Serum Small RNA Sequencing and miR-375 Assay Do Not Identify the Presence of Pure Teratoma at Postchemotherapy Retroperitoneal Lymph Node Dissection

Serum Levels of MicroRNA-371a-3p for Predicting the Histology of Postchemotherapy Residual Masses of Germ Cell Tumours

BACKGROUND AND OBJECTIVE

Serum levels of microRNA-371a-3p (M371) represent a novel and sensitive biomarker of germ cell tumours (GCTs). This study analysed the utility of M371 to identify viable cancer (VC) in postchemotherapy (pc) residual masses with the underlying goal of avoiding overtreatment.

METHODS

A multicentric, prospective diagnostic study was conducted in 180 GCT patients undergoing pc resection of residual masses. A correlation of M371 measurement results with the histological presence of VC in masses was found. A receiver operating characteristic analysis was performed for exploring the performance characteristics of the test.

KEY FINDINGS AND LIMITATIONS

The sensitivity was found to be 68.9%, specificity 99.3%, area under the curve 0.813, positive predictive value 0.969, and negative predictive value 0.905; sensitivity is significantly associated with the percentage of VC in the mass. In specimens with ≤10% VC, there were 33.3% elevated M371 levels as opposed to 85.7% in specimens with >50% VC. Teratoma and somatic-type malignancy do not express M371. A lack of a central pathological review is a limitation.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The M371 test can identify 68.9% of patients with VC in pc masses. However, cases with <10% VC in the mass may escape detection. Teratoma does not express M371. The test alone cannot correctly identify patients requiring pc surgery, but it may be a tool for scheduling the extent of surgery.

PATIENT SUMMARY

The microRNA-371a-3p (M371) test can identify about two-thirds of patients with viable cancer in residual metastatic masses following chemotherapy for germ cell tumours. Only masses with high percentages of viable cancer cells can be identified, and the histological subtype teratoma remains undetected with the test.

MicroRNAs in Testicular Germ Cell Tumors: The Teratoma Challenge

Testicular germ cell tumors (TGCTs) are relatively common in young men, making accurate diagnosis and prognosis assessment essential. MicroRNAs (miRNAs), including microRNA-371a-3p (miR-371a-3p), have shown promise as biomarkers for TGCTs. This review discusses the recent advancements in the use of miRNA biomarkers in TGCTs, with a focus on the challenges surrounding the noninvasive detection of teratomas. Circulating miR-371a-3p, which is expressed in undifferentiated TGCTs but not in teratomas, is a promising biomarker for TGCTs. Its detection in serum, plasma, and, potentially, cystic fluid could be useful for TGCT diagnosis, surveillance, and monitoring of therapeutic response. Other miRNAs, such as miR-375-3p and miR-375-5p, have been investigated to differentiate between TGCT subtypes (teratoma, necrosis/fibrosis, and viable tumors), which can aid in treatment decisions. However, a reliable marker for teratoma has yet to be identified. The clinical applications of miRNA biomarkers could spare patients from unnecessary surgeries and allow for more personalized therapeutic approaches. Particularly in patients with residual masses larger than 1 cm following chemotherapy, it is critical to differentiate between viable tumors, teratomas, and necrosis/fibrosis. Teratomas, which mimic somatic tissues, present a challenge in differentiation and require a comprehensive diagnostic approach. The combination of miR-371 and miR-375 shows potential in enhancing diagnostic precision, aiding in distinguishing between teratomas, viable tumors, and necrosis. The implementation of miRNA biomarkers in TGCT care could improve patient outcomes, reduce overtreatment, and facilitate personalized therapeutic strategies. However, a reliable marker for teratoma is still lacking. Future research should focus on the clinical validation and standardization of these biomarkers to fully realize their potential.

