Biomarkers in melanoma: staging, prognosis and detection of early metastases

A practical nomogram and risk stratification system predicting the cancer-specific survival for patients aged >50 with advanced melanoma

Objective

To investigate risk factors for advanced melanoma over 50 years of age and to develop and validate a new line chart and classification system.

Methods

The SEER database was screened for patients diagnosed with advanced melanoma from 2010 to 2019 and Cox regression analysis was applied to select variables affecting patient prognosis. The area under curve (AUC), relative operating characteristic curve (ROC), Consistency index (C-index), decision curve analysis (DCA), and survival calibration curves were used to verify the accuracy and utility of the model and to compare it with traditional AJCC tumor staging. The Kaplan-Meier curve was applied to compare the risk stratification between the model and traditional AJCC tumor staging.

Results

A total of 5166 patients were included in the study. Surgery, age, gender, tumor thickness, ulceration, the number of primary melanomas, M stage and N stage were the independent prognostic factors of CSS in patients with advanced melanoma (P<0.05). The predictive nomogram model was constructed and validated. The C-index values obtained from the training and validation cohorts were 0.732 (95%CI: 0.717-0.742) and 0.741 (95%CI: 0.732-0.751). Based on the observation and analysis results of the ROC curve, survival calibration curve, NRI, and IDI, the constructed prognosis model can accurately predict the prognosis of advanced melanoma and performs well in internal verification. The DCA curve verifies the practicability of the model. Compared with the traditional AJCC staging, the risk stratification in the model has a better identification ability for patients in different risk groups.

Conclusion

The nomogram of advanced melanoma and the new classification system were successfully established and verified, which can provide a practical tool for individualized clinical management of patients.

Gender-Dependent Specificities in Cutaneous Melanoma Predisposition, Risk Factors, Somatic Mutations, Prognostic and Predictive Factors: A Systematic Review

BACKGROUND AND AIM

Over the last decades, the incidence of melanoma has been steadily growing, with 4.2% of the population worldwide affected by cutaneous melanoma (CM) in 2020 and with a higher incidence and mortality in men than in women. We investigated both the risk factors for CM development and the prognostic and predictive factors for survival, stratifying for both sex and gender.

METHODS

We conducted a systematic review of studies indexed in PUB-MED, EMBASE, and Scopus until 4 February 2021. We included reviews, meta-analyses, and pooled analyses investigating differences between women and men in CM risk factors and in prognostic and predictive factors for CM survival.

DATA SYNTHESIS

Twenty-four studies were included, and relevant data extracted. Of these, 13 studies concerned potential risk factors, six concerned predictive factors, and five addressed prognostic factors of melanoma.

DISCUSSION

The systematic review revealed no significant differences in genetic predisposition to CM between males and females, while there appear to be several gender disparities regarding CM risk factors, partly attributable to different lifestyles and behavioral habits between men and women. There is currently no clear evidence of whether the mutational landscapes of CM differ by sex/gender. Prognosis is justified by a complex combination of phenotypes and immune functions, while reported differences between genders in predicting the effectiveness of new treatments are inconsistent. Overall, the results emerging from the literature reveal the importance of considering the sex/gender variable in all studies and pave the way for including it towards precision medicine.

CONCLUSIONS

Men and women differ genetically, biologically, and by social construct. Our systematic review shows that, although fundamental, the variable sex/gender is not among the ones collected and analyzed.

Lymphatic Mapping and Sentinel Lymph Node Biopsy in the Management of Primary Cutaneous Melanoma: Report of a Single-centre Experience

Aims and Background

Lymphatic mapping and sentinel lymph node biopsy provide important prognostic data in patients with early stage melanoma and are crucial in guiding the management of the tumor. We report our experience with lymphatic mapping and sentinel lymph node biopsy in a group of patients with primary cutaneous melanoma and discuss recent concepts and controversies on its use.

