Circulating tumour DNA (ctDNA) in metastatic melanoma, a systematic review and meta-analysis

Using liquid biopsies to guide treatment and monitor response in BRAF V600E positive adenocarcinoma of unknown primary

Liquid biopsies using circulating tumour DNA (ctDNA) have emerged as an alternative to conventional biopsies. They can be used to aid in diagnosing and selecting an agent for treatment and can possibly be used to monitor disease response to treatment. In this report, we present a patient who initially presented with lower abdominal pain. Imaging showed extensive retroperitoneal lymphadenopathy and lymph node biopsy demonstrated poorly differentiated carcinoma. Further workup did not reveal a primary lesion, but his genetic analysis revealed a BRAF V600E mutation and CD274 amplification which was used to guide treatment of the adenocarcinoma as a melanoma of unknown primary. He was initiated on ipilimumab and nivolumab and his ctDNA levels showed rapid improvement. After treatment was stopped due to adverse events, he was monitored via ctDNA, with an increase prompting repeat imaging that demonstrated enlargement of his lesions prompting a resumption of treatment.

Circulating immune cells exhibit distinct traits linked to metastatic burden in breast cancer

BACKGROUND

Circulating immune cells play a crucial role in the anti-tumour immune response, yet the systemic immune system in metastatic breast cancers is not fully characterised. Investigating the cellular and molecular changes in peripheral blood mononuclear cells (PBMCs) from breast cancer patients could elucidate the role of circulating immune cells in metastasis and aid in identifying biomarkers for disease burden and progression.

METHODS

In this study, we characterised the systemic immune landscape associated with varying levels of metastatic burden by analysing the single-cell transcriptomes of PBMCs from breast cancer patients and healthy controls. Our research focused on identifying changes in immune cell composition, transcriptional programs, and immune-cell communication networks linked to metastatic burden. Additionally, we compared these PBMC features onto a single-cell atlas of primary breast tumours to study corresponding traits in tumour-infiltrating immune cells.

RESULTS

In metastatic breast cancer, PBMCs exhibit a significant downregulation of the adaptive immune system and a decreased number and activity of unconventional T cells, such as γδ T cells. Additionally, metastatic burden is associated with impaired cell communication pathways involved in immunomodulatory functions. We also identified a gene signature derived from myeloid cells shared between tumour immune infiltrates and circulating immune cells in breast cancer patients.

CONCLUSIONS

Our study provides a comprehensive single-cell molecular profile of the peripheral immune system in breast cancer, offering a valuable resource for understanding metastatic disease in terms of tumour burden. By identifying immune traits linked to metastasis, we have unveiled potential new biomarkers of metastatic disease.

Predictive Factors for Sentinel Lymph Node Positivity in Melanoma Patients-The Role of Liquid Biopsy, MicroRNA and Gene Expression Profile Panels

The identification of predictive factors for sentinel lymph node (SLN) positivity in melanoma patients is crucial for accurate staging, prognosis, and personalized therapeutic decisions. This review synthesizes recent advancements in molecular and clinicopathological predictors, with a particular focus on liquid biopsy and gene expression profiling (GEP) tools. Emerging evidence highlights the significant role of miRNAs in melanoma progression, metastatic potential, and lymphatic spread. Clinicopathological factors such as Breslow thickness, ulceration, and mitotic rate remain critical, while GEP provides additional precision by uncovering tumor-specific molecular pathways. By integrating these tools, clinicians can improve risk stratification, reduce unnecessary procedures, and personalize management strategies.

Circulating Tumor DNA in High-Risk Stage II/III Cutaneous Melanoma: A Feasibility Study

BACKGROUND

Adjuvant therapies reduce recurrence in patients with clinical stage IIB/IIC/III melanoma; however, better risk stratification and patient selection are needed. Circulating tumor DNA (ctDNA) as a marker of micrometastatic residual disease is being explored for such purposes in other malignancies. We aimed to explore the feasibility of serial ctDNA monitoring in patients with stage II/III melanoma, as well as the association of ctDNA elevation with disease burden and outcomes.

METHODS

A single-institution prospective study was conducted on patients with clinical stage IIB/IIC/III melanoma. Primary tumor was sent to Natera for generation of a tumor-informed mPCR-NGS assay (Signatera™). Peripheral blood was collected for analysis at pre-specified timepoints. Patients were stratified by ctDNA elevations both pre- and postoperatively to compare tumor characteristics and recurrence-free survival (RFS).