Application of microRNAs in the diagnosis and monitoring of pediatric germ cell tumors: Kazakh experience

GCT is characterized by specific biochemical markers expression, such as human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP), which are the main tools in the diagnosis and monitoring of GCT treatment. They are expressed in 15-20% of cases of seminoma and in 60-80% of cases of non-seminoma. MicroRNA profiling allows to identify a number of microRNAs that are superior to classical serum tumor markers in the diagnosis of primary tumors, as well as in subsequent monitoring and prediction of recurrence. We analyzed the expression of 9 microRNAs (microRNA clusters 302/367 and 371-373, microRNA375) in the blood serum of 20 children with extracranial GCT at different stages of therapy and showed their usefulness and informativeness in early detection of events. Taking into consideration the high sensitivity and specificity, serum microRNAs 367,371,372,373,302d are of great interest for clinical use in malignant GCT. Significant expression of miR 375-3p was not detected either in malignant GCT or in teratomas.

Detection of Recurrence through microRNA-371a-3p Serum Levels in a Follow-up of Stage I Testicular Germ Cell Tumors in the DRKS-00019223 Study

PURPOSE

Surveillance of clinical stage I (CSI) testicular germ cell tumors (GCT) is hampered by low sensitivity and specificity of current biomarkers for detecting relapses. This study evaluated if serum levels of microRNA371a-3p (M371 test) can: (i) Accurately detect relapses, (ii) detect relapses earlier than conventional technology, and (iii) if elevated postoperative M371 levels may predict relapse.

EXPERIMENTAL DESIGN

In a multicentric setting, 258 patients with testicular CSI GCT were prospectively followed by surveillance for a median time of 18 months with serial measurements of serum M371 levels, in addition to standard diagnostic techniques. Diagnostic characteristics of M371 for detecting relapses were calculated using ROC curve analysis.

RESULTS

Thirty-nine patients recurred (15.1%), all with elevated M371 levels; eight without relapse had elevations, too. The test revealed the following characteristics: area under the ROC curve of 0.993, sensitivity 100%, specificity 96.3%, positive predictive value 83%, negative predictive value 100%. Earlier relapse detection with the test was found in 28%, with non-significant median time gain to diagnosis. Postoperative M371 levels did not predict future relapse.

CONCLUSIONS

The sensitivity and specificity of the M371 test for detecting relapses in CSI GCTs are much superior to those of conventional diagnostics. However, post-orchiectomy M371 levels are not predictive of relapse, and there is no significant earlier relapse detection with the test. In all, there is clear evidence for the utility of the M371 test for relapse detection suggesting it may soon be ready for implementation into routine follow-up schedules for patients with testicular GCT.

MicroRNAs for detecting occult genitourinary cancer

PURPOSE OF REVIEW

Genitourinary (GU) malignancies are a real burden in global health worldwide. Each model has its own clinical challenges, and the early screening and/or detection of occult cancer in follow-up is transversal to all of them. MicroRNAs (miRNAs) have been proposed as minimally invasive liquid biopsy cancer biomarkers, due to their stability and low degradation.

RECENT FINDINGS

The different GU tumor models are in different stages concerning miRNAs as biomarkers for cancer detection. Testicular germ cell tumors (TGCTs) already have a specific defined target, miR-371a-3p, that has shown high sensitivity and specificity in different clinical settings, and is now in final stages of preanalytical testing before entering the clinic. The other GU malignancies are in a different stage, with many liquid biopsy studies (both in urine and plasma/serum) being currently performed, but there is not an agreeable miRNA or set of miRNAs that is ready to follow the footsteps of miR-371a-3p in TGCTs.

SUMMARY

Further studies with proper molecular characterization of miRNA profiles of GU malignancies and standardization of sampling, biobanking and formal analysis may aid in the advance and choosing of specific target sets to be used for occult cancer detection.

