Definition

A genetically-engineered vaccinia virus (VV) encoding a bispecific antibody specific for the tumor-associated antigen (TAA) CD19 and the T-cell surface antigen CD3, with potential oncolytic, immunostimulating and antineoplastic activities. Upon administration, the oncolytic VV expressing anti-CD19/CD3 bispecific antibody RGV004 specifically infects and replicates in tumor cells causing viral-mediated tumor cell lysis. The released virus particles, in turn, infect and replicate in neighboring tumor cells. Tumor antigens released from the lysed tumor cells also activate the immune system to induce a tumor-specific cytotoxic T-lymphocyte (CTL)-mediated immune response, thereby killing nearby non-infected tumor cells. In addition, RGV004 promotes the secretion of the anti-CD19/CD3 bispecific antibody by the infected tumor cells. The bispecific antibody targets and binds to both the CD3 on T cells and the CD19 antigen expressed on tumor cells. This results in the cross-linking of T cells and tumor cells and may induce a CTL-mediated immune response against CD19-expressing tumor cells. CD19 is a B-cell specific cell surface antigen overexpressed in B-cell lineage malignancies.