Abstract

Malignant melanoma is the most aggressive form of cutaneous malignancy. It accounts for more than 75% of cancer-related deaths among cutaneous malignancies. It accounts for <5>

Introduction

Malignant melanoma is the most aggressive form of cutaneous malignancy. It accounts for more than 75% of cancer-related deaths among cutaneous malignancies. It accounts for <5 href="https://www.thieme-connect.com/products/ejournals/html/10.4103/ijmpo.ijmpo_204_18#JR_1" xss=removed>1] Sometimes, it is very difficult to differentiate between benign nevi from malignant melanoma. Numerous biomarkers are used in malignant melanoma with varying clinical applications, including diagnostic purposes, prognosis, therapeutic purpose, and targeted therapy against melanoma. Surgical excision is the primary treatment for cutaneous malignancy in early stage of melanoma, but in advanced stage, targeted therapy and immunotherapy play a significant role.

Importance of Biomarkers in Melanoma

The incidence of melanoma is rising over the past few decades. It is one of the malignancies which showed increased incidence across the world. There are various causes for the increasing incidence of melanomas such as prolonged exposure of ultraviolet (UV) rays, increased awareness of melanoma, and early detection of the malignancy.[2] Now, recent evidence showed that there is a significant increase in the incidence of melanomas all over the world. In the United States, the estimated death due to melanoma was 9710 in 2014.[3] Melanomas are most common in young adult age group of 25–29 years.[4] The 5-year survival in early stage (98%) of melanoma is much higher than advanced or metastatic disease (15%).

The fall of 5-year survival in advanced or metastatic stage is due to the late diagnosis or early spread of the tumor. Earlier diagnosis in melanoma has a significant survival advantage compared to late diagnosis.[5] In significant proportion of patients progress to advanced disease, even though they are treated early. The progression to advanced disease can be halted with targeted therapy against molecular biomarkers.

Etiology of Melanoma

It can arise from a preexisting nevus or developed from melanocytes following UV radiation exposure or immunosuppression.[6] Malignant melanoma can be classified as cutaneous and noncutaneous malignant melanoma. The etiology of both cutaneous and noncutaneous malignant melanoma is different. Sunlight exposure with UV radiation is considered a cause for cutaneous malignant melanoma, but noncutaneous malignant melanomas such as anorectal melanoma and melanoma arising from choroid plexus cannot be explained with the above cause.

Classification of Melanoma

Melanoma can be classified based on the following parameters:[7]

1. Based on the type of melanoma

   1. Lentiginous malignant melanoma

   2. Superficial spreading melanoma

   3. Nodular melanoma.

   4. Acral lentiginous melanoma

2. Based on organ involvement

   1. Cutaneous melanoma

   2. Mucous melanoma

   3. Ocular melanoma.

Prognostic Factors in Melanoma

The following are considered important prognostic factors in melanoma, which includes depth of invasion, nodal metastasis, mitotic index, presence of ulceration, location of melanoma, type of melanoma and molecular markers of melanoma.[8]

Melanoma detected at a later stage or advanced stage has poor prognosis compared to early stage. In the above-mentioned prognostic factors, only few factors can be modified to improve better outcome to the patient. Molecular markers are one of the prognostic factors that can be intervened to improve prognosis. Molecular markers and their therapeutic target are one of the factors that can be modified for improved survival and outcome. Now, considerable research work is going on to identify molecular prognostic markers and targeted therapy against that prognostic factors.

Management of Melanoma

Locoregional management

Locoregional management of melanoma depends on the depth of involvement and lymph node involvement. TNM staging, clinical staging and pathological staging highlighted from [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6].[9]

| Figure 1  Mechanism of action of BRAF and MEK inhibitors

i.

Vemurafenib

Vemurafenib is approved for BRAF V600E mutation-positive metastatic melanoma.[37] Vemurafenib is maximum beneficial in patient with stage M1c melanoma with increased lactate dehydrogenase concentration. After administration of vemurafenib, most of the tumors showed rapid response and tumor burden decreased in due course. It blocks both forms of BRAF mutation such as v600E (glutamine for valine) and V600k (lysine for valine).