Patients and Methods

A total of 111 patients with stage I-II AJCC primary cutaneous melanoma underwent lymphatic mapping and sentinel lymph node biopsy from December 1999 through December 2004 using a standardized technique of preoperative lymphoscintigraphy and biopsy guided by blue dye injection in addition to a hand-held gamma probe. After removal, sentinel lymph nodes were submitted to serial sectioning and permanent preparations for histological and immunohistochemical examination. Complete lymph node dissection was performed only in patients with tumor-positive sentinel lymph nodes.

Results

Sentinel lymph nodes were identified and removed in all patients (detection rate of 100%), and metastases were found in 17 cases (15.3%). The incidence of metastasis in sentinel lymph nodes was 2.1%, 15.9%, 35.2%, and 41.6% for melanomas < or 1.0, 1.01-2.0, 2.01-4.0, and > 4.0 mm in thickness, respectively. Complete lymph node dissection was performed in 15 of 17 patients with positive sentinel lymph nodes, and metastases in non-sentinel lymph nodes were detected in only 2 cases (11.7%). Recurrences were more frequently observed in patients with a positive than in those with negative sentinel lymph node (41.1% vs 5.3% at a median follow-up of 31.5 months, P<0.001). The false-negative rate was 2.1%.

Conclusions

Our study confirms that lymphatic mapping and sentinel lymph node biopsy allow accurate staging and yield relevant prognostic information in patients with early stage melanoma.

PAX3d mRNA over 2.76 copies/µL in the bloodstream predicts cutaneous malignant melanoma relapse

OBJECTIVE

The aim of this study was to evaluate if our molecular algorithm, based on tumor circulating transcripts, may predict relapse risk in cutaneous malignant melanoma (CMM).

RESULTS

The multi-marker panel was able to differentiate patients with CMM from HC with high diagnostic sensitivity and specificity, especially for MITF-m and TGFB2 (91-100%) whose levels decreased during follow-up of recurrence-free patients, and remained stable in the case of relapse. PAX3d higher than 2.76 copies/µL emerged as a promising biomarker [specificity = 75-93% and negative predictive value = 75-98%] to stratify subjects at high risk of CMM recurrence independently of age, gender and AJCC staging [OD = 9.5(3.2-28.0), p < 0.001]. The survival analysis confirmed PAX3d performance in relapse prediction with significant differences in recurrence risk 12 months after the basal time-point (p = 0.008).

MATERIALS AND METHODS

Peripheral blood was collected from 111 CMM patients and from 87 healthy controls (HC) randomly selected. Each specimen was examined by qRT-PCR analysis for the expression of 3 tumor-related transcripts (PAX3d, MITF-m and TGFB2) at diagnosis, and at the following 6 and 12 months during clinical monitoring.

CONCLUSIONS

We demonstrated the usefulness of our molecular algorithm to indirectly detect circulating melanoma cells in blood, along with PAX3d capability to assess patients' progression and relapse prediction.

Loss of tumor suppressors KAI1 and p27 identifies a unique subgroup of primary melanoma patients with poor prognosis

Primary melanoma, a highly aggressive malignancy, exhibits heterogeneity in biologic behaviors, clinical characteristics, metastasis potential and mortality. The present study sought to identify the molecular signatures that define a subgroup of primary melanomas with high risks of metastasis and mortality. First, we identified the markers that best differentiated metastatic melanomas from primary melanomas by examining the expression of seven previously reported biomarkers (BRAF, Dicer, Fbw7, KAI1, MMP2, p27 and Tip60) in a training cohort consisting of 145 primary melanomas and 105 metastatic melanomas. KAI1 and p27, both tumor suppressors, emerged as best candidates. Loss of both tumor suppressors occurred in the majority (74.29%) of metastatic melanomas. Further, a subset (metastatic like, or "ML", 33.10%) of primary melanomas also lost these two tumor suppressors. Kaplan-Meier analysis indicated that ML subgroup of primary melanoma patients had much worse 5 year survival compared with other primary melanoma patients (P = 0.002). The result was confirmed in an independent validation cohort with 92 primary melanomas (P = 0.030) and in the combined cohort with 237 melanoma patients (P = 3.00E-4). Additionally, compared to KAI1 and p27 as an individual prognostic marker, the combined signature is more closely associated with melanoma patient survival (P = 0.025, 0.264 and 0.009, respectively). In conclusion, loss of both KAI1 and p27 defines a subgroup of primary melanoma patients with poor prognosis. This molecular signature may help in metastatic melanoma diagnosis and may provide information useful in identifying high-risk primary melanoma patients for more intensive clinical surveillance in the future.

