Measuring microRNA-371a-3p in testicular germ cell tumors-making the test ready for clinical routine practice.

The M371-Test enables standardized measurement of miR-371a-3p in serum, which represents a highly sensitive and specific biomarker for testicular germ cell tumors (GCTs). The current protocol requires immediate centrifugation, freezing, and cold-chain shipping to the laboratory, which poses significant barriers to practical use of the test. Previous studies suggested that plasma from the S-Monovette cfDNA Exact may offer a simplified preanalytical pathway with extended sample stability at ambient temperature, potentially improving test accessibility. To evaluate this approach, we are conducting a prospective multicenter study with a target enrollment of ≥ 250 patients comparing M371-Test performance in paired plasma and serum samples; this report presents an interim analysis of 109 eligible patients (67 GCT cases, 42 controls). M371-Test performance in plasma was very similar to serum, with sensitivities of 92.5% and 94.0%, respectively, while specificity was 100% in plasma versus 92.9% in serum. Subgroup analysis showed that the difference in specificity was concentrated in the post-treatment remission subgroup (84.6% serum vs. 100% plasma). These findings indicate that plasma and serum yield comparable diagnostic performance with the M371-Test. The simplified preanalytical workflow associated with the S-Monovette cfDNA Exact warrants formal stability and robustness evaluation in the completed study. If confirmed in the full cohort, this approach may offer a more practical pathway for miR-371a-3p-based GCT diagnostics in routine practice.