Potential next generation markers of testicular germ cell tumors: miRNA-371a-3p

BACKGROUND

Testicular germ cell tumors (TGCTs) account for approximately 98% of all testicular cancers, predominantly affecting young to middle-aged men. Early diagnosis and treatment result in a cure rate of over 95%. However, conventional serum tumor markers (STMs) such as alpha-fetoprotein (AFP), β-human chorionic gonadotropin (β-hCG), and lactate dehydrogenase (LDH), which are recommended by NCCN and EAU guidelines, have limited sensitivity, often below 60%, which diminishes their clinical utility. Recently, miRNA-371a-3p, an embryonic stem cell-associated microRNA, has been identified as being specifically expressed in TGCTs. This microRNA can be reliably detected in peripheral blood and fulfills all seven Lange-Winfield criterias for tumor markers. Notably, miRNA-371a-3p has demonstrated superior diagnostic, therapeutic, and follow-up capabilities compared to conventional STMs in TGCTs. Its potential to replace conventional STMs in clinical practice is already recognized in several clinical guidelines.

METHODS

A PubMed search using subject headings and free-text terms related to MicroRNA-371a-3p in TGCT management was conducted. Relevant references were also tracked, and key studies were reviewed based on predefined exclusion criteria.

RESULTS

Out of 368 identified studies, 67 met inclusion criteria. These studies focused on MicroRNA-371a-3p's discovery, detection methods, diagnostic utility in TGCTs, and cost-effectiveness. First identified over a decade ago, microRNA-371a-3p is now established as a highly specific blood-based marker for TGCTs, valuable for diagnosis, monitoring, and follow-up, and more cost-effective than conventional STMs.

CONCLUSIONS

MicroRNA-371a-3p is a promising, highly sensitive marker for TGCTs, offering better performance and cost efficiency than conventional STMs, likely to become the next-generation diagnostic tool for TGCTs.

MicroRNAs in disease States

This review highlights the role of miRNAs in various diseases affecting major organ systems. miRNAs are small, non-coding RNA molecules that regulate numerous genes. Dysregulation of miRNAs is linked to many pathological conditions due to their involvement in gene silencing and cellular pathways. We discuss miRNA expression patterns, their physiological and pathological roles, and how changes in miRNA levels contribute to disease. Notably, miRNAs like miR-499 and miR-21 are implicated in heart failure and atherosclerosis. miRNA dysregulation is also associated with colorectal and gastric cancers, influencing tumorigenesis and chemoresistance. In neurological diseases, miRNAs exhibit diverse profiles that affect neurodevelopment and degeneration. Additionally, miRNAs modulate cell function in reproductive organs, impacting fertility and cancer progression. miRNAs such as miR-192 and miR-204 serve as biomarkers for nephropathy and acute kidney injury. These miRNAs are involved in skeletal muscle diseases, contributing to conditions like osteoporosis and sarcopenia. miRNAs function as oncogenes or tumor suppressors in cancer, highlighting their potential in diagnostics and therapy. Further research is needed to develop miRNA-based diagnostics and treatments.

Radiation therapy for stage IIA/IIB seminomas: Back to the future?

Seminoma is a highly curable disease; therefore, long-term morbidity of oncological treatment represents a crucial stake. In view of the considerable advances made in radiotherapy in the past decade, we aim to shed light on current and future strategies that hold promises for the management of stage II seminoma.

A Unique Case of Bilateral Testicular Tumours: Nonseminomatous Germ Cell Tumour and Contralateral Spermatocytic Tumour 27 Years Apart

INTRODUCTION

Bilateral testicular tumours occur in 3-5% of all cases with testicular neoplasms. In the majority of cases, histology of the two new growths is identical. The time interval between the two neoplastic events rarely exceeds 10 years.

CASE PRESENTATION

A 29-year-old man of Caucasian descent underwent right-sided orchiectomy for a nonseminomatous germ cell tumour (GCT). Postoperatively, he received adjuvant chemotherapy with 2 cycles of a cisplatin based regimen for clinical stage 1 disease. Twenty-seven years later when aged 56 years, he developed a lump in the left testis. Serum tumour markers including microRNA-371a-3p were within normal limits. Orchiectomy was performed. Histology revealed a spermatocytic tumour with positive stainings of SALL4, NUT, and CD117. No germ cell neoplasia in situ (GCNis) was detected in the tumour-surrounding tissue.

CONCLUSION

Histogenetically, testicular GCTs are thought to derive from the precursor GCNis, while spermatocytic tumours directly derive from adult spermatogonia. This case is exceptional, firstly because of the very long interval of 27 years between the two neoplastic events, and secondly because of the unprecedented occurrence of two testicular neoplasms with different pathogenetic origins in 1 individual patient.

The Role of miRNA in Testicular Cancer: Current Insights and Future Perspectives

Background and Objectives: Despite advancements in the diagnosis and treatment of testicular germ cell tumours (TGTCs), challenges persist in identifying reliable biomarkers for early detection and precise disease management. This narrative review addresses the role of microRNAs (miRNAs) as potential diagnostic tools and therapeutic targets in the treatment of TGCTs. Materials and Methods: Three databases (PubMed®, Web of Science™, and Scopus®) were queried for studies investigating the utility of miRNA as diagnostic tools, assessing their prognostic significance, and evaluating their potential to guide TGCT treatment. Different combinations of the following keywords were used, according to a free-text protocol: "miRNA", "non-coding RNA", "small RNA", "Testicular Cancer", "seminomatous testicular germ cell", "non-seminomatous testicular germ cell". Results: The potential of miRNAs as possible biomarkers for a non-invasive diagnosis of TGCT is appealing. Their integration into the diagnostic pathway for TGCT patients holds the potential to enhance the discriminative power of conventional serum tumour markers (STMs) and could expedite early diagnosis, given that miRNA overexpression was observed in 50% of GCNIS cases. Among miRNAs, miR-371a-3p stands out with the most promising evidence, suggesting its relevance in the primary diagnosis of TGCT, particularly when conventional STMs offer limited value. Indeed, it demonstrated high specificity (90-99%) and sensitivity (84-89%), with good positive predictive value (97.2%) and negative predictive value (82.7%). Furthermore, a direct relationship between miRNA concentration, disease burden, and treatment response exists, regardless of disease stages. The initial evidence of miRNA decrease in response to surgical treatment and systemic chemotherapy has been further supported by more recent results suggesting the potential utility of this tool not only in evaluating treatment response but also in monitoring residual disease and predicting disease relapse. Conclusions: MiRNAs could represent a reliable tool for accurate diagnosis and disease monitoring in the treatment of TGCT, providing more precise tools for early detection and treatment stratification. Nevertheless, well-designed clinical trials and comprehensive long-term data are needed to ensure their translation into effective clinical tools.

