Phase II trial of imatinib mesylate in patients with metastatic melanoma

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

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

Personalized therapy in oncology: melanoma as a paradigm for molecular-targeted treatment approaches

In recent decades, the field of systemic cancer treatment has seen remarkable changes due to advancements in the understanding of cancer's biology, immunology, and genetic makeup. As a result, individuals with late-stage cancers are now achieving survival rates that were previously unattainable. The goal of personalized cancer therapy is to enhance clinical outcomes by customizing drug treatments to suit the unique genetic and/or epigenetic profiles of each patient's tumor. This approach aims to reduce the side effects commonly associated with ineffective treatments. Advances in genetic sequencing and molecular cytogenetics have been instrumental in identifying cancer-driving mutations and epigenetic irregularities, leading to the development of specific molecular therapies. This review article highlights the progress and success of targeted molecular therapies in treating malignant melanoma, illustrating the concept of personalized cancer treatment.

Therapeutic Strategies in BRAF V600 Wild-Type Cutaneous Melanoma

There have been many recent advances in melanoma therapy. While 50% of melanomas have a BRAF mutation and are a target for BRAF inhibitors, the remaining 50% are BRAF wild-type. Immune checkpoint inhibitors targeting PD-1, cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and lymphocyte activated gene-3 (Lag-3) are all approved for the treatment of patients with advanced BRAF wild-type melanoma; however, treatment of this patient population following initial immune checkpoint blockade is a current therapeutic challenge given the lack of other efficacious options. Here, we briefly review available US FDA-approved therapies for BRAF wild-type melanoma and focus on developing treatment avenues for this heterogeneous group of patients. We review the basics of genomic features of both BRAF mutant and BRAF wild-type melanoma as well as efforts underway to develop new targeted therapies involving the mitogen-activated protein kinase (MAPK) pathway for patients with BRAF wild-type tumors. We then focus on novel immunotherapies, including developing checkpoint inhibitors and agonists, cytokine therapies, oncolytic viruses and tumor-infiltrating lymphocytes, all of which represent potential therapeutic avenues for patients with BRAF wild-type melanoma who progress on currently approved immune checkpoint inhibitors.

Current State of Melanoma Therapy and Next Steps: Battling Therapeutic Resistance

Melanoma is the most aggressive and deadly form of skin cancer due to its high propensity to metastasize to distant organs. Significant progress has been made in the last few decades in melanoma therapeutics, most notably in targeted therapy and immunotherapy. These approaches have greatly improved treatment response outcomes; however, they remain limited in their abilities to hinder disease progression due, in part, to the onset of acquired resistance. In parallel, intrinsic resistance to therapy remains an issue to be resolved. In this review, we summarize currently available therapeutic options for melanoma treatment and focus on possible mechanisms that drive therapeutic resistance. A better understanding of therapy resistance will provide improved rational strategies to overcome these obstacles.

The treatment of advanced melanoma: Current approaches and new challenges

In recent years, advances in melanoma treatment have renewed patient hope. This comprehensive review emphasizes the evolving treatment landscape, particularly highlighting first-line strategies and the interplay between immune-checkpoint inhibitors (ICIs) and targeted therapies. Ipilimumab plus nivolumab has achieved the best median overall survival, exceeding 70 months. However, the introduction of new ICIs, like relatlimab, has added complexity to first-line therapy decisions. Our aim is to guide clinicians in making personalized treatment decisions. Various features, including brain metastases, PD-L1 expression, BRAF mutation, performance status, and prior adjuvant therapy, significantly impact the direction of advanced melanoma treatment. We also provide the latest insights into the treatment of rare melanoma subtypes, such as uveal melanoma, where tebentafusp has shown promising improvements in overall survival for metastatic uveal melanoma patients. This review provides invaluable insights for clinicians, enabling informed treatment choices and deepening our understanding of the multifaceted challenges associated with advanced melanoma management.

Head and Neck Mucosal Melanoma: Where Are We Now?

PURPOSE OF REVIEW

To highlight recent and relevant treatment considerations while managing mucosal melanoma.

RECENT FINDINGS

Evidence is building to support the use of targeted therapy and immunotherapy while managing mucosal melanoma. Surgical resection with postoperative radiotherapy plays a major role in managing resectable disease. Recent studies evaluate the addition of targeted, and immunotherapies with an attempt to determine the most efficacious sequence of treatment.

Imatinib in c-KIT-mutated metastatic solid tumors: A multicenter trial of Korean Cancer Study Group (UN18-05 Trial)

INTRODUCTION

We conducted an open-label, single-arm, multi-center phase II trial to evaluate the efficacy and safety of imatinib chemotherapy-refractory or metastatic solid tumor patients with c-KIT mutations and/or amplification.

METHODS

c-KIT mutations and amplification were detected using NGS. Imatinib (400 mg daily) was administered continuously in 28-day cycles until disease progression, unacceptable adverse events, or death by any cause. The primary endpoint was the objective response rate (ORR).

RESULT

In total, 18 patients were enrolled on this trial. The most common tumor type was melanoma (n = 15, 83.3%), followed by ovarian cancer, breast cancer, and metastasis of unknown origin (MUO) (each n = 1, 5.5%). The total number of evaluable patients was 17, of which one patient had a complete response, six patients had partial response, and two patients had stable disease. The overall response rate (ORR) of 41.2% (95% CI 17.80-64.60) and a disease control rate of 52.9% (95% CI 29.17-76.63). The median progression-free survival was 2.2 months (95% CI 1.29-3.20), and median overall survival was 9.1 months (95% CI 2.10-16.11). The most common adverse events were edema (31.3%), anorexia (25.0%), nausea (18.8%), and skin rash (18.8%).

CONCLUSION

Imatinib demonstrated modest anti-tumor activity and a manageable safety profile in chemotherapy-refractory solid tumors with c-KIT mutation, especially in melanoma patients.

Nilotinib in KIT-driven advanced melanoma: Results from the phase II single-arm NICAM trial

Mucosal (MM) and acral melanomas (AM) are rare melanoma subtypes of unmet clinical need; 15%-20% harbor KIT mutations potentially targeted by small-molecule inhibitors, but none yet approved in melanoma. This multicenter, single-arm Phase II trial (NICAM) investigates nilotinib safety and activity in KIT mutated metastatic MM and AM. KIT mutations are identified in 39/219 screened patients (18%); of 29/39 treated, 26 are evaluable for primary analysis. Six patients were alive and progression free at 6 months (local radiology review, 25%); 5/26 (19%) had objective response at 12 weeks; median OS was 7.7 months; ddPCR assay correctly identifies KIT alterations in circulating tumor DNA (ctDNA) in 16/17 patients. Nilotinib is active in KIT-mutant AM and MM, comparable to other KIT inhibitors, with demonstrable activity in nonhotspot KIT mutations, supporting broadening of KIT evaluation in AM and MM. Our results endorse further investigations of nilotinib for the treatment of KIT-mutated melanoma. This clinical trial was registered with ISRCTN (ISRCTN39058880) and EudraCT (2009-012945-49).

