Panel backs DDI despite uncertainties.

In an unusual move, an advisory panel to the Food and Drug Administration has recommended approving the AIDS drug didanosine even though clinical trials to establish the treatment's efficacy are still in progress. The panel, which made its recommendation two weeks ago, advised FDA to allow sales of didanosine - also called DDI for its chemical name, dideoxyinosine-for adults and children with AIDS who cannot tolerate zidovudine (AZT), the only other approved AIDS drug.

The panel based its decision primarily on data from "expanded access" trials of DDI, begun in 1989 (SN: 10/7/89, p. 231). Such trials allow researchers to collect some information on a drug's efficacy from seriously ill patients who receive the treatment outside statistically controlled trials. The advisory panel also considered data from two recent safety trials, one of which involved children (SN: 5/19/90, p.315; 1/26/91, p.55).

Unlike zidovudine, DDI does not cause anemia. However, it can cause pancreatitis, a potentially fatal swelling and inactivation of the pancreas. DDI's manufacturer, Bristol-Myers Squibb Co., reported last year that six of the roughly 9,000 patients participating in DDI clinical trials or expanded access programs had died of pancreatitis (SN: 3/17/90,p.165).

DDI's dangerous side effect, coupled with the paucity of efficacy data prompted concern among some members of the FDA advisory panel. Although University of Chicago statistician Paul Meier voted to recommend approval, he cautioned that the panel might be "ratcheting down" the usual standards for drug approval in order to speed a new AIDS treatment to market. One of the nine panelists voted against DDI approval.

Although FDA usually follows the recommendations of its advisory committees, the agency has not announced when it will make a final decision on DDI.