Circulating Tumor Cell Count and Overall Survival in Patients With Metastatic Hormone-Sensitive Prostate Cancer.

Area of Science:

• Oncology
• Biomarker Discovery
• Prognostic Studies

Background:

• Metastatic hormone-sensitive prostate cancer (mHSPC) outcomes vary, necessitating better prognostic tools.
• Peripheral blood circulating tumor cell (CTC) count shows promise as a liquid biomarker in mHSPC, similar to its established role in mCRPC.

Purpose of the Study:

• To evaluate the prognostic significance of CTC count in men with mHSPC.
• To determine if CTC count can improve existing prognostic models for mHSPC patients.

Main Methods:

• A prospective analysis of CTC counts from the phase 3 S1216 clinical trial in mHSPC patients.
• Peripheral blood samples were collected at baseline and progression, with CTCs enumerated using an FDA-cleared platform.
• CTC counts were categorized (0, 1-4, ≥5 CTCs/7.5 mL) and analyzed for association with overall survival (OS), progression-free survival, and PSA response.

Main Results:

• Of 503 evaluable baseline samples, 66.8% had 0 CTCs, 21.3% had 1-4 CTCs, and 11.9% had ≥5 CTCs.
• Median OS was 27.9 months for ≥5 CTCs/7.5 mL vs. 56.2 months for 1-4 CTCs/7.5 mL vs. not reached for 0 CTCs.
• Elevated baseline CTC counts (≥5 CTCs/7.5 mL) significantly increased the hazard of death (HR 3.22) and progression (HR 2.46) compared to 0 CTCs.
• Adding CTC count to existing models improved 3-year survival prediction (AUC increased from 0.73 to 0.79).

Conclusions:

• Baseline CTC count is a validated, non-invasive prognostic biomarker in mHSPC.
• CTC count significantly refines prognostic assessment, identifying patients with divergent survival outcomes.
• This biomarker can guide treatment decisions and identify candidates for intensified or novel therapeutic clinical trials.