The FDA has notified Immunomedics Inc. that its colorectal cancerimaging agent, ImmuRAID-CEA, is not approvable at this time. Thedecision surprised some analysts, coming three years after the productlicensing application (PLA) was filed, and after consistently positivereports of clinical trial results.Immunomedics' stock dropped 36 percent ($2) Wednesday,(NASDAQ:IMMU) to close at $3.50.Immunomedics said it plans to meet promptly with the FDA to clarifythe questions and issues raised in the agency's notification letter. Thecompany declined to provide any details about the reasons given forthe FDA's denial.However, Amy Factor, Immunomedics' executive vice president, toldBioWorld: "The issues that were raised in the FDA's letter relatespecifically to the PLA and not to the overall technology."The company's refusal to divulge any details about the FDA's letterappeared to surprise many analysts. Jean Anne Mire, a biotech analystwith Kemper Securities Inc. in Houston, said her company has put ahold on Immunomedics' stock until analysts have more information.This was a downgrade from the company's previous rating of "long-term buy.""It's clearly an important product for Immunomedics, and it's their firstproduct," Mire said. "It's unclear what is still required by the FDA.We'll have to wait and see." Mire said the impact of the denial onImmunomedics would depend on the issues raised by the FDA. "If thequestions are technical or production-related, the outcome could bepositive. If they are related to clinical data, the outlook could beconsiderably more negative."Mire said she was surprised by the FDA's action. "I expected that anFDA advisory panel might be convened because there are not manymonoclonal antibody imaging agents out there. I was not expectingnon-approval," she said.Carol Werther, a biotech analyst with Cowen and Co. in Boston, saidImmunomedics' refusal to disclose the issues raised by the FDA mighthave contributed to the sharp decline in the price of the Morris Plains,N.J. company's stock _ especially given the poor performance ofother biotech stocks.Agent May Still Have A ChanceWerther said she thought ImmuRAID-CEA might still be approvablesince Cytogen's OncoScint CR/OV, which she described as a verysimilar product, has been approved. "But it seems to me it will not beapprovable this year, and that's a pretty strong negative for thecompany," she said.Werther noted that the effect of the non-approval on NeoRx, which isin a patent dispute with Immunomedics over its imaging technology,would depend on the reasons behind the FDA's decision.Without knowing these reasons, neither Mire nor Werther wouldpredict the effect of the FDA action on other Immunomedics products,including its infection-imaging agent, ImmuRAID-MN3, now ready fora PLA filing.Positive results of clinical trials with ImmuRAID-CEA, most recentlypublished in the March issue of the Journal of Clinical Oncology,reported that ImmuRAID-CEA accurately diagnosed the presence orabsence of colorectal tumors in 93 percent of cases in a 16-personstudy. In 81 percent of cases, ImmuRAID-CEA succeeded where CTscans or other diagnostics had failed.The only hint of potential problems came in May 1993, two years afterthe PLA was filed, when David Ortlieb, Immunomedics' president andCEO, said that the company had continued to conduct Phase III studieswith additional patients. Ortlieb said the data were being submitted tothe FDA. "We believe these additional data will support the broadclaims we are seeking concerning the product's safety, efficacy andutility, and eventually enable us to secure a broader label for its usage,"Ortlieb said.Factor said these additional trials were for the same protocols as theoriginal PLA, but in more patients, different settings, and with moresurgical data.ImmuRAID-CEA consists of an antibody fragment labeled with theradioisotope technetium-99m. It attaches to the tumor marker CEA(carcinoembryonic antigen) and allows for detection via a standardnuclear medicine camera.

-- Philippa Maister

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