Tumor infiltrating lymphocytes in acral lentiginous melanoma: a study of a large cohort of cases from Latin America

Baseline Serum neutrophil-to-lymphocyte ratio in acral melanoma compared with nonacral melanoma and its prognostic significance

BACKGROUND

Acral lentiginous melanoma (ALM), a cutaneous melanoma subtype, exhibits a poorer prognosis than nonacral cutaneous melanoma (NACM). The neutrophil-to-lymphocyte ratio (NLR) is emerging as a prognostic indicator across diverse cancers.

OBJECTIVE

We explored the baseline NLR disparities between ALM and NACM, and the NLR's prognostic significance in patients with ALM.

METHODS

We reviewed records of patients with ALM and NACM diagnosed between 1997 and 2022, analyzing medical data.

RESULTS

Among 327 and 159 patients with ALM and NACM, respectively, baseline NLR varied based on distinct clinicopathologic factors between ALM and NACM. In stage 3 to 4 melanomas, the median NLR for ALM (2.18; IQR, 1.70-3.08) significantly surpassed NACM (1.74; IQR, 1.33-2.53) (P = .029). In patients with ALM, high NLR (hazard ratio, 1.64; 95% CI, 1.02-2.66; P = .043) was independently correlated with poor progression-free survival when adjusting for ulceration, Breslow thickness of ≥2 mm, and nodal invasion.

LIMITATIONS

Single-center, retrospective design.

CONCLUSION

Advanced-stage ALM exhibited a significantly higher baseline NLR compared with that of NACM. Evaluating baseline NLR could provide valuable prognostic insights for patients with ALM.

Clinical and translational attributes of immune-related adverse events

With immune checkpoint inhibitors (ICIs) becoming the mainstay of treatment for many cancers, managing their immune-related adverse events (irAEs) has become an important part of oncological care. This Review covers the clinical presentation of irAEs and crucial aspects of reversibility, fatality and long-term sequelae, with special attention to irAEs in specific patient populations, such as those with autoimmune diseases. In addition, the genetic basis of irAEs, along with cellular and humoral responses to ICI therapy, are discussed. Detrimental effects of empirically used high-dose steroids and second-line immunosuppression, including impaired ICI effectiveness, call for more tailored irAE-treatment strategies. We discuss open therapeutic challenges and propose potential avenues to accelerate personalized management strategies and optimize outcomes.

Association of NRAS mutations and tertiary lymphoid structure formation with clinical outcomes of adjuvant PD-1 inhibitors for acral melanoma

OBJECTIVES

This study evaluates the efficacy of programmed death-1 (PD-1) inhibitors as adjuvant therapy for acral melanoma (AM) and the predictive value of genetic mutations and tertiary lymphoid structures (TLSs).

METHODS AND RESULTS

A single-center retrospective longitudinal cohort study was conducted between October 1, 2018, and September 31, 2022. Patients with stages II-III completely resected AM were treated with at least two doses of adjuvant PD-1 inhibitors. A total of 44 participants were included in the final analysis, of which 41 patients with stage III. The median follow-up time, median relapse-free survival (RFS), and median distance metastasis-free survival (DMFS) for all patients were 18.4 months, 21.6 months, and 30.6 months, respectively. 21 (47.7%) and 20 (45.5%) patients were intravenously administered pembrolizumab and toripalimab, respectively. There were no significant differences in RFS (24.4 months vs. 18.9 months, p = 0.432) or DMFS (30.6 months vs. not reached, p = 0.865) between the pembrolizumab and toripalimab groups, respectively. The median DMFS (41.1 months vs. 9.0 months, p < 0.001) in the wild-type NRAS group was significantly longer than that in the NRAS mutation group. Overall, different levels of TLSs infiltration did not significantly affect patient survival. Only three people discontinued treatment due to adverse events. No treatment-related death occurred during the study period.

CONCLUSION

Our study suggests that adjuvant toripalimab and pembrolizumab therapy have comparable efficacies in patients with AM and are both well tolerated. Adjuvant monotherapy with PD-1 inhibitors may not be appropriate for AM with NRAS mutations.

Impact of clinical and histopathological characteristics on the disease-free survival of stage I-II acral melanoma patients

BACKGROUND

Acral melanoma is rare and associated with a worse prognosis compared to cutaneous melanoma in other locations. Despite this, few studies have focused on the prognosis of acral melanoma, particularly in patients with initial clinical stage. The aim of this study was to assess the impact of clinical and histopathological characteristics on the disease-free survival (DFS) of stage I-II patients.

METHODS

We analyzed 154 stage I-II acral melanoma cases, all of whom underwent a review of the histopathological and clinical parameters. Patients were divided into groups based on the presence or absence of disease recurrence within 5 years. We used Cox proportional regression to analyze independent risk factors and computed DFS curves using the Kaplan-Meier method.

RESULTS

Within 5 years, 27.9% of patients experienced disease recurrence, with 90.4% occurring during the first 3 years. Univariate and multivariate analyses did not identify any clinical parameters with a significant influence on DFS. The DFS rate at 5 years was 72.7%. The median duration of disease recurrence after the initial diagnosis was 21 months. However, Breslow thickness, presence of ulceration, >3 mitosis/mm2 , presence of tumor-infiltrating lymphocytes (TIL), and perineural invasion were significantly associated with a decrease in time to first recurrence.

CONCLUSIONS

Despite the favorable prognosis of stage I-II acral melanoma compared with advance stage, clinical and histopathological characteristics can impact prognosis. In addition to Breslow thickness and ulceration, attention should be paid to mitotic rate, presence of TIL, and perineural invasion to optimize follow-up of acral melanoma patients diagnosed in the initial clinical stage.

Cutaneous immune-related adverse events from immune checkpoint inhibitor therapy: Moving beyond "maculopapular rash"

Uncoupling toxicity from therapeutic effect lies at the foundation of the current state of the field of cutaneous immune-related adverse events to immune checkpoint inhibitor therapy. This will be achieved through understanding the drivers of toxicity, tumor response, and resistance via large, well-powered population-level studies, institutional cohort data, and cellular-level data. Increasing diagnostic specificity through the application of consensus disease definitions has the power to improve clinical care and each approach to research. Cutaneous immune-related adverse events are associated with increased survival, and their treatment must invoke the maintenance of a delicate balance between immunosuppression, anti-tumor effect of immune checkpoint inhibitor therapy, and quality of life. The multidisciplinary care of cancer patients with adverse events is critical to optimizing clinical and translational research outcomes and, as such, dermatologists are vital to moving the study of cutaneous adverse events forward.

