Established and Emerging Biomarkers in Cutaneous Malignant Melanoma

Health professional and patient views of a novel prognostic test for melanoma: A theoretically informed qualitative study

OBJECTIVES

Cutaneous melanoma rates are steadily increasing. Up to 20% of patients diagnosed with AJCC Stage I/II melanomas will develop metastatic disease. To date there are no consistently reliable means to accurately identify truly high versus low-risk patient subpopulations. There is hence an urgent need for more accurate prediction of prognosis to determine appropriate clinical management. Validation of a novel prognostic test based on the immunohistochemical expression of two protein biomarkers in the epidermal microenvironment of primary melanomas was undertaken; loss of these biomarkers had previously been shown to be associated with a higher risk of recurrence or metastasis. A parallel qualitative study exploring secondary care health professional and patient views of the test was undertaken and this paper reports the perceived barriers and enablers to its implementation into the melanoma care pathway.

METHODS

Qualitative methods were employed drawing upon the Theoretical Domains Framework (TDF) in the exploration and analysis. An inductive-deductive analysis was performed, with all data coded using a thematic then TDF framework.

FINDINGS

20 dermatologists, plastic surgeons, cancer nurse specialists, oncologists and histopathologists participated. Nine TDF domains were relevant to all health professional groups and the 'Skills' and 'Beliefs about Capabilities' domains were relevant only to histopathologists. 'Optimism' and 'Beliefs about consequences' were strong enablers particularly for clinicians. 'Environmental context and resources' (impact on pathology services) and 'Knowledge' (the need for robust evidence about the test reliability) were the main perceived barriers. 19 patients and one carer were interviewed. For the patients eight domains were relevant. ('Knowledge', 'Emotions', 'Beliefs about consequences', 'Social Role and identity', 'Behavioural regulation', 'Memory, attention and decision processes', 'Reinforcement' and 'Skills'). The consequences of the implementation of the test were reassurance about future risk, changes to the follow-up pathway on which there were mixed views, and the need to ensure they maintained self-surveillance (Beliefs about consequences). The test was acceptable to all patient interviewees but the resultant changes to management would need to be supported by mechanisms for fast-track back into the clinic, further information on self-surveillance and clear management plans at the time the result is conveyed (Behavioural regulation).

CONCLUSIONS

Health professionals and patients perceived positive consequences-for patients and for health services-of adopting the test. However, its implementation would require exploration of the resource implications for pathology services, psychological support for patients with a high-risk test result and mechanisms to reassure and support patients should the test lead to reduced frequency or duration of follow-up. Exploring implementation at an early stage with health professionals presented challenges related to the provision of specific details of the test and its validation.

Comparison of 2D and 3D cell culture models for cell growth, gene expression and drug resistance

In vitro drug screening is widely used in the development of new drugs, because they constitute a cost-effective approach to select compounds with more potential for therapy. They are also an attractive alternative to in vivo testing. However, most of these assays are done in two-dimensional culture models, where cells are grown on a polystyrene or glass flat surface. In order to develop in vitro models that would more closely resemble physiological conditions, three-dimensional models have been developed. Here, we introduce two novel fully synthetic scaffolds produced using the polymer polyhydroxybutyrate (PHB): a Solvent-Casting Particle-Leaching (SCPL) membrane; and an electrospun membrane, to be used for 3D cultures of B16 F10 murine melanoma cells and 4T1 murine breast cancer cells. A 2D cell culture system in regular tissue culture plates and a classical 3D model where cells are grown on a commercially available gel derived from Engelbreth-Holm Swarm (EHS) tumor were used for comparison with the synthetic scaffolds. Cells were also collected from in vivo tumors grown as grafts in syngeneic mice. Morphology, cell viability, response to chemotherapy and gene expression analysis were used to compare all systems. In the electrospun membrane model, cells were grown on nanometer-scale fibers and in the SCPL membrane, which provides a foam-like structure for cell growth, pore sizes varied. Cells grown on all 3D models were able to form aggregates and spheroids, allowing for increased cell-cell contact when compared with the 2D system. Cell morphology was also more similar between 3D systems and cells collected from the in vivo tumors. Cells grown in 3D models showed an increase in resistance to dacarbazine, and cisplatin. Gene expression analysis also revealed similarities among all 3D platforms. The similarities between the two synthetic systems to the classic EHS gel model highlight their potential application as cost effective substitutes in drug screening, in which fully synthetic models could represent a step towards higher reproducibility. We conclude PHB synthetic membranes offer a valuable alternative for 3D cultures.

