Production of novel proteins therapeutics for cancer treatment

Abstract

Antibody-directed enzyme prodrug therapy (ADEPT) is a novel strategy to improve the selectivity of cancer treatment. ADEPT is a two-step approach that seeks to generate a potent cytotoxic agent selectively at a tumor site. In the first step, a tumor-selective antibody is chemically linked to an enzyme such as glucarpidase and then administered intravenously. In the second step, a relatively non-toxic prodrug is administered. By this time, the antibody conjugate has been cleared from the blood and other tissues. Methotrexate (MTX), a synthetic folate analogue that inhibits dihydrofolate reductase, a key enzyme in the folate pathway, serves as an important component of various chemotherapeutic regimens for the treatment of cancer patients. One major drawback to the clinical use of MTX is an unacceptable level of toxicity. One of the most effective ways to achieve a rapid removal of the excess of these drugs is by glucarpidase degradation. Repeated cycles of ADEPT and the use of wild type glucarpidase in detoxification are essential but are hampered by the human antibody response to the enzyme. Additionally, glucarpidase has a relatively slow action in detoxification. We implemented a state-of-the-art technique, DNA shuffling, to overcome the problems associated with this technology. We successfully produced an ultra-active glucarpidase that degrades MTX with a very high efficency and we are continuing the production of more efficient forms. We also isolated and performed a molecular charaterisation on a novel glucarpidase which could be used in the ADEPT techniques for cancer treatment that could overcome the antibody problems.