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Updated: Jun 12, 2026
Microarray-based Identification of Individual HERV Loci Expression: Application to Biomarker Discovery in Prostate Cancer
Published on: November 2, 2013
PSMA+ Extracellular Vesicles Are a Biomarker for SABR in Oligorecurrent Prostate Cancer: Analysis from the STOMP-like
Jack R Andrews1, Yohan Kim2, Edlira Horjeti2
1Department of Urology, Mayo Clinic, Scottsdale, Arizona.
Purpose:
Two randomized clinical trials (STOMP and ORIOLE) demonstrated that stereotactic ablative radiotherapy (SABR) can prolong androgen-deprivation therapy-free survival or progression-free survival (PFS) in patients with metachronous oligometastatic castration-sensitive prostate cancer (omCSPC). Although most patients with omCSPC have a more modest delay in progression, a small subset achieves a durable response following SABR. We investigated the prognostic and predictive value of circulating prostate-specific membrane antigen-positive (PSMA+) extracellular vesicles (EV) and PSA in a biomarker correlative study using blood samples from three independent patient cohorts.
Experimental Design:
Plasma samples from 46 patients with omCSPC on the ORIOLE trial and 127 patients with omCSPC on the STOMP trial protocol treated with SABR were included in the study. Pre-SABR PSMA+EV levels (EV/mL) were measured by nanoscale flow cytometry. Kaplan-Meier curves and logistic regression models were used to determine the association of PSMA+EV and PSA levels with clinical outcomes.
Results:
In the pooled cohorts, the median biochemical PFS were 26.1 and 15.0 months (P = 0.005), and the median radiographic PFS were 36.0 and 25.0 months (P = 0.003) for PSMA+EV-low and -high groups, respectively. The combination of pre-SABR low levels of both PSMA+EV and PSA was associated with a lower risk of radiographic progression (HR, 0.34, 95% confidence interval, 0.18-0.58; P = 0.0002). In the ORIOLE cohort, which included both an SABR arm and an observation arm, low PSMA+EV was predictive of benefit from SABR (P = 0.012).
Conclusions:
PSMA+EV is a novel prognostic and predictive biomarker of radiographically occult tumor burden in omCSPC. PSMA+EV may inform clinical decisions about identifying patients who will achieve a durable benefit from consolidative SABR alone.
