Quantitative measurement of melanoma spread in sentinel lymph nodes and survival

How much do we know about the metastatic process?

Cancer cells can leave their primary sites and travel through the circulation to distant sites, where they lodge as disseminated cancer cells (DCCs), even during the early and asymptomatic stages of tumor progression. In experimental models and clinical samples, DCCs can be detected in a non-proliferative state, defined as cellular dormancy. This state can persist for extended periods until DCCs reawaken, usually in response to niche-derived reactivation signals. Therefore, their clinical detection in sites like lymph nodes and bone marrow is linked to poor survival. Current cancer therapy designs are based on the biology of the primary tumor and do not target the biology of the dormant DCC population and thus fail to eradicate the initial or subsequent waves of metastasis. In this brief review, we discuss the current methods for detecting DCCs and highlight new strategies that aim to target DCCs that constitute minimal residual disease to reduce or prevent metastasis formation. Furthermore, we present current evidence on the relevance of DCCs derived from early stages of tumor progression in metastatic disease and describe the animal models available for their study. We also discuss our current understanding of the dissemination mechanisms utilized by genetically less- and more-advanced cancer cells, which include the functional analysis of intermediate or hybrid states of epithelial-mesenchymal transition (EMT). Finally, we raise some intriguing questions regarding the clinical impact of studying the crosstalk between evolutionary waves of DCCs and the initiation of metastatic disease.

Isolated melanoma cells in sentinel lymph node in stage IIIA melanoma correlate with a favorable prognosis similar to stage IB

BACKGROUND

The American Joint Committee on Cancer 8th edition (AJCC v8) defines sentinel lymph nodes (SLN) containing any tumor cells as positive SLN. Consequently, even thin melanomas with isolated tumor cells (ic) in SLN are classified as stage IIIA, making them candidates for adjuvant therapy.

OBJECTIVES AND ENDPOINTS

We aimed to evaluate survival outcomes of melanoma stage IIIA (ic) and compare them with stage IIIA with lymph node (LN) metastases > 0.1 mm. Primary endpoints were relapse-free survival (RFS) and distant metastases-free survival (DMFS). Secondary endpoint was melanoma specific survival (MSS).

RESULTS

The discovery cohort from the Department of Dermatology, University Hospital Tuebingen, included 237 patients; confirmation cohort included 143 patients from the DeCOG trial. The Tuebingen cohort included 95 patients with stage IIIA (ic) and 142 patients with stage IIIA. The DeCOG trial included 39 patients with stage IIIA (ic) and 104 patients with stage IIIA. In the Tuebingen cohort, 10-year RFS rates for stage IIIA (ic) and IIIA were 84% (95% CI 75-94) and 49% (95% CI 39-59), respectively (p < 0.001). 10-year DMFS rates for stage IIIA (ic) and IIIA were 89% (95% CI 81-97) and 56% (95% CI 45-67), respectively; (p < 0.001). In the DeCOG cohort, 10-year RFS for stage IIIA (ic) and stage IIIA were 88% (95% CI 78-99) and 35% (95% CI 7-62), respectively; (p = 0.009). 10-year DMFS for stage IIIA (ic) and IIIA was 88% (95% CI 77-99) and 60% (95% CI 39-80), respectively (p = 0.061).

CONCLUSION

Stage IIIA (ic) melanoma exhibits a prognosis similar to stage IB. Recommendation of adjuvant therapy in Stage IIIA (ic) warrants thorough discussion.

Dormancy of cutaneous melanoma

Many cancer-related deaths including melanoma result from metastases that develop months or years after the initial cancer therapy. Even the most effective drugs and immune therapies rarely eradicate all tumor cells. Instead, they strongly reduce cancer burden, permitting dormant cancer cells to persist in niches, where they establish a cellular homeostasis with their host without causing clinical symptoms. Dormant cancers respond poorly to most drugs and therapies since they do not proliferate and hide in niches. It therefore remains a major challenge to develop novel therapies for dormant cancers. In this review we focus on the mechanisms regulating the initiation of cutaneous melanoma dormancy as well as those which are involved in reawakening of dormant cutaneous melanoma cells. In recent years the role of neutrophils and niche components in reawakening of melanoma cells came into focus and indicate possible future therapeutic applications. Sophisticated in vitro and in vivo melanoma dormancy models are needed to make progress in this field and are discussed.

Macrophages Promote Subtype Conversion and Endocrine Resistance in Breast Cancer

BACKGROUND

The progression of tumors from less aggressive subtypes to more aggressive states during metastasis poses challenges for treatment strategies. Previous studies have revealed the molecular subtype conversion between primary and metastatic tumors in breast cancer (BC). However, the subtype conversion during lymph node metastasis (LNM) and the underlying mechanism remains unclear.

METHODS

We compared clinical subtypes in paired primary tumors and positive lymph nodes (PLNs) in BC patients and further validated them in the mouse model. Bioinformatics analysis and macrophage-conditioned medium treatment were performed to investigate the role of macrophages in subtype conversion.

RESULTS

During LNM, hormone receptors (HRs) were down-regulated, while HER2 was up-regulated, leading to the transformation of luminal A tumors towards luminal B tumors and from luminal B subtype towards HER2-enriched (HER2-E) subtype. The mouse model demonstrated the elevated levels of HER2 in PLN while retaining luminal characteristics. Among the various cells in the tumor microenvironment (TME), macrophages were the most clinically relevant in terms of prognosis. The treatment of a macrophage-conditioned medium further confirmed the downregulation of HR expression and upregulation of HER2 expression, inducing tamoxifen resistance. Through bioinformatics analysis, MNX1 was identified as a potential transcription factor governing the expression of HR and HER2.

