Methods of administering adenoviral vectors

#The present invention relates to methods useful in the administration of gene products to animals using adenoviral vectors.

#Modified viruses have proven convenient vector systems for investigative and therapeutic gene transfer applications, and adenoviral vector systems present several advantages for such uses. Adenoviruses are generally associated with benign pathologies in humans, and the 36 kb of the adenoviral genome has been extensively studied. Adenoviral vectors can be produced in high titers (e.g., about 1013 pfu), and such vectors can transfer genetic material to nonreplicating, as well as replicating, cells (in contrast with, for example, retroviral vectors which only transfer genetic material to replicating cells). The adenoviral genome can be manipulated to carry a large amount of exogenous DNA (up to about 8 kb), and the adenoviral capsid can potentiate the transfer of even longer sequences (Curiel et al., Hum. Gene Ther., 3, 147-154 (1992)). Additionally, adenoviruses generally do not integrate into the host cell chromosome, but rather are maintained as a linear episome, thus minimizing the likelihood that a recombinant adenovirus will interfere with normal cell function. Aside from being a superior vehicle for transferring genetic material to a wide variety of cell types, adenoviral vectors represent a safe choice for gene transfer, a particular concern for therapeutic applications.

#A variety of recombinant adenoviral vectors have been described. Most of the vectors in use today derive from the adenovirus serotype 5 (Ad5), a member of subgroup C. An exogenous gene of interest typically is inserted into the early region 1 (E1) of the adenovirus. Disruption of the E1 region decreases the amount of viral proteins produced by both the early regions (DNA binding protein) and late regions (penton, hexon, and fiber proteins), preventing viral propagation. These replication deficient adenoviral vectors require growth in either a complementary cell line or in the presence of an intact helper virus, which provides, in trans, the essential E1 functions (Berker et al., J. Virol., 61, 1213-1220 (1987); Davidson et al., J. Virol., 61, 1226-1239 (1987); Mansour et al., Mol. Cell Biol., 6, 2684-2694 (1986)). More recently, adenoviral vectors deficient in both E1 and the early region 4 (E4) have been used to substantially abolish expression of viral proteins. In order to insert the larger genes (up to 8 kb) into the adenoviral genome, adenoviral vectors additionally deficient in the nonessential early region 3 (E3) are used. Multiply deficient adenoviral vectors are described in published PCT patent application WO 95/34671.

#FIG. 1 is a schematic diagram depicting the original adenovirus used to derive the adenoviral vectors AdCMVNull and AdCMV.Z, the regions of addition and deletion of the original adenovirus, and the expression cassettes of the adenoviral vectors AdCMVNull and AdCMV.Z.

#The present invention provides methods useful in the administration of gene products to animals using adenoviral gene transfer vectors. The ability to target an adenoviral vector and to repeatedly administer a therapeutic adenoviral vector in a clinical setting is useful in improving treatment efficacy and in enabling the treatment of diseases. This invention provides a method to limit the infection of non-target tissue following administration of an adenoviral vector to a particular muscle of an animal. The vector targeting potential is useful for cardiac, particularly, endocardial, administration, as the risk of misinjection of the adenoviral vector is high. As adenoviral vectors cannot be readministered systemically, the present invention also provides a method for repeat administration of an adenoviral gene transfer vector comprising an exogenous gene to the skeletal muscle of an animal.

#The term “exogenous gene”, as it is used herein, refers to any gene in an adenoviral gene transfer vector which is not native to the adenovirus which comprises the adenoviral vector. The gene includes a nucleic acid sequence encoding a gene product operably linked to a promoter. Any portion of the gene can be non-native to the adenovirus which comprises the adenoviral vector. For example, the gene can comprise a non-native nucleic acid sequence encoding a gene product which is operably linked to a native promoter. It should be appreciated that the exogenous gene can be any gene encoding an RNA or protein of interest to the skilled artisan. Therapeutic genes, genes encoding a protein that is to be studied in vitro and/or in vivo, genes encoding anti-sense RNA's, and modified viral genes are illustrative of possible exogenous genes.

#The term “adenoviral gene transfer vector”, as it is used herein, refers to any replication incompetent adenoviral vector with an exogenous gene encoding a gene product inserted into its genome. The vector must be capable of replicating and being packaged when any deficient essential genes are provided in trans. An adenoviral vector desirably contains at least a portion of each terminal repeat required to support the replication of the viral DNA, preferably at least about 90% of the full ITR sequence, and the DNA required to encapsidate the genome into a viral capsid. Many suitable adenoviral vectors have been described in the art.