REPLICATION-COMPETENT ANTI-CANCER VECTORS

Abstract: Novel vectors which are replication-competent in neoplastic cells and which overexpress an adenovirus death protein are disclosed. Some of the disclosed vectors are replication-restricted to neoplastic cells or to neoplastic alveolar type II cells. Compositions and methods for promoting the death of neoplastic cells using these replication-competent vectors are also disclosed.

Description: Replication-Competent Anti-Cancer Vectors Reference to Government Grant This invention was made with government support under a grant from the National Institutes of Health, Grant Number ROl CA71704 and CA81829. The United States Government has certain rights in this invention. Background of the Invention (1) Field of the Invention This invention relates generally to the treatment of cancer and more particularly to vectors which replicate in neoplastic cells and which overexpress an adenovirus death protein (ADP) and to the use of these vectors in treating human cancer. (2) Description of the Related Art Cancer is a leading cause of death in the United States and elsewhere. Depending on the type of cancer, it is typically treated with surgery, chemotherapy, and/or radiation. These treatments often fail: surgery may not remove all the cancer; some cancers are resistant to chemotherapy and radiation therapy; and chemotherapy-resistant tumors frequently develop. New therapies are necessary, to be used alone or in combination with classical techniques. One potential therapy under active investigation is treating tumors with recombinant viral vectors expressing anti-cancer therapeutic proteins. Adenovirus-based vectors contain several characteristics that make them conceptually appealing for use in treating cancer, as well as for therapy of genetic disorders. Adenoviruses (hereinafter used interchangeably with "Ads") can easily be grown in culture to high titer stocks that are stable. They have a broad host range, replicating in most human cancer cell types. Their genome can be manipulated by site-directed mutation and insertion of foreign genes expressed from foreign promoters. The adenovirion consists of a DNA-protein core within a protein capsid (reviewed by Stewart et al., "Adenovirus structure by x-ray crystallography and electron microscopy." in: The Molecular Repertoire of Adenoviruses, Doerfler, W. et al., (ed)., Springer- Verlag, Heidelberg, Germany, p. 25-38). Virions bind to a specific cellular receptor, are endocytosed, and the genome is extruded from endosomes and transported to the nucleus. The genome is a linear duplex DNA of about 36 kbp, encoding about 36 genes (Fig. IA). In the nucleus, the "immediate early" El A proteins are expressed initially, and these proteins induce expression of the "delayed early" proteins encoded by the E1B, E2, E3, and E4 transcription units (reviewed by Shenk, T. "Adenoviridae: the viruses and their replication" in: Fields Virology, Field, B.N. et al., Lippencott-Raven, Philadelphia, p. 2111-2148). E1A proteins also induce or repress cellular genes, resulting in stimulation of the cell cycle. About 23 early proteins function to usurp the cell and initiate viral DNA replication. Viral DNA replicates at about 7 h post-infection (p.i.), then late genes are expressed from the "major late" transcription unit. Major late mRNAs are synthesized from the common "major late promoter" by alternative pre-mRNA processing. Each late mRNA contains a common "tripartite leader" at its 5'- terminus (exons 1, 2, and 3 in Fig. 1), which allows for efficient translation of Ad late mRNAs. Cellular protein synthesis is shut off, and the cell becomes a factory for making viral proteins. Virions assemble in the nucleus at about 1 day p.i., and after 2-3 days the cell lyses and releases progeny virus. Cell lysis is mediated by the E3 11.6K protein, which has been renamed "adenovirus death protein" (ADP) (Tollefson et al., J. Virol. 70:2296-2306, 1996; Tollefson et al., Virol. 220:152-162, 1996). The term ADP as used herein in a generic sense refers collectively to ADP's from adenoviruses such as, e.g. Ad type 1 (Adl), Ad type 2 (Ad2), Ad type 5 (Ad5) or Ad type 6 (Ad6) all of which express homologous ADP's with a high degree of sequence similarity. Human adenovirus type 5 (Ad5) is particularly useful for cancer gene therapy. It primarily causes asymptomatic or mild respiratory infections in young children, followed by long term effective immunity. Fatalities are extremely rare except when the patient is immunocompromised (Horwitz, M. S., Adenoviruses, p. 2149-2171 In B. N. Fields, D. M. Knipe, and P. M. Howley (eds.), Fields Virology, Lippincott-Raven Publishers, Philadelphia, PA, 1996). Ad5 is very well understood, can be grown in culture to high titer stocks that are stable, and can replicate in most human cancer cell types (Shenk, T., Adenoviridae: the viruses and their replication, p. 2111-2148. In B. N. Fields, D. M. Knipe, and P. M. Howley (eds.), Fields Virology, Lippincott-Raven, Philadelphia, 1996). Its genome can be manipulated by site-directed mutagenesis and insertion of foreign sequences. The Ad vectors being investigated for use in anti-cancer and gene therapy are based on recombinant Ad's that are either replication-defective or replication-competent. Typical replication-defective Ad vectors lack the EIA and EIB genes (collectively known as El) and contain in their place an expression cassette consisting of a promoter andpre-mRNA processing signals which drive expression of a foreign gene. The EIA proteins induce transcription of other Ad genes, and in nontransformed cells they deregulate the cell cycle, induce or repress a variety of cellular genes, and force cells from G 0 into S-phase 48 (White, E., Semin. Virol. 5:505-513, 1998; Wold et al., pp. 200-232 In A.J. Cann (ed.), DNA Virus Replication: Frontiers in Molecular Biology, Oxford University Press, Oxford). The EIB proteins inhibit cellular apoptosis. Id. These vectors are unable to replicate because they lack the El A genes required to induce Ad gene expression and DNA replication. In addition, the E3 genes are usually deleted because they are not essential for virus replication in cultured cells. A number of investigators have constructed replication-defective Ad vectors expressing anti-cancer therapeutic proteins. Usually, these vectors have been tested by direct injection of human tumors growing in mouse models. Most commonly, these vectors express the thymidine kinase gene from herpes simplex virus, and the mice are treated with gancyclovir to kill cells transduced by the vector (see e.g., Felzmann et al., Gene Ther. 4: 1322-1329, 1997). Another suicide gene therapy approach involves injecting tumors with a replication defective Ad vector expressing cytosine deaminase, followed by administration of 5-fluorocytosine (Topf et al., Gene Ther. 5:507-513, 1998). Investigators have also prepared and tested replication-defective Ad vectors expressing a cytokine-such as IL-2, IL-12, IL-6, tumor necrosis factor (TNF), type I interferons, or the co-stimulatory molecule B7-1 in the anticipation that the Ad-expressed cytokine will stimulate an immune response, including cytotoxic T-lymphocytes (CTL), against the tumor (Felzmann et al., supra; Putzer et al., Proc. Natl. Acad. Sci. USA 94:10889-10894, 1997). Other vectors express tumor antigens (e.g. melanoma MARTI), proteins that de-regulate the cell cycle and induce apoptosis (p53, pRB, P 21 Kipl/WAF1 , pl6 CDKN2 , and even Ad EIA), and ribozymes. An Ad vector expressing FasL induces apoptosis and tumor regression of a mouse tumor (Arai et al., Proc. Natl. Acad. Sci. USA 94:13862-13867, 1997). Despite these generally positive reports, it is recognized in the art that replication-defective Ad vectors have several characteristics that make them suboptimal for use in therapy. For example, production of replication-defective vectors requires that they be grown on a complementing cell line that provides the EIA proteins in trans. Such cell lines are fastidious, and generation of virus stocks is time-consuming and expensive. In addition, although many foreign proteins have been expressed from such vectors, the level of expression is low compared to Ad late proteins. To address these problems, several groups have proposed using replication- competent Ad vectors for therapeutic use. Replication-competent vectors retain Ad genes essential for replication and thus do not require complementing cell lines to replicate. Replication-competent Ad vectors lyse cells as a natural part of the life cycle of the vector. Another advantage of replication-competent Ad vectors occurs when the vector is engineered to encode and express a foreign protein. Such vectors would be expected to greatly amplify synthesis of the encoded protein in vivo as the vector replicates. However, in order to prevent RC vectors from damaging normal tissues and causing disseminated viremia, it is important that they have some feature that limits their replication to cancer cells. Wyeth Laboratories developed replication-competent Ad vectors for vaccination purposes, using vaccine strains of Ad serotypes 4, 7, and 5 (Lubeck et al., AIDS Res. Hum. Retroviruses 10: 1443-1449, 1994). Foreign genes were inserted into the E3 region (with the E3 genes deleted) or into a site at the right end of the genome. Two foreign genes used were hepatitis B surface antigen and the HIV envelope protein. They obtained good expression in culture, and were able to raise antisera in animal models. Phase I human trials were ambiguous, and the project was mostly abandoned. Onyx Pharmaceuticals recently reported on adenovirus-based anti-cancer vectors which are replication deficient in non-neoplastic cells but which exhibit a replication phenotype in neoplastic cells lacking functional p53 and or retinoblastoma (pRB) tumor suppressor proteins (U.S. Patent No. 5,677,178; Heise et al., Nature Med. 6:639-645, 1997; Bischoff et al., Science 274:373-376, 1996). This phenotype is reportedly accomplished by using recombinant adenoviruses containing a mutation in the EIB region that make the encoded E1B-55K protein incapable of binding to p53 and or a mutation(s) in the EIA region which make the encoded EIA protein (p289R or p243R) incapable of binding to pRB and/or the cellular 300 kD polypeptide and or the 107 kD polypeptide. E1B-55K has at least two independent functions: it binds and inactivates the tumor suppressor protein p53, and it is required for efficient transport of Ad mRNA from the nucleus. Because these EIB and EIA viral proteins are involved in forcing cells into S-phase, which is required for replication of adenovirus DNA, and because the p53 and pRB proteins block cell cycle progression, the recombinant adenovirus vectors described by Onyx should replicate in cells defective in p53 and/or pRB, which is the case for many cancer cells, but not in cells with wild-type p53 and/or pRB. Onyx has reported that replication of an adenovirus lacking E1B-55K, which is named ONYX-015, was restricted to p53-minus cancer cell lines (Bischoff et al., supra), and that ONYX-015 slowed the growth or caused regression of a p53 -minus human tumor growing in nude mice (Heise et al., supra). Others have challenged the Onyx report claiming that replication of ONYX-015 is independent of p53 genotype and occurs efficiently in some primary cultured human cells (Harada and Berk, J. Virol 75:5333-5344, 1999). It is now known that ONYX-015 can replicate in cells with wild-type p53 (Goodrum et al., J. Virol. 72:9479-9490, 1998; Harada et al., J. Virol. 75:5333-5344, 1999; Hay et al., Hum. Gene Ther. 70:579-590, 1999; Rothmann et al., J. Virol. 72:9470-9478, 1998; Turnell et al., J. Virol. 75:2074-2083, 1999). ONYX-015 does not replicate as well as wild-type adenovirus because E1B-55K is not available to facilitate viral mRNA transport from the nucleus. Also, ONYX- 015 expresses less ADP than wild-type virus (see Example 1 below). As an extension of the ONYX-015 concept, a replication-competent adenovirus vector was designed that has the gene for E1B-55K replaced with the herpes simplex virus thymidine kinase gene (Wilder et al., Gene Therapy 6:57-62, 1999). The group that constructed this vector reported that the combination of the vector plus gancyclovir showed a therapeutic effect on a human colon cancer in a nude mouse model (Wilder et al., Cancer Res. 59:410-413, 1999). However, this vector lacks the gene for ADP, and accordingly, the vector will lyse cells and spread from cell-to-cell less efficiently than an equivalent vector that expresses ADP. The gene for ADP is also lacking in another replication-competent adenovirus vector that has been described, in which a minimal enhancer/promoter of the human prostate specific antigen was inserted into the adenovirus EIA enhancer/promoter (Rodriguez et al., Cancer Res. 57:2559-2563, 1997). Another strategy for replication-competent vector improvement is to place replication under the control of tissue-specific promoters. One group replaced the basal EIA promoter with a modified promoter for α-fetoprotein (AFP) (Hallenbeck et al., Hum. Gene Ther. 70:1721-1733, 1999). AFP is expressed in the liver during development, but it is not expressed in adults. However, it is expressed in 70-80% of patients with hepatocellular carcinoma. Growth of this vector was limited to AFP-expressing cells and the vector showed some suppression of xenotransplants. Id. A series of RC vectors has also been developed that have expression of the EIA and EIB genes dependent on the prostate tumor-specific prostate specific antigen (PSA) and kallikrein promoters/enhancers (Rodriguez et al., Cancer Res. 60:1196, 1997; Yu et al., Cancer Res.59:4200-4203, 2000; Yu et al., Cancer Res 59:1498-1504, 1999). Thus, there is a continuing need for vectors that replicate and spread efficiently in tumors but that can be modified such that they replicate poorly or not at all in normal tissue. Summary of the Invention Briefly, therefore, the present invention is directed to novel vectors which are replication competent in neoplastic cells and which overexpress an adenovirus death protein (ADP). The work reported herein demonstrates the discovery that overexpression of ADP by a recombinant adenovirus allows the construction of a replication-competent adenovirus that kills neoplastic cells and spreads from cell-to-cell at a rate similar to or faster than that exhibited by adenoviruses expressing wild-type levels of ADP, even when the recombinant adenovirus contains a mutation that would otherwise reduce its replication rate in non- neoplastic cells. This discovery was unexpected because it could not have been predicted from what was known about adenovirus biology that Ad vectors overexpressing ADP remain viable and that the infected cells are not killed by the higher amounts of ADP before the Ad vector produces new virus particles that can spread to other tumor cells. Indeed, naturally- occurring adenoviruses express ADP in low amounts from the E3 promoter at early stages of infection, and begin to make ADP in large amounts only at 24-30 h p.i., once virions have been assembled in the cell nucleus. It is believed that other non-adenoviral vectors can be used to deliver ADP's cell-killing activity to neoplastic cells, including other viral vectors and plasmid expression vectors. Thus, in one preferred embodiment, the ADP-expressing vector comprises a recombinant adenovirus lacking expression of at least one E3 protein selected from the group consisting of: gpl9K; RIDα (also known as 10.4K); RIDβ (also known as 14.5K) and 14.7K. Because these E3 proteins inhibit immune-mediated inflammation and/or apoptosis of Ad- infected cells, it is believed that a recombinant adenovirus lacking one or more of these E3 proteins will stimulate infiltration of inflammatory and immune cells into a tumor treated with the adenovirus and that this host immune response will aid in destruction of the tumor as well as tumors that have metastasized. The ADP expressed by preferred embodiments comprises a naturally-occurring amino acid sequence from a human adenovirus of subgroup C, namely Adl, Ad2, Ad5 and Ad6. In another embodiment, replication of the vector is restricted to neoplastic cells. Such replication-restricted vectors are useful in treating cancer patients in which it is desirable to eliminate or reduce damage to normal cells and tissues that might be caused by the vector, particularly viral vectors that kill the host cell as part of their life cycle. In preferred embodiments, a recombinant adenovirus has a replication-restricted phenotype because the recombinant adenovirus is incapable of expressing an EIA viral protein which binds the pRB and the p300/CBP proteins or because the E4 promoter has been substituted with a promoter that is activated only in neoplastic cells and or cells of a specific tissue. In yet another embodiment, the invention provides a vector which overexpresses ADP and whose replication is under the control of a tissue specific promoter, tumor specific promoter or an inducible promoter. In preferred embodiments, the vector compnses a recombinant adenovirus m which the tissue specific promoter or inducible promoter is substituted for the E4 promoter. Such vectors are useful for restricting replication of the vector and its ADP-mediated cell killing to cells of a particular type or to cells exposed to an exogenous agent that activates the promoter. A preferred tissue-specific or inducible vector also expresses a phenotype that restricts its replication to neoplastic cells. In yet another embodiment, the invention provides a vector which overexpresses ADP but