Mutational profiling of acral melanomas in Korean populations

BRAF V600E Mutations and Beyond: A Molecular Perspective of Melanoma from a Tertiary Cancer Referral Center of India

Vaibhavi VengurlekarObjectives  Malignant melanoma demonstrates frequently occurring mutations of genes in the serine/threonine kinase pathway, namely BRAF, NRAS, and neurofibromin 1. There is rare documentation of a detailed analysis of these mutations in cases of melanoma among Indian patients. We present molecular features in cases of malignant melanoma, diagnosed at a tertiary cancer referral center in India, over a period of 8 years (2011-2018). Materials and Methods  This study was performed on formalin fixed paraffin embedded tissues of 88 histologically confirmed cases of malignant melanoma. BRAF gene alterations were studied by both Sanger sequencing and real-time polymerase chain reaction techniques ( n  = 74). Molecular testing for BRAF and NRAS gene alterations was accomplished in 74/88 cases (80%). Molecular test results were correlated with clinicopathological features using IBM SPSS Statistical software 25.0. Results  The age ranged from 13 to 79 years (median = 57), with a M:F ratio of 1.4:1. BRAF mutations were observed in 12/74 (16.21%) patients, including V600E ( n  = 7), A594T ( n  = 1), T599 = ( n  = 2), V600K ( n  = 1), and Q612P ( n  = 1), while NRAS mutations were observed in 6/38 (15.7%) patients. Among various subtypes, nodular melanoma was the most frequent subtype (33%) among cutaneous malignant melanomas. Among non-cutaneous melanomas, mucosal melanomas were observed in 37.5% of cases. Conclusion  This constitutes one of the few reports on comprehensive analysis of molecular alterations underlying melanomas in Indian patients. A larger sample size, with more extensive molecular markers, would yield additional information on the disease manifestation.

Multiple primary malignant neoplasm: Case report and comprehensive literature review

Multiple primary tumors, especially quadruple primary tumors, are extremely rare clinically, and there is no standard protocol for clinical management. We described a case in which a bone tumor, a malignant bladder tumor, a malignant melanoma, and an intrahepatic cholangiocarcinoma were all original malignancies. The patient is a 79-year-old woman who underwent surgery for a left middle finger bone tumor 45 years ago, as well as surgery for bladder malignancy and postoperative adjuvant chemotherapy 15 years ago, and the precise pathological results and treatment are unclear. One year ago, she underwent amputation of the toe due to a black mass of the right toe and was diagnosed pathologically as a freckled malignant melanoma of the extremity. Prior to postoperative adjuvant systemic medication, PET/CT revealed malignancy in the lateral segment of the left lobe of the liver, and multiple lymphadenopathies in the left parotid gland, hilar hepatic, and retroperitoneal region. Intrahepatic cholangiocarcinoma was found in the liver puncture biopsy's pathology report. The serum sample's next-generation sequencing (NGS) revealed a missense mutation, designated P.G12V, in exon 2 of the KRAS gene. Based on patients with malignant melanoma and intrahepatic cholangiocarcinoma, she received 6 cycles of GP (gemcitabine/cisplatin) combined with Camrelizumab systemic therapy, and followed by 3 cycles of Camrelizumab maintenance therapy, the efficacy was evaluated as stable disease (SD) during treatment. When the 4th cycle of Camrelizumab was suggested for maintenance therapy, the efficacy evaluation revealed that the tumor had greatly advanced. The patient refused to continue anti-tumor therapy and passed away from septic shock and multiple organ failure 3 months later. The patient had satisfactory efficacy and lived for a year after being diagnosed with two primary cancers. Despite the rarity of quadruple primary tumors and the lack of a conventional clinical management strategy, we postulate that germline mutations in the KRAS gene may be closely associated with the formation and development of multiple primary tumors. NGS testing is necessary for clinical management, and systemic treatment based on concurrent multiple main tumors is the key to improving prognosis.

Variations in genetics, biology, and phenotype of cutaneous disorders in skin of color - Part I: Genetic, biologic, and structural differences in skin of color

Skin of color (SOC) populations include those who identify as Black/African, Hispanic/Latinx, Asian/Pacific Islander, American Indian/Native Alaskan, Indigenous Australian, Middle Eastern, biracial/multiracial, or non-White; this list is far from exhaustive and may vary between and within cultures. Recent genetic and immunological studies have suggested that cutaneous inflammatory disorders (atopic dermatitis, psoriasis, and hidradenitis suppurativa) and malignancies (melanoma, basal cell carcinoma, and cutaneous T-cell lymphoma) may have variations in their immunophenotype among SOC. Additionally, there is growing recognition of the substantial role social determinants of health play in driving health inequalities in SOC communities. It is critically important to understand that social determinants of health often play a larger role than biologic or genetic factors attributed to "race" in health care outcomes. Herein, we describe the structural, genetic, and immunological variations and the potential implications of these variations in populations with SOC. This article underscores the importance of increasing the number of large, robust genetic studies of cutaneous disorders in SOC to create more targeted, effective therapies for this often underserved and understudied population. Part II of this CME will highlight the clinical differences in the phenotypic presentation of and the health disparities associated with the aforementioned cutaneous disorders in SOC.

