Selectively replicating adenoviruses for cancer therapy: an update on clinical development.

Adenoviruses can be engineered to replicate selectively in tumor cells but inefficiently in normal cells. ONYX-015 (CI-1042, dl1520; Onyx Pharmaceuticals Inc), which replicates selectively in cells deficient in the p53 pathway, was the first such adenovirus to reach clinical testing. Multiple trials of ONYX-015 in over 300 cancer patients, and trials with other selectively replicating adenoviruses, have established the safety of this approach. Evidence of anticancer activity in patients is encouraging. Recently, the first clinical trial of a selectively replicating adenovirus carrying an inserted transgene was reported. Adenoviruses with improved efficiency of replication, technologies for use of the viruses as vectors for anticancer gene therapy, and various other approaches, provide promising directions to develop selectively replicating adenoviruses into systemic therapy for metastatic cancer.