Even though vemurafenib showed rapid response on tumor burden, the effect never lasted longer due to the development of resistance. The development of resistance in vemurafenib is due to either MAPK pathway dependent or MAPK pathway independent.[38] BRAF mutation is more common in patients with cutaneous melanoma compared with other types of melanoma such as ocular and mucous melanoma. Tumor with less number of BRAF mutation rarely responds to BRAF inhibitors.

How to overcome the resistance?

To overcome the resistance to vemurafenib, we can use two methods. First, we can use a combination of BRAF inhibitors along with MEK inhibitors.[39] Another method is intermittent use of vemurafenib.

Advantage of vemurafenib

Both vemurafenib and dabrafenib showed a significant impact on the treatment of metastatic melanoma to the brain. Both agents showed a significant improvement in BRAF-mutant melanoma with brain metastases than whole-brain irradiation for melanoma.

ii.

Dabrafenib

Dabrafenib is another BRAF inhibitor. The response rate to dabrafenib depends on the type of BRAF mutation. The response rate to BRAF V600E is approximately around 60% whereas BRAF V600K showed a response rate of around 13%. Hence, it is mandatory to check the type of BRAF mutation before giving dabrafenib as a targeted therapy. Like vemurafenib, dabrafenib also showed a significant improvement in response rate and progression-free survival in BRAF-mutant metastatic melanoma compared to conventional chemotherapy.[40]

iii.

Sorafenib

Sorafenib is also a kinase inhibitor that acts on inhibiting kinase at multiple targets. It acts by inhibiting VEGF receptors VEGFR1, VEGFR2, and VEGFR3 and the platelet-derived growth factor receptor PDGFR. It also acts by inhibiting FLT3, C-Kit, and BRAF. There are many studies conducted to detect the use of sorafenib in melanoma. The results of most of the studies showed sorafenib as a monotherapy or combined chemotherapy of limited use. According to the study, only few subpopulations showed benefit in response to sorafenib.

Adverse effects of BRAF inhibitors

The safety profile and side effect profile of both vemurafenib and dabrafenib are same. However, the incidence of photosensitivity is much higher in vemurafenib and pyrexia is more in dabrafenib. There are increased incidence of squamous cell carcinoma following administration of vemurafenib, particularly keratoacanthoma. The reason for the development of squamous cell carcinoma is due to paradoxical activation of the MAPK pathway in nonmutant BRAF (wild-type BRAF).[41] Otherwise, both the drugs are safe for the administration of advanced or metastatic BRAF-mutant melanoma.

b.

Mek Inhibitors

iv.

Trametinib

Trametinib is also a targeted therapy similar to vemurafenib and dabrafenib. It acts by inhibiting MEK which is the only known substrate of BRAF, which, in turn, leads to decreased cell signal and growth of malignant cells [Figure 1]. It is useful in both BRAF V600E/K-mutant and unresectable metastatic melanoma.[42] The net effect of trametinib persists in patients who are already given chemotherapy or immunotherapy, but this effect is lost in patients who have already undergone BRAF inhibitor therapy. Hence, the selection of patients as well as screening of patients with mutation is very important before initiating trametinib therapy.[43]

v.

Selumetinib

Selumetinib is an MEK inhibitor which is also involved in MAPK pathway. A Phase III trial using selumetinib as a monotherapy or combined with chemotherapy fails to improve disease-free survival or progression-free survival in patients with melanoma. As per the current recommendations, selumetinib is not recommended for advanced or metastatic melanoma.

Adverse effect of MEK inhibitors

MEK inhibitors are well tolerated compared with BRAF inhibitors. Most of the side effects of MEK inhibitors belong to cutaneous side effects such as rash and gastrointestinal side effects such as diarrhea and gastrointestinal upset.

