FDA moving ahead with TSE rule, despite 'theoretical' risk from blood, plasma products.

Despite noting there is just a "theoretical risk" from blood and plasma products, FDA can be expected within the year to issue proposed rules regarding minimizing the risk of new variant Creutzfeldt Jakov Disease (vCJD) and other transmissible spongiform encephalopathies (TSE), a Center for Biologics scientist told an April 4 ExpertBriefings.com audio-conference.

David Asher, M.D., of the Laboratory of Bacterial, Parasitic & Unconventional Agents, Division of Emerging and Transfusion-Transmitted Diseases, CBER's Office of Blood Research & Review, said the rulemaking was outlined in a news conference in January 2004 by then Dept. of Health and Human Services Secretary Tommy Thompson, which would have made FDA's handling of TSEs similar to that of the U.S. Department of Agriculture's, in terms of risk in foods--notably, bovine spongiform encephalopathy (BSE), commonly called "mad cow disease."

Asher said FDA would issue a proposed rule within the year, not an interim final rule, adding the agency is not looking for "zero tolerance" of TSEs. All therapeutic products will be covered--human, animal drugs, medical devices and, of course, biologics. However, he said an interim final regulation on TSEs may be issued "in response to emergency situations" involving CJD/TSE.

During his hour-long briefing, Asher provided evidence from recent scientific research showing the nature of vCJD in health care products. He said the "risk of vCJD transmission by plasma derivatives is theoretical. Even in the U.K., no case of vCJD has been recognized in a recipient of a plasma derivative." And, he noted, there were no plasma-product CJD cases even during the height of the BSE epidemic, which rocked Britain in the mid-to-late 1990s.

Asher said, however, it "is especially difficult to communicate highly uncertain theoretical risks" and said involvement of "patient groups is helpful."

He also said there are three candidate devices for clearing TSE agents under review, one already CE-marked in Europe.

Asher added that "plasma-derivative methods can remove some infectivity" during manufacturing. He said "there is reason to be hopeful of removal of infectivity from labile-blood products," meaning plasma red cells and platelets. Leuko-reduction devices--filters designed to reduce white cells from the blood--are being studied and hold promise, he said. He urged industry to examine the proceedings of an FDA conference held Oct. 31, in which several manufacturers, including Pall, presented data on these devices.

Asked about vaccines and the effect of new devices for eliminating infectivity, Asher said: "If these devices prove their promise and are effective in improving human plasma, we don't see why they can't be effective in treating other materials, at least bovine plasma. But this won't reduce the need for careful sourcing for BSE sources."

Asher added that there has yet to be a case of a human being getting TSEs from a vaccine.

Asked about whether FDA would want to require animal-free materials in biologicals, Asher said: "Although we encourage the development of products that don't have animal materials, we realize there are legacy products and I don't see replacing established products."

A CD recording of Dr. Asher's talk, including his slides, is available from ExpertBriefings.com for $225 plus shipping. Please call [phone], or visit us online at www.ExpertBriefings.com.