65 Background: Androgen deprivation therapy (ADT) combined with an androgen receptor pathway inhibitor (ARPI) represents the standard of care for metastatic hormone-sensitive prostate cancer (mHSPC). However, no consensus exists regarding which patients benefit from treatment intensification with docetaxel (triplet therapy). Circulating erythroblasts, a marker of bone marrow infiltration, represent a widely available yet unvalidated biomarker for treatment guidance. We investigated the predictive value of baseline erythroblasts in selecting mHSPC patients for triplet therapy. Methods: This multicenter retrospective study included patients treated between 2022 and 2024 for high-volume mHSPC according to CHAARTED criteria who received either doublet (ADT+ARPI) or triplet (docetaxel+ADT+ARPI) therapy. The primary endpoint was 2-year progression-free survival (PFS), defined as time from treatment initiation to clinical or radiological progression, initiation of new systemic therapy, or death from any cause. Cardinality matching at a 2:1 ratio was performed to balance potential confounding variables. Results: A total of 234 patients were included (141 triplet, 93 doublet). After matching, 122 patients remained in the triplet group and 61 in the doublet group. With median follow-up of 23.5 months for the triplet group and 33.9 months for the doublet group, 2-year PFS rates were 71.9% and 57.8%, respectively (HR 0.62, 95% CI 0.40-0.95, p=0.027). Subgroup analysis demonstrated significantly greater survival benefit from triplet therapy in patients with detectable baseline erythroblasts (PFS: HR 0.29, 95% CI 0.11-0.76; OS: HR 0.24, 95% CI 0.07-0.77) compared to those without erythroblasts (PFS: HR 0.66, 95% CI 0.37-1.19; OS: HR 0.52, 95% CI 0.26-1.06). Conclusions: The baseline presence of circulating erythroblasts serves as a strong predictive marker for benefit from docetaxel intensification in patients with high-volume mHSPC. This readily available biomarker may guide patient selection for triplet therapy, pending prospective validation.
Stativko et al. (Sun,) studied this question.