WO2024074825A1

WO2024074825A1 - Adenoviral vector therapy

Info

Publication number: WO2024074825A1
Application number: PCT/GB2023/052561
Authority: WO
Inventors: Alan Parker; Luned BADDER
Original assignee: University College Cardiff Consultants Limited
Priority date: 2022-10-04
Filing date: 2023-10-04
Publication date: 2024-04-11
Also published as: GB202214580D0

Abstract

The invention concerns a modified adenoviral vector of serotype Ad5 comprising a suicide transgene; a pharmaceutical composition comprising same; a combination therapeutic comprising same, the use of said adenoviral vector or pharmaceutical composition or combination therapeutic as a medicament and, in particular to treat cancer; and a method of treating a disease, such as cancer, using said modified adenoviral vector or pharmaceutical composition or combination therapeutic.

Description

0368P/WO As Filed Adenoviral Vector Therapy Field of the Invention The invention concerns a modified adenoviral vector of serotype Ad5 comprising a suicide transgene; a pharmaceutical composition comprising same; a combination therapeutic comprising same, the use of said adenoviral vector or pharmaceutical composition or combination therapeutic as a medicament and, in particular to treat cancer; and a method of treating a disease, such as cancer, using said modified adenoviral vector or pharmaceutical composition or combination therapeutic. Background of the Invention Chemotherapy, radiotherapy, and surgery are still the most efficient approaches to treatment of cancer. However, many tumours demonstrate resistance to these conventional therapies and surgical resection can lead to relapses. Further, the nature of the treatments is often very non-specific and iatrogenic. Consequently, gene therapy is a promising approach to bespoke and targeted cancer treatment. One mode of gene therapy is, so-called, suicide gene therapy, in which cell suicide- inducing transgenes are introduced into cancer cells. It is proposed as an alternative to conventional treatment regimens to reduce the adverse effects observed in these conventional treatments. In suicide gene therapy, typically the therapeutic transgenes convert a non-toxic pro-drug, which penetrates the tumour, into a cytotoxic drug or they express a toxic gene product in the tumour cell. To assist in the targeted delivery to the tumour, the transgenes are administered often using viral or bacterial cells, carrying the suicide-inducing genes, whilst aiming to avoid normal cells, thus providing localised treatment. Viral vectors are generally preferred, with numerous ones having been previously utilised, including those derived from poxviruses, herpes simplex virus, lentivirus, retroviruses, vaccinia virus, adenovirus and adeno-associated viruses. Certain systems have been extensively investigated in the context of suicide gene therapy including the cytosine deaminase/5-fluorocytosine suicide system for cancer therapy. In this therapy, the cytosine deaminase gene (CD), encoded by yeast cytosine deaminase (FCY1) gene and not present in mammalian cells, converts the non-toxic pro-drug 5-Fluorocytosine (5-FC) into the potent and toxic 5-Fluorouracil (5-FU), with 5-FU itself being a routine chemotherapeutic agent. Cellular enzymes then further process the drug to produce three 0368P/WO As Filed cytotoxic anti-metabolites: 1) 5-FdUTP, 2) 5-FUTP and 3) 5-FdUMP, which form various metabolic complexes that result in down regulation of mitochondrial pathways and activation of heat shock proteins, leading to tumour regression. The cytosine deaminase/5-FU system has been improved by also including the gene for uracil phosphoribosyltransferase (UPRT), encoded by the FUR1 gene, which assists in the conversion of 5-FU to 5-FdUMP. The suicide system, as a whole, has been yet further improved through the use of a fusion suicide gene, FCU1, combining both the yeast cytosine deaminase (FCY1) and uracil phosphoribosyltransferase (FUR1) genes. This fusion suicide gene (termed FCU1) encodes a bifunctional chimeric protein that combines the enzymatic activities of both FCY1 and FUR1 and so efficiently catalyzes the direct conversion of 5-FC into the toxic metabolites 5- fluorouracil (5-FU) and 5-fluorouridine-5′monophosphate (5-FUMP), thus bypassing the natural resistance of certain human tumor cells to 5-FU (figure 1). Therefore, the use of the cysteine deaminase cancer therapy, and in particular the FCU1 suicide gene system, offers great promise as a selective cancer gene therapy, and its use has been explored through delivery in adenovirus vectors. However, to date its use has had limited success and its application to patients has not reached any desirable clinical significance. Indeed, as for most current suicide gene therapy strategies, it is still hindered by poor efficiency of in vivo gene transfer, a limited bystander cell killing effect and a need for large prodrug doses. In part, it is thought that this is due to poor tumour therapy transduction and tumour therapy penetration, resulting from poor FCU1 delivery and an insignificant therapeutic (antitumor) effect. Accordingly, there is a need to improve this suicide system in clinical gene therapy, and we herein disclose an adenoviral vector adapted to express FCU1 and designed to overcome the above drawbacks. Statements of the Invention According to a first aspect of the invention there is provided a viral vector of Ad5 serotype adenovirus (herein referred to as Ad5NULL) modified to comprise: a) at least one of I421G, T423N, E424S, E450Q or L426Y point mutation(s) in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) at least one of S408E or P409A point mutation(s) in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); and 0368P/WO As Filed c) at least one of D342E or D342A point mutation(s) in the penton integrin binding motif Arg-Gly-Asp (RGD) wherein said mutation prevents virus binding with α_Vβ₃/α_Vβ₅ integrin; and wherein said vector further comprises or encodes or expresses the FCU1 transgene. Reference herein to FCU1 transgene is reference to the fusion suicide gene that encodes a bifunctional protein that combines the enzymatic activities of both the yeast cytosine deaminase FCY1 and uracil phosphoribosyltransferase FUR1 enzymes and so efficiently catalyzes the conversion of 5-FC into the toxic metabolites 5-fluorouracil (5-FU) and 5- fluorouridine-5′monophosphate (5-FUMP) (figure 1). It is well known in the art and has GenBank accession number AAG33626.1. Reference herein to a vector that comprises or encodes or expresses the FCU1 transgene is reference also to a vector that is adapted to express said transgene, said adaption, typically but not exclusively, being the use of conventional genetic engineering having regard to the vector and host systems. Accordingly, in a preferred embodiment of the invention said FCU1 transgene is effective in the cytosine deaminase/5-fluorocytosine suicide system for cancer therapy and so the vector is for use as a medicament and, in particular, for use in a cytosine deaminase/5-fluorocytosine suicide system, more ideally still, for use in cancer therapy. Indeed, we have found that the viral construct of the invention has surprisingly improved efficacy in said afore system thus providing one or more of the following advantages: improved effectiveness of the toxic 5- Fluorouracil (5-FU) and/or its cytotoxic anti-metabolite 5-FdUMP; use of lower doses of the toxic 5-Fluorouracil (5-FU) and/or its cytotoxic anti-metabolite 5-FdUMP; and the potential for improved metabolic clearance of the toxic 5-Fluorouracil (5-FU) and/or its cytotoxic anti- metabolite 5-FdUMP. We have discovered the Ad5-null vector disclosed herein when comprising or encoding or expressing the FCU1 transgene offers a superior selective gene therapy of surprising efficacy in relation to the cytosine deaminase/5-fluorocytosine suicide system particularly, but not exclusively, for cancer therapy. Specifically, we have discovered when using wildtype Ad5, expressing FCY1 or FCU1, cells were sensitised to the prodrug 5-FC, with FCU1 better than FCY1, as expected. Cells lacking the binding receptor CAR were not sensitised. Similarly, when using Ad5NULL, expressing FCY1 or FCU1, cells were sensitised to the prodrug 5-FC, with FCU1 better than FCY1, as expected. Cells lacking the binding receptor αvβ6 were not 0368P/WO As Filed sensitised. However, when comparing the effective activity, measured by the indicator IC_50, for these two different vectors, the use of the transgene FCY1 or FCU1 was more effective in Ad5_NULL. However, we in fact, observed an IC₅₀ approximately 10.8 and 26.2 times lower in cells transduced with Ad5NULL-A20-FCU1 versus Ad5-FCU1 (Table 2). This was an efficacy of unexpected but favourable magnitude. Given that CFPAC1 and BxPC3 cells had similar receptor expression levels of CAR and αvβ6 integrin, this suggests that the use of the Ad5NULL- A20- vector in combination with the transgene FCU1 results in a lower IC₅₀ and thus a much greater sensitivity to 5-FC compared to Ad5 WT. This suggests that Ad5NULL-A20-FCU1 is able to selectively infect cells in a αvβ6 integrin dependent manner, resulting in a superior and increased sensitisation to 5-FC, particularly but not exclusively in pancreatic tumour cells with high expression levels of αvβ6 integrin. Indeed, when comparing the effective activity IC50 for these vectors in cell lines expressing similar levels of both CAR (the entry receptor for Ad5) and αvβ6 integrin (the entry receptor for Ad5NULL-A20), FCU1 was substantially, and unexpectedly, better in Ad5NULL-A20 than Ad5 (Table 2), whereas FCY1 was similarly effective in Ad5 and Ad5NULL-A20 (Table 1). For example, there was an increase in activity, or sensitivity, of on average 10-fold for FCU1 versus FCY1 in Ad5 in CFPAC1 at 5000 vp/cell dose, and an average 20 fold for FCU1 versus FCY1 in Ad5 in BXPC3 at 5000 vp/cell dose (as expected because of the known greater potency of FCU1 compared to FCY1) Table 3 rows 1 & 2, whereas for Ad5NULL-A20, there was an average 95-fold increase for FCU1 versus FCY1 in CFPAC1 at 5000 