Data presented at the I^st International AIDS Society (IAS) Conference on HIV Pathogenesis and Treatment

Buenos Aires, Argentina, 11 July, 2001 -A clinical study with the novel HIV drug, T-20, has shown a high degree of acceptance amongst HIV patients for long-term self-administration of the drug by subcutaneous injection.

T-20 is the first in a new class of HIV drugs called fusion inhibitors and it works by preventing the HIV virus from 'fusing' with the host cell and taking it over. T-20 cannot be taken orally as it would be destroyed by digestive enzymes in the gut. As such, the drug has to be self-administered by injection under the skin twice a day and it is essential that patients are able to adhere to the daily injection routine.

�I cannot overemphasise the importance of developing new antiretroviral agents such as T-20 for extending the duration of combination therapies,� said Dr Calvin Cohen, physician and Research Director of the Community Research Initiative, Brookline, Mass., USA. �The real test for this novel drug will be its acceptance by patients. The study has shown that 98% of the patients who completed one year of therapy said that they would choose to continue with this drug. In effect they are giving T-20 the green light for long-term use which is critical for adherence to the therapy.�

The data was presented today to scientific experts attending the I^st International AIDS Society (IAS) Conference on HIV Pathogenesis and Treatment. The study was conducted to assess whether subcutaneous administration of T-20 would influence the patient�s ability to conduct normal activities of daily living (ADL). Patients completed written surveys reporting on the impact of the drug delivery on their ability to perform ordinary ADLs prior to initiating therapy and at 48 weeks or their last visit if they left the study before 48 weeks.

Data from the study showed that:

• 85% of the patients rated the ease of injection as being �very easy�, �easy� or �not bad�
• Only 15% rated it as �somewhat difficult� with none rating it �very difficult�
• The majority agreed that relative to other HIV drugs, injection of T-20 did not limit aspects of daily living such as intimacy, family life, working, walking uphill, cooking and bathing
• The majority of patients also agreed that subcutaneous injections had not limited ADL during the one-year trial

T-20 is being developed by the Swiss pharmaceutical company Roche and the US biopharmaceutical company Trimeris.

- ENDS -

More About T-20 and Fusion Inhibitors

T-20 is the first of a new class of investigational anti-HIV drugs known as fusion inhibitors. Fusion inhibitors belong to a broader category of investigational drugs known as �entry inhibitors,� all of which work in various ways to block the HIV virus before it takes over a host cell. Led by T-20, the fusion inhibitors are the furthest along in development in the entry inhibitor category. Fusion inhibition takes place after HIV attaches to a host cell to prevent the virus from fusing with the cell and taking it over.

T-20 cannot be taken orally because enzymes in the gut will break it down. Injecting T-20 under the skin bypasses the digestive enzymes of the gut and puts the intact molecule directly into the body.

Both T-20 and another developmental fusion inhibitor, T-1249, have received fast-track designation by the U.S. Food and Drug Administration (FDA) 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.

About Roche

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 inhibits fusion of the human immunodeficiency virus (HIV) with host cells, is currently in Phase III clinical trials and has received fast-track designation from the FDA. Trimeris' second fusion inhibitor product candidate, T-1249, has also received fast-track designation from the FDA and is in Phase I/II clinical testing

Trimeris Safe Harbor Statement

Note: Except for any historical information presented herein, matters resented in this release are forward-looking statements that involve risks and uncertainties. The results of Trimeris' previous clinical trials are not necessarily indicative of future clinical trials, and future results could differ materially from the results presented.

herein. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the �Risk Factors� section included in Trimeris' Form 10-K for the year ended December 31, 2000, filed with the Securities and Exchange Commission on April 2, 2001.