By Randall Osborne

The first antisense drug to reach Phase III trials, fomivirsen for cytomegalovirus (CMV) retinitis in AIDS patients, came through with additional positive results as reported by Isis Pharmaceuticals Inc.

Isis, of Carlsbad, Calif., said the data from the fomivirsen trial, known as the CS9 study, compare favorably with an earlier trial, known as CS2, in newly diagnosed patients. (See BioWorld Today, Feb. 6, 1998, p. 1.)

The goal of the 54-patient CS9 trial was to determine the best 330-microgram dosing regimen for those with an advanced form of the infection, which is a late-stage, debilitating complication of AIDS.

"What we have now is experience showing rapid and prolonged disease control in early-stage disease and more advanced disease," said Jane Green, senior director of investor relations for Isis.

In one CS9 regimen, 34 patients were treated with one dose per week for three weeks to provide induction, followed by maintenance dosing every other week. In a second regimen, 20 were treated at day one and day 15, followed by monthly dosing.

Efficacy Similar In Both Groups

Well-tolerated with similar efficacy in both groups, fomivirsen showed a better safety profile in the less intensive regimen. In both, the median time to observed progression was 90 days, and the median time to disease response was similar: 7.8 days in the first regimen, 9.8 in the second.

Data from the CS9 trial, when combined with data from a similar European study known as CS12, show even longer median times to observed disease progression: 112 days for the first regimen, 177 days for the second, with a similar safety profile.

"The whole program has four studies in it," said Jane Green, senior director of investor relations for Isis. The fourth study, of fomivirsen with ganciclovir, one of the standard antivirals, was under enrolled.

"Trends were heading in the right direction, but that's going to be a supportive study," Green said. The CS12 trial and the ganciclovir study "round out the package we will be submitting [as part of a new drug application] to the FDA very, very shortly."

Last summer, Isis signed a $20 million marketing deal for formivirsen with Atlanta-based CIBA Vision Corp., a subsidiary of Novartis AG, of Basel, Switzerland. (See BioWorld Today, July 16, 1997, p. 1.)

Isis' stock (NASDAQ:ISIP) closed Monday at $15.437, down $0.25. *

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