Prognostic implication of blood immune cell composition in Metastatic Castration-Resistant Prostate Cancer (mCRPC)

The prognosis of patients with metastatic castration-resistant prostate cancer (mCRPC) is variable. Several blood-related prognostic factors have been reported, including transcriptional profiling of whole blood and neutrophil to lymphocyte ratio. We aimed to address the contribution of distinct whole blood immune cell components to the prognosis of these patients. Subjects/Patients and Methods: Pre-treatment whole blood samples from chemotherapy-naïve mCRPC patients were prospectively collected before treatment with enzalutamide. The study consisted of a training cohort including 98 patients treated with enzalutamide in a phase 2 biomarker clinical trial (NCT02288936) The study involved serial whole-blood sample collection from participants using PAX-Gene RNA, with samples stored at -80ºC. Collection times included before treatment, at 12 weeks during treatment, and at tumor progression or end of treatment. The focus here is on samples taken prior to treatment. For RNA extraction and microarray analysis, blood samples in PAXgene RNA tubes underwent isolation and purification as per the manufacturer's protocol. RNA quality was assessed using NanoDrop 2000 and Bioanalyzer 2100, with only RNA samples having an RNA integration number (RIN) of seven or above being used. Complementary DNA (cDNA) was synthesized from these RNA samples and prepared for hybridization. Hybridization used the GeneChip Human Transcriptome Array HTA 2.0, incubating with single-strand DNA (ssDNA) for 16 hours. Post-hybridization, non-specific probes were washed away, and the array was scanned with the GeneChip Scanner 3000.