COMPANY CONTACTS:
Advanced Magnetics, Inc.                  Cytogen Corporation
Jerome Goldstein, CEO                     Michael Becker, CEO
  or Lisa Gordon, Investor Relations        or Stacy Shearer, Investor Relations
 (617) 497-2070                           (609) 750-8289

                FDA ACCEPTS ADVANCED MAGNETICS' COMPLETE RESPONSE
                      TO APPROVABLE LETTER FOR COMBIDEX(R)

CAMBRIDGE, MA, AND PRINCETON, NJ (OCTOBER 19, 2004) -- Advanced Magnetics,  Inc.
(Amex: AVM) and Cytogen Corporation (Nasdaq: CYTO) today announced that Advanced
Magnetics has submitted a complete  response to the approvable  letter  received
from the U.S.  Food and Drug  Administration  (FDA)  for  Combidex(R),  Advanced
Magnetics'  investigational  molecular  imaging  agent.  The  September 30, 2004
submission  has been  accepted  and  assigned  a user fee goal date of March 30,
2005.

COMBIDEX  (ferumoxtran-10)  consists  of  iron  oxide  nanoparticles  for use in
conjunction with magnetic resonance imaging (MRI) to aid in the  differentiation
of cancerous from  non-cancerous  lymph nodes.  Clinical studies have shown that
COMBIDEX  accumulates in  non-cancerous  lymph node tissue which enables doctors
using  magnetic  resonance  imaging to have  improved  diagnostic  confidence in
differentiating  between normal and diseased lymph nodes.  COMBIDEX  received an
approvable letter from the FDA, subject to certain conditions, in June of 2000.

Lymph nodes are frequently  the site for  metastases of many different  types of
cancer,  including breast cancer and prostate cancer.  Computed  tomography (CT)
and MRI are  the  methods  currently  used  for  imaging  lymph  nodes.  Current
guidelines for imaging lymph nodes are that nodes greater than 10 mm in size are
usually  deemed  cancerous  while  nodes  less than 10 mm in size are  generally
presumed  normal.  Without  the  use of an  imaging  agent,  CT and  MRI  cannot
distinguish  between  lymph nodes that are enlarged due to the  infiltration  of
cancerous  cells as opposed to  inflammation  nor can these  methods  accurately
detect disease in nodes that are not enlarged.

ABOUT ADVANCED MAGNETICS
Advanced  Magnetics,  Inc.  is  a  developer  of  superparamagnetic  iron  oxide
nanoparticles  used  in  pharmaceutical  products.  As a  leader  in its  field,
Advanced Magnetics is dedicated to the development and  commercialization of its
proprietary  nanoparticle  technology for use in  therapeutic  iron compounds to
treat  anemia,  as well as  novel  imaging  agents  to aid in the  diagnosis  of
cardiovascular   disease  and  cancer.   For  more  information  about  Advanced
Magnetics, please visit the company's website at www.advancedmagnetics.com,  the
content of which is not part of this press release.

ABOUT CYTOGEN CORPORATION
Founded in 1980,  Cytogen  Corporation  of  Princeton,  NJ is a  product-driven,
oncology-focused  biopharmaceutical  company that develops and  commercializes a
balanced  portfolio of oncology products that address the unmet medical needs of
patients and their physicians. Cytogen's marketed products include QUADRAMET(TM)
(samarium Sm-153 lexidronam  injection) and PROSTASCINT(R)  (capromab pendetide)
kit for the  preparation  of Indium  In-111  capromab  pendetide  in the  United
States.  Cytogen has exclusive  United States  marketing  rights to  COMBIDEX(R)
(ferumoxtran-10),  an investigational molecular imaging agent consisting of iron
oxide  nanoparticles  for use in conjunction with magnetic  resonance imaging to
aid in the differentiation of cancerous from non-cancerous lymph nodes, which is




under  review  by the  U.S.  Food  and  Drug  Administration.  Cytogen  is  also
developing therapeutics targeting  prostate-specific  membrane antigen (PSMA), a
protein  highly  expressed  on the  surface  of  prostate  cancer  cells and the
neovasculature of solid tumors.  Full prescribing  information for the Company's
products is available at www.cytogen.com or by calling 1-800-833-3533.  For more
information, please visit the Company's website at www.cytogen.com, which is not
part of this press release.

