Impact of adding carboplatin to docetaxel chemotherapy on testosterone levels and treatment outcomes in metastatic docetaxel-resistant prostate cancer

Docetaxel resistance, particularly post-androgen-receptor targeted therapy (ART), undermines its clinical utility in metastatic castration-resistant prostate cancer (mCRPC). This study explores the impact of docetaxel plus carboplatin (DC) chemotherapy on serum testosterone levels in metastatic docetaxel-resistant prostate cancer (mDRPC) patients. 123 mDRPC patients were categorized into three groups: (1) no previous ART (n = 65), (2) previous ART with serum free testosterone (FT) > detection limit (DL) at baseline (n = 31), and (3) previous ART with FT < DL at baseline (n = 27). Salvage DC chemotherapy led to significant reductions in FT and total testosterone (TT) levels in groups 1 and 2 (p < 0.05). Group 1 saw FT decrease from 0.85 pg/mL to below the DL (< 0.18 pg/mL) with 54.3% achieving complete reduction (CR); group 2 showed FT decrease from 0.28 pg/mL to below the DL with 67.7% achieving CR; group 3 had baseline FT values already below the DL with 96.3% maintaining this level. TT reductions to below the DL occurred in all groups. Low FT was an independent predictor for better PFS and for improved OS in groups 1 and 2. Our data indicate that adding carboplatin may improve the therapeutic effects of docetaxel in a castration-dependent setting.