Molecular Biomarkers With Potential Clinical Application in Testicular Cancer

Testicular germ cell tumors (TGCTs) and sex cord-stromal tumors (SCSTs) are the most common testicular neoplasms. The morphologic spectrum of such tumors is wide, with several histologic subtypes within each group. Testicular tumors often represent a diagnostic challenge, requiring proper identification of their biologic potential for accurate risk stratification and selection of therapy. In the era of precision medicine, molecular biomarkers are increasingly assuming a critical role in the management of patients with cancer. Given the overall rarity of certain types of testicular neoplasms, progress in biomarker research has been relatively slow. However, in recent years, we have witnessed a multitude of important contributions, including both tissue-based and liquid biopsy biomarkers, stemming from important discoveries of tumor pathobiology, accurate histopathological analysis, multi-institutional studies, and genome-wide molecular analyses of specific tumor subtypes. In this review, we provide an overview of the progress in molecular biomarkers of TGCTs and SCSTs, focusing on those with greatest potential for clinical application. In TGCTs, developmental biology has been the key to understanding these tumors and identifying clinically useful biomarkers (from classical serum tumor markers to pluripotency factors and circulating microRNAs of the 371-373 cluster). For SCSTs, studies have focused on tissue biomarkers only, and genome-wide investigations have recently contributed to a better understanding of rare phenotypes and the aggressive biological behavior of some tumors within this nosologic category. Several new biomarkers are moving toward clinical implementation in this field. Therefore, the practicing pathologist should be aware of their strengths and limitations in order to utilize them properly and maximize their clinical benefits.

MicroRNA-371a-3p-The Novel Serum Biomarker in Testicular Germ Cell Tumors

INTRODUCTION

Testicular germ cell tumors (TGCTs) are a paradigm for the use of serum tumor markers in clinical management. However, conventional markers such as alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (hCG), and lactate dehydrogenase (LDH) have quite limited sensitivities and specificities. Within the last decade, the microRNA-371a-3p (miR371) emerged as a possible new biomarker with promising features.

AREAS COVERED

This review covers the typical features as well as possible clinical applications of miR371 in TGCT patients, such as initial diagnosis, therapy monitoring, and follow-up. Additionally, technical issues are discussed.

EXPERT OPINION

With a sensitivity of around 90% and specificity >90%, miR371 clearly outperforms the classical serum tumor markers in TGCTs. The unique features of the test involve the potential of modifying recent standards of care in TGCT. In particular, miR371 is expected to aid clinical decision-making in scenarios such as discriminating small testicular TGCT masses from benign ones prior to surgery, assessing equivocal lymphadenopathies, and monitoring chemotherapy results. Likewise, it is expected to make follow-up easier by reducing the intensity of examinations and by sparing imaging procedures. Overall, the data presently available are promising, but further prospective studies are required before the test can be implemented in standard clinical care.

Novel approaches to redesign surveillance strategies following orchiectomy for localized testicular cancer: a narrative review

Background and Objective

Surveillance is the preferred management strategy for most men with clinical stage I testicular cancer after orchiectomy. However, frequent office visits, imaging tests, and laboratory studies place a significant burden on patients, which may contribute to poor compliance with guideline-recommended surveillance regimens. Identifying strategies to overcome these barriers may help improve quality of life, reduce costs, and improve adherence for patients. We reviewed evidence for three strategies that may help with surveillance redesign: telemedicine, implementing microRNA (miRNA) as a biomarker, and novel imaging protocols.

Methods

A web-based literature search for novel imaging strategies, diagnostic utility of miRNA, and telehealth as they relate to early-stage testicular germ cell cancer was completed during the month of August 2022. We focused our search on contemporary PubMed-indexed and Google Scholar-registered manuscripts written in English. Supportive data sourced from current guideline statements were also included. Evidence was compiled for narrative review.

Key Content and Findings

Telemedicine is a safe and acceptable platform for urologic cancer follow-up care, but it requires further study specifically among men with testicular cancer. Access to care may either be improved or reduced depending on system- and patient-level characteristics and should be implemented with this in mind. miRNA may potentially be a helpful biomarker for men with localized disease, but further research on diagnostic accuracy and marker kinetics are needed before implementing it into routine surveillance strategies or using it to deviate from long-standing surveillance regiments. Novel imaging strategies with less frequent imaging and the use of magnetic resonance imaging (MRI) instead of computed tomography (CT) appear to be non-inferior in clinical trials. However, use of MRI requires expert radiologist availability and may be more costly with a lower ability to detect small, early recurrences when used in routine practice.