Apatinib combined with camrelizumab in advanced acral melanoma patients: An open-label, single-arm phase 2 trial

BACKGROUND

At present, immune monotherapy and combination therapy has not shown satisfactory effects on acral melanoma, and still no standard treatment is available for advanced acral melanoma. Here, a phase II trial was performed to explore the safety and efficacy of apatinib combined with camrelizumab in advanced acral melanoma patients as first-line therapy (NCT03955354).

METHODS

Patients with pathologically confirmed, locally unresectable or metastatic treatment native acral melanoma received 250 mg apatinib once daily and camrelizumab 200 mg once every two weeks intravenously every 28-day cycle. The primary end-point was objective response rate and the secondary end-points were disease control rate, overall survival, progression-free survival and safety.

RESULTS

Thirty patients were recruited between January 2015 and January 2022. Among them, 21 (70.0%) had stage IV, and a median tumour burden was 50 mm (range: 11-187). Objective response rate was 24.1%, and 7 of 29 patients had an anti-tumour response, including partial response (n = 5) and complete response (n = 2). Disease control rate was 82.8%, median progression-free survival was 7.39 months (confidence interval: 3.65-9.92), and median overall survival was 13.4 months (confidence interval: 1.9-25.0). Grade 3-4 treatment-related toxicity (grade 3 50.5%; grade 4 3.3%) included transaminase elevations, proteinuria, leukocytopenia, vomiting, diarrhea and drug-induced liver injury. No treatment-related mortality occurred. The mutations of TTN, MUC16, VPS13D, ALPK2 and SCUBE1 showed significant alterations with survival outcome.

CONCLUSIONS

Apatinib combined with camrelizumab showed manageable safety profile and reasonable anti-tumour activity in advanced acral melanoma patients as first-line therapy.

Acral Melanoma Is Infiltrated with cDC1s and Functional Exhausted CD8 T Cells Similar to the Cutaneous Melanoma of Sun-Exposed Skin

Acral melanoma (AM) is the most common melanoma in non-Caucasian populations, yet it remains largely understudied. As AM lacks the UV-radiation mutational signatures that characterize other cutaneous melanomas, it is considered devoid of immunogenicity and is rarely included in clinical trials assessing novel immunotherapeutic regimes aiming to recover the antitumor function of immune cells. We studied a Mexican cohort of melanoma patients from the Mexican Institute of Social Security (IMSS) (n = 38) and found an overrepresentation of AM (73.9%). We developed a multiparametric immunofluorescence technique coupled with a machine learning image analysis to evaluate the presence of conventional type 1 dendritic cells (cDC1) and CD8 T cells in the stroma of melanoma, two of the most relevant immune cell types for antitumor responses. We observed that both cell types infiltrate AM at similar and even higher levels than other cutaneous melanomas. Both melanoma types harbored programmed cell death protein 1 (PD-1⁺) CD8 T cells and PD-1 ligand (PD-L1⁺) cDC1s. Despite this, CD8 T cells appeared to preserve their effector function and expanding capacity as they expressed interferon-γ (IFN-γ) and KI-67. The density of cDC1s and CD8 T cells significantly decreased in advanced stage III and IV melanomas, supporting these cells' capacity to control tumor progression. These data also argue that AM could respond to anti-PD-1-PD-L1 immunotherapy.

Advanced Acral Melanoma Therapies: Current Status and Future Directions

Melanoma is one of the deadliest malignancies. Its incidence has been significantly increasing in most countries in recent decades. Acral melanoma (AM), a peculiar subgroup of melanoma occurring on the palms, soles, and nails, is the main subtype of melanoma in people of color and is extremely rare in Caucasians. Although great progress has been made in melanoma treatment in recent years, patients with AM have shown limited benefit from current therapies and thus consequently have worse overall survival rates. Achieving durable therapeutic responses in this high-risk melanoma subtype represents one of the greatest challenges in the field. The frequency of BRAF mutations in AM is much lower than that in cutaneous melanoma, which prevents most AM patients from receiving treatment with BRAF inhibitors. However, AM has more frequent mutations such as KIT and CDK4/6, so targeted therapy may still improve the survival of some AM patients in the future. AM may be less susceptible to immune checkpoint inhibitors because of the poor immunogenicity. Therefore, how to enhance the immune response to the tumor cells may be the key to the application of immune checkpoint inhibitors in advanced AM. Anti-angiogenic drugs, albumin paclitaxel, or interferons are thought to enhance the effectiveness of immune checkpoint inhibitors. Combination therapies based on the backbone of PD-1 are more likely to provide greater clinical benefits. Understanding the molecular landscapes and immune microenvironment of AM will help optimize our combinatory strategies.

Risk factors for lymphatic and hematogenous metastasis after diagnosis of cutaneous Melanoma in Taiwan

BACKGROUND

Risk factors of lymphatic and hematogenous metastasis in cutaneous melanoma remained unclear in Asian population. This study aimed to identify clinical and histopathological factors to predict metastatic pathways in cutaneous melanoma in Taiwan.

METHODS

A total of 247 patients diagnosed as stage I and II melanoma, followed at National Taiwan University Hospital were included in this retrospective study from 1980 to 2020. Kaplan-Meier curves and Cox proportional hazards regression were utilized to identify risk factors.

RESULTS

During a median follow-up of 143 months, 48 (19.4%) and 62 (25.1%) patients developed lymphatic and hematogenous metastasis respectively. In the univariate analysis, age> 70 years, greater Breslow thickness, ulceration, neurotropism, and NRAS mutation were significant risk factors for lymphatic metastasis in all subtypes of melanoma. Age >70 years, head and neck location, thickness, ulceration, higher mitotic rate, neurotropism, and NRAS mutation were significant predictors of hematogenous metastasis in all subtypes. In the multivariate analysis, greater thickness (HR for 2.0-4.0 mm, 4.5; p = .009 and HR for >4.0 mm, 5.7; p = .003) retained its significance as an independent risk factor for lymphatic metastasis in all subtypes of melanoma. Thickness (HR for >4.0 mm, 5.7; p < .001) and ulceration (HR, 2.5; p = .001) were independent risk factors for hematogenous metastasis.

CONCLUSION

Risk factors of metastasis not only differ between lymphatic and hematogenous pathways, but also differ between ethnics and melanoma subtypes. Better understanding the behavior of cutaneous melanoma may help guide further treatments and follow-up plans.