CONCLUSION

Our study revealed the HER2-E subtype conversion during LNM in BC. Macrophages were the crucial cell type in TME, inducing the downregulation of HR and upregulation of HER2, probably via MNX1. Targeting macrophages or MNX1 may provide new avenues for endocrine therapy and targeted treatment of BC patients with LNM.

Sentinel lymph node biopsy for lentigo maligna melanoma under local anaesthesia

BACKGROUND

Lentigo maligna melanoma is mainly localized in the head and neck region in elderly patients. Due to its slow horizontal growth, it has a good prognosis compared to other melanoma subtypes, but specific data are rare.

OBJECTIVES

The aim of this study was to investigate sentinel lymph node biopsy in lentigo maligna melanoma under local anaesthesia and to discuss the benefit.

METHODS

Investigation of patients with lentigo maligna melanoma and tumour thickness ≥1 mm treated at the Department of Dermatology, University Medical Centre Tuebingen, between January 2008 and October 2019.

RESULTS

In total, 204 patients (126 SLNB, 78 non-SLNB) with a median age of 75.7 years (SLNB: 73.3 years, non-SLNB: 79.7 years) could be included. Sixteen of 126 (12.7%) sentinel lymph nodes were positive. Five-year overall survival was 87.9% (88.5% SLNB; 87.4% non-SLNB) and 5-year distant metastasis-free survival was 85.8% (85.4% SLNB; 86.7% non-SLNB). There was no significant difference for distant metastasis-free survival (p = 0.861) and overall survival (p = 0.247) between patients with and without sentinel lymph node biopsy.

CONCLUSIONS

Sentinel lymph node biopsy in lentigo maligna melanoma under local anaesthesia is a safe and simple method, even in very old patients. However, LMM has a very good 5-year overall survival. In high-risk patients with high tumour thickness and/or ulceration, adjuvant immunotherapy can now be offered without the need to perform this procedure.

Ex vivo expansion of lung cancer-derived disseminated cancer cells from lymph nodes identifies cells associated with metastatic progression

The cellular basis of the apparent aggressiveness in lung cancer is poorly understood but likely associated with functional or molecular features of disseminated cancer cells (DCCs). DCCs from epithelial cancers are mostly detected by antibodies directed against histogenetic markers such as cytokeratin or EpCAM. It has been argued that marker-negative metastatic founder cells might escape detection. We therefore used ex vivo sphere formation for functional detection of candidate metastasis founders. We generated cell suspensions from 199 LN samples of 131 lung cancer patients and placed them into non-adherent cell culture. Sphere formation was associated with detection of DCCs using EpCAM immunocytology and with significantly poorer prognosis. The prognostic impact of sphere formation was strongly associated with high numbers of EpCAM-positive DCCs and aberrant genotypes of expanded spheres. We also noted sphere formation in patients with no evidence of lymphatic spread, however such spheres showed infrequent expression of signature genes associated with spheres from EpCAM-positive samples and displayed neither typical lung cancer mutations (KRAS, TP53, ERBB1) nor copy number variations, but might be linked to disease progression >5 years post curative surgery. We conclude that EpCAM identifies relevant disease-driving DCCs, that such cells can be expanded for model generation and that further research is needed to clarify the functional and prognostic role of rare EpCAM-negative sphere forming cells.

Construction, validation and, visualization of a web-based nomogram to identify the best candidates for primary tumor resection in advanced cutaneous melanoma patients

Background

Existing studies have shown whether primary site resection (PSR) in cutaneous melanoma (CM) patients with stage IV is controversial. Our study aimed to identify the clinical characteristics of CM patients with stage IV who benefited from PSR on a population-based study.

Methods

We retrospectively reviewed stage IV CM patients in the Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2015. Patients were divided into surgical and non-surgical groups according to whether PSR was performed or not. According to the median cancer-specific survival (CSS) time of the non-surgery group, the surgical group was divided into the surgery-benefit group and the non-surgery-benefit group. Multivariate cox regression analysis was used to explore independent CSS prognostic factors in the surgical group. Then, based on the independent prognostic factors of the surgical group, we established a web-based nomogram based on logistics regression.

Results

A total of 574 stage IV CM patients were included in our study, and 491 (85.60%) patients were included in the surgical group. The clinical characteristics (benefit group and non-benefit group) included age, M stage, lesion location, and ulceration status. These independent prognostic factors were includeed to construct a web-based nomogram.

Conclusions

We constructed a web-based nomogram. This model was suitable for identifying the best candidates suitable for PSR in stage IV CM patients.

TMB and BRAF mutation status are independent predictive factors in high-risk melanoma patients with adjuvant anti-PD-1 therapy

BACKGROUND

High tumor mutational burden (TMB) is associated with a favorable outcome in metastatic melanoma patients treated with immune checkpoint inhibitors. However, data are limited in the adjuvant setting. As BRAF mutated patients have an alternative with targeted adjuvant therapy, it is important to identify predictive factors for relapse and recurrence-free survival (RFS) in patients receiving adjuvant anti-PD-1 antibodies.

METHODS

We evaluated 165 melanoma patients who started adjuvant anti-PD-1 antibody therapy at our center between March 2018 and September 2019. The initial tumor stage was assessed at the beginning of therapy according to the 8th edition of the AJCC Cancer Staging Manual. Tumor and normal tissue of the high-risk stages IIIC/D/IV were sequenced using a 700 gene NGS panel.

