NCIt definition : A replication-deficient adenovirus type 5 (Ad5) with E1 and partial E3 deletions containing
cDNA for the herpes simplex virus thymidine kinase (HSV-Tk), which, when administered
in combination with ganciclovir (GCV), possesses potential antineoplastic activity.
Following administration, transgene-expressing cells produce thymidine kinase, which
phosphorylates GCV to ganciclovir triphosphate, a cytotoxic nucleotide analog that
is incorporated into DNA resulting in chain termination and induction of apoptosis
in rapidly dividing cells. This process spares normal neurons as they do not proliferate
and are therefore not susceptible to the toxic effects of GCV metabolites.;