Researchers Neutralize SARS Virus in Lab Tests

The breakthrough was accomplished using antibodies from genetically engineered mice immunized with a protein the SARS virus uses to infect cells. Researchers believe this advance may lead to treatments to prevent infection with SARS after individuals have been exposed to the virus, and potentially to therapeutic products to treat those already infected. This important progress comes just six months after the U.S. Centers for Disease Control provided the SARS virus to UMMS to launch this research.

"We believe this is a very important and very exciting breakthrough," said Donna Ambrosino, MD, Director of the MBL and a Professor of Pediatrics at the Medical School. "We've got mice producing the right antibody, so we hope it's only a matter of time before we isolate the one cell that will become the basis for a monoclonal antibody to prevent SARS in individuals exposed to the illness."

The advance came from MBL's success in producing a protein from the SARS virus that results in attachment and entry into cells. If that protein, or portions of the protein, could be blocked, it is believed that the virus would not be able to infect the host. To test the theory, the protein was introduced in specialized mice developed by Medarex that produce fully human antibodies when immunized. After immunization with the protein, the mice responded with human antibodies that bind to the protein. Sera from those mice were taken and tested against the live SARS virus in tissue culture. The antibodies in the sera neutralized the virus's ability to infect cells in the culture.

Details of the SARS research are scheduled for presentation on October 11 at the IDSA's annual meeting in San Diego by Gregory Babcock, PhD, from MBL. The SARS work at MBL is led by William Thomas, PhD, and the team at the Medical School's Worcester campus includes Thomas Greenough, MD, Katherine Ruiz de Luzuriaga, MD, Robert Finberg, MD and John Sullivan, MD. The team at Medarex includes Israel Lowy, MD, PhD, Robert Graziano, PhD and Nils Lonberg, PhD.

"We are extremely pleased with the progress that has resulted from the collaborative efforts of the scientists at MBL, UMass Medical School and Medarex," said Donald L. Drakeman, President and CEO of Medarex, Inc. "In addition, we are very appreciative of the ongoing relationships between MBL and NIH (National Institutes of Health) and CDC, which have proven beneficial to our research."

The next step in this research is to isolate the individual cell from the mice that produces the neutralizing antibody to the SARS virus. There are many cells that could be producing the right antibody and researchers at the MBL are now at work isolating cells and testing their efficacy against the SARS virus. The researchers believe that eventually the key cell will be found, cloned and a monoclonal antibody will be produced from that cell. "We hope to have a candidate cell line soon," Ambrosino said. "If all goes well, there is a chance we could have something ready for testing in people over the next two years."

As previously announced, MBL partnered with Medarex to use Medarex's UltiMAb(TM) technology to generate fully human antibodies with the potential to treat SARS. Under the terms of the agreement, Medarex and MBL expect to share equally the full development costs of any antibody products as well as any future revenues arising from these products. NIH is funding the collaboration and the initial work to discover and produce material for clinical studies.

"This productive collaboration is a good example of a private and public sector partnership to meet an urgent medical need posed by a newly emergent infectious disease," said Israel Lowy, MD, PhD, Director of Infectious Diseases at Medarex, Inc. "We believe that human monoclonal antibodies may prove to be potent therapeutic agents in a variety of infectious diseases."

SARS is a viral respiratory illness caused by a coronavirus. SARS was first reported in Asia in February 2003, and over the next few months, the illness spread to more than two dozen countries in North America, South America, Europe, and Asia. According to the World Health Organization, during the SARS outbreak of 2003, a total of 8,098 people worldwide became sick with SARS; of these, 774 died. The SARS global outbreak of 2003 was contained; however, it is expected that the disease could re-emerge in an annual cycle similar to the common flu.

"We believe that both the world health community's response to the outbreak of SARS, and the pace of progress in our efforts at the Medical School, have been outstanding," said Dr. Sullivan, director of the office of research at UMass Medical School. "Research is a painstaking process, yet in this case, things fell into place quickly. The combination of the expertise at the MBL, the ability to work with the live virus at our containment facility in Worcester, NIH support, and our partnership with Medarex that gave us access to their important technology, all made this rapid advance possible."

About UMass Medical School

The University of Massachusetts Medical School is one of the fastest growing academic health centers in the country and has built a reputation as a world-class research institution, consistently producing noteworthy advances in clinical and basic research. The Medical School attracts more than $143 million in extramural research funding annually, 80 percent of which comes from federal funding sources. Research dollars enable UMMS scientists to explore human disease from the molecular level to large-scale clinical trials. Basic and clinical research leads to new approaches for diagnosis, treatment and prevention of disease. Visit www.umassmed.edu for additional information.

About MBL

The Massachusetts Biologic Laboratories is the only non-profit FDA- licensed manufacturer of vaccines and other biologic products in the United States. The laboratory was established in 1894 and since then the MBL's mission has been to improve public health through applied research, development and production of biologic products. MBL has been a part of the UMass Medical School since 1997.

About Medarex

Medarex is a biopharmaceutical company focused on the discovery and development of therapeutics to treat life-threatening and debilitating diseases. Medarex's UltiMAb Human Antibody Development System(SM) is a unique combination of human antibody technologies that Medarex believes enables the rapid creation and development of fully human antibodies to a wide range of potential disease targets for therapeutic antibody products, including products for the treatment of cancer, inflammation, autoimmune and infectious diseases. Medarex's product pipeline is based on a variety of therapeutic antibody products developed through the use of its UltiMAb(TM) technology. Medarex creates and develops fully human antibodies for itself and others, offering a full range of antibody related capabilities, including pre-clinical and clinical development supported by cGMP manufacturing services. For more information about Medarex, visit its Web site at www.medarex.com.

For Medarex: Except for the historical information presented herein, matters discussed herein may constitute forward-looking statements that are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Statements that are not historical facts, including statements preceded by, followed by, or that include the words "potential"; "believes"; "anticipates"; "intends"; "plans"; "expects"; "estimates"; "could"; "may"; or similar statements are forward-looking statements. Medarex disclaims, however, any intent or obligation to update these forward-looking statements. Risks and uncertainties include risks associated with product discovery and development as well as risks detailed from time to time in Medarex's public disclosure filings with the U.S. Securities and Exchange Commission (SEC), including its Annual Report on Form 10-K for the fiscal year ended December 31, 2002 and subsequent Quarterly Reports on Form 10-Q. There can be no assurance that such development efforts will succeed, that such products will receive required regulatory clearance or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success. Copies of Medarex's public disclosure filings are available from its investor relations department.

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