which is not restπcted to tumors by a specific genetic modification. Such a vector is more destructive to neoplastic cells than even the naturally occurring Ad's of subgroup C. In preferred embodiments, this vector could be used for patients with terminal cancer not treatable by another method, and who have pre-existing neutralizing antibodies to Ad or to which neutralizing antibodies can be administered. In still another embodiment, the invention provides a composition compnsmg a first recombinant virus which is replication competent in a neoplastic cell and overexpresses the adenovirus death protein. In one embodiment, the recombmant virus is contained withm a delivery vehicle compnsmg a targeting moiety that limits delivery of the virus to cells of a certain type. With this embodiment, the replication-competent vector can be of any ADP- overexpressmg configuration descnbed herein. In some embodiments, the composition also compnses a second recombmant virus which is replication-defective and which expresses an anti-cancer gene product. In some embodiments, the replication-defective vector may be engineered to overexpress ADP when replication of this vector is complemented by a replication-competent vector. The recombinant virus complements spread of the replication- defective virus, as well as its encoded anti-cancer product, throughout a tumor. In preferred embodiments, the first recombmant virus is a recombinant adenovirus whose replication is restπcted to neoplastic cells and/or which lacks expression of one or more of the E3 gpl9K; RTDα; RIDβ; and 14.7K protems In additional embodiments, the invention provides replication-competent vectors that overexpresses an ADP and also expresses an anti-cancer product. As with previous embodiments, the vector can be of any ADP-overexpressmg configuration provided herein. Preferably, replication of the virus is engineered to (a) be restncted to neoplastic cells, e.g., by replacing the E4 promoter with a tissue specific or tumor specific promoter and/or (b) lack expression of one or more of the E3 gpl9K; RIDα; RTDβ; and 14.7K proteins. In some embodiments, the anti-cancer product is inserted mto the E3 region. The ADP-expressmg vectors and compositions of the invention are useful in a method for promoting death of a neoplastic cell. The method compnses contacting the neoplastic cell with a vector which is replication-competent m the neoplastic cell and which overexpresses ADP. Where the neoplastic cell comprises a tumor in a patient, the vector is administered directly to the tumor or, in other embodiments, the vector is administered to the patient systemically or in a delivery vehicle containing a targeting moiety that directs delivery of the vector to the tumor. In embodiments where the vector is a recombinant virus, the method can also comprise passively immunizing the patient against the virus. In yet another embodiment of the invention, the vector may be used in combination with radiation therapy. The radiation therapy can be any form of radiation therapy used in the art such as for example, external beam radiation such as x-ray treatment, radiation delivered by insertion of radioactive materials within the body near or at the tumor site such as treatment with gamma ray emitting radionuclides, particle beam therapy which utilizes neutrons or charged particles and the like. In addition, this embodiment encompasses the use of more than one of the vectors of the present invention in a cocktail in combination with radiation therapy. Another embodiment of the invention involves the use of the recombinant vector in combination with chemotherapy as has been disclosed for other adenovirus vectors (U.S. Patent No. 5,846,945). Chemotheraputic agents are known in the art and include antimetabolites including pyrimidine-analogue and purine-analogue antimetabolites, plant alkaloids, antitumor antibiotics, alkylating agents and the like. The use of more than one of the vectors of the present invention with a chemotheraputic agent or agents is also contemplated within this embodiment. Among the several advantages found to be achieved by the present invention, therefore, may be noted the provision of replication-competent vectors, particularly viruses, which rapidly kill cancer cells and spread from cell-to-cell in a tumor; the provision of such vectors whose replication can be induced or which is restricted to tumors and or to cells of a certain tissue type; and the provision of compositions and methods for anti-cancer therapy which cause little to no side effects in normal tissues. Brief Description of the Drawings Figure 1 is a schematic of gene expression in Ad5 (Fig. IA) and KD3, a preferred embodiment of the invention (Fig. IB), in which the respective genomes are represented by the stippled bars and transcription units represented by arrows above and below the bars, with the E3 proteins listed above the arrows for the E3 transcription unit, and the LI to L5 families of late mRNA's indicated. Figure 2 illustrates the overexpression of ADP by KD1, KD3 , GZ1, and GZ3 showing an immunoblot of proteins isolated from human A549 cells infected with the indicated viruses and probed with an anti- ADP antibody, with ADP indicating differently glycosylated andproteolytically processed forms of ADP. Figure 3 illustrates that the EIA dll 101/1107 mutation referred to in the figure and hereinafter as dl0l/07, retards expression of late proteins, showing an immunoblot of EIA proteins and late proteins in A549 cells infected with the indicated viruses in the absence (Figs. 3A and 3B) or presence (Figs. 3C and 3D) of dl327, which has a wild-type EIA region and has a deletion of all E3 genes but the gene encoding the 12.5K protein (Figs. 3C and 3D). An antiserum specific to the EIA proteins was used for Fig. 3A and 3C. An antiserum raised against Ad5 virions was used for Figs. 3B and 3D. Figure 4 illustrates that KD1 and KD3 kill cells more efficiently than control viruses that express less or no ADP, showing a graph of the percent of A549 cells infected with the indicated viruses that were viable at the indicated days p.i. as determined by trypan blue exclusion. Figure 5 is a cell spread assay illustrating that overexpression of ADP enhances spread of virus from cell to cell, showing monolayers infected with the indicated viruses at the indicated PFU/cell which were treated at 7 days p.i. with crystal violet, which stains live cells but not dead cells. Figure 6 illustrates that KD1 and KD3 replicate well in growing cells but not in growth-arrested cells showing the virus titer extracted from growing or growth arrested HEL- 229 cells at various times following infection with 100 PFU/ml of the following viruses: dl309 (Fig. 6A), .#01/07 (fig. 6B), KD1 (Fig. 6C) and KD3 (Fig 6D). Figure 7 illustrates that KD1 and KD3 are defective in killing primary human bronchial epithelial cells showing these cell monolayers infected at 30% confluency with 10 PFU/ml of the indicated viruses and stained at 5 days p.i. with neutral red. Figure 8 illustrates that KD1 and KD3 reduce the growth rate of human A549 cell tumors growing in nude mice, showing in Fig. 8 A a graph of average-fold increase in tumor size plotted against the number of weeks following infection of the tumor with buffer or with 5 x 10 7 PFU at weekly intervals of or the indicated viruses, and showing in Fig. 8B a similar graph of tumors injected once with 5 x 10 8 PFU of KD3 or GZ3. Figure 9 illustrates that KD1 and KD3 reduce the growth rate of human Hep3B cell tumors growing in nude mice, showing a graph of average-fold increase in tumor size plotted against the number of weeks following injection of the tumor with buffer or with 5 x 10 7 PFU of dl309, KD1 or KD3 at twice weekly intervals of the indicated viruses. Figure 10 illustrates that KD1 and KD3 complement the replication and spread of Ad- β-gal, a replication-defective vector that expresses β-galactosidase, using an infectious center assay showing in Fig. 10A a picture of A549 cell monolayers seeded with A549 cells infected with Ad-β-gal alone or with the indicated viruses, with Figs 10B and 10C showing close-up views of two of the monolayers of Fig. 10A. Figure 11 is a bar graph illustrating that KD1 and KD3 increase the expression of luciferase in human Hep3B cell tumors growing in nude mice, using an assay in which tumors were injected with the indicated combinations of viruses, then were extracted 2 weeks p.i. and assayed for luciferase activity. The numbers in parentheses indicated the fold increase in luciferase activity compared to that of the Adluc vector plus buffer. Figure 12 is a graph showing the results of a standard plaque development assay for KD1 and KD1-SPB on A549 cells engineered to express the TTF1 transcription factor (A549/TTF1) and the parental 549 cells, in which data are plotted as the number of plaques observed on a particular day in the assay divided by the final number of plaques observed for that virus multiplied by 100. Figure 13 is a cell spread assay for KD1 and KD1-SPB on H441 cells and Hep3B cells, where cells were infected with the indicated amounts of KD1 or KD1-SPB and H441 cells and Hep3B cells were strained with crystal violet at 5 days p.i. and 8 days p.i., respectively. Figure 14 is a graph showing the results of a standard plaque development assay for dl309 and two preferred embodiments of the invention, GZl and GZ3, in which data are plotted as the number of plaques observed on a particular day in the assay divided by the final number of plaques observed for that virus multiplied by 100. Figure 15 is a cell spread assay illustrating that the combination of KD1, KD3, GZl, or GZ3 with x-ray radiation is more effective in destroying A549 cell monolayers than is virus vector alone or radiation alone, wherein cells were infected with the indicated amounts of the indicated viruses, radiated with 600 centigreys (cGy) of x-radiation (bottom panel), or mock radiated (top panel), then stained with crystal violet at 6 days p.i. Figure 16 is a graph of a cell spread assay illustrating that 10 "3 PFU of KD1, KD3, GZl, or GZ3 used in combination with 150, 300, or 600 centigreys of radiation is more effective in destroying A549 cell monolayers than virus vector alone or radiation alone. Cell viability is based on the amount of crystal violet extracted from the culture wells, using the mock-infected non-radiated well as 100% viability. Figure 17 illustrates that the combination of KD3 or GZ3 plus x-ray radiation is more effective in reducing the growth of A549 cell tumors growing in nude mice than KD3 alone or GZ3 alone. Figure 18 illustrates a structure-function analysis of ADP, showing in Fig. 18A the amino acid sequence of the adenovirus death protein encoded by Ad2, with the various putative domains and glycosylation sites labeled and showing in Fig. 18B a schematic of the ADP gene in rec700 and in the indicated deletion mutants, with the right column summarizing the death promoting phenotype of the various mutants as a percentage of the wild-type phenotype. Figures 19A and 19B illustrate a cell viability assay of the indicated ADP mutants showing a graph of viability as determined by trypan blue exclusion plotted against hours (Fig. 19A) or days (Fig. 19B) postinfection. Figure 20 depicts the amino acid sequence, shown in single letter code, for the ADP proteins of Adl, Ad2, Ad5, and Ad6 (SEQ ID NOS:5-8), for the Ad2 ADP mutants dl7\6, c#715, dl7\4, and dl737 (SEQ ID NOS:9-12), and for the putative lumenal domain (SEQ ED NO: 17), the transmembrane domain (SEQ ID NO: 18), the cytosolic basic-proline domain (SEQ ED NO:19), and the remainder of the cystosolic domain (SEQ ED NO:20) of the ADP protein of Ad2. Figure 21 presents the complete nucleotide sequence of the genome of Ad5. Figure 22 presents the complete nucleotide sequence of the genome of KD1 (SEQ ED NO:l). Figure 23 presents the complete nucleotide sequence of the genome of KD3 (SEQ ED NO:2). Figure 24 is a schematic of the following vectors: A. Ad5. The stippled bar indicates the DNA genome of 36 kbp. The open arrow indicates the immediate early EIA transcription unit, and the black arrows are the delayed early EIB, E2, E3, and E4 transcription units. The hatched arrows indicate the five families of major late mRNAs, and also the ADP mRNA, which is synthesized as part of the major late transcription unit. Each major late mRNA has a tripartite leader (leaders 1, 2, and 3) spliced to its 5' terminus. B. d!309. dl309 is identical to Ad5 except it has the E3-RED and E3-14.7K genes deleted. dl309 expresses ADP at levels similar to Ad5. C. KD1. KD1 has two small deletions (indicated by "X" marks) in the EIA gene that abolish binding of the EIA proteins to pRB or p300/CBP. It lacks all E3 genes except adp. ADP is expressed earlier in infection and in greater abundance than is ADP from Ad5 or dl309 Doronin et al., J. Virol. 74:6147-6155. D. KD1-SPB. KD1- SPB is identical to KD1, except it has the E4 promoter replaced by the promoter for Surfactant Protein B (SPB-P). Figure 25 presents graphs illustrating that KD1-SPB grows as well as KD1 in H441 lung carcinoma cells but much more poorly than KD1 in Hep 3B hepatoma cells. CsCl- banded stocks of KD1-SPB and KD1 were titered using standard methods (Tollefson et al., p. 1-9 In W.S.M. Wold (ed.), Adenovirus Methods and Protocols. Humana Press, Inc., Totowa, NJ, 1998) on 293-E4 or 293 cells (A), or on A549 cells (B). The data are plotted as the number of plaques seen on any day of the plaque assay as a percentage of the number of plaques seen on the final day of the assay (Tollefson et al., Virology 220:152-162, 1996). Figure 26 presents micrographs illustrating that KDl-SPB induces CPE in H441 cells but not Hep 3B cells. H441 and Hep 3B monolayers were mock-infected or infected with 10 PFU/cell of KDl or KDl-SPB, then photographed under phase contrast at 4 or 7 days p.i. Figure 27 depicts Southern hybridizations and a graph illustrating that KDl-SPB DNA is synthesized efficiently in H441 but not Hep 3B cells. H441 or Hep 3B cells were infected with 10 PFU/cell of KDl or KDl-SPB. Total genomic DNA was isolated at 0, 5, 24, 48, 72, and 96 h p.i., digested with Hindlll, resolved by agarose gel electrophoresis, blotted, and hybridized with 32 P-labeled Ad DNA. A. Autoradiogram. B. Phosphor mager quantitation of the DNA bands in Panel A. Figure 28 presents graphs depicting single step growth curves showing that KDl-SPB grows well in H441 but not Hep 3B cells. Cells were infected with 10 PFU/cell of KDl or KDl-SPB. Vectors were extracted at the indicated days p.i. and titers determined by plaque assay. Figure 29 depicts immunoblots showing that KDl-SPB expresses E40RF3 and ADP in H441 but not Hep 3B cells. Cells were infected with 10 PFU/cell of KDl or KDl-SPB. At 24 h p.i., protein extracts were analyzed for EIA, E40RF3, and ADP using specific antisera. The EIA proteins appear as multiple bands. ADP appears as two bands; the upper band is glycosylated and the lower band is a proteolytically cleaved species (Scaria et al., Virology 191:743-753, 1992; Tollefson et al., J. Virol. 