WO2013190290A1

WO2013190290A1 - An oncolytic herpes simplex virus for use in the treatment of cancer

Info

Publication number: WO2013190290A1
Application number: PCT/GB2013/051591
Authority: WO
Inventors: Joe Conner
Original assignee: Virttu Biologics Limited
Priority date: 2012-06-20
Filing date: 2013-06-19
Publication date: 2013-12-27
Also published as: GB201210864D0; GB2503236A

Abstract

A method of selecting a subject for treatment with an oncolytic virus is disclosed, the method comprising determining in vitro the stability of an oncolytic virus in an effusion fluid sample obtained from a subject having or suspected of having a cancer, and where the oncolytic virus is stable in the effusion fluid sample selecting the subject for treatment with the oncolytic virus.

Description

AN ONCOLYTIC HERPES SIMPLEX VIRUS FOR USE IN THE TREATMENT OF

CANCER

Field of the Invention

The present invention relates to oncolytic viruses, the selection of subjects expected to respond to treatment of a cancer with an oncolytic virus and the use of oncolytic viruses in the treatment of cancer.

Background to the Invention

Oncolytic virotherapy concerns the use of lytic viruses which selectively infect and kill cancer cells. Some oncolytic viruses are promising therapies as they display exquisite selection for replication in cancer cells and their self-limiting propagation within tumors results in fewer toxic side effects. Several oncolytic viruses have shown great promise in the clinic (Bell, J., Oncolytic Viruses: An Approved Product on the Horizon? Mo!

Ther. 2010; 18(2): 233-234).

In clinical studies to date most oncolytic viruses have been administered by direct intra- tumoral injection but this limits the range of cancers that can be effectively treated to those tumors that are accessible to image-guided needles. Delivery of oncolytic viruses directly or locally to the tumor is a critical issue if an effective therapeutic dose is to be administered and not lost "off-target" or inactivated by host defence systems.

The scope for direct intra-tumoral injection is also restricted in diseases such as mesothelioma, ovarian cancer and metastatic disease where large and/or multiple tumor nodules are disseminated around a body cavity such as the pleural cavity (mesothelioma) or peritoneal cavity (mesothelioma or ovarian cancer). A clinical issue for such patients is the production of large volumes of pleural effusions or ascites which significantly impact on quality of life for patients and which require palliative treatment in the form of frequent drainage of the pleural fluid or ascites. Effusion fluids produced during tumor malignancy are commonly exudative, e.g. are composed of fluid filtered from the circulatory system (e.g. blood and/or lymph) into areas of inflammation. The composition of such fluids is variable and often complex, and may include dissolved solutes, proteins, proteoglycans, glycosaminoglycans, blood cells (white and/or red), and platelets or fragments thereof. For example, ascitic fluid may have a protein concentration of greater than 2.5g/dl. Animal models indicate that peritoneal delivery of oncolytic viruses is an effective method of controlling peritoneal disease (Coukos et al., Use of carrier cells to deliver a replication- selective Herpes Simplex virus-1 mutant for the intraperitoneal therapy of epithelial ovarian cancer. Clinical Cancer Research 1999:5; 1532-1537). One known oncolytic herpes simplex virus, HSV1716, has previously been shown to exert an oncolytic effect on malignant mesothelioma and on epithelial ovarian cancer by intraperitoneal administration of HSV1716 (Kucharczuk, J. C, et al. Cancer Res., 57/ 466-471 , 1997; Coukos et al. Clinical Cancer Research Vol.5, 1523-1537, June 1999).

Gene therapy using a replication-defective adenoviral vector expressing HSV thymidine kinase administered into the pleural cavity has been trialled in the clinic for the treatment of mesothelioma (Sterman et al., Adenovirus-Mediated Herpes Simplex Virus Thymidine Kinase/Ganciclovir Gene Therapy in Patients with Localized Malignancy: Results of a Phase I Clinical Trial in Malignant Mesothelioma. Human Gene Therapy 1999; 9: 1083- 1092).

There is a clear and fundamental distinction between oncolytic viruses and gene therapy vectors of this kind; oncolytic viruses are selectively replication-competent and will grow in actively dividing tumor cells whereas replication defective gene therapy vectors are incapable of replication in any cells. As a consequence of their self-limiting replication in tumors, oncolytic viruses are effective at low input doses whereas adenoviral gene therapy vectors require very high treatment doses to maximize delivery to as many cells as possible (typically 10⁹-10¹² pfu were used by Sterman et al.).

Loco-regional delivery into pleural or peritoneal cavities offers the potential to target large or multiple tumor nodules located therein. Moreover, the administration technique can often be added to standard patient treatment regimes following the drainage of the pleural effusions or ascites in the clinic.

An important factor in the success of such regional delivery techniques will be the stability of the oncolytic virus in the fluid present in the cavity. Owing to their pathogenesis, usually a consequence of poor lymphatic clearance, these fluids are a complex biological milieu of soluble factors derived from plasma filtrate, matrix and metabolic by-products secreted by tumor, stromal, and immune cells, and the residual debris of cells that have died. Pleural effusions have been shown to inhibit retroviral- and adenoviral-mediated gene transfer (Batra et al., Retroviral gene transfer is inhibited by chondroitin sulfate proteoglycans/ glycosaminoglycans in malignant pleural effusions. J. Biol. ChemA997; 272:11736-1 1743; Batra et al., Adenoviral Gene Transfer Is Inhibited by Soluble Factors in Malignant Pleural Effusions. Am. J. Respir. Cell Mol. Biol. (2000); 22: 613-619).

Batra et al (Batra et al., J. Biol. Chem.1997; 272: 11736-11743) reported inhibition of retroviral gene transfer in malignant pleural effusions and identified chondroitin sulfates as the inhibitory substances, which were considered to interact with the viral vector in solution rather than at the target cell surface leading to the conclusion that drainage of effusion fluid would be necessary to remove the inhibitory

proteoglycans/glycosaminoglycans before administration of the viral vector. They also advocate pre-treatment of the pleural cavity with mammalian hyaluronidase or specific chondroitinases.

Batra et al (Batra et al., Am. J. Respir. Cell Mol. Biol. (2000); 22: 613-619) reported the existence of a soluble block contained in the fluid component of malignant pleural effusions to adenovirus transduction. They also reported that binding of adenovirus to its target cell was inhibited by the presence of malignant pleural effusions, and that subsequent internalisation may also have been impaired. They propose washing the pleural cavity with saline before vector instillation as a means of enhancing adenovirus mediated gene transfer to cells.