RESULTS

Overall, 30 patients were enrolled. The median Breslow depth was 4.4 mm and 70% were ulcerated. Signatera™ assays were successfully created for all 30 patients. Median follow-up from the time of surgery was 16 months and 13 patients recurred with median RFS of 19 months. Eight of these 13 patients (62%) had detectable ctDNA levels predating their clinical or radiographic recurrence. Elevated ctDNA at the first post-operative timepoint was associated with worse RFS.

CONCLUSIONS

ctDNA monitoring is feasible for patients with high-risk cutaneous melanoma. Our findings suggest that detectable ctDNA post-operatively may be associated with worse outcomes. Elevations during surveillance may predict subsequent clinical recurrence; however, the role of ctDNA in adjuvant therapy decision-making and surveillance is not yet ready for broad application.

Prognostic Biomarkers in Evolving Melanoma Immunotherapy

Melanoma, a highly aggressive form of skin cancer, has seen significant advancements in treatment through the introduction of immunotherapy. However, the variability in patient responses underscores the need for reliable biomarkers to guide treatment decisions. This article reviews key biomarkers in melanoma immunotherapy, such as PD-L1 expression, tumor mutational burden (TMB), and gene expression profiles (GEPs). It also explores emerging biomarkers, including LAG-3 expression, immune cell phenotyping in tissue and blood, gut microbiota, and circulating tumor DNA (ctDNA). Notably, ctDNA may offer valuable insights into the efficacy of T cell-engaging bispecific molecules, such as tebentafusp. The review provides a comprehensive overview of the evolving landscape of melanoma biomarkers, their role in personalizing treatment, and future research directions, including neoadjuvant immune checkpoint inhibition.

European consensus-based interdisciplinary guideline for melanoma. Part 1: Diagnostics - Update 2024

This guideline was developed in close collaboration with multidisciplinary experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF) and the European Organization for Research and Treatment of Cancer (EORTC). Recommendations for the diagnosis and treatment of melanoma were developed on the basis of systematic literature research and consensus conferences. Cutaneous melanoma (CM) is the most dangerous form of skin tumor and accounts for 90 % of skin cancer mortality. The diagnosis of melanoma can be made clinically and must always be confirmed by dermoscopy. If melanoma is suspected, a histopathological examination is always required. Sequential digital dermoscopy and whole-body photography can be used in high-risk patients to improve the detection of early-stage melanoma. If available, confocal reflectance microscopy can also improve the clinical diagnosis in special cases. Melanoma is classified according to the 8th version of the American Joint Committee on Cancer classification. For thin melanomas up to a tumor thickness of 0.8 mm, no further diagnostic imaging is required. From stage IB, lymph node sonography is recommended, but no further imaging examinations. From stage IIB/C, whole-body examinations with computed tomography or positron emission tomography CT in combination with magnetic resonance imaging of the brain are recommended. From stage IIB/C and higher, a mutation test is recommended, especially for the BRAF V600 mutation. It is important to perform a structured follow-up to detect relapses and secondary primary melanomas as early as possible. A stage-based follow-up regimen is proposed, which in the experience of the guideline group covers the optimal requirements, although further studies may be considered. This guideline is valid until the end of 2026.

Circulating Tumor DNA: A Pan-Cancer Biomarker in Solid Tumors with Prognostic and Predictive Value

Circulating tumor DNA (ctDNA), often referred to as a liquid biopsy, represents a promising biomarker in the management of both localized and advanced solid tumors. It has garnered significant attention due to its potential to inform prognosis and guide therapeutic decisions. The clinical utility of ctDNA spans early cancer detection, minimal residual disease identification, recurrence surveillance, treatment monitoring, and precision oncology treatment decision-making in the advanced setting. Unlike conventional radiological assessments, the short half-life of ctDNA allows for more timely insights into disease dynamics. Several technological approaches are available to measure ctDNA, including next-generation sequencing and droplet digital polymerase chain reaction, although their clinical accuracy depends on multiple biological and technical factors. This review evaluates current evidence surrounding ctDNA's utility in early and advanced solid tumors.

Circulating tumor DNA-based assessment of molecular residual disease in non-metastatic melanoma

In patients with resected non-metastatic melanoma, the liquid biopsy for the assessment of molecular residual disease (MRD) by circulating tumour DNA (ctDNA) represents a promising tool to stratify the risk and to monitor tumour evolution. However, its validation requires the demonstration of analytical validity, clinical validity and utility. Indeed, the development of sensitive and specific assays can optimize prognostication and eventually help clinicians to modulate adjuvant treatments, in order to improve clinical outcomes. Data about ctDNA-guided prognosis stratification is emerging, but clinical trials assessing ctDNA-guided therapeutic decisions are still ongoing. This review aims to depict the role of ctDNA-based MRD assessment in patients with non-metastatic melanoma and to provide a roadmap to face challenges for its introduction into clinical practice.