66:3633-3642). Figure 30 depicts immunofluorescence micrographs showing that KDl-SPB expresses E40RF3 in H441 but not Hep 3B cells. Cells growing on coverslips were infected with 20 PFU/cell of KDl, KDl-SPB, or dl309 (wild-type). At 48 h (Panel A) or 6 days (Panel B), cells were fixed and stained with a rabbit polyclonal antipeptide antiserum against E40RF3. Photographs were taken using a 100X Planapo lens. Each panel shows about 8 nuclei. This figure is part of the same experiment shown in Figure 31. Figure 31 depicts immunofluorescence micrographs showing that KDl-SPB does not express E2-DBP or fiber efficiently in Hep 3B cells. Hep 3B cells were infected with 20 PFU/cell of KDl-SPB or KDl. At 48 h (A) or 6 days (B) p.i., cells were fixed and double- stained using a rabbit polyclonal antiserum against DBP and a mouse monoclonal antibody against fiber. The same fields are shown for DBP and fiber. This figure is part of the same experiment shown in Figure 30. Figure 32 presents graphs illustrating that KDl-SPB lyses H441 but not Hep 3B as efficiently as KDl. H441 or Hep 3B cells were mock-infected or infected with 20 PFU/cell of KDl or KDl-SPB. Cell lysis was determined by release of lactate dehydrogenase from the cells into the medium. Figure 33 presents graphs illustrating that KDl-SPB suppresses growth of H441 tumors in nude mice equally as well as KDl. Tumor cells were injected into flanks of nude mice and allowed to grow to about 100 μl (H441) or 150 μl (Hep 3B) volumes. Tumors (n = 10) were injected with DMEM (mock) or with 5 x 10 7 PFU of KDl or KDl-SPB. Injections of the viruses were repeated twice weekly for 3 weeks to a total dose of 3.0 x 10 8 PFU per tumor. Tumors were measured and the mean fold-increase in tumor size was calculated. Description of the Preferred Embodiments In accordance with the present invention, it has been discovered that overexpression of ADP by a recombinant adenovirus results in faster lysis of cells and spread of the virus throughout a cell monolayer than viruses expressing wild-type levels of ADP. It has also been discovered that this function for ADP is manifest in an adenovirus that contains EIA mutations that restrict adenoviral replication to neoplastic cells. Thus, vectors which are both replication competent in neoplastic cells and which overexpress ADP should be useful in anti- cancer therapy. In the context of this disclosure, the following terms will be defined as follows unless otherwise indicated: "Naturally-occurring" as applied to an object such as a polynucleotide, polypeptide, or virus means that the object can be isolated from a source in nature and has not been intentionally modified by a human. "Neoplastic cell" means a cell which exhibits an aberrant growth phenotype characterized by a significant loss of control of cell proliferation and includes actively replicating cells as well as cells in a temporary non-replicative resting state (Gi or G 2 ). A neoplastic cell may have a well-differentiated phenotype or a poorly-differentiated phenotype and may comprise a benign neoplasm or a malignant neoplasm. "Recombinant virus" means any viral genome or virion that is different than a wild- type virus due to a deletion, insertion, or substitution of one or more nucleotides in the wild- type viral genome. The recombinant virus can have changes in the number of amino acid sequences encoded and expressed or in the amount or activity of proteins expressed by the virus. In particular, the term includes recombinant viruses generated by the intervention of a human. "Replication-competent" as applied to a vector means that the vector is capable of replicating in normal and/or neoplastic cells. As applied to a recombinant virus, "replication- competent" means that the virus exhibits the following phenotypic characteristics in normal and/or neoplastic cells: cell infection; replication of the viral genome; and production and release of new virus particles; although one or more of these characteristics need not occur at the same rate as they occur in the same cell type infected by a wild-type virus, and may occur at a faster or slower rate. Where the recombinant virus is derived from a virus such as adenovirus that lyses the cell as part of its life cycle, it is preferred that at least 5 to 25% of the cells in a cell culture monolayer are dead 5 days after infection. Preferably, a replication- competent virus infects and lyses at least 25 to 50%, more preferably at least 75%, and most preferably at least 90% of the cells of the monolayer by 5 days post infection (p.i.). "Replication-defective" as applied to a recombinant virus means the virus is incapable of, or is greatly compromised in, replicating its genome in any cell type in the absence of a complementing replication-competent virus. Exceptions to this are cell lines such as 293 cells that have been engineered to express adenovirus EIA and EIB proteins. "Replication-restricted" as applied to a vector of the invention means the vector replicates better in a dividing cell, i.e. either a neoplastic cell or a non-neoplastic, dividing cell, than in a cell of the same type that is not neoplastic and/or not dividing, which is also referenced herein as a normal, non-dividing cell. Preferably, a replication-restricted virus kills at least 10% more neoplastic cells than normal, non-dividing cells in cell culture monolayers of the same size, as measured by the number of cells showing cytopathic effects (CPE) at 5 days p.i. More preferably, between 25% and 50%, and even more preferably, between 50% and 75% more neoplastic than normal cells are killed by a replication-restricted virus. Most preferably, a replication-restricted adenovirus kills between 75% and 100% more neoplastic than normal cells in equal sized monolayers by 5 days p.i. In one embodiment the invention provides a vector that is replication-competent in neoplastic cells and which overexpresses an ADP. Vectors useful in the invention include but are not limited to plasmid-expression vectors, bacterial vectors such as Salmonella species that are able to invade and survive in a number of different cell types, vectors derived from DNA viruses such as human and non-human adenoviruses, adenovirus associated viruses (AAVs), poxviruses, herpesviruses, and vectors derived from RNA viruses such as retroviruses and alphaviruses. Preferred vectors include recombinant viruses engineered to overexpress an ADP. Recombinant adenoviruses are particularly preferred for use as the vector, especially vectors derived from Adl, Ad2, Ad5 or Ad6. Vectors according to the invention overexpress ADP. As applied to recombinant Ad and AAV vectors, the term "overexpresses ADP" means that more ADP molecules are made per viral genome present in a dividing cell infected by the vector than expressed by any previously known recombinant adenoviral vector or AAV in a dividing cell of the same type. As applied to other, non-adenoviral vectors, "overexpresses ADP" means that the virus expresses sufficient ADP to lyse a cell containing the vector. Vectors overexpressing ADP can be prepared using routine methodology. See, e.g., A Laboratory Cloning Manual, 2nd Ed., vol. 3, Sambrook et al., eds., Cold Spring Harbor Laboratory Press, 1989. For example, a polynucleotide encoding the ADP can be cloned into a plasmid expression vector known to efficiently express heterologous proteins in mammalian cells. The polynucleotide should also include appropriate termination and polyadenylation signals. Enhancer elements may also be added to the plasmid to increase the amount of ADP expression. Viral vectors overexpressing ADP can be prepared using similar materials and techniques. Where the virus is a recombinant adenovirus, overexpression of ADP can be achieved in a multitude of ways. In general, any type of deletion in the E3 region that removes a splice site for any of the E3 mRNAs will lead to overexpression of the mRNA for ADP, inasmuch as more of the E3 pre-mRNA molecules will be processed into the mRNA for ADP. This is exemplified in the KDl, KD3, GZl and GZ3 vectors (SEQ ED NOS:l-4) whose construction is described below. Other means of achieving overexpression of ADP in Ad vectors include, but are not limited to: insertion of pre-mRNA splicing and cleavage/polyadenylation signals at sites flanking the gene for ADP; expression of ADP from another promoter, e.g. the human cytomegalovirus promoter, inserted into a variety of sites in the Ad genome; and insertion of the gene for ADP behind the gene for another Ad mRNA, together with a sequence on the 5' side of the ADP sequence that allows for internal initiation of translation of ADP, e.g. the Ad tripartite leader or a viral internal ribosome initiation sequence. The ADP expressed by a vector according to the invention is any polypeptide comprising a naturally-occurring full-length ADP amino acid sequence or variant thereof that confers upon a vector expressing the ADP the ability to lyse a cell containing the vector such that replicated copies of the vector are released from the infected cell. A preferred full-length ADP comprises the ADP amino acid sequence encoded by Adl, Ad2, Ad5 or Ad6. These naturally-occurring ADP sequences are set forth in SEQ ED NOS:5-8, respectively. ADP variants include fragments and deletion mutants of naturally-occurring adenovirus death proteins, as well as full-length molecules, fragments and deletion mutants containing conservative amino acid substitutions, provided that such variants retain the ability, when expressed by a vector inside a cell, to lyse the cell. Conservative amino acid substitutions refer to the interchangeability of residues having similar side chains. Conservatively substituted amino acids can be grouped according to the chemical properties of their side chains. For example, one grouping of amino acids includes those amino acids having neutral and hydrophobic side chains (A, V, L, I, P, W, F, and M); another grouping is those amino acids having neutral and polar side chains (G, S, T, Y, C, N, and Q); another grouping is those amino acids having basic side chains (K, R, and H); another grouping is those amino acids having acidic side chains (D and E); another grouping is those amino acids having aliphatic side chains (G, A, V, L, and I); another grouping is those amino acids having aliphatic-hydroxyl side chains (S and T); another grouping is those amino acids having amine-containing side chains (N, Q, K, R, and H); another grouping is those amino acids having aromatic side chains (F, Y, and W); and another grouping is those amino acids having sulfur-containing side chains (C and M). Preferred conservative amino acid substitutions groups are: R-K; E-D, Y-F, L-M; V-I, and Q-H. As used herein, an ADP variant can also include modifications of a naturally- occurring ADP in which one or more amino acids have been inserted, deleted or replaced with a different amino acid or a modified or unusual amino acid, as well as modifications such as glycosylation or phosphorylation of one or more amino acids so long as the ADP variant containing the modified sequence retains cell lysing activity. As described below, the inventors herein performed a structure-function analysis of ADP that defined specific domains in ADP required to promote cell death. Using this information, when combined with known recombinant DNA and cloning methodology, it is believed the skilled artisan can readily construct ADP variants of a naturally-occurring adenovirus death protein and test them for cell lysing activity. A preferred ADP deletion mutant comprises an ADP amino acid sequence from any of the deletion mutants dl7\6, dπ 15, dϊl\4 and -#737, whose ADP sequences are set forth in SEQ ED NOS:9-12, respectively). Where the vector is derived from a virus, it is preferred that the virus lack expression of one or more viral proteins involved in avoiding host anti-viral defenses such as immune- mediated inflammation and/or apoptosis of infected cells. For example, adenovirus contains a cassette of genes that prevents killing of Ad-infected cells by the immune system (Wold et al., Semin. Virol, 1998 (8:515-523, 1998). The E3-14.7K protein and the E3 RED (Receptor Internalization and Degradation) protein, which is a complex consisting of REDα and REDβ, inhibit apoptosis of Ad-infected cells induced by tumor necrosis factor (TNF) and the Fas ligand which are expressed on, or secreted by, activated macrophages, natural killer (NK) cells, and cytotoxic lymphocytes (CTLs) (Tollefson et al., Nature 392:727-730, 1998). The E3-gpl9K protein inhibits CTL-killing of infected cells by blocking transport of MHC class I antigens to the cell surface (Wold et al., supra). Thus, it is believed that infection of tumor cells by such viral vectors will stimulate infiltration of inflammatory cells and lymphocytes into the tumor, and will not prevent infected tumor cells from apoptosis induced by cytolytic cells of the immune system, or against apoptosis inducing cytokines. For example, it is known that when mice are infected with Ad mutants lacking the E3 gpl9K, RED and 14.7K proteins there is a dramatic increase (as compared to E3 -positive Ad) in infiltration of inflammatory cells and lymphocytes into the infected tissue (Sparer et al., J. Virol. 70:2431- 2439, 1996). A similar infiltration of tumors infected by an ADP-expressing viral vector of the invention would be expected to further promote destruction of the tumor by adding an immune system attack to the ADP-mediated killing activity. For example, it is believed that the viral infection will stimulate formation of tumor-specific CTL's that can kill neoplastic cells not only in the tumor but also ones that have metastasized. In addition, it is also expected that vector-specific CTL's will be generated which could attack vector-infected cells if the vector spreads away from the tumor into normal cells. Because viral vectors overexpressing ADP will spread rapidly through the tumor, it is believed these immune mechanisms will have little effect on spread of the vector. Where the vector is a recombinant adenovirus, it is preferred that the adenovirus lack expression of each of the E3 gpl9K, RED, and 14.7K proteins. By "lack expression" and "lacking expression" of a protein(s), it is meant that the viral genome contains one or more mutations that inactivates expression of a functional protein, i.e., one having all the functions of the wild-type protein. The inactivating mutation includes but is not limited to substitution or deletion of one or more nucleotides in the encoding gene(s) that prevents expression of functional transcripts or that results in transcripts encoding nonfunctional translation products. A particularly preferred way to inactivate expression of the Ad E3 gpl9K, RED, and 14.7K proteins is by deleting the E3 region containing the genes encoding these proteins. Preferably, one or both of the E3 genes encoding the E3 6.7K and 12.5K proteins are also deleted because, as discussed in the Examples below, it is believed that deletion of most or all of the E3 genes other than the ADP gene facilitates overexpression of ADP mRNA by reducing competition for splicing of the major late pre-mRNAs. Preferred Ad vectors containing an E3 deletion that overexpress ADP are GZl (SEQ ED NO:3) and GZ3 (SEQ ED NO:4), whose construction and properties are described in the Examples below. The invention also provides ADP-expressing vectors whose replication is restricted to dividing cells. Any means known to provide such a replication-restricted phenotype may be used. For example, WO 96/40238 describes microbes that preferentially invade tumor cells as well as methods for identifying and isolating bacterial promoters that are selectively activated in tumors. It is also contemplated that expression of one or more vector proteins essential for replication can be placed under the control of the promoter for a cellular gene whose expression is known to be upregulated in neoplastic cells. Examples of such genes include but are not limited to: the breast cancer markers mammaglobin (Watson et al., Oncogene 76:817-824, 1998); BRCA1 (Norris et al., J. Biol. Chem. 270:22777-22782, 1995) her2/neu (Scott et al., J. Biol. Chem. 269:19848-19858, 1994); prostate specific antigen (U.S. Patent 5,698,443); surfactant protein B for lung alveoli (Yan et al., J. Biol. Chem. 270:24852- 24857, 1995); factor VH for liver (Greenberg et al., Proc. Natl. Acad. Sci. USA 92:12347- 12351, 1995); and survivin for cancer in general (Li et al., Nature 596:580-584). Where the vector is an adenovirus, it is contemplated that such tumor-specific promoters can be substituted for the E4 promoter. Because E4 gene products are essential for Ad replication, placing their expression under the control of a tumor-specific promoter should restrict replication of the vector to tumor cells in which the promoter is activated. Another strategy for restricting replication of ADP-expressing Ad vectors to neoplastic cells is exemplified by the KDl (SEQ ED NO:l), KD2 (SEQ ED NO:13) and KD3 (SEQ ED NO:2) vectors, whose construction and properties are described in the Examples below. This strategy exploits a pre-existing Ad5 mutant in the EIA gene, named dll 101/1107 (Howe et al., Proc. Natl. Acad. Sci., 57:5883-5887, 1990), also referred to herein as .7/01/07, and which can only grow well in cancer cells. The role of EIA is to drive cells from the G 0 and Gi phases of the cell cycle into S-phase. This is achieved by two mechanisms, one involving pRB (and family members), and the other involving p300 and the related protein CBP (DePinho, R.A., Nature 597:533-536, 1998). One domain in EIA binds members of the pRB family. pRB normally exists in the cell as a complex with the transcription factor E2F-1 and E2F family members (E2F), tethered via E2F to E2F binding sites in promoters of cells expressed in S-phase. Here, pRB acts as a transcriptional co-repressor. EIA binding to pRB relieves this repression, and causes the release of E2F from pRB/E2F complexes. Free E2F then activates promoters of genes expressed in S-phase, e.g. thymidine kinase, ribonucleotide reductase, etc. Another domain in EIA binds the p300/CBP transcription adaptor protein complex. p300/CBP is a transcriptional co-activator that binds many different transcription factors and accordingly is targeted to promoters. p300/CBP has intrinsic histone acetyltransferase activity. EIA binding to p300/CBP is believed to inhibit this histone acetyltransferase activity, allowing acetylation of histones and repression of transcription (Chakravarti et al., Cell 96:393-403, 1999; Hamamori et al., Cell 96:405-413, 1999). Conceivably, some of the genes that are repressed as a result of El A interacting with p300/CBP to play a role in blocking the cell cycle, although this is not known. Cancer cells are cycling, so they have free E2F and presumably some p300/CBP-regulated genes are repressed. Consistent with these ideas, EIA must bind both p300/CBP and the pRB family in order to transform primary cells to a constitutively cycling state (Howe et al., supra). The mutant .7/01/07 lacks both the p300/CBP- and pRB-binding domains and, as expected, it replicates very poorly in non-dividing "normal" cells or serum-starved cancer cells, but well in growing cancer cells. As described below, the growth of the KDl and KD3 vectors, which contain the .7/01/07 EIA mutation, is very much better in dividing cancer cells as compared to non-dividing cells. Because the .7/01/07 mutant is completely defective in oncogenic transformation of rat cells (Howe et la., supra), vectors according to the invention that contain this EIA mutation cannot induce cancer m humans (remote as that may be) through an E1A- dependent mechanism. The invention also includes vectors overexpressing ADP whose replication is restπcted to specific tissues by placing expression of one or more proteins essential for replication under the control of a tissue specific promoter and/or a tumor specific promoter. A number of tissue-specific and/or tumor specific promoters have been descπbed m the art. Non-hmitmg examples include the surfactant protein B promoter, which is only active in cells containing the TTF1 transcπption