CSF2 and neoplasm: The vector was generated from the HSV JS1 strain and was attenuated by functional deletion of the ICP34.5 and ICP47 viral genes, which renders the virus nonpathogenic in normal eukaryotic cells, promotes selective replication in tumor cells, and enhances immunogenicity [26] T-VEC has also been engineered to encode human GM-CSF, which further enhances the antitumor immune response.