NeoRx Corp. planned to announce today that the Food and DrugAdministration has completed its review of clinical data on thecompany's OncoTrac small cell lung cancer imaging agent.

The Seattle company (NASDAQ:NERX) filed a product licenseapplication for OncoTrac in December 1989. OncoTrac linkstechnetium-99m to a monoclonal antibody fragment.

FDA advisory panels recently recommended approval of twoother MAb imaging agents. Centocor Inc.'s Myoscint to detectmyocardial necrosis in acute ischemic heart disease received apanel recommendation in November, the first MAb-basedimaging agent to do so. Last Friday, a panel recommendedapproval of Cytogen Corp.'s OncoScint to detect tumors incertain ovarian and colorectal cancer patients.

"The FDA had for many years been uncertain as to how toevaluate these products," said Dr. Darrell Salk, vice president ofmedical and regulatory affairs at NeoRx. "By last summer, theyhad developed a consensus throughout the agency on clinicalend points. That seems to have released a logjam."

The ability to identify lesions in indications such as tumors,blood clots and areas of inflammation is a sufficient end pointto indicate usefulness, Salk said.

Clinical trials of OncoTrac both identified lesions and showedthat the agent could be used to show how far the disease hasspread in order to decide what treatment to use, said Salk.

NeoRx has completed similar Phase III trials of OncoTrac fornon-small cell lung cancer. The company hasn't yet filed formarketing approval. NeoRx filed for approval of anotherOncoTrac imaging product for metastatic melanoma in 1988.

NeoRx shares were down 44 cents on Tuesday at $5. -- KarenBernstein

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