PBL Therapeutics has been issued U.S. Patent No. 6,514,753 entitled "Expression Vectors for Producing Modified Proteins," which covers genetically engineered systems that can be used to produce radiolabeled proteins that selectively target and kill cancer cells.

"There are several monoclonal antibody-based cancer drugs on the market today generating over $2 billion in revenues. One hundred more are in clinical trials," said Robert Pestka, president and chief executive officer of PBL Therapeutics. "We have an enormous opportunity to improve the safety and cancer-killing effectiveness of these drugs with our phosphorylation technology, which we are commercializing with the help of a recent grant from the National Cancer Institute."

The company's phosphorylation technology, used primarily to radiolabel therapeutic monoclonal antibodies (MAbs), significantly improves upon the chemical labeling procedures currently used to target radiation to tumors. MAbs with genetically engineered phosphorylation sites facilitate the delivery of high-energy radiophosphate to cancer cells. These radiophosphorylated MAbs retain higher activity and selectivity for tumor antigens and appear less immunogenic than MAbs radiolabeled through conventional chemical conjugation methods. In addition, the use of radiophosphate effectively confines the radioactivity to the patient, nearly eliminating the exposure of health care workers and patient family members to the potentially harmful radioactive emissions common to other radioisotopes.