RESULTS

The tumor stages at the beginning of adjuvant anti-PD-1 therapy were as follows: N = 80 stage IIIA/B (48%), N = 85 stage IIIC/D/IV (52%). 72/165 patients (44%) suffered a relapse, 44/72 (61%) with only loco regional and 28/72 (39%) with distant metastases. Sequencing results were available from 83 to 85 patients with stage IIIC/D/IV. BRAF mutation status (HR 2.12, 95% CI 1.12-4.08; p = 0.022) and TMB (HR 7.11, 95% CI 2.19-23.11; p = 0.001) were significant and independent predictive factors for relapse-free survival (RFS).

CONCLUSION

BRAF mutation status and TMB were independent predictive factors for RFS. Patients with BRAF V600E/K mutation and TMB high had the best outcome. A classification based on BRAF mutation status and TMB is proposed to predict RFS in melanoma patients with adjuvant anti-PD-1 therapy.

Reporting of melanoma cell densities in the sentinel node refines outcome prediction

INTRODUCTION

Sentinel node biopsy is a key procedure to predict prognosis in melanoma. In a prospective study we compare reporting on melanoma cell densities in cytospin preparations with semiquantitative histopathology for predicting outcome.

PATIENTS AND METHODS

Sentinel nodes from 900 melanoma patients were bisected. One half of each node was disaggregated mechanically. The melanoma cell density (number of HMB45 positive cells per million lymphocytes with at least one cell showing morphological features of a melanoma cell) was recorded after examining two cytospins. For the second half the maximum diameter of metastasis was determined after haematoxylin and eosin (H&E) and immunohistological staining of three slides.

RESULTS

Cytospins were positive for melanoma in 218 of 900 patients (24%). Routine pathology was positive in 111 of 900 (12%) patients. A more extensive pathological workup in cytospin-only positive patients led to a revised diagnosis (from negative to positive) in 23 of 101 patients (22.7%). We found a moderate but significant correlation between melanoma cell densities (determined in cytospins) and the maximum diameter of metastasis (determined by pathology) (rho = 0.6284, p < 0.001). At a median follow-up of 37 months (IQR 25-53 months) melanoma cell density (cytospins) (p < 0.001), thickness of melanoma (p = 0.008) and ulceration status (p = 0.026) were significant predictors for melanoma specific survival by multivariable testing and were all confirmed as key predictive factors by the random forest model. Maximum diameter of metastases, age and sex were not significant by multivariable testing (all p > 0.05).

CONCLUSION

Recording melanoma cell densities by examining two cytospins accurately predicts melanoma outcome and outperforms semiquantitative histopathology.

Evaluation of Anticancer Potential of Flavones from Rhamnus alaternus against B16F10 Melanoma Cells

Melanoma has become an important health problem and new treatment have become an imperative medical need. Therefore, the finding and identification of natural product with less toxic effects, capable of promoting melanoma cell death have become an important goal of research in oncotherapy. In this study, we want to investigate the anticancer activity of an enriched total oligomers flavonoids (TOF) extract of R. alaternus in melanoma cells. First, TOF was exhibited to be rich in flavones. We revealed that this extract reduced proliferation and increased of sub-G1 and S phase cells built-up in B16-F10 cells in a dose-related manner. Moreover, In Vivo, TOF reduced tumor volume and weight with percentages of inhibition of 92.4% and 92.9%, respectively. R. alaternus was also found to be effective in reducing the level of pro-inflammatory cytokine IL-6 during metastasis. Level of TH1 cytokine, such as IL-2, was significantly enhanced by TOF treatment. Indeed, the histological examination of the tumor revealed the absence of mitoses and the presence of numerous melanin pigmented macrophage cells in the R. alaternus extract-treated group that could be explained by the induction of macrophage activation and by the arrest of the cell cycle in the Sub-G1 and S phases.

mRNA-Based Cancer Vaccines: A Therapeutic Strategy for the Treatment of Melanoma Patients

Malignant melanoma is one of the most aggressive forms of cancer and the leading cause of death from skin tumors. Given the increased incidence of melanoma diagnoses in recent years, it is essential to develop effective treatments to control this disease. In this regard, the use of cancer vaccines to enhance cell-mediated immunity is considered to be one of the most modern immunotherapy options for cancer treatment. The most recent cancer vaccine options are mRNA vaccines, with a focus on their usage as modern treatments. Advantages of mRNA cancer vaccines include their rapid production and low manufacturing costs. mRNA-based vaccines are also able to induce both humoral and cellular immune responses. In addition to the many advantages of mRNA vaccines for the treatment of cancer, their use is associated with a number of challenges. For this reason, before mRNA vaccines can be used for the treatment of cancer, comprehensive information about them is required and a large number of trials need to be conducted. Here, we reviewed the general features of mRNA vaccines, including their basis, stabilization, and delivery methods. We also covered clinical trials involving the use of mRNA vaccines in melanoma cancer and the challenges involved with this type of treatment. This review also emphasized the combination of treatment with mRNA vaccines with the use of immune-checkpoint blockers to enhance cell-mediated immunity.

Retrospective cell lineage reconstruction in humans by using short tandem repeats

Cell lineage analysis aims to uncover the developmental history of an organism back to its cell of origin. Recently, novel in vivo methods utilizing genome editing enabled important insights into the cell lineages of animals. In contrast, human cell lineage remains restricted to retrospective approaches, which still lack resolution and cost-efficient solutions. Here, we demonstrate a scalable platform based on short tandem repeats targeted by duplex molecular inversion probes. With this human cell lineage tracing method, we accurately reproduced a known lineage of DU145 cells and reconstructed lineages of healthy and metastatic single cells from a melanoma patient who matched the anatomical reference while adding further refinements. This platform allowed us to faithfully recapitulate lineages of developmental tissue formation in healthy cells. In summary, our lineage discovery platform can profile informative somatic mutations efficiently and provides solid lineage reconstructions even in challenging low-mutation-rate healthy single cells.

