We have screened human adenoviruses (Ads) for oncolytic activity against a variety of mouse and hamster cell lines and have found a number that are susceptible to a variety of Ad serotypes. A20
lymphoma is derived from BALB/c mice and is susceptible to
infection and killing by a variety of human Ads. A20 is also a suitable
cancer vaccine model, because these cells express a unique
immunoglobulin variable region that can be targeted by vaccination. To compare Ads as
cancer vaccines versus Ads as oncolytics, A20
tumors were initiated in immunocompetent BALB/c mice. Mice immunized with first-generation Ad5 expressing the A20
immunoglobulin ScFv immunogen (Ad-A20) were protected against A20
lymphomas only when the
vaccine was delivered before
tumor. In contrast, vaccination after
tumor initiation failed to increase survival or delay
tumor growth. When Ad serotypes from species B, C, D, and E were tested as oncolytics in vitro, A20 cells were most efficiently killed by species D Ads, with intermediate activity by species B Ads. When tested in vivo in immunocompetent BALB/c mice bearing A20
tumors, single intratumoral injection of species D Ad26 and Ad48 were effective at controlling
tumor growth. These data demonstrate that in this immunocompetent mouse
cancer model, the oncolytic activity of adenoviruses is more potent than their use as a
cancer vaccine. These data in immunocompetent mice lend further support to species D Ads as promising oncolytic viruses against B cell
cancers.