Major limitations of BRAF inhibitors

Kinase inhibitors targeting RAS/RAF/MEK pathway are useful in only 40%–50% of patients with malignant melanoma, because BRAF mutation is detected only in 40%–50% of patients with melanoma.[44]

Mechanism of Combination Targeted Therapy

Up regulation of melanoma antigen

After administration of BRAF inhibitors, most of the melanoma cells express melanoma antigens such as MART-1, gp100, c-kit, and class I MHC antigen. MEK inhibitors also increase melanoma antigen expression in both BRAF-mutant and BRAF nonmutant melanoma.

Increased tumor-infiltrating lymphocyte function

After administration of BRAF inhibitors, there is an increased expression of tumor-infiltrating lymphocyte in tumor specimen. Patients who develop resistance or disease progression following BRAF inhibitors showed decreased TILs, which was restored following combination therapy with BRAF and MEK inhibitors.[45]

Block immune suppression

Evasion of immune system occurs following secretion of oncogenic protein by BRAF-mutant cells. BRAF inhibitors decrease these immune suppression agents, thereby increasing T cell infiltration.

Combined targeted therapy

The combination of BRAF and MEK inhibitors showed a significant improvement in progression-free survival and overall survival.[45] Another advantage of combined therapy is delay in the onset of BRAF resistance and decreased toxicity including lower incidence of squamous cell carcinoma due to blocking of paradoxical MAPK activation.[46]

CRLA-4 inhibitors

Ipilimumab is an antibody against cytotoxic T-lymphocyte antigen-4 (CTLA-4) approved for unresectable metastatic melanoma [Table 8]. The main function of CTLA-4 is that it downregulates T cell against immune response against self-antigen and prevents autoimmunity. Ipilimumab helps in melanoma by blocking CTLA-4, thereby activating T cell against tumor antigen cell [Figure 2].[47]

| Figure 2  Mechanism of action of CTLA-4 inhibitors

Advantage of ipilimumab

The action of ipilimumab depends on the CTLA-4 expression, rather than genetic mutation or expression of cells. Hence, it is effective in all tumors in a patient. The overall survival of this drug does not depends on age or sex of the patient, serum LDH level, stage of the disease, and previous chemotherapy.

The effect of ipilimumab persists even after cessation treatment. Retreatment after disease progression may reactivate the immune system, which was already primed by ipilimumab. Ipilimumab is administered at the rate of 3 mg/kg irrespective of the type of melanoma. Like BRAF inhibitors, ipilimumab also penetrates the blood–brain barrier and mounts an immune response against metastases.

Adverse effects of ipilimumab

Ipilimumab is the drug that mainly acts on the tumor based on the immune expression, so it is obvious that after administration of ipilimumab, immune reactions are expected. Most of the immune reactions affect the gastrointestinal tract, central nervous system, cutaneous lesions, and endocrine systems. Most of the adverse events following ipilimumab can be cured with oral or parenteral steroids for a period of 6–8 weeks.

Combination therapy

The combination therapy with ipilimumab and vemurafenib has showed a significant increase in hepatic injury and hepatotoxicity. This hepatotoxicity is due to increased paradoxical activity of MAPK pathway in liver cells with wild-type BRAF following BRAF inhibitors.

d.

Anti-PD-1 antibodies and Anti-PD-L1 antibodies

Immune system has constant surveillance on foreign bodies as well as tumor cells. However, the tumor cells have their own pathway or mechanism for evading immune system. Immune regulatory mechanism is one of the targeted therapies for melanoma. The programmed death 1 is an inhibitory T cell receptor, which has an effect on tumor cell through its ligand called programmed death ligand 1. Programmed cell death 1 (PD-1) is 288 amino acid-containing receptor [Figure 3].[48]

| Figure 3  MechMechanism of action of PD-1 and PD-L1 inhibitors

Blockage of PD-1 or programmed death-ligand 1 (PD-L1) with antibodies has a significant effect tumor control because it specifically acts on tumor-specific antigen. Because of its specific effect on T cell, PD-1 and PD-L1 antibodies have a significantly higher effect on tumor cell with lesser side effects.[49]

PD-1 downregulates T cells by sending inhibitory signals to its ligand PD-L1. Programmed death receptor 1 is expressed in variety of tissues including normal cells and numerous cancerous cells. The mechanism of PD-1 action depends on the inhibitory action on the T cells, thereby preventing T cell acts on the tumor cell. PD-1 plays an important role in immunity against chronic infection and tumor antigen.

