In vitro and in a rat C6-ISCG model, F3.CD-TK cells, which expressed CD and TK to convert nontoxic 5FC and GCV respectively into tumoricidal 5FU and GCV-TP near cancer cells, demonstrated a significantly higher degree of intratumor penetration, tumor topology modification, oncolytic efficacy, neurorecovery effect, and self-clearance when compared to F3.CD cells that produced CD only. The gene discussed is TKT; the disease is neoplasm.