Evolving Treatment Approaches to Mucosal Melanoma

Clinical Characteristics and Special Considerations in the Management of Rare Melanoma Subtypes

Rare histologic subtypes of melanoma, including acral, mucosal, uveal, and desmoplastic melanomas, only make up 5% of all diagnosed melanomas and are often underrepresented in large, randomized trials. Recent advancements in systemic therapy have shown marked improvement in pathologic response rates, improving progression-free and overall survival among cutaneous melanoma patients, but there are limited data to demonstrate improved survival among rarer subtypes of melanoma. Acral melanoma has a poor response to immunotherapy and is associated with worse survival. Mucosal melanoma has a large variability in its presentation, a poor prognosis, and a low mutational burden. Uveal melanoma is associated with a high rate of liver metastasis; recent adoption of infusion and perfusion therapies has demonstrated improved survival among these patients. Desmoplastic melanoma, a high-risk cutaneous melanoma, is associated with high locoregional recurrence rates and mutational burden, suggesting this melanoma may have enhanced response to immunotherapy. While these variants of melanoma represent distinct disease entities, this review highlights the clinicopathologic characteristics and treatment recommendations for each of these rare melanomas and highlights the utility of modern therapies for each of them.

Primary non-cutaneous melanomas of the head and neck: Case series and review of the literature

Primary non-cutaneous melanoma is a rare type of melanoma that occurs mostly on mucosal surfaces. The head and neck region is the most common site for these melanomas. The following cases described herein include patients diagnosed with primary non-cutaneous melanomas. The locations included the parotid gland (one case), the submandibular gland (one case), and the nasal cavity and paranasal sinuses (three cases). Among these patients, one patient developed lymph node metastasis and one patient had distant metastasis. Treatment included endoscopic surgery (one case), endoscopic surgery with adjuvant radiotherapy (one case), open surgery (one case), and palliative chemotherapy (one case). One patient refused to receive treatment. After treatment, one patient had local recurrence. A local and distant recurrence was noted in one case. This report aims to describe clinical features, treatment options, and prognosis of primary non-cutaneous melanomas of the head and neck.

Comparative Epigenetic Profiling Reveals Distinct Features of Mucosal Melanomas Associated with Immune Cell Infiltration and Their Clinical Implications

Mucosal melanoma exhibits limited responsiveness to anti-PD-1 therapy. However, a subgroup of mucosal melanomas, particularly those situated at specific anatomic sites like primary malignant melanoma of the esophagus (PMME), display remarkable sensitivity to anti-PD-1 treatment. The underlying mechanisms driving this superior response and the DNA methylation patterns in mucosal melanoma have not been thoroughly investigated. We collected tumor samples from 50 patients with mucosal melanoma, including 31 PMME and 19 non-esophageal mucosal melanoma (NEMM). Targeted bisulfite sequencing was conducted to characterize the DNA methylation landscape of mucosal melanoma and explore the epigenetic profiling differences between PMME and NEMM. Bulk RNA sequencing and multiplex immunofluorescence staining were performed to confirm the impact of methylation on gene expression and immune microenvironment. Our analysis revealed distinct epigenetic signatures that distinguish mucosal melanomas of different origins. Notably, PMME exhibited distinct epigenetic profiling characterized by a global hypermethylation alteration compared with NEMM. The prognostic model based on the methylation scores of a 7-DMR panel could effectively predict the overall survival of patients with PMME and potentially serve as a prognostic factor. PMME displayed a substantial enrichment of immune-activating cells in contrast to NEMM. Furthermore, we observed hypermethylation of the TERT promoter in PMME, which correlated with heightened CD8+ T-cell infiltration, and patients with hypermethylated TERT were likely to have improved responses to immunotherapy. Our results indicated that PMME shows a distinct methylation landscape compared with NEMM, and the epigenetic status of TERT might be used to estimate prognosis and direct anti-PD-1 treatment for mucosal melanoma.

SIGNIFICANCE

This study investigated the intricate epigenetic factor of mucosal melanomas contributed to the differential immune checkpoint inhibitor response, and found that PMME exhibited a global hypermethylation pattern and lower gene expression in comparison to NEMM. TERT hypermethylation may contribute to the favorable responses observed in patients with mucosal melanoma undergoing immunotherapy.