Early On-Treatment Assessment of T Cells, Cytokines, and Tumor DNA with Adaptively Dosed Nivolumab + Ipilimumab: Final Results from the Phase 2 ADAPT-IT Study

PURPOSE

The Adaptively Dosed ImmunoTherapy Trial (ADAPT-IT;NCT03122522) investigated adaptive ipilimumab discontinuation in melanoma based on early radiographic assessment. Initial findings indicated similar effectiveness compared with conventional nivolumab-ipilimumab (nivo-ipi). Exploratory biomarker analyses and final clinical results are now reported.

PATIENTS AND METHODS

Patients with unresectable melanoma received two doses of nivo-ipi. Radiographic assessment at Week 6 informed continuation of ipilimumab before nivolumab maintenance. The primary endpoint was overall response rate at Week 12. Plasma was assayed for circulating tumor DNA and 10 cytokines using a multiplex immunoassay. Flow cytometry of peripheral blood mononuclear cells was performed with an 11-color panel.

RESULTS

Among the treated patients, expansion of proliferating T-cell populations was observed in responders and nonresponders. Baseline IL6 levels were low in patients achieving an objective radiographic response (median 1.30 vs. 2.86 pg/mL; P = 0.025). High baseline IL6 levels were associated with short progression-free survival [PFS; HR = 1.24, 95% confidence interval (CI), 1.01-1.52; P = 0.041]. At Week 6, patients with response had lower average tumor variant allele fractions than nonresponders (median 0.000 vs. 0.019; P = 0.014). Greater increases in average variant allele fractions from baseline to Week 6 correlated with short PFS (HR = 1.11, 95% CI, 1.01-1.21; P = 0.023). Week 12 overall response rate was 47% (95% CI, 35%-59%) with a median follow-up of 34 months among survivors. Median PFS was 21 months (95% CI, 10-not reached); 76% of responses (95% CI, 64%-91%) persisted at 36 months.

CONCLUSIONS

Adaptively dosed nivo-ipi responses are durable and resemble historical data for conventional nivo-ipi. Baseline IL6 and circulating tumor DNA changes during treatment warrant further study as biomarkers of nivo-ipi response.

Circulating tumor DNA (ctDNA) application in investigation of cancer: Bench to bedside

Now, genomics forms the core of the precision medicine concept. Comprehensive investigations of tumor genomes have made it possible to characterize tumors at the molecular level and, specifically, to identify the fundamental processes that cause condition. A variety of kinds of tumors have seen better outcomes for patients as a result of the development of novel medicines to tackle these genetic-driving processes. Since therapy may exert selective pressure on cancers, non-invasive methods such as liquid biopsies can provide the opportunity for rich reservoirs of crucial and real-time genetic data. Liquid biopsies depend on the identification of circulating cells from tumors, circulating tumor DNA (ctDNA), RNA, proteins, lipids, and metabolites found in patient biofluids, as well as cell-free DNA (cfDNA), which exists in those with cancer. Although it is theoretically possible to examine biological fluids other than plasma, such as pleural fluid, urine, saliva, stool, cerebrospinal fluid, and ascites, we will limit our discussion to blood and solely cfDNA here for the sake of conciseness. Yet, the pace of wider clinical acceptance has been gradual, partly due to the increased difficulty of choosing the best analysis for the given clinical issue, interpreting the findings, and delaying proof of value from clinical trials. Our goal in this review is to discuss the current clinical value of ctDNA in cancers and how clinical oncology systems might incorporate procedures for ctDNA testing.

Clinical and Imaging Follow-Up for High-Risk Cutaneous Melanoma: Current Evidence and Guidelines

The most recent (eighth) edition of the American Joint Committee on Cancer (AJCC) staging system divides invasive cutaneous melanoma into two broad groups: "low-risk" (stage IA-IIA) and "high-risk" (stage IIB-IV). While surveillance imaging for high-risk melanoma patients makes intuitive sense, supporting data are limited in that they are mostly respective and used varying methods, schedules, and endpoints. As a result, there is a lack of uniformity across different dermatologic and oncologic organizations regarding recommendations for follow-up, especially regarding imaging. That said, the bulk of retrospective and prospective data support imaging follow-up for high-risk patients. Currently, it seems that either positron emission tomography (PET) or whole-body computerized tomography (CT) are reasonable options for follow-up, with brain magnetic resonance imaging (MRI) preferred for the detection of brain metastases in patients who can undergo it. The current era of effective systemic therapies (ESTs), which can improve disease-free survival (DFS) and overall survival (OS) beyond lead-time bias, has emphasized the role of imaging in detecting various patterns of EST response and treatment relapse, as well as the importance of radiologic tumor burden.