Benefit and toxicity of programmed death-1 blockade vary by ethnicity in patients with advanced melanoma: an international multicentre observational study

BACKGROUND

Programmed cell death receptor-1 (PD-1) monotherapy is a standard treatment for advanced cutaneous melanoma, but its efficacy and toxicity are defined in white populations and remain poorly characterized in other ethnic groups, such as East Asian, Hispanic and African.

OBJECTIVES

To determine the efficacy and toxicity of PD-1 monotherapy in different ethnic groups.

METHODS

Clinical data for patients with unresectable or advanced melanoma treated with anti-PD-1 monotherapy between 2009 and 2019 were collected retrospectively from five independent institutions in the USA, Australia and China. Tumour response, survival and immune-related adverse events (irAEs) were compared by ethnicity (white vs. East Asian/Hispanic/African) across different melanoma subtypes: nonacral cutaneous (NAC)/unknown primary (UP) and acral/mucosal/uveal.

RESULTS

In total, 1135 patients were included. White patients had significantly higher objective response rate (ORR) [54%, 95% confidence interval (CI) 50-57% vs. 20%, 95% CI 13-28%; adjusted P < 0·001] and longer progression-free survival (14·2 months, 95% CI 10·7-20·3 vs. 5·4 months, 95% CI 4·5-7·0; adjusted P < 0·001) than East Asian, Hispanic and African patients in the NAC and UP subtypes. White ethnicity remained independently associated with a higher ORR (odds ratio 4·10, 95% CI 2·48-6·81; adjusted P < 0·001) and longer PFS (hazard ratio 0·58, 95% CI 0·46-0·74; adjusted P < 0·001) in multivariate analyses after adjustment for age, sex, primary anatomical location, metastasis stage, baseline lactate dehydrogenase level, mutational status and prior systemic treatment. White and East Asian/Hispanic/African patients shared similar ORR and progression-free survival in acral/mucosal/uveal melanomas. Similar melanoma-subtype-specific ethnic discrepancies were observed in complete response rate and overall survival. White patients had higher rates of gastrointestinal irAEs but lower rates of endocrine, liver and other rare types of irAEs. These differences in irAEs by ethnicity were not attributable to varying melanoma subtypes.

CONCLUSIONS

Ethnic discrepancy in clinical benefit is specific to melanoma subtype, and East Asian, Hispanic and African patients with NAC and UP melanomas have poorer clinical benefits than previously recognized. The ethnic discrepancy in toxicity observed across different melanoma subtypes warrants an ethnicity-based irAE surveillance strategy. More research is needed to elucidate the molecular and immunological determinants of these differences. What is already known about this topic? There is a great difference in response to immunotherapy between different subtypes of melanoma (cutaneous, mucosal, acral and uveal) in patients with advanced disease. What does this study add? Our data show for the first time that there are differences between different ethnic groups in terms of both response and toxicity to immunotherapy beyond the well-appreciated discrepancies due to melanoma subtype.

Clinical features, molecular pathology, and immune microenvironmental characteristics of acral melanoma

Acral melanoma (AM) has unique biology as an aggressive subtype of melanoma. It is a common subtype of melanoma in races with darker skin tones usually diagnosed at a later stage, thereby presenting a worse prognosis compared to cutaneous melanoma. The pathogenesis of acral melanoma differs from cutaneous melanoma, and trauma promotes its development. Compared to cutaneous melanomas, acral melanomas have a significantly lighter mutational burden with more copy number variants. Most acral melanomas are classified as triple wild-type. In contrast to cutaneous melanomas, acral melanomas have a suppressive immune microenvironment. Herein, we reviewed the clinical features, genetic variants, and immune microenvironmental characteristics of limbic melanomas to summarise their unique features.

Adjuvant Anti-PD-1 Antibody Therapy for Advanced Melanoma: A Multicentre Study of 78 Japanese Cases

Anti-PD-1 antibodies (Abs) are among the optimal adjuvant therapies for melanoma at high risk of recurrence, especially BRAF wild-type melanoma, but the anti-tumour effects of anti-PD-1 Abs in the adjuvant setting for acral melanoma have not been evaluated previously. The aim of this study was to analyse the efficacy and safety profiles of anti-PD-1 Ab monotherapy in the adjuvant setting in an Asian population including a high ratio of acral melanoma. The efficacy and safety profiles of anti-PD-1 Ab monotherapy in the adjuvant setting were retrospectively analysed in 78 Japanese patients with advanced melanoma, including 31 cases (40%) of acral melanoma. Overall relapse-free survival was 60.3% (47 of 78 cases, 95% confidence interval (CI) 49.2-70.4%), and 39.7% of patients (31 of 78 patients, 95% CI 29.6-50.8%) relapsed during the adjuvant PD-1 Ab treatment. Six cases (7.9%) discontinued the protocol due to serious adverse events. One case (1.3%) discontinued the protocol due to trauma. The relapse-free survival of acral melanoma was 25.8%, whereas that of high cumulative sun damage was 60.0%, and that of low cumulative sun damage was 57.1%. The acral type had a significantly lower 12-month relapse-free survival than other cutaneous types (p = 0.029). The acral type appeared to be an independent prognostic factor on multivariate analysis (p = 0.015). Adverse events due to anti-PD-1 antibody were observed in 37.1% overall. The results of this study suggest that anti-PD-1 Ab therapy in the adjuvant setting is less effective for acral melanoma than for other cutaneous types.

Efficacy of anti-PD-1 and ipilimumab alone or in combination in acral melanoma

BACKGROUND

Acral melanoma is a rare melanoma subtype with poor prognosis. Importantly, these patients were not identified as a specific subgroup in the landmark melanoma trials involving ipilimumab and the anti-programmed cell death protein-1 (PD-1) agents nivolumab and pembrolizumab. There is therefore an absence of prospective clinical trial evidence regarding the efficacy of checkpoint inhibitors (CPIs) in this population. Acral melanoma has lower tumor mutation burden (TMB) than other cutaneous sites, and primary site is associated with differences in TMB. However the impact of this on the effectiveness of immune CPIs is unknown. We examined the efficacy of CPIs in acral melanoma, including by primary site.

METHODS

Patients with unresectable stage III/IV acral melanoma treated with CPI (anti-PD-1 and/or ipilimumab) were studied. Multivariable logistic and Cox regression analyses were conducted. Primary outcome was objective response rate (ORR); secondary outcomes were progression-free survival (PFS) and overall survival (OS).

