A randomized phase II study of secondary cytoreductive surgery in patients with relapsed ovarian cancer who have progressed on a PARP inhibitor as first-line maintenance therapy: the SOCCER-P study (KGOG 3067/JGOG 3036/APGOT-OV11).

Background: Although two recent phase III randomized controlled trials showed survival benefits of undergoing secondary cytoreductive surgery for an initial relapse of ovarian cancer, patients who received a poly-ADP ribose polymerase inhibitor (PARPi) as the first-line maintenance treatment, which is currently the standard treatment for advanced ovarian cancer, were not included in those trials. Therefore, determining an optimal treatment strategy, including secondary cytoreductive surgery, in patients whose cancer progresses even with PARPi treatment, is needed.

Primary objective: To determine whether secondary cytoreductive surgery is beneficial in patients who have progressed on PARPi maintenance treatment.

Study hypothesis: Secondary cytoreductive surgery followed by chemotherapy is superior to chemotherapy alone for patients who have progressed on PARPi maintenance treatment.

Trial design: The SOCCER-P study is a multicenter randomized phase II clinical trial. Patients who meet the eligibility criteria will be randomized to either undergo secondary cytoreductive surgery and subsequent platinum-based chemotherapy plus or minus bevacizumab, or to receive platinum-based chemotherapy plus or minus bevacizumab alone. Patients randomly allocated to the surgery group will undergo secondary cytoreductive surgery followed by six cycles of a physician's choice of platinum-based chemotherapy once they have recovered from surgery.

Major inclusion/exclusion criteria: The major inclusion criteria are as follows: first recurrence of disease with treatment-free interval from last platinum dose (TFIp) ≥6 months and progression during PARPi maintenance or treatment-free interval from last PARPi therapy (TFI_PARPi) <3 months. The major exclusion criteria are as follows: >1 line of prior chemotherapy, TFIp <6 months, and radiological signs suggesting metastases not accessible to surgical removal (complete resection is deemed not possible).

Primary endpoint: Progression-free survival.

Sample size: 124 patients.

Estimated dates for completing accrual and presenting results: Accrual completion approximately the end of 2026 and the results are expected after 2 years of follow-up in 2029.

Trial registration: NCT05704621.