BUENOS AIRES (July 11, 2001) - Data evaluating patient acceptance of the subcutaneous administration of T-20, an investigational HIV fusion inhibitor being developed jointly by Roche and Trimeris (Nasdaq: TRMS), are being presented today at the First International AIDS Society (IAS) Conference on HIV Pathogenesis and Treatment in Buenos Aires, Argentina. These data, collected in a substudy of the T20-205 Phase II clinical trial, suggest that subcutaneous delivery of T-20 was well-accepted by patients over the 48 week observation period. Additional data from a different Phase II study, T20-208, presented in a late breaker poster session, indicate that T-20 can be administered via subcutaneous injections delivered as one 90 mg dose twice daily, rather than by two twice-daily injections, which were used in earlier clinical studies.

"Two of the biggest challenges facing patients with HIV are adherence to therapy and resistance. It is critically important to develop new antiretroviral agents that have the potential to treat patients with extensive resistance, and identify medications that will be tolerated over the long term," said Cal Cohen, M.D., research director, Community Research Initiative in Brookline, Massachusetts. "We are very pleased to report that the patients in this year-long trial, on average, did not view subcutaneous delivery of T-20 as interfering with daily life."

This substudy was conducted to assess whether subcutaneous administration of T-20 would influence a patient's ability to conduct normal activities of daily living (ADL). A total of 55 patients completed written surveys evaluating the impact of drug delivery on their ability to perform ordinary ADL prior to initiating therapy and at 48 weeks or at their last study visit. Assessment of ADL was based on established survey instruments with questions added to assess HIV-specific issues, including privacy and sexuality. Patients also rated issues such as ease of injection, medication storage and reconstitution, as well as disposal of needles.

Eighty-five percent of patients rated the procedure of injection as "very easy/easy" or "not bad." Sixty two percent of patients "somewhat agreed" or "strongly agreed" with the statement that "relative to my other HIV/AIDS drugs, subcutaneous injections have not" limited ADL. Over 75 percent of patients agreed with each of the statements that moderate activities (96 percent), preparing meals (95 percent), vigorous activities (91 percent), family life (89 percent), social relationships (87 percent), performance of work (78 percent) and intimacy (76 percent) had not been affected by the treatment regimen.

More About the Substudy

When asked about issues of refrigeration, reconstitution and disposal of needles, patients rated each procedure on a scale of one (very difficult) to five (very easy), with mean scores of 3.8, 3.4 and 4.4, respectively. Of patients completing 48 weeks of treatment, 98 percent stated that, if offered, they would choose to continue with twice-daily subcutaneous injections of T-20. Of those patients who withdrew prematurely for any reason, 85 percent would have chosen to continue treatment with T-20.

In addition, over half of patients agreed with each of the statements that subcutaneous injections had not affected the general performance of daily activities (62 percent), personal appearance (62 percent), health privacy (62 percent) or ability to travel (54 percent).

T20-205 was a Phase II, open-label, single-arm clinical trial conducted to assess the safety of T-20 via twice-daily subcutaneous injection in combination with other anti-HIV drugs in patients with extensive prior treatment experience and who had previously received T-20 in other studies. Of the 70 patients treated with T-20, 97 percent had been previously treated with a protease inhibitor and 79 percent had been treated with all three existing classes of antiretrovirals. Patients had received an average of over nine prior anti-HIV drugs.

The most common adverse event related to T-20 in the T20-205 trial was injection site reactions. However, no patients discontinued due to these events. In clinical studies to date, including this trial, the most common adverse events observed with T-20 were mild to moderate in severity. The most frequent adverse events include injection site reaction, headache, nausea, fever, increased energy levels, asthenia, diarrhea, and dizziness, although a causal relationship to T-20 cannot be established for some of these events.

More About Fusion Inhibitors

This new class of investigational anti-HIV drugs known as fusion inhibitors belongs 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 enters and takes over a host cell. Classes of drugs within the entry inhibitor category include attachment inhibitors, chemokine coreceptor inhibitors and fusion inhibitors. 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.

Both T-20 and T-1249, the second-generation fusion inhibitor, 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

Hoffmann-La Roche Inc. (Roche), based in Nutley, N.J., is the U.S. prescription drug unit of the Roche Group, a leading research-based health care enterprise that ranks among the world's leaders in pharmaceuticals, diagnostics and vitamins. Roche discovers, develops, manufactures and markets numerous important prescription drugs that enhance people's health, well-being and quality of life. Among the company's areas of therapeutic interest are: dermatology; genitourinary disease; infectious diseases, including influenza; inflammation, including arthritis and osteoporosis; metabolic diseases, including obesity and diabetes; neurology; oncology; transplantation; vascular diseases; and virology, including HIV/AIDS and hepatitis C.

For more information on the Roche pharmaceuticals business in the United States, visit the company's Web site at: http://www.rocheusa.com.

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, which also inhibits HIV fusion, has received fast-track designation from the FDA and is in Phase I/II clinical testing.

For more information on Trimeris, Inc., visit the company's Web site at www.trimeris.com.

Trimeris Safe Harbor Statement

Note: Except for any historical information presented herein, matters presented 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.