Long-term safety of darolutamide in patients with metastatic castration-resistant prostate cancer

90 Background: Darolutamide, a structurally distinct and highly potent androgen receptor inhibitor, had a consistently favorable safety and tolerability profile in patients with nonmetastatic castration-resistant prostate cancer in ARAMIS, and discontinuation rates due to adverse events (AEs) remained consistently low after longer follow-up. In previously reported phase 1/2 studies in patients with metastatic castration-resistant prostate cancer (mCRPC), darolutamide was well tolerated for up to 25 months. We report the safety and tolerability of extended treatment with darolutamide in these mCRPC studies. Methods: Data from three phase 1/2 studies (NCT02363855, NCT01317641/NCT01429064, and NCT01784757) in patients with mCRPC were pooled for analysis of long-term safety. Results are summarized descriptively. Results: Of 173 patients with mCRPC evaluable for safety in the 3 studies, 13 patients received > 2 years of darolutamide treatment; median duration of treatment was 38 months (range 24–90). Six patients received > 4 years of darolutamide treatment. Nine of 13 patients with > 2 years of darolutamide therapy initially received 600 mg BID; others received 200 mg (n = 1), 300 mg (n = 1), or 700 mg (n = 2) BID. Median age was 68 years in the > 2-years group, and most patients were white. Patients were enrolled from France (n = 4), Latvia (n = 3), United Kingdom (n = 3), Finland (n = 2), and Japan (n = 1). Most patients had normal renal function (n = 10) and hepatic function (n = 10), 12 patients had Eastern Cooperative Oncology Group performance status of 0, and 9 patients had a Gleason score ≥7. Prior systemic anticancer treatments taken by more than 1 patient were bicalutamide (n = 10); cyproterone (n = 3); and triptorelin and leuprorelin (n = 2 each). No patient received prior chemotherapy. All 13 patients reported AEs, most grade 1 or 2; 6 reported grade 3 AEs. Treatment-related AEs were reported in 5 patients, and all were grade 1 in severity. Serious AEs were reported in 6 patients, and all were judged not related to darolutamide. One patient treated with darolutamide for > 2 years had an AE (new neoplasm; not related to darolutamide) that led to treatment discontinuation. Conclusions: Extended darolutamide treatment > 2 years in this small group of patients with mCRPC was generally well tolerated, with safety and tolerability consistent with that previously reported. Clinical trial information: NCT02363855, NCT01317641/NCT01429064, and NCT01784757.