Background: Olaparib is a PARP-inhibitor that has demonstrated efficacy in ovarian cancer in both platinum-sensitive and platinum-resistant relapse. BRCA mutations have been identified as an important predictive factor for response to olaparib, however in Study 19 progression free survival (PFS) was also improved in BRCA wildtype (BRCAwt) patients (1). A preclinical study showed synergism between doxorubicin and olaparib in 2D and 3D models of ovarian cancer (2). The combination of pegylated liposomal doxorubicin (PLD) 40 mg/m2 and olaparib 400 mg bid (capsule formulation) was considered tolerated and suitable in a phase I trial (3). Methods: This is a multicenter single arm phase II trial in women with platinum-resistant relapsed ovarian cancer. Patients receive Pegilated liposomal doxorubicin (PLD) 40 mg/m2 every 28 days and olaparib 300 mg bid tablets for 6 cycles followed by olaparib 300 mg bid maintenance until toxicity or disease progression. Primary endpoint is progression-free survival at 6 months (PFS6m). Secondary endpoints are PFS, overall-survival, response rate, quality of life, and growth modulation index. Key inclusion criteria are: 1) Serous or endometrioid ovarian cancer 2) Platinum-resistant relapse (between 28 days and 6 months after last platinum-containing chemotherapy (CT)) 3) Previous PLD is allowed if administered as part of a platinum-sensitive recurrence and > 6 months before inclusion 4) BRCA mutant patients are eligible after only 1 previous CT line, 5) BRCAwt or unknown are eligible after at least 2 previous platinum sensitive lines 6) no more than 3 CT lines are allowed, 7) Hemoglobin > 10 g/dl and 8) left ventricle ejection fraction > 50%. Sample size calculation assumed that PFS6m 40% or higher would be of interest for further investigation; with 90% power and a 2-sided alpha error 0.05 the number of patients needed will be 32 patients. Enrolment was initiated in December 2017 and the first patient has been enrolled. Clinical trial information: NCT03161132