Acral melanoma: new insights into the immune and genomic landscape

Acral melanoma is a rare subtype of melanoma that arises on the non-hair bearing skin of the nail bed, palms of the hand and soles of the feet. It is unique among melanomas in not being linked to ultraviolet radiation (UVR) exposure from the sun, and, as such, its incidence is similar across populations who are of Asian, Hispanic, African and European origin. Although research into acral melanoma has lagged behind that of sun-exposed cutaneous melanoma, recent studies have begun to address the unique genetics and immune features of acral melanoma. In this review we will discuss the latest progress in understanding the biology of acral melanoma across different ethnic populations and will outline how these new discoveries can help to guide the therapeutic management of this rare tumor.

The pharmacotherapeutic management of nail unit and acral melanomas

INTRODUCTION

Acral and nail unit melanomas are rare subtypes of melanoma, which have poor prognoses. Current guidelines for optimal treatment are lacking. Recent clinical trials have evaluated new pharmacotherapeutic agents for melanoma treatment, with dramatically improved survival rates; however, studies on acral and nail unit melanomas are limited in comparison to trials on cutaneous melanoma.

AREAS COVERED

This is a comprehensive review of the literature regarding the available treatment options for acral and nail unit melanomas, with consideration of safety and tolerability.

EXPERT OPINION

Programmed cell death protein 1 inhibitors are more efficacious than cytotoxic T lymphocyte-associated antigen-4 blockers in acral and nail unit melanomas, although both are well-tolerated. Tyrosine kinase inhibitors have good clinical activity, however, data on safety is relatively limited. There is minimal data on high dose interferon α-2b and cyclin-dependent kinase 4 and 6 inhibitors, and efficacy and safety must be evaluated in future trials before they can be recommended for use in this patient population. Prospective clinical trials on acral and nail unit melanomas are lacking, and must be performed in large patient populations, with international collaboration likely necessary in order to enroll adequate participants.

Effect of surgical treatment for anorectal melanoma: a propensity score-matched analysis of the Surveillance, Epidemiology, and End Results programme data

OBJECTIVE

Anorectal melanoma (AM) is a rare but aggressive tumour with limited information in the existing literature. This study aimed to assess the effect of surgical treatment for AM and predict the prognosis of affected patients.

DESIGN

A retrospective cohort study.

SETTING

Data of patients diagnosed with AM between 1975 and 2016 in the USA were collected from the Surveillance, Epidemiology, and End Results (SEER) database.

PARTICIPANTS

This study enrolled a total of 795 patients with AM from the SEER database and the validation cohort comprised 40 patients with AM enrolled from Chinese institutes.

PRIMARY AND SECONDARY OUTCOME MEASURES

Overall survival (OS) and AM-specific survival (AM-SS).

RESULTS

A total of 795 patients with AM diagnosed between 1975 and 2016 were enrolled in this study. Data over the past four decades showed a trend of increase in incidence rate. A nomogram based on a multivariate Cox regression model was generated to predict AM-SS. The C-index of the nomogram was 0.74 (95% CI 0.71 to 0.77) on internal verification. In the validation cohort, the C-index of the nomogram was 0.72 (95% CI 0.68 to 0.76). The results of propensity score matching (PSM) analysis showed that patients who underwent surgical treatment achieved significant survival (OS: log-rank=17.41, p<0.001; AM-SS: log-rank=14.55, p<0.001). Patients who underwent surgery were stratified into local and extended surgery subgroups. AM-SS and OS were also compared after PSM, but the results were not significantly different between the two surgery subgroups (all p>0.05).

CONCLUSIONS

The nomogram based on the analysis of SEER data showed good performance in predicting OS and AM-SS. Patients with AM can benefit from surgery; however, extensive surgery and appendectomy may not improve AM-SS or OS.

Mechanically activated ion channel Piezo1 contributes to melanoma malignant progression through AKT/mTOR signaling

Melanoma is a highly aggressive cancer that can metastasize at early stage. The aim of this study is to clarify the role of Piezo1 and its potential mechanism in regulating the malignant phenotypes of melanoma. In the present study, we first showed that Piezo1 was abnormally expressed in melanoma, which accelerated the malignant progression by activating AKT/mTOR signaling. Firstly, we found that Piezo1 was upregulated in melanoma and associated with poor survival. Additionally, Piezo1 knockdown significantly weakened intracellular calcium signal and viability of melanoma cells. Furthermore, Piezo1 knockdown inhibited the transendothelial migration and invasion in vitro, as well as metastasis in vivo. Mechanistically, we found that Piezo1 activated AKT/mTOR signaling to maintain malignant phenotypes of melanoma. Therefore, Piezo1 acts as an oncogene in melanoma cells and provides a novel candidate for melanoma diagnosis and treatment.

Melanoma Targeted Therapies beyond BRAF-Mutant Melanoma: Potential Druggable Mutations and Novel Treatment Approaches

Melanomas exhibit the highest rate of somatic mutations among all different types of cancers (with the exception of BCC and SCC). The accumulation of a multimode of mutations in the driver oncogenes are responsible for the proliferative, invasive, and aggressive nature of melanomas. High-resolution and high-throughput technology has led to the identification of distinct mutational signatures and their downstream alterations in several key pathways that contribute to melanomagenesis. This has enabled the development of individualized treatments by targeting specific molecular alterations that are vital for cancer cell survival, which has resulted in improved outcomes in several cancers, including melanomas. To date, BRAF and MEK inhibitors remain the only approved targeted therapy with a high level of evidence in BRAFV600E/K mutant melanomas. The lack of approved precision drugs in melanomas, relative to other cancers, despite harboring one of the highest rates of somatic mutations, advocates for further research to unveil effective therapeutics. In this review, we will discuss potential druggable mutations and the ongoing research of novel individualized treatment approaches targeting non-BRAF mutations in melanomas.

c-Kit inhibitors for unresectable or metastatic mucosal, acral or chronically sun-damaged melanoma: a systematic review and one-arm meta-analysis

BACKGROUND

Activating genomic alterations of the receptor tyrosine kinase KIT are found preferentially in certain melanoma subtypes such as acral and mucosal melanoma or melanoma arising in chronically sun-damaged skin. However, the therapeutic value of c-Kit inhibitors for these subtypes currently remains unclear.