US physician perspective on the use of biomarker and ctDNA testing in patients with melanoma

New treatments have increased survival of patients with melanoma, and methods to monitor patients throughout the disease process are needed. Circulating tumor DNA (ctDNA) is a predictive and prognostic biomarker that may allow routine, real-time monitoring of disease status. We surveyed 44 US physicians to understand their preferences and practice patterns for biomarker and ctDNA testing in their patients with melanoma. Tumor biomarker testing was often ordered in stage IIIA-IV patients. Barriers to biomarker testing include insufficient tissue (60%) and lack of insurance coverage (54%). ctDNA testing was ordered by 16-18% of physicians for stages II-IV. Reasons for not using ctDNA testing included lack of prospective data (41%), ctDNA testing used for research only (18%), and others. Physicians (≥74%) believed that ctDNA assays could help with monitoring and treatment selection throughout the disease process. Physicians consider ctDNA testing potentially valuable for clinical decision-making but cited concerns that should be addressed.

Corresponding ctDNA and tumor burden dynamics in metastatic melanoma patients on systemic treatment

Radiographic imaging is the current standard for monitoring progression of tumor-burden and therapeutic resistance in patients with metastatic melanoma. Plasma circulating tumor DNA (ctDNA) has shown promise as a survelience tool, but longitudinal data on the dynamics between plasma ctDNA concentrations and radiographic imaging is lacking. We evaluated the relationship between longitudinal radiographic measures of tumor burden and ctDNA concentrations in plasma on 30 patients with metastatic melanoma on systemic treatment. In 9 patients with no radiographic evidence of disease over a total of 15 time points, ctDNA concentrations were undetectable. In 21 patients with radiographic tumor burden, ctDNA was detected in 81 % of 58 time points. Plasma ctDNA concentrations demonstrated a modest positive correlation with total tumor burden (TTB) measurements (R2= 0.49, p < 0.001), with the greatest degree of correlation observed under conditions of progressive disease (PD) (R2 = 0.91, p = 0.032). Plasma ctDNA concentrations were significantly greater at times of RECIST v1.1 progression (PD; 22.1 % ± 5.7 %) when compared to samples collected during stable disease (SD; 4.99 % ± 3.0 %) (p = 0.012); this difference was independent of total tumor burden (p = 0.997). Changes in plasma ctDNA showed a strong correlation with changes in TTB (R2= 0.88, p<0.001). These data suggest that measurements of plasma ctDNA during therapy are a better surrogate for responding versus non-responding disease compared to absolute tumor burden.

Early Detection of Molecular Residual Disease and Risk Stratification for Children with Acute Myeloid Leukemia via Circulating Tumor DNA

PURPOSE

Patient-tailored minimal residual disease (MRD) monitoring based on circulating tumor DNA (ctDNA) sequencing of leukemia-specific mutations enables early detection of relapse for pre-emptive treatment, but its utilization in pediatric acute myelogenous leukemia (AML) is scarce. Thus, we aim to examine the role of ctDNA as a prognostic biomarker in monitoring response to the treatment of pediatric AML.

EXPERIMENTAL DESIGN

A prospective longitudinal study with 50 children with AML was launched, and sequential bone marrow (BM) and matched plasma samples were collected. The concordance of mutations by next-generation sequencing-based BM-DNA and ctDNA was evaluated. In addition, progression-free survival (PFS) and overall survival (OS) were estimated.

RESULTS

In 195 sample pairs from 50 patients, the concordance of leukemia-specific mutations between ctDNA and BM-DNA was 92.8%. Patients with undetectable ctDNA were linked to improved OS and PFS versus detectable ctDNA in the last sampling (both P < 0.001). Patients who cleared their ctDNA post three cycles of treatment had similar PFS compared with persistently negative ctDNA (P = 0.728). In addition, patients with >3 log reduction but without clearance in ctDNA were associated with an improved PFS as were patients with ctDNA clearance (P = 0.564).

CONCLUSIONS

Thus, ctDNA-based MRD monitoring appears to be a promising option to complement the overall assessment of pediatric patients with AML, wherein patients with continuous ctDNA negativity have the option for treatment de-escalation in subsequent therapy. Importantly, patients with >3 log reduction but without clearance in ctDNA may not require an aggressive treatment plan due to improved survival, but this needs further study to delineate.