Current concepts of metastasis in melanoma

The main cause of death in melanoma patients is widespread metastases. Staging of melanoma is based on the primary tumor thickness, ulceration, lymph node and distant metastases. Metastases develop in regional lymph nodes, as satellite or in-transit lesions, or in distant organs. Lymph flow and chemotaxis is responsible for the homing of melanoma cells to different sites. Standard pathologic evaluation of sentinel lymph nodes fails to find occult melanoma in a significant proportion of cases. Detection of small numbers of malignant melanoma cells in these and other sites, such as adjacent to the primary site, bone marrow or the systemic circulation, may be enhanced by immunohistochemistry, reverse transcription PCR, evaluation of lymphatic vessel invasion and proteomics. In the organs to which melanoma cells metastasize, extravasation of melanoma cells is regulated by adhesion molecules, matrix metalloproteases, chemokines and growth factors. Melanoma cells may travel along external vessel lattices. After settling in the metastatic sites, melanoma cells develop mechanisms that protect them against the attack of the immune system. It is thought that one of the reasons why melanoma cells are especially resistant to killing is the fact that melanocytes (cells from which melanoma cells derive) are resistant to such noxious factors as ultraviolet light and reactive oxygen species. Targeted melanoma therapies are, so far, largely unsuccessful, and new ones, such as adjuvant inhibition of melanogenesis, are under development.

Biomarkers in melanoma: Stage III and IV disease

The prognosis associated with Stage III melanoma is variable (17-65% 5-year survival) and primarily influenced by the number of lymph nodes involved, the presence of ulceration in a primary lesion, and the tumor burden present in each lymph node. In patients with metastatic (Stage IV) melanoma, the prognosis remains dismal (6-18% 5-year survival) and is influenced primarily by the sites (and extent) of metastatic involvement. Serum lactate dehydrogenase is the only prognostic biomarker useful in metastatic melanoma and it has been incorporated into the 2002 American Joint Committee on Cancer tumor, node, metastasis staging system. In this review, the known prognostic factors in Stage III and IV melanoma are reviewed. Selected investigational therapies and associated biomarkers are also discussed.

Evaluation of novel 99mTc(I)-labeled homobivalent α-melanocyte-stimulating hormone analogs for melanocortin-1 receptor targeting

Aiming to apply the multivalency concept to melanoma imaging, we have assessed the in vivo melanocortin type 1 receptor (MC1R)-targeting properties of (99m)Tc(I)-labeled homobivalent peptide conjugates which contain copies of the α-melanocyte-stimulating hormone (α-MSH) analog [Ac-Nle(4), Asp(5), D-Phe(7), Lys(11)]α-MSH4-11 separated by linkers of different length (L(2) nine atoms and L(3) 14 atoms). The MC1R-binding affinity of L(2) and L(3) is significantly higher than that of the monovalent conjugate L(1). Metallation of these conjugates yielded the complexes fac-[M(CO)(3)(k(3)-L)](+) (M is (99m)Tc/Re; 1/1a, L is L(1); 2/2a, L is L(2); 3/3a, L is L(3)), with IC(50) values in the subnanomolar and nanomolar range. The MC1R-mediated internalization of 2 and 3 is higher than that of 1 in B16F1 melanoma cells. Biodistribution studies in melanoma-bearing mice have shown low nonspecific accumulation with a tumor uptake that correlates with IC(50) values. However, no correlation between tumor uptake and valency was found. Nevertheless, 2 displayed the highest tumor retention, and the best tumor to nontarget organ ratios.

