The combination of microRNA-371a-3p and 375-5p can distinguish viable germ cell tumor and teratoma from necrosis in postchemotherapy retroperitoneal lymph node dissection specimens.

Background: To identify a combination of microRNAs (miRNA) to differentiate between viable tumor (V) or teratoma (T) and necrosis/fibrosis (N) in pcRPLND specimens of metastatic germ cell tumor (GCT) patients with residual masses ≥1 cm after chemotherapy. Biomarker guided therapy could reduce overtreatment with pcRPLND in patients with only N.

Methods: We selected 48 metastatic GCT patients who had undergone pcRPLND. V, pure T and N was shown in the resected tissue of 16 patients, respectively. Of these areas total RNA was isolated and miRNA expression was analyzed for miR-371a-3p, 375-3p, and 375-5p using qPCR. ROC analysis was performed for each miRNA and for all combinations in order to determine the discriminatory capacity of V and T . N.

Results: On comparing V . N miR-371a-3p achieved the highest fold change (FC) of 31.1 (P=0.023) while for T . N miR-375-5p performed best (FC 64.2; P<0.001). Likewise, the most accurate AUC for V was 0.75 using miR-371a-3p, for T 0.80 using miR-375-5p. Combining the best performing miRNAs for V and T resulted in an AUC of 0.94 with a sensitivity of 93.75, specificity of 93.75, PPV of 96.8 and NPV of 83.3.

Conclusions: By combining miR-371a-3p and miR-375-5p in pcRPLND tissue samples V and T could be distinguished from necrosis/fibrosis with great accuracy. This combination of miRNAs might serve as new biomarker in the future, in order to spare miRNA-negative patients from pcRPLND. However, further studies analyzing patient's serum are needed to confirm the clinical impact of these biomarkers.