Phase III clinical studies fully recruited on schedule

Basel, Switzerland and Durham, N.C. August 9, 2001 - Roche and Trimeris, Inc. (NASDAQ:TRMS) today announced that both adult pivotal Phase III clinical studies for the novel drug T-20 are fully recruited on schedule. Approximately 1000 people living with HIV across Europe, Australia, North America and Brazil are currently participating in studies to evaluate the first in a new class of investigational drugs, fusion inhibitors. Roche and Trimeris aim to submit T-20 for European and US Regulatory approval during 2002.

�Both Roche and Trimeris are acutely aware that there are many people living with HIV who are in desperate need of new treatment options right now,� said Miklos Salgo, T-20 Clinical Science Leader, Roche. �The completion of patient recruitment for the phase III programme is a major achievement for everyone involved. These pivotal studies are intended to contribute insight into the development of a vital new class of HIV drugs which offers hope to patients who have developed resistance to their current combination therapy regimens and need new options.�

Multi-drug resistance to currently approved anti-HIV drugs is a significant issue in the clinical management of HIV today. T-20, because of its novel mechanism of action, is being evaluated as a treatment for patients who are heavily pre-treated with currently approved antiretroviral medications and have developed resistance to one or more of these agents over time.

The two adult T-20 pivotal phase III studies are T20-301 and T20-302. T20-301 is being conducted in North America and Brazil and completed enrollment in June 2001. T20-302 is being conducted in Australia, Belgium, France, Germany, Italy, Netherlands, Spain, Sweden, Switzerland, and the UK and completed enrollment on August 8 2001. The two randomized, open-label trials will assess over 1000 patients at 58 centers. Patients recruited into the trials, among other entry criteria, have prior experience and/or documented resistance to each of the three classes of approved antiretrovirals.

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Notes to editors:

One of the biggest challenges facing those living with HIV is resistance to currently available therapies. Thirty to fifty percent of infected patients have a strain of the virus that has developed resistance to the various antiviral treatments and the combination options available to them are therefore reduced. Roche and Trimeris are committed to discovering and developing treatments for patients in need of new options.

Roche and Trimeris are working together to mobilize the considerable resources required to support the rapid development of T-20, the first member of a new class of investigational anti-HIV drugs known as Fusion Inhibitors. Unlike existing AIDS drugs that work inside the cell and target viral enzymes involved in the replication of the virus, T-20 inhibits fusion of HIV with host cells before the virus enters the cell and begins its replication process. A second-generation fusion inhibitor, T-1249 is currently being evaluated in Phase I/II clinical trials. In June 2001, Roche and Trimeris announced a joint research agreement to identify and develop additional HIV Fusion Inhibitor Peptides.

T-20 has received fast-track designation by the FDA in the US and is being considered for fast-track approval in Europe for the treatment of HIV-infected individuals. Fast-track is granted to expedite the development of products that may provide a significant improvement in the safety or effectiveness of the treatment for a serious or life-threatening disease.

Headquartered in Basel, Switzerland, Roche is one of the world�s leading research-oriented healthcare groups in the fields of pharmaceuticals, diagnostics and vitamins. Roche�s innovative products and services address needs for the prevention, diagnosis and treatment of disease, thus enhancing people�s well-being and quality of life.

About Trimeris Inc.

Trimeris is a development stage, biopharmaceutical company engaged in the discovery and development of novel therapeutic agents that block viral infection by inhibiting viral fusion with host cells.

Trimeris� lead product candidate,T-20, which is now being co-developed with Roche, is currently in Phase III clinical trials. Trimeris and Roche are also currently co-developing a second fusion inhibitor product candidate, T-1249, which also inhibits HIV fusion. T-1249, like T-20, has received fast-track designation from the FDA and is undergoing Phase I/II clinical testing. For more information on Trimeris, Inc., visit the company's web site at www.trimeris.com