Melanoma update: diagnostic and prognostic factors that can effectively shape and personalize management

Routine light microscopy remains a powerful tool to diagnose, stage and prognose melanoma. Although it is very economical and efficient, it requires a significant level of expertise and, in difficult cases the final diagnosis is affected by subjective interpretation. Fortunately, new insights into the genomic aberrations characteristic of melanoma, coupled with ancillary studies, are further refining evaluation and management allowing for more confident diagnosis, more accurate staging and the selection of targeted therapy. In this article, we review the standard of care and new updates including four probe FISH, the 2009 American Joint Commission on Cancer staging of melanoma and mutant testing of melanoma, which will be crucial for targeted therapy of metastatic melanoma.

Melanoma targeting with alpha-melanocyte stimulating hormone analogs labeled with fac-[99mTc(CO)3]+: effect of cyclization on tumor-seeking properties

Early detection of primary melanoma tumors is essential because there is no effective treatment for metastatic melanoma. Several linear and cyclic radiolabeled alpha-melanocyte stimulating hormone (alpha-MSH) analogs have been proposed to target the melanocortin type 1 receptor (MC1R) overexpressed in melanoma. The compact structure of a rhenium-cyclized alpha-MSH analog (Re-CCMSH) significantly enhanced its in vivo tumor uptake and retention. Melanotan II (MT-II), a cyclic lactam analog of alpha-MSH (Ac-Nle-cyclo[Asp-His-DPhe-Arg-Trp-Lys]-NH2]), is a very potent and stable agonist peptide largely used in the characterization of melanocortin receptors. Taking advantage of the superior biological features associated with the MT-II cyclic peptide, we assessed the effect of lactam-based cyclization on the tumor-seeking properties of alpha-MSH analogs by comparing the pharmacokinetics profile of the 99mTc-labeled cyclic peptide betaAla-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 with that of the linear analog betaAla-Nle-Asp-His-DPhe-Arg-Trp-Lys-NH2 in melanoma-bearing mice. We have synthesized and coupled the linear and cyclic peptides to a bifunctional chelator containing a pyrazolyl-diamine backbone (pz) through the amino group of betaAla, and the resulting pz-peptide conjugates were reacted with the fac-[99mTc(CO)3]+ moiety. The 99mTc(CO)3-labeled conjugates were obtained in high yield, high specific activity, and high radiochemical purity. The cyclic 99mTc(CO)3-labeled conjugate presents a remarkable internalization (87.1% of receptor-bound tracer and 50.5% of total applied activity, after 6 h at 37 degrees C) and cellular retention (only 24.7% released from the cells after 5 h) in murine melanoma B16F1 cells. A significant tumor uptake and retention was obtained in melanoma-bearing C57BL6 mice for the cyclic radioconjugate [9.26 +/- 0.83 and 11.31 +/- 1.83% ID/g at 1 and 4 h after injection, respectively]. The linear 99mTc(CO)3-pz-peptide presented lower values for both cellular internalization and tumor uptake. Receptor blocking studies with the potent (Nle4,DPhe7)-alphaMSH agonist demonstrated the specificity of the radioconjugates to MC1R (74.8 and 44.5% reduction of tumor uptake at 4 h after injection for cyclic and linear radioconjugates, respectively).

