This study tests a new treatment for women with platinum-resistant/refractory ovarian cancer, which means their cancer does not respond well to traditional platinum-based chemotherapy. The study compares two groups: one gets an experimental treatment called Olvi-Vec (a virus-based therapy that helps the immune system fight cancer), followed by standard chemotherapy and a drug called bevacizumab, which helps prevent the growth of new blood vessels in tumors. The other group receives the doctor's choice of chemotherapy and bevacizumab.

• Participants will need at least 3 prior treatments and must not have certain types of infections or other health issues.
• The study involves a single cycle of Olvi-Vec administered over two consecutive days, followed by chemotherapy.
• Participants may need to provide biological samples for testing, and regular monitoring is required.

This study aims to find out if the new treatment can make tumors more sensitive to chemotherapy and improve survival outcomes. Participants should discuss potential risks and benefits with their doctor before joining.