Use of concomitant G-CSF in maintaining efficacious dose and safe delivery of docetaxel in combination with darolutamide in ARASENS: A phase III study

BACKGROUND: We assessed the impact of granulocyte colony-stimulating factor (G-CSF) use and docetaxel relative dose intensity (RDI) on the safety profile of the ARASENS (NCT02799602) triplet regimen with darolutamide in patients with metastatic hormone-sensitive prostate cancer. METHODS: Patients were randomized to darolutamide 600 mg orally twice daily or placebo, with androgen deprivation therapy (ADT) and docetaxel. Baseline characteristics, G-CSF use, and safety were analyzed according to docetaxel RDI (≤85 % vs >85 %). RESULTS: Of 1273 patients with docetaxel RDI data (darolutamide n = 637; placebo n = 636), > 97 % received an efficacious dose of docetaxel (RDI >80 %). Patient demographics and baseline disease characteristics were generally similar between RDI subgroups; > 60 % of patients with RDI ≤ 85 % were from the Asia-Pacific region. Concomitant G-CSF, with/without docetaxel dose modification, was used in 42.4 % (darolutamide) and 44.6 % (placebo) of patients, mainly as secondary prophylaxis; 61.3 % (darolutamide) and 64.4 % (placebo) received both docetaxel dose modifications and G-CSF. Grade ≥ 3 treatment-emergent adverse events (TEAEs), grade ≥ 3 neutropenia, and grade ≥ 3 febrile neutropenia were higher with docetaxel RDI ≤ 85 %, but docetaxel discontinuation rates were similar between subgroups (RDI ≤85 %: darolutamide 7.2 %, placebo 10.8 %; RDI >85 %: darolutamide 8.1 %, placebo 10.5 %). TEAEs leading to docetaxel dose modification were more frequent with docetaxel RDI ≤ 85 % (darolutamide 92.8 %; placebo 97.3 %) versus RDI > 85 % (darolutamide 26.0 %; placebo 25.3 %). CONCLUSION: Appropriate docetaxel dose modifications and early G-CSF use allowed almost all patients to receive an efficacious dose of docetaxel in combination with darolutamide and ADT and may prevent neutropenic complications in patients receiving docetaxel. PRIOR PRESENTATION: Previously presented at the 2025 American Society of Clinical Oncology Genitourinary Cancers Symposium, San Francisco, CA.