Conclusions

Using telemedicine, integrating miRNA as a tumor marker, and adopting less intensive imaging strategies may improve guideline-concordant surveillance for men with localized testicular cancer. Future studies are needed to assess the risks and benefits of using these novel approaches separately or together.

Differentially expressed messenger RNA/proteins can distinguish teratoma from necrosis in postchemotherapy retroperitoneal lymph node dissection tissue

BACKGROUND

Before postchemotherapy retroperitoneal lymph node dissection (pcRPLND), in patients with metastasized germ cell tumors (GCTs), those harboring necrosis (NEC) cannot be distinguished from those who have teratoma (TER), resulting in relevant overtreatment, whereas microRNA-371a-3p may be predictive for viable GCT. The purpose of this study was to explore messenger RNA (mRNA) and proteins to distinguish TER from NEC in pcRPLND tissue.

METHODS

The discovery cohort consisted in total of 48 patients, including 16 each with TER, viable GCT, and NEC. Representative areas were microdissected. A NanoString panel and proteomics were used to analyze 770 genes and >5000 proteins. The most significantly and differentially expressed combination of both parameters, mRNA and its associated protein, between TER and NEC was validated using immunohistochemistry (IHC) in an independent validation cohort comprising 66 patients who were not part of the discovery cohort.

RESULTS

The authors observed that anterior gradient protein 2 homolog (AGR2) and keratin, type I cytoskeletal 19 (KRT19) were significantly differentially expressed in TER versus NEC in mRNA and protein analyses (proteomics). The technical validation using IHC was successful in the same patients. These proteins were further validated by IHC in the independent patient cohort and exhibited significantly higher levels in TER versus NEC (p < .0001; area under the curve, 1.0; sensitivity and specificity, 100% each).

CONCLUSIONS

The current study demonstrated that KRT19 and AGR2 mRNA and protein are overexpressed in TER versus NEC in pcRPLND tissue and might serve as a future diagnostic target to detect TER, for instance, by functional imaging, to avoid overtreatment.

PLAIN LANGUAGE SUMMARY

The proteins and the corresponding genes called AGR2 and KRT19 can differentiate between teratoma and necrosis in remaining tumor masses after chemotherapy in patients who have metastasized testicular cancer. This may be a way to improve presurgical diagnostics and to reduce the current overtreatment of patients with necrosis only, who could be treated sufficiently by surveillance.

Integrated Microarray-Based Data Analysis of miRNA Expression Profiles: Identification of Novel Biomarkers of Cisplatin-Resistance in Testicular Germ Cell Tumours

Testicular germ cell tumours (TGCTs) are the most common solid malignancy among young men, and their incidence is still increasing. Despite good curability with cisplatin (CDDP)-based chemotherapy, about 10% of TGCTs are non-responsive and show a chemoresistant phenotype. To further increase TGCT curability, better prediction of risk of relapse and early detection of refractory cases is needed. Therefore, to diagnose this malignancy more precisely, stratify patients more accurately and improve decision-making on treatment modality, new biomarkers are still required. Numerous studies showed association of differential expressions of microRNAs (miRNAs) with cancer. Using microarray analysis followed by RT-qPCR validation, we identified specific miRNA expression patterns that discriminate chemoresistant phenotypes in TGCTs. Comparing CDDP-resistant vs. -sensitive TGCT cell lines, we identified miR-218-5p, miR-31-5p, miR-125b-5p, miR-27b-3p, miR-199a-5p, miR-214-3p, let-7a and miR-517a-3p as significantly up-regulated and miR-374b-5p, miR-378a-3p, miR-20b-5p and miR-30e-3p as significantly down-regulated. In patient tumour samples, we observed the highest median values of relative expression of miR-218-5p, miR-31-5p, miR-375-5p and miR-517a-3p, but also miR-20b-5p and miR-378a-3p, in metastatic tumour samples when compared with primary tumour or control samples. In TGCT patient plasma samples, we detected increased expression of miR-218-5p, miR-31-5p, miR-517a-3p and miR-375-5p when compared to healthy individuals. We propose that miR-218-5p, miR-31-5p, miR-375-5p, miR-517-3p, miR-20b-5p and miR-378a-3p represent a new panel of biomarkers for better prediction of chemoresistance and more aggressive phenotypes potentially underlying metastatic spread in non-seminomatous TGCTs. In addition, we provide predictions of the targets and functional and regulatory networks of selected miRNAs.