factor (i.e., type II alveolar cells (Yan et al., supra)), as descπbed m U.S. Patent 5,466,596 to Breitman et al., which directs gene expression specifically m cells of endothelial lineage; prostate specific antigen which is expressed in prostate cells (Rodriguez et al., supra); human telomerase protein (hTERT) promoter (see, e g., U.S. Patent No. 6,054,575); and human alpha-lactalbumm gene which is expressed in breast cancer cells (Anderson et al., Gene Therapy 6:854-864, 1999). Many other tissue- specific, rumor specific, or tissue-preferred enhancer/promoters have been reported (Miller and Whelan, Human Gene Therapy 5:803-815, 1997). As exemplified with the surfactant protein B promoter in Examples 6 and 10, vectors expressing tissue-specific promoters would be expected to show tissue specificity in viral replication, viral spreadmg, cell lysis, and tumor suppression. Replication of vectors according to the invention can also be controlled by placmg one or more genes essential for vector replication under the control of a promoter that is activated by an exogenous inducing agent, such as metals, hormones, antibiotics, and temperature changes. Examples of such inducible promoters include but are not limited to metallothionein promoters, the glucocorticoid promoter, the tetracycline response promoter, and heat shock protein (hsp) promoters such as the hsp 65 and 70 promoters. The invention also provides compositions compnsmg a recombinant vector that overexpresses ADP in an amount effective for promoting death of neoplastic cells and a method compnsmg administering a therapeutically effective amount of the vector to a neoplastic cell in a patient. It is believed the compositions and methods of the present invention are useful for killing neoplastic cells of any oπgin and include neoplastic cells compnsmg tumors as well as metastatic neoplastic cells. It is also contemplated that ADP-expressing viral vectors can be administered to neoplastic cells along with a replication-defective virus that expresses an anti-cancer gene product. For example, many replication-defective El " Ad vectors for use in cancer therapy are well characteπzed. A limitation of replication-defective vectors is that they only synthesize the therapeutic protein m the cell they initially infect, they cannot spread to other cells. Also, since the genome does not replicate, transcπption can only occur from the input genomes, and this could be as low as one copy per cell. In contrast, the genome of replication-competent Ad vectors are amplified by about 10 4 in the cell that was initially infected, providing more templates for transcription. More amplification is achieved as the vector spreads to other cells. By combining replication-defective viral vectors expressing an anti-cancer gene product with replication-competent viral vectors described herein, it is expected that the result will be template amplification and rapid spread of both vectors to surrounding cells. For example, with Ad-based vectors, the burst size for each vector should be large, ~10 4 PFU/cell, so the probability of co-infection of surrounding cells by both vectors will be high. Thus, both the replication-competent and replication-defective vectors should spread simultaneously through the tumor, providing even more effective anti-cancer therapy. As an alternative method of delivering an anti-cancer gene product with an ADP overexpressing Ad vector, the anti-cancer gene can be engineered into any of the ADP overexpressing replication-competent vectors described herein, in order to provide both the ADP and the anti-cancer function in a single vector. The anti-cancer gene can be engineered into any appropriate location of the vector, as can be easily determined by the skilled artisan. For example, the anti-cancer gene can be engineered into the E3 region. Expression of the anti-cancer gene product encoded by the replication-defective vector can be under the control of either constitutive, inducible or cell-type specific promoters. The anti-cancer gene product can be any substance that promotes death of a neoplastic cell. The term "gene product" as used herein refers to any biological product or products produced as a result of the biochemical reactions that occur under the control of a gene. The gene product can be, for example, an RNA molecule, a peptide, a protein, or a product produced under the control of an enzyme or other molecule that is the initial product of the gene, i.e., a metabolic product. For example, a gene can first control the synthesis of an RNA molecule which is translated by the action of ribosomes into a prodrug converting enzyme which converts a nontoxic prodrug administered to a cancer patient to a cell-killing agent; the RNA molecule, enzyme, and the cell-killing agent generated by the enzyme are all gene products as the term is used here. Examples of anti-cancer gene products include but are not limited to cell-killing agents such as apoptosis-promoting agents and toxins; prodrug converting enzymes; angiogenesis inhibitors; and immunoregulatory molecules and antigens capable of stimulating an immune response, humoral and/or cellular, against the neoplastic cell. Apoptosis-promoting agents include but are not limited to the pro-apoptotic members of the BCL-2 family such as BAX, BAD, BED and BEK, as well as antisense molecules which block expression of anti-apoptotic members of the BCL-2 family. Examples of immunoregulatory molecules are cytokines such as tumor necrosis factor, Fas/Apol/CD95 ligand, tumor necrosis factor related apoptosis inducing ligand, interleukins, macrophage activating factor and interferon γ. Angiogenesis inhibitors include but are not limited to endostatin and angiostatin. Toxins include but are not limited to tumor necrosis factor, lymphotoxin, the plant toxin ricin, which is not toxic to humans due to the lack of ricin receptors in animal cells, and the toxic subunit of bacterial toxins. Examples of pro-drug converting enzymes and pro-drug combinations are described in WO 96/40238 and include thymidine kinase and acyclovir or gancyclovir; and bacterial cytosine deaminase and 5- fluorocytosine. The therapeutic or pharmaceutical compositions of the present invention can be administered by any suitable route known in the art including for example by direct injection into a tumor or by other injection routes such as intravenous, subcutaneous, intramuscular, transdermal, intrathecal and intracerebral. Administration can be either rapid as by injection or over a period of time as by slow infusion or administration of slow release formulation. For treating tissues in the central nervous system, administration can be by injection or infusion into the cerebrospinal fluid (CSF). When it is intended that a recombinant vector of the invention be administered to cells in the central nervous system, administration can be with one or more agents capable of promoting penetration of the vector across the blood-brain barrier. Preferably, vectors of the invention are administered with a carrier such as liposomes or polymers containing a targeting moiety to limit delivery of the vector to targeted cells. Examples of targeting moieties include but are not limited to antibodies, ligands or receptors to specific cell surface molecules. Compositions according to the invention can be employed in the form of pharmaceutical preparations. Such preparations are made in a manner well known in the pharmaceutical art. One preferred preparation utilizes a vehicle of physiological saline solution, but it is contemplated that other pharmaceutically acceptable carriers such as physiological concentrations of other non-toxic salts, five percent aqueous glucose solution, sterile water or the like may also be used. It may also be desirable that a suitable buffer be present in the composition. Such solutions can, if desired, be lyophilized and stored in a sterile ampoule ready for reconstitution by the addition of sterile water for ready injection. The primary solvent can be aqueous or alternatively non-aqueous. The carrier can also contain other pharmaceutically-acceptable excipients for modifying or maintaining the pH, osmolarity, viscosity, clarity, color, sterility, stability, rate of dissolution, or odor of the formulation. Similarly, the carrier may contain still other pharmaceutically-acceptable excipients for modifying or maintaining release or absorption or penetration across the blood-brain barrier. Such excipients are those substances usually and customarily employed to formulate dosages for parenteral administration in either unit dosage or multi-dose form or for direct infusion into the cerebrospinal fluid by continuous or periodic infusion. It is also contemplated that certain formulations containing ADP-expressing vectors are to be administered orally. Such formulations are preferably encapsulated and formulated with suitable carriers in solid dosage forms. Some examples of suitable carriers, excipients, and diluents include lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, gelatin, syrup, methyl cellulose, methyl- and propylhydroxybenzoates, talc, magnesium, stearate, water, mineral oil, and the like. The formulations can additionally include lubricating agents, wetting agents, emulsifying and suspending agents, preserving agents, sweetening agents or flavoring agents. The compositions may be formulated so as to provide rapid, sustained, or delayed release of the active ingredients after administration to the patient by employing procedures well known in the art. The formulations can also contain substances that diminish proteolytic degradation and promote absorption such as, for example, surface active agents. The specific dose is calculated according to the approximate body weight or body surface area of the patient or the volume of body space to be occupied. The dose will also be calculated dependent upon the particular route of administration selected. Further refinement of the calculations necessary to determine the appropriate dosage for treatment is routinely made by those of ordinary skill in the art. Such calculations can be made without undue experimentation by one skilled in the art. Exact dosages are determined in conjunction with standard dose-response studies. It will be understood that the amount of the composition actually administered will be determined by a practitioner, in the light of the relevant circumstances including the condition or conditions to be treated, the choice of composition to be administered, the age, weight, and response of the individual patient, the severity of the patient's symptoms, and the chosen route of administration. Dose administration can be repeated depending upon the pharmacokinetic parameters of the dosage formulation and the route of administration used. The invention also contemplates passively immunizing patients who have been treated with a viral vector overexpressing ADP. Passive immunization can include administering to the patient antiserum raised against the viral vector, or gamma-globulin or vector-specific purified polyclonal or monoclonal antibodies isolated from the antiserum. Preferably, the patient is passively immunized after a time period sufficient for the viral vector to replicate in and spread through the tumor. Preferred embodiments of the invention are described in the following examples. Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. It is intended that the specification, together with the examples, be considered exemplary only, with the scope and spirit of the invention being indicated by the claims which follow the examples. Example 1 This example illustrates the construction and characterization of the KDl and KD3 anti-cancer vectors. To construct KDl, the inventors deleted the entire E3 region of a unique plasmid, leaving behind only a unique Pad site for cloning. The starting plasmid was pCRIL purchased from Invitrogen, containing the Ad5 BamHIA fragment having a deletion of all the E3 genes; the E3 deletion is identical to that for KDl and GZ3, the sequences of which are given in SEQ D NO: 1 and SEQ ED NO:4, respectively. The ADP gene from Ad5 was cloned into the Pad site, then built into the E3 region of the genome of the Ad5 EIA mutant named dlOH07. This was done by co-transfecting into human embryonic kidney 293 cells the aforementioned BamHIA fragment containing the ADP gene together with the overlapping EcoRIA restriction fragment obtained from dlOl/07. Complete viral genomes are formed within the cell by overlap recombination between the Ad sequences in the BamHIA fragment in the plasmid and the EcoRIA fragment. KD3 was constructed in the same way except the E3 gene for the 12.5K protein was retained in the starting plasmid. A vector named KD2, which marginally overexpress ADP, was also prepared. Plaques of each recombinant Ad were picked, screened, purified, expanded into CsCl-banded stocks, sequenced, titered, and characterized. GZl and GZ3 are Ad vectors that are identical to KDl and KD3, respectively, except that GZl and GZ3 have wild-type EIA sequences as found in AD5 or in the Ad5 mutant (7/309. GZl and GZ3 were constructed as described for KDl and KD3 except that the EcoRIA fragment of Ad5 was used for GZl and GZ3. KDl and KD3 were characterized in cell culture by infecting the human A549 lung carcinoma cell line with high titer (1-8 x 10 10 plaque forming units [PFU] per ml) virus stocks of one of these recombinant vectors, or with one of the control viruses (7/01/07, (7/309, (7/327, and Ad5 (wt). Fifty PFU per cell were used for each virus. The descriptions of these viruses as well as some other viruses used in these examples are presented in Table 1. Table 1: Description of mutations in viruses: 4* Using a polymerase chain reaction (PCR)-based protocol, an in-frame stop codon was introduced into the gene for the E3-gpl9K protein in the E3 region of the Ad5 mutant dl309 (Jones and Shenk, Cell 77:683-689, 1979). The mutagenesis was conducted using a Sunl- Bstl 1071 fragment, nucleotides 28,390 to 29,012 in the Ad5 genome, which was then substituted for the equivalent fragment in (7/309. (7/01/07 is the parent for KDl and KD3. In turn, the Ad5 mutant named (7/309 is the parent of (7/01/07, i.e. (7/309 is identical to (7/01/07 except that (7/309 does not have the EIA mutation. Both (7/01/07 and (7/309 have deletions of the genes for the E3 REDα, REDβ and 14.7K proteins but retain the gene for ADP. The Ad5 mutant (7/327 has wild-type EIA, it lacks the gene for ADP, and its lacks all other E3 genes except the one for the 12.5K protein. At 24 and 36 hours post-infection (h p.i.), proteins were extracted from the A549 cells and analyzed for ADP by immunoblot using a rabbit antiserum against ADP (Tollefson et al., J. Virol. 6 ' 6 ' :3633-3642, 1992). The results are shown in Figure 2. Much more ADP was detected at 24 and 36 h p.i. in KDl- and KD3-infected cells than in cells infected with (7/01/07. Also, much more ADP was synthesized by GZl and GZ3 than (7/309 or the other viruses. Most importantly, KDl, KD3, GZl, and GZ3 expressed much more ADP at 24 h p.i. than did (7/01/07 or (7/309 (Fig. 2). This result is consistent with an observation discussed below that the cells infected with KDl, KD3, GZl, or GZ3 lyse faster, and that these viruses spread from cell to cell faster than (7/01/07 or (7/309. It is noteworthy that KDl, KD3, GZl, and GZ3 express much more ADP at 24 and 36 h p.i. than the Ad5 mutant (7/1520 (Fig. 2); (7/1520 is the original name given to ONYX-015 (Heise et al., Nature Medicine 3:639-645, 1997). As expected, no ADP was detected in cells infected with »m734.1 (Fig. 2), a mutant that lacks amino acids 1 to 48 in ADP (Tollefson et al., J. Virol. 70:2296-2306, 1996). Expression of the EIA proteins by (7/01/07, KDl, KD2, and KD3 was slightly less than by Ad5, (7/309, or (7/327, and as expected from the (7/01/07 deletion, the proteins were smaller (Fig. 3A). (7/327 is isogenic with (7/324 (Thimmappaya et al., 1982 Cell 37:543-51, 1983), and it lacks the gene for ADP and all other E3 proteins except the 12.5K protein. The amount of ADP detected in the KDl and KD3 infected cells is significantly higher than the amount detected in the (7/309 infected cells (Fig. 2). If one takes into consideration the fact that the viruses with the EIA mutation replicate somewhat slower, as evidenced in by the delayed appearance of the late proteins (Fig. 3B), it is clear that KDl and KD3 express much more ADP per viral genome present in the cell than (7/309. This finding is supported by the fact that when A549 cells are coinfected with a virus containing the EIA mutation and (7/327, which lacks ADP but has wild-type EIA, the replication rates of the EIA mutant viruses speed up, as indicated by earlier appearance of late proteins (compare Figs. 3B and 3D). Thus, (7/327 complements the El A mutation. In conclusion, these experiments demonstrate that ADP is dramatically overexpressed by KDl, KD3, GZl, and GZ3. ADP is marginally overexpressed by KD2 (not shown). Example 2 This example illustrates that KDl and KD3 lyse cells more rapidly and spread from cell-to cell faster than other adenoviruses. The ability of KDl and KD3 to lyse cells was examined by a trypan blue exclusion cell viability assay which was performed essentially as described by Tollefson et al., J. Virol. 