Expression of mutant non-cleavable Fas ligand on retrovirus packaging cells causes apoptosis of immunocompetent cells and improves prodrug activation gene therapy in a malignant glioma model.

Recombinant retroviruses (RV) have been widely used as vectors for clinical gene therapy of malignant brain tumors. Because of the very limited stability of these vectors in vivo, RV producing cells (VPC) are routinely used for intratumoral RV release. The host immune system, however, recognizes the intratumorally grafted allogeneic or xenogeneic VPC, and mounts an immune response against them.