CO-ADMINISTRATION OF A PARVOVIRUS AND A CYTOKINE FOR THERAPY OF PANCREATIC CANCER

Abstract

The application relates to a combination of a parvovirus and a cytokine, preferably IFNγ, for use in treating pancreatic cancer (PDAC), in particular a terminal stage of this disease.

Description

INCORPORATION BY REFERENCE

All documents cited or referenced herein (“herein cited documents”), and all documents cited or referenced in herein cited documents, together with any manufacturer's instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention. More specifically, all referenced documents are incorporated by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a combination of a parvovirus and a cytokine, preferably IFNγ, for use in treating pancreatic cancer, in particular a terminal stage of this disease.

BACKGROUND OF THE INVENTION

Pancreatic cancer is an aggressive malignancy with one of the worst outcomes among all cancers. For all stages combined, the 5-year relative survival rate is only 5% (Ahmedin J, Siegel R, Ward E, Hao Y, Xu J and Thun M. Cancer Statistics 2009. CA Cancer J Clin 2009;59:225-49). The radical surgery (Whipple's operation) is the only curative option in this aggressive tumor but can be offered to less than 20% of pancreatic ductal adenocarcinoma cancer (PDAC) patients. Chemotherapy can be used as adjuvant to surgery or in advanced stage pancreatic cancer where, in a small group of patients, it offers real benefit in terms of survival and quality of life (Katz M H, Fleming J B, Lee J E, Pisters P W. Current status of adjuvant therapy for pancreatic cancer. Oncologist 2010;15:1205-13). Nevertheless, the therapeutic options for PDAC patients, especially these with peritoneal carcinosis, are lacking.

Novel virus-based anticancer therapies involve the use of viruses either as replicating oncolytic agents, or as recombinant vectors for gene transfer (Kirn D H, McCormick F. Replicating viruses as selective cancer therapeutics Mol Med Today 1996;2:519-527). The autonomous parvoviruses MVMp and H-1 belong to a group of small (˜5 kb) non-integrating single-stranded DNA viruses. Their oncotropic and oncotoxic properties make them promising candidates for both types of applications (Cornelis J J, Haag A, Kornfeld C et al. Autonomous parvovirus vectors In: Cid-Arregui A, Garcia-Garranca A, eds Viral Vectors: Basic Science and Gene Therapy Natick, M A: Eaton Publishing 2000;97-118). Recently it could be demonstrated that applying H-1PV as mono-therapy or as second-line treatment after gemcitabine chemotherapy, caused the reduction of tumor growth, prolonged the survival of rats bearing pre-established pancreatic tumors and led to the suppression of metastases (Angelova A L, Aprahamian M, Grekova S P, Hajri A, Leuchs B, Giese N A, et al. Improvement of gemcitabine-based therapy of pancreatic carcinoma by means of oncolytic parvovirus H-1PV. Clin Cancer Res 2009;15:511-9). Furthermore, it was found that immunological mechanisms are involved in the anticancer activity of H-1PV with a strong correlation between the therapeutic effect of the virus and IFN-γ expression in the draining lymph nodes of pancreatic tumors (Grekova S, Aprahamian M, Giese N, Schmitt S, Giese T, Falk C S, et al. Immune cells participate in the oncosuppressive activity of parvovirus H-1PV and are activated as a result of their abortive infection with this agent. Cancer Biol Ther 2011;10:1280-9).

Despite the impressive results achieved the anticancer efficacy of the most promising parvovirus candidates for human clinical applications (including H-1PV) needs to be improved, e.g., as regards the extension of life span after diagnosis and as regards particular tumors like pancreatic tumors.

Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide means for an improved parvovirus-based therapy. According to the invention this may achieved by the subject matters defined in the claims.

Oncolytic viruses with their capacity to specifically replicate in and kill tumor cells emerged as a novel class of cancer therapeutics. Rat oncolytic parvovirus (H-1PV) was used to treat different types of cancer in preclinical settings and was lately successfully combined with standard gemcitabine chemotherapy in treating pancreatic ductal adenocarcinoma in rats (PDAC).

The experiments resulting in the present invention are based on an idea that the therapeutic properties of H-1PV may be boosted with IFNγ for the treatment of late incurable stages of PDAC like peritoneal carcinosis. Rats bearing established orthotopic pancreatic carcinomas with peritoneal metastases were treated with a single intratumoral (i.t.) or intraperitoneal (i.p.) injection of 5×10⁸ plaque forming units of H-1PV with or without concomitant IFNy application. Intratumoral injection proved to be more effective than the intraperitoneal route in controlling the growth of both the primary pancreatic tumors and peritoneal carcinosis, accompanied by migration of virus from primary to metastatic deposits.

Concomitant i.p. treatment of H-1PV with recIFNy resulted in improved therapeutic effect yielding an extended animal survival, compared to i.p. treatment with H-1PV alone. IFNy application enhanced the H-1PV-induced peritoneal macrophage and splenocyte responses against tumor cells while causing a significant reduction in the titers of H1-PV-neutralising antibodies in ascitic fluid. Thus, IFNγ co-application together with H-1PV might be considered as a novel therapeutic option to improve the survival of PDAC patients with peritoneal carcinosis.