Mechanism of action of anti-programmed cell death 1 and anti-programmed death-ligand 1

The tumor cells located in our body have to develop some mechanism to evade from our immune system. One of the most important evading systems is called adaptive immune resistance where tumor tries to express PD-L1 to protect tumor cells against cytotoxic T cell destruction.

Anti-PD-1 antibodies have higher tumor activity and lesser side effect compared with CTLA-4 inhibitors [Table 9] and [Table 10]. The antitumor response by anti-PD-1 depends on multiple factors, but most of the studies showed long-lasting antitumor effects. All anti-PD-1 antibodies developed from IgG4 humanized antibody.

1.  Bertolotto C. Melanoma: From melanocyte to genetic alterations and clinical options. Scientifica (Cairo) 2013; 2013: 635203
2.  Watts JM, Kishtagari A, Hsu M, Lacouture ME, Postow MA, Park JH. et al. Melanoma and non-melanoma skin cancers in hairy cell leukaemia: A surveillance, epidemiology and end results population analysis and the 30-year experience at memorial Sloan kettering cancer center. Br J Haematol 2015; 171: 84-90
3.  Landers TF, Ferng YH, McLoughlin JW, Barrett AE, Larson E. Antibiotic identification, use, and self-medication for respiratory illnesses among urban Latinos. J Am Acad Nurse Pract 2010; 22: 488-95
4.  Puig S, Marcoval J, Paradelo C, Azon A, Bartralot R, Bel S. et al. Melanoma incidence increases in the elderly of Catalonia but not in the younger population: Effect of prevention or consequence of immigration?. Acta Derm Venereol 2015; 95: 422-6
5.  Garnett E, Townsend J, Steele B, Watson M. Characteristics, rates, and trends of melanoma incidence among Hispanics in the USA. Cancer Causes Control 2016; 27: 647-59
6.  Rastrelli M, Alaibac M, Stramare R, Chiarion Sileni V, Montesco MC, Vecchiato A. et al. Melanoma m (zero): Diagnosis and therapy. ISRN Dermatol 2013; 2013: 616170
7.  Scolyer RA, Long GV, Thompson JF. Evolving concepts in melanoma classification and their relevance to multidisciplinary melanoma patient care. Mol Oncol 2011; 5: 124-36
8.  Vogelsang M, Wilson M, Kirchhoff T. Germline determinants of clinical outcome of cutaneous melanoma. Pigment Cell Melanoma Res 2016; 29: 15-26
9.  Ascierto PA, Grimaldi AM, Anderson AC, Bifulco C, Cochran A, Garbe C. et al. Future perspectives in melanoma research: Meeting report from the “Melanoma Bridge”, Napoli, December 5th–8th 2013. J Transl Med 2014; 12: 277
10.  Han D, Thomas DC, Zager JS, Pockaj B, White RL, Leong SP. Clinical utilities and biological characteristics of melanoma sentinel lymph nodes. World J Clin Oncol 2016; 7: 174-88
11.  Luke JJ, Schwartz GK. Chemotherapy in the management of advanced cutaneous malignant melanoma. Clin Dermatol 2013; 31: 290-7
12.  Mayeux R. Biomarkers: Potential uses and limitations. NeuroRx 2004; 1: 182-8
13.  Strimbu K, Tavel JA. What are biomarkers?. Curr Opin HIV AIDS 2010; 5: 463-6
14.  Watt B, van Niel G, Raposo G, Marks MS. PMEL: A pigment cell-specific model for functional amyloid formation. Pigment Cell Melanoma Res 2013; 26: 300-15
15.  Weinstein D, Leininger J, Hamby C, Safai B. Diagnostic and prognostic biomarkers in melanoma. J Clin Aesthet Dermatol 2014; 7: 13-24