The Use of Gene Expression Profiling and Biomarkers in Melanoma Diagnosis and Predicting Recurrence: Implications for Surveillance and Treatment

Cutaneous melanoma is becoming more prevalent in the United States and has the highest mortality among cutaneous malignancies. The majority of melanomas are diagnosed at an early stage and, as such, survival is generally favorable. However, there remains prognostic uncertainty among subsets of early- and intermediate-stage melanoma patients, some of whom go on to develop advanced disease while others remain disease-free. Melanoma gene expression profiling (GEP) has evolved with the notion to help bridge this gap and identify higher- or lower-risk patients to better tailor treatment and surveillance protocols. These tests seek to prognosticate melanomas independently of established AJCC 8 cancer staging and clinicopathologic features (sex, age, primary tumor location, thickness, ulceration, mitotic rate, lymphovascular invasion, microsatellites, and/or SLNB status). While there is a significant opportunity to improve the accuracy of melanoma prognostication and diagnosis, it is equally important to understand the current landscape of molecular profiling for melanoma treatment. Society guidelines currently do not recommend molecular testing outside of clinical trials for melanoma clinical decision making, citing insufficient high-quality evidence guiding indications for the testing and interpretation of results. The goal of this chapter is to review the available literature for GEP testing for melanoma diagnosis and prognostication and understand their place in current treatment paradigms.

IDH1 mutation is detectable in plasma cell-free DNA and is associated with survival outcome in glioma patients

BACKGROUND

Circulating cell-free DNA (cfDNA, liquid biopsy) is a powerful tool to detect molecular alterations. However, depending on tumor characteristics, biology and anatomic localization, cfDNA detection and analysis may be challenging. Gliomas are enclosed into an anatomic sanctuary, which obstacles the release of cfDNA into the peripheral blood. Therefore, the advantages of using liquid biopsy for brain tumors is still to be confirmed. The present study evaluates the ability of liquid biopsy to detect IDH1 mutations and its correlation with survival and clinical characteristics of glioma patients.

METHODS

Blood samples obtained from glioma patients were collected after surgery prior to the adjuvant therapy. cfDNA was extracted from plasma and IDH1 p.R132H mutation analysis was performed on a digital droplet PCR. χ2-test and Cohen k were used to assess the correlation between plasma and tissue IDH1 status, while Kaplan Meier curve and Cox regression analysis were applied to survival analysis. Statistical calculations were performed by MedCalc and GraphPad Prism software.

RESULTS

A total of 67 samples were collected. A concordance between IDH1 status in tissue and in plasma was found (p = 0.0024), and the presence of the IDH1 mutation both in tissue (138.8 months vs 24.4, p < 0.0001) and cfDNA (116.3 months vs 35.8, p = 0.016) was associated with longer median OS. A significant association between IDH1 mutation both in tissue and cfDNA, age, tumor grade and OS was demonstrated by univariate Cox regression analysis. No statistically significant association between IDH1 mutation and tumor grade was found (p = 0.10).

CONCLUSIONS

The present study demonstrates that liquid biopsy may be used in brain tumors to detect IDH1 mutation which represents an important prognostic biomarker in patients with different types of gliomas, being associated to OS.

Revisiting the Role of B-RAF Kinase as a Therapeutic Target in Melanoma

Malignant melanoma is the rarest but most aggressive and deadly skin cancer. Melanoma is the result of a malignant transformation of melanocytes, which leads to their uncontrolled proliferation. Mutations in the mitogen-activated protein kinase (MAPK) pathway, which are crucial for the control of cellular processes, such as apoptosis, division, growth, differentiation, and migration, are one of its most common causes. BRAF kinase, as one of the known targets of this pathway, has been known for many years as a prominent molecular target in melanoma therapy, and the following mini-review outlines the state-of-the-art knowledge regarding its structure, mutations and mechanisms.

Promising and Minimally Invasive Biomarkers: Targeting Melanoma

The therapeutic landscape of malignant melanoma has been radically reformed in recent years, with novel treatments emerging in both the field of cancer immunotherapy and signalling pathway inhibition. Large-scale tumour genomic characterization has accurately classified malignant melanoma into four different genomic subtypes so far. Despite this, only somatic mutations in BRAF oncogene, as assessed in tumour biopsies, has so far become a validated predictive biomarker of treatment with small molecule inhibitors. The biology of tumour evolution and heterogeneity has uncovered the current limitations associated with decoding genomic drivers based only on a single-site tumour biopsy. There is an urgent need to develop minimally invasive biomarkers that accurately reflect the real-time evolution of melanoma and that allow for streamlined collection, analysis, and interpretation. These will enable us to face challenges with tumour tissue attainment and process and will fulfil the vision of utilizing "liquid biopsy" to guide clinical decisions, in a manner akin to how it is used in the management of haematological malignancies. In this review, we will summarize the most recent published evidence on the role of minimally invasive biomarkers in melanoma, commenting on their future potential to lead to practice-changing discoveries.

