By Charles Craig

Chiron Corp. submitted a supplemental marketing application Monday to the FDA for clearance of Proleukin for treatment of metastatic melanoma, a deadly form of skin cancer that is diagnosed in 40,000 new patients each year.

Chiron, of Emeryville, Calif., has marketed Proleukin, which is recombinant interleukin-2 (IL-2), for treatment of metastatic kidney cancer since 1992.

Larry Kurtz, Chiron's vice president of corporate communications, said data supporting the company's supplemental biological license application with the FDA demonstrating Proleukin's effectiveness in treating metastatic melanoma is similar to benefits seen in kidney cancer patients.

Clinical studies used to support Proleukin's label's expansion involved 270 patients, some of whom participated in trials conducted by the National Cancer Institute of the National Institutes of Health.

While the response rate is not high, the studies showed, patients who do fully respond to IL-2 have survived, disease free, seven years or more.

The median survival of people with Stage IV melanoma, which has metastasized throughout the body, typically is seven months. Current treatments include surgery, chemotherapy and radiation.

Chiron seeks approval of Proleukin as a single-agent therapy for melanoma, but Kurtz said ongoing clinical studies that show when the drug is used in combination with alpha interferon and chemotherapy, response rates increase.

Side effects of Proleukin can be severe, such as fluid build-up in lungs, but the adverse events are described as manageable.

Chiron officials said IL-2's mechanism of action is not known, but the protein is a cytokine that has been shown to stimulate proliferation of immune system T cells, which attack infections and cancer. IL-2 also is believed to activate other cytokines, such as gamma interferon, which destroy tumor cells.

Because the drug boosts T cells, Proleukin is being studied as a treatment for HIV as well as cancer. In a recent National Institutes of Health-sponsored study of IL-2 in combination with antiviral compounds, Proleukin showed AIDS patients experienced increases in T cells without an overall jump in amount of HIV. (See BioWorld Today, March 25, 1997, p.1.)

Chiron also is studying Proleukin for treatment of ovarian cancer, acute myelogenous leukemia and non-Hodgkin's lymphoma.

For 1996, the company reported $64 million in sales of Proleukin and other oncology drug products. That figure does not include revenues from Aredia (pamidronate disodium), which Chiron co-promotes with partner Novartis AG, of Basel, Switzerland.

Chiron's stock (NASDAQ:CHIR) closed Monday at $18.562, up $0.438. *