Post-operative follow-up of 150 patients with sentinel lymph node biopsy under tumescence local anesthesia

BACKGROUND

Sentinel lymph node biopsy (SLNB) is useful for staging of patients with melanoma. Although SLNB is mostly performed under general anesthesia (GA), tumescence local anesthesia (TLA) can also be used. However, less data are available regarding feasibility of SLNB under TLA. Here we present a post-operative follow-up of 150 patients.

PATIENTS AND METHODS

We prospectively analyzed data from 150 patients with primary cutaneous malignant melanoma. We assessed pain, post-operative complications and patients' satisfaction after SLNB under TLA.

RESULTS

32 % of the patients reported post-operative pain within the first 48 h after SLNB. Seroma was the most frequent complication, as 29 seromas after SLNB were observed. Wound infection was observed in 3.3 % of the patients. 98.7 % of the patients were satisfied with SLNB under TLA.

CONCLUSIONS

SLNB under TLA is a safe and feasible option and should be considered for patients with melanoma. Especially with multimorbid or elderly patients, the risks of GA can be avoided.

Cancer progression and the invisible phase of metastatic colonization

Metastatic dissemination occurs very early in the malignant progression of a cancer but the clinical manifestation of metastases often takes years. In recent decades, 5-year survival of patients with many solid cancers has increased due to earlier detection, local disease control and adjuvant therapies. As a consequence, we are confronted with an increase in late relapses as more antiproliferative cancer therapies prolong disease courses, raising questions about how cancer cells survive, evolve or stop growing and finally expand during periods of clinical latency. I argue here that the understanding of early metastasis formation, particularly of the currently invisible phase of metastatic colonization, will be essential for the next stage in adjuvant therapy development that reliably prevents metachronous metastasis.

Flow Cytometry for Detection and Quantification of Micrometastases in Sentinel Lymph Nodes from Patients with Primary Melanoma

BACKGROUND

Detection of micrometastases in the regional lymph nodes is one of the most important prognostic factors for melanoma patients. Our aim was to evaluate the suitability of flow cytometry for rapid quantification of disseminated melanoma cells in sentinel lymph nodes (SLN).

METHODS

132 SLNs from 104 patients diagnosed with melanoma were analyzed by flow cytometry, utilizing the extracellular marker melanoma-associated chondroitin sulfate proteoglycan, in addition to quantitative immunocytology and conventional histopathology, including immunohistochemistry. For quantification, the number of melanoma-positive cells per million lymph node cells (disseminated cancer cell density, DCCD) detected by flow cytometry was compared to the DCCD obtained by immunocytology.

RESULTS

Compared to histopathology and immunocytology, flow cytometry exhibited a sensitivity of 50% and a specificity of 85%. DCCDs of immunocytology and flow cytometry of the 37 immunocytologically positive SLNs showed a positive correlation (Spearman's ρ = 0.7, P < 0.0001). In 10 SLNs from 9 patients with high tumor load, the flow cytometric DCCD was 8-fold higher on average than the immunocytologic DCCD.

CONCLUSIONS

Although flow cytometry is not yet suitable for early detection of metastatic melanoma, it promises to become a valuable tool for rapidly quantifying tumor load in high-risk patients.

Clinical significance of SLN benign capsular nevi in patients with melanoma

BACKGROUND

Benign capsular nevi (BCN) are not infrequent in sentinel lymph nodes (SLN) of patients with melanoma. Their prognostic significance is unknown and the literature is limited. This study evaluated the clinical significance of incidentally found BCN in these patients.

METHODS

A multi-institutional retrospective review of patients undergoing SLN biopsy for cutaneous melanoma between 2000 and 2016. Patients were divided into the following groups: (a) negative SLN and no BCN, (b) negative SLN and presence of BCN, (c) positive SLN seen only on immunohistochemistry (IHC), and (d) positive SLN via hematoxylin and eosin (H&E). Outcomes measured were overall survival and any recurrence.

RESULTS

A total of 1253 patients were identified (group 1 = 978, group 2 = 56, group 3 = 32, and group 4 = 187). Fifty-seven percent were male and the mean age was 59.3 years. BCN was identified in 77 patients (6.2%), of which the majority was in the node-negative group (72%). Multivariable analysis showed that BCN was associated with lower recurrence rates, though not statistically significant (hazard ratio [HR] = 0.5; P = .06). IHC- and H&E-positive SLNs were associated with a higher risk of recurrence (HR = 2.4; P = .02 and 2.0, P < .0001, respectively).

CONCLUSION

Patients with BCN and negative SLN had lower recurrence rates than patients with negative SLN and no BCN. Our data suggest a possible protective effect against recurrence.

[Sentinel node biopsy and lymph node dissection in the era of new systemic therapies for malignant melanoma]

BACKGROUND

Recently, adjuvant therapies with checkpoint inhibitors and BRAF/MEK inhibitors have become available for patients with malignant melanoma and microscopic nodal disease. Meanwhile the number of complete nodal dissections for a melanoma-positive sentinel node (SN) have decreased significantly.

OBJECTIVE

The authors discuss the significance of sentinel node biopsy (SNB) and early lymph node dissection in the era of adjuvant systemic therapy for stage III melanoma.

MATERIALS AND METHODS

Current publications and recommendations were evaluated.

