Development of a CTC Based Assay to Characterize MAOA Expression in Metastatic Prostate Cancer

MAOA over-expression is associated with resistance to androgen-targeting and cytotoxic agents in prostate cancer; this AACR 2025 poster from the Ellison Medical Institute and USC develops a CTC-based assay that measures MAOA on circulating tumor cells from whole blood, across 79 samples from 46 patients with metastatic disease.

Presented by USC.

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• MAOA-positive CTCs were far more common in castrate-resistant disease than in castrate-sensitive disease. Of 79 blood samples, 45% of the 40 castrate-resistant (CRPC) samples carried MAOA+ CTCs versus 10% of the 39 castrate-sensitive (CSPC) samples (18/40 vs 4/39; p<0.05, Fisher’s exact test) — a difference measured across samples drawn at various treatment timepoints, not across the 46 patients they came from.
• Dual CTC/MAOA positivity at baseline was associated with worse overall survival. In castrate-resistant patients, Cox univariate analysis returned a hazard ratio of 4.31 for CTC+/MAOA+ (95% CI 1.12–16.6; p=0.034), while in the same analysis CTC positivity alone returned a higher but far less precisely estimated hazard ratio that did not reach significance (HR 6.71, 95% CI 0.84–53.8; p=0.073).
• The assay pairs AccuCyte preparation and CyteFinder imaging with a custom MAOA RarePlex stain, and the authors frame it as a pilot. Nucleated cells from whole blood were stained on a Leica BOND RXm automated stainer, CTCs were identified as CK+/EpCAM+, CD45−, and single-cell MAOA was read as mean fluorescent intensity; across the 46-subject cohort (25 castrate-sensitive, 21 castrate-resistant) the conclusion claims only “potential clinical utility” for a CTC-based MAOA assay that “merits additional validation in expanded patient cohorts.”