The Effect of Neoadjuvant Systemic Therapy on Surgical Outcomes After Lymph Node Dissections for Stage III Melanoma; An Australian Cohort.

BACKGROUND: Neoadjuvant systemic therapy (NAST) for patients with stage III melanoma achieves high major pathologic response rates and high recurrence-free survival rates. This study aimed to determine how NAST with targeted therapies (TTs) and immune checkpoint inhibitors (ICIs) influences surgical outcomes after lymph node dissection in terms of complications, morbidity, and textbook outcomes. METHODS: Patients who underwent a lymph node dissection after either NAST in a clinical trial or upfront surgery for stage III melanoma between 2014 and 2022 were identified from an institutional research database. RESULTS: The study included 89 NAST-treated patients and 79 upfront surgery-treated patients. The rate of postoperative complications did not differ between the NAST- and upfront surgery-treated patients (55% vs. 51%; p = 0.643), and steroid treatment for drug toxicity did not influence the complication rate (odds ratio [OR], 1.1; 95% confidence interval [CI], 0.4-3; p = 0.826). No significant differences in postoperative morbidity were observed in terms of seroma (23% vs. 11%; p = 0.570) or lymphedema (36% vs. 51%; p = 0.550). The rate of achieving a textbook outcome was comparable for the two groups (61% vs. 57%; p = 0.641). CONCLUSIONS: The surgical outcomes after lymph node dissections were comparable between the patients who received NAST and those who had upfront surgery, indicating that surgery can be safely performed after NAST with TT or ICI for stage III melanoma.

Impact of an Online Risk Calculator for Sentinel Node Positivity on Management of Patients with T1 and T2 Melanomas.

BACKGROUND: Predicting which patients with American Joint Committee on Cancer (AJCC) T1-T2 melanomas will have a positive sentinel lymph node (SLN) is challenging. Melanoma Institute Australia (MIA) developed an internationally validated SLN metastatic risk calculator. This study evaluated the nomogram's impact on T1-T2 melanoma patient management at MIA. METHODS: SLN biopsy (SLNB) rates were compared for the pre- and post-nomogram periods of 1 July 2018-30 June 2019 and 1 August 2020-31 July 2021, respectively. RESULTS: Overall, 850 patients were identified (pre-nomogram, 383; post-nomogram, 467). SLNB was performed in 29.0% of patients in the pre-nomogram group and 34.5% in the post-nomogram group (p = 0.091). The overall positivity rate was 16.2% in the pre-nomogram group and 14.9% in the post-nomogram group (p = 0.223). SLNB was performed less frequently in T1a melanoma patients in the pre-nomogram group (1.1%, n = 2/177) than in the post-nomogram group (8.6%, n = 17/198) [p ≤ 0.001]. This increase was particularly for melanomas with a risk score ≥ 5%, with an SLN positivity rate of 11.8% in the post-nomogram group (p = 0.004) compared with zero. For T1b melanomas with a risk score of > 10%, the SLNB rate was 40.0% (8/20) pre-nomogram and 75.0% (12/16) post-nomogram (p = 0.049). CONCLUSIONS: In this specialized center, the SLN risk calculator appears to influence practice for melanomas previously considered low risk for metastasis, with increased use of SLNB for T1a and higher-risk T1b melanomas. Further evaluation is required across broader practice settings. Melanoma management guidelines could be updated to incorporate the availability of nomograms to better select patients for SLNB than previous criteria.

Five-year analysis of neoadjuvant dabrafenib and trametinib for stage III melanoma.

