First Milestone Achieved in Collaboration Agreement with Sanofi Pasteur

LEIDEN, The Netherlands | March 31, 2008 | Dutch biotechnology company Crucell N.V. today announced that its rabies monoclonal antibody combination has entered a Phase II clinical trial in the United States. At the beginning of the year, Crucell announced it had signed a collaboration and commercialization agreement with sanofi pasteur, the vaccines division of sanofi-aventis Group, for Crucell’s rabies monoclonal antibodies to be used in combination with sanofi pasteur rabies vaccine for post-exposure prophylaxis against this fatal disease. The start of the Phase II study constitutes the first milestone in this agreement.

The clinical trial will be a randomized, single-blind, controlled study in 140 healthy volunteers that will test the antibody product in association with sanofi pasteur rabies vaccine and compare it to the currently marketed human rabies immune globulin or placebo, in association with rabies vaccine. The main parameters under investigation will be safety, tolerability and (rabies virus) neutralizing activity.

"We are very pleased with our continued and rapid progress with this next generation rabies treatment," said Ronald Brus, Crucell’s Chief Executive Officer. "The swift development of this rabies monoclonal antibody product would be extremely valuable in reducing the global burden of this fatal disease."

Sanofi Pasteur is the worldwide market leader in providing biologicals for pre- and post-exposure prophylaxis against rabies. In the last 20 years, over 20 million people in 100 countries have been treated with sanofi pasteur’s rabies products.

About rabies

Rabies is a viral disease of mammals most often transmitted through the bite of a rabid animal. The virus infects the central nervous system, causing encephalitis (inflammation of the brain) and ultimately death if medical intervention is not sought promptly after exposure. There is no proven treatment for rabies once symptoms of this fatal disease have appeared. Rabies is prevented by post-exposure prophylaxis (PEP) with the combined administration of a rabies vaccine and rabies immunoglobulin (RIG). Rabies is prevalent in Europe, Asia, Africa, North America and South America. Every year approximately 10 million people are vaccinated against the disease worldwide. An estimated 40,000 to 70,000 people die from rabies each year, mainly in Asia.

About Crucell’s rabies monoclonal antibody program

Crucell’s rabies monoclonal antibody product is a combination of two human monoclonal antibodies, generated using Crucell’s MAbstract® technology and produced using Crucell’s PER.C6® technology. Crucell’s rabies monoclonal antibody combination offers the potential to replace the traditional serum-derived products that are currently used for rabies post-exposure prophylaxis. Phase I clinical trials conducted in the United States and India demonstrated safety and the ability to protect. The antibody combination is well tolerated, provides the expected virus neutralizing activity and can be safely administered in association with a rabies vaccine. The program has been granted a Fast Track designation by the Food and Drug Administration’s (FDA) Department of Health and Human Services. The Fast Track program facilitates the development and expedites the review of new drugs that are intended to treat serious or life-threatening diseases and that demonstrate the potential to address unmet medical needs.

In December 2007, Crucell and sanofi pasteur signed an exclusive collaboration and commercialization agreement for Crucell’s rabies monoclonal antibodies, next-generation rabies biologicals, to be used with sanofi pasteur rabies vaccine for post-exposure prophylaxis against this fatal disease. Under the terms of the agreement, Crucell will continue to perform the development activities. Crucell will be responsible for the manufacturing of the final product and will retain exclusive distribution rights in Europe, co-exclusive distribution rights in China and the rights to sell to supranational organizations such as UNICEF. Crucell received an initial payment of €10 million following the execution of the agreement and will be eligible for milestone payments of up to €66.5 million.

Peak sales for Crucell’s rabies antibody combination are expected to exceed US$ 300 million.

About PER.C6® technology

Crucell’s PER.C6® technology is a cell line developed for the large-scale manufacture of biopharmaceutical products such as recombinant proteins including monoclonal antibodies. The strengths of the PER.C6® technology lie in its safety profile, scalability and productivity under serum-free culture conditions.

About MAbstract® technology

Crucell’s proprietary MAbstract® technology can be used to discover drug targets, such as cancer markers or proteins from infectious agents including bacteria and viruses, and identify human antibodies against those drug targets.

About sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company, discovers, develops and distributes therapeutic solutions to improve the lives of everyone. Sanofi-aventis is listed in Paris (EURONEXT: SAN) and in New York (NYSE: SNY).

Sanofi Pasteur, the vaccines division of sanofi-aventis Group, provided more than 1.6 billion doses of vaccine in 2007, making it possible to immunize more than 500 million people across the globe. A world leader in the vaccine industry, sanofi pasteur offers the broadest range of vaccines protecting against 20 infectious diseases. The Company’s heritage, to create vaccines that protect life, dates back more than a century. Sanofi pasteur is the largest company entirely dedicated to vaccines. Every day, the company invests more than EUR 1 million in research and development. For more information, please visit: www.sanofipasteur.com or www.sanofipasteur.us.

About Crucell

Crucell N.V. (Euronext, NASDAQ: CRXL; Swiss Exchange: CRX) is a global biotechnology company focused on research, development, production and marketing of vaccines, proteins and antibodies that prevent and treat primarily infectious diseases. Its vaccines are sold in public and private markets worldwide. Crucell’s core portfolio includes a vaccine against hepatitis B, a fully-liquid vaccine against five important childhood diseases and a virosome-adjuvanted vaccine against influenza. Crucell also markets travel vaccines, such as the only oral anti-typhoid vaccine, an oral cholera vaccine and the only aluminum-free hepatitis A vaccine on the market. The Company has a broad development pipeline, with several product candidates based on its unique PER.C6® production technology. The Company licenses its PER.C6® technology and other technologies to the biopharmaceutical industry. Important partners and licensees include DSM Biologics, sanofi-aventis, Novartis, Wyeth and Merck & Co. Crucell is headquartered in Leiden, the Netherlands, with subsidiaries in Switzerland, Spain, Portugal, Italy, Sweden, Korea and the US. The Company employs over a 1000 people. For more information, please visit www.crucell.com.

Forward-looking statements

This press release contains forward-looking statements that involve inherent risks and uncertainties. We have identified certain important factors that may cause actual results to differ materially from those contained in such forward-looking statements. For information relating to these factors please refer to our Form 20-F, as filed with the U.S. Securities and Exchange Commission on June 13, 2007, and the section entitled "Risk Factors". The Company prepares its financial statements under generally accepted accounting principles in the United States (US GAAP) and Europe (IFRS).

SOURCE: Crucell