The US FDA has cleared an Investigational New Drug (IND) application for CYT-500, the Cytogen Corporation's lead therapeutic candidate targeting prostate-specific membrane antigen (PSMA). Cytogen expects to begin the first US phase I clinical trial of CYT-500 in patients with hormone-refractory prostate cancer subject to Institutional Review Board (IRB) approval at the planned clinical site.

This novel product candidate is designed to enable targeted delivery of a cytotoxic agent to PSMA-expressing cells. Cytogen retains full and exclusive development rights to CYT-500.

"This regulatory clearance by the FDA is an important step in our efforts to develop CYT-500. In a very short period of time, we have produced clinical quality drug and have received regulatory clearance to proceed with clinical trials, which we expect to initiate soon after IRB approval," Michael D. Becker, president and CEO of Cytogen said adding, "As a pioneer in PSMA-related research and development, these are significant steps forward for Cytogen that expand our focus on developing and commercializing novel therapeutic oncology products."

PSMA is a protein abundantly expressed on the surface of prostate cancer cells, with an increased expression in high-grade cancers, metastatic disease and hormone-refractory prostate cancer. PSMA is also present at high levels on the newly formed blood vessels, or neovasculature, needed for the growth and survival of many solid tumors.

Cytogen's marketed products include Quadramet (samarium Sm-153 lexidronam injection), Prostascint (capromab pendetide) kit for the preparation of Indium In-111 capromab pendetide, and Soltamox (tamoxifen citrate) in the United States. Cytogen's development pipeline consists of CYT-500, a therapeutic radiolabeled antibody targeting prostate-specific membrane antigen (PSMA), a protein highly expressed on the surface of prostate cancer cells and the neovasculature of solid tumours.