Prognostic value of ulceration varies across Breslow thicknesses and clinical stages in acral melanoma: a retrospective study

BACKGROUND

Ulceration is regarded as an adverse prognostic factor and is used together with tumour thickness to subcategorize patients with cutaneous melanoma. However, the prognostic impact of ulceration in acral melanoma (AM) is controversial.

OBJECTIVES

To assess the prognostic impact of ulceration in AM and the variability across different Breslow thicknesses and clinical stages.

METHODS

A multicentre retrospective study of patients diagnosed with AM between January 2000 and December 2017. Differences in melanoma-specific survival (MSS) between patients with and without ulceration were assessed using the multivariable Cox proportional hazards model and log-rank test.

RESULTS

Among 1053 enrolled patients, 62.6% had ulceration. After a median follow-up of 61 months, patients with ulceration had a lower median MSS than those without: 66.1 months, 95% confidence interval (CI) 60.0-86.0 vs. not reached; hazard ratio 1.41, 95% CI 1.09-1.82; P = 0.012. Among patients with thin (≤ 1 mm) melanoma, the survival curves of patients with vs. without ulceration clearly separated over time (P < 0.001). No association between ulceration and MSS was observed for melanomas of thickness > 1 mm (subgroups of T2, T3 and T4; all P-values > 0.05) or patients with stage III disease (hazard ratio 1.09, 95% CI 0.71-1.68, P = 0.39).

CONCLUSIONS

Ulceration is an independent negative prognostic factor for patients with AM, but the impact varies across Breslow thicknesses and clinical stages. Ulceration has a significant effect on prognosis for patients with thin (≤ 1 mm) melanoma, but there was no association between ulceration and survival in intermediate/thick AM or stage III AM. What is already known about this topic? Ulceration status is used together with Breslow tumour thickness to subcategorize patients into different stages according to the America Joint Committee on Cancer melanoma staging system. As one distinctive subtype of cutaneous melanoma, acral melanoma (AM) is characterized by poor survival outcomes due to delayed diagnosis and a high prevalence of negative prognostic and genetic features. The prognostic impact of ulceration in AM is still controversial. What does this study add? This was the first large-scale study to assess the prognostic and staging values of ulceration in patients with AM. Ulceration has a significant effect on prognosis for patients with thin (≤1 mm) melanoma, but no association between ulceration and survival was found in intermediate/thick or stage III AM. These findings should be considered when using ulceration-based staging systems.

Actionable Mutation Profile of Sun-Protected Melanomas in South America

ABSTRACT

Melanomas that arise in sun-protected sites, including acral and oral mucosal melanomas, are likely under the control of unique, specific mechanisms that lead to mutagenesis through various pathways. In this study, we examined somatic mutations in tumors by targeted sequencing using a custom Ion Ampliseq Panel, comprising hotspots of 14 genes that are frequently mutated in solid tumors. Tumor DNA was extracted from 9 formalin fixation, paraffin-embedded sun-protected melanomas (4 primary oral mucosal melanomas and 5 acral lentiginous melanomas), and we identified mutations in the NRAS, PIK3CA, EGFR, HRAS, ERBB2, and ROS1 genes. This study reveals new actionable mutations that are potential targets in the treatment of photo-protected melanomas. Additional studies on more of these melanoma subtypes could confirm our findings and identify new mutations.

Systematic review and meta-analysis of genomic alterations in acral melanoma

Acral melanoma (AM) tumors arise on the palms, soles, fingers, toes, and nailbeds. A comprehensive systematic meta-analysis of AM genomic aberrations has not been conducted to date. A literature review was carried out to identify studies sequencing AM. Whole-genome/exome data from 181 samples were identified. Targeted panel sequencing data from MSK-IMPACT were included as a validation cohort (n = 92), and studies using targeted hot spot sequencing were also collated for BRAF (n = 26 studies), NRAS (n = 21), and KIT (n = 32). Statistical analysis indicated BRAF, NRAS, PTEN, TYRP1, and KIT as significantly mutated genes. Frequent copy-number aberrations were also found for important cancer genes, such as CDKN2A, KIT, MDM2, CCND1, CDK4, and PAK1, among others. Mapping genomic alterations within the context of the hallmarks of cancer identified four components frequently altered, including (i) sustained proliferative signaling and (ii) evading growth suppression, (iii) genome instability and mutation, and (iv) enabling replicative immortality. This analysis provides the largest analysis of genomic aberrations in AM in the literature to date and highlights pathways that may be therapeutically targetable.