16.  Ebstein F, Keller M, Paschen A, Walden P, Seeger M, Bürger E. et al. Exposure to melan-A/MART-126-35 tumor epitope specific CD8(+)T cells reveals immune escape by affecting the ubiquitin-proteasome system (UPS). Sci Rep 2016; 6: 25208
17.  Choi J, Jee JG. Repositioning of thiourea-containing drugs as tyrosinase inhibitors. Int J Mol Sci 2015; 16: 28534-48
18.  Wellbrock C, Arozarena I. Microphthalmia-associated transcription factor in melanoma development and MAP-kinase pathway targeted therapy. Pigment Cell Melanoma Res 2015; 28: 390-406
19.  Dadras SS, Lin RJ, Razavi G, Kawakami A, Du J, Feige E. et al. Anovel role for microphthalmia-associated transcription factor-regulated pigment epithelium-derived factor during melanoma progression. Am J Pathol 2015; 185: 252-65
20.  Bresnick AR, Weber DJ, Zimmer DB. S100 proteins in cancer. Nat Rev Cancer 2015; 15: 96-109
21.  Chen H, Xu C, Jin Q, Liu Z. S100 protein family in human cancer. Am J Cancer Res 2014; 4: 89-115
22.  Trefzer U, Chen Y, Herberth G, Hofmann MA, Kiecker F, Guo Y. et al. The monoclonal antibody SM5-1 recognizes a fibronectin variant which is widely expressed in melanoma. BMC Cancer 2006; 6: 8
23.  Rolih V, Barutello G, Iussich S, De Maria R, Quaglino E, Buracco P. et al. CSPG4: A prototype oncoantigen for translational immunotherapy studies. J Transl Med 2017; 15: 151
24.  Hale CS, Qian M, Ma MW, Scanlon P, Berman RS, Shapiro RL. et al. Mitotic rate in melanoma: Prognostic value of immunostaining and computer-assisted image analysis. Am J Surg Pathol 2013; 37: 882-9
25.  Ladstein RG, Bachmann IM, Straume O, Akslen LA. Ki-67 expression is superior to mitotic count and novel proliferation markers PHH3, MCM4 and mitosin as a prognostic factor in thick cutaneous melanoma. BMC Cancer 2010; 10: 140
26.  Rapanotti MC, Campione E, Spallone G, Orlandi A, Bernardini S, Bianchi L. Minimal residual disease in melanoma: Circulating melanoma cells and predictive role of MCAM/MUC18/MelCAM/CD146. Cell Death Discov 2017; 3: 17005
27.  Gumulec J, Raudenska M, Adam V, Kizek R, Masarik M. Metallothionein-immunohistochemical cancer biomarker: A meta-analysis. PLoS One 2014; 9: e85346
28.  Ho J, de Moura MB, Lin Y, Vincent G, Thorne S, Duncan LM. et al. Importance of glycolysis and oxidative phosphorylation in advanced melanoma. Mol Cancer 2012; 11: 76
29.  Chaube B, Malvi P, Singh SV, Mohammad N, Meena AS, Bhat MK. Targeting metabolic flexibility by simultaneously inhibiting respiratory complex I and lactate generation retards melanoma progression. Oncotarget 2015; 6: 37281-99
30.  Fang S, Wang Y, Sui D, Liu H, Ross MI, Gershenwald JE. et al. C-reactive protein as a marker of melanoma progression. J Clin Oncol 2015; 33: 1389-96
31.  Meral R, Duranyildiz D, Tas F, Camlica H, Yasasever V, Kurul S. et al. Prognostic significance of melanoma inhibiting activity levels in malignant melanoma. Melanoma Res 2001; 11: 627-32
32.  Rajabi P, Neshat A, Mokhtari M, Rajabi MA, Eftekhari M, Tavakoli P. The role of VEGF in melanoma progression. J Res Med Sci 2012; 17: 534-9
