Prognostic value of microphthalmia-associated transcription factor and tyrosinase as markers for circulating tumor cells detection in patients with melanoma

Liquid biopsy for diagnostic and prognostic evaluation of melanoma

Melanoma is the most aggressive form of skin cancer, and the majority of cases are associated with chronic or intermittent sun exposure. The incidence of melanoma has grown exponentially over the last 50 years, especially in populations of fairer skin, at lower altitudes and in geriatric populations. The gold standard for diagnosis of melanoma is performing an excisional biopsy with full resection or an incisional tissue biopsy. However, due to their invasiveness, conventional biopsy techniques are not suitable for continuous disease monitoring. Utilization of liquid biopsy techniques represent substantial promise in early detection of melanoma. Through this procedure, tumor-specific components shed into circulation can be analyzed for not only diagnosis but also treatment selection and risk assessment. Additionally, liquid biopsy is significantly less invasive than tissue biopsy and offers a novel way to monitor the treatment response and disease relapse, predicting metastasis.

Promising Blood-Based Biomarkers for Melanoma: Recent Progress of Liquid Biopsy and Its Future Perspectives

OPINION STATEMENT

Because the recent success of novel therapeutic approaches has dramatically changed the clinical management of melanoma, less invasive and repeatable monitoring tools that can predict the disease status, drug resistance, and the development of side effects are increasingly needed. As liquid biopsy has enabled us to diagnose and monitor disease status less invasively, substantial attention has been directed toward this technique, which is gaining importance as a diagnostic and/or prognostic tool. It is evident that microRNA, cell-free DNA, and circulating tumor cells obtained via liquid biopsy are promising diagnostic and prognostic tools for melanoma, and they also have utility for monitoring the disease status and predicting drug effects. Although current challenges exist for each biomarker, such as poor sensitivity and/or specificity and technical problems, recent technical advances have increasingly improved these aspects. For example, next-generation sequencing technology for detecting microRNAs or cell-free DNA enabled high-throughput analysis and provided significantly higher sensitivity. In particular, cancer personalized profiling by deep sequencing for quantifying cell-free DNA is a promising method for high-throughput analysis that provides real-time comprehensive data for patients at various disease stages. For wide clinical implementation, it is necessary to increase the sensitivity for the markers and standardize the assay procedures to make them reproducible, valid, and inexpensive; however, the broad clinical application of liquid biopsy could occur quickly. This review focuses on the significance of liquid biopsy, particularly related to the use of blood samples from patients with melanoma, and discusses its future perspectives.

Recent Developments of Circulating Tumor Cell Analysis for Monitoring Cutaneous Melanoma Patients

Simple Summary

Circulating tumor cells (CTCs) originating from cutaneous melanoma patients have been studied for several decades as surrogates for real-time clinical status and disease outcomes. Here, we will review clinical studies from the last 15 years that assessed CTCs and disease outcomes for melanoma patients. Assessment of multiple molecular melanoma-associated antigen (MAA) markers by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was the most common assay allowing for the improvement of assay sensitivity, to address tumor heterogeneity, and to predict patient outcomes. Multicenter studies demonstrate the utility of CTC assays reducing the bias observed in single-center trials. Recent development of CTC enrichment platforms has provided reproducible methods. CTC assessment enables both multiple mRNAs and DNAs genomic profiling. CTC provides specific important translational information on tumor progression, prediction of treatment response, and survival outcomes for cutaneous melanoma patients.

Abstract

Circulating tumor cells (CTCs) have been studied using multiple technical approaches for interrogating various cancers, as they allow for the real-time assessment of tumor progression, disease recurrence, treatment response, and tumor molecular profiling without the need for a tumor tissue biopsy. Here, we will review studies from the last 15 years on the assessment of CTCs in cutaneous melanoma patients in relation to different clinical outcomes. The focus will be on CTC detection in blood samples obtained from cutaneous melanoma patients of different clinical stages and treatments utilizing multiple platforms. Assessment of multiple molecular melanoma-associated antigen (MAA) markers by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was the most common assay allowing for the improvement of assay sensitivity, tumor heterogeneity, and to predict patient outcomes. Multicenter studies demonstrate the utility of CTC assays reducing the bias observed in single- center trials. The recent development of CTC enrichment platforms has provided reproducible methods. CTC assessment enables both multiple mRNAs and DNAs genomic aberration profiling. CTC provides specific important translational information on tumor progression, prediction of treatment response, and survival outcomes for cutaneous melanoma patients. The molecular studies on melanoma CTCs have provided and may set standards for other solid tumor CTC analyses.