Biomarkers of disease recurrence in stage I testicular germ cell tumours

Stage I testicular cancer is a disease restricted to the testicle. After orchiectomy, patients are considered to be without disease; however, the tumour is prone to relapse in ~4-50% of patients. Current predictive markers of relapse, which are tumour size and invasion to rete testis (in seminoma) or lymphovascular invasion (in non-seminoma), have limited clinical utility and are unable to correctly predict relapse in a substantial proportion of patients. Adjuvant therapeutic strategies based on available biomarkers can lead to overtreatment of 50-85% of patients. Discovery and implementation of novel biomarkers into treatment decision making will help to reduce the burden of adjuvant treatments and improve patient selection for adjuvant therapy.

A meta-analysis of clinicopathologic features that predict necrosis or fibrosis at post-chemotherapy retroperitoneal lymph node dissection in individuals receiving treatment for non-seminoma germ cell tumours

Purpose

Post-chemotherapy retroperitoneal lymph node dissection (pcRPLND) for residual nodal masses is a critical component of care in metastatic testicular germ cell tumour (GCT). However, the procedure is not of therapeutic value in up to 50% of individuals in whom histopathology demonstrates post-treatment necrosis or fibrosis alone. Improved diagnostic tools and clinicopathologic features are needed to separate individuals who benefit from pcRPLND and avoid surgery in those who do not.

Methods

A prospectively registered meta-analysis of studies reporting clinicopathologic features associated with teratoma, GCT and/or necrosis/fibrosis at pcRPLND for metastatic non-seminoma GCT (NSGCT) was undertaken. We examined the effect of various clinicopathologic factors on the finding of necrosis/fibrosis at pcRPLND. The log odds ratios (ORs) of each association were pooled using random-effects models.

Results

Using the initial search strategy, 4,178 potentially eligible abstracts were identified. We included studies providing OR relating to clinicopathologic factors predicting pcRPLND histopathology, or where individual patient-level data were available to permit the calculation of OR. A total of 31 studies evaluating pcRPLND histopathology in 3,390 patients were eligible for inclusion, including two identified through hand-searching the reference lists of eligible studies. The following were associated with the presence of necrosis/fibrosis at pcRPLND: absence of teratomatous elements in orchidectomy (OR 3.45, 95% confidence interval [CI] 2.94-4.17); presence of seminomatous elements at orchidectomy (OR 2.71, 95% CI 1.37-5.37); normal pre-chemotherapy serum bHCG (OR 1.96, 95% CI 1.62-2.36); normal AFP (OR 3.22, 95% CI 2.49–4.15); elevated LDH (OR 1.72, 95% CI 1.37-2.17); >50% change in mass during chemotherapy (OR 4.84, 95% CI 3.94-5.94); and smaller residual mass size (<2 cm versus >2 cm: OR 3.93, 95% CI 3.23-4.77; <5 cm versus >5 cm: OR 4.13, 95% CI 3.26-5.23).

Conclusions

In this meta-analysis, clinicopathologic features helped predict the presence of pcRPLND necrosis/fibrosis. Collaboration between centres that provide individual patient-level data is required to develop and validate clinical models and inform routine care to direct pcRPLND to individuals most likely to derive benefits.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021279699

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.

Predictive capacity of a miRNA panel in identifying teratoma in post-chemotherapy consolidation surgeries

Objectives

To investigate the utility of a novel serum miRNA biomarker panel to distinguish teratoma from nonmalignant necrotic/fibrotic tissues or nonviable tumours in patients with NSGCT undergoing post-chemotherapy consolidation surgery.

