A research study evaluating a new oncolytic virus, THEO-260, in patients with advanced ovarian cancer. The trial will investigate different doses of THEO-260 administered by the intraperitoneal route to identify a dose that is safe, well tolerated, and exhibits preliminary evidence of anti tumour activity.

• Inclusion Criteria:
• Confirmed histological diagnosis of advanced high grade serous or endometrioid cancer of the fallopian tube, primary peritoneum or ovary either on archival biopsy or fresh tumour biopsy.
• Platinum-resistant or refractory disease: platinum-resistance is defined as radiological progression within 6 months of last cycle of platinum treatment; platinum refractory disease is defined as radiological progression during the 3 months following the first dose with platinum treatment.
• Life expectancy of > 6 months.
• ECOG performance status of 0 or 1.
• Measurable disease as per RECIST V1.1.
• No clinical history of bowel obstruction in past 3 months or no clinical signs or symptoms of bowel obstruction.

Exclusion Criteria:

• Prior anti-cancer treatment or Investigational Product within 28 days or 5 half-lives, prior to first dose of THEO-260.
• Prior treatment with a group B adenovirus.
• Radiation therapy within 4 weeks of first dose of THEO-260
• Clinical evidence of cerebral metastases or Central Nervous System (CNS) involvement including leptomeningeal disease. Patients with previous cerebral metastases must have no evidence of progression or haemorrhage after treatment.
• Uncontrolled pleural effusion or pericardial effusion requiring recurrent drainage procedures (as defined as once monthly or more frequently).
• Prior pneumonitis or history of interstitial lung disease.
• Confirmed QTcF ≥470 ms on screening 12-lead ECG or history of Torsades de Pointes or history of congenital long QT syndrome.
• Concomitant medications that prolong the QTc interval and/or increase the risk for Torsades de Pointes.
• Patients with active hepatitis infection or hepatitis C. Patients with past hepatitis B virus (HBV) infection or resolved HBV infection are eligible.
• Active infection with tuberculosis.
• Active infection with severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2).
• Patients with active human immunodeficiency virus (HIV) infection or known history of HIV infection.
• Active infection requiring IV antibiotics within 2 weeks prior to first dose of THEO-260, or long-term oral therapy for systemic infection.
• Known contra-indications or hypersensitivity to the excipients of THEO-260.
• Active autoimmune disease that has required systemic treatment in the past 2 years.
• Known heart failure New York Heart Association (NYHA) Class 2-4.
• Known contra-indications or hypersensitivity to acetominophen.
• Known alcohol consumption in excess of 2 units per day.
• Left ventricular ejection fraction (LVEF) <45%, unstable angina, serious uncontrolled cardiac arrhythmia, a myocardial infarction within 6 months prior to trial enrolment or a history of myocarditis.
• Arterial oxygen saturation <92% on room air prior to first dose of THEO-260.
• Received any licensed or investigational vaccines within 30 days prior to Day 1