33.  Russo A, Caltabiano R, Longo A, Avitabile T, Franco LM, Bonfiglio V. et al. Increased levels of miRNA-146a in serum and histologic samples of patients with uveal melanoma. Front Pharmacol 2016; 7: 424
34.  Kumar S, Sharma P, Kumar D, Chakraborty G, Gorain M, Kundu GC. Functional characterization of stromal osteopontin in melanoma progression and metastasis. PLoS One 2013; 8: e69116
35.  Kee D, McArthur G. Targeted therapies for cutaneous melanoma. Hematol Oncol Clin North Am 2014; 28: 491-505
36.  Evans MS, Madhunapantula SV, Robertson GP, Drabick JJ. Current and future trials of targeted therapies in cutaneous melanoma. Adv Exp Med Biol 2013; 779: 223-55
37.  Wong DJ, Ribas A. Targeted therapy for melanoma. Cancer Treat Res 2016; 167: 251-62
38.  Grimaldi AM, Simeone E, Festino L, Vanella V, Palla M, Ascierto PA. Novel mechanisms and therapeutic approaches in melanoma: Targeting the MAPK pathway. Discov Med 2015; 19: 455-61
39.  Hu-Lieskovan S, Mok S, Homet Moreno B, Tsoi J, Robert L, Goedert L. et al. Improved antitumor activity of immunotherapy with BRAF and MEK inhibitors in BRAF (V600E) melanoma. Sci Transl Med 2015; 7: 279ra41
40.  Flaherty KT, Infante JR, Daud A, Gonzalez R, Kefford RF, Sosman J. et al. Combined BRAF and MEK inhibition in melanoma with BRAF V600 mutations. N Engl J Med 2012; 367: 1694-703
41.  Long GV, Stroyakovskiy D, Gogas H, Levchenko E, de Braud F, Larkin J. et al. Combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma. N Engl J Med 2014; 371: 1877-88
42.  Sullivan R, LoRusso P, Boerner S, Dummer R. Achievements and challenges of molecular targeted therapy in melanoma. Am Soc Clin Oncol Educ Book 2015; 35: 177-86
43.  Johnson DB, Flaherty KT, Weber JS, Infante JR, Kim KB, Kefford RF. et al. Combined BRAF (Dabrafenib) and MEK inhibition (Trametinib) in patients with BRAFV600-mutant melanoma experiencing progression with single-agent BRAF inhibitor. J Clin Oncol 2014; 32: 3697-704
44.  Wagle N, Van Allen EM, Treacy DJ, Frederick DT, Cooper ZA, Taylor-Weiner A. et al. MAP kinase pathway alterations in BRAF-mutant melanoma patients with acquired resistance to combined RAF/MEK inhibition. Cancer Discov 2014; 4: 61-8
45.  Queirolo P, Picasso V, Spagnolo F. Combined BRAF and MEK inhibition for the treatment of BRAF-mutated metastatic melanoma. Cancer Treat Rev 2015; 41: 519-26
46.  Menzies AM, Long GV. Dabrafenib and trametinib, alone and in combination for BRAF-mutant metastatic melanoma. Clin Cancer Res 2014; 20: 2035-43
47.  Camacho LH. CTLA-4 blockade with ipilimumab: Biology, safety, efficacy, and future considerations. Cancer Med 2015; 4: 661-72
48.  Mahoney KM, Freeman GJ, McDermott DF. The next immune-checkpoint inhibitors: PD-1/PD-L1 blockade in melanoma. Clin Ther 2015; 37: 764-82
49.  Tsai KK, Daud AI. The role of anti-PD-1/PD-L1 agents in melanoma: Progress to date. Drugs 2015; 75: 563-75
50.  Ott PA, Hodi FS, Robert C. CTLA-4 and PD-1/PD-L1 blockade: New immunotherapeutic modalities with durable clinical benefit in melanoma patients. Clin Cancer Res 2013; 19: 5300-9
51.  Das R, Verma R, Sznol M, Boddupalli CS, Gettinger SN, Kluger H. et al. Combination therapy with anti-CTLA-4 and anti-PD-1 leads to distinct immunologic changes in vivo. J Immunol 2015; 194: 950-9