vp/cell dose and a 200 fold increase in BXPC3 at 5000 vp/cell dose Table 3 rows 1 & 2. This would suggest the Ad5NULL-A20-FCU1 vector is ~10 times better than the Ad5-FCU1 vector, demonstrating an unexpected synergy between vector and transgene in Ad5NULL-A20 and FCU1. Reference herein to sensitisation, sensitivity and sensitized, including other derivatives of the term sensitive, includes reference to the toxic compound 5-Fluorouracil (5-FU) having a greater effect than it would have done without the intervention described herein or use of the claimed vector. Amongst the viruses exploited for therapeutic application, Human Adenoviruses (HAdV) have important clinical applications ranging from vectors for gene therapy and vaccines to oncolytic viruses. A number of oncolytic HAdV virotherapies have entered clinical trials and have shown safety and feasibility, although delivery and efficacy require optimization before oncolytic adenovirus can be used as an effective cancer therapy. Adenovirus 5 (Ad5) is a common vector deployed in numerous clinical trials for cancer and gene therapies (clinicaltrials.gov, 2016) because it can be genetically manipulated, and it tolerates large transgenes. However, 0368P/WO As Filed Ad5 has a natural tropism that leads to widespread distribution of the vector in normal healthy tissues. Entry of group C adenoviruses, such as Ad5, into cells is thought to involve high affinity binding of the virus to the cell through interaction of the viral fiber protein with coxsackievirus–adenovirus receptor (CAR). Therefore, for the purpose of anti-cancer therapy, targeting of adenoviral vectors to specific tissues or cell types requires modification of the normal tropism of the vector to improve specificity. We have previously reported (WO2019158914) that the Ad5 adenovirus, when modified to comprise mutations a)-c) above, ablated the native tropisms of Ad5 by mutating the main capsid proteins: hexon, fiber and penton. A triple de-targeted Ad5-based vector backbone was generated, with modifications in the hexon hypervariable region 7 (HVR7 mutation), fiber knob AB loop (KO1 mutation) and penton integrin-binding motif Arg-Gly-Asp (RGD mutation) with substitution mutations in amino acid residues responsible for binding to coagulation factor 10 (FX), coxsackie and adenovirus receptor (CAR), and αvβ3/5 integrins, respectively. This modified virus has reduced ability to infect off-target tissues, indeed, it is prevented/inhibited from infecting liver and spleen and also its ability to infect cells of the body in a widespread manner is also compromised. Thus, the modified adenovirus is compromised in terms of the tissue it can infect. Said modified Ad5 vector is described in detail in patent application WO2019158914. The term Ad5.3D is used in said patent disclosure but is referenced herein as Ad5NULL. Any sequence of Ad5 that is known in the art can be the vector according to the invention when comprising the three modifications a) – c) disclosed herein. In a preferred embodiment, the Ad5 serotype that is modified as disclosed herein comprises the accession number AC_000008.1. As is known in the art, the hexon protein is highly conserved among the different adenovirus serotypes, with the exception of nine hypervariable regions (HVRs). These HVRs reside in two distinct loops that form the exposed surface of the hexon protein, HVRs 1–6 lie within the DE1 loop and HVRs 7–9 are located within the FG1 loop. Accordingly, reference herein to at least one mutation in HVR7 refers to a mutation in the hypervariable region 7. Specifically, said at least one HVR7 mutation prevents interaction with coagulation Factor X thereby limiting off-target sequestration of the modified adenovirus to the liver, and improved targeting to target cancer cells. In a preferred embodiment, said at least one HVR7 mutation comprises at least one amino substitution mutation to prevent FX interaction selected from one or more of the group comprising: I421G, T423N, E424S, E450Q and L426Y. Most preferably, said at least one HVR7 mutation comprises additionally or alternatively at least one of I421G, T423N, E424S, and L426Y point mutations. 0368P/WO As Filed Adenoviral infection commences with recognition of host cell receptors by means of specialised proteins on the viral surface i.e., the adenovirus fiber protein and in particular the globular carboxy-terminal domain of the adenovirus fiber protein, termed the carboxy-terminal knob domain. Accordingly, reference herein to a knob of an adenoviral fiber protein is reference to the globular carboxy-terminal domain of the adenovirus fiber protein. Accordingly, reference to at least one KO1 mutation refers to at least one mutation in the fiber knob region AB loop. Specifically, said at least one KO1 mutation prevents virus binding to CAR. In a preferred embodiment, said at least one KO1 mutation comprises at least one point mutation to prevent CAR binding selected from one or more of the group comprising: S408E and P409A. Most preferably said point mutation comprises both S408E and P409A point mutations. Adenovirus penton base contains five Arg-Gly-Asp sequences and bind integrins alpha v beta 3 and alpha v beta 5 (αVβ3/αVβ5) to promote viral infection by permitting virus internalization. Through prevention of this interaction, we have found that off-site targeting to the spleen is reduced, thereby promoting tumour specific targeting and, moreover, there is a dampening release of pro-inflammatory cytokines that otherwise lead to adverse immune host responses when used in the context of anti-cancer therapy. Accordingly, reference to at least one RGD mutation refers to at least one mutation in the penton integrin binding motif Arg-Gly-Asp (RGD mutation) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin. In a preferred embodiment, said at least one RGD mutation comprises at least one point mutation selected from the group comprising: D342E and D342A, to produce RGE or RGA, respectively. Most preferably said point mutation is D342E to produce RGE. In yet a further preferred embodiment of the invention said viral vector is further modified to include at least target cell targeting modification that selectively targets specific host cells, in particular, specific types of cancer cells. Examples of cell targeting modifications/sequences are known to those in the art such as, but not limited to, NGR (containing) peptides to bind aminopeptidase N. in particular the viral vector is modified to present at least one NGR in the HI loop of the adenoviral fiber protein. Additionally, or alternatively, the viral vector is further modified to include at least one YSA (containing) peptide to bind to pan-cancer marker EphA2, preferably the viral vector presents at least one YSA peptide in the chimeric fiber protein, resulting in strong transduction of EphA2-positive but not EphA2-negative cancer cells. In a further preferred embodiment of the invention said viral vector is further modified to include at least one growth factor antibodies. Preferably the growth factor antibody is linked to the 0368P/WO As Filed vector using a chemical linkage and then the antibody is used as a targeting moiety, e.g., bFGF, EGFR, antibodies (e.g., Cetuximab, Herceptin, Avastin or the like). The chemical linkage may comprise the use of an avidin/biotin linkage. In a yet further preferred embodiment of the invention said viral vector is further modified to include at least one matrix degrading enzyme. Ideally, the one or more of such enzymes are attached (typically, chemically linked e.g., linkage via hyaluronidase) to the outside of the virus, in this way, the matrix degrading enzyme can degrade extracellular matrix and so enable the virus to permeate into the tumour microenvironment more efficiently. In a yet further still preferred embodiment of the invention the viral vector is modified to present or express a cancer cell targeting peptide, such as an αvβ6 integrin binding peptide (typically this peptide is identified using conventional techniques, such as sequence binding and homology techniques) for example the A20 peptide sequence NAVPNLRGDLQVLAQKVART (SEQ ID NO: 1) may be used and the modification is undertaken so that the cell targeting peptide is presented or expressed in the viral fiber knob HI loop (this particular modified virus hereinafter is referred to as Ad5NULL-A20). A20 was originally derived from foot-and-mouth disease virus (FMDV) capsid protein VP1 and has a natively high affinity to αvβ6 integrin. αvβ6 integrin is expressed in a third of ovarian cancers and in a variety of other epithelial cancers and is non-detectable in healthy adult tissues. Therefore, as will be appreciated by those skilled in the art, through presentation or expression of this A20 sequence in the viral vector, one can selectively target αvβ6 integrin expressing or overexpressing cancers such as, but not limited to, ovarian cancer, pancreatic cancer, oesophageal cancer, lung cancer, cervical cancer, head and neck cancer, oral cancer, cancer of the larynx, skin cancer, breast cancer, kidney cancer, and colorectal cancer. The skilled person will appreciate that homologues, orthologues, or functional derivatives of the recited modified viral vector mutations will also find use in the context of the present invention. Thus, for instance mutations which include one or more additions, deletions, substitutions or the like are encompassed by the present invention. In addition, it may be possible to replace one amino acid with another of similar “type”. For instance, replacing one hydrophobic amino acid with another one can be achieved by using a program such as the CLUSTAL program to compare amino acid sequences. This program compares amino acid sequences and finds the optimal alignment by inserting spaces in either sequence as appropriate. It is possible to calculate amino acid identity or similarity (identity means conservation of amino acid type) for an optimal alignment. A program like BLASTx will align 0368P/WO As Filed the longest stretch of similar sequences and assign a value to the fit. It is thus