Nonreplicative DNA viral vectors (i.e., adenovirus, herpes simplex virus, adeno-associated virus) have been widely used for suicide gene therapy against cancer because their strong and temporary expression of the transgene fit this purpose. Particularly, nonreplicating “adenoviral” vectors have been used in the largest number of clinical trials among all viral vectors. Thus, this chapter covers the adenovirus type 5-based nonreplicative vector.