Chiron Announces Phase III Clinical Trial Evaluating

Proleukin(R) In Combination With HIV Therapy Emeryville, Calif. (ots-PRNewswire) - Trial to Establish the Role of Proleukin(R) in Delaying the Progression Of AIDS in HIV- Infected Patients. Chiron Corporation (Nasdaq: CHIR) announced today that it is enrolling patients in its international Phase III study, called SILCAAT, evaluating the safety and effectiveness of Proleukin(R) (aldesleukin) Interleukin-2 in combination with standard anti-HIV therapy in people living with HIV with low CD4+ T-cell counts. Proleukin, a recombinant form of Interleukin-2, also known as T- cell growth factor, is being administered in combination with anti-HIV therapy in people with HIV infection. This pivotal study's primary objective is to determine if intermittent cycles of Proleukin delay the progression of HIV disease compared to what is observed with anti-HIV therapy alone in people with advanced HIV infection. "Using Proleukin to augment the immune system is a novel approach in the treatment of HIV. Current anti-HIV therapies target the virus specifically, while Proleukin is designed to bolster and help rebuild the compromised immune system," said Lewis T. (Rusty) Williams, M.D., Ph.D., Chiron's chief scientific officer and president of research and development. "Based on promising preliminary data, we believe that Proleukin in conjunction with anti-HIV therapy may offer people with HIV an improved clinical benefit over current therapies alone." The hallmark of HIV infection is a progressive decrease and functional impairment of CD4+ T-cells, which can cause the body to become more susceptible to the opportunistic infections and malignancies associated with AIDS. Phase II studies involving people with HIV infection have shown that Proleukin in combination with standard anti-HIV therapy produced increases in CD4+ T-cell counts and an improvement in other immune function parameters that appear to be sustained over the course of one year. The most common side effects reported in the studies of Proleukin in people with HIV infection were injection site reaction (i.e., redness or bumps), a flu-like syndrome, edema, rashes, joint and muscle pain, oral discomfort, anorexia and insomnia. Most of these effects improved after the five-day course of Proleukin therapy was completed. "Advances in anti-HIV treatments clearly have improved the length and quality of life of HIV-positive people. However, in some people, the degree of immune reconstitution and control of the virus is incomplete," said Yves Levy, M.D., Hospital Henri Mondor in Paris and principal investigator of SILCAAT worldwide. "This Phase III trial will help define the potential added benefits of Proleukin when combined with anti-HIV therapies and answer the question of whether Proleukin can augment the immune system, resulting in a delay of HIV disease progression." Chiron's international Phase III clinical trial, SILCAAT (Phase III Multicenter Randomized Study of Subcutaneous Recombinant, Human Interleukin-2 in HIV-Infected People with Low CD4+ Counts Under Active Antiretroviral Therapy), will enroll an estimated 1,400 people at more than 100 sites worldwide. "With the breadth of Phase II research illustrating Proleukin's ability to increase CD4+ T-cell counts and improve the immune status in most people with HIV, we are excited to be conducting this large, multicenter, international Phase III trial," said Anne-Marie Duliege, M.D., a director of clinical research and clinical development at Chiron. "We hope this study will establish Proleukin's long-term clinical benefits, enabling Chiron to offer people with HIV a unique addition to current treatment options." Enrollment Criteria People enrolled in the trial will be randomized into one of two treatment groups, receiving either Proleukin plus anti-HIV therapy, or anti-HIV therapy alone. Researchers will assess the time to the first AIDS-defining event (illness associated with AIDS) as the primary endpoint, with variations in CD4+ T-cell counts, changes in viral load and occurrence of adverse events as other important endpoints. People eligible to enroll in the study are those who have: * HIV infection; * CD4+ T-cell counts between 50 and 300; * Viral load < 10,000 RNA copies/mL; * Been on a stable regimen of at least two anti-HIV therapies for at least four months. Chiron Corporation was granted a license to market Proleukin for the treatment of metastatic melanoma (advanced skin cancer) in the United States in January 1998 and for the treatment of metastatic renal cell carcinoma (advanced kidney cancer) in the United States in 1992, in Canada in 1994 and in Europe in 1989. Chiron Corporation, headquartered in Emeryville, California, is a leading biotechnology company that participates in three global healthcare markets: biopharmaceuticals, vaccines and blood testing. The company is applying a broad and integrated scientific approach to the development of innovative products for preventing and treating cancer, infectious diseases and cardiovascular disease. This approach is supported by research strengths in recombinant proteins, genomics, small molecules, gene therapy and vaccines. This news release may contain forward-looking statements regarding Proleukin and its effect on patients with HIV. Actual results could differ materially from those described in this news release as a result of a number of factors, including, but not limited to the following: There can be no assurance that final results of human clinical trials will be supportive of regulatory approvals required to market products, or that final regulatory approval will be received in a timely manner, if at all, or that any product in the Chiron product pipeline will be successfully developed or manufactured, or that patient and physician acceptance of these products will be achieved, nor can there be any assurance as to the impact of competitive products or other market conditions. These and other factors investors should consider are more thoroughly discussed in the company's filings with the Securities and Exchange Commission, including the Form 10-K and Form 10-Q. Chiron does not undertake any obligation to revise or update the statements in this press release to reflect events or circumstances after the date of this release. NOTE: Proleukin is a registered trademark of Chiron Corporation. Product information may be obtained on the Internet at www.chiron.com or by calling 800-chiron8. ots Original Text Service: Chiron Corporation Internet: http://www.newsaktuell.de Contact: Julie Wood of Chiron Corporation, (USA) 510-923-6686; or Philip N. Swayze of Ketchum Public Relations, (USA) 415-984- 2284, for Chiron Corporation Web site: http://www.chiron.com Subscribers please note that material bearing the slug "PROTEXT" is not part of CTK's news service and is not to be published under the "CTK" slug. Protext is a commercial service providing distribution of press releases from clients, who are identified in the text of Protext reports and who bear full responsibility for their contents.