Mucosal Melanoma Clinical Management and Prognostic Implications: A Retrospective Cohort Study

Mucosal melanoma (MM) is an uncommon melanoma subtype affecting mucosal surfaces of the head and neck, anorectal region, and vulvovaginal area. We aimed to present our experience at a tertiary-level hospital regarding MM diagnosis, management, monitoring of progression, mutations, and outcome predictors. We performed a registry-based cohort study including MM cases diagnosed from 2012 to 2022 and retrospectively characterized somatic mutations on BRAF, NRAS and c-KIT. We employed Kaplan-Meier curves, log-rank tests, and Cox regression analysis to explore prognostic factors and survival outcomes in a cohort of 35 patients, mainly women (63%) with a median age of 70 years. Predominantly, MM occurred in the vulvovaginal region (48.6%). At diagnosis, 28.6% had lymph node involvement, and 31.4% also had distant metastasis. Mutations in BRAF and c-KIT were identified in 3/35 (9%) and 2/6 patients (33%), respectively. Surgery was performed in 71.4% of patients, and most received systemic treatment (65.7%). Lower disease stage, thinner Breslow depth, and surgical resection were associated with improved overall survival. Notably, age, sex, radiotherapy, and BRAF mutant status did not affect survival. Standard management typically involves immunotherapy. Cases with BRAF or c-KIT mutations may be considered for targeted therapies. Unfortunately, MM prognosis remains unfavorable, with a less than 50% survival rate at 2 years.

A human mucosal melanoma organoid platform for modeling tumor heterogeneity and exploring immunotherapy combination options

Mucosal melanoma (MM), an aggressive rare subtype of melanoma, is distinct from cutaneous melanoma and has poor prognoses. We addressed the lack of cell models for MM by establishing 30 organoids of human oral MM (OMM), which retained major histopathological and functional features of parental tumors. Organoid groups derived from chronologically or intratumorally distinct lesions within the same individual displayed heterogeneous genetics, expression profiles, and drug responses, indicating rapid tumor evolution and poor clinical response. Furthermore, transcriptome analysis revealed receptor tyrosine kinases (RTKs) signaling, particularly NGFR, a nerve growth factor receptor, was significantly up-regulated in OMMs and organoids from patients resistant to anti-programmed cell death protein 1 (anti-PD-1) therapy. Combining anti-PD-1 with anlotinib (a phase 2 multitarget RTK inhibitor for OMM) or NGFR knockdown enhanced the effective activity of immune cells in organoid-immune cell coculture systems. Together, our study suggested that OMM organoids serve as faithful models for exploring tumor evolution and immunotherapy combination strategies.

Clinical significance of genetic profiling based on different anatomic sites in patients with mucosal melanoma who received or did not receive immune checkpoint inhibitors

BACKGROUND

To date, data on the efficacy of targeted therapies for mucosal melanoma (MM) are limited. In this study, we analyzed genetic alterations according to the primary site of origin, which could provide clues for targeted therapy for MM.

METHODS

We conducted a retrospective cohort study of 112 patients with MM. Targeted sequencing was performed to analyze genetic aberrations. Kaplan-Meier analysis was conducted with the log-rank test to compare the significance among subgroups.

RESULTS

In total, 112 patients with MM were included according to the anatomic sites: 38 (33.9%) in the head and neck, 22 (19.6%) in the genitourinary tract, 21 (18.8%) in the anorectum, 19 (17.0%) in the esophagus, 10 (8.9%) in the uvea, and 2 (1.8%) in the small bowel. The most significantly mutated genes included BRAF (17%), KIT (15%), RAS (15%), TP53 (13%), NF1 (12%), SF3B1 (11%), GNA11 (7%), GNAQ (5%), and FBXW7 (4%). A large number of chromosomal structural variants was found. The anatomic sites of esophagus and small bowel were independent risk factors for progression-free survival (PFS, hazard ratio [HR] 4.78, 95% confidence interval [CI] 2.42-9.45, P < 0.0001) and overall survival (OS, HR 5.26, 95% CI 2.51-11.03, P < 0.0001). Casitas B-lineage lymphoma (CBL) mutants showed significantly poorer PFS and OS. In contrast, MM patients who received immune checkpoint inhibitors (ICIs) had a significantly more favorable OS (HR 0.39, 95% CI 0.20-0.75, P = 0.008).

