RetroNectin^®, the company's proprietary recombinant protein of human fibronectin, has been widely used for retroviral gene therapy protocols as it significantly enhances retrovirus-mediated gene transfer to mammalian cells.
As an alternative application of RetroNectin^® for therapeutic purposes, the company discovers its potential use in adoptive immunotherapy for cancer. Peripheral blood T cells stimulated and expanded in vitro on immobilized RetroNectin^® in the presence of anti-CD3 monoclonal antibody and IL-2, contain approximately 2 fold higher numbers of naïve T-like cells over T cells expanded without RetroNectin^®. Naïve T cells have high potential of antigen recognition and are able to live for a long time in vivo.
Furthermore, cytotoxic T lymphocytes (CTLs) induced from T cells expanded on immobilized RetroNectin^® show two-folds higher cytotoxic activity against tumor cells over ones from T cells expanded by conventional method. These findings were presented at 65^th annual meeting of the Japanese Cancer Association which is being held from 28 September to 30 September 2006 in Yokohama.

Immunotherapy with T cells is expected to be one of the most promising alternative treatment for cancer and infectious diseases. In contrast to the conventional cancer therapy including chemotherapy, radiation therapy, and surgery, the immunotherapy has advantages of higher specificity as well as lower burden for the patients. Current studies of adoptive transfer of tumor-reactive T cells to cancer patients involve the infusion of T cells that have been stimulated and expanded in vitro. However, T cells expanded by current cell culture technologies have limited replicative capacity and therefore cannot provide long-term protection from the diseases.
The company has previously reported that peripheral blood T cells could be efficiently expanded on immobilized RetroNectin^® in the presence of anti-CD3 monoclonal antibodies and IL-2 at 62^th annual meeting of the Japanese cancer association, 2003. The company's subsidiary, Takara Biomedical Technology (Beijing) Co., Ltd., applied to Beijing Drug Administration for permission to begin clinical trials of adoptive immunotherapy for renal cancer using RetroNection^® in partnership with the Cancer Institute and Hospital, Chinese Academy of medical science.

The present study demonstrates that T cells expanded on immobilized RetroNectin^® contain higher numbers of naïve T cell populations having CD45RA⁺CCR7⁺ cell surface marker. Once naïve T cells are stimulated by antigen presenting cells in secondary lymphoid organs near the tumor site, they can be expanded having tumor-specific CTLs activities even though they don't have tumor-specificity before induction. In addition, the new data confirms that tumor-specific CTLs induced from T cells expanded on immobilized RetroNectin^® has superior cytotoxic activity against tumor cells to T cells expanded by conventional method, suggesting RetroNectin^®-expanded T cells can support long-term and potent anti-cancer activity in vivo.

The Company expects that this novel expansion method can be also applied to other immunotherapy strategies including "Cancer vaccine therapy" as well as "Dendritic cell vaccine therapy", contribute to advance the successful launch of "Cancer Immunotherapy" in real world.

About Takara Bio Inc.
Takara Bio Inc. is an innovative biotechnology company based in Shiga, Japan. As a world leader in biotechnology research and development, Takara Bio was the first company to market PCR technology in Japan and is also the developer of the RetroNectin^® reagent, which is a world-standard in gene therapy protocols. In addition to providing research reagents and equipment to the life science research market, Takara Bio has active research and product development activities in the fields of gene and cell-based therapy, and agricultural biotechnology; and is committed preventing disease and improving the quality of life for all people through the use of biotechnology. Through strategic alliances with other industry leaders, the Company aims to extend its reach around the world. More information is available at http://www.takara-bio.com.

For more information:
Corporate Communications
Takara Bio Inc.
E-mail: bio-ir@takara-bio.co.jp

This article is translated from press release in Japanese for your convenience.

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