Epigenetic Factors and ncRNAs in Testicular Cancer

Testicular cancer is the most prevalent tumor among males aged 15 to 35, resulting in a significant number of newly diagnosed cases and fatalities annually. Non-coding RNAs (ncRNAs) have emerged as key regulators in various cellular processes and pathologies, including testicular cancer. Their involvement in gene regulation, coding, decoding, and overall gene expression control suggests their potential as targets for alternative treatment approaches for this type of cancer. Furthermore, epigenetic modifications, such as histone modifications, DNA methylation, and the regulation by microRNA (miRNA), have been implicated in testicular tumor progression and treatment response. Epigenetics may also offer critical insights for prognostic evaluation and targeted therapies in patients with testicular germ cell tumors (TGCT). This comprehensive review aims to present the latest discoveries regarding the involvement of some proteins and ncRNAs, mainly miRNAs and lncRNA, in the epigenetic aspect of testicular cancer, emphasizing their relevance in pathogenesis and their potential, given the fact that their specific expression holds promise for prognostic evaluation and targeted therapies.

MicroRNA-profiling of miR-371~373- and miR-302/367-clusters in serum and cerebrospinal fluid identify patients with intracranial germ cell tumors

PURPOSE

Intracranial germ cell tumors (iGCT) comprise germinoma and non-germinoma. Their diagnosis predominantly relies on biopsy as only one-fifth of patients present with elevated biomarkers (AFP/ß-HCG) in serum or cerebrospinal fluid (CSF). MicroRNAs (miR/miRNA) have emerged as non-invasive biomarkers in extracranial GCT and may potentially facilitate non-invasive diagnosis in iGCT.

METHODS

We analyzed eight miRNAs in serum and CSF from the miR-371~373- and miR-302/367-clusters and four miRNAs differentially expressed in iGCT tissue (miR-142-5p/miR-146a-5p/miR-335-5p/miR-654-3p) from eight iGCT patients (age 10-33 years) and 12 control subjects by pre-amplified RT-qPCR. MiR-30b-5p (serum) and miR-204-5p (CSF) acted as reference genes. ΔCt-values were expressed as [Formula: see text] after standardization against controls.

RESULTS

Between iGCT and control patients' serum ΔCt-values of miR-371a-3p (p = 0.0159), miR-372-3p (p= 0.0095, miR-367 (p = 0.0190), miR-302a (p = 0.0381) and miR-302d-3p (p = 0.0159) differed significantly. Discriminatory pattern in CSF was similar to serum as miR-371a (p = 0.0286), miR-372-3p (p = 0.0028), miR-367-3p (p = 0.0167) and miR-302d-3p (p = 0.0061) distinguished between patients and controls. Abundant [Formula: see text] levels of each of these miRNAs were found across all serum and CSF samples including biomarker-negative patients.

CONCLUSION

With the largest data set so far, we underline the suitability of miR-371a, miR-372, miR-367 and miR-302d in serum and CSF for diagnosis of iGCT, particularly in biomarker-negative germinoma. Diagnosis of iGCT by miRNA analysis is a feasible and valid approach, particularly as serum can be readily obtained by a less invasive procedure. MiRNA analysis may discriminate iGCT from other tumors with similar radiological findings and may allow to monitor response to therapy as well as early relapse during follow-up.

Impact of differing methodologies for serum miRNA-371a-3p assessment in stage I testicular germ cell cancer recurrence

Introduction

Current evidence shows that serum miR-371a-3p can identify disease recurrence in testicular germ cell tumour (TGCT) patients and correlates with tumour load. Despite convincing evidence showing the advantages of including miR-371a-3p testing to complement and overcome the classical serum tumour markers limitations, the successful introduction of a serum miRNA based test into clinical practice has been impeded by a lack of consensus regarding optimal methodologies and lack of a universal protocol and thresholds. Herein, we investigate two quantitative real-time PCR (qRT-PCR) based pipelines in detecting disease recurrence in stage I TGCT patients under active surveillance, and compare the sensitivity and specificity for each method.

Methods

Sequential serum samples collected from 33 stage I TGCT patients undergoing active surveillance were analysed for miR-371a-3p via qRT-PCR with and without an amplification step included.

Results

Using a pre-amplified protocol, all known recurrences were detected via elevated miR-371a-3p expression, while without pre-amplification, we failed to detect recurrence in 3/10 known recurrence patients. For pre-amplified analysis, sensitivity and specificity was 90% and 94.4% respectively. Without amplification, sensitivity dropped to 60%, but exhibited 100% specificity.

Discussion

We conclude that incorporating pre-amplification increases sensitivity of miR-371a-3p detection, but produces more false positive results. The ideal protocol for quantification of miR-371a-3p still needs to be determined. TGCT patients undergoing active surveillance may benefit from serum miR-371a-3p quantification with earlier detection of recurrences compared to current standard methods. However, larger cross-institutional studies where samples are processed and data is analysed in a standardised manner are required prior to its routine clinical implementation.

The Role of microRNAs in the Gonocyte Theory as Target of Malignancy: Looking for Potential Diagnostic Biomarkers

Some pediatric patients with cryptorchidism preserve cells with gonocyte characteristics beyond their differentiation period, which could support the theory of the gonocyte as a target for malignancy in the development of testicular neoplasia. One of the key molecules in gonocyte malignancy is represented by microRNAs (miRNAs). The goal of this review is to give an overview of miRNAs, a class of small non-coding RNAs that participate in the regulation of gene expression. We also aim to review the crucial role of several miRNAs that have been further described in the regulation of gonocyte differentiation to spermatogonia, which, when transformed, could give rise to germ cell neoplasia in situ, a precursor lesion to testicular germ cell tumors. Finally, the potential use of miRNAs as diagnostic and prognostic biomarkers in testicular neoplasia is addressed, due to their specificity and sensitivity compared to conventional markers, as well as their applications in therapeutics.

MiRNA biomarkers in cancers of the male reproductive system: are we approaching clinical application?

BACKGROUND

Specific cancer types face specific clinical management challenges. Owing to their stability, robustness and fast, easy, and cost-effective detection, microRNAs (miRNAs) are attractive candidate biomarkers to the clinic.

OBJECTIVES

Based on a comprehensive review of the relevant literature in the field, we explore the potential of miRNAs as biomarkers to answer relevant clinical dilemmas inherent to cancers of the male reproductive tract (prostate (PCa), testis (TGCTs) and penis (PeCa)) and identify some of the challenges/limitations hampering their widely application.

