Novel anti-PlGF antibody, TB-403, being developed by ThromboGenics and BioInvent for cancer expected to enter the clinic later this year

LEUVEN, Belgium and LUND, Sweden | November 2, 2007 | ThromboGenics NV (Euronext Brussels:

THR), a biotechnology company focused on vascular disease, and co¬development partner, BioInvent International (Nordic Exchange: BINV), announce today the publication of data in Cell1 that highlight for the first time the therapeutic potential of anti-PlGF agents to treat cancer based on research performed at the University of Leuven, Belgium and the Flanders Institute for Biotechnology (VIB). The data published in Cell show that antibodies against PlGF (placental growth factor) can inhibit cancer tumour growth and the development of metastases in preclinical models, without affecting healthy tissues. These attractive properties are due to PIGF inhibitors acting by blocking the formation of new blood vessels only in the cancer tissue.

ThromboGenics and BioInvent have made the decision to advance their lead anti-PIGF monoclonal antibody, TB-403, into the clinic, and expect to start the first Phase I clinical trial by the end of 2007.
In particular, preclinical data showed that anti-PlGF antibodies could:

— Inhibit tumour growth and the development occurrence of tumour metastases

— Inhibit tumour growth with a distinct but complementary mechanism to currently available anti-angiogenic therapy

— Not induce resistance because it does not evoke an “angiogenic rescue” by the tumour, in contrast to current angiogenesis inhibitors

— Enhance the sensitivity of tumours to anti-VEGF

— Amplify anti-tumour effect of chemotherapy

— Not cause or aggravate the typical side effects of anti-angiogenic antibodies when given as combination therapy.

Therefore, anti-PlGF antibodies, such as TB-403, potentially have an improved efficacy/toxicity profile that would be expected to inhibit angiogenesis in diseased conditions, without, importantly, affecting normal blood vessels in healthy tissues.

These findings pave the way for the development of a new class of improved cancer therapeutics which could have a complementary mechanism of action and potentially enhanced safety profile in comparison to existing angiogenesis inhibitors.

Angiogenesis inhibitors are therapeutic agents that work by blocking the development of new blood vessels, thereby depriving growing cancer tumour cells of oxygen and nutriments. This approach in turn is thought to stop the tumour from growing and spreading to other parts of the body. Currently available angiogenesis inhibitors specifically target vascular endothelial growth factor (VEGF), which plays an important role in promoting the formation of blood vessels. However, since VEGF inhibitors also act on healthy tissue, their therapeutic potential is hampered by side effects. Although PlGF is a homologue of VEGF, it does not affect normal, physiological angiogenesis and is only involved in the angiogenesis process which takes place in the diseased tissue.

Based on its anti-angiogenic properties, ThromboGenics and BioInvent also intend to develop TB-403 for eye diseases, to block uncontrolled blood vessel growth in conditions such as age-related macular degeneration (AMD) and diabetic retinopathy.

Prof. Désiré Collen, CEO and Chairman of ThromboGenics, commented: “Today’s publication in the prestigious journal Cell clearly highlights our ground-breaking research in the field of angiogenesis. The data in the Cell paper shows the potential of our novel anti-PlGF antibody, TB-403, based on its unique ability to block the development of new blood vessels, but only via mechanisms that exist in the diseased state. This mode of action, which is different from and complementary to current anti-VEGF inhibitors, makes it attractive as both a stand-alone and combination therapy. I am very excited that we will be able to move this drug candidate into the clinic later this year, given its great therapeutic potential, not only in cancer, but also in severe eye diseases that are the major causes of blindness.”

Svein Mathisen, CEO of BioInvent, added: “The data presented in this seminal paper more fully explains the tumour inhibition findings obtained in our preclinical program to date. Through this experimental work, the development path for the collaboration partners has been clarified and the potential for TB-403, as a novel treatment for cancer, has been emphasized. I feel confident in my belief that TB-403 will secure a prominent place in the oncology armoury.”

About ThromboGenics

ThromboGenics is a biotechnology company focused on discovery and development of biopharmaceuticals for the treatment of a range of vascular diseases. The Company has several programs in Phase II clinical development including microplasmin, which is being evaluated as a treatment for vitreoretinal disorders and as a thrombolytic agent for vascular occlusive diseases, including acute stroke. ThromboGenics is also developing novel antibody therapeutics in collaboration with BioInvent International; these include TB-402 (Anti-Factor VIII), scheduled to enter Phase II clinical development in 2008, and TB-403 (Anti-PlGF), which is expected to proceed to Phase I clinical trials by the end of 2007. ThromboGenics has built strong links with the University of Leuven and has exclusive rights to certain therapeutics developed at the University. ThromboGenics is headquartered in Leuven, Belgium and has subsidiaries in Dublin, Ireland and New York, U.S. The Company is listed on Eurolist by Euronext Brussels under the symbol THR. More information is available at www.thrombogenics.com.

About BioInvent

BioInvent International AB, listed on The Nordic Exchange (OMXS:BINV), is a research-based pharmaceutical company that focuses on developing antibody drugs. The Company is currently running innovative drug projects within the areas of thrombosis, cancer, atherosclerosis and ophthalmic diseases. In January 2007, the Company announced a major strategic alliance with American-based Genentech, Inc. in the cardiovascular field. These projects are based on a competitive and in substance patented technology platform. The scope and strength of this platform is also utilised by partners, such as ALK-Abelló, ImmunoGen, OrbusNeich, Sanofi-Aventis, UCB and XOMA. The Company, which currently has 96 employees, is located at Ideon in Lund. More information is available at www.bioinvent.com.

SOURCE: ThromboGenics NV and BioInvent International