Oncolytic viruses, with their capacity for selective propagation within tumors require much lower input doses (<1 pfu/cell) than those used for gene transfer (up to 100-1000 particles/cell in Batra et al (Am. J. Respir. Cell Mol. Biol. (2000); 22: 613-619)) but therefore are more susceptible to inhibitory factors present in pleural or peritoneal effusions than replication defective gene delivery viruses. Summary of the Invention

The present invention concerns the determination of patient sub-groups that are expected to be responsive to treatment with an oncolytic virus and, in some embodiments, the subsequent use of an oncolytic virus to treat cancer in subjects in which the oncolytic virus is stable in effusion fluid associated with the cancer. The inventors have determined that the stability of oncolytic viruses in effusion fluid associated with cancer is variable between patients having the same form of cancer. In some subjects oncolytic virus has been found to be stable in effusion fluid, whereas in effusion fluid from other subjects the same oncolytic virus has been found to be unstable, and subject to inhibition of replication. Thus, the inventors have identified the existence of two sub-groups of subject having cancer - one in which an oncolytic virus is stable in effusion fluid associated with the cancer, and one in which the oncolytic virus is not.

Accordingly, subjects in which an oncolytic virus is stable in effusion fluid associated with the cancer may respond well to treatment with the oncolytic virus, because it remains viable in the effusion fluid, allowing for viral replication and/or lysis of cancer cells (oncolysis). Thus, the inventor's findings allow for the selection of subjects having cancer that will respond well to treatment with an oncolytic virus from those that will not. As such, in one aspect of the present invention a method of selecting a subject for treatment with an oncolytic virus is provided, the method comprising determining in vitro the stability of an oncolytic virus in an effusion fluid sample obtained from a subject, where the subject preferably has or is suspected of having a cancer, and, optionally, where the oncolytic virus is stable in the effusion fluid sample, selecting the subject for treatment with the oncolytic virus.

In another aspect of the present invention a method for selecting subjects having a cancer that will respond to treatment with an oncolytic virus is provided, the method comprising performing an in vitro assay on an effusion fluid sample obtained from a subject having or suspected of having a cancer to determine the stability of an oncolytic virus in the effusion fluid sample and, optionally, where the oncolytic virus is stable in the effusion fluid sample, selecting the subject for treatment with the oncolytic virus.

Determining the stability of the oncolytic virus may comprise measuring the amount of viable virus in the effusion fluid sample and, optionally, comparing the viability of the virus in the effusion fluid sample against a control. The effusion fluid sample may be obtained from fluid surrounding and/or contacting the cancer or suspected cancer in the subject.

In another aspect of the present invention an oncolytic virus for use in a method of treating a subject having a cancer is provided, wherein the subject is characterised in that the oncolytic virus is stable in effusion fluid associated with the cancer. The method of treatment may comprise the step of determining whether the oncolytic virus is stable in effusion fluid associated with the cancer.

In another aspect of the present invention a method of treating a subject having a cancer is provided, the method comprising selecting a subject in which the oncolytic virus is stable in effusion fluid associated with the cancer, and administering the oncolytic virus to the subject, thereby treating the cancer.

In another aspect of the present invention a method for treating a cancer with an oncolytic virus is provided, the method comprising selecting a subject that has a cancer and has effusion fluid in which an oncolytic virus is stable, and administering to said subject a therapeutically effective amount of the oncolytic virus, thereby treating the cancer.

In another aspect of the present invention an oncolytic virus for use in a method of treating a cancer is provided, wherein the treatment involves selecting a subject that has a cancer and has effusion fluid in which an oncolytic virus is stable, and administering to said subject a therapeutically effective amount of the oncolytic virus.

In some embodiments of the aspects described above the subject has one of pleural effusion, peritoneal effusion (ascites) or pericardial effusion. In some preferred embodiments the patient has a malignant effusion, which may be pleural, peritoneal (ascites) or pericardial.

In embodiments of the aspects described above the oncolytic virus may be administered to a body cavity surrounding or contacting the cancer and/or may be administered to effusion fluid of the cancer. In some embodiments a fluid formulation of the oncolytic virus may be administered to a body cavity surrounding or contacting the cancer and/or to said effusion fluid. In some embodiments of the aspects described above, the virus is administered after complete or partial drainage of effusion fluid. The effusion fluid may be drained from the body cavity surrounding or contacting the cancer. The oncolytic virus may be

administered to the cavity from which the effusion fluid has been drained. In a further aspect of the present invention a kit of parts is provided, the kit comprising a container having an oncolytic virus therein, and instructions for determining the stability of the oncolytic virus in control media and in one or more effusion fluid samples. In embodiments of the aspects described above the oncolytic virus may be selected from one of: an oncolytic herpes simplex virus, an oncolytic reovirus, an oncolytic vaccinia virus, an oncolytic adenovirus, an oncolytic measles virus, an oncolytic Coxsackie virus, an oncolytic Newcastle Disease Virus, an oncolytic parvovirus, an oncolytic poxvirus, an oncolytic paramyxovirus.

Description of Preferred Embodiments

The cancer may be any unwanted cell proliferation (or any disease manifesting itself by unwanted cell proliferation), neoplasm or tumor or increased risk of or predisposition to the unwanted cell proliferation, neoplasm or tumor. The cancer may be benign or malignant and may be primary or secondary (metastatic). A neoplasm or tumor may be any abnormal growth or proliferation of cells.

In preferred embodiments the cancer is one that is associated with effusion fluid. Such association may involve production of effusion fluid by the cancerous tissue, e.g. by cancer cells, or by normal cells near to or contained in the cancerous tissue, or it may involve overproduction of effusion fluid by other tissues (e.g. the lymphatic system) as a direct or indirect response to the presence of the cancer in the subject. The cancer may be characterised by the collection of effusion fluid in one or more locations in the subject's body. Such locations may include one or more body cavities or tissue spaces. Body cavities (or serous cavities) may be formed by a serous membrane surrounding an organ or tissue and forming a sac in which fluid may collect. For example, effusion fluid may collect in one or each (right or left) pleural cavity (the space between the visceral and parietal pleura). In another example, effusion fluid may accumulate in the peritoneal cavity (the space between the parietal peritoneum and visceral peritoneum). In another example, fluid may accumulate in the pericardial cavity surrounding the heart (formed by the parietal and visceral pericardium). In another example, fluid may accumulate in the perimetrium surrounding the uterus. Thus, in some embodiments the cancer is one in which pleural effusion, peritoneal effusion (ascites), pericardial effusion or perimetrial effusion occurs.

