This is a randomized phase II study, aimed at evaluating the efficacy (through progression free survival at 6 months) and safety of 5 different treatments involving atezolizumab, bevacizumab and/or acetylsalicylic acid in advanced recurrent platinum-resistant ovarian cancer patients in order to select the optimal treatments for further development in Phase III.

Inclusion Criteria:

Recurrent, histologically proven, platinum-resistant, epithelial ovarian, fallopian tube and primary peritoneal cancer in advanced or metastatic stage. Histological diagnosis by image guided biopsy, laparoscopy or laparotomy. Tumors diagnosed on cytology only and borderline tumors are excluded.

At least one lesion accessible to biopsy without putting patient at risk

WHO PS: 0-2 for patients having received no more than two previous lines of therapy. WHO PS: 0-1 for patients having received >2 previous lines of therapy

Prior chemotherapy or bevacizumab:

Any number of platinum-based chemotherapy lines are allowed but a maximum of 2 previous non-platinum containing lines

Prior treatment with bevacizumab or other targeted agents against Vascular Endothelial Growth Factor (VEGF) or VEGF receptor is allowed, but at least 18 weeks must have elapsed since their last administration

Eligible patients with ≤ 2 previous treatment lines must have been previously exposed to bevacizumab or other targeted agents against VEGF or VEGF receptor

Patients may have had prior therapy providing the following conditions are met:

Radiation therapy: wash-out period of 14 days prior to the first study treatment; exception: single fraction radiotherapy with the indication of pain control

Systemic anti-tumor therapy: wash-out period of 21 days prior to the first study treatment

Recovery from any toxic effects of prior therapy to ≤ Grade 1 per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE v4.03) except fatigue or alopecia.

Exclusion criteria:

Age <18 years

Life expectancy of < 12 weeks

No adequate hematologic and end organ function

Use of acetylsalicylic acid, NSAIDs or other COX-2 inhibitors that cannot be stopped at baseline and for the whole duration of the study.