ThromboGenics and BioInvent Announce Positive Topline Results From Phase II VTE Prophylaxis Study With Anti-Factor VIII (TB-402)

TB-402 Demonstrates Superior Antithrombotic Activity to Enoxaparin

LEUVEN, Belgium and LUND, Sweden, May 6, 2010 - ThromboGenics NV (Euronext Brussels: THR) and co-development
partner BioInvent International (OMXS: BINV) announce today positive results
from their Phase II trial of TB-402. TB-402 is a novel, long acting
anticoagulant that is being developed as a single injection for the
prevention of venous thromboembolism (VTE) following orthopaedic surgery. The
Phase II results demonstrate that TB-402 has superior antithrombotic activity
to enoxaparin (Lovenox(R): sanofi-aventis) with comparable safety. Enoxaparin
is currently the standard treatment to prevent VTE in this setting. Venous
thromboembolism encompasses both deep venous thrombosis (DVT) and pulmonary
embolism (PE).

The Phase II trial was a multicenter, dose-escalating,
randomised, open-label trial, evaluating TB-402 against enoxaparin for the
prophylaxis of VTE after knee surgery. All patients received enoxaparin 40mg
pre-operatively. Post operatively, patients were randomized in a sequential
cohort design to one of three doses of TB-402 (0.3mg/kg, 0.6mg/kg or
1.2mg/kg) or enoxaparin 40mg (3:1; n=75 per group).

TB-402 was administered as a single intravenous bolus
injection 18-24 hours after orthopaedic surgery, whereas enoxaparin was given
as a 40mg subcutaneous injection once daily for a period of at least 10 days.
The primary efficacy endpoint was based on measuring all occurrences of VTE
in patients by Day 7-11, whether they were symptomatic or asymptomatic. The
primary safety endpoint was the number of patients with major or clinically
relevant non-major bleeding from randomisation until the end of the study at
3 months. The study enrolled a total of 316 patients across 30 centers in
Europe.

For the pooled TB-402 treated group, 47 out of 218 (or 22%)
patients experienced VTE; for the enoxaparin treated group, 30 out of 77 (or
39%) patients experienced VTE (p<0.05). The difference of reduction between
the two groups is statistically significant.The study also showed that TB-402
and enoxaparin had a similar safety profile.

The results of this trial ("Single intravenous administration
of TB-402 for the prophylaxis of VTE after total knee replacement surgery")
will be presented by Prof. Peter Verhamme (University of Leuven, Belgium) at
the 21st International Congress on Thrombosis in July in Milan, Italy.

Patrik De Haes, CEO of ThromboGenics, commented, "It is very
clear that VTE is a major clinical problem that carries considerable costs
both to patients and healthcare providers. These exciting results show that
TB-402 when given as a single post-operative injection could dramatically
reduce the incidence of VTE. This would clearly be a major step forward in
preventing this potentially life threatening condition. These results also
reinforce our confidence that we can secure a significant partnership deal
that will allow us to bring TB-402 to market and deliver its significant
potential."

Svein Mathisen, CEO of BioInvent, also commented, "We are
delighted with the progress of TB-402 and are excited about the product's
demonstrated success over current treatments in preventing VTE in
post-operative patients and the associated advantages of this being delivered
as a single dose. These results underpin our belief that this novel approach
will find a solid place in the anticoagulation market."

About TB-402

TB-402 has the potential to be a very important new entrant
into the anticoagulant market. TB-402 is a recombinant human monoclonal
antibody that partially inhibits Factor VIII, a key component of the
coagulation cascade. This novel mode of action is expected to reduce the risk
of undesirable bleeding events, even at high doses, as well as the need for
patient monitoring. These are the two main drawbacks associated with current
anticoagulant therapy. In addition, TB-402 is a long-acting agent, which
means it could be given as a single dose to prevent the development of DVT in
patients undergoing surgery. This simple approach to prophylaxis would be an
attractive option, as all current anticoagulant treatment options require
daily treatment for up to several weeks.

About Deep Vein Thrombosis (DVT)

DVT is caused when a blood clot forms in a deep vein, most
commonly in the deep veins of the lower leg. DVT is a major public health
issue and it is estimated that in the U.S. alone, more than 600,000 patients
are treated for venous thromboembolisms (VTE) such as DVT or pulmonary
embolism (PE) each year.[1] Moreover, DVT and PE together may be responsible
for more than 100,000 deaths in the U.S. each year.[2]

It is estimated that by 2015, 1.4 million patients will
undergo knee replacement and 600,000 patients will undergo hip replacement in
the U.S. if current trends persist.[3] Patients undergoing hip replacement or
knee surgery are particularly at risk of developing DVT and all patients are
therefore treated with anticoagulants prophylactically in order to reduce the
risks of blood clots. The annual sales of anticoagulants worldwide are over
$5 billion. Nevertheless, available anticoagulants are still inconvenient and
associated with an increased risk of bleeding. Improved anticoagulants are
therefore required. In particular, agents that allow for improved ease of
administration (without requirement for daily dosing and frequent dose
adjustment) would fill a significant unmet need.