RESULTS

In total, 325 patients were included: 234 (72%) plantar, 69 (21%) subungual and 22 (7%) palmar primary sites. First CPI included: 184 (57%) anti-PD-1, 59 (18%) anti-PD-1/ipilimumab combination and 82 (25%) ipilimumab. ORR was significantly higher with initial anti-PD-1/ipilimumab compared with anti-PD-1 (43% vs 26%, HR 2.14, p=0.0004) and significantly lower with ipilimumab (15% vs 26%, HR 0.49, p=0.0016). Landmark PFS at 1 year was highest for anti-PD-1/ipilimumab at 34% (95% CI 24% to 49%), compared with 26% (95% CI 20% to 33%) with anti-PD-1 and 10% (95% CI 5% to 19%) with ipilimumab. Despite a trend for increased PFS, anti-PD-1/ipilimumab combination did not significantly improve PFS (HR 0.85, p=0.35) or OS over anti-PD-1 (HR 1.30, p=0.16), potentially due to subsequent therapies and high rates of acquired resistance. No outcome differences were found between primary sites.

CONCLUSION

While the ORR to anti-PD-1/ipilimumab was significantly higher than anti-PD-1 and PFS numerically higher, in this retrospective cohort this benefit did not translate to improved OS. Future trials should specifically include patients with acral melanoma, to help determine the optimal management of this important melanoma subtype.

Cutaneous melanoma incidence, mortality, and survival in Manizales, Colombia: a population-based study

OBJECTIVE

We estimated the cutaneous melanoma (CM) incidence, mortality, and survival in Manizales, Colombia to establish predictors for survival.

METHODS

This analytical cohort study used CM incident cases during 2006 to 2015 in the Manizales Cancer Registry (n = 132). Incidence and mortality rates were standardized using the direct method. Patients were followed up until 30 November 2020. Cause-specific survival was calculated using the Kaplan-Meier method for variables of interest, with the log-rank test for differences. Cox multivariate regression models were fitted.

RESULTS

Incidence (per 100,000) increased from 1.6 to 3.0 in men and 2.6 to 2.8 in women during 2006-2010 to 2011-2015, respectively. Mortality was low and stable. Five-year survival was 68.7%, with significant differences according to age (hazard ratio [HR] >70 vs. ≤70 years: 3.37); histological subtype (HR for melanoma not otherwise specified and HR for nodular melanoma vs lentigo malignant melanoma and superficial spreading melanoma: 17.39 and 10.16, respectively); and clinical stage (HR stages III-IV vs. stages I-II: 5.94).

CONCLUSION

CM is characterized by increasing incidence and unfavorable prognosis, particularly in patients aged >70 years, with melanoma not otherwise specified and nodular melanoma, and advanced stages. Promoting photoprotection and early detection and management of suspicious skin lesions is crucial.

Acral lentiginous melanoma histotype predicts outcome in clinical stage I-II melanoma patients: an International multicenter study

BACKGROUND

In the American Joint Committee on Cancer (AJCC) classification, acral lentiginous melanoma (ALM) histotype ALM is not included as an independent prognostic factor; in small series its negative prognostic impact on disease-free survival (DFS) and overall survival (OS) has been linked to the greater Breslow thickness (BT).

PATIENTS AND METHODS

The study was carried out at four referral melanoma centers (three Italian and one Polish). Clinical consecutive patients with stage I-II melanoma, who were diagnosed, treated, and followed up between January 1998 and March 2018 in annotated specific databases were included.

RESULTS

Overall, 6734 were evaluable, 4349 with superficial spreading melanoma (SSM), 2132 with nodular melanoma (NM), and 253 with ALM. At univariable analysis, a statistically significant worse DFS [hazard ratio (HR) 2.72, 95% confidence interval (CI) 2.24-3.30; P < 0.001] and OS (HR 2.67, 95% CI 2.15-3.32; P < 0.001) were found in patients with ALM compared with SSM. Similarly, the NM histotype was associated with a worse prognosis compared with the SSM histotype (DFS: HR 2.29, 95% CI 2.08-2.52; P < 0.001 and OS: HR 2.21, 95% CI 1.99-2.46; P < 0.001). At multivariable analysis, after adjusting for age, sex, BT, ulceration, and the sentinel lymph node status, a statistically significant worse DFS [adjusted HR (aHR; ALM versus SSM) 1.25, 95% CI 1.02-1.52; P = 0.028] was confirmed for patients with ALM. For patients with NM, instead, no impact of histology was found in terms of DFS [aHR (NM versus SSM) 1.04, 95% CI 0.93-1.15; P = 0.513] and OS [aHR (NM versus SSM) 0.96, 95% CI 0.86-1.08; P = 0.548].

CONCLUSIONS

ALM is associated with a worse long-term DFS. Our results could have important clinical implications for patients' stratification in future clinical trials and the incorporation of ALM histotype in the new AJCC classification as an independent prognostic factor.

Acral lentiginous melanoma-Population, treatment, and survival using the NCDB from 2004 to 2015

Acral lentiginous melanoma (ALM) is a rare histological subtype of cutaneous malignant melanoma that typically presents on the palms and soles. To characterize the demographic and treatment characteristics of ALM, we used the National Cancer Database (NCDB) to describe a large multi-institutional cohort of ALM patients, consisting of 4,796 ALM patients from 2004 to 2015. ALM was more likely to be diagnosed at a later stage overall compared with non-ALM cutaneous melanomas, and more likely to be thicker, ulcerated, lymph node positive, and have lymphovascular invasion and positive margins. When stratified by stage, ALM had worse survival compared with non-ALM patients, most notably in stage III patients with 5-year survival of 47.5% versus 56.7%, respectively (p < .001). In ALM patients, older age, male sex, higher comorbidity burden, increased tumor thickness and ulceration, positive lymph nodes, and positive metastasis were independently associated with lower 5-year survival. Multimodality therapy, defined as surgery in addition to systemic therapy and/or radiation therapy, was associated with higher survival in stage III patients but not in other stages. These results call for further investigation into possible treatment intensification in the ALM population in the future.

Immunotherapy in Acral and Mucosal Melanoma: Current Status and Future Directions

Acral and mucosal melanomas are extremely rare in Caucasians; however, they are the predominant melanoma subtypes in Asians and other non-Caucasian populations. Acral and mucosal melanomas share many clinicopathological features, including aggressive phenotypes, similar genetic landscapes, and grim prognoses. In spite of advances in melanoma management, patients with acral and mucosal melanomas show limited benefit from current therapies. The rarity of these subtypes of melanoma is a significant factor contributing to the poor understanding of these pathological subtypes and the lack of effective interventions. Furthermore, the mechanisms contributing to disparities between different types of melanoma remain largely unclear. Herein, we comprehensively review current knowledge on the clinicopathological characteristics and mutational landscapes of acral and mucosal melanomas, as well as providing an overview of current therapies for patients with these aggressive melanoma subtypes, focusing on available immunotherapeutic interventions. We also discuss pathological differences between different melanoma subtypes and summarize current knowledge on melanoma disparities between Asians and Caucasians. Finally, we discuss emerging immunotherapeutic strategies for the treatment of acral and mucosal melanomas, focusing on combination therapies with immune checkpoint inhibitors. Unraveling the unique features of acral and mucosal melanomas is key for their early diagnosis and for the development of effective therapies.

