Circulating MicroRNAs for Detection of Germ Cell Tumours: A Narrative Review

A comprehensive overview of liquid biopsy applications in pediatric solid tumors

Liquid biopsies are emerging as an alternative source for pediatric cancer biomarkers with potential applications during all stages of patient care, from diagnosis to long-term follow-up. While developments within this field are reported, these mainly focus on dedicated items such as a specific liquid biopsy matrix, analyte, and/or single tumor type. To the best of our knowledge, a comprehensive overview is lacking. Here, we review the current state of liquid biopsy research for the most common non-central nervous system pediatric solid tumors. These include neuroblastoma, renal tumors, germ cell tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma and other soft tissue sarcomas, and liver tumors. Within this selection, we discuss the most important or recent studies involving liquid biopsy-based biomarkers, anticipated clinical applications, and the current challenges for success. Furthermore, we provide an overview of liquid biopsy-based biomarker publication output for each tumor type based on a comprehensive literature search between 1989 and 2023. Per study identified, we list the relevant liquid biopsy-based biomarkers, matrices (e.g., peripheral blood, bone marrow, or cerebrospinal fluid), analytes (e.g., circulating cell-free and tumor DNA, microRNAs, and circulating tumor cells), methods (e.g., digital droplet PCR and next-generation sequencing), the involved pediatric patient cohort, and proposed applications. As such, we identified 344 unique publications. Taken together, while the liquid biopsy field in pediatric oncology is still behind adult oncology, potentially relevant publications have increased over the last decade. Importantly, steps towards clinical implementation are rapidly gaining ground, notably through validation of liquid biopsy-based biomarkers in pediatric clinical trials.

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.

Advancing GCT Management: A Review of miR-371a-3p and Other miRNAs in Comparison to Traditional Serum Tumor Markers

MicroRNAs, short non-protein coding RNAs, are overexpressed in GCTs. Circulating levels of germ cell tumor (GCT)-associated miRNAs, such as miR-371a-3p, can be utilized as efficient and cost-effective alternatives in diagnosing and managing patients presenting with GCTs. This quality of miRNAs has demonstrated favorable performance characteristics as a reliable blood-based biomarker with high diagnostic accuracy compared to current serum tumor markers (STMs), including α-fetoprotein (AFP), beta human chorionic gonadotropin (β-hCG), and lactate dehydrogenase (LDH). The conventional STMs exhibit limited specificity and sensitivity. Potential clinical implications of miRNAs include impact on de-escalating or intensifying treatment, detecting recurrence at earlier stages, and lessening the necessity of cross-sectional imaging or invasive tissue biopsy for non-teratomatous GCTs. Here, we also highlight the outstanding issues that must be addressed prior to clinical implementation. Standards for measuring circulating miRNAs and determining ideal cutoff values are essential for integration into current clinical guidelines.

Retroperitoneal Lymph Node Dissection in Clinical Stage IIA/B Metastatic Seminoma: Results of the COlogne Trial of Retroperitoneal Lymphadenectomy In Metastatic Seminoma (COTRIMS)

BACKGROUND

Radiation therapy and systemic chemotherapy are recommended treatment options in marker-negative clinical stage (CS) IIA/B seminoma. Despite high cure rates of 82-94%, both therapeutic options are associated with significant long-term toxicities.

OBJECTIVE

To evaluate the feasibility, oncological efficacy, and treatment-associated morbidity of primary nerve-sparing retroperitoneal lymph node dissection (nsRPLND) in CS IIA/B seminoma.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, single-arm, clinical phase 2 trial including CS IIA/B seminoma patients was conducted.

INTERVENTION

Primary nerve-sparing retroperitoneal lymphadenectomy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Relapse-free and overall survival, surgery-associated complications according to the Clavien-Dindo classification, and Kaplan-Meier methods for survival calculation were assessed.