Integrative molecular and clinical profiling of acral melanoma links focal amplification of 22q11.21 to metastasis

Acral melanoma, the most common melanoma subtype among non-White individuals, is associated with poor prognosis. However, its key molecular drivers remain obscure. Here, we perform integrative genomic and clinical profiling of acral melanomas from 104 patients treated in North America (n = 37) or China (n = 67). We find that recurrent, late-arising focal amplifications of cytoband 22q11.21 are a leading determinant of inferior survival, strongly associated with metastasis, and linked to downregulation of immunomodulatory genes associated with response to immune checkpoint blockade. Unexpectedly, LZTR1 - a known tumor suppressor in other cancers - is a key candidate oncogene in this cytoband. Silencing of LZTR1 in melanoma cell lines causes apoptotic cell death independent of major hotspot mutations or melanoma subtypes. Conversely, overexpression of LZTR1 in normal human melanocytes initiates processes associated with metastasis, including anchorage-independent growth, formation of spheroids, and an increase in MAPK and SRC activities. Our results provide insights into the etiology of acral melanoma and implicate LZTR1 as a key tumor promoter and therapeutic target.

More than just acral melanoma: the controversies of defining the disease

Acral melanoma (AM) is a malignant cutaneous melanocytic tumour specifically located on the palms, soles, and nail apparatus, which are areas of glabrous (hairless) skin. Acral lentiginous melanoma, a subtype of AM, represents a histopathological subtype diagnosis of cutaneous melanoma with unique morphological and structural features. Despite clear definitions, the misuse of these terms and the inconsistency in reporting the histopathological features of AM cases have become a major obstacle to the study of the disease. In this review, we discuss the epidemiology, histopathological features, prognosis, and genetic profile of AM, highlighting the differences observed when histopathological subtypes are considered. The increasing global effort to characterise AM cases from ethnically diverse populations would benefit greatly from a more consistent classification of the disease.

The tumor genetics of acral melanoma: What should a dermatologist know?

Dermatologists stand at the gateway of individualization of classification, treatment, and outcomes of acral melanoma patients. The acral melanoma genetic landscape differs in vital ways from that of other cutaneous melanomas. These differences have important implications in understanding pathogenesis, treatment, and prognosis. The selection of molecularly targeted therapy must be adapted for acral melanoma. It is also critical to recognize that tumor development is far more complex than an isolated event, reliably treated by a medication acting on a single target. Tumors exhibit intratumor genetic heterogeneity, metastasis may have different genetic or epigenetic features than primary tumors, and tumor resistance may develop because of the activation of alternative genetic pathways. Microenvironmental, immune, and epigenetic events contribute and sustain tumors in complex ways. Treatment strategies with multiple targets are required to effectively disrupt the tumor ecosystem. This review attempts to translate the current molecular understanding of acral melanoma into digestible concepts relevant to the practice of dermatology. The focus is tumor genetics defining potentially treatable cancer pathways, contextualized within the relevant pathologic and molecular features.

BRAF, KIT, and NRAS Mutations of Acral Melanoma in White Patients

OBJECTIVES

Malignant acral melanoma (AM) is relatively infrequent in white patients. Molecular investigations have returned variable results regarding the mutational pattern. We sought to describe the mutation profile and clinicopathologic features of AM.

METHODS

We investigated BRAF, KIT, and NRAS mutational status in a series of 31 AM samples from white patients.

RESULTS

Nodular melanoma was the most common histopathologic subtype (48.4%), followed by acral lentiginous melanoma (25.8%) and superficial spreading melanoma (25.8%). BRAF, KIT, and NRAS mutational rates were 12.9%, 17.2%, and 30.0%, respectively. We observed significant associations between KIT mutational status and a thinner Breslow thickness compared with wild-type (WT) status (P = .002), NRAS mutation status and younger age compared with WT. In patients presenting at least one mutation, triple-WT patients presented metastases most frequently.

CONCLUSIONS

Although these data represent preliminary results, better knowledge of tumor biology and prognosis of AM can support the clinical approach and follow-up.