possible to obtain a comparison where several regions of similarity are found, each having a different score. Both types of analysis are contemplated in the present invention. In yet a further preferred embodiment still, there is provided a viral vector of Ad5 serotype adenovirus (Ad5_NULL-A20) modified to comprise: a) at least one of I421G, T423N, E424S, E450Q or L426Y point mutation(s) in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) at least one of S408E or P409A point mutation(s) in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); c) at least one of D342E or D342A point mutation(s) in the penton integrin binding motif Arg-Gly-Asp (RGD) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin; and d) presentation or expression of the A20 peptide sequence NAVPNLRGDLQVLAQKVART (SEQ ID NO:1) in the viral fiber knob HI loop; and wherein said modified vector further comprises or encodes or expresses the FCU1 transgene. More preferably still said a viral vector (Ad5NULL-A20) comprises: a) I421G, T423N, E424S, and L426Y point mutations in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) S408E and P409A point mutations in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); c) D342E point mutation in the penton integrin binding motif Arg-Gly-Asp (to produce RGE mutation) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin; and d) insertion or expression of the A20 peptide sequence NAVPNLRGDLQVLAQKVART (SEQ ID NO:1) in the viral fiber knob HI loop; and wherein said vector further comprises or encodes or expresses the FCU1 transgene. In yet a further preferred embodiment still, said vector is further modified to include and express at least one further transgene encoding a molecule or agent such as, but not limited 0368P/WO As Filed to, a therapeutic agent, in addition to that encoded by FCU1. This embodiment therefore concerns the delivery of an additional agent, intracellularly, to exert an additional or further therapeutic action on the targeted cell. According to a second aspect of the invention there is provided the vector as defined herein for use as a medicament. According to a third aspect of the invention there is provided the vector as defined herein for use in the treatment of cancer or other diseases where αvβ6 expression can be pathological, such as but not limited to fibrosis, aberrant wound healing such as chronic wounds, and epidermolysis bullosa. According to a fourth aspect of the invention there is provided the vector as defined herein for use in the manufacture of a medicament to treat cancer or other diseases where αvβ6 expression can be pathological, such as but not limited to fibrosis, aberrant wound healing such as chronic wounds, and epidermolysis bullosa. Most preferably the cancer referred to herein includes any one or more of the following cancers: nasopharyngeal cancer, synovial cancer, hepatocellular cancer, renal cancer, cancer of connective tissues, melanoma, lung cancer, bowel cancer, colon cancer, rectal cancer, colorectal cancer, brain cancer, throat cancer, oral cancer, liver cancer, bone cancer, pancreatic cancer, choriocarcinoma, gastrinoma, pheochromocytoma, prolactinoma, T-cell leukemia/lymphoma, neuroma, von Hippel-Lindau disease, Zollinger-Ellison syndrome, adrenal cancer, anal cancer, bile duct cancer, bladder cancer, ureter cancer, oligodendroglioma, neuroblastoma, meningioma, spinal cord tumor, osteochondroma, chondrosarcoma, Ewing's sarcoma, cancer of unknown primary site, carcinoid, carcinoid of gastrointestinal tract, fibrosarcoma, breast cancer, Paget's disease, cervical cancer, colorectal cancer, rectal cancer, esophagus cancer, gall bladder cancer, head cancer, eye cancer, neck cancer, kidney cancer, Wilms' tumor, Kaposi's sarcoma, prostate cancer, testicular cancer, Hodgkin's disease, non-Hodgkin's lymphoma, skin cancer, mesothelioma, multiple myeloma, ovarian cancer, endocrine pancreatic cancer, glucagonoma, parathyroid cancer, penis cancer, pituitary cancer, soft tissue sarcoma, retinoblastoma, small intestine cancer, stomach cancer, thymus cancer, thyroid cancer, trophoblastic cancer, hydatidiform mole, uterine cancer, endometrial cancer, vagina cancer, vulva cancer, acoustic neuroma, mycosis fungoides, insulinoma, carcinoid syndrome, somatostatinoma, gum cancer, heart cancer, lip cancer, meninges cancer, mouth cancer, nerve cancer, palate cancer, parotid gland cancer, 0368P/WO As Filed peritoneum cancer, pharynx cancer, pleural cancer, salivary gland cancer, tongue cancer and tonsil cancer. Compounds for use in medicine will generally be provided in a pharmaceutical or veterinary composition and therefore according to a yet fifth aspect of the invention there is provided a pharmaceutical composition comprising the vector as defined herein and a pharmaceutically acceptable carrier, adjuvant, diluent or excipient. Suitable pharmaceutical excipients are well known to those of skill in the art. Pharmaceutical compositions may be formulated for administration by any suitable route, for example oral, buccal, nasal or bronchial (inhaled), transdermal or parenteral and may be prepared by any method well known in the art of pharmacy. The composition may be prepared by bringing into association the above defined vector with the carrier. In general, the formulations are prepared by uniformly and intimately bringing into association the adenovirus with liquid carriers or finely divided solid carriers or both, and then if necessary, shaping the product. The invention extends to methods for preparing a pharmaceutical composition comprising bringing a vector as defined above in conjunction or association with a pharmaceutically or veterinary acceptable carrier or vehicle. According to a further aspect of the invention there is provided a combination therapeutic comprising the modified adenoviral vector described herein and at least one further therapeutic agent, including the pro-drug 5-Fluorocytosine (5-FC). It is clear that the above viral vector and its use, works when the suicide transgene encoded by the viral vector is administered with its corresponding non-toxic pro-drug. Preferred clinical methods and uses of the corresponding non-toxic pro-drug will vary but they are all contemplated within the scope of the invention. It is preferred if the suicide transgene is FCU- 1 and the non-toxic pro-drug is 5-FC. According to an even further aspect of the invention, there is provided a method for treating cancer or fibrosis, aberrant wound healing or chronic wounds, and epidermolysis bullosa comprising: administering an effective amount of the viral vector or pharmaceutical composition or combination therapeutic as defined herein to a patient in need thereof. 0368P/WO As Filed Reference herein to an "effective amount" of the adenovirus or a composition comprising same is one that is sufficient to achieve a desired biological effect, such as cancer cell death. It is understood that the effective dosage will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. Typically, the effective amount is determined by those administering the treatment. In a preferred method, the viral vector according to the invention may be administered to a subject by any suitable route. Preferably this is direct intra-tumoral injection when treating malignant solid tumours, including through the use of imaging guidance to target the tumour or tumours. Intra-tumoral injection includes direct injection into superficial skin, subcutaneous or nodal tumours, and imaging guided (including CT, MRI or ultrasound) injection into deeper or harder to localize deposits including in visceral organs and elsewhere. In another preferred embodiment, the adenoviral vector is injected into a blood vessel, preferably a blood vessel supplying a tumour. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprises”, or variations such as “comprises” or “comprising” is used in an inclusive sense i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. All references, including any patent or patent application, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. Further, no admission is made that any of the prior art constitutes part of the common general knowledge in the art. Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the present invention will become apparent from the following examples. Generally speaking, the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including the accompanying claims and drawings). Thus, features, integers, characteristics, compounds or chemical moieties described in conjunction with a particular aspect, embodiment or example of the invention are to be 0368P/WO As Filed understood to be applicable to any other aspect, embodiment or example described herein, unless incompatible therewith. Moreover, unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. An embodiment of the present invention will now be described by way of example only with reference to the following wherein: Figure 1. FCY1 and FCU1 transgene sensitise cells to a non-toxic prodrug (A.) Schematic representation of FCY1 and FCU1 transgenes incorporated within Ad5 and Ad5NULL-A20 vectors, and downstream effects following transgene delivery in vitro. Replication-deficient Ad5 (which infects via ubiquitous CAR receptor) and Ad5NULL-A20 (which infect cells via αvβ6 integrin) vectors expressing cytosine deaminase (FCY1, CD) catalyses the conversion of a relatively nontoxic antifungal agent, 5-fluorocytosine (5-FC), into the toxic metabolites 5-fluorouracil (5-FU). Vectors expressing a bifunctional chimeric protein, FCU1, that combines enzymatic activities of both cytosine deaminase and uracil phosphoribosyltransferase genes (UPRTase) to efficiently catalyse the direct conversion of 5- FC into the toxic metabolites 5-FU and 5-fluorouridine monophosphate (5-FUMP). The accumulation of toxic metabolites in vitro lead to cell death. (B.) Flow cytometry profiling of surface expression of αvβ6 and CAR in a panel of pancreatic cell lines. Cells were gated to exclude dead cells, with a minimum of 10 000 events recorded per cell line. Median Fluorescence Intensity (MFI) values were calculated