Clinical Significance of Tumor Microenvironment in Acral Melanoma: A Large Single-Institution Study of Caucasians

Background: The presence of tumor-infiltrating lymphocytes (TILs) in many studies is associated with a better prognosis in melanoma patients. Programmed death-ligand 1 (PD-L1) expression has a significant value in predicting several cancers, but its role in melanoma remains ambiguous. The study aims to report a comprehensive analysis of TILs characteristics and their impact on survival in primary acral melanoma (AM). Methods: Clinical and pathological features and survival outcomes were investigated in 70 patients with AM. Immunohistochemical quantitative analysis of TILs, including expression of CD4, CD8, FOXP3, PD-1, and PD-L1, on melanoma cells was performed. Results: Kaplan-Meier analysis showed significant differences in overall survival (OS) for CD4+ (p = 0.021), CD8+ (p = 0.037), FOXP3+ (p = 0.007), and TILs density (p = 0.043). In univariate analysis of immunohistochemical features, FOXP3, CD4, CD8, PD-1, and Melanoma Institute of Australia (MIA) grading TILs (grade, density, and distribution) were correlated with survival. The higher density of FOXP3-positive cells was an independent factor associated with better survival. Conclusions: High TILs content (classed as brisk Clark scale and marked/diffuse TILs MIA grade) regardless of its immunophenotype was associated with better survival outcomes in AM. PD-L1 expression on tumor cells did not influence OS and was independent of clinical and pathological characteristics. We demonstrated that TILs are significant biomarkers in sentinel lymph node status prediction.

Prognostic significance of acral lentiginous histologic type in T1 melanoma

Acral lentiginous melanoma (ALM) is a rare type of cutaneous melanoma with a poor prognosis. It is unclear whether the poor outcome of ALM is due to its inherent disease characteristics or advanced stage at initial diagnosis. To address this question, we retrospectively analyzed the clinicopathologic factors of 828 thin (T1; Breslow thickness ≤1.0 mm) melanomas [129 (15.6%) ALMs and 699 (84.4%) non-ALMs] and their nodal and distance metastases and local recurrence rates and determined their relationship with the disease-specific (DSS), overall (OS), and recurrence-free survivals (RFS) at the pathologic stages T1, T1a, and T1b with a median follow-up time of 84.5 months. With the exception of OS at T1b stage, ALM patients showed significantly lower 5- and 10-year DSS, OS, and RFS rates at every pathologic stage when compared with non-ALM. In multivariable analysis, ALM histologic type, SLN positivity, age, and the use of systemic therapy were detected as independent poor prognostic factors associated with significantly lower survival rates. ALM histologic type was associated with lower DSS and OS rates at T1 and T1a stages and lower RFS rates at T1b stage. SLN positivity was associated with lower DSS, OS, and RFS rates at T1, T1a, and T1b stages. Age was associated with lower OS rates at T1 and T1b stages. Whereas the use of systemic therapy was associated with lower DSS rates at T1a stage and RFS rates at T1b stage. In addition, the ALM group showed significantly older median age patients and higher rates of female sex, Hispanic ethnicity, nevoid cytology, non-brisk tumor-infiltrating lymphocytes, nodal metastasis, and local recurrence at every pathologic stage of thin melanoma. Our findings suggest that ALM is inherently more aggressive than other types of cutaneous melanoma. This information may be useful for prognostic stratification of patients with thin melanomas, especially to help guide the clinical decision-making for SLN biopsy and patients entering clinical trials.

Immunotherapy for advanced melanoma: current situation in Japan

Treatment with immune checkpoint inhibitors provides long-term survival for patients with advanced melanoma. Improvements in the overall survival of advanced melanoma patients have been achieved with anti-PD-1 monotherapy and anti-PD-1+ CTLA4 combination therapy, but there are still many issues to resolve. Acral, mucosal and uveal melanoma have been less responsive to immune checkpoint inhibitors than cutaneous melanoma. For patients who have achieved a good response, it is still not known how long the anti-PD-1 therapy should be administered. Moreover, there is limited treatment for patients who relapse during or after adjuvant anti-PD-1 therapy. Here, we review the current evidence regarding the clinical effects of immunotherapy for advanced melanoma. Moreover, we review previous studies of acral, mucosal and uveal melanoma, and we discuss the recent findings regarding durable response after the cessation of anti-PD-1 therapy, and treatment options for recurrence after adjuvant therapy.

Poor Lymphocyte Infiltration to Primary Tumors in Acral Lentiginous Melanoma and Mucosal Melanoma Compared to Cutaneous Melanoma

Recent clinical trials have demonstrated the efficacy of immune checkpoint inhibitors (ICIs) for treating melanoma. However, these previous studies comprised mainly Caucasian populations, in which cutaneous melanoma (CM) is the major clinical type. In contrast, Asian populations have a distinct profile of melanoma and show much higher frequencies of acral lentiginous melanoma (ALM) and mucosal melanoma (MCM). Compared with CM, ALM and MCM show poorer response to ICIs, but the mechanisms have not been fully understood. To evaluate the immune status in each melanoma subtype, we examined the number of total tumor-infiltrating lymphocytes (TILs), CD4⁺ TILs, CD8⁺ TILs, and tumor-infiltrating FoxP3⁺ regulatory T cells (Tregs) to evaluate the immune status in each melanoma subtype using data from 137 patients with melanoma. Total TIL numbers in ALM and MCM were significantly lower than that in CM. CD4⁺ TIL number in MCM was also lower than CM although CD4⁺ TIL number in ALM was comparable with CM. In contrast, CD8⁺ TIL numbers in both ALM and MCM were significantly lower than that in CM. Although number of tumor-infiltrating Tregs was comparable among the 3 subtypes, the proportion of tumor-infiltrating Tregs in CD4⁺ T cells in MCM was significantly higher than in CM and ALM. Multivariate regression analysis revealed that ALM and MCM were significantly associated with a lower total TIL number, but only MCM was significantly associated with a lower CD4⁺ TIL number. Multivariate regression analysis also revealed that both ALM and MCM were significantly associated with a lower CD8⁺ TIL number. Our results suggest that both ALM and MCM are independent factors of lower total TIL number, which may be associated with poorer responses to ICIs in ALM and MCM.