A (99m)Tc(CO)(3)-labeled pyrazolyl-alpha-melanocyte-stimulating hormone analog conjugate for melanoma targeting

Melanoma primary tumors can be, in most cases, removed surgically, whereas there is no satisfactory treatment for metastatic melanoma, being almost always lethal at this stage. Therefore, early detection of primary melanoma tumors is essential. The finding that melanocortin-1 receptor (MC1R) is overexpressed in isolated melanoma cells and melanoma tissues led to the radiolabeling of several alpha-melanocyte-stimulating hormone (alpha-MSH) analogs for early detection and treatment of melanoma. We have coupled the alpha-MSH analog Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys-NH(2), through the epsilon-amino group of Lys(11), to a pyrazolyl-containing chelator (pz). The resulting pz-alpha-MSH analog reacted with the fac-[(99m)Tc(CO)(3)](+) moiety, giving [Ac-Nle(4),Asp(5),d-Phe(7),Lys(11)(pz-(99m)Tc(CO)(3))]alpha-MSH(4-11) in high yield, high specific activity and high radiochemical purity. This radioconjugate, which presents remarkable stability in vitro, exhibited time- and temperature-dependent internalization (4 h at 37 degrees C; 56.7% maximum internalization) and high cellular retention (only 38% was released from the cell after 5 h) in murine melanoma B16F1 cells. A significant tumor uptake [4.2+/-0.9%ID/g, at 4 h postinjection (p.i.)] was also obtained in melanoma-bearing C57BL6 mice. The in vivo affinity and specificity of the radioconjugate to MC1R were demonstrated by receptor-blocking studies with the potent NDP-MSH agonist (63.5% reduction in tumor uptake at 4 h p.i.).

Sequence variability of retroviral particles derived from human melanoma cells

We have shown that melanoma cells produce viral particles that contain sequences which are homologous to human endogenous retroviruses. In this study particles derived from different melanoma cell lines and from melanoma cells of a lymph node metastasis were characterized. We determined the density and the reverse transcriptase (RT) activity of viral particles. Furthermore, we analyzed the sequence variability of multiple clones of each particle preparation. The particles were found to package sequences, which vary for each of the analyzed cell lines. Moreover, even particles derived from the same cell line contain heterologous sequences.

Molecular diagnostics in melanoma

Molecular pathology is rapidly evolving, featuring continuous technologic improvements that offer novel clinical opportunities for the recognition of disease predisposition, for identifying sub-clinical disease, for more accurate diagnosis, for selecting efficacious and non-toxic therapy, and for monitoring of disease outcome. Currently, the identification and prognosis of primary cutaneous melanoma is based on histologic factors (tumor depth and ulceration) and clinical factors (number of lymph node and/or distant metastases). However, metastasis can occur in patients with thin melanomas, and sentinel lymph node biopsy does not identify all patients at risk for distant metastasis. New markers exist that correlate with melanoma progression, which may aid in melanoma identification, prognostication, and detection of minimal residual disease/early recurrence. Moreover, not many therapeutic options exist for melanoma as no regimen prolongs survival. Emerging data with investigational therapies suggest that certain markers might play a crucial role in identifying patients who will respond to therapy or show utility in the monitoring the response to therapy. Herein, molecular diagnostics that can potentially benefit the individual melanoma patient will be discussed.

Prognostic relevance of P-cadherin expression in melanocytic skin tumours analysed by high-throughput tissue microarrays

AIM

To investigate whether protein expression or cellular localisation of P-cadherin is associated with clinicopathological characteristics in benign and malignant melanocytic skin tumours.

EXPERIMENTAL DESIGN

P-cadherin expression and the Ki-67 labelling index were analysed immunohistochemically by using tissue microarrays (TMAs). Membranous and cytoplasmic expression was scored semiquantitatively (0 to 2+).

