By Charles Craig

Protein Design Labs Inc., with its most advanced product successfully through Phase III clinical trials, generated nearly $73 million in a public offering of 2.275 million shares.

The Mountain View, Calif., company, which is developing humanized monoclonal antibodies to treat a variety of diseases, sold 275,000 more shares than anticipated.

In addition to the stock offered by Protein Design, a corporate partner, Corange International Ltd., sold 750,000 shares for $24 million, reducing its ownership to about 9.33 percent.

When Protein Design registered for its first follow-on offering since going public in 1992, the company proposed selling 2 million shares and its stock (NASDAQ:PDLI) was trading at $34 per share. Following the stock sale, Protein Design will have 18.1 million shares outstanding.

Underwriters Oppenheimer & Co. Inc., Lehman Brothers and PaineWebber Inc., all of New York, have options to buy another 453,750 shares to cover overallotments.

Protein Design ended Wednesday at $32, down $0.125.

The company's leading drug candidate, Zenapax, is under development with Roche Holding Ltd., of Basel, Switzerland, for prevention of kidney transplant rejection. The monoclonal antibody binds to the interleukin-2 receptor on T cells to inhibit their proliferation and prevent the transplant host's immune system from attacking the donor organ.

Last month Protein Design and Roche reported positive data from two multinational Phase III trials of Zenapax, and the companies have said they expect to file for FDA marketing approval in the first half of this year. (See BioWorld Today, Feb. 4, 1997, p.2, and Feb. 19, 1997, p.1.)

Bermuda-based Corange subsidiary Boehringer Mannheim GmbH, of Mannheim, Germany, is working with Protein Design on development of three monoclonal antibodies for treating hepatitis and cytomegalovirus and preventing tissue damage resulting from trauma-induced inflammation. A fourth antibody is targeted for an undisclosed cardiovascular indication.

Protein Design also is conducting its own Phase II/III trials of a monoclonal antibody for treatment of acute myeloid leukemia.

In addition to drug development, Protein Design is using its technology to humanize mouse monoclonal antibodies for other biotechnology and pharmaceutical firms. So far the company has six collaborations. Customers pay for antibody humanization, which prevents the mouse-generated antibody from neutralization by the human immune system, and for rights to market the antibodies. For each antibody, Protein Design gets $1 million up front, additional funds for achievement of development milestones, and royalties.

Protein Design has been issued broad patents in the U.S. and Europe covering not only the humanization technology but also use of the antibodies.

To date two companies that developed their own humanized monoclonal antibodies have licensed Protein Design's patents to market their drugs.

Protein Design officials have said as many as 18 monoclonal antibodies currently in clinical trials may be covered by the company's patents.

Protein Design ended 1996 with $99.7 million in cash and reported a net loss of $11.8 million for the year. *