Mutation profile of primary subungual melanomas in Caucasians

Background: Specific genomic profile of cutaneous melanomas is related to UVR exposure, which exerts biological and therapeutic impact. Subungual melanoma (SUM) is an exceedingly rare disease; therefore, it is not well characterized. SUM pathogenesis is not related to UVR induced DNA damage and expected to differ from other melanoma subtypes. Our study aimed to define the mutation profile of SUM in Caucasians.

Materials and Methods: Next-generation sequencing-based genomic analysis was used to identify frequently mutated loci in 50 cancer-related genes in 31 SUM primary tumors.

Results: The most abundant mutations in SUM were found in KIT – in 13% of cases and NRAS – also in 13%, while BRAF - only in 3% of cases.

Conclusions: Our findings confirmed a high frequency of KIT and NRAS mutations in SUM, as well as a low incidence of BRAF mutations. We reported novel KRAS, CTNNB1, TP53, ERBB2, and SMAD4 mutations in SUM. Our findings provide new insights into the molecular pathogenesis of SUM.

Acral lentiginous melanoma: Basic facts, biological characteristics and research perspectives of an understudied disease

Acral lentiginous melanoma is a histological subtype of cutaneous melanoma that occurs in the glabrous skin of the palms, soles and the nail unit. Although in some countries, particularly in Latin America, Africa and Asia, it represents the most frequently diagnosed subtype of the disease, it only represents a small proportion of melanoma cases in European‐descent populations, which is partially why it has not been studied to the same extent as other forms of melanoma. As a result, its unique genomic drivers remain comparatively poorly explored, as well as its causes, with current evidence supporting a UV‐independent path to tumorigenesis. In this review, we discuss current knowledge of the aetiology and diagnostic criteria of acral lentiginous melanoma, as well as its epidemiological and histopathological characteristics. We also describe what is known about the genomic landscape of this disease and review the available biological models to explore potential therapeutic targets.

The Clinicopathological and Survival Profiles Comparison Across Primary Sites in Acral Melanoma

Background

The clinicopathological and survival profiles across primary sites in acral melanoma (AM) are still controversial and unclear.

Methods

This is a multi-center retrospective study. Clinicopathological data of AM patients diagnosed between 1 January 2000 and 31 December 2017 from 6 large tertiary hospitals in China were extracted. Chi square tests were used to compare basic characteristics between primary sites of sole, palm and nail bed. Melanoma-specific survival (MSS) differences based on primary sites were compared by log-rank tests and multivariate Cox regressions were used to identify prognostic factors for MSS.

Results

In total, 1157 AM patients were included. The sole group had a more advanced initial stage, deeper Breslow thickness, higher recurrence rate and distant metastases risk (all P < 0.05). The proportion of age < 65 years and ulceration were statistically lower in nail bed and palm groups, respectively. A total of 294 patients underwent sentinel lymph node biopsy and rates of positive SLN status had no statistical difference across primary sites. Among 701 patients with genetic profiles, the mutational frequency of BRAF, C-KIT, and PDGFRA were similar except for NRAS (higher in sole group, P = 0.0102). The median MSS of sole, nail bed and palm patients were 65.0 months, 112.0 months, and not reached, respectively (log-rank P = 0.0053). In multivariate analyses, primary site, initial stage, ulceration and recurrence were the prognostic factors for MSS in overall population, but the statistical significance varied over primary sites.

Conclusions

Substantial clinicopathological and survival heterogeneities exist across different primary sites in the AM population. Sole melanoma has worse prognosis compared with palm and nail bed subtypes.

Immunohistochemical BRAF V600E Expression and Intratumor BRAF V600E Heterogeneity in Acral Melanoma: Implication in Melanoma-Specific Survival

Acral melanoma, a distinct form of cutaneous melanoma originating in the glabrous skin of the palms, soles, and nail beds, has a different genetic background from other subtypes of cutaneous melanoma. The roles of oncogenic BRAF mutations of acral melanoma in pathogenesis and patient outcomes have not been fully elucidated. We retrieved a total of 112 patients with primary acral melanoma and checked their BRAF V600E status using immunohistochemical staining of VE1 antibody. Among these cases, 21 acral melanoma samples (18.8%) showed positive BRAF V600E staining, and of those, 11 samples (9.8%) showed a heterogeneous staining pattern, with a mixture of VE1-positive and VE1-negative cells. BRAF V600E positivity was significantly associated with thicker melanoma (p = 0.0015). There was no significant difference in clinicopathological factors between homogeneous and heterogeneous VE1-positive acral melanoma. Both patients with BRAF V600E-positive acral melanoma and those with heterogeneous BRAF V600E had significantly shorter melanoma-specific survival than those with BRAF V600E-negative melanoma in Kaplan–Meier analysis (p = 0.0283 and p = 0.0065, respectively). These findings provide novel insights into the pathobiology of acral melanoma.