Epidermal autophagy and beclin 1 regulator 1 and loricrin: a paradigm shift in the prognostication and stratification of the American Joint Committee on Cancer stage I melanomas

BACKGROUND

The updated American Joint Committee on Cancer (AJCC) staging criteria for melanoma remain unable to identify high-risk stage I tumour subsets.

OBJECTIVES

To determine the utility of epidermal autophagy and beclin 1 regulator 1 (AMBRA1)/loricrin (AMLo) expression as a prognostic biomarker for AJCC stage I cutaneous melanoma.

METHODS

Peritumoral AMBRA1 expression was evaluated in a retrospective discovery cohort of 76 AJCC stage I melanomas. AMLo expression was correlated with clinical outcomes up to 12 years in two independent powered, retrospective validation and qualification cohorts comprising 379 AJCC stage I melanomas.

RESULTS

Decreased AMBRA1 expression in the epidermis overlying primary melanomas in a discovery cohort of 76 AJCC stage I tumours was associated with a 7-year disease-free survival (DFS) rate of 81·5% vs. 100% survival with maintained AMBRA1 (P < 0·081). Following an immunohistochemistry protocol for semi-quantitative analysis of AMLo, analysis was undertaken in validation (n = 218) and qualification cohorts (n = 161) of AJCC stage I melanomas. Combined cohort analysis revealed a DFS rate of 98·3% in the AMLo low-risk group (n = 239) vs. 85·4% in the AMLo high-risk cohort (n = 140; P < 0·001). Subcohort multivariate analysis revealed that an AMLo hazard ratio (HR) of 4·04 [95% confidence interval (CI) 1·69-9·66; P = 0·002] is a stronger predictor of DFS than Breslow depth (HR 2·97, 95% CI 0·93-9·56; P = 0·068) in stage IB patients.

CONCLUSIONS

Loss of AMLo expression in the epidermis overlying primary AJCC stage I melanomas identifies high-risk tumour subsets independently of Breslow depth. What's already known about this topic? There is an unmet clinical need for biomarkers of early-stage melanoma. Autophagy and beclin 1 regulator 1 (AMBRA1) is a proautophagy regulatory protein with known roles in cell proliferation and differentiation, and is a known tumour suppressor. Loricrin is a marker of epidermal terminal differentiation. What does this study add? AMBRA1 has a functional role in keratinocyte/epidermal proliferation and differentiation. The combined decrease/loss of peritumoral AMBRA1 and loricrin is associated with a significantly increased risk of metastatic spread in American Joint Committee on Cancer (AJCC) stage I tumours vs. melanomas, in which peritumoral AMBRA1 and loricrin are maintained, independently of Breslow depth. What is the translational message? The integration of peritumoral epidermal AMBRA1/loricrin biomarker expression into melanoma care guidelines will facilitate more accurate, personalized risk stratification for patients with AJCC stage I melanomas, thereby facilitating stratification for appropriate follow-up and informing postdiagnostic investigations, including sentinel lymph node biopsy, ultimately resulting in improved disease outcomes and rationalization of healthcare costs.