BACKGROUND: Neoadjuvant dabrafenib plus trametinib has a high pathological response rate and impressive short-term survival in patients with resectable stage III melanoma. We report five-year outcomes from the phase II NeoCombi trial. METHODS: NeoCombi (NCT01972347) was a single-arm, open-label, single-centre, phase II trial. Eligible patients were adults (aged ≥18) with histologically-confirmed, resectable, RECIST-measurable AJCC 7th ed. clinical stage IIIB-C BRAF V600E/K-mutant melanoma and Eastern Co-operative Oncology Group performance status ≤1. Patients received 52 weeks of treatment with 150 mg dabrafenib (orally twice per day) plus 2 mg trametinib (orally once per day), with complete resection of the pre-therapy tumour bed at Week 12. RESULTS: Between August 20, 2014, and April 19, 2017, 35 patients were enrolled. At data cut-off (August 17, 2021), the median follow-up was 60 months (95% CI 56-72). Overall, 21 of 35 (60%) patients recurred, including twelve (57%) with first recurrence in locoregional sites (followed by later distant recurrence in six) and nine (43%) with first recurrence in distant sites, including three in the brain. Most recurrences occurred within two years, with no recurrences beyond three years. At five years, recurrence-free survival was 40% (95% CI 27-60), distant metastasis-free survival was 57% [95% CI 42-76%], and overall survival was 80% (95% CI 67-94). Five-year survival outcomes were stratified by pathological response: recurrence-free survival was 53% with pCR versus 28% with non-pCR (p=0.087), distant metastasis-free survival was 59% versus 55% (p=0.647), and overall survival was 88% versus 71% (p=0.205), respectively. CONCLUSIONS: Neoadjuvant dabrafenib plus trametinib has high pathological response rates in clinical stage III melanoma, but low rates of recurrence-free survival, similar to those achieved with adjuvant targeted therapy alone. Patients with a pCR to dabrafenib plus trametinib still had a high risk of recurrence, unlike that seen with immunotherapy where recurrences are rare.

Predicting Recurrence-Free and Overall Survival for Patients With Stage II Melanoma: The MIA Calculator.

PURPOSE: Improvements in recurrence-free survival (RFS) were demonstrated in two recent randomized trials for patients with sentinel node (SN)-negative stage IIB or IIC melanoma receiving adjuvant systemic therapy (pembrolizumab/nivolumab). However, adverse events also occurred. Accurate individualized prognostic estimates of RFS and overall survival (OS) would allow patients to more accurately weigh the risks and benefits of adjuvant therapy. Since the current American Joint Committee on Cancer eighth edition (AJCC-8) melanoma staging system focuses on melanoma-specific survival, we developed a multivariable risk prediction calculator that provides estimates of 5- and 10-year RFS and OS for these patients. METHODS: Data were extracted from the Melanoma Institute Australia (MIA) database for patients diagnosed with stage II (clinical or pathological) melanoma (n = 3,220). Survival prediction models were developed using multivariable Cox regression analyses (MIA models) and externally validated twice using data sets from the United States and the Netherlands. Each model's performance was assessed using C-statistics and calibration plots and compared with Cox models on the basis of AJCC-8 staging (stage models). RESULTS: The 5-year and 10-year RFS C-statistics were 0.70 and 0.73 (MIA-model) versus 0.61 and 0.60 (stage-model), respectively. For OS, the 5-year and 10-year C-statistics were 0.71 and 0.75 (MIA-model) compared with 0.62 and 0.61 (stage-model), respectively. The MIA models were well calibrated and externally validated. CONCLUSION: The MIA models offer accurate and personalized estimates of both RFS and OS in patients with stage II melanoma even in the absence of pathological staging with SN biopsy. These models were robust on external validations and may be used in everyday practice both with (ideally) and without performing SN biopsy to identify high-risk patients for further management strategies. An online tool will be available at the MIA website (Risk Prediction Tools).

Role of Concurrent Ultrasound Surveillance of Sentinel Node-Positive Node Fields in Melanoma Patients Having Routine Cross-Sectional Imaging.

PURPOSE: In sentinel node-positive (SN+ve) melanoma patients, active surveillance with regular ultrasound examination of the node field has become standard, rather than completion lymph node dissection (CLND). A proportion of these patients now receive adjuvant systemic therapy and have routine cross-sectional imaging (computed tomography [CT] or positron emission tomography [PET]/CT). The role of concurrent ultrasound (US) surveillance in these patients is unclear. The purpose of our study was to describe the modality of detection of nodal recurrence in SN+ve node fields. METHODS: SN+ve melanoma patients who did not undergo CLND treated at a single institution from January 1, 2016 to December 31, 2020 were included. RESULTS: A total of 225 SN+ve patients with a median follow-up of 23 months were included. Of these, 119 (53%) received adjuvant systemic therapy. Eighty (36%) developed a recurrence at any site; 24 (11%) recurred first in the SN+ve field, of which 12 (5%) were confirmed node field recurrence only at 2 months follow-up. The nodal recurrences were first detected by ultrasound in seven (3%), CT in seven (3%), and PET/CT in seven (3%) patients. All nodal recurrences evident on US were also evident on PET/CT and vice versa. CONCLUSIONS: The high rate of recurrences outside the node field and the identification of all US-detected nodal recurrences on concurrent cross-sectional imaging modalities suggest that routine concurrent ultrasound surveillance of the node-positive field may be unnecessary for SN+ve melanoma patients having routine cross-sectional imaging.