Role of Biomarkers in the Integrated Management of Melanoma

Melanoma, which is an aggressive skin cancer, is currently the fifth and seventh most common cancer in men and women, respectively. The American Cancer Society reported that approximately 106,110 new cases of melanoma were diagnosed in the United States in 2021, with 7,180 people dying from the disease. This information could facilitate the early detection of possible metastatic lesions and the development of novel therapeutic techniques for melanoma. Additionally, early detection of malignant melanoma remains an objective of melanoma research. Recently, melanoma treatment has substantially improved, given the availability of targeted treatments and immunotherapy. These developments have highlighted the significance of identifying biomarkers for prognosis and predicting therapy response. Biomarkers included tissue protein expression, circulating DNA detection, and genetic alterations in cancer cells. Improved diagnostic and prognostic biomarkers are becoming increasingly relevant in melanoma treatment, with the development of newer and more targeted treatments. Here, the author discusses the aspects of biomarkers in the real-time management of patients with melanoma.

A feasibility study of circulating melanoma cells in the perioperative context of hyperthermic isolated limb perfusion (HILP) in 20 patients

INTRODUCTION

Hyperthermic Ιsolated Limb Perfusion using melphalan and TNFα (TM-HILP) is a regional chemotherapy method for advanced melanoma.

PURPOSE

To explore the feasibility of the study of Circulating Melanoma Cells (CMCs) in the context of acute physiological changes induced by TM-HILP and their association with oncological outcomes.

METHODS

The study included 20 patients undergoing TM-HILP for unresectable in-transit melanoma of the limbs, stage III(B/C/D). CMCs in the peripheral blood were analyzed at 5-time points from the preoperative day until day 7 from surgery using the following biomarkers: MITF, Tyrosinase mRNA, Melan-A and S100b, through quantitative RT-PCR.

RESULTS

No CMCs according to Tyrosinase and Melan-A biomarkers were found in any sample. Friedman test showed significant alterations perioperatively for MITF (p < .001) and S100b (p = .001). Pairwise tests showed a significant increase of MITF levels on postoperative day 7 compared with postoperative day 1, intraoperative and preoperative levels (p < .05). Pairwise tests for S100b showed a significant difference between intraoperative sample and postoperative day 7 (p < .0001). Patients who experienced a complete response to TM-HILP (n = 12) had higher mean levels of MITF and the difference was significant at the time point immediately after the operation (0.29 ± 0.27 vs. 0.06 ± 0.06, p = .014) and on postoperative day 1 (1.48 ± 2.24 vs. 0.41 ± 0.65, p = .046). There was no association of MITF or S100b levels with 4-year disease specific survival.

CONCLUSION

TM-HILP is associated with increased levels of CMCs, but there was no association of this increase with survival. Patients with complete response to HILP demonstrate higher values of MITF shortly after the operation.

Clinical Relevance of Liquid Biopsy in Melanoma and Merkel Cell Carcinoma

Melanoma and Merkel cell carcinoma are two aggressive skin malignancies with high disease-related mortality and increasing incidence rates. Currently, invasive tumor tissue biopsy is the gold standard for their diagnosis, and no reliable easily accessible biomarker is available to monitor patients with melanoma or Merkel cell carcinoma during the disease course. In these last years, liquid biopsy has emerged as a candidate approach to overcome this limit and to identify biomarkers for early cancer diagnosis, prognosis, therapeutic response prediction, and patient follow-up. Liquid biopsy is a blood-based non-invasive procedure that allows the sequential analysis of circulating tumor cells, circulating cell-free and tumor DNA, and extracellular vesicles. These innovative biosources show similar features as the primary tumor from where they originated and represent an alternative to invasive solid tumor biopsy. In this review, the biology and technical challenges linked to the detection and analysis of the different circulating candidate biomarkers for melanoma and Merkel cell carcinoma are discussed as well as their clinical relevance.

