Atlanta, Georgia, USA / Leiden, The Netherlands, 9 April 2008 - Dutch biotechnology company Crucell N.V., the Aeras Global TB Vaccine Foundation and the South African Tuberculosis Vaccine Initiative (SATVI) present a progress update and immunology data from a Phase I Ad35 tuberculosis vaccine study at the biennial "Tuberculosis Vaccines for the World" conference (Atlanta, Georgia, April 9 to 11) today. The study, conducted in Worchester, South Africa and launched in May 2007, is the second phase I study in a current series of three and has revealed promising results.

Highest CD8 immune responses ever in a TB vaccine study
Preliminary data show both critical arms of the cellular immune system, CD4 and CD8 immune T-cells were induced and that in those participants who responded, CD8 immune responses are considerably higher than has ever previously been seen in a TB vaccine study.

The trial of AERAS-402/Crucell Ad35, which began in May 2007, is being conducted as a double-blind, randomized, placebo-controlled dose escalation study in four groups of healthy adults vaccinated at birth with BCG (Bacille Calmette-Guérin) vaccine. A total of 40 healthy adult volunteers are enrolled.

"While preliminary, these results are promising. We are pleased that Crucell's technologies are playing a key role in the search and development of a much-needed TB vaccine," said Dr. Jaap Goudsmit, Chief Scientific Officer at Crucell. "We highly value the collaboration with Aeras and SATVI on this important mission."

Third key clinical phase I study in progress
Aeras and Crucell began jointly developing this vaccine candidate in 2004 using Crucell's AdVac® vaccine technology and PER.C6® manufacturing technology. A first Phase I clinical trial launched in October 2006 in Kansas, USA indicated that the vaccine candidate is safe in healthy adults in the US. The results of a second study, launched in May 2007, are presented in Atlanta at the 'TB Vaccines for the World' conference. A third phase I study in healthy adults in St. Louis, Missouri, USA was launched in December 2007 and focuses on the immunogenicity and safety of two AERAS-402/Crucell Ad35 boost doses administered at three to six month intervals after BCG priming in healthy adults.

"The world urgently needs a new TB vaccine, and although we are still in the early stages of clinical trials, the preliminary data of this second phase I study are promising," said Dr. Jerald C. Sadoff, President and CEO of Aeras. "Aeras is delighted to be working with the excellent researchers at Crucell and SATVI. We are grateful to the Bill and Melinda Gates Foundation, the Netherlands Ministry of Foreign Affairs, and our other donors for their financial support of this trial and our vaccine development efforts."

This trial was conducted in the Boland-Overberg region of Western Cape Province in South Africa, which has one of the world's highest TB burdens.

"SATVI is proud to be playing such an important role in the global effort to develop new vaccines to combat TB, which are needed in South Africa and worldwide," said Prof. Gregory Hussey, Director of SATVI and Principal Investigator for the trial. "By conducting this trial, we have advanced the development of a new TB vaccine, expanded scientific capacity, and built awareness of the need for new TB vaccines."

About Tuberculosis
Tuberculosis is the world's second deadliest infectious disease, with over 9 million new cases diagnosed in 2006. According to the World Health Organization (WHO), an estimated 1.7 million people died from TB in 2006. One third of the world's population has been infected with the TB bacillus and current treatment takes 6-9 months. The current TB vaccine Bacille Calmette-Guérin (BCG), developed over 85 years ago, reduces the risk of severe forms of TB in early childhood, but is not very effective in preventing pulmonary TB in adolescents and adults - the populations with the highest rates of TB disease. TB is changing and evolving, making new vaccines more crucial to controlling the pandemic. Tuberculosis is now the leading cause of death for people living with HIV/AIDS, particularly in Africa. Multi-drug resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are hampering treatment and control efforts.

About AdVac® technology and Ad35
AdVac® technology is a vaccine technology developed by Crucell and is considered to play an important role in the fight against emerging and re-emerging infectious diseases, and in biodefense. The technology supports the practice of inserting genetic material from the disease-causing virus or parasite into a 'vehicle' called a vector, which then delivers the immunogenic material directly to the immune system. Most vectors are based on an adenovirus, such as the virus that causes the common cold. The AdVac® technology is specifically designed to manage the problem of pre-existing immunity in humans against the most commonly used recombinant vaccine vector, adenovirus serotype 5 (Ad5), without compromising large-scale production capabilities or the immunogenic properties of Ad5. AdVac® technology is based on adenoviruses that do not regularly occur in the human population, such as Ad35. In contrast to for instance Ad35 antibodies, antibodies to Ad5 are widespread among people of all ages and are known to lower the immune response to Ad5-based vaccines, thereby impairing the efficacy of these vaccines. All vaccine candidates based on AdVac® are produced using Crucell's PER.C6® production technology.

About PER.C6® technology
Crucell's PER.C6® technology is a cell line developed for the large-scale manufacture of biopharmaceutical products including vaccines. The production scale potential of the PER.C6® cell line has been demonstrated in an unprecedented successful bioreactor run of 20,000 liters. Compared to conventional production technologies, the strengths of the PER.C6® technology lie in its excellent safety profile, scalability and productivity under serum-free culture conditions. These characteristics, combined with its ability to support the growth of both human and animal viruses, make PER.C6® technology the biopharmaceutical production technology of choice for Crucell's current and potential pharmaceutical and biotechnology partners.

About Aeras
The Aeras Global TB Vaccine Foundation (www.aeras.org) is a non-profit organization working as a Product Development Partnership to develop new tuberculosis vaccines and ensure that they are distributed to all who need them around the world. Aeras is funded by the Bill and Melinda Gates Foundation, the Netherlands Ministry of Foreign Affairs, the Danish International Development Agency, the Research Council of Norway and the U.S. Centers for Disease Control and Prevention. Aeras, with over 110 employees, is based in Rockville, Maryland, where it operates a state-of-the-art manufacturing and laboratory facility.