WASHINGTON – Stock values plummeted for the companies behind the molecular imaging agent Combidex (ferumoxtran-10), following a negative FDA panel vote. That recent thumbs-down damaged shares of Advanced Magnetics (Cambridge), developer of the product, by two-thirds and halved the stock of Cytogen (Princeton, New Jersey).

Officials from Cytogen declined to speak to Medical Device Daily's sister publication BioWorld Today, though Advanced Magnetics' Chairman, President and CEO Jerome Goldstein said that the companies "look forward to meeting with the FDA to determine appropriate next steps."

Advanced Magnetics' stock on the AMEX plunged $12.34 last Thursday, or 66%, to $6.71, while shares in Cytogen on the Nasdaq dropped $6.69 to close at $6.32.

Citing insufficient clinical data, the agency's Oncologic Drugs Advisory Committee voted 15-4 against supporting a broad indication for Combidex. Panel members declined a broad indication for the product's use to differentiate metastatic from non-metastatic lymph nodes across all cancer types.

The application is seeking approval for the product's intravenous administration and use as an MRI contrast agent to assist in the differentiation of lymph nodes in patients with confirmed primary cancer who are at risk for lymph node metastases.

Cytogen had been drawing up plans to market the diagnostic product according to terms of a commercialization agreement with Advanced Magnetics.

Data underlying the apoplication included findings published in the New England Journal of Medicine showing that Combidex assisted in detecting lymph-node metastases as small as 2 mm in prostate cancer patients. Other data, reported in Radiology, demonstrated the imaging agent's sensitivity for detecting the spread of cancer to lymph nodes in patients with urinary bladder cancer. Newer findings published in the Public Library of Science showed the feasibility of semi-automated analysis of Combidex-enhanced MRI in nodal staging.

Several panel members expressed enthusiasm for the product's potential compared to current lymph node imaging techniques, which include computed tomography and MRI without contrast. Nevertheless, the broad indication sought in the NDA proved to be the major stumbling block.

Safety issues were not of paramount concern to the committee, although in FDA briefing documents released just before the panel meeting, the agency raised a question about a single study-related incident in which a patient died after bolus administration of Combidex, which is made of iron oxide nanoparticles. Two other patients experienced serious but non-fatal reactions following bolus dosing, but the companies applied for administration via a 30-minute intravenous infusion.

A final FDA decision is expected by March 30, and the agency typically follows its panels' recommendations.