Circulating Tumor Cells in Stage IV Melanoma Patients

BACKGROUND

Management of stage IV melanoma patients remains a challenge. In spite of promising new therapies, many patients develop resistance and progression. The aim of this pilot study was to determine if circulating tumor cells (CTCs) are associated with shortened (180-day) progression-free survival (PFS) after a baseline CTC assessment in stage IV melanoma patients.

STUDY DESIGN

A baseline CTC assessment was performed in 93 stage IV melanoma patients using a commercially available immunomagnetic system. The presence of 1 or more CTC was considered a positive result. A Cox multivariable regression model was used to evaluate the association between presence of CTCs at baseline and PFS, after adjusting for covariables. Kaplan-Meier curves and a log-rank test were used to summarize and compare unadjusted PFS for patients stratified by CTC positivity.

RESULTS

Median follow-up was 17 months; mean age was 55 years. Thirteen of 93 (14%) patients had no evidence of disease (NED) at baseline CTC assessment. One or more CTC was detected in 39 of 93 (42%) of patients at baseline; CTCs were not associated with primary melanoma features or NED status. Twenty-eight of 93 (30%) patients progressed within 180 days of baseline draw, with 20 of 39 (51%) of the CTC-positive patients relapsing compared with 8 of 54 (15%) of the CTC-negative patients. In adjusted Cox models, a significant association was found suggesting worse PFS within 180 days for CTC-positive patients at baseline (vs CTC-negative) (hazard ratio 4.69, 95% CI 1.59 to 13.77, p = 0.005).

CONCLUSIONS

One or more CTCs at baseline were associated with progression within 180 days in stage IV melanoma patients. This information warrants further study of CTCs as a means of identifying patients at high-risk for disease progression.

Serum CEACAM1 Elevation Correlates with Melanoma Progression and Failure to Respond to Adoptive Cell Transfer Immunotherapy

Malignant melanoma is a devastating disease whose incidences are continuously rising. The recently approved antimelanoma therapies carry new hope for metastatic patients for the first time in decades. However, the clinical management of melanoma is severely hampered by the absence of effective screening tools. The expression of the CEACAM1 adhesion molecule on melanoma cells is a strong predictor of poor prognosis. Interestingly, a melanoma-secreted form of CEACAM1 (sCEACAM1) has recently emerged as a potential tumor biomarker. Here we add novel evidences supporting the prognostic role of serum CEACAM1 by using a mice xenograft model of human melanoma and showing a correlation between serum CEACAM1 and tumor burden. Moreover, we demonstrate that serum CEACAM1 is elevated over time in progressive melanoma patients who fail to respond to immunotherapy as opposed to responders and stable disease patients, thus proving a correlation between sCEACAM1, response to treatment, and clinical deterioration.

Detection of circulating melanoma cells in the blood of melanoma patients: a preliminary study

Significant prognostic heterogeneity exists within the substages of melanoma; therefore, novel prognostic biomarkers are needed to provide information on the risk of recurrence. Limited available data suggest prognostic significance for circulating melanoma cells (CMCs); there is a need for a sensitive, reproducible, and standardized identification technique. Using a semiautomated technology, we sought to determine whether CMCs could be identified reliably in stage I-IV melanoma patients and whether the presence of CMC correlated with known prognostic factors. CMCs were detected in the peripheral blood (7.5 ml) of patients with stage I-IV melanoma (n=89) using the CellSearch system. CD146 cells were immunomagnetically enriched; nucleated HMW-MAA/CD45/CD34 cells were considered CMCs. One or more CMCs was detected in 45% of all patients, varying with stage of disease (stages I/II, III, and IV: 35, 44, and 86%, respectively; P=0.03, for stage I/II vs. stage IV); 55% had one CMC, 32% had two CMCs, and 13% had three or more CMCs identified. The presence of CMCs in the blood was associated with histologic subtype, particularly in patients with stage I/II disease (superficial spreading 18% vs. acral lentiginous 75%). Using a semiautomated technique, CMCs can be identified in a significant number of melanoma patients. These data support further study with longer follow-up and longitudinal/serial time points to better determine the identification rates and prognostic significance of CMCs in stage I-IV melanoma patients.