All types of cancer may be associated with production of effusion fluid, partly because all types of cancer can metastasize to any of the body's serous cavities and result in malignant effusion (Olopade CA-A Cancer Journal For Clinicians Vol.41 , No.3 May/June 1991). Cancers in which production of effusion fluid is known to occur include cancers of the following type or tissues: lung cancers, pleural cancers, mesothelioma, malignant pleural mesothelioma, non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), ovarian cancers, ovarian carcinoma, uterine cancer, endometrial cancer, heart cancer, breast cancer, colon cancer, stomach cancer, gastric cancer, pancreatic cancer, kidney cancer, liver cancer, lymphatic cancer (e.g. lymphoma, non-Hodgkin lymphoma), soft tissue sarcoma, osteosarcoma, adenocarcinoma, parotid cancer (e.g. parotid adenocarcinoma), thymic carcinoma, cancers of the reproductive tract (including cervical, fallopian tube, endometrium), gastrointestinal tract, or genitourinary tract, leukemia, larynx, prostate, bile duct, hypernephroma, sinus piriformis carcinoma, thyroid cancer, melanoma and cancers of unknown primary (CUP) origin.

The development of a malignant pleural effusion is a common complication of advanced malignancies of many types of cancer, especially breast, lung (including NSCLC and SCLC) and ovarian carcinoma (Warren et al. European Journal of Cardio-thoracic Surgery 33 (2008) 89-94). Pleural effusions are at least known to be associated with cancers of the following type or tissue: lung, breast, lymphoma, uterus, ovarian, female reproductive tract (e.g. cervical, fallopian tube, endometrium), leukemia, pancreas, kidney, colon, stomach (gastric), mesothelioma, sarcoma, larynx, prostate, bile duct, hypernephroma, sinus piriformis carcinoma, thyroid cancer, non-Hodgkin lymphoma, malignant melanoma, reproductive tract, gastrointestinal tract, genitourinary tract, (Warren et al. Ann Thorac Surg 2008;85: 1049-55; Warren et al. European Journal of Cardio-thoracic Surgery 33 (2008) 89-94; Schulze et al. Ann Thorac Surg 2001 ;71 : 1809- 12; Olopade CA-A Cancer Journal For Clinicians Vol.41 , No.3 May/June 1991).

Peritoneal effusions (ascites) are at least known to be associated with cancers of the following type or tissue: ovarian, epithelial related ovarian, uterus, breast, colon, gastric, pancreatic, hepatic, colon, lymphoma, mesothelioma, and cancers of unknown primary (CUP) origin (Olopade CA-A Cancer Journal For Clinicians Vol.41 , No.3 May/June 1991) Pericardial effusions are at least known to be associated with cancers of the following type or tissue: lung, breast, leukemia, lymphoma, sarcoma, melanoma (Olopade CA-A Cancer Journal For Clinicians Vol.41 , No.3 May/June 1991). Effusion fluid refers to an excess of fluid produced by a subject in direct or indirect response to the presence of a cancer in the subject. In preferred embodiments the effusion fluid collects in a body cavity such that accumulation of effusion fluid may occur where the rate of production of the effusion fluid exceeds the rate of reabsorption. Pleural effusions (sometimes called malignant pleural effusions) lead to accumulation of fluid in the pleural cavity and occur in some lung cancers, e.g. mesothelioma. Effusion fluid collecting in the peritoneal cavity is commonly referred to as ascites, and can be a symptom of a number of types of cancer including cancer of the breast, lung, colon, stomach, pancreas, ovary, endometrium as well as lymphoma. Pericardial effusion is the abnormal accumulation of fluid in the pericardial cavity. The effusion fluid is preferably exudative.

Effusion fluid can be drained from a respective body cavity by well-known aseptic procedures (e.g. see Warren et al. Ann Thorac Surg 2008;85:1049-55; Warren et al. European Journal of Cardio-thoracic Surgery 33 (2008) 89-94). In some instances, a tube or catheter is inserted in the body cavity in order to drain effusion fluid. Drainage of effusion fluid is a common part of the diagnosis, treatment and management of many forms of cancer. Drainage of effusion fluid provides a means of obtaining a sample of a subject's effusion fluid for diagnostic analysis and for determination of stability of an oncolytic virus according to the present invention.

Treatment with oncolytic virus may involve administration of the virus to a body cavity in which effusion fluid is accumulating in the subject (intracavitary administration, e.g.

intrapleural or intraperitoneal); for example, as described in (Kelly et al. Novel Oncolytic Agent GLV-1h68 Is Effective Against Malignant Pleural Mesothelioma. Human Gene Therapy 19:744-782 (August 2008)). Such administration may involve administration via an existing drain or catheter inserted in the patient for the purpose of draining effusion fluid. The virus may be administered as a fluid formulation. Administration of virus may follow complete or partial drainage of effusion fluid from the body cavity. Administration to the body cavity permits the oncolytic virus to be dispersed throughout the body cavity. Some aspects of the present invention involve determining the stability of an oncolytic virus in an effusion fluid sample obtained from a subject. Viral stability refers to the continuing ability of viral particles to replicate and thereby maintain a significant population of replication-competent virus. The present invention is based on the observation that the number of replication-competent viruses decreases rapidly over time when the virus is maintained in effusion fluid samples from some patients, whilst in effusion fluid samples from other patients the number of replication-competent viruses is maintained at higher levels for longer. This finding indicates that in some patients components of the effusion fluid inhibit (directly or indirectly) the ability of the virus to replicate and maintain a high concentration of viral particles. Thus, measuring the number/concentration of replication-competent viral particles present in an effusion fluid sample at a given point in time provides an indicator of whether and to what extent the virus will be replication competent when in contact with effusion fluid in the patient, which provides an indirect measure of the therapeutic benefit that the patient is expected to derive from the virus treatment.

Stability of the virus can be determined by measuring the amount of viable viral particles (e.g. intact and/or replication-competent viral particles) in the effusion fluid sample over time. Such determination may be carried out by in vitro assay, in which oncolytic virus is added to the effusion fluid sample and aliquots are tested for viral viability at selected time intervals to determine the presence and/or amount of viable virus.

