstances  after  the date hereof. This caution is made
under the safe harbor provisions of the Private Securities Litigation Reform Act
of  1995.

                                       ###

CancerVax(R) is a registered trademark of CancerVax Corporation.
Canvaxin(TM) is a trademark of CancerVax Corporation.


FOR  MORE  INFORMATION,  PLEASE  CONTACT:

SERONO



                           
  CORPORATE MEDIA RELATIONS:  CORPORATE INVESTOR RELATIONS:
  Tel:  +41 22 739 36 00      Tel:  +41 22 739 36 01
  Fax:  +41 22 739 30 85      Fax:  +41 22 739 30 22
  http://www.serono.com       Reuters: SEO.VX / SRA.N
  ---------------------       Bloomberg: SEO VX / SRA US

  MEDIA RELATIONS, USA:       INVESTOR RELATIONS, USA:
  Tel:  +1 781 681 2340       Tel:  +1 781 681 2552
  Fax:  +1 781 681 2935       Fax:  +1 781 681 2912
  http://www.seronousa.com
  ------------------------


CANCERVAX CONTACT:
William R. La Rue
CancerVax Corporation
Chief Financial Officer
+1 760-494-4200
http://www.cancervax.com
------------------------



                                                                               3

                                   SIGNATURES

     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.



                                            SERONO S.A.
                                            a Swiss corporation
                                            (Registrant)



October 3, 2005                             By:     /s/ Stuart Grant
                                                    ----------------------------
                                            Name:   Stuart Grant
                                            Title:  Chief Financial Officer