Circulating biomarkers in malignant melanoma

Melanoma is an aggressive tumor with increasing incidence worldwide. Biomarkers are valuable tools to minimize the cost and improve efficacy of treatment of this deadly disease. Serological markers have not widely been introduced in routine clinical practice due to their insufficient diagnostic sensitivity and specificity. It is likely that the lack of objective responses with traditional treatment hinder biomarker research and development in melanoma. Recently, new drugs and therapies have, however, emerged in advanced melanoma with noticeable objective response ratio and survival. In this new scenario, serological tumor markers should be revisited. In addition, other potential circulating biomarkers such as cell-free DNA, exosomes, microRNA, and circulating tumor cells have also been identified. In this review, we summarize classical and emerging tumor markers and discuss their possible roles in emerging therapeutics.

Evaluating biomarkers in melanoma

The incidence of cutaneous melanoma has more than doubled over the last decades making it one of the fastest rising cancers worldwide. Improved awareness and early detection of malignant moles now permit earlier diagnosis aiming to decrease the likelihood of recurrence. However, it is difficult to identify those patients initially diagnosed with localized melanoma who subsequently develop metastatic disease. For this group, prognosis remains poor and clinical outcomes are variable and challenging to predict. Considerable efforts have focused on the search for novel prognostic tools, with numerous markers evaluated in the circulation and in tumor lesions. The most reliable predictors of patient outcome are the clinical and histological features of the primary tumor such as Breslow thickness, ulceration status, and mitotic rate. Elevated serum levels of the enzyme lactate dehydrogenase, likely to indicate active metastatic disease, are also routinely used to monitor patients. The emergence of novel immune and checkpoint antibody treatments for melanoma and increasing appreciation of key roles of the immune system in promoting or halting cancer progression have focused attention to immunological biomarkers. Validation of the most promising of these may have clinical applications in assisting prognosis, assessing endpoints in therapy, and monitoring responses during treatment.

Detection methods of circulating tumor cells in cutaneous melanoma: a systematic review

The vast majority of melanoma-related deaths are due to disseminated malignancy. Many treated patients who are clinically disease-free will go on to relapse. Therefore, new prognostic tools must be developed to better assess metastatic potential and assist in patient management. Circulating tumor cells are a widely studied metastatic biomarker with promising prognostic utility, as the shedding of cells from the primary tumor into peripheral blood is a necessary step in disease dissemination. An assortment of technologies and techniques has been developed to isolate and detect circulating melanoma cells (CMCs), but a standardized method is yet to be established. It is the aim of this study to systematically review the diverse enrichment and detection methods of circulating tumor cells in cutaneous melanoma. A literature search yielded 351 articles, of which 74 were deemed eligible according to inclusion criteria, the primary requirement being the reporting of patient CMC positivity status stratified by the stage of melanoma. Pertinent studies were used to evaluate the advantages and disadvantages of each method. Additionally, we calculated the sensitivity and specificity of seven common melanoma-associated markers based on the available literature.

Current status of diagnostic and prognostic markers in melanoma

Melanoma is the most life-threatening common form of skin cancer. While most cutaneous melanomas are cured by surgical resection, a minority will relapse locally, regionally, or distantly. Biomarkers have represented a focal point for research aimed at improving diagnostic accuracy as well as providing prognostic information that may help to guide therapeutic decisions. While systemic melanoma therapies were of extremely limited utility for patients with advanced disease in the past, two drugs have been approved the FDA within the past several years, and it is possible that they may provide even greater impact if employed earlier in the disease process. To optimally employ these therapies, prognostic biomarkers may offer significant value. This article reviews methodologies for both discovery and routine testing of melanoma biomarkers. It also focuses on specific commonly used markers, as well as approaches to studying their applications to specific clinical settings. As the armamentarium of melanoma drugs grows, it is hoped that specific biomarkers will aid in guiding the use of these agents for patients in the clinic.