RESULTS

Complete nodal dissection for a positive SN significantly reduces the risk of regional nodal relapse. However, neither SNB nor complete nodal dissection following a positive SN are associated with a benefit in survival. With the availability of novel adjuvant systemic treatment strategies for stage III melanoma, SNB has become an even more important part of modern staging diagnostics. Thus, detection of early dissemination of melanoma cells into the SN as well as the quantification of the tumor load are decisive for further therapy planning.

CONCLUSION

Accurate assessment of the regional lymph node status by SNB is becoming even more important in the era of novel effective adjuvant therapies for microscopic nodal disease. Whether complete lymph node dissection is performed in patients with a positive SN needs to be assessed individually. In the case of "active nodal surveillance" instead of surgery, long-term close follow-up in specialized centers, including ultrasonographic controls, is required.

Histone deacetylase 11 inhibition promotes breast cancer metastasis from lymph nodes

Lymph node (LN) metastases correspond with a worse prognosis in nearly all cancers, yet the occurrence of cancer spreading from LNs remains controversial. Additionally, the mechanisms explaining how cancers survive and exit LNs are largely unknown. Here, we show that breast cancer patients frequently have LN metastases that closely resemble distant metastases. In addition, using a microsurgical model, we show how LN metastasis development and dissemination is regulated by the expression of a chromatin modifier, histone deacetylase 11 (HDAC11). Genetic and pharmacologic blockade of HDAC11 decreases LN tumor growth, yet substantially increases migration and distant metastasis formation. Collectively, we reveal a mechanism explaining how HDAC11 plasticity promotes breast cancer growth as well as dissemination from LNs and suggest caution with the use of HDAC inhibitors.

The prognosis of cancer patients with lymph node (LN) metastasis is worse than those without. Here, the authors report that while histone deacetylase 11 (HDAC11) inhibition suppresses tumor growth within the LN, it also promotes cancer cell migration out of the LN to form distant metastasis, and therefore suggest caution with HDAC inhibitors.

Microfluidic enrichment, isolation and characterization of disseminated melanoma cells from lymph node samples

For the first time in melanoma, novel therapies have recently shown efficacy in the adjuvant therapy setting, which makes companion diagnostics to guide treatment decisions a desideratum. Early spread of disseminated cancer cells (DCC) to sentinel lymph nodes (SLN) is indicative of poor prognosis in melanoma and early DCCs could therefore provide important information about the malignant seed. Here, we present a strategy for enrichment of DCCs from SLN suspensions using a microfluidic device (Parsortix™, Angle plc). This approach enables the detection and isolation of viable DCCs, followed by molecular analysis and identification of genetic changes. By optimizing the workflow, the established protocol allows a high recovery of DCC from melanoma patient-derived lymph node (LN) suspensions with harvest rates above 60%. We then assessed the integrity of the transcriptome and genome of individual, isolated DCCs. In LNs of melanoma patients, we detected the expression of melanoma-associated transcripts including MLANA (encoding for MelanA protein), analyzed the BRAF and NRAS mutational status and confirmed the malignant origin of isolated melanoma DCCs by comparative genomic hybridization. We demonstrate the feasibility of epitope-independent isolation of LN DCCs using Parsortix™ for subsequent molecular characterization of isolated single DCCs with ample application fields including the use for companion diagnostics or subsequent cellular studies in personalized medicine.

Single cell polarity in liquid phase facilitates tumour metastasis

Dynamic polarisation of tumour cells is essential for metastasis. While the role of polarisation during dedifferentiation and migration is well established, polarisation of metastasising tumour cells during phases of detachment has not been investigated. Here we identify and characterise a type of polarisation maintained by single cells in liquid phase termed single-cell (sc) polarity and investigate its role during metastasis. We demonstrate that sc polarity is an inherent feature of cells from different tumour entities that is observed in circulating tumour cells in patients. Functionally, we propose that the sc pole is directly involved in early attachment, thereby affecting adhesion, transmigration and metastasis. In vivo, the metastatic capacity of cell lines correlates with the extent of sc polarisation. By manipulating sc polarity regulators and by generic depolarisation, we show that sc polarity prior to migration affects transmigration and metastasis in vitro and in vivo.

Polarisation of metastasising cancer cells in circulation has not been investigated before. Here the authors identify single cell polarity as a distinct polarisation state of single cells in liquid phase, and show that perturbing single cell polarity affects attachment, adhesion, transmigration and metastasis in vitro and in vivo.

Genetic alterations driving metastatic colony formation are acquired outside of the primary tumour in melanoma

Mouse models indicate that metastatic dissemination occurs extremely early; however, the timing in human cancers is unknown. We therefore determined the time point of metastatic seeding relative to tumour thickness and genomic alterations in melanoma. Here, we find that lymphatic dissemination occurs shortly after dermal invasion of the primary lesion at a median thickness of ~0.5 mm and that typical driver changes, including BRAF mutation and gained or lost regions comprising genes like MET or CDKNA2, are acquired within the lymph node at the time of colony formation. These changes define a colonisation signature that was linked to xenograft formation in immunodeficient mice and death from melanoma. Thus, melanoma cells leave primary tumours early and evolve at different sites in parallel. We propose a model of metastatic melanoma dormancy, evolution and colonisation that will inform direct monitoring of adjuvant therapy targets.

Detection of Minimal Residual Disease and Its Clinical Applications in Melanoma and Breast Cancer Patients

Melanoma and breast cancer (BC) patients face a high risk of recurrence and disease progression after curative surgery and/or therapeutic treatment. Monitoring for minimal residual disease (MRD) during a disease-free follow-up period would greatly improve patient outcomes through earlier detection of relapse or treatment resistance. However, MRD monitoring in solid tumors such as melanoma and BC are not well established. Here, we discuss the clinical applications of MRD monitoring in melanoma and BC patients and highlight the current approaches for detecting MRD in these solid tumors.