Accordingly, it is an object of the invention to not encompass within the invention any previously known product, process of making the product, or method of using the product such that Applicants reserve the right and hereby disclose a disclaimer of any previously known product, process, or method. It is further noted that the invention does not intend to encompass within the scope of the invention any product, process, or making of the product or method of using the product, which does not meet the written description and enablement requirements of the USPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of the EPC), such that Applicants reserve the right and hereby disclose a disclaimer of any previously described product, process of making the product, or method of using the product.

It is noted that in this disclosure and particularly in the claims and/or paragraphs, terms such as “comprises”, “comprised”, “comprising” and the like can have the meaning attributed to it in U.S. Patent law; e.g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of” and “consists essentially of” have the meaning ascribed to them in U.S. Patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the invention.

These and other embodiments are disclosed or are obvious from and encompassed by, the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example, but not intended to limit the invention solely to the specific embodiments described, may best be understood in conjunction with the accompanying drawings.

FIG. 1: Impact of IFNy addition or depletion on H-1PV immunomodulating activity. (A) Macrophages were isolated from the peritoneal cavity of four groups (n=3) of tumor bearing Lewis rats treated either with PBS (mock) or with an intratumoral injection of 5×10⁸ pfu/rat of H-1PV (H-1PV IT) combined either with an antibody against IFNγ (H-1PV IT+aIFNy) or recombinant IFNγ (H-1PV IT+recIFNγ). Cells were plated in 48-well plates at a density of 5×10⁵ cells per well and stimulated or not with LPS. TNFα production in the supernatants was measured 24 hrs later by ELISA. Average values and standard deviations are shown. (B) Peritoneal macrophages (5×10⁵/well) from the same groups of rats were cocultured or not with 1×10⁵ HA-RPC cells at a 5:1 ratio in 48-well plates and the release of interleukins −10 and −12 was measured by ELISA. Mean cytokine ratios and standard deviations are presented. (C) Single cell suspensions of rat splenocytes were labeled with CFSE, plated in 24 well plates at 1×10⁶ cells/well and cocultured or not with 2×10⁵ HA-RPC cells at a 5:1 ratio. 48 hrs later cells were harvested and processed for FACS analysis of proliferation. All data were median from three animals from triplicate wells. Differences were considered significant at p values below 0.05.

FIG. 2: Therapeutic effects of H-1PV+IFNγ combination and virus distribution. (A) Lewis rats (n=28) bearing simultaneously induced orthotopic tumors and peritoneal metastases were divided into four groups (n=7) and either left untreated (Control), inoculated i.t. (H-1PV intratumoral) or i.p (H-1PV intraperitoneal) with H-1PV in the absence or presence of recIFNy (H-1PV+IFNγ intraperitoneal). After the sacrifice of two animals 1 week after treatment, the survival of five rats from each group was followed up to six months after tumor induction when animals were sacrificed. Median values were considered significant at p values below 0.05. (B) Two animals per group were sacrificed 1 week after H-1PV and/or IFNγ treatments. Total RNA was extracted from visible tumors and metastases, converted to cDNA and subjected to RT-PCRs to evaluate the presence of H-1PV DNA/unspliced mRNA and b-actin transcripts, using respective primers. The abbreviations for the route and type of treatment are indicated on the figure. The source of the material (Tumour or Metastasis) is indicated in superscript.

FIG. 3: Macrophage activation after H-1PV+IFNγ combined treatment. Macrophages were isolated from the peritoneal cavity of the H-1PV and H-1PV+IFNγ intraperitoneally injected rats, plated at 5×10⁵/well in 48 well plates and cocultured or not with 1×10⁵ HA-RPC cells. The ratios of TNFα and IL-10 in supernatants were determined 24 hrs later by ELISA.

FIG. 4: Influence of IFNγ application on the generation of virus neutralizing antibodies. (A) Serum and ascitic fluid were collected from all groups of virus-treated rats (see FIG. 2) and the titers of virus neutralizing antibodies (αH-1PV) were determined using cytotoxicity protection assay on NB324K cells. The titers are expressed as the percentage of antivirus protection offered by serum or ascitis dilutions compared to mock infected cells. (B) Two groups of metastasis bearing rats were treated with two intraperitoneal injections of H-1PV (3×10⁸ pfu/injection per animal) spanning four weeks between them, with or without intermediate recIFNγ i.p. inoculation. Titers of αH-1PV in ascitic fluids were determined 10-30 days after the second H-1PV i.p. injection and expressed as indicated above.

