By Mary Welch

Abgenix Inc. plans to raise about $273 million by selling up to 1.8 million shares of its common stock, and another 700,000 shares owned by Cell Genesys Inc. and worth about $105 million also are being offered.

In addition, the underwriters have the option to purchase another 375,000 shares, of which 270,000 shares would be from Abgenix and 105,000 from Cell Genesys. The offering is being managed by BancBoston Robertson Stephens Inc., Lehman Brothers Inc., and Merrill Lynch & Co., all of New York, and Pacific Growth Equities Inc., of San Francisco.

Abgenix is in a SEC-declared "quiet period" and could not discuss the filing, said Kurt Leutzinger, Abgenix' vice president and chief financial officer.

After the sale, Cell Genesys, of Foster City, Calif., will own about 14.1 percent of Abgenix. Abgenix currently has 17.2 million shares outstanding.

The company will use the proceeds for a variety of purposes, including building a manufacturing facility, possible acquisitions as well as funding clinical trials. The Fremont, Calif., company currently has four antibody product candidates under internal development, three of which are in human trials.

Those three candidates are: ABL-CBL, ABX-IL8, and ABX-EGF. ABL-CBL is in Phase III trials for steroid-resistant graft-vs.-host disease. ABX-CBL is a monoclonal antibody that binds to the protein CD147, which is upregulated on certain activated immune cells. It works when it attaches to the CD147 antigen, then signals other immune cells to destroy the targeted cell. (See BioWorld Today, Dec. 9, 1999, p. 1.)

ABX-IL8 is in Phase I/II trials for psoriasis while ABX-EGF is in Phase I for various epidermal growth factor receptor-dependent cancers.

The success of Abgenix's stock price was responsible for the killing of a proposed merger between Cell Genesys and Genzyme General, of Cambridge, Mass, in a deal initially valued at $350 million. At the time, Cell Genesys owned 22 percent of Abgenix, and its value of the equity ownership increased more than $230 million since the merger was announced in October and stopped in December. (See BioWorld Today, Oct. 19, 1999, p. 1; and Dec. 22, 1999, p. 1.)

Abgenix' stock (NASDAQ:ABGX) closed Friday at $146.625, down $16.375.