Monitoring Melanoma Using Circulating Free DNA

Genetic material derived from tumours is constantly shed into the circulation of cancer patients both in the form of circulating free nucleic acids and within circulating cells or extracellular vesicles. Monitoring cancer-specific genomic alterations, particularly mutant allele frequencies, in circulating nucleic acids allows for a non-invasive liquid biopsy for detecting residual disease and response to therapy. The advent of molecular targeted treatments and immunotherapies with increasing effectiveness requires corresponding effective molecular biology methods for the detection of biomarkers such as circulating nucleic acid to monitor and ultimately personalise therapy. The use of polymerase chain reaction (PCR)-based methods, such as droplet digital PCR, allows for a very sensitive analysis of circulating tumour DNA, but typically only a limited number of gene mutations can be detected in parallel. In contrast, next-generation sequencing allows for parallel analysis of multiple mutations in many genes. The development of targeted next-generation sequencing cancer gene panels optimised for the detection of circulating free DNA now provides both the flexibility of multiple mutation analysis coupled with a sensitivity that approaches or even matches droplet digital PCR. In this review, we discuss the advantages and disadvantages of these current molecular technologies in conjunction with how this field is evolving in the context of melanoma diagnosis, prognosis, and monitoring of response to therapy.

Metabolomic identification of diagnostic serum-based biomarkers for advanced stage melanoma

INTRODUCTION

Melanoma is a highly aggressive malignancy and is currently one of the fastest growing cancers worldwide. While early stage (I and II) disease is highly curable with excellent prognosis, mortality rates rise dramatically after distant spread. We sought to identify differences in the metabolome of melanoma patients to further elucidate the pathophysiology of melanoma and identify potential biomarkers to aid in earlier detection of recurrence.

METHODS

Using ¹H NMR and DI-LC-MS/MS, we profiled serum samples from 26 patients with stage III (nodal metastasis) or stage IV (distant metastasis) melanoma and compared their biochemical profiles with 46 age- and gender-matched controls.

RESULTS

We accurately quantified 181 metabolites in serum using a combination of ¹H NMR and DI-LC-MS/MS. We observed significant separation between cases and controls in the PLS-DA scores plot (permutation test p-value = 0.002). Using the concentrations of PC-aa-C40:3, DL-carnitine, octanoyl-L-carnitine, ethanol, and methylmalonyl-L-carnitine we developed a diagnostic algorithm with an AUC (95% CI) = 0.822 (0.665-0.979) with sensitivity and specificity of 100 and 56%, respectively. Furthermore, we identified arginine, proline, tryptophan, glutamine, glutamate, glutathione and ornithine metabolism to be significantly perturbed due to disease (p < 0.05).

CONCLUSION

Targeted metabolomic analysis demonstrated significant differences in metabolic profiles of advanced stage (III and IV) melanoma patients as compared to controls. These differences may represent a potential avenue for the development of multi-marker serum-based assays for earlier detection of recurrences, allow for newer, more effective targeted therapy when tumor burden is less, and further elucidate the pathophysiologic changes that occur in melanoma.

FoxM1: Repurposing an oncogene as a biomarker

The past few decades have witnessed a tremendous progress in understanding the biology of cancer, which has led to more comprehensive approaches for global gene expression profiling and genome-wide analysis. This has helped to determine more sophisticated prognostic and predictive signature markers for the prompt diagnosis and precise screening of cancer patients. In the search for novel biomarkers, there has been increased interest in FoxM1, an extensively studied transcription factor that encompasses most of the hallmarks of malignancy. Considering the attractive potential of this multifarious oncogene, FoxM1 has emerged as an important molecule implicated in initiation, development and progression of cancer. Bolstered with the skill to maneuver the proliferation signals, FoxM1 bestows resistance to contemporary anti-cancer therapy as well. This review sheds light on the large body of literature that has accumulated in recent years that implies that FoxM1 neoplastic functions can be used as a novel predictive, prognostic and therapeutic marker for different cancers. This assessment also highlights the key features of FoxM1 that can be effectively harnessed to establish FoxM1 as a strong biomarker in diagnosis and treatment of cancer.