RESULTS AND DISCUSSION

We conclude that the use of miRNAs as biomarkers is at different stages for these distinct cancer types. While for TGCTs, miRNA-371a-3p is universally accepted to fill in important clinicals gaps and is moving fast towards clinical implementation, for PCa almost no overlap of miRNAs exists between studies, denoting the absence of a consistent miRNA biomarker, and for PeCa the field of miRNAs has just recently started, with only a few studies attempting to explore their clinical usefulness.

CONCLUSION

Technological advances influencing miRNA detection and quantification will be instrumental to continue to move forward with implementation of miRNAs in the clinic as biomarkers for non-invasive diagnosis, risk stratification, treatment monitoring and follow-up. This article is protected by copyright. All rights reserved.

Associations of serum levels of microRNA-371a-3p (M371) with risk factors for progression in nonseminomatous testicular germ cell tumours clinical stage 1

Purpose

Lymphovascular invasion (LV1) and presence of > 50% embryonal carcinoma (> 50% EC) represent risk factors for progression in patients with clinical stage 1 (CS1) nonseminomatous (NS) testicular germ cell tumours. As serum levels of microRNA-371a-3p (M371) are capable of detecting small amounts of GCT, we evaluated if LV1 and > 50% EC are associated with M371 levels.

Methods

M371 serum levels were measured postoperatively in 153 NS CS1 patients and both pre- and postoperatively in 131 patients. We registered the following factors: age, tumour size, LV status, > 50% EC, teratoma in primary, preoperative elevation of classical tumour markers. M371 expression was compared among subgroups. The ability of M371 to predict LV1 was calculated by receiver operating characteristics (ROC) curves. Multiple regression analysis was used to look for associations of M371 levels with other factors.

Results

Postoperatively elevated M371 levels were found in 29.4% of the patients, but were neither associated with LV status nor with > 50% EC. Likewise, relative decrease of M371 was not associated. ROC analysis of postoperative M371 levels revealed an AUC of 0.5 for the ability to predict LV1 while preoperative M371 had an AUC of 0.732. Multiple regression analysis revealed significant associations of preoperative M371 levels with LV status (p = 0.003), tumour size (p = 0.001), > 50% EC (p = 0.004), and teratoma component (p = 0.045).

Conclusion

Postoperatively elevated M371 levels are not associated with risk factors for progression in NS CS1 patients. However, the significant association of preoperative M371 expression with LV1 deserves further evaluation.

Combining Hypermethylated RASSF1A Detection Using ddPCR with miR-371a-3p Testing: An Improved Panel of Liquid Biopsy Biomarkers for Testicular Germ Cell Tumor Patients

The classical serum tumor markers used routinely in the management of testicular germ cell tumor (TGCT) patients-alpha fetoprotein (AFP) and human chorionic gonadotropin (HCG)-show important limitations. miR-371a-3p is the most recent promising biomarker for TGCTs, but it is not sufficiently informative for detection of teratoma, which is therapeutically relevant. We aimed to test the feasibility of hypermethylated RASSF1A (RASSF1AM) detected in circulating cell-free DNA as a non-invasive diagnostic marker of testicular germ cell tumors, combined with miR-371a-3p. A total of 109 serum samples of patients and 29 sera of healthy young adult males were included, along with representative cell lines and tumor tissue samples. We describe a novel droplet digital polymerase chain reaction (ddPCR) method for quantitatively assessing RASSF1AM in liquid biopsies. Both miR-371a-3p (sensitivity = 85.7%) and RASSF1AM (sensitivity = 86.7%) outperformed the combination of AFP and HCG (sensitivity = 65.5%) for TGCT diagnosis. RASSF1AM detected 88% of teratomas. In this representative cohort, 14 cases were negative for miR-371a-3p, all of which were detected by RASSF1AM, resulting in a combined sensitivity of 100%. We have described a highly sensitive and specific panel of biomarkers for TGCT patients, to be validated in the context of patient follow-up and detection of minimal residual disease.

Improving outcomes in germ cell cancers using miRNA

Owing to advances in treatment paradigms across the last five decades, testicular cancer is now eminently curable. However, current serum tumour and imaging biomarkers lack adequate sensitivity, specificity, and predictive value. Subsequently, their utility in detecting active malignancy and informing treatment decisions is minimal in a large proportion of men with testicular cancer. Micro-ribonucleic acids (miRNA), pertinently miR-371a-3p, offer a new tool, which based on early data, appears to fill many of the gaps that existing biomarkers leave. This paper reviews the evolution of the technology, potential limitations, and discusses the clinical relevance of miRNA as it moves towards the clinic.

Circulating MicroRNAs, the Next-Generation Serum Biomarkers in Testicular Germ Cell Tumours: A Systematic Review

CONTEXT

Clinical management of testicular germ cell tumours (GCTs) is hampered by low sensitivity and specificity of the biomarkers currently in use. Circulating microRNAs (miRs) might offer the potential to address areas of unmet clinical need.

OBJECTIVE

To systematically evaluate the evidence for clinical applications of serum levels of miR302/367 and miR371-3 in adult testicular GCTs in terms of primary diagnosis, various clinical scenarios, and the costs of clinical implementation.

EVIDENCE ACQUISITION

We performed a critical review of PubMed/Medline, Embase and the Cochrane Library in January 2021 in accordance with Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement.

EVIDENCE SYNTHESIS

Thirty-one manuscripts addressed miR performance and potential clinical use in testicular GCT. Of these, 23 evaluated the utility in primary diagnosis, seven in early-stage disease, and 13 in metastatic disease, and two addressed the costs of clinical implementation. Of the various miRs studied, miR-371a-3p appears the most useful and potentially the only one that needs to be assayed, with an area under the receiver operating characteristic curve >0.90, sensitivity of 89-96%, and specificity of >90% for both seminoma and nonseminoma, surpassing the classic serum tumour markers. The miRs studied to date are not elevated in cases with teratoma only. Levels of miR-371a-3p correlate with primary tumour mass, clinical stage, and International Germ Cell Cancer Collaborative Group risk groups. Serial measurements mirror treatment efficacy in all clinical stages.

CONCLUSIONS

Circulating miRNA levels, particularly of miR-371a-3p, have potential for incorporation in clinical practice and may aid in clinical decision-making in various clinical scenarios in GCT.

PATIENT SUMMARY

We analysed the current evidence on the usefulness of blood levels of molecules called microRNAs in the management of testicular tumours. The microRNA-371a-3p molecule has better sensitivity and specificity than the markers currently being measured. This new biomarker may soon have a place in clinical practice.

