New Conditionally Replicating Adenovirus Vectors for Breast Cancer Therapy

摘要

There is a pressing need to develop new treatments for breast cancer. Oncolytic, conditionally-replicating adenoviruses (CRADs) represent one such approach. Our objective to develop new CRADs containing mutant DNA polymerases with a high functional dNTP requirement; we hypothesize that these vectors will replicate selectively in tumor cells. We have identified an important surrogate for the adenovirus DNA polymerase (Ad pol): the thermostable DNA polymerase of Pyrococcus furiosus (Pfu) and we have completed a characterization of Pfu DNA polymerase that has resulted in the identification of conserved amino acid residues that affect dNTP binding and utilization. We have mutated these and other residues within Ad pol, and then introduced these mutations into an infectious molecular clone of Ad5. These studies have shown that conservative Ad pol mutations with modest effects on dNTP utilization are compatible with adenovirus replication and recovery of infectious virus (I664V, I664M, M689V, and a S928L/C687S double mutant). In contrast, less conservative mutations and mutations with more profound effects on the dNTP binding efficiency of the adenovirus DNA polymerase give rise to replication-defective viruses. In year 3 (a no-cost extension period), we will test whether these viruses can selectively replicate in, and kill, breast cancer cells.