empty backbone vaccinia virus

The empty backbone vaccinia virus is an engineered oncolytic viral vector derived from the wild-type vaccinia virus. It has been genetically modified by the deletion of three specific viral genes: C11R (encoding vaccinia growth factor), K3L (an eIF2α homolog), and J2R (encoding thymidine kinase). These deletions are designed to restrict viral replication to cancer cells, which often have high levels of thymidine kinase and activated growth signaling pathways, thereby enhancing the safety profile and tumor selectivity of the virus. Developed by Kolon Life Science, this specific backbone serves as the foundation for the therapeutic candidate KLS-3020, which incorporates additional transgenes (PH20, sPD1-Fc, and IL-12) to boost antitumor efficacy. In preclinical models, the empty backbone itself demonstrates oncolytic activity by selectively replicating in and lysing tumor cells, though it is primarily utilized as a control or platform for further genetic enhancement.

Other names

C11R/K3L/J2R-deleted vaccinia virusbackbone vaccinia virus