OBJECTIVES

The objective of this study was to summarise the efficacy and safety of c-Kit inhibitors for unresectable or metastatic mucosal, acral or chronically sun-damaged melanoma.

METHODS

We performed a systematic literature research in MEDLINE, Embase and CENTRAL and hand searched pertinent trial registers and conference abstracts for eligible trials until 23rd June 2020. Results were pooled using a random-effects model to calculate pooled proportions of objective response rates (ORRs) and severe adverse events (sAEs) from unselected KIT mutant or amplified cohorts.

RESULTS

Nineteen single-arm studies with an overall sample size of 601 patients were included. The studies investigated imatinib (n = 8), nilotinib (n = 7), dasatinib (n = 3) and sunitinib (n = 1). The pooled ORR for all inhibitors was 15% (95% confidence interval [CI]: 12-18%). Subgroup analysis revealed the highest ORR (20%; 95% CI: 14-26%) for nilotinib. The ORR for mucosal melanoma was 14% (95% CI: 6-24%) and 22% for acral lentiginous melanoma (95% CI: 14-30%). At least one sAE was reported in 42% of patients (95% CI: 34-50%).

CONCLUSIONS

c-Kit inhibitors represent a valuable treatment option for patients with KIT-mutant melanoma, in particular for mutations of exons 11 and 13. Furthermore, high-quality trials are urgently needed to investigate putative combinations of specific targeted therapies with immunotherapy.

Vulvar Melanoma: Molecular Characteristics, Diagnosis, Surgical Management, and Medical Treatment

Ten percent of all women have pigmented vulvar lesions. Fortunately, most of these are benign but 1% of all melanomas in women affect the vulva. While the mortality rate of cutaneous melanoma has dropped by 7% annually during the last 5 years, the prognosis of vulvar melanoma remains dismal: the 5-year overall survival rate is 47% compared with 92% for cutaneous melanoma. The current evidence suggests that this likely results from a combination of delayed diagnosis and different tumor biology, treatment strategies, and treatment response. Although many landmark trials on checkpoint inhibitors included mucosal and vulvar melanomas, the results were often not reported separately. Post-hoc analyses indicate overall response rates between 19 and 37% for checkpoint inhibitors. A recently published retrospective study on vulvar melanomas suggests an objective response in 33.3% with a similar safety profile to cutaneous melanoma. Tyrosine kinase inhibitors may be considered in recurrent disease if a c-KIT mutation is present.

The role of immunotherapy and molecular‑targeted therapy in the treatment of melanoma (Review)

Skin melanomas are malignant neoplasms originating from neuroectodermal melanocytes. Compared to other neoplasms, melanomas have a high rate of growth. Their incidence is highest in Australia and New Zealand, in high‑income European countries (Switzerland, Norway, Sweden) and in the US. In Poland, the standardized incidence rate is approximately 5/100,000. Melanomas are typically highly radioresistant and chemoresistant. Before the era of immunotherapy, inoperable lesions were treated using chemotherapy based mainly on dacarbazine, temozolomide or fotemustine, which did not yield the expected results in terms of extending survival time or improving patient comfort. Therefore, there has emerged a need to seek other solutions. In most cases, the use of immunological treatment or targeted therapy has had a positive impact on survival time and relapse‑free survival. However, these periods are still relatively short, hence the need for further research and improvement of treatment. The most promising strategies appear to be antibodies that block programmed death receptor‑1 (PD‑1) and programmed death receptor ligand‑1 (PD‑L1) molecules, anti‑CTLA4 antibodies (cytotoxic T‑lymphocyte antigen 4) and therapy with BRAF and MEK inhibitors.

Hypoxia-dependent drivers of melanoma progression

Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.

Correlation Between KIT Expression and c-Kit Mutations in 2 Subtypes of Canine Oral Melanocytic Neoplasms

c-Kit mutations have been reported in 15% to 40% of certain human melanoma subtypes, including those histologically similar to canine oral malignant melanomas. Therapeutic response to tyrosine kinase inhibitors has been demonstrated in those human patients. As canine oral malignant melanomas tend to have a poor prognosis despite aggressive surgical removal, evaluation of KIT expression and identification of c-Kit mutations in canine oral melanocytic neoplasms was performed to determine if there is any indication that tyrosine kinase inhibitor drugs might effectively treat any of these cases. This study evaluated 27 canine oral malignant melanomas and 12 canine histologically well-differentiated oral melanocytic neoplasms for activating c-Kit mutations, determined differences in immunohistochemical expression of KIT and c-Kit mutation status, and determined if KIT expression could predict c-Kit mutation status. Among samples that contained intraepithelial nests of neoplastic melanocytes in the KIT-labeled sections, KIT was expressed within cells in these nests in 22/23 (96%) malignant melanomas and 5/7 histologically well-differentiated neoplasms. KIT was expressed in 10% to 30% of neoplastic melanocytes in the lamina propria in 3/24 (13%) malignant melanomas, but 0/9 (0%) histologically well-differentiated neoplasms. Next-generation sequencing identified 85 variants in c-Kit, including 9 nonsynonymous mutations that resulted in amino acid changes predicted to affect protein function. c-Kit mutations with predicted deleterious protein effects were more common in malignant melanomas (8/27 [30%] vs 1/12 [8%]). There was no apparent relationship between detected c-Kit mutations and KIT expression. These results do not support the use of therapies that target c-Kit.

RTK Inhibitors in Melanoma: From Bench to Bedside

MAPK (mitogen activated protein kinase) and PI3K/AKT (Phosphatidylinositol-3-Kinase and Protein Kinase B) pathways play a key role in melanoma progression and metastasis that are regulated by receptor tyrosine kinases (RTKs). Although RTKs are mutated in a small percentage of melanomas, several receptors were found up regulated/altered in various stages of melanoma initiation, progression, or metastasis. Targeting RTKs remains a significant challenge in melanoma, due to their variable expression across different melanoma stages of progression and among melanoma subtypes that consequently affect response to treatment and disease progression. In this review, we discuss in details the activation mechanism of several key RTKs: type III: c-KIT (mast/stem cell growth factor receptor); type I: EGFR (Epidermal growth factor receptor); type VIII: HGFR (hepatocyte growth factor receptor); type V: VEGFR (Vascular endothelial growth factor), structure variants, the function of their structural domains, and their alteration and its association with melanoma initiation and progression. Furthermore, several RTK inhibitors targeting the same receptor were tested alone or in combination with other therapies, yielding variable responses among different melanoma groups. Here, we classified RTK inhibitors by families and summarized all tested drugs in melanoma indicating the rationale behind the use of these drugs in each melanoma subgroups from preclinical studies to clinical trials with a specific focus on their purpose of treatment, resulted effect, and outcomes.