Diagnostic pathology of early systemic cancer: ERBB2 gene amplification in single disseminated cancer cells determines patient survival in operable esophageal cancer

Early metastatic dissemination and evolution of disseminated cancer cells (DCCs) outside the primary tumor is one reason for the failure of adjuvant therapies because it generates molecular genotypes and phenotypes different from primary tumors, which still underlie therapy decisions. Since ERBB2 amplification in esophageal DCCs but not in primary tumor cells predict outcome, we aimed to establish an assay with diagnostic reliability for single DCCs or circulating tumor cells. For this, we evaluated copy number alterations of more than 600 single DCCs from multiple cancer types to define reference regions suitable for quantification of target regions, such as ERBB2. We then compared ERBB2 quantitative PCR (qPCR) measurements with fluorescent in situ hybridization (FISH) data of various breast cancer cell lines and identified the aberration-calling threshold. The method was applied to two independent cohorts of esophageal cancer patients from Hamburg (n = 59) and Düsseldorf (n = 53). We found a high correlation between the single cell qPCR assay and the standard FISH assay (R = 0.98) and significant associations between amplification and survival for both patient cohorts (Hamburg (HH), p = 0.033; Düsseldorf (D), p = 0.052; pooled HH + D, p = 0.002) when applied to DCCs of esophageal cancer patients. Detection of a single ERBB2-amplified DCC was the most important risk factor for death from esophageal cancer (relative risk = 4.22; 95% CI = 1.91-9.32; p < 0.001). In our study, we detected ERBB2-amplified cells in 7% of patients. These patients could benefit from anti-ERBB2 targeting therapies.

Immunohistochemical detection of lymph node-DTCs in patients with node-negative HNSCC

This study was performed to systematically assess the prevalence, topography and prognostic impact of disseminated tumor cells (DTCs) in lymph nodes (LN) of patients with primary, regional and distant metastasis-free head and neck squamous cell carcinoma (HNSCC) who underwent resection with elective neck dissection. From the routinely processed resection specimen, we could prospectively analyze a total of 1.137 exactly mapped LNs of 50 pN0-HNSCC patients, classified as tumor free by routine histopathology. Three immunohistochemistry (IHC) assays using antibodies directed against CK5/14, a broad spectrum of CKs (1-8, 10, 14-16 and 19), and CD44v6, respectively, were applied on 4.190 LN sections to detect DTCs. The IHC results were correlated with clinicopathologic parameters and clinical follow-up data. We detected seven micrometastases (MM) in five patients and 31 DTCs in 12 patients. Overall, 15 (30%) patients were positive for DTCs or MMs. Strikingly, the anatomical distribution of LN affected with DTCs was not random, but was dependent on the lateralization of the primary tumor and clustered significantly most proximal to the primary tumor. None of the investigated patients developed loco-regional lymphatic or distant metastasis during the mean follow-up period of 71 months. Our results reveal clinically occult tumor cell dissemination as an early and frequent event in HNSCC. Considering that higher rates of recurrences in therapeutic LN dissection concepts have been reported than in elective neck dissection strategies, our DTC-data support to perform elective neck dissections, since they appear to be effective in preventing loco-regional lymphatic recurrence from LN DTCs or MMs.

Capsular nevus versus metastatic malignant melanoma - a diagnostic dilemma

INTRODUCTION

A positive finding of metastatic melanoma in a sentinel lymph node is an ominous sign and a strong predictor of overall survival. In contrast, current data trends have shown that patients with benign nevus cells in the sentinel nodes do not require additional therapy since their prognosis has been shown to be similar to that of patients with negative lymph nodes. Distinguishing between benign capsular nevi and metastatic melanoma often proves to be diagnostically problematic.

CASE PRESENTATION

In this case report we present two cases of melanoma in which sentinel lymph node biopsies proved to be difficult in distinguishing metastatic melanocytes from capsular nevus cells. In both cases, further workup was necessary for accurate diagnoses.

DISCUSSION

A lack of standardized distinctions of benign nevus cell from melanoma pose a diagnostic pitfall. Assigning a diagnosis of malignant melanoma might seem like the safer approach to avoid a false negative, but the resultant treatment, including the possibility of additional surgical complications, may cause anxiety, discomfort, and financial instability for the patient. Current methods of distinguishing the two based solely on histology may be insufficient due to similar pathologic patterns.

CONCLUSION

To avoid misdiagnosing a patient and performing unnecessary therapy, it would be beneficial to get a second opinion by additional histopathologists at a high volume center. Additionally, immunohistochemical staining should be carefully employed due to some overlap in commonly used markers. Using tissue morphology in conjunction with immunohistochemical staining may be the best way to make the most accurate diagnosis.

Immunotherapy of melanoma: efficacy and mode of action

Forty years of research have brought about the development of antibodies that induce effective antitumor immune responses through sustained activation of the immune system. These "immune checkpoint inhibitors" are directed against immune inhibitory molecules, such as cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed death 1 (PD-1) or programmed death ligand 1 (PD-L1). Disruption of the PD-1/PD-L1 interaction improves the intermediate-term prognosis even in patients with advanced stage IV melanoma. One and a half years after treatment initiation, 30-60 % of these patients are still alive. While cancer immunotherapies usually do not eradicate metastases completely, they do cause a regression by 20-80 %. It is well established that the immune system is able to kill tumor cells, and this has also been demonstrated for immunotherapies. Preclinical data, however, has shown that anti-cancer immunity is not limited to killing cancer cells. Thus, through interferon gamma and tumor necrosis factor, the immune system is able to induce stable tumor growth arrest, referred to as senescence. Ensuring patient survival by long-term stabilization of metastatic growth will therefore become a central goal of antitumor immunotherapies. This therapeutic approach is effective in melanoma and non-small-cell lung cancer. Once immunotherapies also have an indication for common cancer types, drug prices will have to drop considerably in order to be able to keep them available to those dependent on such therapies.