per cell population and overall percentage of CAR or αvβ6- positive cells from the total population of gated cells. Figure 2. Ad5 Cytosine deaminase virotherapies sensitize CAR+ cells to 5-FC in vitro but do not sensitize cells lacking CAR expression (A.) Ad5-FCY1 and Ad5-FCU1, which infect via ubiquitous CAR receptor, sensitises CAR+ PT45 pancreatic tumour cells to 5-FC treatment. Dose-response survival curves of PT45 (CAR+) cells exposed to 5-FC for 3 days following infection with 500, 1000 and 5000 vp/cell Ad5-FCY1, Ad5-FCU1, or a replication-deficient Ad5 control vector. Cell viability was 0368P/WO As Filed estimated by Cell-Titer Glo cell viability assay. Data are represented as mean ± SEM, n = 3. Two-way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. (B.) Ad5-FCY1 and Ad5-FCU1, which infect via ubiquitous CAR receptor, do not enhance sensitization of CAR- CHO-K1 cells to 5-FC treatment. Dose-response survival curves of CHO-K1 (CAR-) cells exposed to 5-FC for 3 days following infection with 500, 1000 and 5000 vp/cell Ad5-FCY1, Ad5-FCU1, or a replication- deficient Ad5 control vector. Cell viability was estimated by Cell-Titer Glo cell viability assay. Data are represented as mean ± SEM, n = 3. Two-way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. Figure 3. Ad5 Cytosine deaminase virotherapies sensitize PDAC cells lines to 5-FC High CAR expression levels correlate with increased sensitivity to Ad5-FCU1 and 5-FC treatment. Dose-response survival curves of multiple pancreatic cell lines treated with 5-FC following infection with 5000 vp/cell Ad5-FCY1 (A.) and Ad5-FCU1 (B.). Cell viability was estimated by Cell-Titer Glo. Data are represented as mean ± SEM. (C.) Pancreatic cell line response (IC50) to a dose range of 5-FC following infection with 500 – 5000 vp/cell of Ad5- FCU1 as quantified by CellTiter Glo. Cells were treated with 5-FC for 3 days following 24 hour infection with Ad5-FCU1. Dots represent IC50 estimates from biological repeats. Mean effects are shown and error bars represent S.E.M. Figure 4. Ad5NULL-A20 Cytosine deaminase virotherapies sensitize αvβ6 cells to 5-FC in vitro but do not sensitize cells lacking αvβ6 expression (A.) Ad5NULL-A20 -FCY1 and Ad5NULL-A20 -FCU1, which infect via αvβ6 integrin, sensitises αvβ6+ CFPAC1 pancreatic cell line to 5-FC treatment. Dose-response survival curves of CFPAC1 (αvβ6+) cells exposed to 5-FC for 3 days following infection with 500, 1000 and 5000 vp/cell Ad5NULL-A20 -FCY1, Ad5NULL-A20 -FCU1, or a replication-deficient , Ad5NULL-A20 control vector. Cell viability was estimated by Cell-Titer Glo cell viability assay. Data are represented as mean ± SEM, n = 3. Two-way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. (B.) Ad5NULL-A20 -FCY1 and Ad5NULL-A20 -FCU1, which infect via αvβ6 integrin, do not enhance sensitization of PT45(αvβ6-) cells to 5-FC treatment. Dose-response survival curves of PT45(αvβ6-) cells exposed to 5-FC for 3 days following infection with 500, 1000 and 5000 vp/cell Ad5_NULL-A20 - FCY1, Ad5NULL-A20 -FCU1, or a replication-deficient , Ad5NULL-A20 control vector. Cell viability was estimated by Cell-Titer Glo cell viability assay. Data are represented as mean ± SEM, n = 3. Two-way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. 0368P/WO As Filed Figure 5. Ad5_NULL-A20 Cytosine deaminase virotherapies sensitize αvβ6 PDAC cells lines to 5-FC High αvβ6 integrin expression levels correlate with increased sensitivity to Ad5_NULL-A20-FCU1 and 5-FC treatment. Dose-response survival curves of multiple pancreatic cell lines treated with 5-FC following infection with 5000 vp/cell Ad5_NULL-A20-FCY1 (A.) and Ad5_NULL-A20-FCU1 (B.). Cell viability was estimated by Cell-Titer Glo. Data are represented as mean ± SEM, n = 3. C. Pancreatic cell line response (IC₅₀) to a dose range of 5-FC following infection with 500 – 5000 vp/cell of Ad5_NULL-A20-FCU1 as quantified by CellTiter Glo. Cells were treated with 5- FC for 3 days following 24 hour infection with Ad5NULL-A20-FCU1. Dots represent IC50 estimates from biological repeats. Mean effects are shown and error bars represent S.E.M from n=3 biological repeats. Figure 6. Schematic of translation ex vivo organoid models Schematic representation of the generation of mouse pancreatic organoids containing Kras and Tp53 mutations as a representative model of pancreatic cancer. KRAS^LSL-G12D/+; Trp53^LSL- ^R172H/+; Pdx1-Cre(KPC) were crossed with ROSA26^LSL-RFP mice to label pancreatic epithelial cells expressing Cre. Once tumour formation occurred, pancreatic tissue was dissected and digested to extract tumour cells. Cell fragments plated in Matrigel and overlaid in organoid media formed three-dimensional (3D) pancreatic organoid structures in culture. Figure 7. Schematic of treatment in ex vivo organoid models (A.) Representative αvβ6 integrin immunohistochemistry from KPC mouse ductal structures and αvβ6 integrin screening of mouse organoids by flow cytometry show that αvβ6 integrin expression is retained in Panc01MO organoid cultures. (B.) Schematic of organoid generation and infection with Ad5NULL-A20-FCU1 or Ad5-GFP. Figure 8. Ad5NULL-A20-FCU1 sensitize αvβ6 integrin expressing organoids to 5-FC, and they exhibit impaired viability following 5-FC treatment KPC-derived organoids (Panc01MO) are sensitised to 5-FC treatment following infection with Ad5NULL-A20-FCU1. Representative images of Panc01MO organoids following 5 days of treatment with 5-FC following mock, Ad5-GFP, and Ad5_NULL-A20-FCU1 infections. Scale bar = 100 µm. Organoids were infected with 5000 vp/cell of virus for 24 hours prior to treatment with a range of 5-FC doses. Cell viability was estimated by Cell-Titer Glo, with IC50 values of 0.01 mM in Ad5_NULL-A20-FCU1-infected organoids . Data are represented as mean ± SEM, n = 3. Two-way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. 0368P/WO As Filed Figure 9. Ad5_NULL-A20 –FCU1 infection impairs growth in Panc01MO organoids treated with 5-FC (A.) Representative images of Panc01MO organoids infected with Ad5-GFP control virus and Ad5_NULL-A20-FCU1 for 24 hours prior to treatment with 5-FC. Images show time lapse captures of the same well from 12 hour- 120 hour post drug treatment (5-FC, 10 mM) and show organoid growth in no virus- and Ad5-GFP- conditions and limited organoids formation in Ad5_NULL-A20- FCU1- treated structures. (B.) Incucyte generated organoid area plots from Panc01MO organoids treated with 5-FC alone, or following infection with Ad5NULL-A20-FCU1 or Ad5-GFP. Data are presented as average organoid area (µm²) ±SD from 0 to 120 hours after 5-FC treatment. Figure 10. Patient-derived PDAC organoids show sensitisation to Ad5NULL-A20-FCU1 and 5-FC combination treatment (A.) αvβ6 Integrin and CAR screening of patient-derived PDAC organoids (PDM38, PDM39) by flow cytometry. (B.) Ad5NULL-A20-FCU1 sensitise patient-derived pancreatic tumour organoids to 5-FC treatment., PDM-38 and PDM-39 organoids were infected as fragments with 5000 vp/cell of virus for 24 hours prior to treatment with a range of 5-FC doses. Cell viability was estimated by Cell-Titer Glo. Data are represented as mean ± SEM, n = 3. Two- way ANOVA with Tukey’s post hoc test was used to calculate p values; * p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. Figure 11. Ad5-FCU1 and Ad5NULL-A20-FCU1 mediated bystander effects (A). Naïve CFPAC1 cells are sensitised to 5-FC by transduction of neighbouring cell populations. CFPAC1 cells were transduced with 1000 vp/cell of virus prior to seeding in a mixed population with naïve cells.0 mM, 1 mM and 10 mM of 5-FC were then added to cells for 3 days. Cell viability measurements were estimated by Cell Titer Glo and normalised to non-treated controls. Data are represented as mean ± SEM, n = 3. (B.) Naïve CFPAC1 cells were treated with supernatants harvested from CFPAC1 cells transduced with 1000 vp/cell of virus and treated with 5-FC. Viability was assessed following 3 days in culture. Data are represented as mean ± SEM, n = 3. Table 1. IC50 values (mM) of pancreatic cells transduced with Ad5-FCY1 and Ad5NULL-A20- FCY1 at 500 vp/cell, 1000vp/cell and 5000 vp/cell. 0368P/WO As Filed Table 2. IC₅₀ values (mM) of pancreatic cells transduced with Ad5-FCU1 and Ad5_NULL-A20- FCU1 at 500 vp/cell, 1000vp/cell and 5000 vp/cell. Table 3. Comparison of IC₅₀ values (mM) of pancreatic cells transduced with Ad5-FCY1 versus Ad5-FCU1 and Ad5_NULL-A20-FCY1 versus Ad5_NULL-A20-FCU1 at 500 vp/cell, 1000vp/cell and 5000 vp/cell and exposed to 5-FC. MATERIALS AND METHODS Viral vector generation Adenovirus vectors were generated using genetic modifications by AdZ homologous recombineering using previously described methods (Uusi-Kerttula., et al 2018). Replication- deficient vectors based on a wild type Ad5 genome were modified to generate the Ad5NULL- A20 platform. Ablation of CAR binding was achieved via the KO1 mutation in the AB loop of the L5 fiber knob gene; ablation of binding to coagulation factor 10 via a mutation in hypervariable region 7 of the L3 hexon gene; ablation of αvβ3/5 integrin binding via RGD-RGE mutation in the L2 penton base gene. Retargeting of the modified Ad genome to αvβ6 integrin was achieved by insertion of A20 peptide sequence from FMDV (NAVPNLRGDLQVKVART) into the viral fiber knob HI loop (between residues G546 and D547). Gene synthesised FCY1 and FCU1 (codon optimised) PCR fragments were inserted into sacB cassette under the control of a CMV promoter. Viruses were produced in either T-REx-293 (Ad5) or HEK293-β6 cells (A20-modified) cell lines. DNA was amplified using a maxiprep kit as per the manufacturers guidelines. Virus particles were generated by lipofectamine transfection in a T25 CELLBIND flask of T-rex of 293B6 cells. When cytopathic effect (CPE) was observed in cells, cells were collected and virus was further amplified in expanded cells. Caesium chloride (CsCl) two-step purification method was used to extract purified virus. Viral particles/mL were quantified using a microBCA kit. Cell lines and culture Human pancreatic cancer cells, CFPAC1, Panc10.05, PT45, (American Type Culture Collection (ATCC)) were maintained in Dulbecco’s modified Eagle’s medium (DMEM) (Sigma- Aldrich) supplemented with 10% heat-inactivated foetal bovine serum (FBS), 1% penicillin/streptomycin(P/S), 1% L-glutamine. MiaPaCa2, ASPC1, BxPC3 (ATCC) cells were maintained in Roswell Park Memorial Institute (RPMI) 1640 Medium supplemented with 10% 0368P/WO As Filed FBS, 1% P/S, 1% L-glutamine. All cultures were maintained in a 5% CO2 humidified atmosphere at 37ºC. All cell lines were routinely tested for mycoplasma using MycoAlert Mycoplasma detection kit (Lonza). Cell viability assay Cells were seeded at a density of 5000 cells per well in triplicate in white clear-bottomed 96 well plates. Following 24 hours in culture, cells were infected with indicated viruses, within a range of 500 – 5000 viral particles (vp) per cell. Viruses were diluted in serum-free growth medium, and cells were infected for 24 hours at 37ºC. Cells were then washed with PBS and incubated in full growth medium containing a dilution of 5-FC (Sigma) or PBS vehicle control for 3 days. Cell viability was measured using CellTiter-Glo® Luminescent Cell Viability Assay (Promega) as per the manufacturer’s instructions, and luminescence was measured with a multimode plate reader (BioTek). Relative luminescence units were normalised to the vehicle control, with FCU1- and FCY1- viruses normalised to virus controls. Mouse pancreatic organoids KRAS^LSL-G12D/+; Trp53^LSL-R172H/+; Pdx1-Cre(KPC) were crossed with ROSA26^LSL-RFP mice to label pancreatic epithelial cells expressing Cre as described previously (Hill et al ., 2021). Animals were housed in conventional pathogen-free animal facilities and all procedures were conducted in accordance with the UK Home Office regulations under the guidelines of Cardiff University Animal Welfare and Ethics Committee. Isolation of transformed mouse pancreatic cells for the generation of organoids were performed as previously described. At specified time points the pancreas was harvested and routinely dissected for downstream analyses or organoid culture. For generation of organoids, mouse pancreas was mechanically dissociated before digestion in collagenase Type 1 and Dispase II to a concentration of 0.125mg/mL at 37°C. Following several washes in HBSS supplemented with 5% FBS, tissue was passed through a 40 μm cell strainer. The washed cells were then resuspended in Matrigel (Corning) and seeded within individual domes in 24 well plates. Once polymerised, pancreatic cells were overlaid with expansion medium (Advanced DMEM F12, B27 (ThermoFisher), N2, 1.25 mM n-acetyl-L-cysteine, 5% R-spondin conditioned medium, 10 mM Nicotinamide, 10 nM recombinant human [Leu15] Gastrin I, 50 ng/mL recombinant mouse EGF, 100 ng/mL recombinant human FGF10 and 25 ng/mL recombinant human Noggin and incubated under standard tissue culture conditions (37°C, 5% CO2). Immunohistochemical staining 0368P/WO As Filed Tumour sections from mouse pancreatic tissue were mounted on slides prior to serial washes in xylene and graded ethanol (100%, 90% and 70%). Protease antigen retrieval was carried out by adding protease 2 (0.1 mg/ mL, Roche) to sections and at 37 °C for 12 minutes. Slides were washed and incubated with 1% H₂O₂ for 15 minutes at room temperature, washed, and blocked using 2.5% horse serum for 30 minutes at room temperature. αvβ6 integrin primary antibody was added to slides (1:750 ; EM05201, Absolute Antibody) in 1% BSA/PBS at 4°C overnight. Primary antibody was removed and replaced with diluted ImmPACT DAB chromogen (Vector Labs) for 4 minutes at room temperature. Slides were submerged in Mayer’s haematoxylin prior to rinsing in ddH2O. DPX mountant with cover slips before imaging. Cell surface receptor staining To assess cell surface receptors by flow cytometry, cells were harvested, washed in 5% FBS/PBS at a density of 100000 cells per well in a v-bottomed 96 well plate (Nunc) and incubated on ice for 1 hour with the respective primary mouse mAb; Anti-CAR (RmcB, 3022487; Millipore) and anti-αvβ6 (MAB2077Z; Millipore) and matched IgG control were used at a concentration of 1:500 or an matched IgG control. Cells were then washed and incubated on ice for 30 minutes with 1:500 dilution of Alexa-647 labelled goat anti-mouse F(ab’)2 (ThermoFisher; A-21237). Stained cells were fixed using 4% paraformaldehyde prior to measurement by flow cytometry on Accuri C6(BD Biosciences). For flow cytometry, a minimum of 10000 events were acquired. Analysis was performed using FlowJo v10 (FlowJo, LLC) by sequential gating on cell population, singlets and Alexa-647 positive cells. Organoid viability assay Organoids established in culture were mechanically disaggregated into fragments, with a representative population further digested to single cells by incubation in TrypLE for 9 mins at 37°C for counting purposes. Single cell counts were carried out using an automated cell counter (Cell Drop, DeNovix) and used to estimate cell numbers within organoid fragments. Organoid fragments were resuspended in 10 µL media and incubated with viruses at a dose of 5000 vp/cell for 30 minutes at 37°C. Following incubation, tubes were transferred to ice and the medium containing infected organoids (10% final volume) was supplemented with Matrigel (90% final volume), mixed and seeded in 5 uL drops in triplicate in white clear-bottomed 96 well plates.. Plates were incubated at room temperature for 5 minutes, prior to inverting plates and incubating for 1 one hour at 37°C to enable Matrigel polymerisation. Growth medium containing 10 µM ROCK inhibitor, Y-27632, (BD Biosciences) was overlaid on Matrigel domes and incubated under standard tissue culture conditions for 24 hours. Following a 24 hour incubation, medium was removed from wells and replaced with growth medium containing a 0368P/WO As Filed dilution of 5-FC or PBS vehicle control. Cell viability was measured 5 days after drug treatment using Cell Titer Glo (Promega) assay. Cell Titer Glo reagent was added to a total volume of 50 µL per well and placed on a shaker platform (595rpm) for 1 hour at room temperature, protected from light. Luminescence was measured on a multimodal platereader (Biotek) and values expressed as a percentage viability relative to vehicle control cells. Patient derived organoids Patient-derived organoids (PDOs) from pancreatic tumours (PDM38, PDM39) were acquired from the ATCC repository and cultured according to manufacturer’s instructions. We used models and data derived by the Human Cancer Models Initiative (HCMI) ; dbGaP accession number phs001486. HCM-CSHL-0091-C25 (ATCC^® PDM-38^™) and CSHL-0092-C25 (ATCC^® PDM-39^™) PDOs were cultured in Matrigel (Corning, 100 % v/v) and maintained at a seeding density of 0.25 – 1 × 10⁶ cells/ 100 uL of Matrigel per well of a 6-well plate. A complete medium change was carried out every 3-4 days in culture. Organoids were maintained in Advanced DMEM F12 (Gibco) supplemented with HEPES (1%), GlutaMAX (1%), B-27 (1 X), Rspo1 Conditioned media (10%), Wnt-3A conditioned media (50%), Noggin (Peprotech, 100 ng/mL), hEGF (Peprotech, 50 ng/mL), FGF-10 (Peprotech, 100ng/mL), Nicotinamide (1.25 mM,Sigma-Aldrich), N-Acetyl-Cysteine (10 mM, Sigma-Aldrich), Gastrin (100 nM,Sigma- Aldrich), A 83-01 (500 nM, Peprotech). Organoids were split by enzymatic digestion when the appropriate confluence was reached, using TrypLE dissociating agent (Gibco).10 µM ROCKi was added to growth medium for first 3 days after splitting. Statistical Analysis Statistical analyses were performed using GraphPad (San Diego, CA) Prism software. Data are presented as mean ± standard error of the mean unless otherwise specified. Experiments were performed to n=3 independent experiments, unless otherwise stated. Statistical analysis was carried out as indicated and statistical significance is shown as follows; ns = p > 0.05; * = p < 0.05; **; = p < 0.01; *** = p < 0.001; **** = p < 0.0001. RESULTS Replication-deficient Ad5 expressing FCY1/FCU1 infect CAR+ pancreatic cells and sensitise cells to 5-FC treatment in vitro To investigate whether Ad5-mediated expression of cytosine deaminase (FCY1) and a bifunctional chimeric protein encoding cytosine deaminase and UPRTase (FCU1) would 0368P/WO As Filed catalyse the conversion of 5-FC into toxic substrates (using pancreatic cells as our example) we generated two Ad5 vectors bearing the FCY1 or FCU1 gene. The coding sequence of both FCY1 and FCU1 were introduced into a deleted E1 region of Ad5 under the CMV promoter as shown in the schematic of the constructed viruses (Figure 1). Successful insertion of the FCY1 or FCU1 gene was confirmed by sequencing. To assess whether expression of cytosine deaminase (CD) by Ad5-FCY1 or cytosine deaminase/UPRTase by Ad5-FCU1 infection would sensitise cells to 5FC by conversion of enzymes into toxic metabolites 5-FU and 5-FUMP (Figure 1A), respectively, we infected PT45 pancreatic cancer cells which have a high level of CAR expression (Figure 1B, Davies et al., 2021) with Ad5-FCY1 and Ad5-GFP at 500, 1000 and 5000 viral particles/cell (vp/cell) for 24 hours. Cells were exposed to 5-FC treatment at varying concentrations for 3 days prior to assessing cell viability using an ATP-based assay readout. We found that FCY1-infected PT45 (CAR^high) cells were susceptible to 5-FC treatment in a dose-dependent manner compared to non-infected cells, or those infected with Ad5-GFP as an Ad based transgene control (Figure 2A). Transduction of PT45 cells with FCU1 resulted in a greater sensitisation to 5-FC treatment compared to FCY1 infection (approximately log fold change in IC50), corroborating previous findings in the literature demonstrating the potency of CD and UPRTase in combination with 5-FC compared to CD alone (Dias et al ., 2010). Conversely, CAR-negative CHO-K1 cells showed no significant difference in viability in the presence of 5-FC when infected with Ad5-FCY1 or Ad5-FCU1 (Figure 2B) suggesting that the presence of CAR was essential to mediate cytotoxicity in culture. The data generated in the PT45 cell line using Ad5-FCY1 and Ad5-FCU1 could not be used to determine any differences in potency/efficacy in