Small RNAs in Seminal Plasma as Novel Biomarkers for Germ Cell Tumors

Simple Summary

Testicular cancer is the most common cancer among young men. It is rarely diagnosed at early stages, being only detected with a highly invasive procedure that presents notable side-effects. Circulating small RNAs have recently been identified as testicular tumor markers, but are unable to diagnose testicular cancer at an early pre-invasive stage. So far, studies have been limited to microRNAs, with other small RNAs remaining unexplored as likely biomarkers. By sequencing all small RNAs in semen samples from men with different stages of testicular cancer and healthy men, we identify signatures predictive of cancer, even at an early stage. Thus, our study provides great potential for non-invasive early diagnosis of testicular cancer. Extensive biological variance in small RNA levels across samples, together with small sample sizes, limit the power to detect single small RNA markers. Hence, larger studies are needed to confirm our findings and deduce their full diagnostic capacity.

Abstract

Circulating miRNAs secreted by testicular germ cell tumors (TGCT) show great potential as novel non-invasive biomarkers for diagnosis of TGCT. Seminal plasma (SP) represents a biofluid closer to the primary site. Here, we investigate whether small RNAs in SP can be used to diagnose men with TGCTs or the precursor lesions, germ cell neoplasia in situ (GCNIS). Small RNAs isolated from SP from men with TGCTs (n = 18), GCNIS-only (n = 5), and controls (n = 25) were sequenced. SP from men with TGCT/GCNIS (n = 37) and controls (n = 22) were used for validation by RT-qPCR. In general, piRNAs were found at lower levels in SP from men with TGCTs. Ten small RNAs were found at significantly (q-value < 0.05) different levels in SP from men with TGCT/GCNIS than controls. Random forests classification identified sets of small RNAs that could detect either TGCT/GCNIS or GCNIS-only with an area under the curve of 0.98 and 1 in ROC analyses, respectively. RT-qPCR validated hsa-miR-6782-5p to be present at 2.3-fold lower levels (p = 0.02) in the SP from men with TGCTs compared with controls. Small RNAs in SP show potential as novel biomarkers for diagnosing men with TGCT/GCNIS but validation in larger cohorts is needed.

Liquid Biopsies in the Clinical Management of Germ Cell Tumor Patients: State-of-the-Art and Future Directions

Liquid biopsies constitute a minimally invasive means of managing cancer patients, entailing early diagnosis, follow-up and prediction of response to therapy. Their use in the germ cell tumor field is invaluable since diagnostic tissue biopsies (which are invasive) are often not performed, and therefore only a presumptive diagnosis can be made, confirmed upon examination of the surgical specimen. Herein, we provide an overall review of the current liquid biopsy-based biomarkers of this disease, including the classical, routinely used serum tumor markers—the promising microRNAs rapidly approaching the introduction into clinical practice—but also cell-free DNA markers (including DNA methylation) and circulating tumor cells. Finally, and importantly, we also explore novel strategies and challenges for liquid biopsy markers and methodologies, providing a critical view of the future directions for liquid biopsy tests in this field, highlighting gaps and unanswered questions.

Expression of miRNA-371a-3p in seminal plasma and ejaculate is associated with sperm concentration

BACKGROUND

The microRNAs of the miR-371-3 cluster are novel serum markers for testicular germ cell tumors. Sporadic reports suggested the expression of this miRNA in semen.

OBJECTIVES

To verify the expression of miR-371a-3p in seminal plasma and unprocessed ejaculate; to compare seminal plasma miRNA levels in germ cell tumors patients with those of controls; to look for an association of miRNA levels with semen quality.

MATERIALS AND METHODS

The miR-371a-3p expression was analyzed with qPCR. The study population consisted of 100 participants: seminal plasma samples from 20 germ cell tumors patients and 30 controls, serum samples from 12 healthy men, ejaculate samples from 38 men undergoing fertility testing.

RESULTS

The seminal plasma miR-371a-3p levels of germ cell tumors patients were not different from controls. The miRNA expression was very low in serum but much higher in seminal plasma. In ejaculate samples, the miRNA expression significantly correlated with sperm concentration and the total sperm count.

DISCUSSION

miR-371-a-3p is present in sperm-containing fluids. Seminal plasma levels cannot be used to distinguish germ cell tumors from controls. The correlation with sperm concentration in ejaculate samples suggests the spermatozoa as possible source of miR-371a-3p production.

CONCLUSION

The miR-371a-3p levels in ejaculate could represent a novel biomarker for the non-invasive evaluation of male infertility.

Report From the International Society of Urological Pathology (ISUP) Consultation Conference on Molecular Pathology of Urogenital Cancers: IV: Current and Future Utilization of Molecular-Genetic Tests for Testicular Germ Cell Tumors

The International Society of Urological Pathology (ISUP) organized a Consultation Conference in March 2019 dealing with applications of molecular pathology in Urogenital Pathology, including testicular tumors (with a focus on germ cell tumors [GCTs]), preceded by a survey among its members to get insight into current practices in testicular germ cell tumor (TGCT) diagnostics and adoption of the ISUP immunohistochemical guidelines published in 2014. On the basis of the premeeting survey, the most commonly used immunomarker panel includes OCT3/4, placental alkaline phosphate, D2-40, SALL4, CD117, and CD30 for GCTs and the documentation of germ cell neoplasia in situ (GCNIS). Molecular testing, specifically 12p copy gain, is informative to distinguish non-GCNIS versus GCNIS related GCTs, and establishing germ cell origin of tumors both in the context of primary and metastatic lesions. Other molecular methodologies currently available but not widely utilized for TGCTs include genome-wide and targeted approaches for specific genetic anomalies, P53 mutations, genomic MDM2 amplification, and detection of the p53 inactivating miR-371a-3p. The latter also holds promise as a serum marker for malignant TGCTs. This manuscript provides an update on the classification of TGCTs, and describes the current and future role of molecular-genetic testing. The following recommendations are made: (1) Presence of GCNIS should be documented in all cases along with extent of spermatogenesis; (2) Immunohistochemical staining is optional in the following scenarios: identification of GCNIS, distinguishing embryonal carcinoma from seminoma, confirming presence of yolk sac tumor and/or choriocarcinoma, and differentiating spermatocytic tumor from potential mimics; (3) Detection of gain of the short arm of chromosome 12 is diagnostic to differentiate between non-GCNIS versus GCNIS related GCTs and supportive to the germ cell origin of both primary and metastatic tumors.