Patients and methods

We prospectively collected pre-surgical serum samples from 22 consecutive testicular NSGCT patients with residual NSGCT after chemotherapy undergoing post-chemotherapy consolidation surgery. We measured serum miRNA expression of four microRNAs (miRNA-375, miRNA-200a-3p, miRNA-200a-5p and miRNA-200b-3p) and compared with pathologic findings at time of surgery. Receiver operating characteristic (ROC) curves were performed to assess the ability of these miRNA to differentiate between teratoma and necrosis or viable malignancy.

Results

Twenty-two patients with NSGCT were split into two groups based on pathology at time of post-chemotherapy consolidation surgery (teratoma group vs. necrosis/fibrosis/viable tumour group, i.e., NFVT). Patients with teratoma were older at diagnosis compared with those patients with NFVT (median age 28.7 vs. 23.9). Patients with NFVT were more likely to have embryonal carcinoma in their primary tumour (81.8% vs. 27.3%; p = 0.01). The majority of patients in both groups were stage III (63.6% vs. 72.7%). In this analysis, none of the miRNAs had good sensitivity or specificity to predict teratoma. There was no significant association between the expression levels of the miRNAs and the presence of teratoma. There was no statistically significant correlation between any of the miRNAs and teratoma size.

Conclusion

This novel miRNA panel (miRNA-375, miRNA-200a-3p, miRNA-200a-5p and miRNA-200b-3p) did not distinguish teratoma from nonmalignant necrotic/fibrotic tissues or nonviable tumours in patients with NSGCT undergoing post-chemotherapy consolidation surgery.

The utility of cfDNA in TGCT patient management: a systematic review

Background:

Testicular germ cell tumors (TGCTs) are the most common young male malignancy with a steadily rising incidence. Standard clinical practice is radical orchidectomy of suspicious lumps followed by histopathological diagnosis and tumor subtyping. This practice can lead to complications and quality of life issues for the patients. Liquid biopsies, especially cell-free DNA (cfDNA), promised to be true surrogates for tissue biopsies, which are considered dangerous to perform in cases of testicular tumors. In this study, we have performed a systematic review on the potential of cfDNA in TGCT patient management, its potential challenges in translation to clinical application and possible approaches in further research.

Materials & Methods:

The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines on EuropePMC and PUBMED electronic databases, with the last update being on October 21, 2021. Due to the high heterogeneity in identified research articles, we have performed an overview of their efficacy.

Results:

Eight original articles have been identified on cfDNA in TGCT patients published from 2004 to 2021, of which six had more than one TGCT patient enrolled and were included in the final analysis. Three studies investigated cfDNA methylation, one has investigated mutations in cfDNA, two have investigated cfDNA amount, and one has investigated cfDNA integrity in TGCT. The sensitivity of cfDNA for TGCT was found to be higher than in serum tumor markers and lower than miR-371a-3p, with comparable specificity. cfDNA methylation analysis has managed to accurately detect teratoma in TGCT patients.

Conclusion:

Potential challenges in cfDNA application to TGCT patient management were identified. The challenges relating to the biology of TGCT with its low mutational burden and low cfDNA amounts in blood plasma make next-generation sequencing (NGS) methods especially challenging. We have also proposed possible approaches to help find clinical application, including a focus on cfDNA methylation analysis, and potentially solving the challenge of teratoma detection.

Serum Levels of MicroRNA-371a-3p (M371) Can Predict Absence or Presence of Vital Disease in Residual Masses After Chemotherapy of Metastatic Seminoma

Background

Radiological evaluation of postchemotherapy residual masses of metastatic seminoma is characterized by poor diagnostic accuracy. Serum levels of microRNA-371a-3p (M371) involve high specificity and sensitivity for the primary diagnosis of seminoma. We evaluated if M371 levels can indicate the presence of vital disease in postchemotherapy residual masses in patients with metastatic seminoma.

Methods

Twenty-three seminoma patients (median age 52 years) with residual masses had posttreatment measurements of serum M371 levels (group A), fourteen of whom had measurements also beforehand. The posttreatment results were compared with the clinical outcome during follow-up. Eleven patients with complete remission after treatment of metastatic seminoma (group B) and 33 men with non-malignant testicular diseases (group C) served as controls. M371 serum levels were measured by quantitative real-time PCR using miR-30b-5p as endogenous control. An evaluation was performed with descriptive statistical methods.

