Clinical Validation of Circulating Tumor Cell Synaptophysin and Androgen Receptor Expression in Metastatic Prostate Cancer Phenotypes

Tissue biopsy can miss the neuroendocrine shift that chronic androgen receptor pathway inhibitor exposure can drive; this ASCO 2026 poster reports how synaptophysin and androgen receptor staining on circulating tumor cells compared with the tissue-defined phenotype in 52 patients with metastatic castration-resistant prostate cancer.

Presented by UW Medicine / Fred Hutch Cancer Center.

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• CTC synaptophysin and androgen receptor staining tracked the tissue-defined phenotype. Within the 14 AR-positive adenocarcinoma cases, AR-positive CTCs dominated over SYP-positive CTCs (p<0.0001); between cohorts, SYP-positive CTC burden was higher in the 13 neuroendocrine cases (p=0.0084) and AR-positive burden was higher in the adenocarcinoma cases (p=0.0004).
• CTC synaptophysin and androgen receptor expression showed strong concordance with the tissue-defined neuroendocrine phenotype, supporting liquid biopsy–based prostate cancer phenotyping. Read directly from circulating tumor cells in a routine blood draw, without a tissue biopsy.