Graded expression of microRNA-371a-3p in tumor tissues, contralateral testes, and in serum of patients with testicular germ cell tumor

Background: Serum levels of microRNA-371a-3p represent a specific tumor marker of testicular germ cell tumors (GCTs) but the origin of circulating miR-371a-3p is not finally resolved. The correlation between miR-levels in tissue and serum is unclear.

Results: MiR-levels in GCT tissue are 399-fold higher than in contralateral testicular tissue and 5843-fold higher than in non-testicular tissue. MiR tissue levels correlate with corresponding serum levels (r² = 0.181). ISH detected miR-371a-3p intracellularly in GCT cells except teratoma. A low expression was also detected in normal testicular germ cells.

Conclusions: Circulating miR-371a-3p is specifically derived from GCT tissue. The miR is present in GCT cells except teratoma. A low expression is also found in normal testicular tissue but not in non-testicular tissue. MiR-371a-3p levels in tissue and serum correlate significantly. This study underscores the usefulness of serum miR-371a-3p as tumor marker of GCT.

Patients and methods: Expression levels of miR-371a-3p were concurrently measured in tissues of GCT, contralateral testes (n = 38), and in serum (n = 36) with real time PCR. For control, 5 healthy testicles and 4 non-testicular tissue samples were examined. MiR-levels were compared using descriptive statistical methods. We also performed in situ hybridization (ISH) of GCT tissue with a probe specific for miR-371a-3p.

Evaluation of Circulating miRNA Biomarkers of Testicular Germ Cell Tumors during Therapy and Follow-up-A Copenhagen Experience

New microRNA-based serum biomarkers (miRNA-367-3p, -371a-3p, -372-3p, and -373-3p) have shown great potential for the detection of testicular germ cell tumors (TGCTs), but few studies have investigated the clinical utility and performance of these tests in treatment monitoring. In this study, circulating miRNA levels were measured, together with serum tumor markers alpha-fetoprotein (AFP), β-subunit of human chorionic gonadotropin (β-HCG) and lactate dehydrogenase (LDH) in 406 consecutive blood samples obtained during the treatment and follow-up of 52 TGCT patients at the Copenhagen University Hospital. After testing three different methods of RNA isolation from peripheral blood and PCR quantification in a subset of samples (n = 15), the best performing setup of targeted isolation of miRNAs inside and outside exosomes was selected to analyze all samples. At primary diagnosis, the miRNAs significantly outperformed the serum tumor markers, with a sensitivity and specificity of 78% and 100% (based on 40 patients), respectively. The picture was not as clear when patient trajectories were investigated, with both positive and negative signals for miRNAs and serum tumor markers. To establish whether measuring miRNAs adds value beyond the primary diagnosis, large prospective clinical trials comparing miRNAs and classical tumor markers during the treatment and follow-up of TGCT patients are needed.

Non-Coding microRNAs as Novel Potential Tumor Markers in Testicular Cancer

Testicular cancer is an important disease with increasing incidence and a high burden of morbidity and mortality in young men worldwide. Histological examination of the testicular tissue after orchiectomy plays an important role alongside patient history, imaging, clinical presentation and laboratory parameters. Surgical procedures and chemotherapeutic treatment provide a high chance of cure in early stages, though some patients in advanced stages belonging to a poor risk group experience cancer-related death. Though conventional serum-based tumor markers, including α-fetoprotein (AFP), the β-subunit of human chorionic gonadotropin (β-hCG), and lactate dehydrogenase (LDH), are useful as prognostic and diagnostic biomarkers, unfortunately, these tumor markers only have a sensitivity of about 60%, and in pure seminoma even lower with about 20%. Therefore, the development of new tumor markers is an important and intensively ongoing issue. The analysis of epigenetic modification and non-coding RNA microRNAs (miRNAs) are carrying most promising potential as tumor markers in future. miRNAs are small RNAs secreted by testicular tumor cells and circulate and be measurable in body fluids. In recent years, miRNAs of the miR-371-373 cluster in particular have been identified as potentially superior tumor markers in testicular cancer patients. Studies showed that miR-371a-3p and miR-302/367 expression significantly differ between testicular tumors and healthy testicular tissue. Several studies including high prospective multi-center trials clearly demonstrated that these miRNAs significantly exceed the sensitivity and specificity of conventional tumor markers and may help to facilitate the diagnosis, follow-up, and early detection of recurrences in testicular cancer patients. In addition, other miRNAs such as miR-223-3p, miR-449, miR-383, miR-514a-3p, miR-199a-3p, and miR-214 will be discussed in this review. However, further studies are needed to identify the value of these novel markers in additional clinical scenarios, including the monitoring in active surveillance or after adjuvant chemotherapy, but also to show the limitations of these tumor markers. The aim of this review is to give an overview on the current knowledge regarding the relevance of non-coding miRNAs as biomarkers in testicular cancer.

Application of miRNAs in the diagnosis and monitoring of testicular germ cell tumours

Testicular germ cell tumours (TGCTs) are the most frequent cancer type in young men and originate from the common precursor germ cell neoplasia in situ (GCNIS). For decades, clinical management of patients with TGCT has relied on classic serum tumour markers: α-fetoprotein, human chorionic gonadotropin subunit-β and lactate dehydrogenase. In the past 10 years, microRNAs have been shown to outperform classic serum tumour markers in the diagnosis of primary tumours and in follow-up monitoring and prediction of relapse. miR-371a-3p is the most consistent marker and exhibits >90% diagnostic sensitivity and specificity in TGCT. However, miR-371a-3p cannot be used to diagnose GCNIS or mature teratoma. Future efforts must technically standardize the microRNA-based methods internationally and introduce miR-371a-3p as a molecular liquid biopsy-based marker for TGCTs in the clinic.

Identification and Validation Model for Informative Liquid Biopsy-Based microRNA Biomarkers: Insights from Germ Cell Tumor In Vitro, In Vivo and Patient-Derived Data

Liquid biopsy-based biomarkers, such as microRNAs, represent valuable tools for patient management, but often do not make it to integration in the clinic. We aim to explore issues impeding this transition, in the setting of germ cell tumors, for which novel biomarkers are needed. We describe a model for identifying and validating clinically relevant microRNAs for germ cell tumor patients, using both in vitro, in vivo (mouse model) and patient-derived data. Initial wide screening of candidate microRNAs is performed, followed by targeted profiling of potentially relevant biomarkers. We demonstrate the relevance of appropriate (negative) controls, experimental conditions (proliferation), and issues related to sample origin (serum, plasma, cerebral spinal fluid) and pre-analytical variables (hemolysis, contaminants, temperature), all of which could interfere with liquid biopsy-based studies and their conclusions. Finally, we show the value of our identification model in a specific scenario, contradicting the presumed role of miR-375 as marker of teratoma histology in liquid biopsy setting. Our findings indicate other putative microRNAs (miR-885-5p, miR-448 and miR-197-3p) fulfilling this clinical need. The identification model is informative to identify the best candidate microRNAs to pursue in a clinical setting.