Extracutaneous Melanoma

Extracutaneous melanomas (ECMs) represent a heterogeneous group of melanoma subtypes characterized by distinct clinical and biological features from cutaneous melanoma. These subtypes share an aggressive natural history with high mortalities compared with nonacral cutaneous melanoma (NACM). Although recent advances in NACM have made significant improvements in morbidity and mortality, ECMs continue to lag behind. As the pathogenesis and molecular features of these rare subtypes continue to emerge, therapeutic research has aimed to closing the gap.

Anorectal melanoma – histopathological and immunohistochemical features and treatment

Anorectal melanomas should be characterized by location (anal, rectal and anorectal), color, size, shape and mobility and microscopically, by melanocyte subtypes, grade of melanin pigmentation, junctional changes in the squamous epithelium, atypical mitotic index, cellular atypia, inflammatory infiltrate, vascular and perineural invasion, sentinel lymph node, and anorectal parietal penetration. Anorectal melanomas must be staged by American Joint Committee on Cancer (AJCC) and/or TNM Classification of Malignant Tumours (TNM) criteria. As melanocytes can present with several shapes, sometimes the differential diagnosis with other tumors in this region may be difficult. Because of this, immunohistochemistry is mandatory to attain a precise diagnosis. This study is a report of 14 patients with anorectal melanoma, in whom histological examinations were remade and immunohistochemistry was performed with several markers for melanocytes and for other tumor cells of the anorectal region, properly establishing the diagnosis. The most rational surgery is the extended local resection, when the disease is restricted to the area or the abdominoperineal resection to advanced lesions. Regardless of the technique used, the results are always poor. The authors deny any efficacy of current radio and/or chemotherapy as part of treatment of anorectal melanoma. Target-therapy for metastatic disease has been considered a good strategy, but the results are still inconclusive.

Tumor Microenvironment-Associated Pericyte Populations May Impact Therapeutic Response in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy, and aggressive radioactive iodine refractory thyroid carcinomas still lack an effective treatment. A deeper understanding of tumor heterogeneity and microenvironment will be critical to establishing new therapeutic approaches. One of the important influencing factors of tumor heterogeneity is the diversity of cells in the tumor microenvironment. Among these are pericytes, which play an important role in blood vessel stability and angiogenesis, as well as tumor growth and metastasis. Pericytes also have stem cell-like properties and are a heterogeneous cell population, and their lineage, which has been challenging to define, may impact tumor resistance at different tumor stages. Pericytes are also important stroma cell types in the angiogenic microenvironment which express tyrosine-kinase (TK) pathways (e.g., PDGFR-β). Although TK inhibitors (TKI) and BRAF^V600E inhibitors are currently used in the clinic for thyroid cancer, their efficacy is not durable and drug resistance often develops. Characterizing the range of distinct pericyte populations and distinguishing them from other perivascular cell types may enable the identification of their specific functions in the thyroid carcinoma vasculature. This remains an essential step in developing new therapeutic strategies. Also, assessing whether thyroid tumors hold immature and/or mature vasculature with pericyte populations coverage may be key to predicting tumor response to either targeted or anti-angiogenesis therapies. It is also critical to apply different markers in order to identify pericyte populations and characterize their cell lineage. This chapter provides an overview of pericyte ontogenesis and the lineages of diverse cell populations. We also discuss the role(s) and targeting of pericytes in thyroid carcinoma, as well as their potential impact on precision targeted therapies and drug resistance.

Emerging strategies to treat rare and intractable subtypes of melanoma

Melanoma is the deadliest form of skin cancer, possessing a diverse landscape of subtypes with distinct molecular signatures and levels of aggressiveness. Although immense progress has been achieved therapeutically for patients with the most common forms of this disease, little is known of how to effectively treat patients with rarer subtypes of melanoma. These subtypes include acral lentiginous (the rarest form of cutaneous melanoma; AL), uveal, and mucosal melanomas, which display variations in distribution across (a) the world, (b) patient age-groups, and (c) anatomic sites. Unfortunately, patients with these relatively rare subtypes of melanoma typically respond worse to therapies approved for the more common, non-AL cutaneous melanoma and do not have effective alternatives, and thus consequently have worse overall survival rates. Achieving durable therapeutic responses in these high-risk melanoma subtypes represents one of the greatest challenges of the field. This review aims to collate and highlight effective preclinical and/or clinical strategies against these rare forms of melanoma.

Immunohistochemical study of CD117 in various cutaneous melanocytic lesions

The aim of the present study was to carried out a comparative immunohistochemical evaluation of CD117 (c-Kit), a biomarker that evaluates both tumor progression and prognosis, in different melanocytic lesions, to emphasize the significance of this biomarker in malignant melanoma (MM). The study was performed on 55 cases, represented by a control group, which included 5 cases of simple nevi and 5 cases of dysplastic nevi, as well as a study group consisting of 35 cases of primary MM and 10 metastases (one intestinal, 3 cutaneous - one satellite and two distant as well as 6 in the lymph nodes). The study group included 15 cases of superficial spreading melanoma (SSM), 10 cases of nodular melanoma (NM), 3 lentigo maligna melanoma (LMM), 3 cases of acral lentiginous melanoma (ALM) and 4 cases of amelanotic MM. CD117 was found to be massively involved in the process of tumorigenesis of cutaneous malignancies, being immunohistochemically undetectable in benign neural lesions, but densely expressed in dysplastic lesions and in situ melanoma areas. In invasive cutaneous MMs, CD117 expression tended to decrease with neoplasia progression proceding into the tumorigenic, vertical growth phase, being lower in the profound dermal component of tumors and in nodular MMs. To eliminate the epidermal barriers and gain a proliferative advantage to allow the transition to the vertical growth phase, it seems that MM should lose expression of c-Kit. Cutaneous metastases were found to express CD117 at a level comparable to their primary tumors, suggesting that other mechanisms interfere directly with the metastatic process and not loss of c-Kit expression by itself. CD117 overexpression in cutaneous melanocytic lesions correlates significantly with increased immunostaining intensity, suggesting that the immunohistochemical evaluation of CD117 may be a good method for screening patients, who could benefit from personalized therapy with tyrosine kinase inhibitors.

