By Frances Bishopp

Joining an elite group of biotech companies with three or more products on the market, Cytogen Corp. has received FDA clearance to market Quadramet for the treatment of severe pain associated with cancers that have spread to the bone.

Quadramet (Samarium Sm 153 Lexidronam Injection) is a radiopharmaceutical drug (stable complex of radioactive samarium and a tetraphosphonate chelator EDTMP) that targets the bone and concentrates in areas that have been invaded with tumor. Quadramet emits both a beta particle (therapeutic component) and a gamma photon (imaging element) and has a physical half-life of 46.3 hours.

Cytogen, of Princeton, N.J., has licensed the exclusive rights to manufacture and market Quadramet for oncology applications in the U.S. to Dupont Merk Pharmaceutical Co., of Wilmington, Del., while retaining the right to co-promote the product. Quadramet will be marketed by the Radiopharmaceuticals Division of The Dupont Merk Pharmaceutical Co., of North Billerica, Mass., under the DuPont Pharma name.

In October 1996, Cytogen obtained FDA approval to market its diagnostic prostate cancer imaging agent, ProstaScint, and launched it in February 1997. Cytogen's first commercial product, OncoScint CR/OV, is a monoclonal antibody-based imaging agent for the detection of colorectal and ovarian cancers. It was approved by the FDA and marketed in 1992.

Quadramet is indicated for the relief of pain in patients with confirmed osteoblastic metastatic bone lesions that enhance on radionuclide bone scan. Osteoblastic (bone forming) lesions are most commonly associated with advanced prostate, breast and lung cancer. Approximately 400,000 patients will develop bone metastases this year in the U.S. and more than 75 percent of these patients will experience severe, chronic bone pain.

Jean Slayback, with corporate communications at Cytogen, said Quadramet is in clinical trials for several other indications: therapy for bone metastases (Phase II) and pain relief for refractory rheumatoid arthritis (Phase 1).

Quadramet is a bone pain therapy agent which, once injected into a patient, targets the sites of new bone formation, thereby concentrating in the areas that have been invaded with metastatic tumor. Quadramet, which goes to the source of cancer bone pain and irradiates the osteoblastic tumor sites, may be administered on an outpatient basis.

Patients who respond to Quadramet might begin to notice the onset of pain relief one week after injection. Patients who experience reduction in pain may be encouraged to decrease their use of opioid analgesics.

Any Quadramet not taken up by the bone is excreted from the body within six hours. This minimizes radiation exposure to normal bone marrow, which limits the myelosuppressive effects of Quadramet. The myelosuppressive effect is temporary and typically recovers to pretreatment levels within eight weeks.

Andrea Scibelli, public affairs manager for Dupont Merk Radiopharmaceuticals, said the company hopes to have the product available by mid-May. It will be sold throughout the U.S. through traditional outlets, radiopharmacies specifically.

"Quadramet is our first therapeutic product," Scibelli said, "and the second oncology product we have launched this year." The first product was Verluma, a diagnostic developed with NeoRx Corp., of Seattle. Other products owned and developed by Dupont Merk are Cardiolite for heart imaging and Neurolite for brain imaging.

"There has been a compassionate use program going on since the conclusion of the clinical trials," Scibelli said, "for those patients who were experiencing pain and wanted to continue to receive Quadramet therapy."

As of Dec. 31, 1996, Cytogen had approximately $35 million in cash. Cytogen's stock (NASDAQ:CYTO) closed Monday at $5.812, up $0.562. *