By Mary Welch

In a deal worth potentially $200 million, Corixa Corp., and SmithKline Beecham Plc, of London, entered into a major expansion of their original 1995 tuberculosis vaccine collaboration. The two companies now will seek antigen discoveries in several indications, including two new ones.

"This deal supersedes all the previous agreements we have had with Corixa, "said Moncef Slaoui, vice president of business development for SB Biologicals SA, of Rixensart, Belgium, which is the center of all SmithKline's activities in the field of vaccine research, development and production.

The deal is worth $49 million in SmithKline funding to Corixa over the next four years, including a purchase of $2.5 million worth of Corixa common stock. Corixa may also require SmithKline to buy another $2.5 million more in stock at a later date. In addition, Corixa could receive more than $150 million in product milestones (excluding royalties) payable upon successful clinical development and commercialization of any products. The $150 million figure also excludes milestones and royalties on possible non-vaccine products potentially available to SmithKline under the program, such as monoclonal-antibody-based therapeutics.

"It is by far our biggest collaboration to date," said Mark McDade, chief operating officer for Seattle-based Corixa. "It's a subtle transition for the company. We began as an antigen-discovery company only looking at tuberculosis. Now we are looking at a number of new diseases and vaccine antibodies."

The new deal calls for antigen discovery efforts aimed at the development of vaccines for two chronic infectious pathogens, Chlamydia trachomatis, which causes sexually transmitted diseases, and Chlamydia pneumoniae, which has been associated with the development of atherosclerosis. In addition, the agreement allows for the selection of one additional field to be agreed upon later.

The two companies originally joined up in October 1995 in a deal worth about $22 million to find antigens for a tuberculosis vaccine. Corixa has received about $6 million so far from that arrangement.

In March 1997, the two again hooked up to seek antigen vaccines for breast and prostate cancer. At that time, SmithKline took out an option for ovarian and colon cancer. Financial terms were not disclosed but SmithKline agreed to pay research funding, milestone payments and royalties on future products in exchange for worldwide rights. This August, the two extended this tuberculosis pact and funding through May 1999 and SmithKline retained its exclusive option to license any discovered antigens in the TB program through August 1999. (See BioWorld Today, Aug. 10, 1998, p. 1.)

As part of this new deal, SmithKline exercise its option for ovarian and prostate cancer.

In addition, SmithKline has licensed rights to Corixa's Her-2neu vaccine for breast and ovarian cancer, currently in Phase I trials, as well as Corixa's breast cancer antigen, mammaglobin. Under the umbrella deal all vaccine rights, with one exception, are worldwide and exclusive to the London-based SmithKline. The exception is for tuberculosis vaccine rights in Japan, which Corixa and SmithKline share in a co-exclusive arrangement.

Corixa's stock (NASDAQ:CRXA) closed Wednesday at $5.062, up $0.75. *