FIG. 5: Release of TNFα from PDAC and PBMC cocultures after H-1PV+IFNγ treatment. The indicated pancreatic cancer cell lines were seeded into 10 cm² dishes at 1.5×10⁶ cells/dish and infected or not with H-1PV at an MOI of 10 pfu/cell. 24 hpi cells were harvested and plated onto pre-isolated PBMCs in 48 well plates at a ratio of PDAC:PBMC 1:5. The cocultures were treated or not with 50 UI/ml of human recombinant IFNγ and the release of TNFα was measured in supernatants 24 hrs later by ELISA. Mock or H-1PV infected (MOI 10) monocultures of PBMCs served as controls. The indicated values are average of at least three independent experiments. SD values are shown.

DETAILED DESCRIPTION OF THE INVENTION

Thus, the present invention provides a combination of a parvovirus and a cytokine, preferably a parvovirus and a cytokine as separate entities, e.g. in separate containers, for use in treating pancreatic cancer.

This combination of compounds is particularly useful for treating a terminal stage of pancreatic cancer. “Terminal stage” means a disease that cannot be cured or adequately treated and that is reasonably expected to result in the death of the patient within a relatively short period of time, e.g. within some weeks or months. The combination of compounds is suitable for treating in particular an incurable stage, like peritoneal carcinosis. Peritoneal carcinosis represents the advanced evolutive stage of several tumors that develop into abdominal organs, such as colon, ovary, appendix, stomach, pancreas and liver. When the disease increases, the tumoral cells reach and affect the membrane covering the same organs (visceral peritoneum). Once this “barrier” has been passed, the affected cells are able to move into the abdominal cavity, carried by the peritoneal fluid. Even in mesothelioma cases that affect directly the peritoneum, tumoral cells can break off the membrane and fall into the peritoneal fluid. The tumoral cells present into the liquid can die or survive feeding on substances contained in the same liquid. These cells tend to accumulate in those points of greater liquid readsorption, creating agglomerates that grow more and more, spreading into the whole abdomen and originating the carcinosis.

The term “parvovirus” as used herein comprises wild-type or modified replication-competent derivatives thereof, as well as related viruses or vectors based on such viruses or derivatives. Suitable parvoviruses, derivatives, etc. as well as cells which can be used for actively producing said parvoviruses and which are useful for therapy, are readily determinable within the skill of the art based on the disclosure herein, without undue empirical effort. Rodent parvoviruses are preferred. Particularly preferred are the following rodent parvoviruses: H1 (H1-PV), LuIII, Mouse minute virus (MMV), Mouse parvovirus (MPV), Rat minute virus (RMV), Rat parvovirus (RPV) and Rat virus (RV).

Patients treatable by the combination of agents according to the invention include humans as well as non-human animals. Examples of the latter include, without limitation, animals such as cows, sheep, pigs, horses, dogs, and cats.

As used herein, the term “cytokine” relates to a category of signalling molecules that are used extensively in cellular communication. They comprise proteins, peptides, or glycoproteins. The term cytokine encompasses a large family of polypeptide regulators that are produced widely throughout the body by cells of diverse embryological origin. The action of cytokines may be autocrine, paracrine, and endocrine. All cytokines are critical to the development and functioning of both the innate and adaptive immune response. They are often secreted by immune cells that have encountered a pathogen, thereby activating and recruiting further immune cells to increase the system's response to the pathogen. Relying on the assays shown in Examples 2 to 5 the person skilled in the art is in a position to select cytokines that show beneficial effects when administrated according to the present invention.

Preferably, the cytokine of the present invention is an interferon. All interferons (IFNs) are natural cell-signalling proteins produced by the cells of the immune system of most vertebrates in response to challenges such as viruses, parasites and tumor cells. Interferons are produced by a wide variety of cells in response to the presence of double-stranded RNA, a key indicator of viral infection. Interferons assist the immune response by inhibiting viral replication within host cells, activating natural killer cells and macrophages, increasing antigen presentation to lymphocytes, and inducing the resistance of host cells to viral infection. All interferons in general have several effects in common and, accordingly, the results obtained by use of IFN-γ in combination with a parvovirus, preferably H1-PV, might apply to further interferons. Interferons are antiviral and possess antioncogenic properties, macrophage and natural killer cell activation, and enhancement of major histocompatibility complex glycoprotein classes I and II, and thus presentation of foreign (microbial) peptides to T cells. The production of interferons is induced in response to microbes such as viruses and bacteria and their products (viral glycoproteins, viral RNA, bacterial endotoxin, bacterial flagella, CpG sites), as well as mitogens and other cytokines, for example interleukin 1, interleukin 2, interleukin-12, tumor necrosis factor and colony-stimulating factor, that are synthesised in the response to the appearance of various antigens in the body. Their metabolism and excretion take place mainly in the liver and kidneys. They rarely pass the placenta but they can cross the blood-brain barrier.

There are three major classes of interferons that have been described for humans:

(a) Interferon type I: The type I interferons present in humans are IFN-α, IFN-β and IFN-ω.

(b) Interferon type II: In humans this is IFN-γ.

(c) Interferon type III: Signal through a receptor complex consisting of IL10R2 (also called CRF2-4) and IFNLR1 (also called CRF2-12).

