Neoprobe Corp. (NYSE:NEOP) filed a formal response to a challenge to a pending FDA application for its flagship Lymphoseek compound, calling the citizen’s petition "inaccurate" and "misleading."

Last week, MSMB Capital Management submitted the petition asking the FDA to block Neoprobe’s application on the grounds that the drug’s pivotal trials suffered from vital mistakes. The allegations included charges that the trials are not adequately controlled and contain conflicts of interest that may have compromised their integrity.

Neoprobe was quick to issue a public response and filed its formal reply with the federal watchdog agency this week.

"Neoprobe’s management and board of directors take seriously any action aimed at harming our shareholders or delaying the availability to patients of a potentially helpful diagnostic agent," the company said in a press release. "We believe that we are appropriately addressing the current set of unwarranted or misleading statements and/ or filings made by parties whose motives and actions stand contrary to the interests of our shareholders and the patients and physicians we serve."

The formal response notes that MSMB Capital, a hedge fund, is a "short-seller who could potentially benefit financially from a decline in Neoprobe’s stock price."

"The Citizen Petition is baseless and replete with factual and regulatory misstatements, served under a cloak of legitimacy," the company wrote. "The petitioner selectively cites Neoprobe press releases, SEC filings and literature references, yet omits information from public filings, disclosures, and statements made by the company, as well as other relevant references from the literature, which are unfavorable to the petition. FDA regulations, however, require the disclosure of information, known to the petitioner, even if unfavorable to the petition."

Three allegations form the crux of the petition’s "factual inaccuracies, mis-characterizations, and misstatements," according to Neoprobe:

1. MSMB Capital mis-characterizes what Lymphoseek is designed to do, erroneously calling it "sentinel lymph node mapping," according to Neoprobe. "Indeed, as Neoprobe has repeatedly noted in SEC filings and other public disclosures, Neoprobe’s regulatory-appropriate clinical trials were designed to achieve an indication for ‘anatomical delineation of lymphatic tissue,’ not ‘sentinel lymph node mapping,’" the company wrote. "The distinction is critical to understanding the study design, and exemplifies the types of flaws evident throughout the petition."
2. The petition also questions the use of vital blue dye as the control compound for the study, rather than vital blue dye plus sulfur colloid. Neoprobe said the assertion "reveals the petitioner’s fundamental mis-characterization of the facts, and the legal and regulatory framework for the design of studies required for drug approval" because the FDA has not approved sulphur colloid for anatomic delineation of lymphatic tissue. "Thus, the only appropriate comparator in the instant case is vital blue dye, which received FDA approval for the indication sought by Lymphoseek," the company wrote.
3. Lastly, MSMB cites an "out-dated" 1994 article to support the assertion that the "truth standard" for the FDA’s Lymphoseek review should be axillary nodal dissection. "Not surprisingly, however, the petitioner fails to cite any FDA regulations that support this conclusion," Neoprobe wrote. "Petitioner conveniently ignores the substantial scientific advancement during the past seventeen years, demonstrating that axillary nodal dissection in the instant case would, in fact, have subjected patients to numerous, unnecessary risks, representing safety and ethical considerations in the conduct of such a study."

The Neoprobe rebuttal concludes by asking the FDA to dismiss the MSMB petition out-of-hand.