ThromboGenics and BioInvent Have Dosed the First Patient in Phase IIb Trial of TB-402 (Anti-Factor VIII) for Venous Thromboembolism (VTE) Prophylaxis

Trial to Assess the Benefits of Partial Factor VIII Inhibition in Total Hip Replacement Surgery Patients

LEUVEN, Belgium and LUND, Sweden, April 27, 2011 - ThromboGenics NV (Euronext Brussels: THR) and co-development
partner BioInvent International (OMXS: BINV) announce today that the first
patient has been dosed in a Phase IIb trial with their novel long-acting
anticoagulant TB-402 (Anti-Factor VIII) for the prophylaxis of venous
thromboembolism (VTE) after total hip surgery.

The Phase IIb study is a multicenter, double blind, randomised
controlled trial. It is comparing the safety and efficacy of two dose levels
of TB-402, given as a single intravenous infusion after hip surgery, with the
recently approved Factor Xa inhibitor rivaroxaban. The trial will enrol 600
patients across 41 centers in Europe. Results are expected in the second half
of 2012.

TB-402 is a recombinant human monoclonal antibody that has a
novel mode of action. It targets Factor VIII, a key component of the
coagulation cascade. An important benefit of TB-402 is that a single
injection could provide a stable, long-acting antithrombotic effect, for the
prophylaxis of VTE after orthopaedic surgery, which is expected to lead to
reduced nursing time and improved patient compliance.

Importantly, TB-402's anti-coagulant activity is easily
reversible using Factor VIII, in case of bleeding or need for surgery. In
contrast, certain newer anticoagulant therapies lack an antidote which can
make it difficult to manage serious bleeds or which may complicate or delay
acute surgical procedures.

In 2010, TB-402 reported positive results in a 315-patient
Phase IIa trial for VTE prophylaxis after knee replacement surgery, compared
with enoxaparin, the standard treatment for preventing VTE in this setting.
The positive pooled results of three doses of TB-402 (0.3 mg/kg, 0.6 mg/kg
and 1.2 mg/kg) showed a 22% incidence of total VTE compared with 39% for
enoxaparin (p<0.05). In addition, TB-402 was generally well tolerated and
demonstrated comparable safety to enoxaparin. The results were published in
the Journal of Thrombosis and Haemostasis in February 2011[1].

Dr. Patrik De Haes, CEO of ThromboGenics, commenting on the
announcement said: "TB-402 has already shown the potential to significantly
improve the treatment of VTE in the post-surgery setting. We hope that this
study will confirm these promising results and give us a better understanding
of the overall benefits that TB-402 can provide to this patient group. We
believe that VTE prophylaxis with a single dose of TB-402 that lasts for
several weeks is a simple and attractive option for physicians and patients
when compared with other anticoagulant regimes that are currently available."

Svein Mathisen, CEO of BioInvent, added: "We are delighted
about the product's demonstrated success in earlier trials and believe that
it represents an innovative approach to the prevention of VTE after hip
orthopaedic surgery. TB-402 promises to become a very important entrant into
the anticoagulant market where the product would fill a significant unmet
need."

About TB-402

TB-402 has the potential to be an important new entrant into
the anticoagulant market. TB-402 is a long-acting agent, which means it could
be given as a single dose to prevent the development of VTE 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. Importantly, this could lead to
better patient compliance. 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, as well as the need for anticoagulation
monitoring. These are the two main drawbacks associated with current
anticoagulant therapy.

About Venous Thromboembolism (VTE)

VTE is the third most common cardiovascular disease after
myocardial infarction and stroke.[2] It includes both deep vein thrombosis
(DVT) and pulmonary embolism (PE). DVT is caused when a blood clot forms in a
deep vein, most commonly in the deep veins of the lower leg. PE occurs when a
blood clot blocks the main artery of the lung or one of its branches. DVT and
PE are major public health issues. It is estimated that in the US alone, more
than 600,000 patients are treated for venous thromboembolisms such as DVT or
PE each year.[3] Moreover, DVT and PE together may be responsible for more
than 100,000 deaths in the US each year.[4]

It is estimated that by 2015, 1.4 million patients will
undergo knee replacement and 600,000 patients will undergo hip replacement in
the US if current trends persist.[5] 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. 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.

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 ocriplasmin
(microplasmin) has completed two Phase III clinical trials for the
pharmacological treatment of symptomatic vitreomacular adhesion (sVMA).
Ocriplasmin is also being evaluated in Phase II clinical development for
additional vitreoretinal conditions. ThromboGenics is also developing novel
antibody therapeutics in collaboration with BioInvent International; these
include TB-402 (anti-Factor VIII), a long-acting anticoagulant in Phase II,
and TB-403 (anti-PlGF) in Phase Ib/II for cancer in partnership with Roche.

ThromboGenics is headquartered in Leuven, Belgium. The Company
is listed on NYSE 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 to strengthen the product pipeline and
increase the likelihood of success. These partners include Genentech, Human
Genome Sciences, Roche and ThromboGenics.

The company's competitive position is underpinned by an in
substance patented antibody development platform. The scope and strength of
this platform is also utilised by partners, such as Bayer HealthCare, Daiichi
Sankyo, Mitsubishi Tanabe, UCB and XOMA.

More information is available at www.bioinvent.com.

Important information about forward-looking statements

Certain statements in this press release may be considered
"forward-looking". Such forward-looking statements are based on current
expectations, and, accordingly, entail and are influenced by various risks
and uncertainties. The Company therefore cannot provide any assurance that
such forward-looking statements will materialize and does not assume an
obligation to update or revise any forward-looking statement, whether as a
result of new information, future events or any other reason. Additional
information concerning risks and uncertainties affecting the business and
other factors that could cause actual results to differ materially from any
forward-looking statement is contained in the Company's Annual Report.

———————————

[1] "Single Intravenous Administration of TB-402 for the Prophylaxis of
Venous Thromboembolism After Total Knee Replacement: A Dose-Escalating,
Randomised, Controlled Trial", Peter Verhamme, MD, Marco Tangelder, MD,
Raymond Verhaeghe, MD, Walter Ageno, MD, Steven Glazer, MD, Martin Prins, MD,
Marc Jacquemin, MD, Harry Büller, MD, JTH.

[2] The role of oral direct thrombin inhibitors in the prophylaxis of
venous thromboembolism", Hawkins D, Pharmacotherapy, October 24, 2004;
10 Pt 2, pp.179S-183S.

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

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

[5] "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

    Dr. Steve Pakola, CMO                    Tel: +1(212)201-0920
                                             steve.pakola@thrombogenics.com

    Dr. Patrik De Haes, CEO                  Tel: +32-16-75-13-10
                                             patrik.dehaes@thrombogenics.com

    Citigate Dewe Rogerson

    David Dible/Nina Enegren/Sita Shah       Tel: +44(0)207-638-95-71
                                             nina.enegren@citigatedr.co.uk

    BioInvent International AB

    Svein Mathisen, President & CEO          Tel: +46(0)46-286-85-67
                                             svein.mathisen@bioinvent.com

    Cristina Glad, Executive Vice President  Tel: +46(0)46-286-85-51
                                             cristina.glad@bioinvent.com

    College Hill (media enquiries)

    Melanie Toyne Sewell, Anastasios Koutsos Tel: +44(0)20-7866-7856
                                             bioinvent@collegehill.com

    Rebecca Skye Dietrich                    Tel: +1-857-241-0795
                                             bioinvent@collegehill.com

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