Continuing efforts to convert from gene-hunter to profitable drug marketer, Human Genome Sciences Inc. of Rockville has selected as its new chairman a former senior executive of two major pharmaceutical companies.

Argeris N. Karabelas, a Human Genome Sciences board member, will become chairman Oct. 17, the company said yesterday. He will replace William A. Haseltine, who in March announced plans to retire this year as chairman and chief executive.

The company is still searching for a chief executive.

Haseltine, who made major discoveries about the AIDS virus before founding Human Genome Sciences in 1992, has said his research skills are not what the company needs at the top to compete in the marketplace. Late-stage development and marketing skills are in order, he said.

Karabelas was chief executive of worldwide pharmaceuticals for Novartis AG from 1998 to 2000. Before that, he spent most of his career at SmithKline Beecham PLC, where he was vice president of U.S. marketing and president of North American pharmaceuticals. He holds a PhD in pharmacokinetics, the study of how drugs interact with the body.

Human Genome Sciences also promoted Craig A. Rosen from president of research and development to president and chief operating officer.

Rosen, who has been running the company's day-to-day operations, did not rule out his candidacy for chief executive, but said: "There are many qualified candidates in the company that could be CEO, not only myself. But I fully endorse the search. Just as [Haseltine] didn't have late-stage development experience, neither do I. That's what we're looking for first."

Karabelas will lead the chief executive search, Rosen said. Karabelas was traveling and not available for comment, a company spokesman said.

Human Genome Sciences, which lost more than $185 million last year, has yet to market a drug, suffering two notable failures. The company has several products in advanced human testing, including treatments for lupus, rheumatoid arthritis, cancer and hepatitis.

"What we really have here is a company that is focused on product development and really driving these things to market," said Edward A. Tenthoff, an analyst with Piper Jaffray Cos.

Human Genome Sciences also said that Laura D'Andrea Tyson will retire from the board to devote more time to the London Business School, where she is dean.

Company shares, which trade on Nasdaq, closed yesterday at $12.71, up a penny.