| Figure 1  Mechanism of action of BRAF and MEK inhibitors

| Figure 2  Mechanism of action of CTLA-4 inhibitors

| Figure 3  MechMechanism of action of PD-1 and PD-L1 inhibitors

1.  Bertolotto C. Melanoma: From melanocyte to genetic alterations and clinical options. Scientifica (Cairo) 2013; 2013: 635203
2.  Watts JM, Kishtagari A, Hsu M, Lacouture ME, Postow MA, Park JH. et al. Melanoma and non-melanoma skin cancers in hairy cell leukaemia: A surveillance, epidemiology and end results population analysis and the 30-year experience at memorial Sloan kettering cancer center. Br J Haematol 2015; 171: 84-90
3.  Landers TF, Ferng YH, McLoughlin JW, Barrett AE, Larson E. Antibiotic identification, use, and self-medication for respiratory illnesses among urban Latinos. J Am Acad Nurse Pract 2010; 22: 488-95
4.  Puig S, Marcoval J, Paradelo C, Azon A, Bartralot R, Bel S. et al. Melanoma incidence increases in the elderly of Catalonia but not in the younger population: Effect of prevention or consequence of immigration?. Acta Derm Venereol 2015; 95: 422-6
5.  Garnett E, Townsend J, Steele B, Watson M. Characteristics, rates, and trends of melanoma incidence among Hispanics in the USA. Cancer Causes Control 2016; 27: 647-59
6.  Rastrelli M, Alaibac M, Stramare R, Chiarion Sileni V, Montesco MC, Vecchiato A. et al. Melanoma m (zero): Diagnosis and therapy. ISRN Dermatol 2013; 2013: 616170
7.  Scolyer RA, Long GV, Thompson JF. Evolving concepts in melanoma classification and their relevance to multidisciplinary melanoma patient care. Mol Oncol 2011; 5: 124-36
8.  Vogelsang M, Wilson M, Kirchhoff T. Germline determinants of clinical outcome of cutaneous melanoma. Pigment Cell Melanoma Res 2016; 29: 15-26
9.  Ascierto PA, Grimaldi AM, Anderson AC, Bifulco C, Cochran A, Garbe C. et al. Future perspectives in melanoma research: Meeting report from the “Melanoma Bridge”, Napoli, December 5th–8th 2013. J Transl Med 2014; 12: 277
10.  Han D, Thomas DC, Zager JS, Pockaj B, White RL, Leong SP. Clinical utilities and biological characteristics of melanoma sentinel lymph nodes. World J Clin Oncol 2016; 7: 174-88
11.  Luke JJ, Schwartz GK. Chemotherapy in the management of advanced cutaneous malignant melanoma. Clin Dermatol 2013; 31: 290-7
12.  Mayeux R. Biomarkers: Potential uses and limitations. NeuroRx 2004; 1: 182-8
13.  Strimbu K, Tavel JA. What are biomarkers?. Curr Opin HIV AIDS 2010; 5: 463-6
14.  Watt B, van Niel G, Raposo G, Marks MS. PMEL: A pigment cell-specific model for functional amyloid formation. Pigment Cell Melanoma Res 2013; 26: 300-15
15.  Weinstein D, Leininger J, Hamby C, Safai B. Diagnostic and prognostic biomarkers in melanoma. J Clin Aesthet Dermatol 2014; 7: 13-24
16.  Ebstein F, Keller M, Paschen A, Walden P, Seeger M, Bürger E. et al. Exposure to melan-A/MART-126-35 tumor epitope specific CD8(+)T cells reveals immune escape by affecting the ubiquitin-proteasome system (UPS). Sci Rep 2016; 6: 25208
17.  Choi J, Jee JG. Repositioning of thiourea-containing drugs as tyrosinase inhibitors. Int J Mol Sci 2015; 16: 28534-48
18.  Wellbrock C, Arozarena I. Microphthalmia-associated transcription factor in melanoma development and MAP-kinase pathway targeted therapy. Pigment Cell Melanoma Res 2015; 28: 390-406