RESULTS AND LIMITATIONS

Thirty patients at a mean age of 39.1 (34-52) yr with marker-negative CS IIA and IIB seminomas were recruited. The median follow-up was 22 (8-30) mo. Nineteen (63%) and 11 (36%) patients were diagnosed with stages IIA and B, respectively, at the time of primary diagnosis. Fourteen (47%) and 16 (53%) patients were diagnosed with CS IIA and IIB, respectively, at the time of nsRPLND. Twenty-seven and three patients underwent open and robot-assisted nsRPLND, respectively. The median operating room time was 125 (115-145) min, median blood loss was <150 ml, and median time of hospitalization was 4.5 (3-9) d. Four (13%) patients experienced Clavien-Dindo grade 3a complications. Lymph node histology revealed seminoma in 25 (80%) patients; two and three patients demonstrated embryonal carcinoma and benign disease, respectively. Sixteen patients underwent a serum analysis of miR371 preoperatively, which predicted metastatic disease in 12/13 and benign histology in 3/3 patients. Three of 30 (10%) patients developed an outfield relapse 4, 6, and 9 mo postoperatively and were salvaged by systemic chemotherapy. Limitations are the low patient number and length of follow-up.

CONCLUSIONS

The nsRPLND approach results in a high cure rate at midterm follow-up and is associated with a low frequency of treatment-associated morbidities, making this approach a feasible alternative to radiation therapy or systemic chemotherapy.

PATIENT SUMMARY

The standard treatment of clinical stage IIA/B seminomas is radiation therapy or chemotherapy, which results in a significantly increased frequency of long-term toxicity and secondary neoplasms. In this trial, we demonstrate that nerve-sparing retroperitoneal lymph node dissection is a feasible therapeutic approach with low morbidity and high oncological efficacy.

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.

Risk Factors for Relapse in Nonseminomatous Testicular Cancer After Postchemotherapy Retroperitoneal Lymph Node Dissection With Viable Residual Cancer

PURPOSE

No consensus exists on the management of men with nonseminoma and viable nonteratomatous germ cell tumor in the postchemotherapy retroperitoneal lymph node dissection (pcRPLND) specimen after first-line chemotherapy. We analyzed surveillance versus different adjuvant chemotherapy regimens and the influence of time to pcRPLND on oncologic outcomes.

METHODS

Data on 117 men treated with cisplatin-based first-line chemotherapy between 1990 and 2018 were collected from 13 institutions. All patients had viable nonteratomatous germ cell tumor in the pcRPLND specimen. Surgery was performed after a median of 57 days, followed by either surveillance (n = 64) or adjuvant chemotherapy (n = 53). Primary end points were progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS).

RESULTS

After controlling for International Germ Cell Cancer Cooperative Group risk group and percent of viable malignant cells found at RPLND, no difference was observed between men managed with surveillance or adjuvant chemotherapy regarding PFS (hazard ratio [HR], 0.72 [95% CI, 0.32 to 1.6]; P = .4), CSS (HR, 0.69; 95% CI, 0.20 to 2.39; P = .6), and OS (HR, 0.78 [95% CI, 0.25 to 2.44]; P = .7). No statistically significant differences for PFS, CSS, or OS were observed on the basis of chemotherapy regimen or in men treated with pcRPLND ≤57 versus >57 days after first-line chemotherapy. Residual disease with <10% versus ≥10% viable cancer cells were associated with a longer PFS (HR, 3.22 [95% CI, 1.29 to 8]; P = .012). Relapse in the retroperitoneum was observed in 34 (29%) men.

CONCLUSION

Men with a complete resection at pcRPLND and <10% viable cells have favorable outcomes without further treatment. Complete retroperitoneal resection seems more important than early pcRPLND.

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.