MERTK controls melanoma cell migration and survival and differentially regulates cell behavior relative to AXL

The receptor tyrosine kinase AXL regulates melanoma cell proliferation and migration. We now demonstrate that AXL and the related kinase MERTK are alternately expressed in melanoma and are associated with different transcriptional signatures. MERTK-positive melanoma cells are more proliferative and less migratory than AXL-positive melanoma cells and overexpression of AXL increases cell motility relative to MERTK. MERTK is expressed in up to 50% of melanoma cells and shRNA-mediated knockdown of MERTK reduces colony formation and cell migration in a CDC42-dependent fashion. Targeting MERTK also decreases cell survival and proliferation in an AKT-dependent manner. Finally, we identify a novel mutation in the kinase domain of MERTK, MERTK(P) (802S) , that increases the motility of melanoma cells relative to wild-type MERTK. Together, these data demonstrate that MERTK is a possible therapeutic target in melanoma, that AXL and MERTK are associated with differential cell behaviors, and that mutations in MERTK may contribute to melanoma pathogenesis.

Circulating tumor cells in melanoma patients

Circulating tumor cells (CTCs) are of recognized importance for diagnosis and prognosis of cancer patients. With melanoma, most studies do not show any clear relationship between CTC levels and stage of disease. Here, CTCs were enriched (∼400X) from blood of melanoma patients using a simple centrifugation device (OncoQuick), and 4 melanocyte target RNAs (TYR, MLANA, MITF, and MIF) were quantified using QPCR. Approximately one-third of melanoma patients had elevated MIF and MLANA transcripts (p<0.0001 and p<0.001, respectively) compared with healthy controls. In contrast, healthy controls had uniformly higher levels of TYR and MITF than melanoma patients (p<0.0001). There was a marked shift of leukocytes into the CTC-enriched fractions (a 430% increase in RNA recovery, p<0.001), and no relationship between CTC levels and stage of disease was found. CTCs were captured on microfabricated filters and cultured. Captured melanoma CTCs were large cells, and consisted of 2 subpopulations, based on immunoreactivity. One subpopulation (∼50%) stained for both pan-cytokeratin (KRT) markers and the common leukocyte marker CD-45, whereas the second subpopulation stained for only KRT. Since similar cells are described in many cancers, we also examined blood from colorectal and pancreatic cancer patients. We observed analogous results, with most captured CTCs staining for both CD-45/KRT markers (and for the monocyte differentiation marker CD-14). Our results suggest that immature melanocyte-related cells (expressing TYR and MITF RNA) may circulate in healthy controls, although they are not readily detectable without considerable enrichment. Further, as early-stage melanomas develop, immature melanocyte migration into the blood is somehow curtailed, whereas a significant proportion of patients develop elevated CTC levels (based on MIF and MLANA RNAs). The nature of the captured CTCs is consistent with literature describing leukocyte/macrophage-tumor cell fusion hybrids, and their role in metastatic progression.

Isolation of tumorigenic circulating melanoma cells

Circulating tumor cells (CTC) have been identified in several human malignancies, including malignant melanoma. However, whether melanoma CTC are tumorigenic and cause metastatic progression is currently unknown. Here, we isolate for the first time viable tumorigenic melanoma CTC and demonstrate that this cell population is capable of metastasis formation in human-to-mouse xenotransplantation experiments. The presence of CTC among peripheral blood mononuclear cells (PBMC) of murine recipients of subcutaneous (s.c.) human melanoma xenografts could be detected based on mRNA expression for human GAPDH and/or ATP-binding cassette subfamily B member 5 (ABCB5), a marker of malignant melanoma-initiating cells previously shown to be associated with metastatic disease progression in human patients. ABCB5 expression could also be detected in PBMC preparations from human stage IV melanoma patients but not healthy controls. The detection of melanoma CTC in human-to-mouse s.c. tumor xenotransplantation models correlated significantly with pulmonary metastasis formation. Moreover, prospectively isolated CTC from murine recipients of s.c. melanoma xenografts were capable of primary tumor initiation and caused metastasis formation upon xenotransplantation to secondary murine NOD-scid IL2Rγ(null) recipients. Our results provide initial evidence that melanoma CTC are tumorigenic and demonstrate that CTC are capable of causing metastatic tumor progression. These findings suggest a need for CTC eradication to inhibit metastatic progression and provide a rationale for assessment of therapeutic responses of this tumorigenic cell population to promising emerging melanoma treatment modalities.