Uncommon Subtypes of Malignant Melanomas: A Review Based on Clinical and Molecular Perspectives

Malignant melanoma represents the most aggressive type of skin cancer. Modern therapies, including targeted agents and immune checkpoint inhibitors, have changed the dismal prognosis that characterized this disease. However, most evidence was obtained by studying patients with frequent subtypes of cutaneous melanoma (CM). Consequently, there is an emerging need to understand the molecular basis and treatment approaches for unusual melanoma subtypes. Even a standardized definition of infrequent or rare melanoma is not clearly established. For that reason, we reviewed this challenging topic considering clinical and molecular perspectives, including uncommon CMs-not associated with classical V600E/K BRAF mutations-malignant mucosal and uveal melanomas, and some unusual independent entities, such as amelanotic, desmoplastic, or spitzoid melanomas. Finally, we collected information regarding melanomas from non-traditional primary sites, which emerge from locations as unique as meninges, dermis, lymph nodes, the esophagus, and breasts. The aim of this review is to summarize and highlight the main scientific evidence regarding rare melanomas, with a particular focus on treatment perspectives.

Successful treatment with avapritinib in patient with mucosal metastatic melanoma

Metastatic vulvar melanoma is a rare and aggressive disease and survival is usually poor. Vulvar melanomas harbor BRAF V600 mutations only infrequently; consequently, target therapy is a rare therapeutic option and immunotherapy usually has only a weak effect. On the other hand, KIT mutations are rare in cutaneous melanomas, but relatively frequent in mucosal melanomas, particularly in vulvar-vaginal melanomas, and can be a therapeutic target. Herein, we report a clinical case of a patient with metastatic vulvar melanoma, harboring an exon 17 c-KIT mutation, treated with avapritinib (BLU-285) – a highly potent and selective oral kinase inhibitor designed to treat imatinib-resistant gastro-intestinal stromal tumors (GIST) by targeting KIT/PDGFRα activation loop mutants (exons 17/18). After failure of the combination of ipilimumab + nivolumab first and then nivolumab alone, the patient received avapritinib 300 mg/daily for central nervous system (CNS), lymph-nodal, right adrenal gland, lung, and subcutaneous metastases. Best response was partial remission, according to RECIST 1.1 criteria. Time to treatment progression was 11 months. Main toxicities were grade 2 cutaneous vasculitis that required avapritinib discontinuation, and grade 2 uveitis of unknown origin, treated by vitrectomy and empiric antibiotic and antiviral therapy due to negative cultural tests. Uveitis was detected at the time of progression and therapy was definitively discontinued. In conclusion, avapritinib proved to be effective even in the presence of a pretreated disease, a high tumor burden, and brain metastases. In our experience, treatment was feasible and toxicity manageable. Considering the lack of effective therapies and the poor outcome of the disease, determination of c-KIT mutations should be performed routinely in cases of metastatic mucosal melanoma.

Treatment Strategies and Survival Trends for Anorectal Melanoma: Is it Time for a Change?

BACKGROUND

Immunotherapy advances for the treatment of cutaneous melanoma question its efficacy in treating anorectal mucosal melanoma (ARMM). We aimed to identify the prevalence, current management, and overall survival (OS) for ARMM.

METHODS

Review of patients with ARMM from 2004 to 2015 National Cancer Database. Factors associated with immunotherapy were identified using multivariable logistic regression. The primary outcome was 2- and 5-year OS. Subgroup analysis by treatment type was performed.

RESULTS

A total of 1331 patients were identified with a significant increase in prevalence (2004: 6.99%, 2015: 10.53%). ARMM patients were older, white, on Medicare, and from the South. The most common treatment was surgery (48.77%), followed by surgery + radiation (11.75%), surgery + immunotherapy (8.68%), and surgery + chemotherapy (8.68%). 16.93% of patients received immunotherapy, with utilization increasing (7.24%: 2004, 21.27%: 2015, p < 0.001). Patients who received immunotherapy had a significantly better 2-year OS (42.47% vs. 49.21%, p < 0.001), and other therapies did not reveal a significant difference. Adjusted analysis showed no difference in 2- and 5-year OS based on therapy type.

CONCLUSION

The prevalence of ARMM has increased. The use of immunotherapy has increased substantially. Some survival benefit with the administration of immunotherapy may exist that has yet to be revealed. A more aggressive treatment paradigm is warranted.

Principles of Targeted Therapy for Melanoma

Targeted BRAF and MEK inhibition has become an appropriate first-line treatment of BRAF-mutant advanced cutaneous melanoma. The authors present an overview of the MAPK pathway as well as the other major pathways implicated in melanoma development. Melanoma brain metastases are a devastating complication of melanoma that can be traced to derangements in cell signaling pathways, and the current evidence for targeted therapy is reviewed. Finally, activating KIT mutations are rarely found to cause melanomas and may provide an actionable target for therapy. The authors review the current evidence for targeted KIT therapy and summarize the ongoing clinical trials.

An Update Regarding the Molecular Genetics of Melanocytic Neoplasms and the Current Applications of Molecular Genetic Technologies in Their Diagnosis and Treatment

Molecular genetic technologies are used to aid in diagnosis and treatment of borderline melanocytic tumors as an adjuvant to the gold standard histopathologic evaluation. A specific set of fluorescence in situ hybridization probes is widely used to aid in diagnosing challenging melanocytic lesions. New melanoma probe cocktails have revealed increased sensitivity and specificity in ambiguous melanocytic cases. Array comparative genomic hybridization is a more complex technology used for the work-up of diagnostically problematic Spitzoid melanocytic proliferations. Cutting-edge technologies, including next-generation sequencing and cell-free nucleic acid analysis, are promising biomarker applications for mutation detection towards personalized patient management.

Targeted Therapy and Immunotherapy for Melanoma in Japan

OPINION STATEMENT

Melanoma has several clinically and pathologically distinguishable subtypes, which also differ genetically. Mutation patterns vary among different melanoma subtypes, and efficacy of immune-checkpoint inhibitors differs depending on the subtype of melanoma. In spite of the recent revolution of systemic therapies for advanced melanoma, access to innovative agents is still restricted in many countries. This review article aimed to describe the epidemiology and current status of systemic therapies for melanoma in Japan, where melanoma is rare, but access to innovative agents is available. Acral and mucosal melanomas, which are common in Asian populations, predominantly occur in sun-protected areas and share several biological features. Both the melanomas harbor KIT mutation in approximately 15% of the cases; BRAF or NRAS mutation is found in approximately 10-15% of acral melanoma, but these mutations are less frequent in mucosal melanoma. Combined use of BRAF and MEK inhibitors is one of the standards of care for patients with advanced BRAF-mutant melanoma. In patients with melanoma harboring KIT mutation in exon 11 or 13, KIT inhibitors can be a treatment option; however, none of them have been approved in Japan. Immune-checkpoint inhibitors are expected to be less effective against acral and mucosal melanomas because their somatic mutation burden is lower than those in non-acral cutaneous melanomas. A recently completed phase II trial of nivolumab and ipilimumab combination therapy in 30 Japanese patients with melanoma, including seven with acral and 12 with mucosal melanoma, demonstrated an objective response rate of 43%. Regarding oncolytic viruses, canerpaturev (C-REV, also known as HF10) and talimogene laherparepvec (T-VEC) are currently under review in early phase trials. In the adjuvant setting, dabrafenib plus trametinb combination, nivolumab monotherapy, and pembrolizumab monotherapy were approved in July, August, and December 2018 in Japan, respectively. However, most of the adjuvant phase III trials excluded patients with mucosal melanoma. A phase III trial of adjuvant therapy with locoregional interferon (IFN)-β versus surgery alone is ongoing in Japan (JCOG1309, J-FERON), in which IFN-β is injected directly into the site of the primary tumor postoperatively, so that it would be drained through the untreated lymphatic route to the regional node basin. After the recent approval of these new agents, the JCOG1309 trial will be revised to focus on patients with stage II disease. In conclusion, acral and mucosal melanomas have been treated based on the available medical evidence for the treatment of non-acral cutaneous melanomas. Considering the differences in genetic backgrounds and therapeutic efficacy of immunotherapy, specialized therapeutic strategies for these subtypes of melanoma should be established in the future.