The clinical significance of KIT mutations in melanoma: a meta-analysis

This study aimed to evaluate the association of KIT mutations with clinicopathologic features of melanomas using a meta-analysis and to identify differences between Asian and White populations using subgroup analyses. We selected 32 studies from the literature including 5224 patients. The pooled data were combined, and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Heterogeneity and publication bias were also determined. KIT mutations were reported in 497 (9.5%) of 5224 patients with melanomas, and were associated significantly with age, clinical melanoma subtype, anatomic location, and chronic sun-damage (CSD), but not with sex, histological type, Breslow thickness, ulceration, mitotic rate, or tumor stage. The incidence of KIT mutation was significantly higher in older individuals (OR=1.296, 95% CI: 1.025-1.641; P=0.031), and showed a positive association with mucosal melanoma (OR=1.363, 95% CI: 1.094-1.697; P=0.006), acral melanoma (OR=1.374, 95% CI: 1.123-1.682; P=0.02), and CSD (OR=1.880, 95% CI: 1.127-3.136; P=0.016), but a negative relationship with melanomas arising in non-CSD skin (OR=0.562, 95% CI: 0.392-0.805; P=0.002). The frequency of KIT mutations was associated negatively with melanomas located on the extremities. KIT mutations, which are critical in the genetic pathogenesis of melanomas, define a unique subtype of melanoma associated closely with older age, and acral, mucosal, or CSD sites, but not associated with any histological features or tumor stage. Although the KIT mutation rate is higher in White than Asian populations, no significant difference in clinical association with KIT mutations was detected between the two groups.

Genetic Alterations in Primary Acral Melanoma and Acral Melanocytic Nevus in Korea: Common Mutated Genes Show Distinct Cytomorphological Features

Acral melanoma occurring on the palms, soles, and nails is the most common subtype of cutaneous melanoma in Asians. Genetic alterations in acral melanoma and acral melanocytic nevus are not well known. We performed next-generation sequencing and evaluated the correlations between genetic information and the clinicopathologic characteristics from 85 Korean patients with acral melanocytic neoplasms. Of the 64 patients with acral melanoma, most had lesions at the T2 stage or higher, and the heel was the most common anatomical site of melanoma (n = 34 [53.1%]). The five most common mutations were BRAF (22 [34.4%]), NRAS (14, [21.9%]), NF1 (11, [17.2%]), GNAQ (12, [17.2%]), and KIT (7, [10.9%]). In the 21 acral melanocytic nevi, those five gene mutations were also common. Copy number variations were also frequently detected in 75% of acral melanomas and 47.6% of acral melanocytic nevi, and amplification was more common than deletion in both lesions. BRAF mutation was associated with round epithelioid cells and NRAS and NF1 mutations with bizarre cells. NF1 and GNAQ mutations showed elongated and spindle cells with prominent dendrites in acral melanomas. KIT mutations were common in amelanotic acral melanoma. This study suggests that common mutated genes are associated with distinct cytomorphological features in acral melanocytic lesions.

Acral melanoma: correlating the clinical presentation to the mutational status

Acral lentiginous melanoma (ALM) is the most common type of malignant melanoma (MM) in Asians, Afro-Americans and Middle-Easterners. It represents 1.5-10% of all MM cases, being the most common histological type of MM arising on palms, soles and nail apparatus, which is more generically defined as acral MM. To date no risk factors have been officially established, however a history of trauma may be involved in the pathogenesis of acral MM. This shows heterogeneous clinical features and frequently presents with advanced stage and aggressive behavior, often as a result of misdiagnosis or delayed identification. Dermoscopy is helpful for an early diagnosis of ALM: the most characteristic dermoscopic patterns are the parallel ridge and the irregular diffuse pigmentation. On histopathology ALM displays a lentiginous growth pattern, with melanocytes arranged as solitary units along the basilar epidermis, without notable pagetoid growth in the early stage. Not all acral MMs present a lentiginous pattern: superficial spreading melanoma and nodular melanoma patterns are also possible. Novel studies investigating the biologic characteristics of acral MM reported variable results: the overall mutational rates ranged respectively between 8.5% and 23% for KIT, between 3.6% and 33.3% for BRAF and between 3% and 47% for NRAS in ALMs. Increasing attention has been recently given to other genes, such as telomerase reverse transcriptase, platelet-derived growth factor receptor alfa and cyclin D1. Larger molecular investigations urge to describe the molecular profile of acral MM, to allow the development of specific targeted therapies.