An oncolytic virus may be considered stable where the viral titre (the number of replication competent viral particles) remains stable over time (preferably over one of at least ten minutes, twenty minutes, thirty minutes, at least one hour, at least two hours, at least three hours, at least four hours, at least five hours, at least six hours, at least seven hours, at least eight hours, at least nine hours, or at least ten hours). Under in vitro conditions many viruses will exhibit a natural instability over time. For example, at room temperature HSV1716 is stable in vitro for about 2 hours, after which the viral titre begins to decrease. Accordingly, the time period in which the viral stability in test samples is determined may also have a maximum that reflects the normal stability of the virus in control conditions in vitro. This may be one of no more than 12 hours, no more than 10 hours, no more than 8 hours, no more than 6 hours, no more than 4 hours, no more than 2 hours, no more than 1 hour, or no more than 30 minutes. The inventors have determined experimentally that the inhibition effect of effusion fluid on the ability of a virus to replicate can be rapid, with incubation of virus in effusion fluid for as little as 10 minutes leading to greater than a 50% loss in viral titre in some cases. Therefore, in some embodiments analysis of viral titre should be conducted following a short incubation in effusion fluid, e.g. of about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 40 minutes, about 50 minutes, or about 60 minutes.

Thus, depending on the type of virus being analysed and the known stability

characteristics of that virus in control conditions in vitro a time window can be determined in which analysis of viral titre in the effusion fluid sample(s) and in control sample(s) should be determined. Suitable time windows include one or more of: from 1 minute to 30 minutes, from 10 minutes to 30 minutes, from 10 minutes to 1 hour, from 1 minute to 1 hour, from 1 minute to 2 hours, from 30 minutes to 1 hour, from 30 minutes to 2 hours, from 1 hour to 2 hours, from 1 hour to 4 hours, from 2 hours to 4 hours, from 2 hours to 6 hours, from 4 hours to 6 hours, from 4 hours to 8 hours, from 6 hours to 8 hours, from 6 hours to 10 hours, from 8 hours to 10 hours, from 8 hours to 12 hours.

In some embodiments an oncolytic virus is considered to remain stable over time if the viral titre after incubation in the effusion fluid sample for the selected time period is greater than 50% (or one of 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In other embodiments an oncolytic virus is considered to remain stable over time if the viral titre after incubation in the effusion fluid sample for the selected time period is greater than 1 % (or one or 3%, 5%, 10%, 15%, or 20%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of between 10 minutes and one hour is greater than 1 % (or one of or 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period. In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of between 10 minutes and one hour is greater than 10% (or one of or 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period. In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of between 10 minutes and 30 minutes is greater than 10% (or one of or 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of between 30 minutes and one hour is greater than 5% (or one of or 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of at least one hour is greater than 0.1% (or one of or 0.5%, 1 %, 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be stable in the effusion fluid sample if the viral titre after incubation in the effusion fluid sample for a period of at least two hours is greater than 0.01 % (or one of or 0.05%, 0.1%, 0.5%, 1%, 3%, 5%, 10%,

15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be unstable in the test sample if the viral titre after incubation in the effusion fluid sample for a period of between 10 minutes and one hour is less than 1 % (or one of or 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period. In some embodiments, an oncolytic virus is considered to be unstable in the test sample if the viral titre after incubation in the effusion fluid sample for a period of between 30 minutes and one hour is less than 1 % (or one of or 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period. In some embodiments, an oncolytic virus is considered to be unstable in the test sample if the viral titre after incubation in the effusion fluid sample for a period of at least one hour is less than 0.1 % (or one of or 0.5%, 1%, 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, an oncolytic virus is considered to be unstable in the test sample if the viral titre after incubation in the effusion fluid sample for a period of between 10 minutes and two hours is less than 0.01 % (or one of or 0.02%, 0.03%, 0.04%, 0.05%, 0.1 %, 0.5%, 1 %, 3%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period.

In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 10 minutes that is greater than 20% (or one of 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 %, 5% or 10% of the viral titre at the start of the incubation period.

In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 20 minutes that is greater than 20% (or one of 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 %, 5% or 10% of the viral titre at the start of the incubation period.

In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 30 minutes that is greater than 20% (or one of 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%) of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 %, 5% or 10% of the viral titre at the start of the incubation period. In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 10 minutes that is greater than 30% of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 %, or 5% of the viral titre at the start of the incubation period.

In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 20 minutes that is greater than 30% of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 % or 5% of the viral titre at the start of the incubation period.

In some embodiments, a stable oncolytic virus is one which exhibits a viral titre after incubation in the effusion fluid sample for a period of 30 minutes that is greater 30% of the viral titre at the start of the incubation period, and exhibits a viral titre after incubation in the effusion fluid sample for a period of 60 minutes that is greater than 1 % or 5% of the viral titre at the start of the incubation period. A number of methods for determining the ability of a virus to replicate are known to those of ordinary skill in the art.

For example, viral titration methods are well known. One suitable titration method for herpes simplex virus is described in MacLean et al Journal of General Virology (1991) 72, 631-639. Another is described in Kelly et al. Human Gene Therapy 19:744-782 (August 2008).

More generally, viral titration involves serial dilution of a viral stock or virus containing sample, e.g. to produce a series of dilutions each containing one order of magnitude less virus (e.g. 10^"1, 10^"2 ... 10^"8). A standard amount, e.g. 0.1 ml, of each dilution is then added to cells in culture, e.g. a monolayer of BHK or Vero cells. The cellular monolayer is then overlaid with a high viscosity medium. The cells are then incubated, e.g. for about 48 or 72 hours. The high viscosity medium is then removed and the cells are stained, e.g. using 0.5% (w/v) crystal violet. Where the virus has replicated a hole is present in the monolayer which is not stained (called a plaque). The plaques can be counted and by taking account of the dilution the concentration of virus in the initial stock/sample can be determined.

Preferably such methods will be carried out at room temperature.

Stability of an oncolytic virus in a selected effusion fluid sample may be further determined by comparison with stability of the oncolytic virus in a control medium, e.g. saline, phosphate buffered saline, or compound sodium lactate with 10% glycerol. A virus may be considered stable in the effusion fluid if the viral titre is the same as, greater than, or no more than 50% less than (preferably no more than one of 40%, 30%, 20%, 10%, 5%. 4%, 3%, 2% or 1 % less than) the viral titre of the virus when incubated in the control medium for the same period of time (adjusting for any difference in the initial viral titre with which the effusion fluid sample and control medium are inoculated or assuming the initial viral titre inoculated into the effusion fluid sample and control media are the same or approximately the same e.g. within a multiple of 1 , 2, 3, 4 or 5 times).

Comparison against control data may involve performing a control experiment in conjunction with the test experiment. Alternatively, the control experiment may have been performed previously and the comparison may be made against a data set or curve produced for the control experiment.

Where a virus is determined to be stable in a patient effusion fluid sample such that the replication-competent viral population does not decrease rapidly towards zero, but is maintained over time, e.g. over 1 , 2, 3, 4, 5 or 6 hours, either at or near control levels or otherwise at significant non-zero levels the subject from which the sample was obtained may be selected for treatment with the oncolytic virus.