Results

Twenty-two patients of Group A had uneventful follow-up so far, twenty-one of whom had M371 level &lt;5, and one other had a mildly elevated level below relative quantity (RQ) = 10. One patient with a level of RQ = 26.2 rapidly progressed. The median posttreatment M371 level of the non-progressing patients of group A is not significantly different from the median level of the control group with complete remission (B). Before treatment, the median M371 levels in groups A and B were 507.6 and 143.9, respectively. In both groups, significant drops in M371 levels resulted from treatment.

Conclusion

Normal M371 serum levels at the time of completion of treatment of metastatic seminoma indicate the absence of vital seminoma in residual masses, while elevated levels &gt;RQ = 10 predict the presence of disease. The optimal timing of M371 measurement after chemotherapy and the appropriate cutoff level still need to be determined. Based on the present results, measuring serum M371 levels involves the potential of a novel tool for assessing postchemotherapy residual masses of metastatic seminoma.

MicroRNAs in Differentiation of Embryoid Bodies and the Teratoma Subtype of Testicular Cancer

BACKGROUND

Testicular germ cell tumours (TGCTs) are the most frequent tumour type among young, adult men. TGCTs can be efficiently treated, but metastases of the teratoma subtype, for which there are no circulating biomarkers, represent a challenge.

MATERIALS AND METHODS

Global microRNA expression in teratoma tissue and embryoid bodies was assessed using next-generation sequencing. Levels of microRNAs identified as potential biomarkers were obtained from serum of patients with teratoma and matched healthy men.

RESULTS

We identified miR-222-5p, miR-200a-5p, miR-196b-3p and miR-454-5p as biomarker candidates from the tumour tissue and embryoid body screening but the expression of these microRNAs was very low in serum and not statistically different between patients and controls. miR-375-3p was highly expressed, being highest in patients with teratoma (p=0.012) but the levels of expression in serum from these patients and healthy controls overlapped. miR-371a-3p was not expressed in serum from patients with pure teratoma, only in patients with mixed tumours.

CONCLUSION

The microRNA profiles of the teratoma subtype of TGCT and embryoid bodies were obtained and assessed for candidate circulating biomarkers, but none with high sensitivity and specificity for teratoma were identified in our study. We conclude that neither the proposed teratoma marker miR-375-3p nor miR-371a-3p are suitable as circulating teratoma markers.

Emerging Role of Biomarkers in Testicular Germ Cell Tumors

PURPOSE OF REVIEW

This review will focus on biomarkers in testicular germ cell tumors (TGCT), focusing on microRNAs with high potential clinical application to drive management of TGCT. We explore the mechanism of action of microRNAs, literature to date, and how microRNAs may be incorporated into clinical practice in the near future.

RECENT FINDINGS

MicroRNAs are small non-coding RNAs found in blood which play an important role in post-transcriptional gene regulation and have been explored in TGCT for the past 15 years. More recently, results show they are promising biomarkers for diagnosis with impressive sensitivity and specificity, while also being cost-effective. MicroRNAs will likely play a critical role in areas of unmet need in GCT in the next decade, as they have many of the characteristics of an ideal biomarker. Ongoing prospective clinical trials evaluating microRNA-371 will be eagerly awaited and will help inform decision-making in real-world application.

Diagnostic, Prognostic and Predictive Markers in Pediatric Germ Cell Tumors—Past, Present and Future

Germ cell tumors (GCTs) are a heterogenous group of neoplasms in children and young adults, in which serum tumor markers have been demonstrated to be highly sensitive diagnostic and monitoring tools. The known "old" serum biomarkers, alpha-fetoprotein (AFP), human choriogonadotropin (β-hCG) and lactate dehydrogenase (LDH), have some limitations in sensitivity and specificity. MIRNAs from the miR-371~373 (chromosomal locus 19q13.41) and miR-302/367 (4q25) clusters are universally over-expressed in malignant GCT tissue samples. The levels of miRNAs from these clusters are elevated in the serum. They seem to be highly sensitive and specific in malignant GCTs diagnosis and disease assessment during treatment and follow-up. The aim of our review was to present the role of serum tumor markers in the clinical staging, treatment monitoring and follow-up of pediatric patients with GCTs and show new possibilities. The serum levels of miRNAs seem to be a new, promising essential tool in the clinical management of GCTs.

