Trimeris Inc. reported positive 24-week results Thursday from its second pivotal Phase III trial of fusion inhibitor T-20 to treat HIV, which will pave the way for an application with the FDA to market the drug.

Durham, N.C.-based Trimeris about a month ago reported positive results from the first Phase III study of T-20, called TORO 1. Trimeris, along with partner Hoffmann-La Roche Inc., of Nutley, N.J., said the two studies would serve as the basis for a new drug application for T-20, which has fast-track designation, in both the U.S. and Europe in the early second half of the year. (See BioWorld Today, April 19, 2002.)

"We're very excited - not only the people at Trimeris but also the people at Roche," said Nick Ellis, Trimeris' executive vice president and chief business officer. "These are the first Phase III studies to establish the increased antiviral potency of an antiretroviral on back of a state-of-the-art background regimen."

T-20 is the most advanced in the investigational class of antiretrovirals called fusion inhibitors, which work to block a virus before it enters and takes over a host cell. Fusion inhibitors are one of three types of entry inhibitors. The two others are attachment inhibitors and co-receptor inhibitors.

Trimeris plans to apply for conditional approval from the FDA with the 24-week data, given its fast-track designation, but would continue with TORO 2, the second pivotal Phase III study, Ellis said. It would then report 48-week results, and if they continue to be positive, the company would file for full approval with the FDA, he said.

"This certainly gives patients who are running out of options an option they didn't have," Ellis said. "It gives them some coverage for virus that has become resistant to the other classes of drugs.

"We believe it's going to become the foundation of treatment in treatment-experienced patients and be the bridge to get them to the next generation of medications," he said.

The TORO 2 study included 504 HIV-infected patients in Europe and Australia who were treatment-experienced and had developed resistance to each of the three classes of anti-HIV drugs. The primary endpoint was the difference in the magnitude of decrease in HIV between the arm receiving T-20 as part of a combination therapy and the control arm.

Patients started the trial with a median HIV RNA level of over 5 log10 copies/mL and had considerable experience with multiple anti-HIV drugs. After 24 weeks, patients receiving T-20 as part of a combination regimen achieved a statistically significant mean reduction in HIV levels of 1.43 log10 copies/mL compared to a mean of 0.65 log10 copies/mL for those who were in the control arm (p<0.0001).

Patients treated with T-20 received it as one 90-mg self-injection twice daily. Three percent of the T-20 patients discontinued the study as a result of injection-site reactions. Of those receiving T-20, 17 percent discontinued the study at 24 weeks due to virological failure.

"These are very sick patients and for many to fail virologically and drop out is not abnormal," Ellis said, explaining that the company had designed the trial anticipating 20 percent discontinuation.

Ellis said Trimeris will close the database in early June and probably present a full report at TORO 2 at the International Conference on Antimicrobial Agents and Chemotherapy in the fall.

Roche and Trimeris entered the collaboration in 1999, which was Trimeris' first corporate deal. At the time, it was projected to mean as much as $88 million to Trimeris. They extended the alliance in 2001. (See BioWorld Today, June 20, 2001, and July 13, 1999.)

The alliance also includes the development of another anti-HIV fusion inhibitor, T-1249, which is in Phase I/II studies. It is slated to begin Phase II studies late in the second half of this year, Ellis said, making it two and a half to three years behind T-20.

Earlier this month, Trimeris entered a collaboration with Neokimia Inc., of Sherbrooke, Quebec, to discover and develop small-molecule anti-HIV fusion inhibitors. (See BioWorld Today, May 6, 2002.)

Trimeris' stock (NASDAQ:TRMS) fell $2.56 Thursday to close at $49.42. n