Prognostic Significance of Subungual Anatomic Site in Acral Lentiginous Melanoma

CONTEXT.—

Acral lentiginous melanoma is a rare and aggressive type of cutaneous melanoma that arises on the acral skin and the nail unit. The prognostic significance of subungual anatomic site in acral lentiginous melanoma is not established.

OBJECTIVE.—

To assess the impact of subungual anatomic site on overall survival and disease-specific survival in acral lentiginous melanoma.

DESIGN.—

Retrospective cohort analysis. Clinicopathologic characteristics of 627 primary acral lentiginous melanomas (45 [7%] subungual and 582 [93%] nonsubungual) were summarized, and the impact of these characteristics on overall survival and disease-specific survival was determined using univariate and multivariable analyses.

RESULTS.—

No significant differences in clinicopathologic features were identified between the subungual and nonsubungual acral lentiginous melanomas. The 1-, 5-, and 10-year overall survival rates were 81%, 40%, and 28%, respectively, for subungual acral lentiginous melanoma and 94%, 59%, and 38%, respectively, for nonsubungual acral lentiginous melanoma (P = .04); risk of death was significantly higher for subungual tumors (hazard ratio [95% confidence interval] = 1.59 [1.02-2.50]; P = .04). The 1-, 5-, and 10-year disease-specific survival rates were 94%, 56%, and 48%, respectively, for subungual acral lentiginous melanoma versus 96%, 69%, and 55%, respectively, for nonsubungual acral lentiginous melanoma (P = .18). By multivariable analysis, independent poor prognostic factors included older age and ulceration for overall survival and greater Breslow thickness and sentinel lymph node positivity for overall survival and disease-specific survival. Subungual anatomic site was not an independent prognostic factor for overall or disease-specific survival.

CONCLUSIONS.—

Subungual anatomic site is not an independent prognostic factor for acral lentiginous melanoma.

Immune Checkpoint Inhibitors in Advanced Acral Melanoma: A Systematic Review

Introduction

Acral melanoma (AM) has different biological characteristics from cutaneous melanoma. Although systemic therapeutic strategies for advanced AM resemble those for advanced cutaneous melanoma, the evidence of the clinical use of immune checkpoint inhibitors (ICIs) for AM is still inadequate. We aimed to systematically analyze the therapeutic effects and safety profile of ICI treatments in advanced AM.

Methods

This systematic review was conducted in line with a previously registered protocol. Three electronic databases, conference abstracts, clinical trial registers, and reference lists of included articles were searched for eligible studies. The primary outcomes were therapeutic effects, and the secondary outcomes were the safety profiles.

Results

This systematic review included six studies investigating anti-CTLA-4 immunotherapy, 12 studies investigating anti-PD-1 immunotherapy, one study investigating the combination therapy of anti-CTLA-4 and anti-PD-1, and one study investigating anti-PD-1 immunotherapy in combination with radiotherapy. In most studies investigating ipilimumab, the anti-CTLA-4 antibody, the objective response rate ranged from 11.4 to 25%, the median progression-free survival ranged from 2.1 to 6.7 months, and the median overall survival was more than 7.16 months. For studies discussing anti-PD-1 immunotherapy with nivolumab, pembrolizumab, or JS001, the objective response rate ranged from 14 to 42.9%, the median progression-free survival ranged from 3.2 to 9.2 months, and the median overall survival was more than 14 months. The combination therapy of anti-CTLA-4 and anti-PD-1 immunotherapy showed better efficacy with an objective response rate of 42.9% than single-agent therapy. The retrospective study investigating the combination therapy of anti-PD-1 immunotherapy and radiation showed no overall response. Few outcomes regarding safety were reported in the included studies.

Conclusions

ICIs, especially anti-CTLA-4 monoclonal antibodies combined with anti-PD-1 antibodies, are effective systematic treatments in advanced AM. However, there remains a lack of high-level evidence to verify their efficacy and safety and support their clinical application.

Acral lentiginous melanoma: A retrospective study

BACKGROUND

Acral lentiginous melanoma (ALM) carries one of the worst prognoses among other subtypes. This malignant tumor is found on the distal limbs and is usually detected at late stages. Hereby, the authors present their experience on this melanoma subtype.

METHODS

A retrospective study was conducted. Data were extracted from patients' medical records and from phone interviews.

RESULTS

A total of 43 patients were included in the study. The main signs and symptoms disclosed by the patients were bleeding (41.9%), size greater than 6 mm (41.9%), change in size (37.2%), change in shape (30.2%), rise above the surface of the skin (27.9%), change in color (20.9%), irregular borders (16.3%), and inflammation (16.3%). The first healthcare professional consulted was a general practitioner or a dermatologist in the majority of cases (88.3%). Only 44.2% of the patients were sent by their first physician for a biopsy, whereas 30.3% were sent by the 2nd physician. 14 patients underwent biopsy within 1 month from the first appointment with a physician, while 20 patients within 3 months and 9 patients within 6 months. Only 7 patients sought medical attention in the first 3 months; 21 patients sought medical care between 3 months and one year from the appearance of the lesion, while the remaining 15 patients waited more than a year.

CONCLUSIONS

One of the major issues found in ALM is represented by the diagnostic delay; this may be due to either the patients or the physicians' failure to recognize warning signs.

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.

Early Stroke Induces Long-Term Impairment of Adult Neurogenesis Accompanied by Hippocampal-Mediated Cognitive Decline

Stroke increases neurogenesis in the adult dentate gyrus in the short term, however, long-term effects at the cellular and functional level are poorly understood. Here we evaluated the impact of an early stroke lesion on neurogenesis and cognitive function of the aging brain. We hypothesized that a stroke disturbs dentate neurogenesis during aging correlate with impaired flexible learning. To address this issue a stroke was induced in 3-month-old C57Bl/6 mice by a middle cerebral artery occlusion (MCAO). To verify long-term changes of adult neurogenesis the thymidine analogue BrdU (5-Bromo-2′-deoxyuridine) was administrated at different time points during aging. One and half months after BrdU injections learning and memory performance were assessed with a modified version of the Morris water maze (MWM) that includes the re-learning paradigm, as well as hippocampus-dependent and -independent search strategies. After MWM performance mice were transcardially perfused. To further evaluate in detail the stroke-mediated changes on stem- and progenitor cells as well as endogenous proliferation nestin-green-fluorescent protein (GFP) mice were used. Adult nestin-GFP mice received a retroviral vector injection in the hippocampus to evaluate changes in the neuronal morphology. At an age of 20 month the nestin-GFP mice were transcardially perfused after MWM performance and BrdU application 1.5 months later. The early stroke lesion significantly decreased neurogenesis in 7.5- and 9-month-old animals and also endogenous proliferation in the latter group. Furthermore, immature doublecortin (DCX)-positive neurons were reduced in 20-month-old nestin-GFP mice after lesion. All MCAO groups showed an impaired performance in the MWM and mostly relied on hippocampal-independent search strategies. These findings indicate that an early ischemic insult leads to a dramatical decline of neurogenesis during aging that correlates with a premature development of hippocampal-dependent deficits. Our study supports the notion that an early stroke might lead to long-term cognitive deficits as observed in human patients after lesion.