RESULTS

P-cadherin protein expression of any intensity (1+ to 2+) was detected in the membrane in 41.5% (132/318) and in the cytoplasm in 64.2% (204/318) of patients. In general, P-cadherin expression was significantly reduced in malignant melanomas (p<0.001) and melanoma metastases (p<0.001), compared with benign nevi. Additionally, loss of membranous P-cadherin was associated with Clark level (p = 0.011) and tumour thickness (p<0.001). Interestingly, a significantly lower P-cadherin expression was shown by dermal nevi than by compound and junctional nevi (p = 0.005; p = 0.025). In primary melanomas, a Ki-67 labelling index <5% was not associated with P-cadherin protein expression, suggesting that loss of P-cadherin expression was not associated with proliferation. None of the other clinical and histological factors analysed was significantly related to P-cadherin expression. Low cytoplasmic P-cadherin expression was associated with tumour recurrence (p = 0.03) in all the patients who were analysed. After testing various multivariate Cox regression models, loss of cytoplasmic P-cadherin expression remained a highly significant adverse risk factor for tumour recurrence in patients with tumours <2 mm.

CONCLUSIONS

Loss of cytoplasmic P-cadherin expression is common in advanced melanomas and can be a prognostic marker of progression in patients with melanoma, most useful in patients with primary tumours <2 mm in thickness.

Identification of a Melanoma Marker Derived from Melanoma-Associated Endogenous Retroviruses

We previously described the expression of melanoma-associated endogenous retrovirus (MERV) proteins and viral particles in human melanomas and metastases. The objective of the present study was to determine whether a humoral immune response to MERV proteins occurs in melanoma. Candidate B-cell epitopes on MERV proteins were predicted using bioinformatic screening. The reactivity of MERV peptides corresponding to the predicted epitopes with antibodies prevalent in sera of melanoma patients was analyzed. An immunodominant peptide located in the env protein of MERV was identified. Subsequent analyzes using 81 samples from stage I to stage IV melanoma patients and 95 sera from healthy subjects revealed statistically significant differences in seroprevalence of antibodies in melanoma sera samples when compared with reference samples from healthy subjects. The prevalence of anti-MERV antibodies in melanoma patient sera was confirmed by immunofluorescence on env-transfected cells. These data indicate the potential of this candidate peptide as target for diagnosis and immunotherapy.

Skp2 and p27kip1 expression in melanocytic nevi and melanoma: an inverse relationship

BACKGROUND

S-phase kinase associated protein-2 (Skp2) ubiquitin ligase p45(SKP2) is important in the degradation of p27kip1 (a cyclin dependent kinase inhibitor) and progression through the G1-S cell-cycle checkpoint. Low levels of p27 and high levels of Skp2 are related to poor prognosis in some cancers.

METHODS

Clinicopathologic features and immunohistochemical expression of Skp2 and p27kip1 were investigated in 198 melanocytic proliferations: 21 melanocytic nevi, 23 melanoma in situ, 119 primary melanoma, and 35 metastatic melanoma samples. Comparative and survival analyses were performed.

RESULTS

Progressive and significant increases and decreases in the nuclear expression of Skp2 and p27kip1, respectively, was identified moving from melanocytic nevi (0.05 +/- 0.2/85 +/- 15) to melanoma in situ (3 +/- 2/45 +/- 20) to primary cutaneous melanoma (12 +/- 9/30 +/- 25) to metastatic melanoma (25 +/- 15/15 +/- 20) (p < or = 0.006). Expression of these proteins also significantly correlated with increasing American Joint Committee on Cancer (AJCC) T (tumor) classification and AJCC stage (p < or = 0.01). Moreover, the level of these two proteins exhibited a significant inverse relationship (r = -0.4, p = 0.0001). Skp2 cytoplasmic labeling index of >20% predicted worse 10-year overall survival (38% vs. 86%, p = 0.04) in primary melanoma. Neither p27 nor Skp2 nuclear expression impacted significantly on prognosis.

CONCLUSIONS

Gain of Skp2 and loss of p27kip1 protein expression are implicated in melanoma progression where the level of p27kip1 may be regulated by targeted proteolysis via Skp2. Cytoplasmic expression of Skp2 defines a subset of aggressive melanomas and could represent another pathway of deregulation of the cell cycle.