...CTC response defined as a decrease from ≥5 CTCs per 7.5 mL blood at baseline to <5 CTCs per 7.5 mL blood`PSA change from baseline at 12 weeks defined as the percent change in PSA from baseline at 12 weeks, according to PCWG2 criteria`Maximum PSA decrease defined according to PCWG2 criteria`Progression-free survival (PFS) defined as time from prescreening to the date of the first documentation of disease progression (PCWG2)`Overall survival (OS) calculated from the date of prescreening to death due to any cause`Grade 3-4 adverse events (AEs) and serious adverse events (SAEs) during cabazitaxel according to CTCAE v4.03 in second and third-line treatment`Cumulative administered dose of cabazitaxel in second and third-line treatment`AR-V7 mRNA expression as well as mRNA expression of other splice variants in CTCs indicated as absent (-) or present (+)`Cabazitaxel concentration in the blood and total systemic exposure to cabazitaxel, measured by the calculated area under the curve (AUC)`To explore the value of ctDNA quantification during cabazitaxel treatment to predict tumor progression...

...Circulating tumor cell (CTC) response rate`Prostate specific antigen (PSA) change from baseline`Maximum Prostate specific antigen (PSA) decrease`Progression-free survival`Overall survival`grade 3-4 adverse events and serious adverse events (SAEs)`Cabazitaxel concentration in the blood (measured in ng/mL)`Total systemic exposure to cabazitaxel (measured in mg/m2)`AR-V7 mRNA expression as well as mRNA expression of other splice variants in CTCs indicated as absent (-) or present (+) on a per-patient basis...

Baseline CTC biomarkers may be prognosticators for cabazitaxel-treated mCRPC patients. Cabazitaxel at lower (20 mg/sqm) dose was associated with poorer outcomes in AR-V7 positive patients compared to AR-V7 negative patients in a post hoc subgroup analysis....Among these patients, 8 (18%) had AR-V7 CTC expression....In patients treated with cabazitaxel 20 mg/sqm, median OS was shorter in AR-V7 positive than negative patients (6.6 versus 14 months, HR=3.46, 1.47–8.17], p=0.004)...the correlation between AR-V7 expressions and worse outcome was significantly associated with the initial reduced dose of cabazitaxel for OS (p = 0.056).