In a preferred embodiment of the present invention, the interferon is interferon-γ (IFNγ).

Preferably, for the therapeutic use of the present invention the parvovirus and the cytokine are present in an effective dose and combined with a pharmaceutically acceptable carrier. “Pharmaceutically acceptable” is meant to encompass any carrier, which does not interfere with the effectiveness of the biological activity of the active ingredients and that is not toxic to the patient to whom it is administered. Examples of suitable pharmaceutical carriers are well known in the art and include phosphate buffered saline solutions, water, emulsions, such as oil/water emulsions, various types of wetting agents, sterile solutions etc. Such carriers can be formulated by conventional methods and can be administered to the subject at an effective dose.

An “effective dose” refers to amounts of the active ingredients that are sufficient to affect the course and the severity of the tumor, leading to the reduction or remission of such pathology. An “effective dose” useful for treating and/or preventing these diseases may be determined using methods known to one skilled in the art (see for example, Fingl et al., The Pharmocological Basis of Therapeutics, Goodman and Gilman, eds. Macmillan Publishing Co., New York, pp. 1-46 ((1975)).

Preferred doses of the parvovirus are in the range of about 10⁸ to 10⁹ pfu (single injection) in rats and of the cytokine, in particular IFNy, in the range of about 10⁵ to 10⁶ IU (single injection). For humans the preferred effective dose of the parvovirus is approximately 10¹¹ pfu and of the cytokine (e.g. IFNγ) about 2×10⁶ to 10⁸IU.

Additional pharmaceutically compatible carriers can include gels, bioasorbable matrix materials, implantation elements containing the therapeutic agent, or any other suitable vehicle, delivery or dispensing means or material(s).

Administration of the compounds may be effected by different ways, e.g. by intravenous, intraperetoneal, subcutaneous, intramuscular, topical or intradermal administration. The route of administration, of course, depends on the kind of therapy and the kind of compounds contained in the pharmaceutical composition. The dosage regimen of the parvovirus and the cytokine is readily determinable within the skill of the art, by the attending physician based on patient data, observations and other clinical factors, including for example the patient's size, body surface area, age, sex, the particular parvovirus to be administered, the time and route of administration, the tumor type and characteristics, general health of the patient, and other drug therapies to which the patient is being subjected.

If the parvovirus comprises infectious virus particles with the ability to penetrate through the blood-brain barrier, treatment can be performed or at least initiated by intravenous injection of the parvovirus, e.g., H1 virus. As another specific administration technique, the parvovirus (virus, vector and/or cell agent) containing composition can be administered to the patient from a source implanted in the patient. For example, a catheter, e.g., of silicone or other biocompatible material, can be connected to a small subcutaneous reservoir (Rickham reservoir) installed in the patient during tumor removal or by a separate procedure, to permit the parvovirus containing composition to be injected locally at various times without further surgical intervention. The parvovirus or derived vectors containing composition can also be injected into the tumor by stereotactic surgical techniques or by neuronavigation targeting techniques. Administration of the parvovirus containing compositions can also be performed by continuous infusion of viral particles or fluids containing viral particles through implanted catheters at low flow rates using suitable pump systems, e.g., peristaltic infusion pumps or convection enhanced delivery (CED) pumps.

As yet another method of administration of the parvovirus containing composition is from an implanted article constructed and arranged to dispense the parvovirus containing composition to the desired cancer tissue. For example, wafers can be employed that have been impregnated with the parvovirus containing composition, e.g., parvovirus H1, wherein the wafer is attached to the edges of the resection cavity at the conclusion of surgical tumor removal. Multiple wafers can be employed in such therapeutic intervention. Cells that actively produce the parvovirus, e.g., parvovirus H1, or H1 vectors, can be injected into the tumor, or into the tumoral cavity after tumor removal.

Preferably, the parvovirus and the cytokine are administered as separate compounds. The administration of the cytokine, when administered separately, can be accomplished in a variety of ways. A preferred route of administration of the parvovirus is intratumoral administration. A preferred route of administration of the cytokine is intraperitoneal administration. The combination of both routes of administration shows synergistic effects.

The therapeutic efficacy of the combination of compounds according to the present invention can be further improved by co-administration of an immunosuppressive agent like rapamycin or cyclophosphamide.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined in the appended claims.

The present invention will be further illustrated in the following Examples which are given for illustration purposes only and are not intended to limit the invention in any way.