Legal disclaimer

This press release contains statements about the future,
consisting of subjective assumptions and forecasts for future scenarios.
Predictions for the future only apply as of the date they are made and are,
by their very nature, in the same way as research and development work in the
biotech segment, associated with risk and uncertainty. With this in mind, the
actual outcome may deviate significantly from the scenarios described in this
press release.

Notes to Editors:

About ThromboGenics

ThromboGenics is a biopharmaceutical company focused on the
discovery and development of innovative medicines for the treatment of eye
disease, vascular disease and cancer. The Company's lead product microplasmin
is in Phase III clinical development for the non-surgical treatment of back
of the eye diseases. Microplasmin is also being evaluated in Phase II
clinical development for additional vitreoretinal conditions. In addition,
ThromboGenics is developing novel antibody therapeutics in collaboration with
BioInvent International; these include TB-402 (anti-Factor VIII), a long
acting anti-coagulant, and TB-403 (anti-PlGF) for cancer.

ThromboGenics is headquartered in Leuven, Belgium. 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 NASDAQ OMX Stockholm
(BINV), is a research-based pharmaceutical company that focuses on developing
antibody drugs. The Company currently has four clinical development projects
within the areas of thrombosis, cancer and atherosclerosis. The Company has
signed various strategic alliances around these product candidates and is
developing them in collaboration with partners including Genentech, Roche and
ThromboGenics.

These projects are based around a competitive and in substance
patented antibody development platform. The scope and strength of this
platform is also utilised by partners, such as ALK-Abello, Bayer HealthCare,
Daiichi Sankyo, ImmunoGen, Mitsubishi Tanabe Pharma Corporation, OrbusNeich,
UCB and XOMA. More information is available at www.bioinvent.com.

———————————

[1] Barclays Capital Equity Research Report on New Anticoagulants, August
5, 2009

[2] "The Surgeon General's Call to Action to Prevent Deep Vein Thrombosis
and Pulmonary Embolism," September 15, 2008, p.1.

[3] "Changes in Surgical Loads and Economic Burden of Hip and Knee
Replacements in the US: 1997-2004," Sunny Kim, Arthritis & Rheumatism
(Arthritis Care & Research), April 15, 2008; 59:4, pp. 481-488.

    For further information, please contact:

    ThromboGenics NV
    Patrik De Haes, MD
    Chief Executive Officer
    Tel : +32(0)16-75-13-10
    E-mail: patrik.dehaes@thrombogenics.com

    Andy De Deene, MD
    Clinical Director Europe
    Tel: +32(0)16-75-13-10
    E-mail: andy.dedeene@thrombogenics.com

    Citigate Dewe Rogerson
    Amber Bielecka, David Dible, Nina Enegren
    Tel: +44(0)207-638-95-71
    E-mail: amber.bielecka@citigatedr.co.uk

    BioInvent International AB
    Svein Mathisen
    President & CEO
    Tel: +46(0)46-286-85-67
    Mobile: +46(0)708-97-82-13
    E-mail: svein.mathisen@bioinvent.com

    Cristina Glad
    Executive Vice President
    Tel: +46(0)46-286-85-51
    Mobile: +46(0)708-16-85-70
    E-mail: cristina.glad@bioinvent.com

    College Hill (media enquiries)
    Holly Griffiths, Sue Charles, John McIntyre
    Tel: +44(0)20-7866-7856
    E-mail: bioinvent@collegehill.com

    ThromboGenics NV
    Gaston Geenslaan 1
    B-3001 Leuven
    Belgium
    Tel: +32(0)16-75-13-10
    www.thrombogenics.com

    BioInvent International AB (publ)
    Co. reg. No. 556537-7263,
    Address: Solvegatan 41
    Mailing address: SE-223 70 LUND
    Tel: +46(0)46-286-85-50
    info@bioinvent.com

    www.bioinvent.com

For further information, please contact: ThromboGenics NV, Patrik De Haes, MD, Chief Executive Officer, Tel : +32(0)16-75-13-10, E-mail: patrik.dehaes at thrombogenics.com; Andy De Deene, MD, Clinical Director Europe, Tel: +32(0)16-75-13-10, E-mail: andy.dedeene at thrombogenics.com; Citigate Dewe Rogerson, Amber Bielecka, David Dible, Nina Enegren, Tel: +44(0)207-638-95-71, E-mail: amber.bielecka at citigatedr.co.uk; BioInvent International AB, Svein Mathisen, President & CEO, Tel: +46(0)46-286-85-67, Mobile: +46(0)708-97-82-13, E-mail: svein.mathisen at bioinvent.com; Cristina Glad, Executive Vice President, Tel: +46(0)46-286-85-51, Mobile: +46(0)708-16-85-70, E-mail: cristina.glad at bioinvent.com; College Hill (media enquiries), Holly Griffiths, Sue Charles, John McIntyre, Tel: +44(0)20-7866-7856, E-mail: bioinvent at collegehill.com