Circulating Tumor Cells and Clinical Outcomes in Men with Metastatic Castration-sensitive Prostate Cancer Treated with Enzalutamide and Docetaxel: An Analysis of the ENZADA Trial.

We evaluated the prognostic value of circulating tumor cell (CTC) counts and androgen receptor splice variant 7 (AR-V7) status at baseline and after docetaxel in the previously published ENZADA trial. We analyzed data for 35 participants with both baseline and postdocetaxel CTC counts. CTC count status at two thresholds (≥2 vs <2 cells/μl; ≥3 vs <3 cells/μl) was not prognostic for a 26-wk or 52-wk prostate-specific antigen (PSA) complete response (CR), overall survival (OS), or time to castration resistance (TTCR). CTC count status (>0 vs 0 cells/μl) after docetaxel was not associated with 26-wk PSA CR, OS, or TTCR. However, there was a trend towards a higher 52-wk PSA CR rate among those with detectable CTCs after docetaxel (92% vs 52%; Patient summary: For men with metastatic prostate cancer treated with hormone therapies and chemotherapy, we looked at whether the level of tumor cells circulating in the blood (CTCs) was associated with the PSA (prostate-specific antigen) response and survival time. The CTC level was checked before treatment and after six doses of chemotherapy. We found no association with prostate cancer outcomes. However, in the group of patients whose PSA became undetectable after treatment, a CTC increase after chemotherapy identified men with a higher risk of cancer progression and death.