Additional cycles of docetaxel in combination with androgen deprivation therapy (D-ADT) in metastatic hormone-sensitive prostate cancer (mHSPC): Efficacy and feasibility analysis.

e17074 Background: Several phase III trials have assessed efficacy and safety of 6 cycles of docetaxel combined to androgen deprivation therapy (D-ADT) in metastatic hormone-sensitive prostate cancer (mHSPC). This is the current standard of care for a subgroup of patients. We aimed to assess whether treatment beyond 6 cycles of docetaxel prove to be more effective than the standard of care. Methods: We retrospectively collected data from patients with histologically confirmed adenocarcinoma of the prostate and radiologically proven metastatic disease treated at a large tertiary care center. All patients with mHSPC were treated in first-line with D-ADT (75 mg/m 2 ) intravenously on the first day of each 21-day cycle. A subset of patients was treated beyond the standard of 6 cycles. Clinical and pathological variables were examined, as were treatment-related toxicities; progression free survival on D-ADT (PFS1), progression free survival on subsequent therapy (PFS2) and overall survival (OS) were calculated from start of treatment to progression or death by log-rank test. Results: Between 2015-2023 a total of 108 mHSPC patients were treated and observed for a median time of 13.8 months. Mean age was 66.2 years (range 46.9-82.7), and 75.0% had GS≥8, 65.7% a CHAARTED high-volume and 69.4% LATITUDE high risk disease. 72 pts. were treated with ≤ 6 cycles (D-ADTstand) (4.2% 1-2 cycles; 95.8 % ≥3 cycles; mean 5.2 cycles) and 36 were treated with > 6 cycles docetaxel (D-ADTadd) (27.8% 7-8 cycles; 72.2% ≥9-10 cycles, mean 9.2 cycles). Frequency of toxicities did not differ in the groups. No significant differences were observed in median PFS1 (10.3 vs. 13.4 mos.) and PFS2 (6.3 vs. 6.6 mos.). Median OS in the D-ADTstand group was 39.8 mos., median OS in the D-ADTadd group was not yet reached. Conclusions: While more than 6 cycles of D-ADT in mHSPC proved to be feasible without significant additional toxicity, efficacy is not superior compared to the standard of 6 cycles. Overall survival data is not mature yet, but the benefit of more chemotherapy upfront is debatable and leverages further studies in light of the upcoming triplet combinations in mHSPC, that presumably will render doublet D-ADT obsolete in future. [Table: see text]