Deep learning-based scoring of tumour-infiltrating lymphocytes is prognostic in primary melanoma and predictive to PD-1 checkpoint inhibition in melanoma metastases

BACKGROUND

Recent advances in digital pathology have enabled accurate and standardised enumeration of tumour-infiltrating lymphocytes (TILs). Here, we aim to evaluate TILs as a percentage electronic TIL score (eTILs) and investigate its prognostic and predictive relevance in cutaneous melanoma.

METHODS

We included stage I to IV cutaneous melanoma patients and used hematoxylin-eosin-stained slides for TIL analysis. We assessed eTILs as a continuous and categorical variable using the published cut-off of 16.6% and applied Cox regression models to evaluate associations of eTILs with relapse-free, distant metastasis-free, and overall survival. We compared eTILs of the primaries with matched metastasis. Moreover, we assessed the predictive relevance of eTILs in therapy-naïve metastases according to the first-line therapy.

FINDINGS

We analysed 321 primary cutaneous melanomas and 191 metastatic samples. In simple Cox regression, tumour thickness (p < 0.0001), presence of ulceration (p = 0.0001) and eTILs ≤16.6% (p = 0.0012) were found to be significant unfavourable prognostic factors for RFS. In multiple Cox regression, eTILs ≤16.6% (p = 0.0161) remained significant and downgraded the current staging. Lower eTILs in the primary tissue was associated with unfavourable relapse-free (p = 0.0014) and distant metastasis-free survival (p = 0.0056). In multiple Cox regression adjusted for tumour thickness and ulceration, eTILs as continuous remained significant (p = 0.019). When comparing TILs in primary tissue and corresponding metastasis of the same patient, eTILs in metastases was lower than in primary melanomas (p < 0.0001). In therapy-naïve metastases, an eTILs >12.2% was associated with longer progression-free survival (p = 0.037) and melanoma-specific survival (p = 0.0038) in patients treated with anti-PD-1-based immunotherapy. In multiple Cox regression, lactate dehydrogenase (p < 0.0001) and eTILs ≤12.2% (p = 0.0130) were significantly associated with unfavourable melanoma-specific survival.

INTERPRETATION

Assessment of TILs is prognostic in primary melanoma samples, and the eTILs complements staging. In therapy-naïve metastases, eTILs ≤12.2% is predictive of unfavourable survival outcomes in patients receiving anti-PD-1-based therapy.

FUNDING

See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript.

Early decrease of blood myeloid-derived suppressor cells during checkpoint inhibition is a favorable biomarker in metastatic melanoma

BACKGROUND

The need for reliable clinical biomarkers to predict which patients with melanoma will benefit from immune checkpoint blockade (ICB) remains unmet. Several different parameters have been considered in the past, including routine differential blood counts, T cell subset distribution patterns and quantification of peripheral myeloid-derived suppressor cells (MDSC), but none has yet achieved sufficient accuracy for clinical utility.

METHODS

Here, we investigated potential cellular biomarkers from clinical routine blood counts as well as several myeloid and T cell subsets, using flow cytometry, in two independent cohorts of a total of 141 patients with stage IV M1c melanoma before and during ICB.

RESULTS

Elevated baseline frequencies of monocytic MDSCs (M-MDSC) in the blood were confirmed to predict shorter overall survival (OS) (HR 2.086, p=0.030) and progression-free survival (HR 2.425, p=0.001) in the whole patient cohort. However, we identified a subgroup of patients with highly elevated baseline M-MDSC frequencies that fell below a defined cut-off during therapy and found that these patients had a longer OS that was similar to that of patients with low baseline M-MDSC frequencies. Importantly, patients with high M-MDSC frequencies exhibited a skewed baseline distribution of certain other immune cells but these did not influence patient survival, illustrating the paramount utility of MDSC assessment.