Some methods according to the present invention may be considered methods of diagnosis in that they may diagnose characteristics of a cancer that allow for differential treatment. The diagnostic outcome of the in vitro testing of patient effusion fluid samples may be that a cancer is suitable, or not suitable, for treatment with a particular oncolytic virus. The suitability of the cancer for treatment may reflect the expectation that the oncolytic virus will remain replication-competent over time (e.g. over 1 , 2, 3, 4, 5, 6 or more hours) when in contact with effusion fluid in the patient. In some aspects of the present invention a kit of parts is provided. In some embodiments the kit may have one or more (e.g. 2, 3, 4 or 5) containers each having a predetermined quantity of oncolytic virus, e.g. predetermined number/quantity/concentration of viral particles, enabling a plurality of assays to be performed on one or more effusion samples and optionally one or more control assays. In some embodiments the virus is provided in fluid or lyophilised form. In some embodiments the kit further comprises a data set or curve for a previously conducted control experiment which may be compared with data obtained from effusion fluid samples tested with the oncolytic virus. The data set or curve may be provided in electronic form, e.g. on a data carrier which may be provided with the kit or on a website from which the data set or curve may be accessed and/or downloaded where information about the website may be provided with the kit.

In some embodiments the kit may also contain apparatus suitable to obtain an effusion fluid sample from a subject, including one or more of a catheter or drain tube, needle, and container to collect effusion fluid drained from the subject, such apparatus preferably being provided in sterile form.

Methods according to the present invention may be performed in vitro or in vivo. The term "in vitro" is intended to encompass experiments with materials, biological substances, body fluids, cells and/or tissues in laboratory conditions or in culture whereas the term "in vivo" is intended to encompass experiments and procedures with intact multi-cellular organisms.

The subject to be treated may be any animal or human. The subject is preferably mammalian, more preferably human. The subject may be a non-human mammal, but is more preferably human. The subject may be male or female. The subject may be a patient. A subject may have been diagnosed with a cancer, or be suspected of having a cancer prior to diagnosis. The subject may exhibit one of pleural effusion, peritoneal effusion (ascites) or pericardial effusion.

The oncolytic virus may be any oncolytic virus. Preferably it is a replication-competent virus, being replication-competent at least in the target tumor cells. In some

embodiments the oncolytic virus is selected from one of an oncolytic herpes simplex virus, an oncolytic reovirus, an oncolytic vaccinia virus, an oncolytic adenovirus, an oncolytic Newcastle Disease Virus, an oncolytic Coxsackie virus, an oncolytic measles virus. An oncolytic virus is a virus that will lyse cancer cells (oncolysis), preferably in a selective manner. Viruses that selectively replicate in dividing cells over non-dividing cells are often oncolytic. Oncolytic viruses are well known in the art and are reviewed in Molecular Therapy Vol.18 No.2 Feb 2010 pg 233-234. In some embodiments the oncolytic virus is a herpes simplex virus. The herpes simplex virus (HSV) genome comprises two covalently linked segments, designated long (L) and short (S). Each segment contains a unique sequence flanked by a pair of inverted terminal repeat sequences. The long repeat (RL or R_L) and the short repeat (RS or R_s) are distinct.

The HSV ICP34.5 (also called γ34.5) gene, which has been extensively studied, has been sequenced in HSV-1 strains F and syn17+ and in HSV-2 strain HG52. One copy of the ICP34.5 gene is located within each of the RL repeat regions. Mutants inactivating one or both copies of the ICP34.5 gene are known to lack neurovirulence, i.e. be avirulent non-neurovirulent (non-neurovirulence is defined by the ability to introduce a high titre of virus (approx 10⁶ plaque forming units (pfu)) to an animal or patient without causing a lethal encephalitis such that the LD₅₀ in animals, e.g. mice, or human patients is in the approximate range of >10⁶ pfu), and be oncolytic. Oncolytic HSV that may be used in the present invention include HSV in which one or both of the γ34.5 (also called ICP34.5) genes are modified (e.g. by mutation which may be a deletion, insertion, addition or substitution) such that the respective gene is incapable of expressing, e.g. encoding, a functional ICP34.5 protein. Preferably, in HSV according to the invention both copies of the γ34.5 gene are modified such that the modified HSV is not capable of expressing, e.g. producing, a functional ICP34.5 protein.

In some embodiments the oncolytic herpes simplex virus may be an ICP34.5 null mutant where all copies of the ICP34.5 gene present in the herpes simplex virus genome (two copies are normally present) are disrupted such that the herpes simplex virus is incapable of producing a functional ICP34.5 gene product. In other embodiments the oncolytic herpes simplex virus may lack at least one expressible ICP34.5 gene. In some embodiments the herpes simplex virus may lack only one expressible ICP34.5 gene. In other embodiments the herpes simplex virus may lack both expressible ICP34.5 genes. In still other embodiments each ICP34.5 gene present in the herpes simplex virus may not be expressible. Lack of an expressible ICP34.5 gene means, for example, that expression of the ICP34.5 gene does not result in a functional ICP34.5 gene product. Oncolytic herpes simplex virus may be derived from any HSV including any laboratory strain or clinical isolate (non-laboratory strain) of HSV. In some preferred embodiments the HSV is a mutant of HSV-1 or HSV-2. Alternatively the HSV may be an intertypic recombinant of HSV-1 and HSV-2. The mutant may be of one of laboratory strains HSV-1 strain 17, HSV-1 strain F or HSV-2 strain HG52. The mutant may be of the non- laboratory strain JS-1. Preferably the mutant is a mutant of HSV-1 strain 17. The herpes simplex virus may be one of HSV-1 strain 17 mutant 1716, HSV-1 strain F mutant R3616, HSV-1 strain F mutant G207, HSV-1 mutant NV1020, or a further mutant thereof in which the HSV genome contains additional mutations and/or one or more heterologous nucleotide sequences. Additional mutations may include disabling mutations, which may affect the virulence of the virus or its ability to replicate. For example, mutations may be made in any one or more of ICP6, ICPO, ICP4, ICP27. Preferably, a mutation in one of these genes (optionally in both copies of the gene where appropriate) leads to an inability (or reduction of the ability) of the HSV to express the corresponding functional polypeptide. By way of example, the additional mutation of the HSV genome may be accomplished by addition, deletion, insertion or substitution of nucleotides.

