European Association of Nuclear Medicine Journal Article Reports New Data Regarding Administration of QUADRAMET(R) with Chemotherapy in Hormone Refractory Prostate Cancer Patients.

QUADRAMET represents part of a multi-disciplinary medical approach enabling medical oncologists, radiation oncologists and nuclear medicine physicians to manage pain from metastatic bone disease

PRINCETON, N.J. -- Cytogen Corporation (NASDAQ: CYTO) today reported the publication of a study by independent investigators evaluating the safety and efficacy of QUADRAMET([R]) (samarium Sm-153 lexidronam injection) in combination with chemotherapy for the treatment of patients with hormone-refractory prostate cancer (HRPC). The publication, "Clinical benefit of bone-targeted radiometabolic therapy with 153Sm-EDTMP combined with chemotherapy in patients with metastatic hormone-refractory prostate cancer" by Ricci, S. et al., appeared in the online issue of the European Journal of Nuclear Medicine and Molecular Imaging (Eur J Nucl Med Mol Imaging. 2007 Jan 23), the official journal of the European Association of Nuclear Medicine (EANM).

In the study, 45 patients were followed after treatment with QUADRAMET to evaluate the possible synergistic effect with chemotherapy. Assessments of clinical benefit included a comparison of palliative response, biochemical response and overall survival in the combination groups versus the non-combination group.

Outcomes were analyzed from three different groups. Fifteen of the 45 patients received QUADRAMET without any subsequent chemotherapy (Group A), 14 patients initiated chemotherapy three to five months after receiving QUADRAMET (Group B), and 16 patients initiated chemotherapy within one month after receiving QUADRAMET (Group C).

Patient demographics and baseline characteristics (histologic grade of the primary cancer, number of bone metastases, bone pain severity, and serum PSA levels) were well matched across treatment groups. Baseline hematologic parameters (hemoglobin levels, leukocyte/neutrophil counts, platelet counts) among the cohorts were also similar. The chemotherapies administered to patients in Groups B and C were very similar and consisted of mitoxantrone plus prednisone or estramustine phosphate.

Key findings of the study are summarized as follows:

* Hematologic toxicity. No severe toxicities were observed and QUADRAMET had no additive effects on chemotherapy-related myelotoxicity.

* Palliative response. Overall, some degree of pain relief was observed in over 70% of the patients, with an almost 30% rate of complete response. The proportion of patients exhibiting a positive palliative response increased from 53.3% in Group A to 71.4% in Group B and 87.5% in Group C. The difference in the proportion of favorable palliative responders reached statistical significance for Group C versus Group A (p=0.0388). Average duration of bone pain palliation in patients of Group A was three to four months, while it was nine to 10 months in patients of Group C.

* Biochemical response. Patterns of biochemical response (change in serum PSA levels) were similar to those observed for palliative responses with the proportion of patients responding increasing from Group A to Group B and highest overall in Group C with the difference between Groups A and C reaching statistical significance (p=0.0235).

* Overall survival. Group C had a median survival of 30 months versus 11 months for Group B and 10 months for Group A. The increase for Group C was statistically significant over both Group A (p=0.008) and Group B (p=0.023).

About Bone Metastases

Each year, more than 100,000 patients in the U.S. develop bone metastases from spread of their primary cancer. Bone is the third most common site of metastatic disease after liver and lung, and spread to bone is associated with considerable morbidity. This includes bone pain and fracture, spinal cord compression, and hypercalcemia. The incidence of bone metastasis is expected to increase over the next decade as patient survival improves due to advances in anticancer therapy. This will make the treatment of this problem more important in the overall management of the surviving cancer patient. The majority of skeletal metastases arise from primary tumors of the thyroid, kidney, lung, prostate, and breast, with the latter two accounting for about 80% of metastatic bone disease. While all bones can be affected, the most common site of disease spread is the spine with the subsequent development of spinal cord compression. In advanced breast cancer, a majority of skeletal events will occur every three to four months resulting in significant morbidity and impaired quality of life.

About QUADRAMET

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 is an oncology product indicated for pain relief that pairs the targeting ability of a small molecule, bone-seeking phosphonate (EDTMP) with the therapeutic potential of radiation (samarium Sm-153). Skeletal invasion by prostate, breast, multiple myeloma, and other cancers often creates an imbalance between the normal process of bone destruction and formation. QUADRAMET selectively targets such sites of imbalance, thereby delivering radioactivity to areas of the skeleton that have been invaded by metastatic tumor.

QUADRAMET has demonstrated a range of characteristics that may be advantageous for the treatment of pain arising from metastatic bone disease, including early onset of pain relief (patients may experience pain relief within the first week with maximal relief generally occurring at three to four weeks after injection), length of pain relief, lasting a median of four months in responding patients, and predictable and reversible bone marrow toxicity or myelosuppression that tends to return to pretreatment levels after eight weeks. QUADRAMET is administered as a single intravenous injection, usually on an outpatient basis, and exhibits selective uptake in areas of bone formation with little or no detectable accumulation in soft tissue.

QUADRAMET Safety Profile

QUADRAMET causes bone marrow suppression. In clinical trials, white blood cell counts and platelet counts decreased to a nadir of approximately 40% to 50% of baseline in 123 (95%) of patients within 3 to 5 weeks after QUADRAMET, and tended to return to pretreatment levels by 8 weeks. Because of the unknown potential for additive effects on bone marrow, QUADRAMET should not be given concurrently with chemotherapy or external beam radiation therapy unless the clinical benefits outweigh the risks. Blood counts should be monitored weekly for at least 8 weeks, or until recovery of adequate bone marrow function. Non-hematologic adverse events that occurred in 5% or more of patients and greater than placebo were pain flare (7%), diarrhea (6%), infection (7%), spinal cord compression (6.5%), arrhythmias (5%), and hematuria (5%). Patients who receive QUADRAMET should be advised that for several hours following administration, radioactivity will be present in excreted urine. To help protect themselves and others in their environment, precautions need to be taken for 12 hours following administration.

A copy of the full prescribing information for QUADRAMET, including warnings, precautions, adverse events and other safety information, may be obtained in the U.S. 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

Founded in 1980, Cytogen is a biopharmaceutical company dedicated to advancing the care of cancer patients by building, developing, and commercializing a portfolio of specialty pharmaceutical products. The Company's specialized sales force currently markets QUADRAMET([R]), PROSTASCINT([R]), and SOLTAMOX([TM]) to the U.S. oncology market. QUADRAMET is approved for the treatment of pain in patients whose cancer has spread to the bone, PROSTASCINT is a PSMA-targeting monoclonal antibody-based agent to image the extent and spread of prostate cancer, and SOLTAMOX is the first liquid hormonal therapy approved in the U.S. for the treatment of breast cancer in adjuvant and metastatic settings. In the first half of 2007, Cytogen plans to introduce its fourth approved oncology product to the U.S. market, CAPHOSOL([R]), a prescription medical device for the treatment of oral mucositis and dry mouth. The Company is also developing CYT-500, a third-generation radiolabeled antibody to treat prostate cancer. Cytogen's product-focused strategy focuses on attaining sustainable growth through clinical, commercial, and strategic initiatives.

A copy of the full prescribing information for CAPHOSOL, QUADRAMET, PROSTASCINT, and SOLTAMOX, including box warnings, may be obtained in the U.S. from Cytogen Corporation by calling toll free 800-833-3533 or by visiting Cytogen's web site at www.cytogen.com. The Company's website 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 successfully marketing SOLTAMOX and CAPHOSOL; 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. All information in this press release, including 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 this information to reflect subsequent events or circumstances.