Antiproliferative effects of imatinib mesylate on ZR‑75‑1 and MDA‑MB‑231 cell lines via PDGFR‑β, PDGF‑BB, c‑Kit and SCF expression

Imatinib mesylate is an anti‑neoplastic targeted chemotherapeutic agent, which can inhibit tyrosine kinase receptors, including BCR‑ABL, platelet‑derived growth factor receptors (PDGFRs) and c‑Kit. Cellular processes, including differentiation, proliferation and survival are regulated by these receptors. The present study aimed to evaluate the antiproliferative effects of imatinib mesylate, and its effects on apoptotic induction and cell cycle arrest in breast cancer cell lines. In addition, the study aimed to determine whether the effects of this drug were associated with the mRNA and protein expression levels of PDGFR‑β, c‑Kit, and their corresponding ligands PDGF‑BB and stem cell factor (SCF), which may potentially modulate cell survival and proliferation. To assess the antiproliferative effects of imatinib mesylate, an MTS assay was conducted following treatment of cells with 2‑10 µM imatinib mesylate for 96, 120 and 144 h; accordingly the half maximal inhibitory concentration of imatinib mesylate was calculated for each cell line. In addition, the proapoptotic effects and cytostatic activity of imatinib mesylate were investigated. To evaluate the expression of imatinib‑targeted genes, PDGFR‑β, c‑Kit, PDGF‑BB and SCF, under imatinib mesylate treatment, mRNA expression was detected using semi‑quantitative polymerase chain reaction and protein expression was detected by western blot analysis in ZR‑75‑1 and MDA‑MB‑231 breast carcinoma cell lines. Treatment with imatinib mesylate suppressed cell proliferation, which was accompanied by apoptotic induction and cell cycle arrest in the investigated cell lines. In addition, PDGFR‑β, PDGF‑BB, c‑Kit and SCF were expressed in both breast carcinoma cell lines; PDGFR‑β and c‑Kit, as imatinib targets, were downregulated in response to imatinib mesylate treatment. The present results revealed that at least two potential targets of imatinib mesylate were expressed in the two breast carcinoma cell lines studied. In conclusion, the antiproliferative, cytostatic and proapoptotic effects of imatinib mesylate may be the result of a reduction in the expression of c‑Kit and PDGFR tyrosine kinase receptors, thus resulting in suppression of the corresponding ligand PDGF‑BB. Therefore, imatinib mesylate may be considered a promising target therapy for the future treatment of breast cancer.

Cancer chemotherapeutics in rheumatoid arthritis: A convoluted connection

Chemotherapy is one of the most popular therapeutic strategies to treat cancer. However, cancer chemotherapeutics have often been associated with impairment of the immune system, which might consequently lead to an augmented risk of autoimmune disorders, such as rheumatoid arthritis. Though the accurate mechanistic facets of rheumatoid arthritis induction have not been interpreted yet, a conglomeration of genetic and environmental factors might promote its etiology. What makes the scenario more challenging is that patients with rheumatoid arthritis are at a significantly elevated risk of developing various types of cancer. It is intriguing to note that diverse cancer chemotherapy drugs are also commonly used to treat symptoms of rheumatoid arthritis. However, a colossal multitude of such cancer therapeutics has demonstrated highly varied results in rheumatoid arthritis patients, including both beneficial and adverse effects. Herein, we attempt to present a holistic account of the variegated modalities of this complex tripartite cross-talk between cancer, rheumatoid arthritis and chemotherapy drugs in order to decode the sinuous correlation between these two appalling pathological conditions.

Emerging Biomarkers in Cutaneous Melanoma

Earlier identification of aggressive melanoma remains a goal in the field of melanoma research. With new targeted and immune therapies that have revolutionized the care of patients with melanoma, the ability to predict progression and monitor or predict response to therapy has become the new focus of research into biomarkers in melanoma. In this review, promising biomarkers are highlighted. These biomarkers have been used to diagnose melanoma as well as predict progression to advanced disease and response to therapy. The biomarkers take various forms, including protein expression at the level of tissue, genetic mutations of cancer cells, and detection of circulating DNA. First, a brief description is provided about the conventional tissue markers used to stage melanoma, including tumor depth. Next, protein biomarkers, which provide both diagnostic and prognostic information, are described. This is followed by a discussion of important genetic mutations, microRNA, and epigenetic modifications that can provide therapeutic and prognostic material. Finally, emerging serologic biomarkers are reviewed, including circulating melanoma cells and exosomes. Overall the goal is to identify biomarkers that aid in the earlier identification and improved treatment of aggressive melanoma.

Anorectal mucosal melanoma

Anorectal melanoma is an uncommon and aggressive mucosal melanocytic malignancy. Due to its rarity, the pre-operative diagnosis remains difficult. The first symptoms are non-specific such as anal bleeding, anal mass or pain. Although anorectal melanoma carries a poor prognosis; optimal therapeutics strategies are unclear. Surgical resection remains the mainstay of treatment. The optimal surgical procedure for primary tumours is controversial and can vary from wide local excision or endoscopic mucosal resection (EMR) to an abdomino-perineal resection. A high degree of uncertainly exists regarding the benefit of radiation therapy or chemotherapy. The treatment of advanced melanoma is evolving rapidly with better understanding of the disease biology and immunology. Considerable effort has been devoted to the identification of molecular determinants of response to target therapies and immunotherapy.