70:2296-2306, 1996. In brief, A549 cells were mock-infected or infected with 20 PFU/cell of KDl, KD3, (7/01/07, <7/327 or (7/309. At various days p.i., the number of viable cells was determined using a hemocytometer (600 to 1000 cells were counted per time point) and the results are shown in Fig. 4. Only 25% of the KDl-infected cells and 9% of the KD3-infected cells were alive at 5 days p.i. as compared to 44% of cells infected with (7/01/07, which has the same EIA mutation as KD 1 and KD3. The KD 1 and KD3 vectors also lysed cells faster than (7/309, which has a wild-type EIA region. When infected with (7/327 (ADP " , EIA*), 94% of the cells were alive after 5 days. When cell lysis was estimated by release of lactate dehydrogenase, KDl and KD3 once again lysed cells faster than (7/01/07 and (7/309, and (7/327 caused little cell lysis (data not shown). Thus, ADP is required for efficient cell lysis, and over-expression of ADP increases the rate of cell lysis. As another means to measure cell lysis and to examine virus replication in cancer cells, separate groups of A549 cells were infected with 20 PFU/cell of KDl, KD3, (7/01/07, or <7/309 and the amount of intracellular and extracellular virus was determined by plaque assay on A549 cells. At 2 days p.i., the total amount of virus formed in each group was similar, 2-4 x 10 8 PFU/ml, indicating that replication of all the viruses is similar. However, when the ratio of extracellular to intracellular virus was calculated, the value for KDl and KD3 was 2-3 logs higher than for Ad5, (7/309, or (7/01/07 (data not shown). Thus, virus is released much more rapidly from cells infected with KDl and KD3, which overexpress ADP, than with viruses expressing wild-type amounts of ADP. The ability of KDl and KD3 to spread from cell-to-cell was measured in a "cell spreading" assay. In this assay monolayers of A549 cells in a 48 well culture dish were mock- infected or infected with 10 3 , 10 -2 , 10 "1 , 10°, or 10 PFU/cell of (7/327, (7/309, Ad5, (7/01/07, KDl or KD3. At low PFU/cell, the viruses must go through two or three rounds of replication in order to infect every cell in the monolayer. At 1.0 and 10 PFU/cell, the monolayer should be destroyed by the virus that initially infected the cells. To assess the amount of spread in the monolayers by 7 days p.i., crystal violet, which stains live cells but not dead cells, was added to the monolayers. The results are shown in Fig. 5. Remarkably, at 7 days p.i., the monolayer was virtually eliminated by KDl and KD3 at 10 "3 PFU/cell, whereas 1.0 PFU/cell was required with (7/01/07, (7/309 and Ad5. This result attests to the potency of ADP in mediating cell lysis and virus spread in A549 cells. KDl and KD3 are also more effective that (7/01/07 in killing other types of human cancer cell lines (most purchased from the American Type Culture Collection [ATCC]) as determined in this cell spreading assay. KDl and/or KD3 killed HeLa (cervical carcinoma), DU145 (prostate), and pC3 (prostate) cells at 10 "2 PFU/cell, ME-180 (cervix) and Hep3B (liver) at 10 "1 PFU/cell, and UI 18 (glioblastoma) and U373 (glioblastoma) at 10 PFU/cell. From 10- to 100-fold more (7/01/07 was required to kill these cells (data not shown). These results indicate that KDl and KD3 may be effective against many types of cancer. An important aspect of the finding that ADP overexpressing vectors lyse cells at very low multiplicities of infection is that the multiplicity of infection in human tumors is likely to be low at sites distal to the sight of vector injection or distal to blood vessels that carry the vector to the tumor. Thus, ADP overexpressing vectors have an advantage over vectors that express less ADP or no ADP at all. Example 3 This example illustrates that KDl and KD3 replicate poorly in non-growing non- cancerous cells. The replication phenotype of KDl and KD3 was evaluated using "normal" HEL-299 human fibroblast cells, either growing in 10% serum or rendered quiescent using 0.1%) serum. All Ads should replicate well in growing cells, but viruses with the (7/01/07 EIA mutation should do poorly in quiescent cells because EIA is required to drive them out of G 0 . (7/309, which has wild-type EIA, should replicate well in both growing and growth-arrested cells. Cells were infected with 100 PFU/cell of KDl, KD3, (7/01/07, or (7/309. At different days p.i., virus was extracted and titered. In 10% serum, KDl, KD3, and (7/01/07 replicated well, reaching titers of 10 6 -10 7 PFU/ml, only slightly less than (7/309 (Fig. 6). However, in quiescent cells, replication of KDl, KD3, and (7/01/07 was 1.5-2 logs lower than in growing cells, ranging from 10 4 to 2 x 10 5 PFU/ml. The titer of (7/309 reached 10 7 PFU/ml, nearly the level achieved in growing cells. At 10 days p.i., quiescent HEL-299 cell monolayers infected with 100 PFU/cell of KDl, KD3, or (7/01/07 were intact, whereas those infected with (7/309 or (7/327, which have wild-type EIA, showed strong typical Ad cytopathic effect indicative of cell death (data not shown). Thus, replication of KDl and KD3 is severely restricted to growing cell lines. The restriction associated with the (7/01/07 EIA mutation was also tested in primary human cells (purchased from Clonetics) growing as monolayers. Bronchial epithelial cells (Fig. 7) and small airway epithelial cells were not killed by 10 PFU/cell of KDl, KD3, or (7/01/07 at 5 days p.i., whereas they were killed by 10 PFU/cell of (7/309 or (7/327 (data not shown). Lung endothelial cells also were not killed after 10 days by KDl, KD3, or (7/01/07 at 10 PFU/cell, but they were killed by 1 PFU/cell of (7/309. These monolayers were subconfluent when initially infected, then grew to confluency. The exciting result here is that although these primary cells were growing, they did not support replication in this time frame and were not killed by KDl or KD3. Thus, it is believed these vectors will be restricted to cancerous cells, and will have little to no effect on cells such as basal cells that are normally dividing in the body. In addition, it is unlikely that KDl and KD3 will affect dividing leukocytes because such cells are poorly infected by Ad. In summary, the above experiments demonstrate that KDl and KD3 lyse cancer cells, spread from cell-to-cell rapidly, and replicate poorly in quiescent and non-cancerous cells. These properties should make them useful in anti-cancer therapy. Example 4 This example illustrates that KDl and KD3 inhibit the growth of human tumors in an animal model. We could not evaluate mouse or rat tumors in normal mice or rats because they are totally non-permissive. Human cancer cell lines growing in nude mice have been used by Onyx Pharmaceuticals (Richmond, CA) to evaluate the efficacy of ONYX-015, an Ad vector lacking expression of the EIB 55 kDa protein (Heise et al., Nature Med. 3:639-645, 1997). We have found that A549 cells, which were used in many of our cell culture studies, form excellent rapidly growing solid tumors when injected subcutaneously into nude mice. The average tumor reaches ca. 500 μl in four weeks, and is encapsulated, vascularized, and attached to the mouse skin (usually) or muscle. Nude mice were inoculated into each hind flank with 2 x 10 7 A549 cells. After 1 week tumors had formed, ranging in size from about 20 μl to 50 μl. Individual tumors were injected three days later, and at subsequent weeks for 4 weeks (total of 5 injections), with 50 μl of buffer or 50 μl of buffer containing 5 x 10 7 PFU of (7/309, (7/01/07, KDl, KD3, or pm734.l, with a total virus dose per tumor of 3 x 10 8 PFU. The mutant pm734.l lacks ADP activity due to two nonsense mutations in the gene for ADP, but all other Ad proteins are expected to be synthesized at wild-type levels (Tollefson et al., J. Virol. 70:2296-2306, 1996). The efficacy of each virus (or buffer) was tested on six tumors. At weekly intervals, the length (L) and width (W) of tumors were measured using a Mitutoyo digital caliper. Tumor volumes were calculated by multiplying L x W x W/2. This value was divided by the tumor volume at the time of the initial virus injection, the fold-increase in tumor growth was calculated, and the average for the six tumors was graphed. As shown in Fig. 8A, tumors that received buffer continued to grow, increasing about 14-fold by 5 weeks. In contrast, tumors injected with (7/309, which expresses normal amounts of ADP and lacks the E3 RED and 14 7K and proteins, only grew about 2.5-fold by 5 weeks. With ?w734.1, which lacks ADP, the tumors grew as well as those that received buffer. Thus, (7/309 markedly decreases the rate of tumor growth, and ADP is required for this decrease Tumors inoculated with (7/01/07 grew about 8-fold over 5 weeks. Smce (7/01/07 is identical to (7/309 except for the El A mutation, this result indicates that the El A mutation significantly reduces the ability of Ad to prevent growth of the tumors. This effect is probably due to a reduction m virus replication in the tumors resulting in lower ADP expression, but it could also reflect other properties of El A in the tumor cells, e.g. the inability of the mutant EIA proteins to induce apoptosis. Most importantly, tumors inoculated with KDl or KD3 only grew about 2.5-fold. Thus, the overexpression of ADP by KDl and KD3 allows KDl and KD3 to reduce tumor growth to a rate markedly slower than (7/01/07 (their parental control virus), and even to a rate similar to that of (7/309. The finding that KDl and KD3 are as effective as wild-type Ad (i.e. (7/309) in reducing the rate of A549 tumor growth is highly significant in the context of cancer treatment, inasmuch as KDl and KD3 are restπcted to cancer cells whereas wild-type Ad does not have such a restriction. The tumors in Fig. 8 A received five injections of vectors, but only one dose of vector, in this case 5 x 10 8 of each of KD3 or GZ3, is sufficient to significantly reduce the rate of A549 tumor growth (Fig. 8B). We have also found that KD 1 and KD3 reduce the rate of growth m nude mice of a human liver cancer cell line, Hep3B cells. These cells form rapidly growing tumors that are highly vasculaπzed. Nude mice were inoculated into each hind flank with 1 x 10 7 of Hep3B cells. After tumors reached about 100 μl, they were injected twice per week for 3 weeks with 50μl of buffer or 5 x 10 7 PFU of KDl, KD3, or (7/309. There were typically 8-10 tumors per test virus. The tumor sizes were measured and the fold increase in size at 0 to 3.5 following the initial virus injection was graphed as descπbed above for the A549 tumors. Tumors that received buffer alone grew 9-fold over 3 weeks and were projected to grow about 12-fold over 3.5 weeks (after 3 weeks the mice had to be sacπficed because the tumors were becoming too large) (Fig. 9). Tumors that received KDl or KD3 grew about 4-fold, establishing that KDl and KD3 reduce the growth of Hep3B tumors in nude mice. Tumors that were injected with (7/309 grew 2-fold (Fig. 9). The finding that KDl and KD3 were somewhat less effective than (7/309 is probably due to the fact that they do not grow as well as (7/309 in Hep3B cells, as indicated by a cell spread assay in culture (data not shown). In any case, the important points are that KDl and KD3 are effective against the Hep3B tumors, and that they contain the EIA mutation that limits their replication to cancer cells. These results point to the potency of ADP as an anti-tumor agent when expressed in an Ad vector. It is highly probable that KDl and KD3 will provide significant clinical benefit when used to infect tumors growing in humans. Example 5 This example illustrates the use of replication-defective Ad vectors in combination with KDl or KD3. It is well established that replication-competent (RC) viruses complement replication- defective (RD) mutants. That is, when the same cell is infected, the competent virus will supply the protein(s) that cannot be made from the mutant genome, and both viruses will grow. To test the ability of KDl and KD3 to complement RD viruses, two RD vectors expressing β-galactosidase were constructed. The first, named Ad-β-gal, has a cDNA encoding β-gal under the control of the Rous Sarcoma Virus promoter substituted for the deleted El region. Ad-β-gal also has the E3 region deleted, including the gene for ADP. The second, named Ad-β-gal/FasL is identical to Ad-β-gal, except that it also expresses murine FasL from the human cytomegalovirus promoter/enhancer. These vectors were constructed by overlap recombination in human 293 cells that constitutively express the Ad EIA and EIB genes and complement replication of the El -minus vectors. These RD vectors should infect and express β-gal in A549 cells, but should not replicate because the EIA proteins are lacking. However, the vectors should replicate when cells are co-infected with RC Ads. To prove this, A549 cells were infected with 10 PFU/cell of Ad-β-gal alone, or with 10 PFU/cell of Ad-β-gal plus 10 PFU/cell of KDl, KD3, (7/01/07, (7/309, or (7/327. At 2 days p.i., virus was extracted and Ad-β-gal titers determined by β-gal expression in A549 cells. The yields are shown in Table 2 below. Table 2 The data in Table 2 indicate that the complementing viruses increased the yield of Ad-β-gal by about 10 3 . A key feature of KDl and KD3 is that they spread from cell-to-cell faster than other Ads. Accordingly, they should complement the spread of Ad-β-gal. To test this, an infectious center assay was conducted. A549 cells were infected with Ad-β-gal plus KDl, KD3, or (7/01/07. After 2 h, cells were collected, diluted, and seeded onto monolayers of fresh A549 cells. After 4 days, the cells were stained with X-gal and the results are shown in Fig. 10. With Ad-β-gal alone, only the originally infected cell (before seeding) should be stained, and the vector should not spread to other cells on the seeded monolayer. This was indeed the case. In monolayers seeded with A549 cells infected with Ad-β-gal alone (dish shown in the top left of Fig. 10A) contained a number of individual blue cells (not visible in the print); examples are shown in the enlarged view Fig. 10B. However, when the monolayers were seeded with A549 cells coinfected with Ad-β-gal and KDl or KD3, there were numerous "comets" of blue cells (Fig. 10A). Each comet represents Ad-β-gal which has spread from one initially-infected cell. Most of the cells within a comet were stained with X- gal (Fig. 10C). Comets were also observed with (7/01/07, but not to the extent of KDl and KD3 (Fig. 10A). With (7/327 (ADP " ), there was little spread from the originally infected cell (data not shown). In summary, KDl and KD3 not only complement the replication of Ad-β- gal, they also enhance its rapid spread. It is expected that KDl and KD3 will also complement and enhance the spread of RD vectors expressing anti-cancer therapeutic gene products, and this expectation can be readily veπfied using the Ad-β-gal/FasL m replication and infectious center assays as descπbed above. KDl and KD3 not only complement the replication of RD vectors in cell culture, they also do so in Hep3B tumors growing m the hind flanks of nude mice. The RD vector used was AdLuc, an Ad that lacks the El and E3 regions, and has inserted into the El region an expression cassette where the firefly luciferase gene is expressed from the Rous Sarcoma Virus promoter (Harrod et al., Human Gene Therapy 9: 1885- 1898, 1998). The Hep3B tumors were injected with 1 x 10 7 PFU of AdLuc plus buffer, or 1 x 10 7 PFU of AdLuc plus 5 x 10 7 PFU of KDl, KD3, (7/01/07, or (7/309. After 2 weeks, mice were sacπficed and tumors excised. Proteins were extracted from the tumors and luciferase activity determined using a luminometer. The luciferase counts per tumor were 6,800 for AdLuc plus buffer, 113,500 for KDl, and 146,900 for KD3 (Fig. 11). Thus, KD3 and KDl respectively caused a 22-fold and 17-fold increase m luciferase activity. This increase could be due to elevated synthesis of luciferase in cells that were initially comfected the AdLuc and KDl or KD3, and it could also be due to spread of AdLuc from cell to cell m the tumor as mediated by KDl or KD3. In summary, infecting a tumor with a replication-competent ADP-overexpressmg vector according to the invention together with a RD vector expressing an anti-cancer gene product should greatly increase the amount of anti-cancer protein synthesized in the tumor thereby increasing the ability of the replication-defective vector to promote destruction of the tumor. Example 6 This example illustrates the construction and characteπzation of a recombinant Ad vector according to the invention which is replication-restricted to cancerous type II alveolar cells. As demonstrated above, the (7/01/07 mutation m KDl and KD3 limits growth of these vectors to cancer cells. To further restrict their replication phenotype, the E4 promoter in each virus was deleted and replaced by the surfactant protein B (SPB) promoter to produce vectors named KDl-SPB (SEQ ED NO: 14), KD3-SPB (SEQ ED NO: 15), and (//01/07-SPB (SEQ ID NO:16). The SPB promoter is only active m cells containing the TTFl transcπption factor, which has thus far been found pπmaπly m type II alveolar cells of the human lung (Lazzaro et al., Development 773:1093-1104, 1991). Thus, KDl-SPB, KD3-SPB, and <7/01/07-SPB should be severely restπcted to cancerous type ϋ alveolar cells of the human lung. Many lung cancers are of this type. The KDl-SPB and KD3-SPB vectors were prepared as follows. The E4 promoter is located at the πght end of the Ad genome (Fig. 1). Using a pCREI-based plasmid (Invitrogen) containing the Ad5 DNA sequences from the BamHI site (59 map units) to the πght hand end of the genome, and using and a PCR-based protocol, nearly all the transcπption factor binding sites were deleted from the E4 promoter Ad5 base pairs 35,623 to 35,775 and replaced with a 500 base pair fragment containing the SPB promoter (Yan et al., J. Biol. Chem. 270:24852- 24857, 1995). The final plasmids contain the E4-SPB substitution in the E4 region