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ESMO 2017: Biological assessment of viable germ cell tumor in patients with seminoma and non-seminoma using miR371

Madrid, Spain (UroToday.com) Dr. Nappi from British Columbia, Canada and colleagues presented results of their biological assessment of viable germ cell tumor (GCT) using miR371 at today’s poster session at ESMO 2017. The pathological constitution of residual nodes after chemotherapy or of the borderline enlarged retroperitoneal lymph nodes in clinical stage I (CSI) GCT patients on surveillance is challenging, especially in tumor markers negative patients. Currently, accurate assessment requires pathological confirmation with RPLND or clinical follow-up to establish a pattern of growth. A plasma-based biomarker approach to identify patients with viable tumor would be uniquely valuable.

Formalin-fixed paraffin embedded (FFPE) and plasma from GCT patients were used for miRNAs extraction. Non-cancer FFPE testicular tissue and plasma from healthy volunteers were used as negative controls. miR371 expression was detected by RT-PCR and relative expression calculated. miR-93-5p was used as positive internal control. Results were analyzed for associations with clinicopathologic features using Fisher’s exact test. miR371 was over-expressed in all the primary testicular (n = 4) and mediastinal (n = 3) samples while it was undetectable in the atrophic testis (n = 1) and mediastinal or gonadal teratoma (n = 2), confirming the applicability of the technique to the FFPE samples. There were 21 metastatic samples analyzed: two lung, one brain, 17 lymph nodes and one IVC tumor thrombus. The samples were collected prior to (n = 2) or after (n = 12) chemotherapy, while 7 pts were treated only with surgery. miR371 was undetectable in any samples (0/9) with no viable tumor on pathological examination and over-expressed in 11/12 (91.6%) of those with viable GCT (OR 145.7; p < 0.0001). 90% of patients with positive miR-371 had negative tumor markers (100% of seminoma and 75% of nonseminoma), while no patients with negative miR-371 had positive tumor markers. Plasma miR-371 also showed high correlation with viable tumor.

In conclusion, this study showed that elevated plasma levels of miR-371 correlated with the presence of active germ cell malignancy. These encouraging findings suggest that plasma miR371 levels may lead to biological rather than radiographic assessment of the presence of active GCT in patients with seminoma and nonseminoma, helping to further delineate appropriate individualized treatment.

Speaker: Lucia Nappi, British Columbia Cancer Agency, Vancouver, Canada

Co-Authors: M. Thi (Vancouver, Canada) L. Fazli (Vancouver, Canada) K. Chi (Vancouver, Canada) B. Eigl (Vancouver, Canada) C. Nichols (Murray, United States of America) M. Gleave (Vancouver, Canada) C. K. Kollmannsberger (Vancouver, Canada)

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, Twitter: @zklaassen_md at the European Society for Medical Oncology Annual Congress - September 8 - 12, 2017 - Madrid, Spain