Children's Oncology Group's 2023 blueprint for research: Germ cell tumors

Extracranial germ cell tumors (GCT) are a biologically diverse group of tumors occurring in children, adolescents, and young adults. The majority of patients have excellent outcomes, but treatment-related toxicities impact their quality of survivorship. A subset of patients succumbs to the disease. Current unmet needs include clarifying which patients can be safely observed after initial surgical resection, refinement of risk stratification to reduce chemotherapy burden in patients with standard-risk disease, and intensify therapy for patients with poor-risk disease. Furthermore, enhancing strategies for detection of minimal residual disease and early detection of relapse, particularly in serum tumor marker-negative histologies, is critical. Improving the understanding of the developmental and molecular origins of GCTs may facilitate discovery of novel targets. Future efforts should be directed toward assessing novel therapies in a biology-driven, biomarker-defined, histology-specific, risk-stratified patient population. Fragmentation of care between subspecialists restricts the unified study of these rare tumors. It is imperative that trials be conducted in collaboration with national and international cooperative groups, with harmonized data and biospecimen collection. Key priorities for the Children's Oncology Group (COG) GCT Committee include (a) better understanding the biology of GCTs, with a focus on molecular targets and mechanisms of treatment resistance; (b) strategic development of pediatric and young adult clinical trials; (c) understanding late effects of therapy and identifying individuals most at risk; and (d) prioritizing diversity, equity, and inclusion to reduce cancer health disparities and studying the impacts of social determinants of health on outcomes.

Testicular neoplasms: the interrelationships of serum levels of microRNA-371a-3p (M371) and classical tumor markers with histology, clinical staging, and age-a statistical analysis

PURPOSE

In testicular neoplasms, the interrelationship of elevations of the novel serum tumor marker microRNA-371a-3p (M371) and traditional markers with other clinical features is still incompletely understood. The present study evaluated marker expression rates in relation to various other clinical parameters.

METHODS

The following data were retrospectively registered from 641 consecutive patients with testicular neoplasms: histology, such as seminoma (n = 365), nonseminoma (n = 179), benign tumor (n = 79), other malignant tumor (n = 18); patients age (years); clinical stage (CS1, CS2a/b, CS2c, CS3); and preoperative elevation of beta HCG, AFP, LDH, M371 (yes/no). Descriptive statistical methods were employed with comparisons of various subgroups to disclose associations of marker expression rates with age, histology and CS, and of age with histology.

RESULTS

The histologic subgroups revealed significantly different expression rates of tumor markers. M371 performed best with expression rates of 82.69% and 93.58% in seminoma and in nonseminoma, respectively. In germ cell tumors, all markers had significantly higher expression rates in metastasized stages than in localized disease. All markers except LDH have significantly higher expression rates in younger than in older patients. Nonseminoma is most prevalent in the youngest age category, seminoma predominates in patients > 40 years, other malignancies were restricted to patients > 50 years.

CONCLUSION

The study documented significant associations of serum marker expression rates with histology, age and clinical staging, with highest rates in nonseminomas, young age and advanced clinical stages. M371 showed significantly higher expression rates than other markers suggesting its superior clinical usefulness.

Male Infertility and the Risk of Developing Testicular Cancer: A Critical Contemporary Literature Review

Background and Objectives: The relationship between male infertility (MI) and testicular cancer (TC) is bilateral. On one hand, it is well-established that patients diagnosed with TC have a high risk of pre- and post-treatment infertility. On the other hand, the risk of developing TC in male infertile patients is not clearly defined. The objective of this review is to analyze the histopathological, etiological, and epidemiological associations between MI and the risk of developing testicular cancer. This review aims to provide further insights and offer a guide for assessing the risk factors for TC in infertile men. Materials and Methods: A comprehensive literature search was conducted to identify relevant studies discussing the relationship between MI and the risk of developing TC. Results: The incidence rates of germ cell neoplasia in situ (GCNIS) appear to be high in infertile men, particularly in those with low sperm counts. Most epidemiological studies have found a statistically significant risk of developing TC among infertile men compared to the general or fertile male populations. The concept of Testicular Dysgenesis Syndrome provides an explanatory model for the common etiology of MI, TC, cryptorchidism, and hypospadias. Clinical findings such as a history of cryptorchidism could increase the risk of developing TC in infertile men. Scrotal ultrasound evaluation for testis lesions and microlithiasis is important in infertile men. Sperm analysis parameters can be useful in assessing the risk of TC among infertile men. In the future, sperm and serum microRNAs (miRNAs) may be utilized for the non-invasive early diagnosis of TC and GCNIS in infertile men. Conclusions: MI is indeed a risk factor for developing testicular cancer, as demonstrated by various studies. All infertile men should undergo a risk assessment using clinical examination, ultrasound, and semen parameters to evaluate their risk of TC.