and the (7/01/07, KDl, or KD3 versions of the E3 region, respectively, for the viruses (7/01/07-SPB, KDl-SPB, and KD3-SPB. These plasmids were co-transfected into 293 cells with a fragment containing the left portion of the genome of (7/01/07, and plaques were allowed to develop. Plaques were screened for the expected features, puπfied, then expanded into a stock. The A549-TTF1 cell line was developed m order to test the prediction that replication of (7/01/07-SPB, KDl-SPB, and KD3-SPB would be restπcted to cancerous cells expressing the TTFl transcπption factor. These cells were co-transfected with two plasmids, one m which TTFl is expressed from the CMV promoter, and the other coding for resistance to neomycin Resistant clones were isolated and shown to express TTFl activity as determined by transient transfection with a plasmid expressing chloramphemcol acetyltransferase from the TTFl-requiπng surfactant protein C promoter. KDl-SPB and KDl were subjected to a standard plaque development assay on A549- TTF1 cells and parental A549 cells. The results are shown in Fig. 12. With KDl-SPB on A549 cells, plaques were not visible after 8 days, only about 4% of the final number of plaques were seen after 10 days, and about 50% of final plaques were seen after 12 days. With KDl-SPB on A549-TTF1 cells, plaques were visible after 6 days, and about 60% of plaques were seen after 10 days. Thus, as expected, KDl-SPB grew significantly faster on the cells containing TTFl . KDl formed plaques more quickly than KDl-SPB on both A549 and A549-TTF1 cells, indicating that the E4 promoter-SPB substitution is not as effective the wild-type E4 promoter m inducing Ad replication. However, this difference between KDl- SPB and KDl on A549-TTF1 cells is tolerable, with KDl-SPB delayed only about 1 day. Cuπously, the final titer obtained for all virus stocks by day 16 was similar, indicating that A549 cells may contain a very small amount of endogenous TTFl activity. It is predicted that KD3-SPB and (7/01/07-SPB will behave similarly to KDl-SPB when grown in A549-TTF1 cells and A549 cells. The restriction of KDl-SPB to cells containing TTFl was further examined in a cell spread assay using H441 cells, a TTFl -expressing human pulmonary adenocarcmoma cell line (Yan et al., supra), and Hep3B cells, a liver cancer cell line not expected to express TTFl. Culture dish wells containing H441 or Hep3B cells were infected with KDl-SPB or KDl at multiplicities ranging from 10 to 10 "4 PFU/cell. The H441 and Hep3B cells were stained with crystal violet at 5 days and 8 days p.i., respectively. KDl-SPB and KDl grew and spread equally well on H441 cells, causing destruction of the monolayer at 10 " ' PFU per cell (Fig. 13). (Some of the H441 monolayer has peeled off in the well with KDl-SPB at 10 "2 PFU per cell, and m the wells with KDl and KDl-SPB at 10 "4 PFU per cell; this occasionally occurs in cell spread assays, and it does not reflect virus infection). With Hep3B cells, KDl grew and spread very much better than KDl-SPB, with 10 2 PFU per cell of KDl causing more destruction of the monolayer as 1.0 PFU per cell of KDl-SPB (Fig. 13). In summary, this example demonstrates that a replication-competent Ad, which replicates well on cells expressing the appropπate transcπption factor, can be constructed with a tissue-specific promoter substituted in place of the E4 promoter. This methodology should be applicable to many other tissue specific and cell type specific promoters. One possibility would be a liver-specific promoter. Another possibility would be to use the E2F promoter, or another promoter with E2F sites, inasmuch as that promoter would be active only m cells such as cancer cells that have free E2F. A third possibility would be to use a regulatable promoter, e.g. the synthetic tetracycline response promoter (Massie et al., J. Virol. 72 2289-2296, 1998), where the activity of the promoter is controlled by the level of tetracycline or a tetracyclm analog in the patient. Example 7 This example illustrates the construction and characteπzation of vectors which overexpress ADP and are not replication restncted. As demonstrated above, the (7/01/07 EIA mutation in KDl and KD3 is attenuating, inhibiting growth m non-dividmg and even m dividing pπmary human epithelial and endothelial cells. Ads with this mutation are able to replicate well in dividing cancer cells. However, replication of such EIA mutants is not as efficient as, e.g. (7/309 which has a wild- type EIA gene. For instance, the rate of replication of (7/01/07, as determmed by the rate at which plaques develop, is reduced such that (7/01/07 plaques appear one day later than those of (7/309 (data not shown). This delay is due in part to a delay in expression of Ad late genes (see Fig. 3). The idea that the (7/01/07 mutation retards the rate of replication in A549 cells is further supported by the data in Fig. 8 A, where (7/01/07 did not prevent tumor growth nearly as well as (7/309. Despite this negative effect of the (7/01/07 EIA mutation, there are theoretical and practical aspects of having this mutation in the KDl and KD3 vectors, as has been discussed. Nevertheless, one can easily imagine scenaπos (e.g. patients with terminal cancer) where the ability of an Ad vector to destroy the tumor supercedes the requirement that the vector be totally restπcted to tumor cells. In such cases, it would be advantageous to have vectors similar to KDl and KD3, but with the wild-type EIA gene. The rates at which such vectors express their genes, lyse cells, and spread from cell to cell should be higher than those of KDl and KD3. Such vectors might cause some damage to non-cancerous cells and tissue, but this is also true for other modes of anti-cancer treatment such as surgery, chemotherapy, and radiation therapy. In light of these considerations, vectors named GZl and GZ3 have been constructed that are identical to KDl and KD3, respectively, except they have a wild-type EIA region. These vectors were constructed by overlap recombination in A549 cells. The left hand fragment contained the wild-type EIA region of Ad5, and the πght end fragment contained the E3 modifications of KDl or KD3. Plaques were picked, analyzed for the expected genotype, plaque-puπfϊed, and expanded into CsCl-banded stocks. The titers of these stocks on A549 cells were 2.9 x 10 10 PFU/ml for GZl and 1.6 x 10" PFU/ml for GZ3. Thus, these vectors can be grown into high titer stocks comparable to wild-type Ad. The GZl and GZ3 plaques are larger and appear much sooner than the plaques for (7/309. Large rapidly- appeaπng plaques reflect the ability of Ad to lyse cells and spread from cell-to-cell (Tollefson et al, J. Virol. 70:2296-2306, 1996; Tollefson et al., Virology 220:152-162, 1996), and this property, as discussed, is due to the function of ADP. The rate of plaque appearance can be quantitated m a plaque development assay (Tollefson et al., supra). Here, a typical plaque assay is performed, and the plaques observed on subsequent days of the assay are calculated as a percentage of the number of plaques observed at the end of the plaque assay. As shown m Fig. 14, after 4 days of plaque assay on A549 cells, GZl and GZ3 had 48% and 34%, respectively, of the final number of plaques, whereas (7/309 had only 1%. It is very unusual in Ad plaque assays in A549 cells for plaques to appear after only 4 days. These large plaques reflect the overexpression of ADP. These GZl and GZ3 plaques appear sooner than those of KDl and KD3 (data not shown), no doubt because GZl and GZ3 replicate faster because they have a wild-type EIA region. GZl and GZ3 lyse cells and spread from cell to cell much more effectively than (7/309. At 6 days p.i. of A549 cells, approximately as much monolayer destruction was observed with GZl and GZ3 at 10 "3 PFU per cell as was observed with (7/309 at 10 "1 PFU per cell (Fig. 15, top panel). This result further underscores the conclusion that overexpression of ADP promotes cell lysis and virus spread. In theory, GZl and GZ3 should be able to replicate not only in tumor cells but also m normal cells. Although they can replicate m normal cells, it is quite possible that GZl and GZ3 may be useful as anti-cancer vectors. First, GZl and GZ3 could be injected directly into the tumor. Many tumors are self-contained (encapsulated) except for the blood supply. The physical barπers of the tumor could minimize dissemination of the virus to other tissues. Second, Ads are m general quite benign. Most infections of Ad5 are in infants and result m mild or asymptomatic disease, and are held in check by strong humoral and cellular immunity. Anti-Ad immunity appears to be life-long. GZl and GZ3 could be used only m patients who have an mtact immune system, and perhaps also with pre-existing anti- Ad immunity. Further, patients could be passively immunized against Ad, using gamma-globulm or even specific puπfied anti-Ad neutralizing antibodies. Third, consideπng that Ad5 is a respiratory virus which most efficiently infects lung epithelial cells displaying the specific Ad5 receptor (named CAR) as well as specific integrals (e.g. a v b5), replication-competent vectors deπved from Ad5 may not spread efficiently m many non-cancer tissues of the body. In addition, it is believed that versions of GZl and GZ3 can be constructed that have the E4 promoter substituted with a tumor-specific, tissue-specific, cell-specific, or synthetic promoter. Such vectors would have the positive features associated with wild-type EIA and ADP, and yet be rephcation-restπcted to tumor tissue and/or to particular cell types. Example 8 This example illustrates that the combination of KDl, KD3, GZl, or GZ3 with radiation is more effective in destroying A549 cells, growing in culture or growing as tumors m nude mice, than the vectors alone or radiation alone. This was shown m a cell spread assay. A549 cells growing in three 48 well culture dishes were mock-infected or infected with different viruses at multiplicities of infection ranging from 10 to lO^PFU per cell as indicated in Fig. 15. One dish was not radiated. A second dish received 600 centπgreys (cGy) of radiation at 24 h p.i., and a third dish received 2000 cGy of radiation at the same time. All dishes were stained with crystal violet at 6 days p.i. With the cells that were not radiated (top panel m Fig. 15), KDl and KD3 caused monolayer destruction at lower multiplicities of infection than their parental control, (7/01/07. This was also true for GZl and GZ3 as compared to their parental control (7/309. (The paucity of cells in the cells infected with GZl or GZ3 at 10 "4 PFU per cell is an expeπmental artifact, and is not caused by infection by GZl or GZ3). These KDl, KD3, GZl and GZ3 results are consistent with earlier results showing that overexpression of ADP leads to increased cell lysis and virus spread. With the dish that was infected then radiated with 600 cGy there was markedly increased cell killing and virus spread as compared to the non-radiated cells (compare the bottom panel of Fig. 15 with the top panel). For example, with KDl, KD3, GZl, and GZ3 there was about the same amount of cell destruction the radiated wells at 10 "4 PFU per cell as in the non-radiated wells at 10 "2 PFU per cell. Similar results were seen with the dish that received 2000 cGy of radiation (data not shown), and also with dishes that received 600 or 2000 cGy of radiation 24 h pπor to infection (data not shown). The amount of cell destruction was quantitated by extracting the crystal violet from the cells with 33% acetic acid, then measuπng the absorbance at 490 nm (data not shown). The absorbance with non-radiated mock-mfected cells was set at 100% cell viability. With mock-mfected cells that received 600 cGy there was a 15% loss m viability (i.e. 15% less crystal violet was extracted). With KDl at 10 3 PFU per cell, the non-radiated cells were 80% viable whereas the cells receiving 600 cGy of radiation were only about 30% viable. Similar differences m viability between radiated and non-radiated cells were seen with KD3, GZl, and GZ3. These results argue that the combination of radiation plus vector has a syngergistic effect on cell lysis and vector spread, rather than an additive effect. If the effect were only additive, then with the KDl samples at 10 "3 PFU per cell, the cell viability should have been 65% (15% reduction in viability due to radiation alone, 20% reduction due to KDl alone). In fact, the cell viability was 30% rather than 65%. As mentioned, approximately as much cell lysis and virus spread were observed with 600 cGy as with 2000 cGy. To determine the optimal dose of radiation to synergize with the vectors, an expeπment similar to the one descπbed above was conducted with mock-, (//01/07-, KD1-, KD3-, dl309, GZ1-, or GZ3-mfected A549 cells. The 48 well plates received 0, 150, 300, or 600 cGy of radiation at 24 h p.i. Cells were stained with crystal violet. The results with cells receiving 0 versus 600 cGy of radiation were similar to those m Fig. 15. The crystal violet was extracted from the cells infected with 10 "3 PFU per cell of the difference viruses. The absorbance of crystal violet was determined, and the percent cell viability was graphed, using the absorbance of the non-radiated mock-mfected cells as 100% cell viability. As illustrated in Fig. 16, an approximately linear decrease in cell viability m all wells was obtained with increasing radiation dose, although the slope of the line was more negative with KDl, KD3, GZl, or GZ3 than with mock, (7/01/07, or (7/309. With KDl, KD3, GZl, and GZ3, there was much more cell lysis and vector spread with their parental control viruses, and there was synergy between the vectors and radiation. For example, with mock- mfected cells, 600 cGy reduced cell viability by about 30% (70% of cells were viable). KDl without radiation reduced cell viability by about 23%. The combination of 600 cGy radiation plus KDl reduced cell viability to about 85%, more than 53% of which is the sum of radiation alone and KDl alone. When consideπng the data in Figs. 15 and 16 together, a dose of about 600 cGy is optimal this type of cell culture expeπment. The combination of KD3 or GZ3 with radiation was also examined in the A549 tumor-nude mouse model (see Example 4). A549 cells were injected into the hmd flanks of nude mice, and tumors were allowed to form. When tumors reached approximately 50-μl, they were injected with buffer or with 5 x 10 8 PFU of KD3 or GZ3. Eight to ten tumors were injected per test condition At 1 day p.i., half the mice received 600 cGy of whole body radiation. Tumor size was measured over time, and was plotted as a fold-increase m tumor size versus days p.i. (as descπbed m Example 4). As shown m Fig. 17, the non-radiated buffer-mjected tumors grew faster than those injected with KD3 or GZ3. Tumors that received the combination of KD3 and radiation did not grow, and those that received the combination of GZ3 and radiation shrank in size after 14 days. These results mdicate that the combination of KD3 plus radiation or GZ3 plus radiation is more effective than either vector alone or radiation alone m reducing the rate of A549 tumor growth m nude mice. It is likely that radiation would increase the effectiveness in treating tumors of KDl and GZl, or mdeed any other replication-competent or replication-defective Ad vector. The mechanism by which radiation causes the ADP overexpressing vectors to lyse cells and spread from cell-to-cell more effectively is not understood. Radiation is expected to induce cellular DNA repair mechanisms, and that may allow for more efficient synthesis of Ad DNA. Radiation may enhance the function of ADP. ADP probably functions by interacting with one or more cellular proteins, and radiation may affect this protem(s) such that ADP functions more efficiently. It is believed that KDl, KD3, GZl, or GZ3, or any other replication-competent Ad vector, when used m combination with radiation, will be more effective than vector alone or radiation alone m providing clinical benefit to patients with cancer. The vectors should allow more tumor destruction with a given amount of radiation. Stated another way, radiation should cause more tumor destruction with a given amount of vector. These vectors should also allow the radiation oncologist to use less radiation to achieve the same amount of tumor destruction. Less radiation would reduce the side effects of the radiation. It is also believed that a cocktail of vectors when used in combination with radiation will be more effective than the cocktail alone or radiation alone. The cocktail could consist of ADP producing vectors plus one or more replication defective vectors expressing an anticancer therapeutic protein (see Example 5). Example 9 This example illustrates a structure-function analysis of adenovirus death protein. ADP is an 11.6 kDa N-hnked O-linked integral membrane glycoprotem that localizes to the inner nuclear membrane (NM) (Scaπa et al., Virology 191:743-753). As illustrated in Fig. 18, the Ad2-encoded ADP (SEQ ED NO:6) consists of 101 ammo acids; aa 1-40 (SEQ ED NO: 17) are lumenal, aa 41 -59 (SEQ ED NO: 18) constitute the transmembrane signal-anchor (SA) domain, aa 63-70 (SEQ ED NO: 19) constitute a basic prohne (BP) domain withm the nucleoplasmic (NP) domain, which constitutes aa 61-101 (SEQ ED NO:20). To determine which domains in ADP are required to promote cell death, a number of deletion mutants of rec700 were prepared which lacked vaπous portions of the ADP gene and examined for the ability of ADP to localize to the NM and promote death. The rec700 virus is an Ad5-Ad-Ad5 recombmant, which has been descπbed elsewhere (Wold et al., Virology 745:168-180, 1986). The structure of ADP m rec700 and m each deletion mutant is schematically illustrated m Fig. 18. The ADP gene m each deletion mutant has been sequenced using PCR methods to insure that the mutations are correct. The structure and activity of ADP m the deletion mutants was tested by infecting A549 cells followed by immunoblot analysis of the ADP mutant proteins as well as the ability to lyse cells. All deletion mutants expressed a stable ADP protein except pm73AΛ (Δl-48, i.e. aa 1-48 are deleted). The/wz734.7 (N M ) ADP, which has Asn^ mutated to Ser, is O-glycosylated but not N-glycosylated because Asnι 4 is the only N-glycosylation site (data not shown). The (7/735 (Δ4-11) ADP is N- glycosylated but not O-glycosylated because the sites for O-glycosylation are deleted (data not shown). The/wι734.4 (M56) ADP, which has Met 56 m the SA domam mutated to Ser, contains exclusively N-hnked high-mannose ohgosacchaπdes (data not shown); this occurs because the Met 56 mutation precludes exit of ADP from the endoplasmic reticulum (ER). The (7/738 ADP, which lacks aa 46-60 in the signal-anchor domam, forms insoluble aggregates the cytoplasm; therefore, aa 41-59 do in fact include the signal-anchor domam. The/wι734 (Δl-40) ADP, which initiates at Met 41 at the N-terminus of the SA domain, comigrated with the lower group of bands generated by proteolytic processing (data not shown). This indicates that the proteolytic cleavage sites occur near Met 4 ι. Consistent with this, the proteolytic products were not seen with (7/737 (Δ29-45) (data not shown). Also, the size of the products decreased m all mutants with deletions withm aa 41-101 ((7/715.1, (7/715, (7/714, (7/716) (data not shown). The ability of these mutants to promote cell death was monitored by trypan blue exclusion, plaque development, and lactate dehydrogenase release assays (Tollefson et al., J. Virol. 