• Signed and dated informed consent(s) by the participant or legal representative before any trial-related activities.

• Female over 18 years of age on day of signing informed consent(s).

• Diagnosis:

‣ Phase I part: Histologically confirmed ovarian cancer (including fallopian tube and primary peritoneal cancer) resistant to platinum (defined as progression of cancer within 183 days of the most recent dose of cisplatin or carboplatin) or refractory to platinum (defined as progression of cancer within 30 days of the most recent dose of cisplatin or carboplatin) ovarian cancer, which cannot be treated with curative intent with available therapies.

⁃ Phase Ib part: Platinum refractory/resistant ovarian cancer treated with up to one line of prior chemotherapy in refractory/resistant setting. Note: A regimen that contains only one or more biological agents and/or targeted therapies but no cytotoxic drug does not count as a line of chemotherapy Note: For both phase I and phase Ib, PARP inhibitors should be considered as indicated in clinical practice, prior to trial enrollment. Patients who have platinum-sensitive disease (no recurrence or progression within 183 days of the last dose of platinum-containing chemotherapy) but who have an allergy or severe intolerance to carboplatin and/or cisplatin may be included.

• At least one tumor (\>14 mm in diameter) or carcinomatosis must be available for local virus injection (intratumoral and/or intraperitoneal).

• The disease burden must be evaluable, but does not need to fulfil RECIST 1.1.

• Have adequate organ function as defined in the following values below. Specimens must be collected within 10 days prior to the start of study treatment.

• a. Hematological laboratory values i. Absolute neutrophil count (ANC): ≥1500/µL ii. Platelets: ≥ 100 000/µL iii. Hemoglobin: ≥9.0 g/dL or ≥5.6 mmol/L. Criteria must be met without packed red blood cell (pRBC) transfusion within the prior 2 weeks. Participants can be on stable dose of erythropoietin (≥ approximately 3 months. iv. Leukocytes (WBC) \> 3.0x10\^9/L b. Renal laboratory values i. Glomerular Filtration Rate (GFR): \>45 ml/min (CKD-EPI formula). c. Hepatic laboratory values i. Total bilirubin: ≤1.5 × Upper Limit of Normal (ULN) OR direct bilirubin ≤ULN for participants with total bilirubin levels \>1.5 × ULN (excluding patients with Gilber's Disease) ii. Aspartate Aminotransferase (AST) (SGOT) and Alanine Aminotransferase (ALT) (SGPT): ≤2.5 × ULN (≤5 × ULN for participants with liver metastases)

• Patients must be willing to use adequate forms of contraception from screening, during the trial, and for a minimum of 120 days after end of treatment, in accordance with the following:

• i. Women of childbearing potential: Barrier contraceptive method (i.e. condom) must be used in addition to one of the following methods: Intrauterine devices or hormonal contraception (oral contraceptive pills, implants, transdermal patches, vaginal rings or long-acting injections). ii. Women not of childbearing potential: Barrier contraceptive method (i.e. condom) must be used.

• Eastern Cooperative Oncology Group (ECOG)/World Health Organization (WHO) performance score of 0-1 at screening.

• Life expectancy longer than 3 months.

• Capable of understanding and complying with parameters as outlined in the protocol.