EXAMPLES

Example 1

Materials and Methods

(A) Cells and reagents. Human pancreatic carcinoma cell lines from primary (Panc-1, MiaPaCa-2, B×PC-3) or metastatic (Capan 1, T3M4, AsPC-1, Colo357) tumors, were obtained from ATCC (Manassas, Va.) and grown in RPMI 1640 medium supplemented with 10% fetal calf serum (FCS). The HA-RPC cell line (ATCC, LGC Standards, Wesel Germany) derived from a chemically induced pancreatic ductal adenocarcinoma in Lewis rats was grown in DMEM supplemented with 10% FCS. Human NB324K cells (ATCC, LGC Standards, Wesel Germany) used for cytotoxicity protection assays were cultured in MEM medium with 5% FCS. All media were supplemented with penicillin (100 U/ml) and streptomycin (100 μg/ml). Lyophilized recombinant rat and human IFNy were obtained from Biomol GMBH (Hamburg, Germany) and reconstituted in sterile deionized water. The mouse monoclonal antibody clone DB-1 with specificity against murine IFNγ (αIFNγ) was produced in bulk amount by NatuTec GmbH (Frankfurt, Germany). Where indicated, in some experiments cells were stimulated using LPS at final concentration of 5 μg/ml.

For the isolation of peritoneal macrophages rats received an i.p. injection of 4 ml of 4% Thioglycolate solution in PBS three days before sacrifice. After sacrificing the animals, 40 ml of sterile PBS were instilated in the peritoneal cavity and recovered using a syringe. The cells were collected by centrifugation and plated in DMEM containing 10% FCS and antibiotics.

Peripheral blood mononuclear cells (PBMC) were isolated from the heparinized blood of randomly selected healthy donors by differential centrifugation over Histopaque (Sigma) and cultured in RPMI with 10% FCS and antibiotics. Peripheral blood macrophages were enriched by adherence to plastic surface. Buffy coats were obtained from the blood bank of IKTZ Heidelberg.

(B) Virus-neutralizing antibody detection. Serial dilutions of the sera of experimental animals were made in MEM and mixed with an equal volume of H-1PV virus suspension (corresponding to 2×10⁴ pfu/well). After incubation for 30 min. at 37° C., the mixture was inoculated onto NB324K cells plated in 96-well plates (2×10³ cells/well). The cell survival rates were assessed after 72 h using a MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay.

(C) Semi-quantitative RT-PCR. For RT-PCR total RNA was extracted from pancreatic tumors or metastatic nodules of treated animals, reverse transcribed into cDNA, and PCRs for H-1PV and B-actin were performed using previously described primer sequences and conditions (Grekova S, Aprahamian M, Giese N, Schmitt S, Giese T, Falk C S, et al. Immune cells participate in the oncosuppressive activity of parvovirus H-1PV and are activated as a result of their abortive infection with this agent. Cancer Biol Ther 2011;10:1280-9).

(D) ELISA. Measurement of rat TNFγ; IL-10, IL-12 and human TNFα release was done using commercially available ELISA kits from eBioscience (Frankfurt, Germany) as described by manufacturer.

(E) FACS determination of splenocytes' proliferation index. Rat spleens were pressed against a mesh to obtain single cell suspensions and splenocytes were adjusted to a concentration of 5×10⁶/ml in PBS. The stock 5 mM CFSE solution was diluted at 1/1000 in PBS (a final concentration of 5 μM), added to lymphocytes pellet and mixed rapidly. After incubation for 5 minutes at room temperature 10 volumes of PBS containing 5% FSC were added and the cells were centrifuged. Washes in PBS/FCS were repeated 3 times. Labeled splenocytes were co-cultured with HA-RPC cells or alone as a control. After 72 h of incubation, cells were collected, washed and measured for CFSE fluorescence using FACSCalibur (BD, California, USA). The proliferation index was calculated based on the level of reduction in fluorescence intensity of the cultures.

(F) Animal studies. The orthotopic rat model using HA-RPC cells has been previously described (5). For the induction of metastasis a cell suspension was prepared in phosphate-buffered saline (PBS) out of subcutaneous tumors preformed by implantation of HA-RPC cells and injected intraperitoneally to Lewis rats at 3×10⁶ cells in 500 μl per animal.

Rat recIFNγ was injected in 3 consecutive weeks at 30 000 UI/week i.p. in a 100 μl volume for a total dose of 90 000 UI/animal. The aIFNy antibody was applied at the same times at 0.8 mg/animal for a total dose of 2.4 mg. Ascitic fluid was obtained using a peritoneal puncture under aerosol anesthesia at the time before animal sacrifice.

(G) Statistical methods. Means and standard deviations were calculated from at least three animals in triplicate wells in vitro experiments. Statistical differences were assessed using Student's t test and Wilcoxon test. For in vivo mortality data assessment, experimental groups were compared with log-rank test.