A number of oncolytic herpes simplex viruses are known in the art. Examples include HSV1716, R3616 (e.g. see Chou & Roizman, Proc. Natl. Acad. Sci. Vol.89, pp.3266- 3270, April 1992), G207 (Toda et al, Human Gene Therapy 9:2177-2185, October 10, 1995), NV1020 (Geevarghese et al, Human Gene Therapy 2010 Sep; 21 (9):1119-28), RE6 (Thompson et al, Virology 131 , 171-179 (1983)), and Oncovex™ (Simpson et al, Cancer Res 2006; 66:(9) 4835-4842 May 1 , 2006; Liu et al, Gene Therapy (2003): 10, 292-303), dlsptk, hrR3,R4009, MGH-1 , MGH-2, G47A, Myb34.5, DF3y34.5, HF10,

NV1042, RAMBO, rQNestin34.5, R5111 , R-LM113, CEAICP4, CEAy34.5, DF3v34.5, KeM34.5 (Manservigi et al, The Open Virology Journal 2010; 4:123-156), rRp450, M032 (Campadelli-Fiume et al, Rev Med. Virol 2011 ; 21 :213-226), Bacol (Fu et al, Int. J.

Cancer 2011 ; 129(6): 1503- 10) and M032 and C134 (Cassady et al, The Open Virology Journal 2010; 4: 103-108).

In some preferred embodiments the herpes simplex virus is HSV-1 strain 17 mutant 1716 (HSV1716). HSV 1716 is an oncolytic, non-neurovirulent HSV and is described in EP 0571410, WO 92/13943, Brown et al (Journal of General Virology (1994), 75, 2367-2377) and MacLean et al (Journal of General Virology (1991), 72, 631-639). HSV 1716 has been deposited on 28 January 1992 at the European Collection of Animal Cell Cultures, Vaccine Research and Production Laboratories, Public Health Laboratory Services, Porton Down, Salisbury, Wiltshire, SP4 OJG, United Kingdom under accession number V92012803 in accordance with the provisions of the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure (herein referred to as the 'Budapest Treaty').

Other types of oncolytic virus are also known in the art. These include oncolytic poxvirus (e.g. orthopoxviruses) such as vaccinia virus JX-954 and GLV-1 h68 (Park, BH et al. (2008) Lancet Oncol 9:533-542; Kelly et al. Human Gene Therapy 19:744-782 (August 2008); Wennier et al. Expert Rev Mol Med. 13 e18 5 Dec 2011) oncolytic reovirus such as oncolytic reovirus type 3 Dearing (Pandha, HS, et al. (2009) Clin Cancer Res 15:6158- 6166; Vidal, L et al. (2008) Clin Cancer Res 14:7127-7137), oncolytic adenovirus such as Onyx-015 (Cohen and Rudin. Curr Opin Investig Drugs 2001 Dec;2(12):1770-5), oncolytic paramyxovirus such as oncolytic measles virus MV-Edm (Nakamura, T, et al. (2005) Nat Biotechnol 23: 209-214; Wennier et al. Expert Rev Mol Med. 13 e18 5 Dec 2011), oncolytic Coxsackie virus such as A13, A15, A18, A21 (Au et al, Virology Journal 2011 , 8:22), oncolytic Newcastle Disease Virus (Mansour et al, J Virol 2011 , Jun; 85(12):6015- 23), and oncolytic parvoviruses such as H-1 PV and MVM (Wennier et al. Expert Rev Mol Med. 13 e18 5 Dec 2011).

In some embodiments the genome of an oncolytic virus according to the present invention may be further modified to contain nucleic acid encoding at least one copy of a polypeptide that is heterologous to the virus (i.e. is not normally found in wild type virus) such that the polypeptide can be expressed from the nucleic acid. As such, the oncolytic virus may also be an expression vector from which the polypeptide may be expressed. Examples of such viruses are described in WO2005/049846 and WO2005/049845.

In order to effect expression of the polypeptide, nucleic acid encoding the polypeptide is preferably operably linked to a regulatory sequence, e.g. a promoter, capable of effecting transcription of the nucleic acid encoding the polypeptide. A regulatory sequence (e.g. promoter) that is operably linked to a nucleotide sequence may be located adjacent to that sequence or in close proximity such that the regulatory sequence can effect and/or control expression of a product of the nucleotide sequence. The encoded product of the nucleotide sequence may therefore be expressible from that regulatory sequence. Oncolytic viruses may be formulated as medicaments and pharmaceutical compositions for clinical use and in such formulations may be combined with a pharmaceutically acceptable carrier, diluent or adjuvant. The composition may be formulated for topical, parenteral, systemic, intracavitary, intravenous, intra-arterial, intramuscular, intrathecal, intraocular, intratumoral, subcutaneous, oral or transdermal routes of administration which may include injection. Suitable formulations may comprise the virus in a sterile or isotonic medium. Medicaments and pharmaceutical compositions may be formulated in fluid (including gel) or solid (e.g. tablet) form. Fluid formulations may be formulated for administration by injection or via catheter to a selected region of the human or animal body.

Administration is preferably in a "therapeutically effective amount", this being sufficient to show benefit to the individual. The actual amount administered, and rate and time-course of administration, will depend on the nature and severity of the disease being treated. Prescription of treatment, e.g. decisions on dosage etc, is within the responsibility of general practitioners and other medical doctors, and typically takes account of the disorder to be treated, the condition of the individual patient, the site of delivery, the method of administration and other factors known to practitioners. Examples of the techniques and protocols mentioned above can be found in Remington's Pharmaceutical Sciences, 20th Edition, 2000, pub. Lippincott, Williams & Wilkins.

Targeting therapies may be used to deliver the oncolytic virus to certain types of cell, e.g. by the use of targeting systems such as antibody or cell specific ligands. Targeting may be desirable for a variety of reasons; for example if the virus is unacceptably toxic in high dose, or if it would otherwise require too high a dosage, or if it would not otherwise be able to enter the target cells.

HSV capable of targeting cells and tissues are described in (PCT/GB2003/000603; WO 03/068809), hereby incorporated in its entirety by reference.

An oncolytic virus may be administered alone or in combination with other treatments, either simultaneously or sequentially dependent upon the condition to be treated. Such other treatments may include chemotherapy (including either systemic treatment with a chemotherapeutic agent or targeted therapy using small molecule or biological molecule (e.g. antibody) based agents that target key pathways in tumor development, maintenance or progression) or radiotherapy provided to the subject as a standard of care for treatment of the cancer.

The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. Aspects and embodiments of the present invention will now be illustrated, by way of example, with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference. Brief Description of the Figures

Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which: Figure 1. Graphical representation of the stability of 2x10^s pfu HSV1716 in PE 1-5 and 0.9% saline.