For Advanced Magnetics:
THIS  DOCUMENT  CONTAINS  FORWARD-LOOKING  STATEMENTS  WITHIN THE MEANING OF THE
PRIVATE  SECURITIES  LITIGATION REFORM ACT OF 1995 AND FEDERAL  SECURITIES LAWS.
ANY STATEMENTS  CONTAINED IN THIS PRESS RELEASE THAT DO NOT DESCRIBE  HISTORICAL
FACTS ARE  FORWARD-LOOKING  STATEMENTS THAT INVOLVE RISKS AND UNCERTAINTIES THAT
COULD CAUSE ACTUAL  RESULTS TO DIFFER  MATERIALLY  FROM THOSE  DISCUSSED IN SUCH
FORWARD-LOOKING  STATEMENTS. SUCH RISKS AND UNCERTAINTIES INCLUDE THE FOLLOWING:
(1) THE  POSSIBILITY  THAT EVEN THOUGH THE RESPONSE  WAS DEEMED  COMPLETE BY THE
FDA,  THE FDA  COULD  RESPOND  TO  THIS  SUBMISSION  BY  ISSUING  AN  ADDITIONAL
APPROVABLE LETTER WITH ADDITIONAL CONDITIONS FOR APPROVAL OR THE FDA COULD ISSUE
A NOT APPROVABLE  LETTER; (2) THE ABILITY TO RESOLVE FINAL LABELING FOR COMBIDEX
WITH THE FDA; (3) THE  POSSIBILITY  THAT EVEN THOUGH THE FDA HAS ASSIGNED A USER
FEE  GOAL  DATE OF  MARCH  30,  2005,  THE FDA  MAY  NOT ACT BY SUCH  DATE;  (4)
UNCERTAINTIES   REGARDING  MARKET  ACCEPTANCE  OF  COMBIDEX;  (5)  UNCERTAINTIES
RELATING TO THIRD-PARTY  REIMBURSEMENTS;  (6) UNCERTAINTIES RELATING TO ADVANCED
MAGNETICS' ABILITY TO CONTINUE TO OPERATE AT COMMERCIAL SCALE IN COMPLIANCE WITH
FDA   REGULATIONS  AND  OTHER   APPLICABLE   MANUFACTURING   REQUIREMENTS;   (7)
UNCERTAINTIES  RELATING  TO  PATENTS  AND  PROPRIETARY  RIGHTS  AND OTHER  RISKS
IDENTIFIED IN ADVANCED  MAGNETICS,  INC.'S  SECURITIES  AND EXCHANGE  COMMISSION
FILINGS.  ADVANCED MAGNETICS CAUTIONS READERS NOT TO PLACE UNDUE RELIANCE ON ANY
FORWARD-LOOKING  STATEMENTS  WHICH  SPEAK  ONLY AS OF THE DATE  THEY  ARE  MADE.
ADVANCED  MAGNETICS  DISCLAIMS ANY  OBLIGATION TO PUBLICLY  UPDATE OR REVISE ANY
SUCH STATEMENTS TO REFLECT ANY CHANGE IN  EXPECTATIONS OR IN EVENTS,  CONDITIONS
OR  CIRCUMSTANCES  ON WHICH ANY SUCH STATEMENTS MAY BE BASED, OR THAT MAY AFFECT
THE  LIKELIHOOD  THAT  ACTUAL  RESULTS  WILL  DIFFER FROM THOSE SET FORTH IN THE
FORWARD-LOOKING STATEMENTS.

For Cytogen:
THIS PRESS RELEASE  CONTAINS  CERTAIN  "FORWARD-LOOKING"  STATEMENTS  WITHIN THE
MEANING OF THE PRIVATE SECURITIES  LITIGATION REFORM ACT OF 1995 AND SECTION 21E
OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.  ALL STATEMENTS,  OTHER THAN
STATEMENTS OF  HISTORICAL  FACTS,  INCLUDED IN THIS PRESS RELEASE  REGARDING OUR
STRATEGY,  FUTURE OPERATIONS,  FINANCIAL  POSITION,  FUTURE REVENUES,  PROJECTED
COSTS,  PROSPECTS,  PLANS  AND  OBJECTIVES  OF  MANAGEMENT  ARE  FORWARD-LOOKING
STATEMENTS.  SUCH  FORWARD-LOOKING  STATEMENTS  INVOLVE  A NUMBER  OF RISKS  AND
UNCERTAINTIES  AND INVESTORS ARE CAUTIONED NOT TO PUT ANY UNDUE  RELIANCE ON ANY
FORWARD-LOOKING  STATEMENT.  THERE ARE A NUMBER OF IMPORTANT  FACTORS THAT COULD
CAUSE  CYTOGEN'S  RESULTS  TO DIFFER  MATERIALLY  FROM THOSE  INDICATED  BY SUCH
FORWARD-LOOKING  STATEMENTS.  IN PARTICULAR,  CYTOGEN'S BUSINESS IS SUBJECT TO A
NUMBER OF SIGNIFICANT RISKS, WHICH INCLUDE,  BUT ARE NOT LIMITED TO: THE RISK OF
OBTAINING  THE  NECESSARY  REGULATORY  APPROVALS;  THE RISK OF WHETHER  PRODUCTS
RESULT  FROM  DEVELOPMENT  ACTIVITIES;  THE  RISK OF  SHIFTS  IN THE  REGULATORY
ENVIRONMENT  AFFECTING  SALES OF CYTOGEN'S  PRODUCTS SUCH AS  THIRD-PARTY  PAYOR
REIMBURSEMENT  ISSUES;  THE RISK  ASSOCIATED  WITH  CYTOGEN'S  DEPENDENCE ON ITS
PARTNERS FOR DEVELOPMENT OF CERTAIN PROJECTS, AS WELL AS OTHER FACTORS EXPRESSED
FROM TIME TO TIME IN CYTOGEN'S PERIODIC FILINGS WITH THE SECURITIES AND EXCHANGE
COMMISSION  (THE  "SEC").  AS A RESULT,  THIS  PRESS  RELEASE  SHOULD BE READ IN
CONJUNCTION WITH CYTOGEN'S  PERIODIC  FILINGS WITH THE SEC. THE  FORWARD-LOOKING
STATEMENTS  CONTAINED HEREIN ARE MADE ONLY AS OF THE DATE OF THIS PRESS RELEASE,
AND CYTOGEN  UNDERTAKES NO OBLIGATION  TO PUBLICLY  UPDATE SUCH  FORWARD-LOOKING
STATEMENTS TO REFLECT SUBSEQUENT EVENTS OR CIRCUMSTANCES.

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