Treatment of advanced melanoma - A changing landscape

Following decades of relative ostracism, advances in the treatment of melanoma have brought a new reality for patients, physicians and researchers. While antibodies targeting molecules involved in the modulation of the interaction between melanoma and immune cells changed the meaning of the term "cancer immunotherapy," a better characterization of the molecular aberrations involved in melanoma carcinogenesis prompted the development of inhibitors of the mitogen-activated protein kinase pathway (MAPK) that also led to significant improvements both in response rates and survival. As a result, new drugs have been approved for clinical use in the United States and Europe, including the immune-checkpoint blockers ipilmumab, pembrolizumab and nivolumab, the oncolytic herpesvirus talimogene laherparepvec, and the targeted-agents vemurafenib, dabrafenib, cobimetinib and trametinib. In this article, we review the results of studies that brought new approaches to the bedside and discuss how these developments are being incorporated into the care of patients in Brazil.

An Update on Randomized Clinical Trials in Melanoma

Despite many advances in the treatment of melanoma, it still continues to be a disease that affects many people. Fortunately, there have been a multitude of randomized trials that have refined the treatment of this prevalent disease. From 1975 to 2000, there were 154 prospective randomized trials on the treatment of local, regional, and metastatic melanoma. From 2001 to now, additional randomized trials have focused on the role of surgery, adjuvants to surgery, and treatment of metastatic disease. The results of the practice-changing trials are summarized in this review.

STAT3 Mediates Nilotinib Response in KIT-Altered Melanoma: A Phase II Multicenter Trial of the French Skin Cancer Network

Mutated oncogenic KIT is a therapeutic target in melanoma. We conducted a multicenter phase II trial on the KIT inhibitor nilotinib in patients with unresectable melanoma harboring KIT alteration. The primary endpoint was the response rate (complete response or partial response following Response Evaluation Criteria in Solid Tumors criteria) at 6 months. Pharmacodynamic studies using KIT sequencing, qPCR array, and immunostaining of downstream KIT effectors were performed during treatment. Twenty-five patients were included and received 400 mg oral nilotinib twice daily. At 6 months, nilotinib induced tumor response in four patients. The best overall response rate was 20% and the disease control rate was 56%, limited to patients harboring exon 11 or 13 mutations. Four patients exhibited durable response, including three persisting (3.6 and 2.8 years for two patients with stage IIIC and 2.5 years for one with IVM1b melanoma). A reduction in signal transducer and activator of transcription (STAT) 3 phosphorylation and its effectors (BCL-2, MCL-1) in tumors during follow-up was significantly associated with clinical response. In the KIT-mutated melanoma cell line M230, nilotinib reduced STAT3 signaling and STAT inhibitors were as efficient as KIT inhibitors in reducing cell proliferation. Our study evidences a significant association between STAT3 inhibition and response to nilotinib, and provides a rationale for future research assessing STAT inhibitors in KIT-mutated melanoma.

The clinical significance of c-Kit mutations in metastatic oral mucosal melanoma in China

c-Kit mutations are frequently detected in mucosal melanomas, but their clinical significance in metastatic oral mucosal melanomas (OMM) remains unclear. The main purpose of this study was to investigate the clinical and pathological features of metastatic OMMs with c-Kit mutations and the efficiency of the tyrosine kinase inhibitor imatinib in treating metastatic OMMs. We found thatresidual primary lesion and neck lymph nodes could act as independent prognostic factors in metastatic OMM patients. c-Kit mutations were detected in 22 out of 139 (15.8%) metastatic OMM patients. Under chemotherapy, the overall survival (OS) of c-Kit mutant patients was significantly shorter than that of wild-type patients. The Ki67 expression was significantly higher in c-Kit mutant patients than in wild-type patients. In distant metastatic OMM patients with c-Kit mutations, the treatment with c-Kit inhibitor resulted in a better OS. In conclusion, residual primary lesion, cervical lymph nodes and c-Kit mutations act as adverse prognostic factors of metastatic OMMs. The Kit inhibitor imatinib could benefit metastatic OMM patients with c-Kit mutations.

Phase I clinical trial of combination imatinib and ipilimumab in patients with advanced malignancies

Background

Imatinib mesylate can induce rapid tumor regression, increase tumor antigen presentation, and inhibit tumor immunosuppressive mechanisms. CTLA-4 blockade and imatinib synergize in mouse models to reduce tumor volume via intratumoral accumulation of CD8+ T cells. We hypothesized that imatinib combined with ipilimumab would be tolerable and may synergize in patients with advanced cancer.

Methods

Primary objective of the dose-escalation study (3 + 3 design) was to establish the maximum tolerated dose (MTD) and recommended phase II dose. Secondary objectives included evaluation of antitumor activity of the combination based on KIT mutation status and the capacity of tumor-associated immune biomarkers to predict response.

Results

The primary objective to establish the maximum tolerated dose (MTD) was achieved, and the recommended phase II doses are ipilimumab at 3 mg/kg every 3 weeks and imatinib 400 mg twice daily. Of the 35 patients treated in the escalation and GIST expansion, none experienced dose-limiting toxicities. The most common grade 1/2–related adverse events (AEs) were fatigue (66%), nausea (57%), anorexia, vomiting (each 31%), edema (29%), and anemia, diarrhea, and rash (each 23%). Grade 3 AEs occurred in 6 patients (17%) and included fatigue, anemia, fever, rash, and vomiting. There were no grade 4 AEs. In general, the combination was well tolerated. Among all patients, 2 responses were seen: 1 partial response (GIST) and 1 partial response (melanoma). Stable disease was seen in 6 patients lasting an average of 6 months. The melanoma responder was KIT mutated and the GIST responder was wild-type.

Conclusions

Our findings suggest that this combination of a targeted agent with checkpoint blockade is safe across multiple tumor types. Low activity with no clear signal for synergy was observed in escalation or GIST expansion cohorts. Assessment of antitumor activity of this combination in the KIT-mutant melanoma population is being evaluated.

Trial registration

Clinicaltrials.gov NCT01738139, registered 28 November 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0238-1) contains supplementary material, which is available to authorized users.

Recent advances in molecular genetics of melanoma progression: implications for diagnosis and treatment

According to the multi-step carcinogenesis model of cancer, initiation results in a benign tumor and subsequent genetic alterations lead to tumor progression and the acquisition of the hallmarks of cancer. This article will review recent discoveries in our understanding of initiation and progression in melanocytic neoplasia and the impact on diagnostic dermatopathology.