Genitourinary Tumors: Update on Molecular Biomarkers for Diagnosis, Prognosis and Prediction of Response to Therapy

BACKGROUND

Research of biomarkers in genitourinary tumors goes along with the development of complex emerging techniques ranging from next generation sequencing platforms, applied to archival pathology specimens, cytological samples, liquid biopsies, and to patient-derived tumor models.

METHODS

This contribution is an update on molecular biomarkers for diagnosis, prognosis and prediction of response to therapy in genitourinary tumors. The following major topics are dealt with: Immunological biomarkers, including the microbiome, and their potential role and caveats in renal cell carcinoma, bladder and prostate cancers and testicular germ cell tumors; Tissue biomarkers for imaging and therapy, with emphasis on Prostate-specific membrane antigen in prostate cancer; Liquid biomarkers in prostate cancer, including circulating tumor cell isolation and characterization in renal cell carcinoma, bladder cancer with emphasis on biomarkers detectable in the urine and testicular germ cell tumors; and Biomarkers and economic sustainability.

CONCLUSION

The identification of effective biomarkers has become a major focus in cancer research, mainly due to the necessity of selecting potentially responsive patients in order to improve their outcomes, as well as to reduce the toxicity and costs related to ineffective treatments.

Predicting Gonadal Germ Cell Cancer in People with Disorders of Sex Development; Insights from Developmental Biology

The risk of gonadal germ cell cancer (GGCC) is increased in selective subgroups, amongst others, defined patients with disorders of sex development (DSD). The increased risk is due to the presence of part of the Y chromosome, i.e., GonadoBlastoma on Y chromosome GBY region, as well as anatomical localization and degree of testicularization and maturation of the gonad. The latter specifically relates to the germ cells present being at risk when blocked in an embryonic stage of development. GGCC originates from either germ cell neoplasia in situ (testicular environment) or gonadoblastoma (ovarian-like environment). These precursors are characterized by presence of the markers OCT3/4 (POU5F1), SOX17, NANOG, as well as TSPY, and cKIT and its ligand KITLG. One of the aims is to stratify individuals with an increased risk based on other parameters than histological investigation of a gonadal biopsy. These might include evaluation of defined susceptibility alleles, as identified by Genome Wide Association Studies, and detailed evaluation of the molecular mechanism underlying the DSD in the individual patient, combined with DNA, mRNA, and microRNA profiling of liquid biopsies. This review will discuss the current opportunities as well as limitations of available knowledge in the context of predicting the risk of GGCC in individual patients.

Cellular origin of microRNA-371a-3p in healthy males based on systematic urogenital tract tissue evaluation

BACKGROUND

The microRNA-371a-3p (miR-371a-3p) has been reported to be an informative liquid biopsy (serum and plasma) molecular biomarker for both diagnosis and follow-up of patients with a malignant (testicular) germ cell tumor ((T)GCT). It is expressed in all histological cancer elements, with the exception of mature teratoma. However, normal testis, semen, and serum of males with a disrupted testicular integrity without a TGCT may contain miR-371a-3p levels above threshold, of which the cellular origin is unknown.

OBJECTIVES

Therefore, a series of relevant tissues (frozen and formalin-fixed paraffin-embedded (FFPE), when available) from the complete male urogenital tract (i.e., kidney to urethra and testis to urethra) and semen was investigated for miR-371a-3p levels using targeted quantitative RT-PCR (qRT-PCR).

MATERIALS AND METHODS

In total, semen of males with normospermia (n = 11) and oligospermia (n = 3) was investigated, as well as 88 samples derived from 32 different patients. The samples represented one set of tissues related to the entire male urogenital tract (11 anatomical locations), three sets for 10 locations, and four sets for six locations.

RESULTS

All testis parenchyma (n = 17) cases showed low miR-371a-3p levels. Eight out of 14 (57%) semen samples showed detectable miR-371a-3p levels, irrespective of the amount of motile spermatozoa, but related to sperm concentration and matched Johnsen score (Spearman's rho correlation coefficient 0.849 and 0.871, p = 0.000, respectively). In all other tissues investigated, miR-371a-3p could not be detected.

DISCUSSION

This study demonstrates that the miR-371a-3p in healthy adult males is solely derived from the germ cell compartment.

CONCLUSIONS

The observation is important in the context of applying miR-371a-3p as molecular liquid biopsy biomarker for diagnosis and follow-up of patients with malignant (T)GCT. Moreover, miR-371a-3p might be an informative seminal biomarker for testicular germ cell composition.

Quantitative PCR Measurement of miR-371a-3p and miR-372-p Is Influenced by Hemolysis

Cell-free microRNAs have been reported as biomarkers for several diseases. For testicular germ cell tumors (GCT), circulating microRNAs 371a-3p and 372-3p in serum and plasma have been proposed as biomarkers for diagnostic and disease monitoring purposes. The most widely used method for quantification of specific microRNAs in serum and plasma is reverse transcriptase real-time quantitative PCR (RT-qPCR) by the comparative Ct-method. In this method one or several reference genes or reference microRNAs are needed in order to normalize and calculate the relative microRNA levels across samples. One of the pitfalls in analysis of microRNAs from serum and plasma is the release of microRNAs from blood cells during hemolysis. This is an important issue because varying degrees of hemolysis are not uncommon in routine blood sampling. Thus, hemolysis must be taken into consideration when working with circulating microRNAs from blood. miR-93-5p, miR-30b-5p, and miR-20a-5p have been reported as reference microRNA in analysis of the miR-371a-373 cluster. We here show how these three microRNAs are influenced by hemolysis. We also propose a new reference microRNA, miR-191-5p, which is relatively stable in serum samples with mild hemolysis. In addition, we show how hemolysis can have effect on the reported microRNA levels in patient samples when these reference microRNAs are used in samples with varying levels of hemolysis.

