November 11, 2003

Altor BioScience today announced the recent online publication in Cancer Immunology, Immunotherapy of research studies which support the Company’s approach for using soluble T-cell antigen receptor (STAR™) fusions as targeted therapeutics for cancer.

The publication demonstrates that fully active STAR fusions can be generated that consists of a tumor antigen targeting T-cell receptor (TCR) linked to the anti-cancer drug, IL-2. The TCR used in this fusion was chosen based on its ability to specifically bind a peptide antigen of the human p53 tumor suppressor protein, which is over-expressed in a broad range of human malignancies. Altor strategy is use the binding activity of this TCR to deliver cytokines, such as IL-2, to the tumor site and stimulate the immune system to stop tumor growth or spread. In this study, Altor scientists found that the STAR fusion protein exhibits favorable pharmacokinetics and substantially increases the half-life of the IL-2 portion of the molecule. Altor’s collaborators at the Florida Hospital Cancer Institute in Orlando, Florida showed that the fusion protein was capable of reducing lung metastases in an experimental model for metastasis. The fusion protein was further shown to detectably stain human tumor cells suggesting the utility of these reagents in cancer diagnosis or imaging.

Commenting on the publication, Hing Wong, Ph.D., CEO of Altor, said: “The results of this study represents a major breakthrough in demonstrating for the first time that soluble TCR-based reagents are active in blocking tumor growth in vivo. This report is just the first in a series of preclinical efficacy studies Altor has completed to advance the STAR therapeutics into human clinical trials. In addition, the ability of these reagents to specifically bind novel antigens on tumors and other cells opens up a number of possibilities for their use in cancer screening and biomarker detection for diseased and infected cells.”

About STAR™

Unlike monoclonal antibodies that only bind secreted or cell-surface proteins, TCRs can recognize a broad range of targets derived from both intercellular and extracellular proteins. This provides TCR-based reagents an advantage as the next-generation targeted therapeutics for cancer and viral infection. Altor’s proprietary STAR™ technology allows the specific TCR targeting activity to be incorporated into readily produced, soluble and stable reagents. This technology also provides a means for delivering cytotoxic drugs, radioisotopes and immunomodulatory agents directly to novel antigen targets on viral infected or cancerous cells. For more information, visit www.altorbioscience.com.

This work was supported in part by a Phase I SBIR grant awarded to Altor BioScience by the National Cancer Institute.