comparison with Ad5NULL-A20-FCY1 or Ad5NULL-A20-FCU1 because the PT45 cell line does not express αvβ6 integrin. Thus, Ad5NULL- A20 cannot infect the PT45 cell line, and no direct comparison could be made as it is only possible to compare activity directly in the same cell line. In this part of the analysis, the PT45 cell line was used as a high CAR expressing positive control to confirm that Ad5-FCY1 and Ad5-FCU1 could infect the cell line and sensitize the cell line to 5-FC treatment. We further evaluated the sensitivities of PANC10.05, BxPC3, CFPAC1 and ASPC1 pancreatic tumour cells after in vitro transduction with the Ad5-FCY1, Ad5-FCU1 or Ad5-GFP vectors, alone or in combination with 5-FC. Overall, 5-FC treatment alone or in combination with Ad5- GFP had no impact on cell viability in all cell lines tested compared with vehicle only control. CAR+ pancreatic cells were sensitised to 5-FC treatment following infection with Ad5-FCY1 (Figure 3A) and Ad5-FCU1 (Figure 3B), with FCU1 infection causing the highest sensitivity 0368P/WO As Filed to 5-FC compared with FCY1. Taken together these data suggest that CAR is essential for the entry of Ad5-FCY1/Ad5-FCU1 into cells to mediate prodrug-dependent toxicity and simultaneous expression of CD and UPRTase can result in a cooperative effect that increases the sensitivity of target cells to 5-FC. Replication-deficient Ad5_NULL-A20 expressing FCY1/FCU1 infect and sensitise αvβ6+ pancreatic cells to 5-FC treatment We engineered Ad5NULL-A20 to express cytosine deaminase (FCY1) and the bifunctional chimeric protein of cytosine deaminase and UPRTase (FCU1). Successful insertion of the FCY1 or FCU1 gene was confirmed by sequencing. We assessed the impact of cells with previously characterised levels of αvβ6 integrin expression (Davies et al., 2021) to 5-FC treatment alone or in combination, following infection with mock, Ad5NULL-A20 transgene control, Ad5NULL-A 20-FCY1 and Ad5NULL-A 20-FCU1 for 24 hours. Cells were treated with 5-FC for a total of 3 days prior to assessing cell viability using an ATP-based assay readout. Pancreatic CFPAC1 cells (αvβ6^high) infected with Ad5 NULL-A20-FCY1 and subjected to varying doses of 5-FC demonstrated an impaired viability compared to mock-infected cells or those infected with Ad5NULL-A20 transgene control. Cell killing activity was enhanced when cells were infected with increasing viral load, with efficient cell killing activity at 5000 vp/cell compared to 500 vp/cell, even at the lowest concentrations of 5-FC. αvβ6^high CFPAC1 cells were further sensitised to 5-FC when infected with Ad5NULL-A20-FCU1 (Figure 4A), with cell viability impaired at the lowest doses of 5-FC (0.01 mM). Conversely, PT45 pancreatic cells, previously shown to express limited αvβ6 integrin expression levels (Davies et al., 2021), showed no significant difference in viability following a combination of Ad5NULL-A20-FCY1 infection and treated with 5-FC compared with mock or transgene control conditions (Figure 4B). Ad5NULL-A20-FCU1 failed to sensitise PT45 (αvβ6^low) cells to 5-FC treatment. We tested a panel of pancreatic cell lines with known levels of αvβ6 integrin (Davies et al., 2021) with Ad5^NULL-A20-FCY1 or Ad5^NULL-A20-FCU1 in combination with 5-FC and found that cells with the highest levels of αvβ6 integrin were more susceptible to treatment (Figure 5, Table 1). Ad5^NULL-A20-FCU1 induced the greatest sensitisation to 5-FC from all vectors tested. Infection of 5000vp/cell of Ad5^NULL-A20-FCU1 led to a log fold difference in overall IC50 values compared to lowest virus titres (500 vp/cell) in αvβ6 integrin+ cells. We further found that IC50 values of cell lines treated with Ad5^NULL-A20-FCU1 were lower compared to those treated with Ad5-FCU1 when comparing the same cell line (it important to note that, due to variability 0368P/WO As Filed between cells lines, direct comparisons between the activity of Ad5NULL-A20-FCU1 and Ad5- FCU1 could only be performed accurately when considered in the context of using the same cell line). 5-FC treatment resulted in IC₅₀ values of approximately 0.1 mM in CFPAC1 cells treated with Ad5-FCU1, compared to IC₅₀ of approximately 0.01 mM in Ad5NULL-A20-FCU1- infected cells (Table 2). We observed that the fold changes in IC₅₀ of CFPAC1 and BxPC3 cell lines, with similar levels of αvβ6 integrin and CAR expression, following transduction with Ad5-FCU1 and Ad5NULL-A20-FCU1 were approximately 10.8 and 26.2 times lower in cells transduced with 5000vp/cell Ad5NULL-A20-FCU1 versus Ad5-FCU1 (Table 2 rows 1 & 2). Given that CFPAC1 and BxPC3 cells had similar receptor expression levels of CAR and αvβ6 integrin, this would suggest that the Ad5NULL-A20- vector results in a lower IC50 and thus a much greater sensitivity to 5-FC compared to the Ad5- vector. This suggests that Ad5NULL-A20- FCU1 is able to selectively infect cells in a αvβ6 integrin dependent manner, resulting in an increased sensitisation to 5-FC, compared to Ad5-FCU1, in pancreatic tumour cells with high expression levels of both αvβ6 integrin and CAR. In Table 3, we show the fold difference in IC50 when the wild-type virus carrying either FCY1 or FCU1 (i.e., Ad5.FCY1 versus Ad5.FCU1) is used to transfect cells prior to 5-FC exposure and, as expected, there is an increase in effect when using FCU1 compared to FCY1. Also, in Table 3 we show the fold difference in IC50 when the Ad5NULL virus carrying either FCY1 or FCU1 (i.e., Ad5NULL-A20.FCY1 versus Ad5NULL-A20.FCU1) is used to transfect cells prior to 5- FC exposure. Similarly, we see an increase in effect when using FCU1 compared to FCY1. As expected, the Ad5NULL-A20 vector, expressing the A20 peptide sequence NAVPNLRGDLQVLAQKVART, bound cells expressing an αvβ6 integrin, and so these cells were sensitised to 5-FC treatment. Conversely, those cells not expressing αvβ6 integrin, or expressing only a small amount of αvβ6 integrin, were less responsive to Ad5NULL-A20 vector. Thus, the cell surface expression pattern of the cells listed in Tables 1-3 determines, in part, the responsiveness of the cells. The data generated in the PT45 cell line using Ad5-FCY1 and Ad5-FCU1 could not be used to determine any differences in potency/efficacy in comparison with Ad5NULL-A20-FCY1 or Ad5NULL-A20-FCU1 because the PT45 cell line does not express αvβ6 integrin. Thus, Ad5^NULL-A20 cannot infect the PT45 cell line and no direct comparison could be made as it is only possible to compare activity directly in the same cell line. In this part of the analysis, the PT45 cell line was used as a high CAR expressing positive control to confirm that Ad5-FCY1 and Ad5-FCU1 could infect the cell line and sensitize the cell line to 5-FC treatment. 0368P/WO As Filed Importantly, when comparing the effective activity IC₅₀ for these vectors in CFPAC1 and BXPC3, the 2 cell lines expressing similar levels of both CAR (the entry receptor for Ad5) and αvβ6 integrin (the entry receptor for Ad5_NULL-A20), FCU1 was substantially, and unexpectedly, better in Ad5_NULL-A20 than Ad5 (Table 2), whereas FCY1 was similarly effective in Ad5 and Ad5_NULL-A20 (Table 1). For example, there was an increase in activity of on average 10-fold for FCU1 versus FCY1 in Ad5 in CFPAC1 at 5000 vp/cell dose, and an increase in activity of an average 20-fold for FCU1 versus FCY1 in Ad5 in BXPC3 at 5000 vp/cell dose (as expected because of the known greater potency of FCU1 compared to FCY1), whereas when using the vector of the inevtion Ad5NULL-A20, there was an average 95-fold increase for FCU1 versus FCY1 in CFPAC1 at 5000 vp/cell dose and a 200-fold increase in BXPC3 at 5000 vp/cell dose. This would suggest the Ad5NULL-A20-FCU1 vector is ~10 times better than the Ad5- FCU1 vector demonstrating an unexpected synergy between Ad5NULL-A20 and FCU1. Ad5NULL-A20-mediated FCU1 expression sensitises mouse pancreatic tumour organoids to 5-FC Given the favourable, tumour-selective targeting observed in vitro, we performed ex vivo studies in organoids derived from the clinically relevant KPC pancreatic genetically engineered mouse model (GEMM). We used the pancreas-specific Pdx1-Cre^ERT LSL-Kras^G12D/+; LSL- Trp53^R172H; Rosa26^LSL-tdRFP (KPC; red fluorescent protein [RFP]) and administered tamoxifen to include Pdx1-Cre recombinase to induce tumour formation with Kras and p53 mutations. Following tumour formation, we generated organoid cultures from KPC tumours (Figure 6). To confirm that αvβ6 expression was retained in the KPC mouse model, we evaluated tumour sections by IHC and stained for αvβ6 integrin and found that KPC mouse tumours had high levels of αvβ6 expression (Figure 7A). We determined the expression levels of αvβ6 integrin in Organoids derived from the KPC mouse (Panc01MO) and found that they further demonstrated high levels of αvβ6 integrin as confirmed by flow cytometry (Figure 7B). To assess whether αvβ6 integrin-expressing KPC organoids could be sensitised to 5-FC treatment following infection with Ad5^NULL-A20-FCU1 as our candidate therapy, organoids cell fragments were exposed to 5000 vp/cell of virus for 24 hours, treated with 5-FC for 5 days and assessed for overall viability. Fluorescence and phase images of Panc01MO demonstrate that organoids were amenable to virus infection, with GFP+ cells observed in all organoid structures infected with Ad5-GFP as a transgene expressing control (Figure 8). We found that infection of Ad5NULL-A20-FCU1 in the absence of prodrug had minimal impact on overall organoid viability as measured by an ATP assay, suggesting that the virus alone was non- 0368P/WO As Filed toxic to the cells. In the presence of 5-FC, a significant effect on overall viability was observed in a dose-dependent manner, with IC₅₀ values at 0.012 mM compared to an IC₅₀ of > 10 mM in mock and Ad5-GFP infection conditions (Figure 8), suggesting a marked and unexpectedly large improvement in sensitivity to 5-FC. We further evaluated the impact of Ad5NULL-A20-FCU1 in Panc01MO using an incucyte assay readout to acquire time lapse images of organoids (Figure 9A) and found that the average organoid size (µm), as an indicator of growth over time, increased