CONCLUSION

We confirmed that in general, highly elevated frequencies of peripheral M-MDSC are associated with poorer outcomes of ICB in metastatic melanoma. However, one reason for an imperfect correlation between high baseline MDSCs and outcome for individual patients may be the subgroup of patients identified here, with rapidly decreasing M-MDSCs on therapy, in whom the negative effect of high M-MDSC frequencies was lost. These findings might contribute to developing more reliable predictors of late-stage melanoma response to ICB at the individual patient level. A multifactorial model seeking such markers yielded only MDSC behavior and serum lactate dehydrogenase as predictors of treatment outcome.

Circulating tumor DNA-based molecular residual disease detection for treatment monitoring in advanced melanoma patients

BACKGROUND

Immune checkpoint inhibitors (ICIs) have substantially improved overall survival in patients with advanced melanoma; however, the lack of biomarkers to monitor treatment response and relapse remains an important clinical challenge. Thus, a reliable biomarker is needed that can risk-stratify patients for disease recurrence and predict response to treatment.

METHODS

A retrospective analysis using a personalized, tumor-informed circulating tumor DNA (ctDNA) assay on prospectively collected plasma samples (n = 555) from 69 patients with advanced melanoma was performed. Patients were divided into three cohorts: cohort A (N = 30), stage III patients receiving adjuvant ICI/observation; cohort B (N = 29), unresectable stage III/IV patients receiving ICI therapy; and cohort C (N = 10), stage III/IV patients on surveillance after planned completion of ICI therapy for metastatic disease.

RESULTS

In cohort A, compared to molecular residual disease (MRD)-negative patients, MRD-positivity was associated with significantly shorter distant metastasis-free survival (DMFS; hazard ratio [HR], 10.77; p = .01). Increasing ctDNA levels from the post-surgical or pre-treatment time point to after 6 weeks of ICI were predictive of shorter DMFS in cohort A (HR, 34.54; p < .0001) and shorter progression-free survival (PFS) in cohort B (HR, 22; p = .006). In cohort C, all ctDNA-negative patients remained progression-free for a median follow-up of 14.67 months, whereas ctDNA-positive patients experienced disease progression.

CONCLUSION

Personalized and tumor-informed longitudinal ctDNA monitoring is a valuable prognostic and predictive tool that may be used throughout the clinical course of patients with advanced melanoma.

Shaping the Future of Immunotherapy Targets and Biomarkers in Melanoma and Non-Melanoma Cutaneous Cancers

Recent advances in treating cutaneous melanoma have resulted in impressive patient survival gains. Refinement of disease staging and accurate patient risk classification have significantly improved our prognostic knowledge and ability to accurately stratify treatment. Undoubtedly, the most important step towards optimizing patient outcomes has been the advent of cancer immunotherapy, in the form of immune checkpoint inhibition (ICI). Immunotherapy has established its cardinal role in the management of both early and late-stage melanoma. Through leveraging outcomes in melanoma, immunotherapy has also extended its benefit to other types of skin cancers. In this review, we endeavor to summarize the current role of immunotherapy in melanoma and non-melanoma skin cancers, highlight the most pertinent immunotherapy-related molecular biomarkers, and lastly, shed light on future research directions.

The Role of Cell-Free DNA in Cancer Treatment Decision Making

The aim of this review is to evaluate the present status of the use of cell-free DNA and its fraction of circulating tumor DNA (ctDNA) because this year July 2022, an ESMO guideline was published regarding the application of ctDNA in patient care. This review is for clinical oncologists to explain the concept, the terms used, the pros and cons of ctDNA; thus, the technical aspects of the different platforms are not reviewed in detail, but we try to help in navigating the current knowledge in liquid biopsy. Since the validated and adequately sensitive ctDNA assays have utility in identifying actionable mutations to direct targeted therapy, ctDNA may be used for this soon in routine clinical practice and in other different areas as well. The cfDNA fragments can be obtained by liquid biopsy and can be used for diagnosis, prognosis, and selecting among treatment options in cancer patients. A great proportion of cfDNA comes from normal cells of the body or from food uptake. Only a small part (<1%) of it is related to tumors, originating from primary tumors, metastatic sites, or circulating tumor cells (CTCs). Soon the data obtained from ctDNA may routinely be used for finding minimal residual disease, detecting relapse, and determining the sites of metastases. It might also be used for deciding appropriate therapy, and/or emerging resistance to the therapy and the data analysis of ctDNA may be combined with imaging or other markers. However, to achieve this goal, further clinical validations are inevitable. As a result, clinicians should be aware of the limitations of the assays. Of course, several open questions are still under research and because of it cfDNA and ctDNA testing are not part of routine care yet.

