By Randall Osborne

The FDA Tuesday cleared for sale Amgen Inc.'s hepatitis C drug, Infergen, and the company is making the product available immediately.

"It's already being shipped," said Amgen spokesman David Kaye.

Infergen (interferon alfacon-1) is a consensus alpha interferon, different from the natural protein, and is administered three times per week by subcutaneous injection. Until recently, interferon alfa-2a and interferon alfa-2b were the only approved therapies for hepatitis C, but many patients treated with them failed to respond or relapsed. Subjects in a clinical trial showed improvement with larger doses of Infergen.

Amgen, of Thousand Oaks, Calif., pits Infergen, the company's third product, against Intron-A (interferon alfa-2b), marketed by Schering-Plough Corp., of Madison, N.J., and Roferon-A (interferon alfa-2a), which is copromoted by Gilead Sciences Inc., of Foster City, Calif., and Roche Holding Ltd., of Basel, Switzerland.

"Schering has the lion's share of the hepatitis C interferon market," Kaye said. "We recognize that, and we've got a competitive sales force ready to go."

Barbara Hoffman, an analyst with Vector Securities International Inc., of Deerfield, Ill., said the market for Infergen is "relatively small" and predicted "modest" sales.

"The issue for Amgen investors is near-term earnings outlook: this year, next year and 1999," Hoffman said.

None of Amgen's dozen or so products in the pipeline will provide large earnings in the period, she said. "You'll see Stemgen [Amgen's stem-cell factor for use in cancer patients undergoing chemotherapy] approved next year, and that will be marginally additive," Hoffman said. "Infergen will be marginally additive."

Schering is the exclusive licensee of an interferon patent granted in 1985 to Biogen Inc., of Cambridge, Mass. In December 1996, Schering sued Amgen, charging patent infringement. The lawsuit is pending.

"The big market for interferon is overseas," Hoffman said, especially in Japan. Amgen has licensed to Yamanouchi, a Tokyo-based pharmaceutical company, the rights to develop, manufacture and commercialize consensus interferon outside the U.S. and Canada. In 1994, Biogen filed a patent-infringement lawsuit there, too, and it is still pending.

Hoffman said she holds out more hope for Amgen's megakaryocyte growth and development factor, a blood-platelet booster in Phase II trials. It could be given to healthy donors to enrich their platelets in an effort to reduce the number of donations given to cancer patients undergoing chemotherapy. An abstract to be presented later this month at the American Association of Blood Banks meeting shows a low-dose injection of the factor increased platelet counts by 1.76-fold to 2.36-fold, which held for a "prolonged duration" with no adverse events reported.

Amgen's other drugs are Epogen, a red-cell booster for treatment of anemia in kidney dialysis patients, and Neupogen, which is used to replenish white blood cells destroyed by cancer chemotherapy.

Amgen's stock (NASDAQ:AMGN) closed Tuesday at $49.437, up $1.75, a 3.67 percent jump. *