Chiron Submits Biological License Application For Proleukin - RECOMBINANT IL-2 - For Treatment of Metastatic Melanoma.

EMERYVILLE, Calif.--(BUSINESS WIRE)--April 14, 1997--Chiron Corporation (NASDAQ:CHIR) announced today that it has submitted a supplemental Biological License Application (sBLA) to the United States Food and Drug Administration (FDA), seeking clearance to market Proleukin (aldesleukin, recombinant interleukin-2 (IL-2)) for injection to treat patients with metastatic melanoma.

The sBLA is based on clinical studies performed at 19 institutions in the United States. Steven A. Rosenberg, M.D., Ph.D., and his associates at the National Cancer Institute (NCI) pioneered this work and contributed 147 patients to the 270 patients involved in the trials of Proleukin. Proleukin currently is marketed by Chiron for the treatment of metastatic renal cell carcinoma, and received Orphan Drug Status for the treatment of metastatic melanoma in September 1996.

The incidence of melanoma, an aggressive form of skin cancer, has tripled over the last four decades and is increasing at a faster rate than any other cancer. While melanoma strikes people of all ages, its incidence is rising most rapidly in people under age 40, and it is the most commonly occurring cancer in women between the ages 25 to 29. In the U.S., approximately 40,000 new cases of melanoma were diagnosed, and an estimated 7,300 deaths occurred that were attributable to the disease in 1995. The median survival time for patients with Stage IV, or metastatic melanoma, where the cancer has spread to other parts of the body, including the lungs, brain, or bone, is approximately seven months. While these patients can benefit from aggressive therapy, current treatment options such as surgery, chemotherapy and radiation have had limited clinical utility. Various combination regimens using chemotherapy and immune-enhancing biological agents, including IL-2, are currently under investigation.

"We believe that Proleukin immunotherapy represents a significant advance in therapeutic options for the treatment of metastatic melanoma," said Bruce F. Scharschmidt, M.D., vice president, Clinical Affairs, Chiron Technologies. "Clinical studies performed to date have demonstrated that IL-2 as single-agent therapy can produce durable responses, where some patients have remained disease free for eight years or more. These are clinically impressive results in a deadly disease where the patient prognosis is often only a few months," said Scharschmidt.

The toxicity of Proleukin therapy was severe, manageable and rapidly reversible in most cases. However, these effects were rarely chronic or cumulative.

Chiron currently is supporting clinical research using biochemotherapy regimens of IL-2 administered in combination with chemotherapy and alpha interferon to treat metastatic melanoma.

In March 1996, the FDA implemented a new policy, "Reinventing the Regulation of Cancer Drugs," to expand access to promising therapies for the treatment of cancer. As a part of this initiative, the FDA is facilitating the clinical study of previously approved drugs for new cancer uses, and is encouraging the submission of supplemental applications for secondary cancer indications. Under this policy, the FDA plans to accelerate the regulatory review of drugs that demonstrate safety and efficacy in these new indications to expedite the time to marketing approval for a wide range of cancer therapeutics.

"We applaud the FDA's efforts to expand the array of therapeutic options available for the treatment of cancer," said Magnus Lundberg, president of Chiron Therapeutics. "The clinical evidence of Proleukin's therapeutic risk benefit in treating metastatic melanoma support the submission of this sBLA. We plan to work closely with the FDA to review and, as appropriate, expand Proleukin's use in this and other new indications where it has shown promising results."

While the precise mechanism of action of IL-2 is unknown, research suggest that it activates and enhances the immune systems cancer fighting properties. Specifically, IL-2 stimulates the growth of lymphokine-activating killer (LAK) cells and natural killer (NK) cells that are able to kill cancer cells, as well as cytokines such as gamma interferon which are tumoricidal at the site of metastases.

Because of IL-2's broad immunomodulatory effect, as demonstrated by its efficacy in both metastatic renal cell carcinoma and metastatic melanoma, Chiron is investigating Proleukin's potential utility in additional indications for cancer and infectious disease. IL-2 is currently being evaluated in clinical studies in the U.S. and abroad for a number of cancers, including non-Hodgkin's lymphoma and acute myelogenous leukemia (AML).

Chiron Corporation, headquartered in Emeryville, Calif., near San Francisco, is a science-driven, market-directed healthcare company that combines diagnostic, vaccine and therapeutic strategies for controlling disease. Chiron participates in four global healthcare markets: diagnostics, including immunodiagnostics, critical care diagnostics and new quantitative probe tests; therapeutics, with an emphasis on oncological, infectious, neurological and cardiovascular disease; pediatric and adult vaccines; and ophthalmic surgical products for the correction of vision. Chiron also conducts research and development in the fields of biological proteins, gene therapy and combinatorial chemistry.

CONTACT: Chiron Corporation

Larry Kurtz, 510/923-2476

or

Kimberly Sankaran, 510/923-2412