Editorial by Bendu K. Konneh, John T. Lafin and Aditya Bagrodia on pp. 341-342 of this issue: MicroRNA-371a-3p as a blood-based biomarker in testis cancer

MicroRNAs (miRNAs) are small noncoding RNAs involved in the regulation of mRNA transcription and translation, and possess all desirable features of an ideal tumor marker. Of almost 31 different miRNA clusters identified in germ cell tumors (GCTs), miR-371a-3p has shown exceptionally high sensitivity and specificity for both seminomatous and nonseminomatous GCTs. It is easily obtainable and correlates well with tumor burden. Recent multi-institutional prospective studies have shown promising test characteristics for miR-371a-3p as a diagnostic blood-based biomarker for GCT prior to orchiectomy including 80%-100% sensitivity and 90%-100% specificity. This accuracy may address other unmet needs in the management of patients with GCT. Early studies have suggested the utility of miR-371a-3p in detecting occult nodal metastasis in high-risk clinical stage I and early stage II disease. Ongoing clinical trials including SWOG 1823 and AGCT1531 are specifically designed to confirm the utility of miR-371a-3p in clinical stage I GCT. Despite its strong association with viable GCT after treatment with chemotherapy, miR-371a-3p does not seem to accurately predict the presence of teratoma in residual lesions. Also, standardization of extraction and interpretation methods is a necessary step to assure uniform results across different institutions.

Comparative Analyses of Liquid-Biopsy MicroRNA371a-3p Isolation Protocols for Serum and Plasma

Simple Summary

The active disease status of patients with a malignant germ cell tumor can be evaluated using detection of specific body-circulating microRNAs. However, various methods are reported to isolate and detect microRNAs from blood, possibly influencing the score as positive or negative. Here, we investigated two frequently used techniques for microRNA isolation from blood, either serum or plasma, to evaluate possible differences. These data are required to compare published studies and to select the best methods in the future. No effect of either starting with plasma or serum was found, indicating that both blood products can be used. The bead-based method was more stable and applicable on small blood volumes, whereas the total RNA method exhibited a higher sensitivity due to a larger starting volume. These results are important to develop the optimal method for the detection of microRNAs in blood to monitor malignant germ cell tumor patients in clinic practice.

Abstract

MicroRNAs (miRNAs) are short, non-coding RNAs involved in translation regulation. Dysregulation has been identified in cancer cells. miRNAs can be secreted and detectable in body fluids; therefore, they are potential liquid-biopsy biomarkers. The miR-371a-3 cluster members are an example, monitoring the presence of malignant germ cell tumors based on patient serum/plasma analyses. However, a large variety of isolation techniques on sample types (serum vs. plasma) are reported, hampering interstudy comparisons. Therefore, we analyzed the impact of using the miRNeasy Serum/Plasma Kit (cell-free total RNA purification) Qiagen extraction kit and the TaqMan anti-miRNA bead-capture procedure of ThermoFisher for miRNA isolation. Ten normal male matched serum and plasma samples and seventeen testicular germ cell tumor patient serum samples were investigated. The Qiagen kit requires a higher input volume (200 µL vs. 50 µL), resulting in higher sensitivity. Serum and plasma comparison demonstrated high similarity in miRNA levels. Titration experiments showed that the bead-capture procedure is superior in cases of lower starting volumes (<100 µL). This study highlights the strengths and limitations of two different isolation protocols, relevant for in vivo analysis with small starting volumes. In summary, miRNA detection levels results varied little between plasma and serum, whereas for low volumes the bead capture isolation method is preferable.

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.