AMGEN EARNINGS ZOOM 23 PERCENT.

Byline: Dave McNary Daily News Staff Writer

Biotechnology giant Amgen Inc., continuing to post impressive results, reported Thursday a 23 percent gain in fourth-quarter earnings to $178 million, or 64 cents a share.

The results, released after the stock market closed, were a penny or two better than Wall Street analysts had expected. Sales for Thousand Oaks-based Amgen, the world's largest biotech concern, rose 16 percent to $593.5 million.

James McCamant, editor of the Medical Technology Stock Letter, said Amgen has achieved its position of prominence due to savvy marketing of its two flagship products - red-cell stimulator Epogen and white-cell booster Neupogen.

``Amgen continues to execute beautifully on the marketing side,'' McCamant said. ``The results reflect strong skills in marketing and dealing with government agencies on reimbursements for customers.''

Epogen sales rose 22 percent to $289 million while Neupogen revenues gained 10 percent to $270 million.

McCamant said the key issue for Amgen remains development of additional strong products such as a drug for treating obesity or its MGDF drug, a copy of a protein that produces platelets, which make blood clot. The fat-gene drug could be on the market by 2000 while MGDF could be sold by 1999, according to analysts.

Earlier this month, Amgen stopped a late-stage trial of a potentially blockbuster drug to treat Lou Gehrig's disease when testing showed it was ineffective.

McCamant said Amgen is likely to receive approval for its stem-cell factor drug for patients receiving chemotherapy, but added that the market for it is relatively small compared with Epogen and Neupogen.

Amgen noted Thursday that it began human trials of six potential new products last year.

For all of 1996, Amgen's earnings rose 26 percent to $680 million, or $2.42 a share, from $538 million, or $1.92 a share, in 1995. Revenues rose 15 percent to $2.24 billion.