Founder of Amgen Increases Ownership Share in Icos

George Rathmann, the founder of Amgen Inc., the Thousand Oaks biotechnology concern, has increased his ownership in another biotech firm, Bothell, Wash.-based Icos Corp.

Rathmann, who is Icos’ chairman, along with Microsoft Corp. founder William Gates bought about half the Icos shares available in a special offering last month.

The two executives, who are among Icos’ largest shareholders, acted independently.

Rathmann raised his stake to about 7.8% from 6.5%. Gates doubled his holdings to 15% of Icos.

One of Icos’ top products, an antibody aimed at treating multiple sclerosis, is in the early stages of clinical trials.

The company is also working on anti-inflammatory drugs to help people suffering from rheumatoid arthritis and asthma.

In addition, Icos has a joint research venture with Glaxo Holdings PLC, a London-based pharmaceutical firm.

Icos raised $23.3 million in last month’s stock sale. Rathmann and Gates exercised their rights to the stock after other shareholders declined.

Rathmann stepped down from Amgen several years ago and planned to retire. But he was bored and decided to get involved in another start-up biotechnology company.