Shares in Advanced Magnetics Inc. and Cytogen Corp. received a boost on news that their partnered molecular imaging agent, Combidex, received an approvable letter from the FDA despite a negative committee vote earlier this month. But an outright approval is not imminent, as the agency communicated a need for more data.
"After the ODAC meeting, there were any number of possibilities," Jerome Goldstein, Advanced Magnetics' chairman, president and CEO, told BioWorld Today. "This was perhaps better than a lot of possible outcomes."
In the approvable letter, the FDA suggested that new data be limited to a well-defined population of specific cancer types to demonstrate the product's efficacy. Such a suggestion stems from issues raised by the agency's Onocologic Drugs Advisory Committee, which voted 15-4 against supporting a broad indication for Combidex (ferumoxtran-10). The dissenters questioned how the data submitted by the company could be generalized across all tumor types, therefore declining to endorse its use to differentiate metastatic from non-metastatic lymph nodes across all cancer types.
That decision dropped Cambridge, Mass.-based Advanced Magnetics' shares by two-thirds to $6.65, and cut Princeton, N.J.-based Cytogen's stock in half to $6.26. (See BioWorld Today, March 4, 2005.)
"Now that we have an approvable letter," Goldstein said, "we will try to resolve with the agency what needs to be done before approval."
He said it would be "speculation" to suggest that more studies might be necessary, or whether the company might be able to acquire more specific data from its existing set of findings. But Goldstein noted that the product has a large share of backers, including "a number of prominent doctors sitting on our side" during the ODAC meeting.
"With Combidex, you're more able to stage cancers that metastasize to lymph nodes," he said. "Then you have better therapy, and that leads to a better outcome. That's the expectation."
Goldstein added that related diagnostic techniques haven't changed in decades, and current methods such as computed tomography and MRI without contrast are unable to distinguish between metastasized and non-metastasized cancers. Combidex allows that differentiation, Goldstein said.
Its original new drug application sought approval for the product's intravenous administration and use as a magnetic resonance imaging contrast agent to assist in the differentiation of lymph nodes in patients with confirmed primary cancer who are at risk for lymph node metastases. Data underlying the NDA included findings showing that Combidex assisted in detecting lymph node metastases as small as 2 millimeters in prostate cancer patients, as well as other data demonstrating its sensitivity in detecting the spread of cancer to lymph nodes in patients with urinary bladder cancer. Other findings showed the feasibility of semi-automated analysis of Combidex-enhanced MRI in nodal staging.
"Is it perfect?" Goldstein asked rhetorically. "Of course not. Nothing is perfect. But it's much better than what's out there now."
Cytogen, on board as a marketing partner, also could be involved in the FDA dialogue process going forward. Goldstein declined to say when such talks would get under way, but said the outcome would be made public when a final direction is set.
On Thursday, both companies' shares gained about 8 percent. Advanced Magnetics' stock (AMEX:AVM) gained 68 cents, or 7.8 percent, to close at $9.45, while shares in Cytogen (NASDAQ:CYTO) gained 46 cents, or 8.1 percent, to close at $6.16.