Human Germ Cell Tumors are Developmental Cancers: Impact of Epigenetics on Pathobiology and Clinic

Current (high throughput omics-based) data support the model that human (malignant) germ cell tumors are not initiated by somatic mutations, but, instead through a defined locked epigenetic status, representative of their cell of origin. This elegantly explains the role of both genetic susceptibility as well as environmental factors in the pathogenesis, referred to as 'genvironment'. Moreover, it could also explain various epidemiological findings, including the rising incidence of this type of cancer in Western societies. In addition, it allows for identification of clinically relevant and informative biomarkers both for diagnosis and follow-up of individual patients. The current status of these findings will be discussed, including the use of high throughput DNA methylation profiling for determination of differentially methylated regions (DMRs) as well as chromosomal copy number variation (CNV). Finally, the potential value of methylation-specific tumor DNA fragments (i.e., XIST promotor) as well as embryonic microRNAs as molecular biomarkers for cancer detection in liquid biopsies will be presented.

Emerging Prognostic Biomarkers in Testicular Germ Cell Tumors: Looking Beyond Established Practice

Testicular germ cell tumors are unique among solid cancers. Historically, this disease was deadly if progressed beyond the stage I. The implementation of cisplatin-based chemotherapy regimens has drastically changed the clinical outcome of metastatic testicular cancer. Several biomarkers were established to refine the prognosis by International Germ Cell Collaborative Group in 1997. Among these, the most significant were primary tumor site; metastatic sites, such as non-pulmonary visceral metastases; and the amplitude of serum tumor markers α-fetoprotein, β-chorionic gonadotropin, and lactate dehydrogenase. Since then, oncology has experienced discoveries of various molecular biomarkers to further refine the prognosis and treatment of malignancies. However, the ability to predict the prognosis and treatment response in germ cell tumors did not improve for many years. Clinical trials with novel targeting agents that were conducted in refractory germ cell tumor patients have proven to have negative outcomes. With the recent advances and developments, novel biomarkers emerge in the field of germ cell tumor oncology. This review article aims to summarize the current knowledge in the research of novel prognostic biomarkers in testicular germ cell tumors.

Testicular cancer

Testicular cancer is the most common malignancy among men between 14 and 44 years of age, and its incidence has risen over the past two decades in Western countries. Both genetic and environmental factors contribute to the development of testicular cancer, for which cryptorchidism is the most common risk factor. Progress has been made in our understanding of the disease since the initial description of carcinoma in situ of the testis in 1972 (now referred to as germ cell neoplasia in situ), which has led to improved treatment options. The combination of surgery and cisplatin-based chemotherapy has resulted in a cure rate of >90% in patients with testicular cancer, although some patients become refractory to chemotherapy or have a late relapse; an improved understanding of the molecular determinants underlying tumour sensitivity and resistance may lead to the development of novel therapies for these patients. This Primer provides an overview of the biology, epidemiology, diagnosis and current treatment guidelines for testicular cancer, with a focus on germ cell tumours. We also outline areas for future research and what to expect in the next decade for testicular cancer.

The Novel Biomarker of Germ Cell Tumours, Micro-RNA-371a-3p, Has a Very Rapid Decay in Patients with Clinical Stage 1

BACKGROUND

Accumulating evidence suggests serum levels of microRNA (miR)-371a-3p to be a novel tumour marker of testicular germ cell tumours (GCTs). Presently, there is only limited information regarding the velocity of decline of serum levels in response to treatment.

PATIENTS AND METHODS

Twenty-four patients with testicular GCT (20 seminoma, 4 nonseminoma, median age 40 years) with clinical stage 1 had measurements of serum levels of miR-371a-3p preoperatively and repeatedly on the following 3 days. Three had additional tests done within 24 h after surgery. Measurement results were analysed using descriptive statistical methods.

RESULTS

Serum levels dropped to 2.62, 1.27, and 0.47% of the preoperative level within 1, 2, and 3 days, respectively. The computed half-life amounts to 3.7-7 h. The velocity of decay is significantly associated with tumour size.

CONCLUSIONS

Serum-levels of miR-371a-3p have a short half-life of less than 12 h. The rapid decay after treatment represents a valuable feature confirming the usefulness of miR-371a-3p as a valuable serum biomarker of GCT.

Accurate primary germ cell cancer diagnosis using serum based microRNA detection (ampTSmiR test)

Multiple studies, including various methods and overall limited numbers of mostly heterogeneous cases, indicate that the level of embryonic stem cell microRNAs (miRs) (e.g. 371a-3p, 372-3p, 373-3p, and 367-3p) are increased in serum at primary diagnosis of almost all testicular germ cell cancer (TGCC). Here we determine the status of three of these miRs in serum samples of 250 TGCC patients, collected at time of primary diagnosis, compared with 60 non-TGCC patients and 104 male healthy donors. The levels of miRs were measured by the robust ampTSmiR test, including magnetic bead-based miR isolation and target specific pre-amplification followed by real-time quantitative PCR (RT-qPCR) detection. Calibration is performed based on the non-human spike-in ath-miR-159a, and normalization on the endogenous control miR-30b-5p. The serum levels of miR-371a-3p, 373-3p, and 367-3p are informative to accurately detect TGCC patients, both seminomas and non-seminomas, at the time of primary diagnosis (p< 0.000). Receiver Operating Characteristic (ROC) analysis demonstrate that the Area Under the Curve (AUC) for miR-371a-3p is 0.951 (being 0.888 for miR-373-3p and 0.861 for miR-367-3p), with a sensitivity of 90%, and a specificity of 86% (positive predictive value of 94% and negative predictive value of 79%). Inclusion of miR-373-3p and 367-3p resulted in a AUC of 0.962, with a 90% sensitivity and 91% specificity. Similar results were obtained using the raw Ct data. Importantly, the results demonstrate that ampTSmiR is not suitable to detect pure teratoma as well as the precursor of TGCC, i.e., Germ Cell Neoplasia In Situ (GCNIS). The largest series evaluated so far, demonstrate that detection of the embryonic stem cell miR-371a-3p, 373-3p and 367-3p is highly informative to diagnose patients with a primary TGCC.

Can germ cell neoplasia in situ be diagnosed by measuring serum levels of microRNA371a-3p?

Purpose

Diagnosing germ cell neoplasia in situ (GCNis) can detect germ cell tumours (GCTs) at the pre-invasive stage. To date, testicular biopsy with the potential of surgical complications is the only way of safely diagnosing GCNis. Recently, microRNAs (miRs) 371-3, and miR 367 were shown to be valuable serum biomarkers of GCTs. We explored the usefulness of these candidate miRs as a marker for GCNis.

Methods

27 patients with GCNis and no concomitant GCT were enrolled. All patients underwent measuring serum levels of miR-371a-3p and miR-367-3p before treatment, 11 had repeat measurement after treatment, 2 also had testicular vein blood examinations. Serum levels were measured by quantitative PCR. In addition, four orchiectomy specimens of patients with GCT were examined immunohistochemically and by in situ hybridization (ISH) with a probe specific for miR-371a-3p to look for the presence of this miR in GCNis cells.