70:2296-2306, 1996). The trypan blue results in Fig. 15A indicate that the death- promoting function of ADP was abolished by deletion of aa 1-40 (pm.734), aa 11-26 ((7/736.1), aa 18-22 ((7/735.1), or aa 4-11 ((7/735). Mutation of the N-glycosylation site at Asn 14 (pm.734.7) reduced the death-promoting activity to about 50% of rec700 (WT). (7/737 (Δ29-45) was efficient as rec700 m promoting cell death; this indicates that the proteolytic processing products must not be required to promote cell death because they are not formed with (7/737. The SA domain is essential for death because (7/738 (Δ46-60) and/?m734.4 (M56) were completely defective (Fig. 19). (7/715.1 was nearly completely defective, indicating that the BP domain is extremely important. Surpπsmgly, aa 71-94 (dl7l4), 76-89 ((7/715), and 79-101 ((7/716) could be deleted without affecting the death-promoting activity of ADP (Fig. 19) On the other hand, deletion of aa 81-88 ((7/717) nearly completely abolished the activity of ADP (Fig. 19); this is probably the result of aberrant sorting of ADP (see below). Similar results were obtained when the ability of these ADP mutants to promote cell death was examined with standard plaque development, LDH-release and MTT assays. The effects of these mutations on the mtracellular localization of ADP are extremely interesting. When examined by immunofluorescence (EF) at 33 h p.i. (data not shown), ADP from rec700 (WT) localized cπsply to the NM; localization to the Golgi was also apparent. With (7/714 (Δ71-94) and (7/715 (Δ76-89), ADP localized to all membranes, i.e. the ER, Golgi, plasma membrane, and NM. This was even more apparent at 45 h p.i. (data not shown) Thus, aa 71-94 appear to include a signal that directs ADP specifically to the NM. ADP is very likely sorted from the trans-Golgi network (TGN) to the NM, so this putative signal m ADP probably functions in this sorting pathway. ADP from (7/717 (Δ81-88) is intriguing: it localized to the NM and Golgi, but m many cells "dots" and circular structures were observed. Again, this was more apparent at 45 h p.i. when these structures were the prominent feature. (7/717-ιnfected cells have not begun to die at 45 h p.i., so these structures are not cellular remnants. The mtπguing possibility is that these structures are membrane vesicles that have pinched off from the TGN but are defective in targeting to and or fusing with the NM. With (7/738 (Δ46-60 in the SA domain), ADP aggregated in the cytoplasm. This again indicates that aa 46-60 include the SA sequence. Wιth/?m734.4 (M56), ADP localized pπmaπly to the NM. As discussed above, thepm73A.A ADP has exclusively high-mannose N-hnked ohgosacchaπdes, indicating that it never leaves the ER. Perhaps the putative NM- localization signal in the C-terminal region of thepm73A 4 ADP targets ADP to the NM by lateral diffusion from the ER (which is continuous with the outer and inner NM). With (7/737 (Δ29-45), ADP localized to the NM. ADP from/wι734 (Δl-40),/vn734.7 (N14) (N-hnked glycosylation cannot occur), and (7/735 (Δ4-11; the O-glycosylation sites are deleted) localized much more prominently to the Golgi than the NM. ADP from (7/735.1 (Δ18-22) and (7/736.1 (Δl 1-26) also localized much more strongly to the Golgi than the NM. Thus, residues 1-26 and/or glycosylation appear to be required for efficient transport of ADP from the Golgi/TGN to the NM. In summary, aa 41-59 include the SA domain, Met 56 in the SA domain is required for exit from the ER, aa 1-26 are required for efficient exit from the Golgi, and aa 76-94 are required to target ADP specifically to the NM. With respect to promoting cell death, the essential regions are aa 1-26, the SA domain (ADP does not enter membranes), Met 56 in the SA domain, and the BP domain (aa 63-70). It is not clear whether the defective death- promoting phenotype ofpm73A (Δl-40), (7/735 (Δ4-11), (7/735.1 (Δ18-22), (7/736.1 (Δl 1-26), andpm73A.7 (N14) is due to lack of sequences (or oligosaccharides) that promote death or to much slower exit of ADP from the Golgi to the NM. (7/714 (Δ71-94) and (7/715 (Δ76-89) express a wild-type phenotype for promoting death even though they are defective in localizing specifically to the NM; this is probably because sufficient ADP still enters the NM to promote death. Even though the deletion in (7/717 (Δ81-88) lies within the deletions in (7/715 (Δ76-89) and (7/714 (Δ71-94), the (7/717 ADP is only about 15% as efficient as rec700 (WT), (7/715 and (7/714 in promoting death. This may be because the (7/717 ADP tends to remain in vesicles rather than localizing to the NM. Altogether, these data indicate that ADP must localize to the NM in order to promote cell death. Example 10 This example further characterizes the tissue specific Ad vectors described in Example 6. As discussed therein, the Ad E4 promoter is deleted and replaced with the promoter for surfactant protein B (SPB) in these vectors (Figure 24). Materials and Methods Cells, vectors and methods described in Example 6 were also used in this Example. In addition to the human cancer cell lines A549 (human lung carcinoma), Hep 3B (human hepatocellular carcinoma), and H441 (papillary lung adenocarcinoma) used in Example 6, HEK 293 cells (obtained from Microbix (Toronto, ON)) and VK10-9 cells were used. VklO- 9 cells are 293 cells that in addition to El contain and express E4 and pEX. These cells will be referred to as 293 -E4 cells. Experiments employing phase contrast microscopy of Hep 3B and H441 cells were performed as follows. Monolayers of Hep 3B or H441 cells were grown in 60 mm dishes with 5 ml of DMEM (10% FBS), and were mock-infected or infected with KDl or KDl-SPB at a multiplicity of infection of 10 plaque forming units (PFU) per cell. Phase contrast photographs of monolayers were taken at 4 and 7 days postinfection (p.i.). Experiments employing western blots of H441 or Hep 3B cells were performed as follows. H441 or Hep 3B cells (in 60 mm dishes) were infected with 10 PFU/cell of KDl or KDl-SPB. At 24 h p.i., the cells were washed three times with PBS and harvested by scraping. The cells were lysed by REPA buffer. The protein concentration was measured by the BIO-RAD DC Protein Assay Kit (BIO-RAD Laboratories, Hercules, CA) and 10 μgof each sample were electrophoresed on 15% sodium dodecylsulfate polyacrylamide gels (SDS- PAGE). The gels were electroblotted onto PVDF membranes (Immobilon, Millipore, Bedford, MA). The membranes were blocked in TBST (50 mM Tπs-Cl, pH 7.6, 150 mM NaCI, 0.2% Tween 20) containing 10% dry milk (Carnation) overnight at 4°C. After blocking, the membranes were incubated with a rabbit polyclonal antiserum agamst E40RF3 (gift of Gary Ketner) or ADP (Tollefson et al., J Virol d<5:3633-3642, 1992), or with M73, a monoclonal antibody against EIA (Harlow et al., J. Virol 55:533-546, 1985). The secondary antibodies were goat anti-rabbit IgG-HRP or goat anti-mouse IgG-HRP. The blots were developed using the ECL protocol (Amersham Pharmacia, Arlington Heights, EL). Expeπments employing a lactate dehydrogenase release assay for cell lysis (Tollefson et al., J Virol 70:2296-2306) were preformed as follows. H441 cells (7.7 x 10 5 cells per 35 mm dish) and Hep 3B cells (9.0 x 10 5 cells per 35 mm dish) were infected at 20 PFU/cell m one ml serum-free DMEM. After an adsorption peπod of 1 h, 3 ml of DMEM (10% FBS) were added (final FBS concentration of 7.5%). Cells were incubated at 37°C with 6% C0 2 . At daily intervals, supernatants were collected, microfuged to remove floating cells, and cell- free supernatants were frozen at -70°C until assayed. Total lysis samples were prepared by addition of 1 OX lysis buffer included m the Cyto Tox 96 kit (Promega, Madison, WI). After all samples were collected, 20 μl samples were assayed in triplicate using the LDH assay kit Cyto Tox 96 and read on an EL340 Microplate reader (BioTecTM Instruments, Inc.) at 490 nm. Expeπments employing immunofluorescence evaluation of H441 and Hep 3B cells were performed as follows. H441 and Hep 3B cells were plated on Corning #1 coverslips in 35 mm dishes. H441 (1.5 x 10 6 cells/35 mm dish) and Hep 3B (9.0 x 10 5 cells/35 mm dish) were infected with 20 PFU/cell of the indicated viruses in 1 ml serum-free DMEM. After 1 h, 1 ml of DMEM/20% FBS was added (final concentration of 10% FBS). At the indicated times (48 h or 6 d p.i.), cells were fixed for 10 mm m 3.7% paraformaldehyde in PBS, then permeabilized for 6 mm in methanol (-20°C) and rehydrated in PBS. Coverslips were stained with rabbit antipeptide antiserum against the Ad E2A-coded DNA binding protem (DBP) (1.400 dilution; gift of Mauπce Green) and mouse monoclonal antibody against fiber (1:400 dilution; gift of Jeff Engler) or were stained with rabbit antiserum to E40RF3 (1:250 dilution; gift of Gary Ketner). Secondary antibodies (Cappel/ICN) were used at 1:50 dilution. All antibodies were diluted m PBS contamιngl% BSA and 0.1% sodium azide. Photographs were taken on a Nikon epifluorescence microscope using a 100X Planapo lens and Tmax 400 film (Kodak). The film was developed m Diafine developer. Analysis of viral DNA replication by Southern hybndization was performed as follows. H441 and Hep 3B cells were grown m 60 mm dishes m DMEM supplemented with 10% FBS. Cells were infected at 70% confluence with 10 PFU/cell of KDl or KDl-SPB. Dishes were incubated in humidified 5% C0 2 atmosphere at 37°C. Total genomic DNAs were isolated at 5, 24, 48, 72, and 96 h p.i. Equal amounts of total genomic DNAs were digested with H dlll and resolved on a 1% agarose gel pπor to transfer onto membranes. A random pnmer 32 P-labeled pBHGlO plasmid probe (Bert et al., Proc. Natl. Acad. Sci. USA 97:8802-8806, 1994) was used for hybndization, and the blots were autoradiographed. DNA fragments were quantitated on a Molecular Dynamics Phosphorlmager. Virus yields were determined as follows. Hep 3B cells or H441 cells grown as monolayers m 35 mm dishes were infected with 10 PFU/cell of KDl or KDl-SPB. At days 0 to 4 (for H441) or days 0 to 9 (for Hep 3B) p.i., cells and culture medium were frozen at - 70°C. Samples were frozen and thawed three times to release the virus from the cells, and total virus yields were determined by plaque assay on A549 monolayers. The effect of KDl-SPB and KDl on H441 and Hep 3B tumors was examined m a nude mouse model (Doronm et al., J Virol 74:6147-6155, 2000). Tumor cells (10 7 cells m 200 μl of DMEM, 50% Matπgel [Becton Dickinson Labware, Bedford, MA] for H441 cells, or 10 7 cells in 200 μl of DMEM plus 10% Matπgel for Hep 3B cells) were injected into flanks of 5-6 weeks old athymic nude mice and allowed to grow for three weeks to about 100 μl (H441) or 150 μl (Hep 3B) volumes. Pre-established tumors (n = 10) were mjected with 50 μl of DMEM or 5 x 10 7 PFU of indicated viruses in DMEM. Injections of the viruses were repeated twice weekly for 3 weeks to the total dose of 3.0 x 10 8 PFU per tumor. Tumor size measurements were taken twice per week for H441 cells, or weekly for Hep 3B cells using a Sylvac digital caliper. Tumor volumes were calculated m accordmg to the formula: length x width 2 12. Data are represented as means of increase in tumor size relative to the tumor size at the initial injection. Results The properties of KDl-SPB m vaπous cell types were compared to those of its "parent", KDl. Figure 25 shows the plaque development properties of these vectors on 293- E4, 293, and A549 cells. The data are plotted as the number of plaques seen on any day of the plaque assay as a percentage of the number of plaques seen at the end of the assay (i.e. when new plaques cease to appear) (Tollefson et al., J. Virol.70:2296-2306, 1966). This assay is an indicator of the size of the plaques. KDl formed plaques equally well on 293-E4 and 293 cells (Figure 25A). With KDl-SPB, plaques were observed about 3-4 days sooner on 293-E4 compared to 293 cells (Fig. 2A). On A549 cells, KDl formed plaques 4-6 days sooner than KDl-SPB (Figure 25B). The properties of KDl-SPB versus KDl were characteπzed in detail in H441 cells, a human papillary lung adenocarcinoma cell line known to express the TTFl transcπption factor and m which the SPB promoter is active (Yan et al., J Biol Chem 270:24852-24857, 1995). Hep 3B cells, a human hepatocellular carcinoma m which the SPB promoter should not be active, were used as a negative control. H441 and Hep 3B monolayers were infected with 10 PFU/cell of KDl or KDl-SPB and photographed at 4 and 7 days p.i. Mock-mfected Hep 3B cells formed a relatively homogeneous monolayer, but H441 cells tended to form structures that resemble syncytia (Figure 26 A, B). As expected, KDl produced cytopathic effect (CPE) on both cell lines at 4 and 7 days p.i (Figure 26A, B) Also as expected, KDl- SPB caused CPE on H441 cells but not on Hep 3B cells. Since CPE m Ad-infected cells is usually an indicator of virus growth, these results suggest that KDl-SPB grows in H441 but not in Hep 3B cells. To examine viral DNA replication, H441 and Hep 3B cells were infected with 10 PFU/cell of KDl or KDl-SPB, then the accumulation of viral DNA was determined by DNA blot. With H441 cells, KDl and KDl-SPB DNAs were readily detected at similar levels at 48-96 h p l. (Figure 27A) With Hep 3B cells, KDl DNA levels were similar to those in H441 cells, but KD 1 -SPB DNA was barely detectable. This was confirmed by Phosphorlmager analysis of the DNA bands (Figure 27B) Growth of KDl-SPB and KDl m H441 and Hep 3B cells was determined by a single step growth assay. Cells were infected with 10 PFU/cell of vector, then total vector yield was determmed by plaque assay Total yield of both vectors was similar m H441 cells, reaching a plateau after 2 days (Fig. 28A). KDl yield plateaued m Hep 3B cells after 2-4 days p.i. (Figure 28B). However, KDl-SPB levels were about 5 logs lower m Hep 3B cells after 2-4 days, and even by 9 days they had not achieved the levels of KDl. We conclude that KDl- SPB grows with significant specificity on H441 versus Hep 3B cells. Further, KDl-SPB grows as well as KDl on H441 cells, indicating that the E4 promoter deletion by itself does not significantly compromise the vector, and that the E4 promoter can be replaced by a tissue- specific promoter m a replication-competent vector. To obtain further details on the replication of KDl-SPB vs KDl in H441 and Hep 3B cells, the expression of representative Ad proteins by KDl-SPB and KDl was examined. H441 or Hep 3B cells were mock-mfected or infected with 10 PFU/ml of KDl or KDl-SPB, then at 24 h p 1. the proteins were extracted and the EIA, E40RF3, and ADP proteins were examined by immunoblot. E40RF3 is one of the six protems coded by the E4 transcπptoon unit (Leppard, J Gen. Virol 75:2131-2138, 1997). As anticipated, KDl-SPB expressed E40RF3 well in H441 cells, but only at trace levels in Hep 3B cells (Figure 29). KDl-SPB expressed the EIA proteins in Hep 3B cells. Synthesis of EIA proteins by KDl-SPB in Hep 3B cells is expected because EIA expression does not require E4 proteins; it also indicates that the block to infection with KDl-SPB is downstream of EIA. KDl expressed EIA m both cell lines, but the amount was less than obtained with KDl-SPB m Hep 3B cells (Figure 29). The increased EIA levels seen with KDl-SPB may reflect its poor ability to enter the late phase of infection (see Discussion). KDl-SPB expressed ADP as well as KDl in H441 cells, but it did not make detectable ADP m Hep 3B cells. ADP is pπmaπly a late protein, so this result is consistent with the relative lack of E4 protein expression, DNA replication, and growth of KDl-SPB m Hep 3B cells. To gain insights into replication events that occur m individual cells, expression of E40RF3, the E2A-DBP, and the fiber late protein was examined by immunofluorescence. H441 or Hep 3B cells were infected with 20 PFU/cell. At 48 h or 6 days p.i., cells were fixed and immunostained. E40RF3 was detected m the nuclei of H441 cells at 48 h p.i. with KDl, KDl-SPB, or dl309 (Figure 30A). (dl309 is an Ad5 mutant that has wild-type EIA, expresses Ad5 levels of ADP, and lacks the E3-RID and E3-14.7K genes). E40RF3 could not be detected in the vast majoπty of Hep 3B cells infected with KDl-SPB (Figure 30A), even at 6 days p.i. (Figure 30B). Thus, KDl-SPB expresses E40RF3 well in H441 but not in Hep 3B cells. Figure 31A shows double label immunofluorescence of DBP and fiber in the same Hep 3B cells at 48 h p.i. with KDl or KDl-SPB. With KDl, there was a strong speckled staining pattern m the nucleus that is typical for DBP at 48 h p.i. (Figure 31 A, top left panel). There was strong staining of fiber throughout these same cells (Figure 31 A, top πght panel). Staining of the cytoplasm and nucleus is expected because fiber is synthesized m the cytoplasm and then transported to the nucleus where viπons assemble. With KDl-SPB at 48 h p.i., about 25% of the cells showed the speckled staining for DBP, and only one cell (7% of total) with the advanced speckled pattern was also stained for fiber (Figure 31 A, bottom two panels). Even at 6 days p 1 , only about 30% of cells showed staining for DBP, and about 20% for fiber (Figure 3 IB) Thus, markedly fewer Hep 3B cells infected with KDl-SPB expressed DBP and especially fiber as compared to KDl . These results indicate that KDl- SPB replicates as well as KDl m H441 cells, no doubt because the SPB promoter is active m H441 cells (Yan et al., J. Biol. Chem. 270:24852-24857, 1995). KDl-SPB barely replicates m Hep 3B cells, presumably because the SPB promoter is minimally active in these cells. At the culmination of replication, Ad-infected cells are lysed and the virus spreads to other cells; this process is mediated in large part by ADP (Tollefson et al., Virology 220:152- 162, 1996; Tollefson et al., J Virol. 