engleski

TERT gene fusions characterize a subset of metastatic leydig cell tumors

Objective: Metastatic Leydig cell tumors (LCT) are rare, difficult-to-treat malignancies without known underlying molecular-genetic events. An index case of metastatic LCT showed an LDLR-TERT gene fusion upon routine genetic profiling for detection of therapeutic targets, which was then followed by an investigation into a cohort of additional LCTs. Patients and methods: Twenty-nine LCT (27 male and 2 female patients) were profiled using next- generation sequencing and immunohistochemistry. Results: TERT gene fusions were detected only in testicular metastatic LCTs, in 3 of 7 successfully analyzed cases (RMST:TERT, LDLR:TERT, and B4GALT5:TERT). TOP1 and CCND3 amplifications were identified in the case with a B4GALT5:TERT fusion. A TP53 mutation was detected in 1 metastatic tumor without a TERT fusion. Five primary (4 testicular and 1 ovarian) LCTs showed multiple gene amplifications, without a consistent pattern. A single metastatic ovarian LCT showed BAP1 mutation and copy number amplifications affecting the NPM1, PCM1, and SS18 genes. At the protein level, 4 of 7 metastatic and 6 of 10 primary testicular LCTs overexpressed Topo1. Androgen receptor was overexpressed in 10 of 13 primary testicular tumors and 2 of 5 metastatic testicular LCTs (without detectable ARv7 messenger RNA or ARv7 protein). Only 1 metastatic testicular LCT exhibited a high tumor mutational burden ; all tested cases were microsatellite instability stable and did not express programmed cell death ligand 1. Conclusions: Our study for the first time identified TERT gene fusions as a main genetic alteration and a potential therapeutic target in metastatic LCTs. Topo1 and androgen receptor may guide decisions on chemotherapy and/or hormone therapy for selected individual patients.

leydig cell tumors ; molecular profiling ; sequencing ; sex cord–stromal tumors ; targeted therapy

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