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IL-2 SILCAAT Clinical Study Discontinued
  Chiron Corporation Provides Clinical Pipeline Update: Company Announces Discontinuation of SILCAAT and HBV-MF59 Trials And PA-1806 Program
-- Information for SILCAAT Patients and Clinicians Available Toll Free At 1-866-874-3153
EMERYVILLE, Calif., Oct. 23, 2002 /PRNewswire-FirstCall/ -- Chiron Corporation (Nasdaq: CHIR) announced today decisions on three clinical development programs. Chiron is stopping SILCAAT, a Phase III study for recombinant human interleukin-2 (IL-2, aldesleukin) in patients with HIV.
Chiron had expected to complete the SILCAAT trial, including final patient follow-up, in 2007. The company is reviewing data for a possible regulatory submission that may allow approval of IL-2 only in a subset of patients who do not achieve immunological response while on highly active antiretroviral therapies (HAART).
In addition, the company is terminating development of PA-1806, a compound for gram negative infections in cystic fibrosis patients, and HBV-MF59, an immunotherapy for patients with chronic hepatitis B infection.
"We believe our decisions will enable Chiron to more effectively invest our resources to meet unmet medical needs and to advance our core franchises in cancer and infectious disease," said Craig Wheeler, President, Chiron BioPharmaceuticals.
SILCAAT is the acronym for Chiron's international Phase III Multicenter Randomized Study of the Biological and Clinical Efficacy of Subcutaneous Recombinant, Human Inteleukin-2 in HIV-infected Patients with Low CD4 Counts Under Active Antiretroviral Therapy. The trial is an open-label study designed to compare outcomes of HIV+ persons with CD4 cell counts between 50-299/mm3 randomized to receive IL-2 (aldesleukin) in addition to antiretroviral therapy with a control group of individuals treated with antiretroviral therapy alone.
To date, Chiron has completed two scheduled interim analyses of data from the SILCAAT trial, including data from 1,000 patients followed for one year. Data from the second interim analysis of SILCAAT are consistent with results previously obtained in Phase II studies, which had shown substantial CD4 count increases and no negative effect of IL-2 on viral load. The safety of IL-2 is not a factor in Chiron's decision to discontinue SILCAAT. Data from two interim analyses of SILCAAT demonstrated that the safety of IL-2 was consistent with that seen in previous studies.
Currently 1,957 patients of a target 2,000 subjects are enrolled in SILCAAT worldwide, with 137 clinical sites in 11 countries. The primary endpoint is time to first AIDS-defining event or death. Secondary endpoints include changes (from baseline) in CD4+ cell counts and in plasma viral load. Chiron is not yet unblinded to the primary endpoint. There can be no assurance that Chiron's data package will be sufficient to support regulatory filings.
"Continued improvements in HIV treatment (i.e., HAART) have led to reduced incidence of clinical events and a decrease in the overall rate of disease progression. Since the primary endpoint for the SILCAAT trial is time to first AIDS-defining event or death, decreases in clinical events and disease progression make the duration of time required to maintain a study of this magnitude infeasible for Chiron," said Mr. Wheeler.
Chiron is currently working with the SILCAAT Scientific Committee on a transitional plan for the follow-up and management of SILCAAT patients and on approaches to maximize the scientific value of the study. For additional information, a 24-hour toll-free number has been established at 1-866-874-3153, or visit http://www.chiron.com.
PA-1806 is a Phase II program for gram negative infections in patients with cystic fibrosis. PA-1806 is a member of the beta-lactam class of antibiotics. Data from initial studies conducted by licensor Bristol-Myers Squibb (BMS) indicated that the drug had anti-bacterial activity, but side effects from intravenous administration prompted BMS to halt development.
PathoGenesis, which Chiron subsequently acquired, in-licensed the drug with a plan to reformulate it for inhaled delivery to maximize its therapeutic action. The Phase I data for PA-1806 showed satisfactory tolerability and intrapulmonary distribution, and Phase II data indicated that the compound had anti-bacterial activity. However, Chiron has halted the program due to the challenges of developing an effective inhaled formulation.
"Although PA-1806 showed acceptable anti-bacterial activity, the lack of a viable commercial formulation for the compound has led us to terminate the program," said Mr. Wheeler. "We remain committed to our inhaled antibiotic franchise and are focusing our efforts on the development of a dry-powder formulation for our TOBI product and of our PA-2794 compound."
HBV-MF59 is an immunotherapy for chronic HBV infection in Phase II trials. The study, which is being conducted at 25 sites in Asia and two in the U.S. and has enrolled about 220 subjects, is examining HBV-MF59 alone and in combination with lamivudine. No safety issues have been identified.
"Based on the results of the Phase I pilot trial, we continue to believe that this program has potential," said Mr. Wheeler. "We have worked hard to find a partner for HBV-MF59, but without success. Given the challenges of conducting a clinical trial in Asia, we have decided that we can no longer continue the program."
About Chiron
Chiron Corporation, headquartered in Emeryville, California, is a global pharmaceutical company that leverages a diverse business model to develop and commercialize high-value products that make a difference in people's lives.
The company has a strategic focus on cancer and infectious disease. Chiron applies its advanced understandings of the biology of cancer and infectious disease to develop products from its platforms in proteins, small molecules and vaccines. The company commercializes its products through three business units: biopharmaceuticals, vaccines and blood testing. For more information about Chiron, visit the company's website at http://www.chiron.com .
This news release contains forward-looking statements, including statements regarding sales growth, product development initiatives, new product marketing, acquisitions and in- and out-licensing activities that involve risks and uncertainties and are subject to change. A full discussion of the company's operations and financial condition, including factors that may affect its business and future prospects, is contained in documents the company has filed with the SEC, including the form 10-Q for the quarter ended June 30, 2002, and the form 10-K for the year ended December 31, 2001, and will be contained in all subsequent periodic filings made with the SEC. These documents identify important factors that could cause the company's actual performance to differ from current expectations, including the outcome of clinical trials, regulatory review and approvals, manufacturing capabilities, intellectual property protections and defenses, stock-price and interest-rate volatility, and marketing effectiveness. In particular, there can be no assurance that Chiron will increase sales of existing products, successfully develop and receive approval to market new products, or achieve market acceptance for such new products. There can be no assurance that Chiron's out-licensing activity will generate significant revenue, nor that its in-licensing activities will fully protect it from claims of infringement by third parties. In addition, the company may engage in business opportunities, the successful completion of which is subject to certain risks, including shareholder and regulatory approvals and the integration of operations. Consistent with SEC Regulation FD, we do not undertake an obligation to update the forward-looking information we are giving today.
SOURCE Chiron Corporation
Web Site: http://www.chiron.com
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