Figure 2. (A) Graphical representation of titres presented in Table 2a, (B) Graphical representation of titres presented in Table 2b, (C) Graphical representation of the stability of 1x10⁷ pfu HSV1716 in PE 1-5 and 0.9% saline.

Figure 3. (A) Table showing titration counts for stability of HSV1716 in saline vs 5 different pleural effusion samples. (B) Table showing titration counts for stability of HSV1716 in saline vs 5 different pleural effusion samples. Duplicate samples were analysed.

Figure 4. Chart showing percentage virus detectable by titration after incubation of 4x10⁷ pfu HSV1716 with 10 representative ovarian ascites samples. Detailed Description of the Invention The details of one or more embodiments of the invention are set forth in the

accompanying description below including specific details of the best mode contemplated by the inventors for carrying out the invention, by way of example. It will be apparent to one skilled in the art that the present invention may be practiced without limitation to these specific details.

Examples

Example 1

Samples

Pleural effusion samples were collected from 5 different patients having malignant pleural mesothelioma at Cancer Clinical Trials Centre, Weston Park Hospital, Sheffield, United Kingdom under standard procedures and stored at -20°C prior to shipping to Virttu Biologies, Glasgow, United Kingdom on dry-ice. On arrival, the 5 pleural effusion samples (designated PE 1-5) were thawed, divided into 5ml aliquots and then re-frozen at -70°C until required.

1) Stability of HSV1716 in saline vs. PE 1 -5 ln-house GMP-like HSV1716 (2x10^s pfu) was added to 5ml 0.9% saline or 5ml PE 1-5 previously incubated at 37°C in a water bath. The solutions were removed from the water bath, virus was added and, after vortexing, were left at room temperature (20°C). Aliquots were removed at 0, 5mins, 10mins, 20mins, 40mins, 60mins and 120mins for immediate titration and results are presented graphically in Figure 1.

Titres for samples 1-3 and for saline are reported in Table 1a, and for samples 4 and 5 and for saline in Table 1 b. Plaque counts information is provided in Figure 3.

Table 1a

Sample 1 Sample 2 Sample 3 Saline

Time (mins) Titre (pfu/ml) Titre (pfu/ml) Titre (pfu/ml) Titre (pfu/ml)

0 1.39x10⁶ 5.0x10⁴ 1.81x10^s 4.10x10^s

5 1.18x10⁶ 350 1.80x10^s 5.70x10^s

10 9.7x10⁵ 0 2.03x10^s 4.80x10^b

20 5.7x10^b 0 1.78x10^s 2.70x10^s 40 3.7x10⁴ 0 1.70x10^s 3.90x10^s

60 80 0 1.51x10^s 3.79x10^s

120 30 0 1.79x10^s 3.10x10^b

Table 1 b

2) Stability of HSV1716 in saline vs. PE 1-5.

In-house GMP-like HSV1716 (1x10⁷ pfu) was added to 5ml 0.9% saline or 5ml PE1-5 in duplicate at 37°C as described in Section 1) above. Solutions were then left at room temperature (20°C) and aliquots removed at time 0, 5mins, 10mins, 15mins, 20mins, 40mins, 60mins, 90mins and 120mins for immediate titration. Tables 2a and 2b provide the titres for each of the duplicates with the individual results shown graphically in Figures 2a and 2b. The average titres from the duplicate samples are presented graphically in Figure 2c.

Table 2a

Sample Sample Sample Sample Sample Sample

1/1 1/2 2/1 2/2 3/1 3/2

Time Titre Titre Titre Titre Titre Titre (mins) (pfu/ml) (pfu/ml) (pfu/ml) (pfu/ml) (pfu/ml) (pfu/ml)

0 1.35x10⁷ 1.25x10⁷ 4.7x10⁴ 4.2x10⁴ 1.31x10⁷ 1.28x10⁷

5 1.08x10' 1.04x10' 40 40 1.1 1x10' 1.32x10'

10 7.6x10 8.8x10 40 20 1.19x10' 1.11x10'

15 3.7x10^B 4.4x10 10 10 1.07x10' 1.16x10' 20 1.99X10⁶ 2.16X10⁶ 10 0 1.29x10⁷ 1.32x10⁷

40 3.8x10⁵ 4.1x10⁵ 0 0 1.26x10⁷ 1.17x10⁷

60 5.8x10⁴ 7.1x10⁴ 0 0 1.28x10' 9.6x10⁶

90 5500 4100 0 0 7.5x10^B 8x10⁶

120 1800 2000 0 0 5.3x10^B 6.2x1 O^e

Table 2b

3) Properties of PE1 -5

The results presented above in Sections 1 and 2 suggest considerable differences in HSV1716 stability in PEs 1-5 and consequently, their pH and protein concentrations were compared for possible differences.

Table 3 - Appearance, pH and protein content of PEs 1-5

Protein concentration was determined by the Bradford method using BioRad's Protein Assay Dye Reagent and bovine serum albumin as standard.

Discussion HSV1716 was found to be stable in 0.9% saline during two hour incubation at room temperature (e.g. see Figures 1 and 2A-C).

Pleural effusion fluids from different patients were found to have variable effects on HSV1716 stability.

HSV1716 was found to be very stable in PE3 with no loss of titre during 2 hours incubation at room temp.

Compared to PE3 and 0.9% saline, HSV1716 titres decreased over time during incubation in PE1 with ~50% virus still detectable after 10 mins, ~5% remaining after 1 hour and only ~0.02% remaining after 2 hours.

HSV1716 was found to be highly unstable in PE2, PE4 and PE5 with rapid loss of all virus infectivity within 20-40 minutes. Little physical variation in pleural fluid properties amongst the 5 pleural effusion samples was identified.

The data presented here for oncolytic HSV1716 demonstrates that (unlike the previously reported study by Batra et al (Am. J. Respir. Cell Mol. Biol. (2000); 22: 613-619) for adenoviral gene therapy vectors in which there was inhibition of transduction by all pleural effusates tested) there was a marked differential response across the patient samples.

This provided the basis for testing effusion fluid from individual patients to determine the stability of an oncolytic viral therapeutic on a patient by patient basis, thereby providing a method of selecting patients suitable for treatment with the oncolytic virus. Such methods would not require the drawing of any additional patient samples other than those already collected in standard treatment for the disease. Example 2 - Titration interference in ovarian ascites

Titration interference was tested in 10 representative ascites fluid samples from women with ovarian cancer: 5 from platinum-resistant ovarian cancer ascites and 5 from platinum-sensitive ovarian cancer ascites.