CONCLUSIONS

Our findings reveal the genetic features of patients with MM, mainly across six anatomic sites, offering a potential avenue for targeted therapies.

Primary Mucosal Melanoma of the Lip With GNA11 Mutation in a 23-Year-Old Pregnant Woman

Mucosal melanoma represents a small proportion of all melanoma cases and is associated with a worse prognosis. Primary malignant melanoma of the lip (PMML) is far less common, and only a few cases have been reported since 1997, most commonly in China, Japan, Uganda, and India. Most of these cases have been associated with the gene C-KIT. As a result, treatment guidelines surrounding mucosal melanoma are unclear, especially in complicated populations such as pregnant women. Mutations in theGNAQ and GNA11 genes have been found to be associated with uveal melanoma, while they are rarely associated with mucosal melanoma. We present the case of a 23-year-old pregnant woman who was found to have likely primary malignant melanoma of the lip that metastasized to the left jaw, neck, breast, lungs, and ovaries and was found to be positive for both the BRAF-MLL3 and GNA11 mutation.

Current Trends in Mucosal Melanomas: An Overview

Primary mucosal melanomas (MMs) are uncommon tumors originating from melanocytes located in the mucous membranes at various anatomic sites within the body. MM significantly differs from cutaneous melanoma (CM) regarding epidemiology, genetic profile, clinical presentation, and response to therapies. Despite these differences, that have important implications for both disease diagnosis and prognosis, MMs are usually treated in the same way as CM but exhibit a lower response rate to immunotherapy leading to a poorer survival rate. Furthermore, a high inter-patient variability can be observed in relation to therapeutic response. Recently, novel "omics" techniques have evidenced that MM lesions have different genomic, molecular, and metabolic landscapes as compared with CM lesions, thus explaining the heterogeneity of the response. Such specific molecular aspects might be useful to identify new biomarkers aimed at improving the diagnosis and selection of MM patients who could benefit from immunotherapy or targeted therapy. In this review, we have focused on relevant molecular and clinical advancements for the different MM subtypes in order to describe the updated knowledge relating to main diagnostic, clinical, and therapeutic implications as well as to provide hints on likely future directions.

Neoadjuvant checkpoint inhibitor immunotherapy for resectable mucosal melanoma

Background

Neoadjuvant checkpoint inhibition (CPI) has recently demonstrated impressive outcomes in patients with stage 3 cutaneous melanoma. However, the safety, efficacy, and outcome of neoadjuvant CPI in patients with mucosal melanoma (MM) are not well studied as MM is a rare melanoma subtype. CPI such as combination nivolumab and ipilimumab achieves response rates of 37-43% in unresectable or metastatic MM but there is limited data regarding the efficacy of these agents in the preoperative setting. We hypothesize that neoadjuvant CPI is a safe and feasible approach for patients with resectable MM.

Method

Under an institutionally approved protocol, we identified adult MM patients with resectable disease who received neoadjuvant anti-PD1 +/- anti-CTLA4 between 2015 to 2019 at our institution. Clinical information include age, gender, presence of nodal involvement or satellitosis, functional status, pre-treatment LDH, tumor mutation status, and treatment data was collected. Outcomes include event free survival (EFS), overall survival (OS), objective response rate (ORR), pathologic response rate (PRR), and grade ≥3 toxicities.

Results

We identified 36 patients. Median age was 62; 58% were female. Seventy-eight percent of patients received anti-PD1 + anti-CTLA4. Node positive disease or satellite lesions was present at the time of treatment initiation in 47% of patients. Primary sites of disease were anorectal (53%), urogenital (25%), head and neck (17%), and esophageal (6%). A minority of patients did not undergo surgery due to complete response (n=3, 8%) and disease progression (n=6, 17%), respectively. With a median follow up of 37.9 months, the median EFS was 9.2 months with 3-year EFS rate of 29%. Median OS had not been reached and 3-year OS rate was 55%. ORR was 47% and PRR was 35%. EFS was significantly higher for patients with objective response and for patients with pathologic response. OS was significantly higher for patients with pathologic response. Grade 3 toxicities were reported in 39% of patients.

Conclusion

Neoadjuvant CPI for resectable MM is a feasible approach with signs of efficacy and an acceptable safety profile. As there is currently no standard approach for resectable MM, this study supports further investigations using neoadjuvant therapy for these patients.