Results

The median serum level of miR-371a-3p was significantly higher in patients with GCNis than in controls, miR-367 levels were not elevated. Overall, 14 patients (51.9%) had elevated serum levels of miR-371a-3p. The highest levels were found in patients with bilateral GCNis. Levels in testicular vein serum were elevated in both of the cases. After treatment, all elevated levels dropped to normal. In two orchiectomy specimens, miR-371a-3p was detected by ISH in GCNis cells.

Conclusions

Measuring miR-371a-3p serum levels can replace control biopsies after treatment of GCNis. In addition, the test can guide clinical decision making regarding the need of testicular biopsy in cases suspicious of GCNis.

microRNA-371a-3p as informative biomarker for the follow-up of testicular germ cell cancer patients

PURPOSE

α-fetoprotein (AFP) and human chorionic gonadotropin subunit beta (B-HCG) are informative serum biomarkers for the primary diagnosis and follow-up of testicular germ cell cancer (TGCC) patients. About 20% of TGCC patients with a non-seminoma (NS) and about 80% with a seminoma (SE) are, however, negative for these biomarkers. Embryonic stem cell microRNAs (miRs) may serve as promising alternative serum biomarkers. Here we investigated a retrospective series of serum samples from selected TGCC patients who developed a relapse in time to test the possible additional value of the serum-based ampTSmiR test compared to the conventional serum-based protein biomarkers for follow-up.

METHODS

We investigated 261 retrospective serum samples of six selected fully evaluated TGCC patients with a proven relapse using the ampTSmiR test for miR-371a-3p, miR-373-3p, and miR-367-3p and compared the results to those of the conventional protein biomarkers.

RESULTS

At primary diagnosis, elevated serum B-HCG, AFP and LDH levels were found to be informative in 4/6, 3/6 and 3/6 patients, respectively. At primary diagnosis the levels of miR-371a-3p and miR-373-3p were elevated in 4/4, and miR-367-3p in 3/4 patients. For two cases no starting serum sample was available for retrospective miR analysis. Residual disease (overlooked by histopathological examination) was detected in one case by miR-371a-3p only. The miR-371a-3p level was increased in one patient two months before detection of an intracranial metastasis. B-HCG was informative in 3/4 and the ampTSmiR test in 4/4 patients with a relapse or residual disease. None of the biomarkers were informative for the detection of residual mature teratoma.

CONCLUSIONS

The ampTSmiR test is more sensitive than the conventional TGCC protein biomarkers for the detection of residual disease and relapse, excluding mature teratoma.

Serum Levels of MicroRNA371a-3p: A Highly Sensitive Tool for Diagnosing and Staging Testicular Germ Cell Tumours: A Clinical Case Series

INTRODUCTION

MicroRNA (miR)371a-3p was suggested to be a sensitive and specific new serum biomarker of germ cell tumours (GCTs); however, its clinical usefulness remains unproven.

PATIENTS, METHODS

In 312 consecutive cases with various testicular diseases, serum levels of miR371a-3p were measured. Measurement results became available only after completion of treatment. Five patients with testicular seminoma were selected for review because of unanticipated clinical courses.

RESULTS

In each two patients, elevated miR levels heralded undetected primary testicular GCT and metastases despite inconclusive radiological findings. In one case, a normal miR371a-3p level correctly pointed to the absence of metastases contrary to clinical assessment. In all cases, knowledge about the miR371a-3p levels would have altered the clinical management.

CONCLUSIONS

These cases highlight the exceptional usefulness of the new GCT biomarker. In contrast to classical markers, miR371a-3p can identify primary testicular GCT. The marker can aid in clinical decision making in cases with ambiguous clinical findings.

A Robust Protocol to Quantify Circulating Cancer Biomarker MicroRNAs

Reverse-transcriptase quantitative PCR (RT-qPCR) is a widely used method for quantifying microRNAs (miRNAs) in cells and tissues. However, the quantification of miRNAs in the circulation presents specific challenges. Here, we describe an optimized protocol using a small amount of input material to assess serum sample quality and quantify levels of a panel of up to 20 miRNAs. This is achieved by multiplexing Taqman miRNA stem-loop primers in the reverse transcription step. An additional multiplexed pre-amplification step is used to increase the sensitivity of the final quantification step, which is carried out using standard Taqman qPCR methodology.

Serum Levels of MicroRNA miR-371a-3p: A Sensitive and Specific New Biomarker for Germ Cell Tumours

BACKGROUND

Clinical management of germ cell tumours (GCTs) relies on monitoring of serum tumour markers. However, the markers α-fetoprotein (AFP), the β-subunit of human chorionic gonadotropin (bHCG), and lactate dehydrogenase (LDH) are expressed in <60% of GCT cases.

OBJECTIVE

To test the utility of the microRNAs (miRNAs) miR-371a-3p, miR-372-3p, miR-373-3p, and miR-367-3p as sensitive and specific GCT serum biomarkers.

DESIGN, SETTING, AND PARTICIPANTS

Serum levels of miRNAs were measured in 166 consecutive patients with GCT before and after treatment and in 106 male controls. In the first 50 consecutive patients, all four miRNAs were measured. In the main study, only the most sensitive miRNA was further analysed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The specificity and sensitivity of the four miRNAs were studied using receiver operating characteristic curves. miRNA sensitivities were compared to those of classical markers. Statistical cross-comparisons of miRNA levels for GCT subgroups and controls were performed at various time points during treatment.

RESULTS AND LIMITATIONS

Overall, miR-371a-3p performed best, with 88.7% sensitivity (95% confidence interval [CI] 82.5-93.3%) and 93.4% specificity (95% CI 86.9-97.3%) and an area under the curve of 0.94, outperforming AFP, bHCG, and LDH (combined sensitivity 50%). According to Kernel density estimation, the sensitivity and specificity were 86.3% and 92.5%, respectively. miR-371a-3p levels dropped to normal after completion of treatment. The miRNA levels correlated with treatment failure and relapse. Teratoma did not express miR-371a-3p.

CONCLUSIONS

The miRNA miR-371a-3p is a specific and sensitive novel serum GCT biomarker that accurately correlates with disease activity. Validation of this test in a large-scale prospective study is needed. PATIENT SUMMARY: miR-371a-3p is a novel serum marker for germ cell tumours that is expressed by 88.7% of patients and thus is far more sensitive and specific than classical serum markers. It correlates with tumour burden and treatment results. Validation in a large patient cohort is needed.