Cytogen Reports Presentation of QUADRAMET(TM) Clinical Data at the Eleventh Annual Prostate Cancer Foundation Scientific Retreat.

Cytogen Corporation , a product-driven biopharmaceutical company, today announced the presentation of data from two prospective multi-center studies relating to its lead therapeutic product QUADRAMET(TM) (samarium Sm-153 lexidronam injection), a non-opioid alternative currently available for rapid and long- acting pain relief from metastatic bone disease associated with various cancers. Clinical data from the two studies were presented during the Eleventh Annual Prostate Cancer Foundation Scientific Retreat held October 21- 24, 2004 in Lake Tahoe, Nevada.

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"These data clearly indicate that multiple doses of QUADRAMET can be safely administered to patients with painful metastatic bone disease provided normal white blood cell and platelet counts are present at the time of dosing," said A. Oliver Sartor, M.D., lead author of the presentation and director of the Stanley S. Scott Cancer Center at LSU Medical School in New Orleans, Louisiana. "For fixed interval dosing, we conclude that up to twice the current recommended dose every sixteen weeks is readily feasible from a safety perspective and can be repeated up to three times in patients with D2 prostate cancer without prior chemotherapy. Growth factor support was not used in either setting and non-hematologic toxicity was absent in both settings."

In a Phase IV clinical study, patients with metastatic bone disease received multiple administrations of QUADRAMET based on a recurrence of painful symptoms. Overall 132 administrations of 1.0 mCi/kg (the FDA approved dose) were given to 54 patients (range 2-11 doses per patient). White blood cell (WBC) and platelet toxicities observed following multiple doses were not clinically significantly greater than those observed following the initial dose. No grade 4 platelet or WBC toxicities were observed.

In a separate Phase I clinical study, 18 hormone sensitive prostate cancer patients received both multiple and higher doses of QUADRAMET at fixed time intervals. When doses of 2.0-2.5 mCi/kg were given every 12 weeks for four planned cycles to 12 patients, some patients were unable to receive the fourth cycle due to delayed recovery of platelets. An additional group of 6 patients were enrolled to receive 3 doses of 2.0 mCi/kg at intervals of 16 weeks. The three planned doses were completed in 5 out of the 6 patients. Time to nadir was 5-6 weeks for both WBC and platelets. No grade 3 or 4 platelet toxicities were observed at this dose and schedule. No grade 4 WBC toxicity was noted and 5 out of the 6 patients had grade 3 WBC decreases.

"It is now appreciated that interactions between bone and cancer cells are at the crux of the cancer metastasis problem and this concept was a dominant theme at the Prostate Cancer Foundation Scientific Retreat, which reinforces our enthusiasm for QUADRAMET's current and future role in delivering targeted radioactivity to the sites of stromal-epithelial interactions that are critical to the progression of the metastatic cascade to bone in prostate, breast and many other cancers," commented William Goeckeler, Ph.D., Senior Vice President of Operations with Cytogen. "The QUADRAMET data presented at this major scientific forum are especially important since they relate to the safety of repeated doses, as many physicians have relegated the use of this class of product until very late in the course of disease due, in part, to concerns related to the safety of administering repeated doses."

QUADRAMET is a targeted oncology product consisting of a short half-life therapeutic radionuclide (Samarium-153) bound to a small-molecule, bone- seeking phosphonate (EDTMP) that selectively concentrates in osteoblastic sites (areas of new bone formation), thereby delivering radioactivity in areas that have been invaded by metastatic tumor. Osteoblastic bone lesions can be associated with advanced prostate, breast, multiple myeloma and other cancers that have metastasized to bone, which can cause pain that may be severe and difficult to treat. Though indicated for pain palliation, ongoing clinical studies are investigating whether QUADRAMET may have direct anticancer activity and may also enhance the cytotoxic activity of chemotherapeutics and other agents.

Background Information

Research indicates that many patients with advanced cancer develop metastatic bone disease, the spread of cancerous cells from the original tumor to bones. It is estimated that 350,000 people die with metastatic bone disease annually in the United States. Pain is one of the most common symptoms associated with metastatic bone disease. Studies have shown that many patients with cancer (especially older adults) do not receive adequate pain relief. Effective pain control can help patients stay involved not only in their cancer treatment but also in the activities of daily living.

QUADRAMET Indication Information

QUADRAMET is indicated for the relief of pain in patients with confirmed osteoblastic metastatic bone lesions that enhance on radionuclide bone scan. This press release describes clinical applications that differ from that reported in the QUADRAMET package insert. QUADRAMET should not be given concurrently with chemotherapy or external beam radiation therapy unless the benefit outweighs the risk. QUADRAMET should not be given after either of these treatments until there has been time for adequate marrow recovery.

A copy of the full prescribing information for QUADRAMET may be obtained in the United States from Cytogen Corporation by calling toll-free 800-833- 3533 or by visiting the web site at http://www.cytogen.com/, which is not part of this press release.

About Cytogen Corporation

Founded in 1980, Cytogen Corporation of Princeton, NJ is a product-driven biopharmaceutical company that develops and commercializes innovative molecules that can be used to build franchises across multiple markets. 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) for all indications. COMBIDEX, an investigational molecular imaging agent consisting of iron oxide nanoparticles, is currently being developed for use in conjunction with magnetic resonance imaging to aid in the differentiation of cancerous and non-cancerous lymph nodes, and 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 http://www.cytogen.com/ or by calling 1-800-833-3533. For more information, please visit the Company's website at http://www.cytogen.com/, which is not part of this press release.

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.

CONTACT: Stacy Shearer, Investor Relations, Cytogen Corporation, [phone], [e-mail]

Web site: http://www.cytogen.com/