Example 2

RecIFNγ Contributes to the Immunomodulating Anticancer Effect of H-1PV

As a first step the potential impact of interferon-γ on the immunomodulating features of parvovirus H-1PV in pancreatic cancer was established. Therefore, H-1PV was applied in tumors raised orthotopically through injection of HA-RPC cells in the pancreatic tail of three groups of rats using a PBS-treated group as control. Virus treatment was also combined either with intraperitoneal recombinant rat interferon (recIFNγ) or with a neutralizing antibody against it (αIFNγ). Three days later animals were sacrificed to perform immunological profiling of splenocytes and peritoneal macrophages. The cells were cultured for 48 hours either alone (no treat), together with HA-RPC rat pancreatic cancer cells (the cell line used for initiating the tumors) or LPS. Different parameters related to the anticancer immune response, like the production of TNFα (FIG. 1A), the IL-12/IL-10 ratio (FIG. 1B) of cytokines released by macrophages, as well as the proliferation capacity of splenocytes (FIG. 1C) were analyzed. The supernatants of macrophages isolated from rats, in which H-1PV was combined with recIFNy contained up to 1 ng more TNFα, compared to those obtained from animals treated with virus only. The lowest levels of TNFα release were measured either in the non-treated mock (0.2 and 0.5 ng) or when rats were treated with a neutralizing antibody against interferon gamma (0.3 and 1 ng). A similar pattern of effects of recIFNγ and αIFNγ was detected when comparing the IL-12/IL-10 ratios of the different macrophage cultures. In addition, the combination of H-1PV with recombinant interferon gamma caused a significant twofold increase in the proliferative potential of splenocytes both spontaneously and in the presence of tumor cells.

These data pointed that H-1PV application alone can activate peritoneal macrophages or combined with recIFNy i.p. introduction could change the activation status of immune cells both in spleen and in the peritoneal cavity leading to predominance of immuno-stimulatory cytokines (TNFα, IL-12) over the immunosuppressive factors (IL-10). The decrease of the above-mentioned immunological parameters upon depletion of IFNy, especially in the case of peritoneal macrophages, confirmed our assumption that this cytokine plays a role in stimulating the innate immune system as part of the immunomodulating effect of oncolytic H-1PV.

Example 3

RecIFNγ Improves the Therapeutic Potential of H-1PV for the Treatment of PDAC Peritoneal Carcinosis

Since the results obtained were encouraging a combination of recombinant IFNγ and H-1PV parvovirus was used for the treatment of one of the most lethal complications of pancreatic cancer in humans, namely the spread of the tumor to the peritoneal cavity. To mimic this situation tumors both in the pancreas and in the peritoneal cavity of Lewis rats were induced. Two weeks later, the rats were randomly divided into four groups, in which H-1PV was applied through two different routes (intratumoral or intraperitoneal). In one group the virus i.p. inoculation was combined with recIFNγ using the same route (FIG. 2A protocol). Animal survival was followed (FIG. 2A) confirming that H-1PV intratumoral injection was still most effective to protect rats against PDAC with two animals remaining tumor free more than six months after treatment (5). H-1PV could significantly improve the survival of rats upon peritoneal application compared to the control group but was still less effective in comparison to the i.t. route. Notably, the combination with recIFNγ could significantly improve the effect of the virus extending the median survival from 83 to 96 days (FIG. 2A).

Two animals per group were sacrificed one week after treatment to analyze virus presence by RT-PCR (FIG. 2B). The distribution of viral DNA signals showed that (i) the virus could migrate from the primary tumor after intratumoral application (HIT^Tu) to metastasis (HIT^M) in the peritoneal cavity, (ii) it can infect metastasis upon intraperitoneal inoculation (HIP^M), and (iii) that upon i.p. combination with H-1PV IFNγ does not change significantly the virus levels in metastases (compare HIP^M and HIFN^M).

Isolation of peritoneal macrophages from mock, H-1PV or H-1PV with IFNγ intraperitoneally treated rats showed that the ratio between TNFα and IL-10 produced was significantly increased in the presence of recombinant IFNγ when macrophages were cocultured with HA-RPC cells, speaking in favor of phagocytes' activation (FIG. 3).

In conclusion, intratumoral application of H-1PV seems to have a superior effect compared to intraperitoneal inoculation for the treatment of PDAC. In case intraperitoneal inoculations of the virus are performed at the stage of advanced metastatic disease, a combination with IFNy can be very favorable.

Example 4

RecIFNγ Cotreatment Reduces the Titers of H-1PV Neutralizing Antibodies in Ascitic Fluid

One of the major functions of IFNy is its ability to prime the cellular (through Th1 cells/cytokines) and to down-modulate the humoral (through Th2 cells/cytokines) immune response. Therefore, it was assumed that the combination of IFNγ and oncolytic H-1PV may also reduce the titers of neutralizing antibodies produced against the virus. In order to address this hypothesis, serum from peripheral blood and ascitic fluid from the peritoneal cavity of rats participating in the above-mentioned experiment were collected and the titers of αH-1PV antibodies were determined, using a cytotoxicity protection assay on virus-sensitive cells. It was found that in the first experiment performed, no evident difference could be detected in the titer of αH-1PV in animal sera irrespective of the virus inoculation route and IFNγ treatment (FIG. 4A upper pannel). Similarly, the inoculation route had no impact on the antiviral titers in ascitic fluid collected in the time-frame (20 to 40 days) after virus treatment. On the other hand, co-application of recIFNγ together with H-1PV caused a significant reduction (from 1:5000 to 1:1280) in the titers of αH-1PV in the ascitic fluid of the animals most probably due to the stronger effect of i.p. applied IFNγ.