Unravelling Tumour Microenvironment in Melanoma at Single-Cell Level and Challenges to Checkpoint Immunotherapy

Melanoma is known as one of the most immunogenic tumours and is often characterised by high mutation burden, neoantigen load and immune infiltrate. The application of immunotherapies has led to impressive improvements in the clinical outcomes of advanced stage melanoma patients. The standard of care immunotherapies leverage the host immunological influence on tumour cells, which entail complex interactions among the tumour, stroma, and immune cells at the tumour microenvironmental level. However, not all cancer patients can achieve a long-term durable response to immunotherapy, and a significant proportion of patients develops resistance and still die from their disease. Owing to the multi-faceted problems of tumour and microenvironmental heterogeneity, identifying the key factors underlying tumour progression and immunotherapy resistance poses a great challenge. In this review, we outline the main challenges to current cancer immunotherapy research posed by tumour heterogeneity and microenvironment complexities including genomic and transcriptomic variability, selective outgrowth of tumour subpopulations, spatial and temporal tumour heterogeneity and the dynamic state of host immunity and microenvironment orchestration. We also highlight the opportunities to dissect tumour heterogeneity using single-cell sequencing and spatial platforms. Integrative analyses of large-scale datasets will enable in-depth exploration of biological questions, which facilitates the clinical application of translational research.

The Prognostic Value of a Single, Randomly Timed Circulating Tumor DNA Measurement in Patients with Metastatic Melanoma

Simple Summary

In this study, we investigated the associations of circulating tumor DNA (ctDNA), measured at a random time point during the patient’s treatment, with tumor progression and routine blood markers (protein S100, lactate dehydrogenase (LDH), and C-reactive protein (CRP)) in a cohort of patients with metastatic melanoma. Detectable ctDNA was associated with the presence of extracerebral disease, tumor progression, and poorer overall survival (OS). Elevated S100 and CRP was correlated with detectable ctDNA, whereas LDH was not. Our results further support the use of ctDNA in the clinical management of patients with metastatic melanoma.

Abstract

Melanoma currently lacks validated blood-based biomarkers for monitoring and predicting treatment efficacy. Circulating tumor DNA (ctDNA), originating from tumor cells and detectable in plasma, has emerged as a possible biomarker in patients with metastatic melanoma. In this retrospective, single-center study, we collected 129 plasma samples from 79 patients with stage IIIB–IV melanoma as determined by the American Joint Committee on Cancer (AJCC, 8th edition). For the determination of ctDNA levels, we used eight different assays of droplet digital polymerase chain reaction (ddPCR) to detect the most common hotspot mutations in the BRAF and NRAS genes. The aim of the study was to investigate the association of the detectability of ctDNA at a non-prespecified time point in a patient’s treatment with tumor progression, and to correlate ctDNA with commonly used biomarkers (protein S100, LDH, and CRP). Patients with detectable ctDNA progressed more frequently in PET-CT within 12 months than those without detectable ctDNA. Detectability of ctDNA was associated with shorter OS in univariate and multivariate analyses. ctDNA was detectable in a statistically significantly larger proportion of patients with distant metastases (79%) than in patients with no distant metastases or only intracranial metastases (32%). Elevated protein S100 and CRP correlated better with detectable ctDNA than LDH. This study supports the potential of ctDNA as a prognostic biomarker in patients with metastatic melanoma. However, additional prospective longitudinal studies with quantitative assessments of ctDNA are necessary to investigate the limitations and strengths of ctDNA as a biomarker.

Serum cell-free DNA as a new biomarker in cutaneous T-cell lymphoma

In recent years, circulating cell-free DNA (cfDNA) has received a great attention as a biomarker for various cancers. Many reports have shown that serum cfDNA levels are elevated in cancer patients and their levels correlate with prognosis and disease activity. The aim of this study was to measure serum cfDNA levels in patients with cutaneous T-cell lymphoma (CTCL) and to evaluate their correlations with hematological and clinical findings. Serum cfDNA levels in CTCL patients were significantly higher than those in healthy controls, and their levels gradually increased with the progression of the disease stage. Positive correlations were detected between serum cfDNA levels and those of lactate dehydrogenase, thymus and activation-regulated chemokine and soluble IL-2 receptor as well as neutrophil and eosinophil count in peripheral blood and neutrophil-to-lymphocyte ratio. Furthermore, CTCL patients with higher serum cfDNA levels exhibited a significantly worse prognosis. Taken together, these results suggest the potential of cfDNA as a new biomarker reflecting prognosis and disease activity in CTCL. CfDNA levels may serve as an indicator for considering the intensity and timing of subsequent therapeutic intervention.