in both mock- and Ad5-GFP infected organoids, regardless of 5-FC dose (Figure 9B). However, the combination of infection of Panc01 with Ad5NULL-A20-FCU1 and 5-FC resulted in no overall change in average organoid area over 5 days of treatment in the highest concentrations of drug (Figure 9B) suggesting the combination of Ad5NULL-A20-FCU1 with 5-FC had a detrimental effect on overall organoid growth and resulted in toxicity. Taken together, our data suggest that a combination of virus and drug effectively impair overall viability of pancreatic tumour organoids from a clinically relevant mouse model of pancreatic cancer. Ad5NULL-A20-FCU1 in combination with 5-FC reduces viability in patient derived PDAC organoids. Previous findings have reported on the clinical relevance of patient derived organoids from PDAC samples (Raimondi et al.,2020). We sought to investigate whether pancreatic tumour patient-derived organoids (PDOs) could be infected with an αvβ6 selective virus incorporating CD and UPRTase and sensitised to 5-FC treatment. Previously characterized PDAC-derived organoids were cultured as previously described, with tumour-status of organoids confirmed by DNA sequencing (ATCC HCMI database). To assess the potential of Ad5NULL-A20 and Ad5 vectors to infect PDAC PDOs, we determined the expression levels of αvβ6 integrin and CAR by flow cytometry on single cell digests of organoid structures (Figure 10). In all organoid lines tested, all were positive for αvβ6 integrin expression. This is in corroboration with previous findings in the literature which report >90% PDAC patient histology samples demonstrate high αvβ6 integrin expression (Reader., 2019). CAR was also detected in all organoid lines. Using protocols optimised in KPC-derived mouse organoids, we infected organoid fragments with Ad5-GFP or Ad5^NULL-A20-FCU1 for 24 hours prior to treatment with or without the prodrug 5-FC . We compared the effects of Ad5-GFP, Ad5^NULL-A20-FCU1 and 5-FC in combination or alone in different two PDAC organoid lines derived from 2 PDAC patients. Phase-contrast and corresponding fluorescence images of PDM38 and PDM-39 show that organoids were 0368P/WO As Filed successfully infected with Ad5-GFP using this method. We found that organoids alone or infected with Ad5-GFP and treated with 0mM and 10 mM 5-FC exhibited few differences in morphologies and overall size in culture as shown by representative image panels (Figure 10). Fewer organoids were detected in the presence of highest concentration of 5-FC compared to transgene vector control conditions. Using an ATP-based assay readout, we found that organoid viability was diminished when treated with Ad5NULL-A20-FCU1 in combination with 5-FC, resulting in IC₅₀ values of 0.02 mM and 0.0018 mM in PDM-38 and PDM-39, respectively. Given that PDM-38 showed marked sensitivity to FCU1 expression and 5-FC combination, this would suggest that the presence of a subset αvβ6 integrin is sufficient to cause toxicity via a bystander effect, corroborating previous findings in the literature (Dias et al., 2010). CFPAC1 pancreatic cancer cells are sensitised to FCU1-mediated bystander effects. We further evaluated whether FCU1-mediated conversion of 5-FC to 5-FU and 5-FUMP following transduction could impact on the overall health of neighbouring untransduced cells. CFPAC1 cells, which exhibited relatively similar values of CAR and αvβ6 integrin positive cells, were transduced with 1000 vp/cell of Ad5-FCU1 or Ad5NULL-A20-FCU1, seeded in a mixed population with naïve CFPAC1 cells, then treated with 5-FC. No significant changes in overall viability were observed in mixed populations of naïve and transduced cells treated with 0 mM 5-FC compared to control conditions (Figure 11A). Sensitisation to 5-FC was observed when a small percentage of the overall population were transduced with Ad5-FCU1 or Ad5NULL-A20- FCU1(Figure 11A). We further analysed the overall cell viability of CFPAC1 cells following exposure to supernatants collected from Ad5-FCU1 or Ad5NULL-A20-FCU1 transduced cells treated with and without 5-FC. Conditioned media from Ad5-FCU1 or Ad5NULL-A20-FCU1 transduced cells without 5-FC had no impact on the overall viability of CFPAC1 cells. CFPAC1 cell viability was reduced when treated with supernatants of transduced cells exposed to 5-FC (Figure 11B). Overall, this demonstrated that Ad5-FCU1 or Ad5NULL-A20-FCU1 mediate a conversion capable of eliciting toxicity to neighbouring naïve cells in vitro. This bystander effect was slightly more effective in cells transduced with Ad5NULL-A20-FCU1 compared to Ad5- FCU1. DISCUSSION The combination of enzyme-prodrug systems for cancer therapy has previously been described in the literature but is somewhat limited in its capacity to effectively and selectively transduce tumour cells and, as a result, has a low significant therapeutic effect. Therefore, we aimed to identify whether arming a tumour selective Ad5-based vector, Ad5NULL-A20, which 0368P/WO As Filed has been shown to selectively infect pancreatic cells with αvβ6 integrin (Davies et al), with FCY1 and FCU1 transgenes in combination with 5-FC, had the capacity to confer selective cytotoxicity in tumour cells. In this study, we generated Ad5 and Ad5NULL-A20 vectors to express FCY1 and FCU1 transgenes and evaluated their effect on viability in a panel of pancreatic cell lines with varying known levels of CAR and αvβ6 integrin. We found that the Ad5 mediated transfer of FCY1 into tumour cells can successfully sensitize CAR+ cells to 5-FC treatment and cause growth arrest in vitro. We found the bifunctional protein (FCU1) that combines the two enzymatic activities of CD and UPRTase, increased in vitro sensitivity to 5-FC compared to FCY1-transduced cells, corroborating previous findings in the literature (Dias et al.,2010). Replication-deficient Ad5NULL-A20 expressing FCY1/FCU1 was able to successfully infect and sensitise αvβ6+ pancreatic cells to 5-FC treatment. We found limited cytotoxicity in cells infected with Ad5- or Ad5NULL-A20- transgene controls in combination with 5-FC in CAR+ and αvβ6 integrin+ cells, respectively. Previous studies in the literature have demonstrated some efficacy of using a combination of CD/CD and UPRTase with a non-toxic prodrug,5-FC, to induce cytotoxicity in cancer cell lines. Erbs et al (2000) and Dias et al (2010) have previously reported Ad5-based vectors armed with FCU1, and an oncolytic Ad5-based FCU1 vector which show the capacity to reduce tumour growth. We aimed to further the tumour selectivity and found that incorporating suicide transgenes into replication deficient Ad5NULL-A20 augmented tumour cell killing in vitro. Using pancreatic cell lines expressing similar levels of CAR (the entry receptor for Ad5) and αvβ6 integrin (the entry receptor for Ad5NULL-A20), we found that Ad5NULL-A20-FCU1 was on average 20 - 95-fold improved in terms of IC50 values compared to Ad5NULL-A20-FCY1, this compares with only a 4 - 20-fold average improvement for Ad5-FCU1 over Ad5-FCY1. This unexpected synergistic effect observed only with Ad5NULL-A20-FCU1 has important implications for the development of improved therapies that can deliver toxic drugs locally in tumours. Based on our in vitro results, we sought to test our platform in ex vivo 3D organoids from relevant pre-clinical sources. We found that KPC mouse model organoids, previously found to effectively model multiple features associated with PDAC (Boj et al 2015), retained similar αvβ6 integrin expression levels to corresponding in vivo tissues, and were amenable to Ad- based infections as shown by GFP positive cells following infection. The infection of Ad5NULL- A20-FCU1 and 5-FC combination also resulted in a significant effect on overall organoid viability, even at low doses of pro-drug. We further used patient derived pancreatic ductal 0368P/WO As Filed adenocarcinoma organoids. The addition of 5-FC to the Ad5NULL-A20-FCU1-infected organoids led to a significant decrease in organoid viability in comparison to mock- or Ad5-/ Ad5NULL-A20- transgene controls or 5-FC alone. This study has shown that infections with replication-deficient viruses is possible in organoid culture formats, which could be further expanded to other tumour types. In summary, in wildtype Ad5, when expressing FCY1 or FCU1 cells were sensitised to the prodrug 5-FC, with FCU1 better than FCY1 as expected. Cells lacking the binding receptor CAR were not sensitised. Similarly, for Ad5NULL-A20, when expressing FCY1 or FCU1 cells were sensitised to the prodrug 5-FC, with FCU1 better than FCY1 as expected. Cells lacking the binding receptor αvβ6 integrin were not sensitised. However, when comparing the effective activity IC50 for these vectors, FCU1 was substantially, and unexpectedly, better in Ad5NULL-A20 compared to Ad5 in cells expressing similar CAR and αvβ6 integrin levels (Table 2), whereas FCY1 was similarly effective in both Ad5NULL-A20 compared to Ad5 (Table 1). These data demonstrate an unexpected synergistic effect when only and specifically combining Ad5NULL-A20 with FCU1. Therefore, the superior targeting to cancer cells with Ad5NULL-A20, along with the specific transgene, appears to offer a selective superior therapy that is notably improved over other vectors. In summary, Ad5NULL-A20-FCU1 results in improved antitumour activity in vitro and ex vivo with limited toxicity observed in the highest doses of 5-FC alone. REFERENCES Uusi-Kerttula H, Davies JA, Thompson JM, Wongthida P, Evgin L, Shim KG, Bradshaw A, Baker AT, Rizkallah PJ, Jones R, Hanna L, Hudson E, Vile RG, Chester JD, Parker AL. Ad5_NULL-A20: A Tropism-Modified, αvβ6 Integrin-Selective Oncolytic Adenovirus for Epithelial Ovarian Cancer Therapies. Clin Cancer Res.2018 Sep 1;24(17):4215-4224. doi: 10.1158/1078-0432.CCR-18-1089. Epub 2018 May 24. PMID: 29798908. Davies JA, Marlow G, Uusi-Kerttula HK, Seaton G, Piggott L, Badder LM, Clarkson RWE, Chester JD, Parker AL. Efficient Intravenous Tumor Targeting Using the αvβ6 Integrin- Selective Precision Virotherapy Ad5_NULL-A20. Viruses.2021 May 8;13(5):864. doi: 10.3390/v13050864. PMID: 34066836; PMCID: PMC8151668. Dias JD, Liikanen I, Guse K, Foloppe J, Sloniecka M, Diaconu I, Rantanen V, Eriksson M, Hakkarainen T, Lusky M, Erbs P, Escutenaire S, Kanerva A, Pesonen S, Cerullo V, Hemminki A. Targeted chemotherapy for head and neck cancer with a chimeric oncolytic adenovirus coding for bifunctional suicide protein FCU1. Clin Cancer Res.2010 May 1;16(9):2540-9. doi: 10.1158/1078-0432.CCR-09-2974. Epub 2010 Apr 13. PMID: 20388844. 