AMERSHAM CERETEC REVIEW: MEDICAL PORTION OF NDA

AMERSHAM CERETEC REVIEW: MEDICAL PORTION OF NDA for the functional brain imaging agent was completed by FDA within 180 days because of the firm's cooperative effort with FDA in designing a clinical trial program, FDA Radiopharmaceutical Division staffer Eric Jones, MD, told FDA's Radiopharmaceutical Drugs Advisory Committee at its Nov. 21 meeting. "The agency has been very pleased with the way this agent, Ceretec, has been investigated and submitted for our review," Jones reported. "Ceretec is an example of a cooperative regulatory action between a commercial sponsor and the agency. We had pre-IND meetings that allowed Amersham and our division to reach an agreement on a format to facilitate the sponsor's collection of data required for our review." As a result of the cooperative effort, Jones noted, the data "was reanalyzed and reviewed by [the division] within the required 180 days." Part of the investigation agreement for Cerectec (technetium Tc 99m HMPAO or exametazime) was that Amersham would select one "well-defined indication" for the agent and then supplement its submission with data for additional imaging claims. Although the advisory committee was not asked to advise the agency on the approvability of the agent, FDA's interest in expediting review of the product may make the drug a likely candidate for one of the agency's traditional late-December approvals. In support of the brain imaging indication, Amersham conducted a Phase II and Phase III study in stroke and TIA (transcient ischemic attack) patients. The Phase II study, with 104 patients, and Phase III study, with 103 patients, were analyzed separately to meet FDA's two-study requirement. Efficacy was evaluated by comparing the diagnoses from two blinded investigators, who looked only at Ceretec images, with a diagnosis from a third investigator looking at all available clinical data outside of Ceretec images. Amersham reported that the percentage of Ceretec reviewers making the same diagnosis as the third reviewer was 52% to 73% (the first and second reviewers) in the Phase II study and 71-76% in the Phase III study. The Arlington Heights, Illinois-based firm noted that there were no adverse reactions reported in the studies, and that only three adverse reactions have been reported from overseas marketing and clinical data on approximately 1,200 patients: urticaria, erythema and pain at the injection site. Amersham also highlighted the fact that Ceretec is the first technetium-based agent that can cross the blood brain barrier. The agent allows the imaging of functional aberrations that cannot be seen with anatomical imaging methods. Amersham licenses the rights to Ceretec from the University of Missouri, where the parent compound, PNAO, was developed. The agent, after being labeled with technetium, can be injected for up to 30 minutes after preparation. Amersham's most recent approval was for the radioactive diagnostic agent indium In-III oxyquinoline, approved in December 1985.