Titration interference by the ovarian ascites was assessed by aliquoting 4ml of each ascites fluid into a bijou and spiking with 1 ml of HSV1716 at 4x10⁷ pfu/ml. The expected titre of the spiked sample will be 8x10⁶ pfu/ml. As a control 4ml of PBS were spiked with 4x10⁷ pfu HSV1716. Samples were incubated at 20°C for 15 minutes and then titrated in Vero cells.

Results are presented in Table 4, and are represented graphically in Figure 4.

A very broad spectrum of titration interference was obtained with the 10 representative ovarian ascites fluids ranging from almost complete neutralization of HSV1716 to only 25% neutralisation. Sample OA07 was the most potent, neutralizing 99.992% of the spiked virus with samples OA10 and OA06 also having potent neutralizing effects (>99% of spiked virus neutralized). Samples OA01 , OA02, OA04 and OA09 had a strong neutralizing effect with >90% of the spiked HSV1716 neutralised. Neutralisation was least potent in samples OA03 (85% neutralization) and OA08 (72% neutralization) and, in particular, in sample OA05 there was only 25% of the spiked virus neutralized. The samples are from both platinum-sensitive and platinum-resistant patients and Table 5 presents the results with respect to the platinum sensitivity of the 10 ovarian ascites fluids. Although there is no definitive correlation between neutralization capacity for HSV1716 and platinum sensitivity, there is a trend for the ovarian ascites with the greater neutralization capacity to be from platinum-sensitive patients with 4/5 having > 90% neutralization capacities compared to 3/5 for the platinum-resistant ovarian ascites. The most potent neutralizing ovarian ascites (OA07) was in the platinum-sensitive group and the least potent was in the platinum resistant (OA05).

Table 4. Plaque counts from titration of spiked ovarian ascites samples from 10 different patients. Expected titre was 8x10⁶ pfu/ml.

Dilution Titre % PBS

10 ' 10^"" 10^"-* 10^"4 (pfu/ml) control

OA01 13 130000 2.031

OA02 13 130000 2.031

OA03 98 980000 15.313

OA04 24 240000 3.750

OA05 48 4800000 75.000

OA06 19 19000 0.297

OA07 5 500 0.008

OA08 179 1790000 27.969

OA09 47 470000 7.344

OA10 16 16000 0.250

PBS 64 6400000 100.000

Table 5. Neutralisation capacity of representative ovarian ascites from platinum-resistant and platinum-sensitive patients. +++++ = highly potent neutralisation (>99.9% of input virus neutralised), ++++ =potent neutralisation (>99%), +++ =strong neutralisation (>90%), ++ = moderate neutralisation (>50%) and + = weak neutralisation (>20%).

Platinum-sensitive Neutralisation Platinum-resistant Neutralisation effect effect

OA04 +++ OA01 +++

OA02 +++ OA08 ++

OA07 +++++ OA09 +++

OA06 ++++ OA05 +

OA03 ++ OA10 ++++

Claims

Claims:

1. A method of selecting a subject for treatment with an oncolytic herpes simplex virus, the method comprising:

determining in vitro the stability of an oncolytic herpes simplex virus in an effusion fluid sample obtained from a subject having or suspected of having a cancer, and

where the oncolytic herpes simplex virus is stable in the effusion fluid sample selecting the subject for treatment with the oncolytic herpes simplex virus.

2. The method of claim 1 , wherein determining stability of the oncolytic herpes simplex virus comprises measuring the amount of viable virus in the effusion fluid sample and, optionally, comparing the viability of the virus in the effusion fluid sample against a control.

3. The method of claim 1 or 2, wherein the effusion fluid sample is obtained from fluid surrounding and/or contacting the cancer or suspected cancer in the subject.

4. The method of any one of claims 1 to 3, wherein the subject has one of pleural effusion, peritoneal effusion (ascites) or pericardial effusion.

5. An oncolytic herpes simplex virus for use in a method of treating a subject having a cancer, wherein the subject is characterised in that the oncolytic herpes simplex virus is stable in effusion fluid associated with the cancer.

6. An oncolytic herpes simplex virus for use in a method of treating a subject having a cancer according to claim 5, wherein the subject has one of pleural effusion, peritoneal effusion (ascites) or pericardial effusion.

7. An oncolytic herpes simplex virus for use in a method of treating a subject having a cancer according to claim 5 or 6, wherein the oncolytic herpes simplex virus is administered to a body cavity surrounding or contacting the cancer.

8. An oncolytic herpes simplex virus for use in a method of treating a subject having a cancer according to any one of claims 5 to 7, wherein the oncolytic herpes simplex virus is administered to effusion fluid associated with the cancer.

9. An oncolytic herpes simplex virus for use in a method of treating a subject having a cancer according to any one of claims 5 to 8, wherein a fluid formulation of the oncolytic herpes simplex virus is administered to a body cavity surrounding or contacting the cancer and/or to said effusion fluid.

10. A method of treating a subject having a cancer, the method comprising selecting a subject in which an oncolytic herpes simplex virus is stable in effusion fluid associated with the cancer, and administering the oncolytic herpes simplex virus to the subject, thereby treating the cancer.

11. The method of claim 10, wherein the subject has one of pleural effusion, peritoneal effusion (ascites) or pericardial effusion.

12. The method of claim 10 or 11 , wherein the oncolytic herpes simplex virus is administered to a body cavity surrounding or contacting the cancer.

13. The method of any one of claims 10 to 12, wherein the oncolytic herpes simplex virus is administered after complete or partial drainage of effusion fluid.

14. The method of any one of claims 10 to 13, wherein the oncolytic herpes simplex virus is administered to effusion fluid associated with the cancer.

15. The method of any one of claims 10 to 14, wherein a fluid formulation of the oncolytic herpes simplex virus is administered to a body cavity surrounding or contacting the cancer and/or to said effusion fluid.

16. A method for treating a cancer with an oncolytic herpes simplex virus, the method comprising selecting a subject that has a cancer and has effusion fluid in which an oncolytic herpes simplex virus is stable, and administering to said subject a

therapeutically effective amount of the oncolytic herpes simplex virus, thereby treating the cancer.

17. An oncolytic herpes simplex virus for use in a method of treating a cancer, wherein the treatment involves selecting a subject that has a cancer and has effusion fluid in which an oncolytic herpes simplex virus is stable, and administering to said subject a therapeutically effective amount of the oncolytic herpes simplex virus.

18. A kit of parts comprising a container having an oncolytic herpes simplex virus therein, and instructions for determining the stability of the oncolytic herpes simplex virus in control media and in one or more effusion fluid samples.