0368P/WO As Filed Raimondi G, Mato-Berciano A, Pascual-Sabater S, Rovira-Rigau M, Cuatrecasas M, Fondevila C, Sánchez-Cabús S, Begthel H, Boj SF, Clevers H, Fillat C. Patient-derived pancreatic tumour organoids identify therapeutic responses to oncolytic adenoviruses. EBioMedicine.2020 Jun;56:102786. doi: 10.1016/j.ebiom.2020.102786. Epub 2020 May 24. PMID: 32460166; PMCID: PMC7251378. Reader CS, Vallath S, Steele CW, Haider S, Brentnall A, Desai A, Moore KM, Jamieson NB, Chang D, Bailey P, Scarpa A, Lawlor R, Chelala C, Keyse SM, Biankin A, Morton JP, Evans TJ, Barry ST, Sansom OJ, Kocher HM, Marshall JF. The integrin αvβ6 drives pancreatic cancer through diverse mechanisms and represents an effective target for therapy. J Pathol. 2019 Nov;249(3):332-342. doi: 10.1002/path.5320. Epub 2019 Jul 30. PMID: 31259422; PMCID: PMC6852434. Erbs P, Requlier E, Kints J, Leroy P, Poitevin Y, Exinger F, Jund R, Mehtali M; In Vivo Cancer Gene Therapy by Adenovirus-mediated Transfer of a Bifunctional Yeast Cytosine Deaminase/Uracil Phosphoribosyltransferase Fusion Gene. Cancer Res 15 July 2000; 60 (14): 3813–3822. Boj, Sylvia F. Chang-Il Hwang, Lindsey A. Baker, Iok In Christine Chio, Dannielle D. Engle, Vincenzo Corbo, Myrthe Jager, Mariano Ponz-Sarvise, Hervé Tiriac, Mona S. Spector, Ana Gracanin, Tobiloba Oni, Kenneth H. Yu, Ruben van Boxtel, Meritxell Huch, Keith D. Rivera, John P. Wilson, Michael E. Feigin, Daniel Öhlund, Abram Handly-Santana, Christine M. Ardito-Abraham, Michael Ludwig, Ela Elyada, Brinda Alagesan, Giulia Biffi, Georgi N. Yordanov, Bethany Delcuze, Brianna Creighton, Kevin Wright, Youngkyu Park, Folkert H.M. Morsink, I. Quintus Molenaar, Inne H. Borel Rinkes, Edwin Cuppen, Yuan Hao, Ying Jin, Isaac J. Nijman, Christine Iacobuzio-Donahue, Steven D. Leach, Darryl J. Pappin, Molly Hammell, David S. Klimstra, Olca Basturk, Ralph H. Hruban, George Johan Offerhaus, Robert G.J. Vries, Hans Clevers, David A. Tuveson, Organoid Models of Human and Mouse Ductal Pancreatic Cancer,Cell, 2015. Volume 160, Issues 1–2, Hill William, Andreas Zaragkoulias, Beatriz Salvador-Barbero, Geraint J. Parfitt, Markella Alatsatianos, Ana Padilha, Sean Porazinski, Thomas E. Woolley, Jennifer P. Morton, Owen J. Sansom, Catherine Hogan; EPHA2-dependent outcompetition of KRASG12D mutant cells by wild-type neighbors in the adult pancreas,Current Biology,Volume 31, Issue 12,2021, Pages 2550-2560.e5,

Claims

0368P/WO As Filed Claims 1. A a viral vector of Ad5 serotype adenovirus (herein referred to as Ad5_NULL) modified to comprise: a) at least one of I421G, T423N, E424S, E450Q or L426Y point mutation(s) in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) at least one of S408E or P409A point mutation(s) in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); and c) at least one of D342E or D342A point mutation(s) in the penton integrin binding motif Arg-Gly-Asp (RGD) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin; and wherein said vector further comprises or encodes or expresses the FCU1 transgene. 2. The viral vector according to claim 1 wherein the at least one HVR7 mutation comprises or consists of at least one of the following point mutations: I421G, T423N, E424S, and L426Y. 3. The viral vector according to any preceding claim wherein said at least one KO1 mutation comprises or consists of S408E and P409A point mutations. 4. The viral vector according to any preceding claim wherein at least one RGD mutation comprises a D342E point mutation. 5. The viral vector according to any preceding claim wherein said viral vector is further modified to include at least one cell targeting modification or sequence that selectively targets specific target cells. 6. The viral vector according to claim 5 wherein said viral vector comprises at least one NGR (containing) peptide motif to bind aminopeptidase N wherein said NGR is in the HI loop of the adenoviral fiber protein; or at least one YSA (containing) peptide motif to bind to pan-cancer marker EphA2, wherein said YSA is in the chimeric fiber, or at least one cancer targeting antibody or at least one growth factor antibody or at least one matrix degrading enzyme. 0368P/WO As Filed 7. The viral vector according to claim 5 wherein said cell targeting modification comprises insertion or expression of an αvβ6 integrin binding peptide or the A20 peptide sequence NAVPNLRGDLQVLAQKVART (SEQ ID NO: 1) into or by the virus. 8. The viral vector according to claim 7 wherein the A20 peptide sequence is inserted into or expressed in the viral fiber knob HI loop. 9. The viral vector according to any preceding claim wherein said viral vector is further modified to include at least one growth factor antibody. 10. The viral vector according to claim 9 wherein the growth factor antibody is linked to the vector using a chemical linkage and then the antibody is used as a targeting modification. 11. The viral vector according to any preceding claim wherein said viral vector is further modified to include at least one matrix degrading enzyme. 12. The viral vector according to any preceding claim wherein said viral vector (Ad5NULL- A20) comprises: a) at least one of I421G, T423N, E424S, E450Q or L426Y point mutation(s) in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) at least one of S408E or P409A point mutation(s) in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); c) at least one of D342E or D342A point mutation(s) in the penton integrin binding motif Arg-Gly-Asp (RGD) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin; and d) presentation or expression of the A20 peptide sequence NAVPNLRGDLQVLAQKVART in the viral fiber knob HI loop; and wherein said modified vector further comprises or encodes the FCU1 transgene. 13. The viral vector according to claim 12 wherein said viral vector (Ad5NULL-A20) comprises: 0368P/WO As Filed a) I421G, T423N, E424S, and L426Y point mutations in the hexon hypervariable region 7 (HVR7 mutation) wherein said mutation prevents virus binding with coagulation factor 10 (FX); b) S408E and P409A point mutations in the fiber knob region AB loop (KO1 mutation) wherein said mutation prevents virus binding with the coxsackie and adenovirus receptor (CAR); c) D342E point mutation in the penton integrin binding motif Arg-Gly-Asp (to produce RGE mutation) wherein said mutation prevents virus binding with αVβ3/αVβ5 integrin; and d) insertion or expression of the A20 peptide sequence NAVPNLRGDLQVLAQKVART in the viral fiber knob HI loop; and wherein said vector further comprises or encodes the FCU1 transgene. 14. The viral vector according to any preceding claim wherein said vector is further modified to include at least one further transgene encoding a molecule or agent. 15. The viral vector according to any preceding claim for use as a medicament. 16. The viral vector according to any one of claims 1-14 for use in the treatment of cancer, fibrosis, aberrant wound healing such as chronic wounds, or epidermolysis bullosa.. 17. The viral vector according to any one of claims 1-14 for use in the manufacture of a medicament to treat cancer, fibrosis, aberrant wound healing such as chronic wounds, or epidermolysis bullosa. 18. The viral vector according to claim 16 or 17 wherein the cancer is selected from the group comprising or consisting of: nasopharyngeal cancer, synovial cancer, hepatocellular cancer, renal cancer, cancer of connective tissues, melanoma, lung cancer, bowel cancer, colon cancer, rectal cancer, colorectal cancer, brain cancer, throat cancer, oral cancer, liver cancer, bone cancer, pancreatic cancer, choriocarcinoma, gastrinoma, pheochromocytoma, prolactinoma, T-cell leukemia/lymphoma, neuroma, von Hippel-Lindau disease, Zollinger-Ellison syndrome, adrenal cancer, anal cancer, bile duct cancer, bladder cancer, ureter cancer, oligodendroglioma, neuroblastoma, meningioma, spinal cord tumor, osteochondroma, chondrosarcoma, Ewing's sarcoma, cancer of unknown primary site, carcinoid, carcinoid of gastrointestinal tract, fibrosarcoma, breast cancer, Paget's 0368P/WO As Filed disease, cervical cancer, colorectal cancer, rectal cancer, esophagus cancer, gall bladder cancer, head cancer, eye cancer, neck cancer, kidney cancer, Wilms' tumor, Kaposi's sarcoma, prostate cancer, testicular cancer, Hodgkin's disease, non- Hodgkin's lymphoma, skin cancer, mesothelioma, multiple myeloma, ovarian cancer, endocrine pancreatic cancer, glucagonoma, parathyroid cancer, penis cancer, pituitary cancer, soft tissue sarcoma, retinoblastoma, small intestine cancer, stomach cancer, thymus cancer, thyroid cancer, trophoblastic cancer, hydatidiform mole, uterine cancer, endometrial cancer, vagina cancer, vulva cancer, acoustic neuroma, mycosis fungoides, insulinoma, carcinoid syndrome, somatostatinoma, gum cancer, heart cancer, lip cancer, meninges cancer, mouth cancer, nerve cancer, palate cancer, parotid gland cancer, peritoneum cancer, pharynx cancer, pleural cancer, salivary gland cancer, tongue cancer and tonsil cancer. 19. A pharmaceutical composition comprising the viral vector according to any one of claims 1-14 a pharmaceutically acceptable carrier, adjuvant, diluent or excipient. 20. A combination therapeutic comprising the viral vector according to any one of claims 1-14 and at least one further therapeutic agent, optionally the pro-drug 5- Fluorocytosine (5-FC). 21. A method of treating cancer, fibrosis, aberrant wound healing such as chronic wounds, or epidermolysis bullosa comprising administering an effective amount of the viral vector according to any one of claims 1-14, or the pharmaceutical composition according to claim 19 or the combination therapeutic according to claim 20 to a patient in need thereof.