National Institutes of Health Chief Bernadine Healy's "blueribbon" review panel on the gp160 AIDS vaccine votedunanimously on Monday to recommend multiproduct trialsrather than a trial exclusively devoted to MicroGeneSys Inc.'sgp160 AIDS vaccine.

Healy had assembled the panel following Congress'unprecedented vote providing the Army with $20 million for atrial of MicroGeneSys' vaccine. The panel will makerecommendations to Congress about how any trials should beconducted.

There is considerable feeling that some good will come ofCongress' so-called end run around peer review. "This stupidamendment has done more than anyone ever thought a stupidamendment would do to make us focus on vaccine strategy,"FDA Chief David A. Kessler told BioWorld.

When the panel first met on Nov. 5, there was already a strongconsensus that any trial should include more than one product.

The panel wrestled with the conflict of having what membersagreed would be insufficient data to proceed with a Phase IIItrial under normal circumstances on the one hand and theurgency to act in the face of a mortal epidemic on the other --as well as the desire not to lose out on $20 million.

Since it would not take too long to obtain data on clinical endpoints, panel members debated basing trials on surrogatemarkers. There was no evidence from any of 24 Phase I andPhase II trials that existing vaccines reduce viral burden,although vaccines have shown immunogenicity. In light of this,virologist Dani Bolognesi of Duke University insisted that for aPhase III trial to be valuable, there must be a hypothesis ofmechanism as to how such a vaccine might fight the infection.

Robert Redfield of the Department of Retroviral Research atWalter Reed Army Institute of Research, described "verypreliminary" data from two patients suggesting that the gp160vaccine might be disabling some virus particles withoutclearing them by causing mutations in the transcriptionalregion. But sufficient data to support this hypothesis won't beavailable for about a year, Redfield said.

At the end of the day, the two leading criteria for trials were"reducing viral burden and reconstituting the immune systemso you can tolerate viral load so you can fight off infections,"Healy said.

Healy suggested that trials should not be wedded to anyparticular company or product, but should be free to includeany promising products that appear.

In general, panel members expressed strong interest in backingthe trials with careful scientific measurements that wouldprovide useful data even if the trials were a clinical flop, andthere was talk of "substudies of substudies."

This, of course, raised questions about cost in National CancerInstitute Director Sam Broder's mind. Panel member MarkHarrington of the Treatment Action Group of New Yorksuggested a partnership with industry. And Marty Rose ofGenentech Inc. and a representative of Biocine Co., a jointventure between Chiron Corp. and Ciba-Geigy, said theircompanies would be willing to make the vaccine available freeof charge.

In return, the Biocine representative said, industry should playa role in setting up the trials.

-- David C. Holzman Special to BioWorld

(c) 1997 American Health Consultants. All rights reserved.