Melanoma-Derived BRAF(V600E) Mutation in Peritumoral Stromal Cells: Implications for in Vivo Cell Fusion

Melanoma often recurs in patients after the removal of the primary tumor, suggesting the presence of recurrent tumor-initiating cells that are undetectable using standard diagnostic methods. As cell fusion has been implicated to facilitate the alteration of a cell's phenotype, we hypothesized that cells in the peritumoral stroma having a stromal phenotype that initiate recurrent tumors might originate from the fusion of tumor and stromal cells. Here, we show that in patients with BRAF(V600E) melanoma, melanoma antigen recognized by T-cells (MART1)-negative peritumoral stromal cells express BRAF(V600E) protein. To confirm the presence of the oncogene at the genetic level, peritumoral stromal cells were microdissected and screened for the presence of BRAF(V600E) with a mutation-specific polymerase chain reaction. Interestingly, cells carrying the BRAF(V600E) mutation were not only found among cells surrounding the primary tumor but were also present in the stroma of melanoma metastases as well as in a histologically tumor-free re-excision sample from a patient who subsequently developed a local recurrence. We did not detect any BRAF(V600E) mutation or protein in the peritumoral stroma of BRAF(WT) melanoma. Therefore, our results suggest that peritumoral stromal cells contain melanoma-derived oncogenic information, potentially as a result of cell fusion. These hybrid cells display the phenotype of stromal cells and are therefore undetectable using routine histological assessments. Our results highlight the importance of genetic analyses and the application of mutation-specific antibodies in the identification of potentially recurrent-tumor-initiating cells, which may help better predict patient survival and disease outcome.

What are the social and individual factors that are associated with undergoing male circumcision as an HIV prevention strategy? A mixed methods study in Malawi

BACKGROUND

There is compelling evidence that medical male circumcision (MMC) decreases transmission of HIV. Nevertheless, the uptake of MMC is generally very low. Understanding the characteristics of individuals who choose MMC could inform future strategies for scaling-up MMC. The main objective of this study was to explore the social and individual characteristics of men that are associated with the uptake of circumcision as an HIV prevention strategy.

METHODS

A mixed-methods study, comprising a cross-sectional survey and an exploratory qualitative study, was conducted in Malawi. A total number of 1644 men, of at least 18 years old, participated in this study. A multistage sampling approach was used in the survey while convenience sampling was adopted in the qualitative study. Descriptive statistics, bivariate analyses and multivariable logistic regression were performed to analyze the cross-sectional data and thematic content approach to analyze the qualitative data.

RESULTS

Individuals who chose MMC were more likely to be unemployed (AOR=1.65; 95% CI: 1.30-2.11), to be married (AOR=3.16; 95% CI: 2.21-4.52) and to have had exposure to MMC promotions (AOR=1.81; 95% CI: 1.41-2.33). They were also more likely to reside in rural areas (AOR=1.85; 95% CI: 1.44-2.38), to perceive themselves as more vulnerable to HIV (AOR=1.60; 95% CI: 1.19-2.15) and to be more knowledgeable about the benefits of MMC (AOR=1.51; 95% CI: 1.16-1.97).

CONCLUSIONS

The findings suggest that men who had certain social and individual characteristics (for example better knowledge of the benefits of MMC, greater perceived vulnerability to HIV, married and unemployed) were more likely to choose circumcision as a prevention strategy for HIV than those who lacked those characteristics. Strategies for increasing MMC take-up should recognize the current social/individual landscape of MMC uptake and ensure that deliberate efforts targeting marginalized categories of men are available.

Deterministic Whole-Genome Amplification of Single Cells

This chapter describes a single-cell whole genome amplification method (WGA) that has been originally published under the name "Single Cell Comparative Genomic Hybridization (SCOMP)" (Klein et al., Proc Natl Acad Sci U S A 96(8):4494-4499, 1999). The method has recently become available commercially under the name "Ampli1(™) WGA Kit." It is a PCR-based technique for whole genome amplification (WGA) allowing comprehensive and quite uniform amplification of DNA from low quantities of input DNA material, in particular single cells. The method is based on a ligation-mediated adaptor linker PCR approach. In contrast to other PCR-based WGA approaches, both the primer design and mechanism underlying the fragmentation of genome are nonrandom, enabling high priming efficiency and deterministic fragmentation of template DNA. This is particularly important for the design of (diagnostic) assays targeting specific loci. Here, we describe the WGA protocol for amplification of single-cell genomes designed to provide high-quality material in quantity sufficient for a number of locus-specific and genome-wide downstream assays [e.g., targeted Sanger sequencing, restriction fragment length polymorphism (RFLP), quantitative PCR (qPCR), and array comparative genomic hybridization (CGH)].