The Rapid Emergence of Novel Therapeutics in Advanced Malignant Melanoma

For decades, no cancer therapy had been shown to improve average survival in metastatic melanoma. Two critical events have occurred, the discovery of melanoma driver mutation subsets and the discovery of immune checkpoint inhibitors, which have allowed for the development of modern, effective therapies. These findings have facilitated a rapid emergence of novel therapeutics for the disease with multiple FDA approvals in the last several years. The drugs vemurafenib, trametinib, and dabrafenib, which inhibit the commonly mutated BRAF pathway, have been approved based on improvements in survival outcomes. Agents that block immune checkpoints on lymphocytes allowing for immune cell activity against melanoma have also been approved based on improved survival outcomes such as ipilimumab and nivolumab. Pembrolizumab, another immune checkpoint inhibitor, has also been approved based on the response rate and duration of response in a phase 1 trial. Further agents and combinations of approved agents are positioned to possibly further increase this tally of approved drugs. This review will discuss recently approved novel agents and select drugs in development in advanced melanoma.

Phase 2 study of sunitinib in patients with metastatic mucosal or acral melanoma

BACKGROUND

Patients with mucosal and acral melanomas have limited treatment options and a poor prognosis. Mutations of the KIT oncogene in these melanoma subtypes provide a potential therapeutic target.

METHODS

A multicenter phase 2 trial of sunitinib was conducted in patients with unresectable stage III or IV melanoma of a mucosal or acral primary origin. Patients were treated in 2 cohorts: cohort A received sunitinib at a dose of 50 mg daily for 4 weeks of a 6-week cycle, and cohort B received sunitinib at a dose of 37.5 mg daily on a continuous basis. Dose reductions were permitted for treatment-related toxicities, and tumor assessments were performed every 2 months.

RESULTS

Fifty-two patients were enrolled: 21 in cohort A and 31 in cohort B. Four patients had confirmed partial responses, which lasted 5 to 10 months (1 with a KIT mutation). In both cohorts, the proportion of patients alive and progression-free at 2 months was 52% (95% confidence interval, 38%-66%); this was significantly larger than the hypothesized null of 5%. There was no significant difference in response or overall survival between the 25% of patients with a KIT mutation and those without one (response rate, 7.7% vs 9.7%; overall survival, 6.4 vs 8.6 months). The overall disease control rate was 44%, and a high rate of toxicity was associated with the treatment.

CONCLUSIONS

Sunitinib showed activity in the treatment of mucosal and acral melanoma that was not dependent on the presence of a KIT mutation. However, the medication was poorly tolerated, and there were no prolonged responses. Cancer 2015;121:4007-4015. © 2015 American Cancer Society.

KIT in melanoma: many shades of gray

Activating mutations in KIT have been identified in melanomas of acral and mucosal types and in those arising in chronically sun-damaged skin. Until now, KIT has been considered an oncogenic driver and a potential therapeutic target. However, data presented by Dhal et al. show that in cutaneous melanomas the KIT promoter is a target for hypermethylation, leading to its downregulation. Their observations suggest that signaling pathways downstream of KIT may have distinct and opposing roles in the pathogenesis of melanoma subtypes. This will have important implications for the use of KIT inhibitors in treating melanomas.

Blinded by the light: why the treatment of metastatic melanoma has created a new paradigm for the management of cancer

Until recently, treatment for metastatic melanoma was characterised by a limited availability of treatment options that offer objective survival benefit. Cytotoxic agents fundamentally lack the ability to achieve disease control and cytokine therapy with interleukin-2 has an unacceptably high - for the use across all patient cohorts - rate of toxicities. The validation of braf as an oncogene driving melanoma tumorigenesis, as well as the discovery of the role of CTLA-4 receptor in the evasion of anticancer immune response by melanoma, has revolutionised our treatment options against a disease with dismal prognosis. Quick implementation of translational discoveries brought about BRAF/MEK inhibition in clinic, while at the same time, wider experience with CTLA-4 blockade enabled clinicians to manage previously fatal immune-related toxicities with greater confidence. The suitability for clinical use of other oncogenic drivers such as NRAS and c-kit is currently being tested whilst the PD-1/PD-L1/PD-L2 axis has emerged as a new immunotherapy target with exciting early phase results. The recent exponential progress in treatment of melanoma has set an example of translational medicine and the current review aims to explain why, as well as suggesting new goals for the future.

Targeting drivers of melanoma with synthetic small molecules and phytochemicals

Melanoma is the least common form of skin cancer, but it is responsible for the majority of skin cancer deaths. Traditional therapeutics and immunomodulatory agents have not shown much efficacy against metastatic melanoma. Agents that target the RAS/RAF/MEK/ERK (MAPK) signaling pathway - the BRAF inhibitors vemurafenib and dabrafenib, and the MEK1/2 inhibitor trametinib - have increased survival in patients with metastatic melanoma. Further, the combination of dabrafenib and trametinib has been shown to be superior to single agent therapy for the treatment of metastatic melanoma. However, resistance to these agents develops rapidly. Studies of additional agents and combinations targeting the MAPK, PI3K/AKT/mTOR (PI3K), c-kit, and other signaling pathways are currently underway. Furthermore, studies of phytochemicals have yielded promising results against proliferation, survival, invasion, and metastasis by targeting signaling pathways with established roles in melanomagenesis. The relatively low toxicities of phytochemicals make their adjuvant use an attractive treatment option. The need for improved efficacy of current melanoma treatments calls for further investigation of each of these strategies. In this review, we will discuss synthetic small molecule inhibitors, combined therapies and current progress in the development of phytochemical therapies.

RSK1 activation promotes invasion in nodular melanoma

The two major melanoma histologic subtypes, superficial spreading and nodular melanomas, differ in their speed of dermal invasion but converge biologically once they invade and metastasize. Herein, we tested the hypothesis that distinct molecular alterations arising in primary melanoma cells might persist as these tumors progress to invasion and metastasis. Ribosomal protein S6 kinase, 90 kDa, polypeptide 1 (RSK1; official name RPS6KA1) was significantly hyperactivated in human melanoma lines and metastatic tissues derived from nodular compared with superficial spreading melanoma. RSK1 was constitutively phosphorylated at Ser-380 in nodular but not superficial spreading melanoma and did not directly correlate with BRAF or MEK activation. Nodular melanoma cells were more sensitive to RSK1 inhibition using siRNA and the pharmacological inhibitor BI-D1870 compared with superficial spreading cells. Gene expression microarray analyses revealed that RSK1 orchestrated a program of gene expression that promoted cell motility and invasion. Differential overexpression of the prometastatic matrix metalloproteinase 8 and tissue inhibitor of metalloproteinases 1 in metastatic nodular compared with metastatic superficial spreading melanoma was observed. Finally, using an in vivo zebrafish model, constitutive RSK1 activation increased melanoma invasion. Together, these data reveal a novel role for activated RSK1 in the progression of nodular melanoma and suggest that melanoma originating from different histologic subtypes may be biologically distinct and that these differences are maintained as the tumors invade and metastasize.