Then, in a modified experimental setting it was tested whether the IFNγ-provoked drop in antiviral antibodies within ascites would increase the levels of H-1PV DNA in metastases when this cytokine is applied before a second virus inoculation. First, it was noticed that the titers of αH-1PV in ascitic fluid collected within 10 to 30 days after this second H-1PV i.p. injection (FIG. 4B) were much higher than the ones induced by a single H-1PV i.p. application (FIG. 4A). This effect was most probably due to boosting of the immune system related to the repeated virus application. Interestingly, when IFNγ was applied before the second H-1PV inoculation (H−1+IFNγ) it was noticed that αH-1PV titers remained similar to the ones observed in fluids from animals subjected to a single virus inoculation (compare FIG. 4B with FIG. 4A, lower panel), suggesting that the cytokine has inhibited the overproduction of αH-1PV triggered by the second virus injection.

The H-1PV transduction level of metastasis in the two groups of rats after the second virus application (SFIG. 1) was also evaluated. Unfortunately, IFNγ treatment had no positive impact on the amounts of viral DNA in metastasis despite the reduction of antiviral antibodies (FIG. 4B) suggesting that this reduction was not sufficient to overcome the antibody pressure in ascitic fluid.

Example 5

Rec IFNγ Can Improve the Effect of H-1PV to Stimulate the Human Innate Immune System

In search of clinical relevance of the obtained data, the previous studies were continued using human PDAC cell lines and peripheral blood monocytes derived from healthy donors, aiming to find out whether the latter can be activated more efficiently with a combination of virus and IFNγ. It was previously reported that H-1PV infection leads to a limited but significant activation of human PBMCs as indicated by their TNFα release. The latter effect was largely masked in the case when PBMCs were cocultivated with pancreatic cancer cells irrespective of their infection status (Grekova S, Aprahamian M, Giese N, Schmitt S, Giese T, Falk C S, et al. Immune cells participate in the oncosuppressive activity of parvovirus H-1PV and are activated as a result of their abortive infection with this agent. Cancer Biol Ther 2011;10:1280-9). Considering that PDAC cells can express IFNγ receptors first of all the lethal effect of H-1PV and IFNγ combination on pancreatic cancer cell was evaluated. IFNγ does not change H-1PV-induced toxicity on human PDAC cells (SFIG. 2). In a next step, PBMCs were cocultured with pancreatic cancer cells that had been previously infected (or not) with H-1PV, and used the release of TNFα as a read-out for innate immune cell activation. As already previously reported, the direct infection of PBMCs with H-1PV resulted in an increased release of TNFα at 48 hpi (FIG. 5, PBMC monoculture) (Grekova S, Aprahamian M, Giese N, Schmitt S, Giese T, Falk CS, et al. Immune cells participate in the oncosuppressive activity of parvovirus H-1PV and are activated as a result of their abortive infection with this agent. Cancer Biol Ther 2011;10:1280-9). Addition of relatively low dose IFNy (50 UI/ml) to the cultures did not significantly enhance TNFα production. The same was the case when PDACs were pre-infected with H-1PV before coculturing them with the PBMCs. However, in general, in the presence of IFNγ, PBMC cocultures with Panc-1, T3M4, Capan-1 and especially Colo357 and AsPC-1 produced 100-150 pg/ml more TNFγ, corresponding to a higher level of activation of innate immune cells. Interestingly, despite the fact that the fluctuations of TNFα were not statistically significant, a tendency could be observed that PDAC cells deriving from metastatic (lymph node, liver or peritoneal) pancreatic cancer seemed to be more potent stimulators of PBMCs in the presence of IFNy than the lines established from primary PDAC tumors. In general, all these effects support the hypothesis that concomitant application of IFNy can be beneficial for the anticancer vaccination effect of H-1PV especially in the treatment of advanced metastatic disease.

Example 6

Conclusion

The observed reduction in the titers of virus neutralizing antibodies induced by IFNγ represents a very interesting phenomenon in the frame of oncolytic virotherapy. It is in agreement with the changes observed in the II-12/II-10 cytokine ratio secreted from macrophages pointing to a shift in the Th1/Th2 balance in the peritoneal cavity. Probably, an additional modification of the IFNγ treatment protocol or its combination with certain immunosuppressive agents, recently reported in oncolytic virotherapy may improve the described effect and reduce the antibodies to levels permitting repeated virus applications and metastasis transduction (Lun XQ, Jang J H, Tang N, Deng H, Head R, Bell J C, et al. Efficacy of systemically administered oncolytic vaccinia virotherapy for malignant gliomas is enhanced by combination therapy with rapamycin or cyclophosphamide. Clin Cancer Res 2009;15:2777-88).