19.  Dadras SS, Lin RJ, Razavi G, Kawakami A, Du J, Feige E. et al. Anovel role for microphthalmia-associated transcription factor-regulated pigment epithelium-derived factor during melanoma progression. Am J Pathol 2015; 185: 252-65
20.  Bresnick AR, Weber DJ, Zimmer DB. S100 proteins in cancer. Nat Rev Cancer 2015; 15: 96-109
21.  Chen H, Xu C, Jin Q, Liu Z. S100 protein family in human cancer. Am J Cancer Res 2014; 4: 89-115
22.  Trefzer U, Chen Y, Herberth G, Hofmann MA, Kiecker F, Guo Y. et al. The monoclonal antibody SM5-1 recognizes a fibronectin variant which is widely expressed in melanoma. BMC Cancer 2006; 6: 8
23.  Rolih V, Barutello G, Iussich S, De Maria R, Quaglino E, Buracco P. et al. CSPG4: A prototype oncoantigen for translational immunotherapy studies. J Transl Med 2017; 15: 151
24.  Hale CS, Qian M, Ma MW, Scanlon P, Berman RS, Shapiro RL. et al. Mitotic rate in melanoma: Prognostic value of immunostaining and computer-assisted image analysis. Am J Surg Pathol 2013; 37: 882-9
25.  Ladstein RG, Bachmann IM, Straume O, Akslen LA. Ki-67 expression is superior to mitotic count and novel proliferation markers PHH3, MCM4 and mitosin as a prognostic factor in thick cutaneous melanoma. BMC Cancer 2010; 10: 140
26.  Rapanotti MC, Campione E, Spallone G, Orlandi A, Bernardini S, Bianchi L. Minimal residual disease in melanoma: Circulating melanoma cells and predictive role of MCAM/MUC18/MelCAM/CD146. Cell Death Discov 2017; 3: 17005
27.  Gumulec J, Raudenska M, Adam V, Kizek R, Masarik M. Metallothionein-immunohistochemical cancer biomarker: A meta-analysis. PLoS One 2014; 9: e85346
28.  Ho J, de Moura MB, Lin Y, Vincent G, Thorne S, Duncan LM. et al. Importance of glycolysis and oxidative phosphorylation in advanced melanoma. Mol Cancer 2012; 11: 76
29.  Chaube B, Malvi P, Singh SV, Mohammad N, Meena AS, Bhat MK. Targeting metabolic flexibility by simultaneously inhibiting respiratory complex I and lactate generation retards melanoma progression. Oncotarget 2015; 6: 37281-99
30.  Fang S, Wang Y, Sui D, Liu H, Ross MI, Gershenwald JE. et al. C-reactive protein as a marker of melanoma progression. J Clin Oncol 2015; 33: 1389-96
31.  Meral R, Duranyildiz D, Tas F, Camlica H, Yasasever V, Kurul S. et al. Prognostic significance of melanoma inhibiting activity levels in malignant melanoma. Melanoma Res 2001; 11: 627-32
32.  Rajabi P, Neshat A, Mokhtari M, Rajabi MA, Eftekhari M, Tavakoli P. The role of VEGF in melanoma progression. J Res Med Sci 2012; 17: 534-9
33.  Russo A, Caltabiano R, Longo A, Avitabile T, Franco LM, Bonfiglio V. et al. Increased levels of miRNA-146a in serum and histologic samples of patients with uveal melanoma. Front Pharmacol 2016; 7: 424
34.  Kumar S, Sharma P, Kumar D, Chakraborty G, Gorain M, Kundu GC. Functional characterization of stromal osteopontin in melanoma progression and metastasis. PLoS One 2013; 8: e69116
35.  Kee D, McArthur G. Targeted therapies for cutaneous melanoma. Hematol Oncol Clin North Am 2014; 28: 491-505
36.  Evans MS, Madhunapantula SV, Robertson GP, Drabick JJ. Current and future trials of targeted therapies in cutaneous melanoma. Adv Exp Med Biol 2013; 779: 223-55
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