Phase II Trial Evaluating Olaparib Maintenance in Patients with Metastatic Castration-Resistant Prostate Cancer Responsive or Stabilized on Docetaxel Treatment: SOGUG-IMANOL Study

The SOGUG-IMANOL trial was a phase 2, uncontrolled, Spanish multicenter study to assess the effect of maintenance treatment with olaparib on radiographic progression-free survival (PFS) in patients with metastatic castration-resistant prostate cancer (mCRPC) who achieved partial or complete response or disease stabilization on docetaxel treatment and had a documented germline/somatic mutation in any of the homologous recombination repair (HRR) genes. Patients received olaparib 300 mg orally twice daily. From the screened population (n = 134), 26 (19.4%) somatic mutations were found, and 14 patients were included in the study. The median radiographic PFS was 11.1 (95%CI, 5.7 to 16.5) months. The median PSA-PFS was 3.5 (95%CI, 1.0 to 6.0) months, and the median clinical PFS was 14.7 (95%CI, 1.8 to 27.5 months). Clinical benefit was observed in 12 patients (85.7%, 95%CI 67.4% to 100%), including two patients with partial response and 10 with stable disease. Six patients reported grade 3–5 adverse events: asthenia (n = 3), anemia (n = 2) and neutropenia (n = 1). In this setting, olaparib has been shown to be an efficacious maintenance treatment in terms of radiographic PFS and clinical benefit, becoming a therapeutic option for some patients harboring an HRR gene mutation and in scenarios where further investigation is needed.