70:2296-2306, 1996). To examine vector-induced cell lysis, H441 and Hep 3B cells were mock-infected or infected with 20 PFU/cell of KDl, KDl - SPB, or dl309, and cell lysis was determined by release of lactate dehydrogenase (Tollefson et al., J. Virol. 70:2296-2306, 1996). All vectors lysed H441 cells beginning at 2-3 days p.i. (Figure 32A). KDl and dl309 also lysed Hep 3B cells in the same time period; however, KDl-SPB caused only minimal cell lysis (Figure 9B). Thus, these data, along with the cell spread data in Example 6 and Figure 13, demonstrate that KDl-SPB lyses cells and spreads efficiently from cell-to-cell in H441 but not Hep 3B cells. An experiment was conducted to determine whether KDl-SPB or KDl would suppress H441 tumors in nude mice. H441 cells were injected into each hind flank. When tumors had grown to about 100 μl (H441) or 150 μl (Hep 3B), they were injected twice weekly for 3 weeks with DMEM (mock) or 5 x 10 7 PFU of test virus in 50 μl of DMEM (3.0 x 10 8 total PFU). Ten tumors (5 mice) were used for each virus. Growth of H441 tumors was suppressed similarly by KDl-SPB and KDl (Figure 33 A). KDl suppressed growth of Hep 3B tumors, whereas KDl-SPB caused only minimal suppression (Figure 33B). These results show that KDl-SPB is as effective as KDl in suppressing tumors when the SPB promoter is active. Further, the cell type specificity observed with KDl-SPB in vitro is maintained in vivo. Discussion Tumor specificity is one of the biggest challenges facing cancer gene therapy, i.e. having the therapeutic gene be expressed specifically in cancer cells. Specificity is very important for RC viruses. Two main strategies have been described that in theory confer specificity: transductional targeting and transcriptional targeting. Directing specificity of vectors toward specific cell surface receptors on the target cells has been attempted through various methods. Although this approach is theoretically attractive it might encounter multiple obstacles such as the lack of incorporation of the engineered protein into the virion (Scaria et al., Virology 191:743-753, 1992) or lack of infectivity through the targeted receptor (Cosset et al., J. Virol. 69:6314-6322, 1995). Transcriptional targeting utilizes tumor and tissue specific promoters. In replication-defective vectors these regulatory sequences confine the expression of cytotoxic genes to specific tissues. In replication-competent vectors, as an added layer of regulation, vector replication per se can be placed under the control of tumor or tissue specific promoter/enhancer sequences. In replication-competent Ad, insertion of the tissue or tumor specific promoter/enhancer into the EIA promoter/enhancer region has been used exclusively (Hallenbeck et al., Hum. Gene Ther. 70:1721-1733, 1999; Rodriguez et al., Cancer Res. 57:2559-2563, 1997; Yu et al., Cancer Res. 59, 4200-4203, 1999; Yu et al., Cancer Res. 59:1498-1504, 1999). The rationale behind these vectors is that expression of EIA and therefore the whole Ad transcription program will depend on these tissue or tumor specific promoters. However, as a generic approach, there may be difficulties. The EIA enhancer/promoter is very complex. The enhancer controls not only the EIA promoter but also distant promoters such as the E4 promoter (Shenk, T. pp. 2111-2148 In B.N. Fields, D.M. Knipe, and P.M. Howley (eds.), Fields Virology, Lippmcott-Raven, Philadelphia, 1996). In addition, it has been shown that the EIA enhancer m the inverted terminal repeat region changes tissue specificity of cellular promoters (Shi et al., Hum. Gene Ther. 5:403- 410, 1997). Also, the EIA enhancer/promoter is partially embedded within the signals required to package the Ad genome into vmons, and it may be problematic to remove all the EIA enhancer elements without impainng virus production. Accordmgly, we chose to replace the E4 promoter with a tissue specific promoter. E4 genes are essential for Ad replication, and therefore we expected that the replication of the recombinant virus would be dependent on the tissue specific regulatory elements. To construct KDl-SPB, the ca. 300 bp of the E4 promoter was deleted and the B-500 version (ca. 500 bp) of SPB promoter was inserted (Yan et al., supra) (Figure 24 C, D). We selected the SPB promoter because of its stnct tissue specificity: it is exclusively active m type II alveolar cells and bronchial epithelial cells of the lung (Bohinski et al., 1994, Mol. Cell. Biol 74:5671-5681, 1994). Since the parental virus KDl contains and expresses two EIA mutations that restπct virus replication to tumor cells (Doromn et al., supra), we anticipated that the virus would selectively replicate in cells deπved from lung tumors. Thus, H441 cells, a papillary lung carcinoma cell line, were used to characteπze the replication, gene expression, and functional profile of KDl-SPB. KDl-SPB formed plaques 3-4 days sooner on 293-E4 cells that express E4 proteins than on 293 cells, whereas KDl formed plaques with the same kinetics on both cell lines. These data show that the E4 promoter is active m 293 cells, and that the SPB promoter displays very low activity m 293 cells. It is not clear why KDl-SPB forms plaques on 293 cells; these cells are deπved from human embryonic kidney and at least one of the transcπption factors regulating the SPB promoter (Bohmski et al., supra), hepatocyte nuclear factor 3, is expressed in embryonic kidney. It is also possible that TTFl, the master regulatory factor of SPB expression, is minimally active in 293 cells. KDl grew to equally high titers in H441 and Hep 3B cells (Figure 28A, B). In contrast, KDl-SPB replicated as efficiently as KDl in H441 cells, m which the SPB promoter is active (Yan et al., supra) (Figure 28A), but replicated poorly in Hep 3B cells, most likely because the SPB promoter is inactive (Figure 28B). This selectivity has been confirmed by measuring viral DNA production in the two cell lines. KDl-SPB DNA replication was similar both kinetically and quantitatively to KDl DNA replication m H441, however in Hep 3B cells, KDl-SPB DNA was almost undetectable (Figure 27A, B). The cytopathic effect, a surrogate marker of Ad replication, showed a similar specificity (Figure 26). To further confirm our predictions on the molecular basis of the observed issue specificity we monitored viral protein expression. When cells were infected with KDl-SPB all the viral proteins early or late, except for EIA, were expressed m a tissue-specific fashion (high expression m H441, low to undetectable expression m Hep 3B) (Figures 29-31). We found a good correlation between the levels of E4 promoter activity (E40RF3 expression) and the expression of E2A-DBP, ADP, and fiber proteins. Thus, the SPB promoter retains its tissue specificity in the Ad genome and it seems to be the limiting factor of Ad gene expression m the cell lines tested. As expected, expression of EIA is not tissue-specific. Thus, the regulatory step of tissue-specific Ad DNA replication is downstream of EIA. In Hep 3B cells, KDl-SPB expressed EIA at a higher level than did KDl (Figure 29), strongly suggesting that KDl-SPB replication in most of the Hep3B cells remains at the early stage. The cytolytic effect of KDl-SPB also showed a tissue-specific profile (Figure 32; Figure 13 of Example 6), i.e., preferential lysis of H441 cells over Hep 3B cells, a pattern similar to the specificity observed at the level of DNA replication (Figure 27) and viral protein synthesis (Figures 29-31). This cell type specificity was also observed when these cells were growing as tumors in nude mice. Growth of H441 tumors was suppressed by KDl- SPB and KDl at similar efficacy (Figure 33A). In contrast, KDl-SPB unlike KDl had only mmimal effect on the growth of Hep 3B tumors (Figure 33B). In summary, substitution of the E4 promoter with a tissue specific promoter allows highly tissue specific replication of Ad vectors and m the target tissue it is as efficient as the replication of the parental virus. KDl-SPB lacks all E3 genes except ADP. E3 gpl9K, RED and 14.7K have been shown to protect Ad-mfected cells from attack by cytotoxic lymphocytes and apoptosis-mducmg cytokmes such as tumor necrosis factor and Fas ligand (Wold et al., pp. 200-232 In A.J. Cann (ed.), DNA Virus Replication: Frontiers in Molecular Biology, Oxford University Press, Oxford, 2000; Wold et al., Curr. Opin. Immunol. 11:380- 386, 1999). The therapeutic index (virus produced in H441 cells compared to Hep 3B cells) of KDl-SPB is 10 4 -10 5 for the first 4-5 days (Figure 28). These data compare to data reported by Calydon (10 4 -10 5 ) for their prostate specific viruses (Rodriguez et al., supra; Yu et al., Cancer Res. 59, 4200-4203, 1999; Yu et al., Cancer Res 59:1498-1504, 1999). We suggest that KDl-SPB has some added advantage over vectors reported by other laboratoπes because it encodes a mutant form of EIA that restπcts replication to cancer cells (Doronm et al., supra). Although the lung ranks as the second highest cancer site for both men and women in the U.S. Reis et al., Cancer Res. 55:2398-2424, 2000), lung cancer has not been a major target for cancer vector gene therapy since intratumoral injection of virus is generally not feasible in the lungs. However, there has been a recent report of intratumor injection of a replication- defective Ad vector into a lung tumor, and such an approach could be attempted with KDl- SPB. It may also be feasible to administer KDl-SPB systemically in the lung. In view of the above, it will be seen that the several advantages of the invention are achieved and other advantageous results attained. As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. All references cited in this specification, including patents and patent applications, are hereby incorporated by reference. The discussion of references herein is intended merely to summarize the assertions made by their authors and no admission is made that any reference constitutes prior art. Applicants reserve the right to challenge the accuracy and pertinence of the cited references.

Claims: What is Claimed Is: 1. A recombinant vector which is replication-competent in a neoplastic cell and which overexpresses an adenovirus death protein. 2. The recombinant vector of claim 1 wherein the adenovirus death protein comprises amino acids 1-26, 41-59, and 63-70 of SEQ ED NO:5, SEQ ED NO:6, SEQ ED NO: 7, or SEQ ID NO: 8 or a conservatively substituted variant thereof or wherein the adenovirus death protein comprises SEQ ID NO:5, SEQ ED NO:6, SEQ ED NO:7, or SEQ ED NO:8. 3. The recombinant vector of claim 2 which comprises a recombinant virus. 4. The recombinant vector of claim 3, wherein the recombinant virus is an adenovirus lacking expression of at least one E3 protein selected from the group consisting of: gpl9K; RIDα; RIDβ and 14.7K. 5. The recombinant vector of claim 4 which comprises SEQ ED NO: 3 or SEQ ID NO:4. 6. The recombinant vector of claim 3 which is replication-restricted to neoplastic cells. 7. The recombinant vector of claim 6 which comprises SEQ ID NO: 1 or SEQ ED NO:2. 8. The recombinant vector of claim 3, wherein the recombinant adenovirus comprises a tissue specific promoter, a tumor specific promoter, or an inducible promoter substituted for the E4 promoter. 9. The recombinant vector of claim 8, wherein the tissue-specific promoter is a surfactant protein B promoter. 10. The recombinant vector of claim 6 which comprises SEQ ID NO: 14, SEQ ED NO:15 or SEQ ID NO:16. 11. The recombinant vector of claim 1 , wherein the vector further comprises a gene encoding an anti-cancer product. 12. The recombinant vector of claim 11, wherein the gene encoding an anti- cancer product is in the E3 region of the vector. 13. A method for promoting death of a neoplastic cell comprising contacting the neoplastic cell with at least one vector which is replication competent in the neoplastic cell and which overexpresses an adenovirus death protein. 14. The method of claim 13 wherein the adenovirus death protein comprises amino acids 1-26, 41-59, and 63-70 of SEQ ED NO:5, SEQ ED NO:6, SEQ ID NO:7, or SEQ ID NO: 8 or a conservatively substituted vanant thereof or wherein the adenovirus death protein compnses SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, or SEQ ED NO:8. 15. The method of claim 14, wherein the vector compnses a recombmant adenovirus lacking expression of at least one E3 protein selected from the group consisting of: gpl9K; REDα; RIDβ and 14.7K. 16. The method of claim 15, wherein the neoplastic cell compnses a tumor m a patient and the contacting step compnses admimsteπng the recombinant adenovirus to the tumor. 17. The method of claim 16, further compnsmg the step of passively immunizing the patient against the recombinant adenovirus. 18. The method of claim 17, wherein the recombinant adenovirus compnses SEQ ED NO:3 or SEQ ID NO:4 19. The method of claim 15, wherein the vector is rephcation-restncted to neoplastic cells. 20. The method of claim 19, wherein the vector is a recombmant adenovirus compnsmg SEQ ID NO:l or SEQ ED NO:2. 21. The method of claim 15, wherein the recombinant adenovirus compnses a tissue specific promoter or an inducible promoter substituted for the E4 promoter. 22. The method of claim 21, wherein the tissue specific promoter is a surfactant protein B promoter. 23. The method of claim 22, wherein the recombinant adenovirus compnses SEQ ID NO: 14, SEQ ID NO: 15 or SEQ ED NO: 16. 24. The method of claim 16, further compnsmg treating the tumor with radiation. 25. The method of claim 24, compnsmg admmisteπng more than one recombmant adenovirus to the tumor and treating the tumor with radiation. 26. The method of claim 16, further compnsmg treating the tumor with chemotherapy. 27. The method of claim 26, compnsmg admmisteπng more than one recombmant adenovirus to the tumor and treating the tumor with chemotherapy. 28. The method of claim 16, further compnsmg admmisteπng to the tumor one or more replication-defective adenovirus which expresses an anti-cancer gene product, wherein the recombmant adenovirus complements spread of the replication-defective adenovirus in the tumor. 29. A composition compnsmg: a first recombinant virus which is replication competent in a neoplastic cell and overexpresses an adenovirus death protein; and a second recombinant virus which is replication defective and which expresses an anti-cancer gene product, wherein the first recombinant virus complements replication of the second recombinant virus. 30. The composition of claim 29 wherein the first recombinant virus comprises a recombinant adenovirus lacking expression of at least one E3 protein selected from the group consisting of: gpl9K; REDα; REDβ and 14.7K. 31. The composition of claim 30 wherein the recombinant adenovirus comprises a nucleotide sequence selected from the group consisting of: SEQ ED NO: 1; SEQ ED NO:2; SEQ ED NO:14; SEQ ED NO:15; SEQ ED NO:16; SEQ ID NO:3; or SEQ ED NO:4. 32. A composition comprising a first recombinant virus which is replication-defective in a neoplastic cell and which overexpresses an adenovirus death protein, and a second recombinant virus which is replication-competent in a neoplastic cell.

Inventors: DORONIN KONSTANTIN, TOLLEFSON ANN E, TOTH KAROLY, WOLD WILLIAM S M, DORONIN, KONSTANTIN, TOLLEFSON, ANN, E., TOTH, KAROLY, WOLD, WILLIAM S., M.
Applicants: DORONIN KONSTANTIN, TOLLEFSON ANN E, TOTH KAROLY, UNIV SAINT LOUIS, WOLD WILLIAM S M, DORONIN, KONSTANTIN, SAINT LOUIS UNIVERSITY, TOLLEFSON, ANN, E., TOTH, KAROLY, WOLD, WILLIAM S., M.
Application year: 2000
Main classification: C12N15
IPC codes: A61K31, A61K35, A61K45, A61K48, A61P31, A61P35, A61P43, C07K14, C12N5, C12N7, C12N15