Molecular profiling of single circulating tumor cells with diagnostic intention

Several hundred clinical trials currently explore the role of circulating tumor cell (CTC) analysis for therapy decisions, but assays are lacking for comprehensive molecular characterization of CTCs with diagnostic precision. We therefore combined a workflow for enrichment and isolation of pure CTCs with a non-random whole genome amplification method for single cells and applied it to 510 single CTCs and 189 leukocytes of 66 CTC-positive breast cancer patients. We defined a genome integrity index (GII) to identify single cells suited for molecular characterization by different molecular assays, such as diagnostic profiling of point mutations, gene amplifications and whole genomes of single cells. The reliability of > 90% for successful molecular analysis of high-quality clinical samples selected by the GII enabled assessing the molecular heterogeneity of single CTCs of metastatic breast cancer patients. We readily identified genomic disparity of potentially high relevance between primary tumors and CTCs. Microheterogeneity analysis among individual CTCs uncovered pre-existing cells resistant to ERBB2-targeted therapies suggesting ongoing microevolution at late-stage disease whose exploration may provide essential information for personalized treatment decisions and shed light into mechanisms of acquired drug resistance.

Hypoxia-independent drivers of melanoma angiogenesis

Tumor angiogenesis is a process which is traditionally regarded as the tumor’s response to low nutrient supply occurring under hypoxic conditions. However, hypoxia is not a pre-requisite for angiogenesis. The fact that even single tumor cells or small tumor cell aggregates are capable of attracting blood vessels reveals the early metastatic capability of tumor cells. This review sheds light on the hypoxia-independent mechanisms of tumor angiogenesis in melanoma.

The peripheral clock regulates human pigmentation

Although the regulation of pigmentation is well characterized, it remains unclear whether cell-autonomous controls regulate the cyclic on-off switching of pigmentation in the hair follicle (HF). As human HFs and epidermal melanocytes express clock genes and proteins, and given that core clock genes (PER1, BMAL1) modulate human HF cycling, we investigated whether peripheral clock activity influences human HF pigmentation. We found that silencing BMAL1 or PER1 in human HFs increased HF melanin content. Furthermore, tyrosinase expression and activity, as well as TYRP1 and TYRP2 mRNA levels, gp100 protein expression, melanocyte dendricity, and the number gp100+ HF melanocytes, were all significantly increased in BMAL1 and/or PER1-silenced HFs. BMAL1 or PER1 silencing also increased epidermal melanin content, gp100 protein expression, and tyrosinase activity in human skin. These effects reflect direct modulation of melanocytes, as BMAL1 and/or PER1 silencing in isolated melanocytes increased tyrosinase activity and TYRP1/2 expression. Mechanistically, BMAL1 knockdown reduces PER1 transcription, and PER1 silencing induces phosphorylation of the master regulator of melanogenesis, microphthalmia-associated transcription factor, thus stimulating human melanogenesis and melanocyte activity in situ and in vitro. Therefore, the molecular clock operates as a cell-autonomous modulator of human pigmentation and may be targeted for future therapeutic strategies.

5-Hydroxymethylcytosine expression in metastatic melanoma versus nodal nevus in sentinel lymph node biopsies

Sentinel lymph node biopsies are conducted to stage patients with newly diagnosed melanomas that have histopathological attributes conferring defined levels of metastatic potential. Because benign nevic cells may also form 'deposits' in lymph nodes (nodal nevus), the pathological evaluation for metastatic melanoma within sentinel lymph nodes can be challenging. Twenty-eight sentinel lymph node biopsy cases containing either metastatic melanoma (N=18) or nodal nevi (N=10) were retrieved from the archives of the Brigham and Women's Hospital, Department of Pathology (2011-2014). In addition, two sentinel lymph node cases that were favored to represent metastatic disease but whose histopathological features were viewed as equivocal, with melanoma favored, were also included. Dual labeling for the melanocyte lineage marker, MART-1, and the epigenetic marker, 5-hydroxymethylcytosine, a functionally significant indicator that has been shown to distinguish benign nevi from melanoma, was performed on all cases using immunohistochemistry and/or direct immunofluorescence. All (18 of 18) metastatic melanoma cases showed complete loss of 5-hydroxymethylcytosine nuclear staining in MART-1-positive cells, and all (10 of 10) nodal nevus cases demonstrated 5-hydroxymethylcytosine nuclear staining in MART-1-positive cells. In addition, 5-hydroxymethylcytosine staining confirmed the favored diagnoses of metastatic melanoma in the two 'equivocal' cases. Thus, 5-hydroxymethylcytosine may be a useful adjunctive marker to distinguish between benign nodal nevi and metastatic melanoma during the evaluation of sentinel lymph node biopsies for metastatic melanoma.

Laser Microdissection of FFPE Tissue Areas and Subsequent Whole Genome Amplification by Ampli1™

Laser microdissection (LMD) and whole genome amplification (WGA) are valuable tools to isolate, purify, and genetically analyze cancer cells from tissue sections. In this chapter, we describe a workflow for microdissecting small regions of interest from cancer tissue, i.e. formalin-fixed paraffin-embedded (FFPE) and cryo-conserved specimens, and subsequent whole genome amplification by a deterministic WGA approach (Ampli1™ WGA).

Analysis of Copy-Number Alterations in Single Cells Using Microarray-Based Comparative Genomic Hybridization (aCGH)

In this unit, we describe a workflow that enables array comparative genomic hybridization (aCGH) of single cells. The unit first describes the isolation and preparation of single peripheral mononuclear cells from blood (PBMC) to prepare a suitable reference DNA for aCGH experiments. An alternative procedure is described for the preparation of single cells of GM14667 and GM05423 cell lines to use as reference DNA and for sex-mismatched control experiments. A guide is also provided for micromanipulation of single cells. Next, the unit describes whole-genome amplification using adapter-linker PCR (Ampli1 WGA Kit) and an alternative nonlinear WGA method (PicoPLEX WGA Kit) for single-cell amplification. A protocol is also included for reamplification of Ampli1 WGA products, which can be used for aCGH as well. Finally, the use of 4 × 180k oligonucleotide microarrays to perform aCGH with single-cell WGA products is described.