Treatment of peripheral blood mononuclear cells with H-1PV could prime the release of TNFα, a cytokine that represents one of the main products secreted upon macrophage activation possessing also strong antitumor properties. However, coculturing PBMCs with pancreatic cancer cell lines deriving from different organ locations caused a generalized increase in TNFα levels that seemed to almost completely mask the effect of H-1PV pre-infection of PDAC cells. IFNγ could serve as an additional stimulator of TNFα production mostly in the case of cocultures between PBMCs and metastatic PDAC cancer lines. Notably, this effect was most pronounced for AsPC-1, a cell line deriving from a clinical case of peritoneal metastasis, therefore giving stronger credibility to the results obtained in animal experiments with peritoneal carcinosis. In conclusion, the combination of an oncolytic virus with a powerful imunomodulating cytokine like IFNγ may represent a promising strategy for cancer therapy. In view of the forthcoming clinical applications of H-1PV as an oncolytic agent, a therapeutic protocol involving co-treatment with the two modalities has potential to improve the outcome in terminal stage patients with pancreatic cancer.

The invention is further described by the following numbered paragraphs:

• 1. A combination of a parvovirus and a cytokine for use in treating pancreatic cancer.
• 2. The combination of compounds according to paragraph 1 for the use according to paragraph 1 characterized in that the use is for treating a terminal stage of pancreatic cancer.
• 3. The combination of compounds according to paragraph 1 for the use according to paragraph 2 characterized in that the use is for treating a terminal stage of pancreatic cancer characterized by peritoneal carcinosis.
• 4. The combination of compounds according to paragraph 1 for the use according to any one of paragraphs 1 to 3 characterized in that said cytokine is an interferon.
• 5. The combination of compounds according to paragraph 4 for the use according to any one of paragraphs 1 to 3 characterized in that said interferon is IFN-γ.
• 6. The combination of compounds according to any one of paragraphs 1 to 5 for the use according to any one of paragraphs 1 to 3 characterized in that said parvovirus is a rodent parvovirus.
• 7. The combination of compounds according to paragraph 6 for the use according to any one of paragraphs 1 to 3 characterized in that said rodent parvovirus is LuIII, Mouse minute virus (MMV), Mouse parvovirus (MPV), Rat minute virus (RMV), Rat parvovirus (RPV), Rat virus (RV) or H1 (H1-PV).
• 8. The combination of compounds according to any one of paragraphs 1 to 7 for the use according to any one of paragraphs 1 to 3 characterized in that said parvovirus is intratumorally administered and the cytokine is intraperitoneally administered.
• 9. The combination of compounds according to any one of paragraphs 1 to 7 for the use according to any one of paragraphs 1 to 8 characterized in that the combination of compounds further comprises an immunosuppressive agent.
• 10. The combination of compounds according to paragraph 9 for the use according to any one of paragraphs 1 to 8 characterized in that the immunosuppressive agent is rapamycin or cyclophosphamide.

Claims

11. A combination of a parvovirus and a cytokine for use in treating pancreatic cancer.

12. The combination of compounds according to claim 11 characterized in that the use is for treating a terminal stage of pancreatic cancer.

13. The combination of compounds according to claim 11 characterized in that the use is for treating a terminal stage of pancreatic cancer characterized by peritoneal carcinosis.

14. The combination of compounds according to claim 11 characterized in that said cytokine is an interferon.

15. The combination of compounds according to claim 14 characterized in that said interferon is IFN-γ.

16. The combination of compounds according to claim 11 characterized in that said parvovirus is a rodent parvovirus.

17. The combination of compounds according to claim 16 characterized in that said rodent parvovirus is LuIII, Mouse minute virus (MMV), Mouse parvovirus (MPV), Rat minute virus (RMV), Rat parvovirus (RPV), Rat virus (RV) or H1 (H1-PV).

18. The combination of compounds according to claim 11 characterized in that said parvovirus is intratumorally administered and the cytokine is intraperitoneally administered.

19. The combination of compounds according to claim 11 characterized in that the combination of compounds further comprises an immunosuppressive agent.

20. The combination of compounds according to claim 19 characterized in that the immunosuppressive agent is rapamycin or cyclophosphamide.

21. A method for treating pancreatic cancer comprising administering an effective amount of a combination of a parvovirus and a cytokine

22. The method according to claim 21 wherein the pancreatic cancer is a terminal stage of pancreatic cancer.

23. The method according to claim 22 wherein the terminal stage of pancreatic cancer is characterized by peritoneal carcinosis.

24. The method according to claim 21 wherein the cytokine is an interferon.

25. The method according to claim 24 wherein the interferon is IFN-γ.

26. The method according to claim 21 wherein the parvovirus is a rodent parvovirus.

27. The method according to claim 26 wherein the rodent parvovirus is LuIII, Mouse minute virus (MMV), Mouse parvovirus (MPV), Rat minute virus (RMV), Rat parvovirus (RPV), Rat virus (RV) or H1 (H1-PV).

28. The method according to claim 21 wherein the parvovirus is intratumorally administered and the cytokine is intraperitoneally administered.

29. The method according to claim 21 wherein the combination of compounds further comprises an immunosuppressive agent.

30. The method according to claim 29 wherein the immunosuppressive agent is rapamycin or cyclophosphamide.