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Fred Hutchinson Cancer Research Center and Targeted Genetics announces issuance of broad patent covering antigen-specific T cell expansion

Targeted genetics receives exclusive license to technology

SEATTLE -- Fred Hutchinson Cancer Research Center (FHCRC) and Targeted Genetics Corporation (Nasdaq: TGEN) announce that they have received notification from the U.S. Patent and Trademark Office regarding the issuance of patent #5,827,642 entitled " Rapid Expansion Method ("REM") for in vitro Propagation of T Lymphocytes."

The patent covers technology used to expand antigen-specific T cells for use in adoptive immunotherapy techniques, which has the potential to treat diseases such as cancer as well as viral infections. This technology was developed by Stanley R. Riddell, M.D., and Philip D. Greenberg, M.D., Ph.D., researchers in the Hutchinson Center's Clinical Research Division and professors at the University of Washington. Greenberg is also a member of Targeted Genetics' Scientific Advisory Board. The Hutchinson Center has exclusively licensed this technology to Targeted Genetics.

"Adoptive immunotherapy represents a potentially powerful tool in the treatment of infectious disease and cancer," says Riddell. "Previous studies have demonstrated that T lymphocytes play a crucial role in eliminating virally infected or cancerous cells from the body. However, clinical application of adoptive immunotherapy has been difficult because the technology to expand antigen-specific cells while retaining function has not been readily available. The REM technology enables the production of sufficient numbers of cells capable of eliminating infected or malignant cells to make adoptive immunotherapy a viable therapeutic approach."

Researchers at Targeted Genetics and the Hutchinson Center have leveraged the REM technology to develop methods for genetically modifying cytotoxic T cells (CTL) to enhance their function by providing key proteins that may be lacking in certain disease settings, such as AIDS. Additionally, REM expansion modified CTLs could be used to deliver cytokines to diseased target cells without the toxicities observed when cytokines are administered systemically.

Targeted Genetics has supported two Phase I studies of HIV-specific CTLs in HIV infected patients conducted by Riddell and Greenberg at the Hutchinson Center. Additional Phase I/II studies of adoptive immunotherapy using CTLs expanded with the REM technology are ongoing at the Hutchinson Center for the precaution of cytomegalovirus (CMV) disease in bone marrow transplant patients and for the treatment of patients with late stage melanoma

Targeted Genetics has several issued and pending patents in this area. Prior to development of the REM technology, technical and regulatory hurdles made adoptive immunotherapy too costly for commercialization. Targeted Genetics has further developed this technology to facilitate commercial development by focusing on scalability of costs and reagents. Targeted Genetics has filed additional patents regarding improvements to the REM technology.

"In addition to its significant potential in adoptive immunotherapy, Targeted Genetics' REM technology also is a strategic core technology for research, development, and commercialization of other technologies aimed at treating chronic viral and malignant disease," said H. Stewart Parker, President and Chief Executive Officer of Targeted Genetics. "The REM process is applicable to broad-based technologies such as genomics and to the identification of new proteins or small molecules with therapeutic potential. This patent, in concert with Targeted Genetics' other patents and intellectual property, forms a powerful core technology platform either as a stand alone therapeutic or in concert with existing technologies."

Targeted Genetics Corporation develops gene and cell therapy products for the treatment of certain acquired and inherited diseases. The company has three lead development programs targeting cystic fibrosis, cancer, and infectious diseases as well as an extensive gene delivery and cellular therapy technology platform.

The Fred Hutchinson Cancer Research Center is an independent, non-profit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. Recognized internationally for its pioneering work in bone marrow transplantation, the Center has four scientific divisions collaborating to form a unique environment for conducting basic and applied science. One of 35 National Cancer Institute-designated comprehensive cancer centers in the country, it is the only one in the Northwest.


Adoptive Immunotherapy Background

The human body is bombarded daily with infectious agents and potentially cancer-causing DNA damage. Normally, these assaults do not lead to chronic diseases such as cancer or hepatitis but usually cause an acute, self-limited disease that is resolved within a matter of days. The cellular immune system is responsible for keeping these assaults in check. The cellular immune system is comprised of two subsets of T cells: CD4+ T helper cells and CD8+ cytotoxic T cells (CTLs). Targeted CTLs recognize and eliminate virally infected or malignantly transformed cells. Activation and expansion of targeted CTLs requires a complex set of cellular interactions including cytokines and other factors produced by antigen-specific CD4+ helper T cells. Chronic viral infection or cancer occurs when these assaults overwhelm the ability of CTLs to eliminate diseased cells. Adoptive immunotherapy is a process in which researchers remove a small amount of blood from the patient and isolate the very small number of CTLs specific for the disease present in the patient. Once isolated, these cells are expanded to numbers (billions) necessary to combat the overwhelming disease burden in the patient. These targeted CTLs are then infused into the patient to cure or contain the disease. Animal models of current expansion technologies result in only a seven to 10 fold increase in cell number in a seven to 10 day period and require reagents not available for human use. Targeted Genetics' REM technology overcomes these hurdles for treating human disease, allowing billions of cells to be produced in less than two weeks.

The majority of therapies on the market or under development for chronic viral and malignant disease act to stimulate a targeted CTL response (therapeutic vaccines) or manage disease burden (protease inhibitors) in an effort to stimulate in vivo expansion of the patients' own targeted CTLs. Targeted Genetics is the only company developing direct approaches to harness the power of the immune system via the REM technology. Application of the REM technology to adoptive immunotherapy may enable the potential of this approach to be realized.



David M. Schubert
Targeted Genetics Corporation
(206) 521-7809

Susan Edmonds
Fred Hutchinson Cancer Research Ctr
(206) 667-2896

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