Level of tumor-infiltrating lymphocytes and density of infiltrating immune cells in different malignancies

Aim: To correlate levels of tumor-infiltrating lymphocytes (TIL) evaluated using the International Immuno-Oncology Biomarker Working Group methodology, and both density of tumor-infiltrating immune cell and clinicopathological features in different malignancies. Methods: 209 pathological samples from gastric cancer, cervical cancer (CC), non-small-lung cancer, cutaneous melanoma (CM) and glioblastoma were tested for TIL in hematoxylin eosin, and density of CD3+, CD4+, CD8+, CD20+, CD68+ and CD163+ cells by digital analysis. Results: TIL levels were higher in invasive margin compartments (IMC). TIL in IMC, intratumoral and stromal compartments predicted survival. CC and gastric cancer had higher TIL in intratumoral; CC and CM had higher TIL in stromal compartment and IMC. CM had the highest density of lymphocyte and macrophage populations. CD20 density was associated with survival in the whole series. Conclusion: Standardized evaluation of TIL levels may provide valuable prognostic information in a spectrum of different malignancies.

Translational pathology, genomics and the development of systemic therapies for acral melanoma

Acral melanomas arise on the non-hair bearing skin of the palms, soles and in the nail beds. These rare tumors comprise 2-3 % of all melanomas, are not linked to UV-exposure, and represent the most frequent subtype of melanomas in patients of Asian, African and Hispanic origin. Although recent work has revealed candidate molecular events that underlie acral melanoma development, this knowledge is not yet been translated into efficacious local, regional, or systemic therapies. In the current review, we describe the clinical characteristics of acral melanoma and outline the genetic basis of acral melanoma development. Further discussion is given to the current status of systemic therapy for acral melanoma with a focus on ongoing developments in both immunotherapy and targeted therapy for the treatment of advanced disease.

Relationship between tumor-associated immune infiltrate and p16 staining over clinicopathological features in acral lentiginous melanoma

PURPOSE

This study aims to evaluate the association between composition of tumor-infiltrating lymphocytes (TIL) and expression of p16 in acral lentiginous melanoma (ALM), and their impact on prognosis.

MATERIALS AND METHODS

A cohort of 148 surgical pathology specimens of ALM was studied. TIL were evaluated by immunohistochemical detection of CD3 and CD8, along with CD20, CD4, CD68, and CD163 in a subset of 43 cases. p16 protein expression was also investigated in all the cases.

RESULTS

The median age was 66 years, median Breslow thickness was 6.0 mm, grade III TIL was found in 28.4% and lymph nodes were involved in 54.2%. Breslow thickness (p < 0.001), stage I-II (p < 0.001), negative lymph nodes (p < 0.001) and < 10% p16 (p = 0.01) were associated with longer survival. Grade III of TIL was associated with thinner Breslow thickness (p = 0.008) and lower mitosis (p = 0.047). A higher density of CD3 TIL was associated with male gender (p = 0.008), thinner Breslow thickness (p = 0.047), negative lymph node (p = 0.031), early stage (p = 0.046), and p16 nuclear expression of > 10% (p = 0.045). Higher CD8 TIL was associated with > p16 (p = 0.03). Survival analysis found that longer survival had a trend to be associated with high TIL (p = 0.090). Levels of CD3+ and CD8+ cells were correlated with those of CD4+, CD20+, CD68+ and CD163+ immune cells.

CONCLUSIONS

Higher levels of TIL tend to be associated with better overall survival in ALM. Loss of expression of p16 is associated with lower levels of CD3+ and CD8+ TIL, indicating a probable relationship between p16 and TIL immune response in ALM .

Identification of a functional polymorphism within the 3'-untranslated region of denticleless E3 ubiquitin protein ligase homolog associated with survival in acral melanoma

BACKGROUND

High expression of denticleless E3 ubiquitin protein ligase homologue (DTL) correlates with poor disease-free survival and overall survival in cutaneous melanoma, but the molecular features and clinical significance of this gene in acral melanoma (AM) remain unclear.

METHODS

The expression levels of DTL were compared between AM and benign melanocytic nevi using existing Gene Expression Omnibus data and validated in fresh frozen tissues. Two candidate tag single-nucleotide polymorphisms (SNPs) in the 3'-untranslated region (3'UTR) of DTL in patients with AM were sequenced and analysed for their association with survival in a discovery cohort (n = 570), and the significant SNP was subjected to a replication cohort (n = 201). The expression of DTL was evaluated by immunohistochemistry. The microRNA interacting with rs11275300:C > G was predicted using in silico target prediction tools and validated by in vitro analysis.

RESULTS

DTL was overexpressed in AM compared with benign melanocytic nevi. rs11275300:C > G was found to be significantly associated with progression-free survival and overall survival of patients with AM in both cohorts and the combined cohort. Furthermore, the DTL expression level in the patients with the rs11275300:G allele was higher than that in patients with the CC genotype. In vitro analysis demonstrated that DTL was a direct target of hsa-miR-4672, and the rs11275300:G allele interfered with the binding affinity of hsa-miR-4672 with the 3'UTR of DTL and thereby increased DTL expression.

CONCLUSION

The rs11275300:G allele in the 3'UTR of DTL may lead to a poor prognosis and allele-specific increase in the expression of DTL by post-transcriptional regulation in AM.

