>>RICHMOND, Calif., Dec. 13 /PRNewswire-FirstCall/ -- Onyx Pharmaceuticals, Inc. (Nasdaq: ONXX - News) today announced the presentation of preclinical data showing the ability of ONYX-411, a second-generation therapeutic virus, to specifically deliver anticancer gene products to tumors following systemic (intravenous) administration. The presentation was given today by Yuqiao Shen, Ph.D., senior scientist of Onyx Pharmaceuticals at the 11th International Conference on Gene Therapy of Cancer in San Diego, California.
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"We believe these results provide compelling in vivo evidence that ONYX-411, an adenovirus engineered to selectively replicate in tumors with mutations in the retinoblastoma (RB) pathway, can be used as a safe and efficient vector for the delivery of gene products to the tumor," said Leonard Post, Ph.D., Onyx senior vice president, research and development. "Onyx' proprietary technology for inserting the therapeutic gene into the vector is designed to ensure that the gene is expressed only when the virus replicates. Since the virus is designed to replicate only in tumors, the gene expression is restricted to the tumors. Using this technology, we believe we can increase the cancer-killing properties of our viruses while minimizing the effect on healthy cells, even after intravenous administration."
In his presentation, Dr. Shen described experiments in which ONYX-443 was administered intravenously to immunodeficient mice carrying human tumor xenografts. ONYX-443 is an Armed Therapeutic VirusTM product constructed by modifying ONYX-411 to express a gene that makes the enzyme cytosine deaminase (CD). CD converts a non-toxic prodrug (5-fluorocytosine, or 5-FC) into a highly toxic chemotherapeutic agent (5-fluorouracil, or 5-FU). Dr. Shen reported that strong expression of CD was detected only in tumors, not in liver or other normal tissues, following the systemic administration of ONYX-443. Moreover, during time course studies (five days post-virus injection until 24 days post-injection in some experiments), CD expression in tumors increased with time, presumably due to the continuous replication and spread of the virus. Expression of CD appeared to correlate with virus replication in vivo.
"We believe this technology opens up the possibility for intravenous delivery of cancer gene therapy, an important development since it will allow treatment of metastatic disease beyond the tumors that can be targeted by local administration," added Dr. Post.<<
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Cheers, Tuck |