Prognostic value of tumor-infiltrating lymphocytes in melanoma: a systematic review and meta-analysis

Tumor-infiltrating lymphocytes (TILs) are associated with prognosis in various tumors. However, it remains controversial whether the presence of TILs is related to an improved prognosis in melanoma. This meta-analysis confirmed the favorable prognostic role of the CD3+, CD4+, CD8+, FOXP3+, and CD20+ TILs in the overall survival of melanoma patients and found an association between the TILs present and improved overall survival. Additionally, subgroup analysis demonstrated that brisk TILs were obviously associated with OS, RFS and DSS/MSS. Thus, TILs may be a predictive biomarker in melanoma. This analysis will provide more insight into the study of TILs and predictive biomarker.

Comparison of five different scoring methods in the evaluation of inflammatory infiltration (tumor-infiltrating lymphocytes) in superficial spreading and nodular melanoma

The objective of our study was to compare the five different scoring methods of tumor-infiltrating lymphocytes (TILs) assessment in a group of 213 cases of superficial spreading and nodular melanoma. The scoring methods include (a) Clark scoring; (b) Melanoma Institute Australia system; (c) scoring system used in the study of Saldanha et al.; (d) scoring system used in the TCGA study and modified by Park et al.; and (e) the system recently proposed by the "International Immuno-Oncology Biomarker Working Group" for TILs scoring in all solid tumors. Prediction of survival with three main outcomes-disease-specific-free survival, local recurrence-free survival, and distant metastasis-free survival-was evaluated. The prognostic value of TILs showed statistical significance in univariate analysis regarding all three of the outcomes only for three of the five evaluated methods; the Clark scoring, the Melanoma Institute Australia system, and the system proposed by the "International Immuno-Oncology Biomarker Working Group". However, in multivariate analysis with covariants including Breslow thickness, type of melanoma, location, sex, and age, we did not find TILs to be an independent prognostic factor.

Clinicopathological significance of tumor-infiltrating lymphocytes and programmed death-1 expression in cutaneous melanoma: a comparative study on clinical subtypes

Interactions between immune cells and tumor cells play an important role in tumor progression. We evaluated patterns of tumor-infiltrating lymphocytes (TILs) and programmed death-1 (PD-1) expression in acral and nonacral cutaneous melanoma, and determined their effects on clinicopathological characteristics and biologic responses. We identified 122 cases of cutaneous melanoma, of which 39 were cases of non-nail unit acral melanoma (NNUAM), 35 were cases of nail unit melanoma (NUM), and 48 were cases of nonacral melanoma. Clinicopathological features and survival outcomes were analyzed according to the scores for TILs and PD-1 expression in intratumoral and peritumoral compartments. The effects of the presence of TILs and PD-1 expression on various clinicopathological factors differed according to the clinical subtypes of cutaneous melanoma. The frequency of intratumoral TILs and PD-1 expression were lower in NUM than in the other two subtypes. The density of peritumoral PD-1 was significantly higher in NNUAM. In NUM and nonacral melanoma, a low density of intratumoral TILs and PD-1 was associated with a deeper Breslow thickness and the presence of a vertical growth phase. In NNUAM, a high density of peritumoral TILs and PD-1 was associated with a shallower Breslow thickness and less frequent extracutaneous dissemination. In NNUAM, a high density of peritumoral PD-1 was associated with a better prognosis. This study suggests that the effects of PD-1+ TILs on biological activity differ according to the clinical subtypes of cutaneous melanoma.

Diagnosis and Management of Acral Lentiginous Melanoma

OPINION STATEMENT

Melanoma is one of the most aggressive malignant skin tumors and its incidence has been increasing worldwide in recent decades. Among the four subtypes, acral lentiginous melanoma (ALM) shows the highest incidence in Asian countries, whereas ALM comprises only 1% of all melanomas in white populations. Early clinical diagnosis of ALM is essential, but early ALM lesions are often difficult to diagnose because the pigmentation of the lesions sometimes follows the skin marking of the palms and soles, resulting in an asymmetrical appearance and an irregular border in both ALM and benign melanocytic nevus. To overcome this difficulty, dermoscopy was introduced, and determination of the patterns by this method is essential for accurate clinical diagnosis of ALM. Although recent clinical trials have demonstrated that immune checkpoint inhibitors and BRAF/MEK inhibitors showed significantly improved overall survival of patients with advanced melanoma, ALM may be less susceptible to immune checkpoint inhibitors because of the poor immune response to the tumor. Therefore, strategies for enhancing the immune response to the tumor cells may be required when we apply immune checkpoint inhibitors in advanced ALM. In this context, imiquimod, dacarbazine, or interferon are possible therapies that may enhance the effectiveness of the immune checkpoint inhibitors. In addition to being known to have poor immunogenicity, ALM is also known to have infrequent BRAF mutation. Therefore, the majority of ALM patients may not benefit from therapy with BRAF/MEK inhibitors. However, some ALMs have mutations such as KIT and NRAS mutations, and therefore, targeted therapies may improve the survival of ALM patients in the future.

The Major Role of NF-κB in the Depth of Invasion on Acral Melanoma by Decreasing CD8+ T Cells

BACKGROUND

The tumor microenvironment including immune surveillance affects malignant melanoma (MM) behavior. Nuclear factor κB (NF-κB) stimulates the transcription of various genes in the nucleus and plays a role in the inflammatory process and in tumorigenesis. CD8⁺ T cells have cytotoxic properties important in the elimination of tumors. However, inhibitory receptors on the cell surface will bind to programmed death-ligand 1 (PD-L1), causing CD8⁺ T cells to lose their ability to initiate an immune response. This study analyzed the association of NF-κB and PD-L1 expression levels and CD8⁺ T-cell counts with depth of invasion of acral MM, which may be a predictor of aggressiveness related to an increased risk of metastasis.

METHODS

A retrospective cross-sectional study was conducted in the Department of Anatomical Pathology, Faculty of Medicine, Universitas Padjadjaran/Hasan Sadikin Hospital using 96 cases of acral melanoma. Immunohistochemical staining was performed on paraffin blocks using anti-NF-κB, -PD-L1, and -CD8 antibodies and invasion depth was measured using dotSlide-imaging software.

RESULTS

The study showed significant associations between the individual expression of NF-κB and PD-L1 and CD8⁺ T-cell number, with MM invasion depth. NF-κB was found to be a confounding variable of CD8⁺ T-cell number (p < .05), but not for PD-L1 expression (p = .154). Through multivariate analysis it was found that NF-κB had the greatest association with the depth of invasion (p < .001), whereas PD-L1 was unrelated to the depth of invasion because it depends on the number of CD8⁺ T cells (p = .870).

CONCLUSIONS

NF-κB plays a major role in acral MM invasion, by decreasing the number of CD8⁺ T cells in acral MM.