Prognostic Significance of Incipient Ulceration in Primary Cutaneous Melanoma.

Importance: Ulceration represents a key feature in cutaneous melanoma, contributing to staging according to the current American Joint Committee on Cancer (AJCC) system. However, cases with incipient ulceration do not quite fulfill the AJCC definition of ulceration and are consequently classified as nonulcerated, presenting interpretive difficulty for pathologists. The prognostic implication of incipient ulceration is uncertain. Objective: To evaluate the prognostic significance of incipient ulceration in cutaneous melanoma. Design, Setting, and Participants: This case-control study consisted of resected primary cutaneous melanomas diagnosed between 2005 and 2015, identified from the Melanoma Institute Australia research database and with slides available for review at Royal Prince Alfred Hospital. Slides were reviewed by pathologists experienced in the diagnosis of melanocytic lesions to identify cases (incipient ulceration) and controls (ulcerated or nonulcerated). Incipient ulceration cases were matched at a 1:2 ratio with nonulcerated and ulcerated controls, respectively. Study analysis was conducted from March to June 2023. Main Outcomes: Clinicopathological factors and clinical outcomes: overall survival (OS), melanoma-specific survival (MSS), and recurrence-free survival (RFS) were compared between cases and controls. Results: Of 2284 patients with melanoma identified, 340 patients (median [IQR] age, 69 [24-94] years; 136 [68%] men; median follow-up, 7.2 years) met the criteria. The matched cohort consisted of 40 cases of incipiently ulcerated melanoma matched 1:2 with 80 nonulcerated controls, and 80 ulcerated controls. The median (IQR) Breslow thickness differed significantly between cases and controls; 2.8 (1.7-4.1) mm for incipient cases compared with 1.0 (0.6-2.1) mm and 5.3 (3.5-8.0) mm for nonulcerated and ulcerated melanomas, respectively. Median (IQR) tumor mitotic rate was 5.0 (3.0-9.0) per mm2 in incipiently ulcerated cases compared with 1 (0-3.0) per mm2 in nonulcerated controls and 9 (5.0-14.0) per mm2 in ulcerated controls. Based on the matched cohorts, patients with nonulcerated tumors had significantly better OS (hazard ratio [HR], 0.49; 95% CI, 0.27-0.88; P = .02) and RFS (HR, 0.37; 95% CI, 0.22-0.64; P < .001) than patients with incipient ulceration. The RFS was significantly worse in ulcerated tumors compared with incipiently ulcerated cases (HR, 1.67; 95% CI, 1.07-2.60; P = .03). After adjusting for pathological factors, no statistically significant differences in clinical outcomes were observed between cases and either control group. Conclusions and Relevance: The findings of this case-control study indicate that incipient ulceration in a primary melanoma represents an adverse prognostic feature that should be noted by pathologists in their reports and considered in future guidelines.

Uncovering the complex relationship between balding, testosterone and skin cancers in men.

Male-pattern baldness (MPB) is related to dysregulation of androgens such as testosterone. A previously observed relationship between MPB and skin cancer may be due to greater exposure to ultraviolet radiation or indicate a role for androgenic pathways in the pathogenesis of skin cancers. We dissected this relationship via Mendelian randomization (MR) analyses, using genetic data from recent male-only meta-analyses of cutaneous melanoma (12,232 cases; 20,566 controls) and keratinocyte cancers (KCs) (up to 17,512 cases; >100,000 controls), followed by stratified MR analysis by body-sites. We found strong associations between MPB and the risk of KC, but not with androgens, and multivariable models revealed that this relationship was heavily confounded by MPB single nucleotide polymorphisms involved in pigmentation pathways. Site-stratified MR analyses revealed strong associations between MPB with head and neck squamous cell carcinoma and melanoma, suggesting that sun exposure on the scalp, rather than androgens, is the main driver. Men with less hair covering likely explains, at least in part, the higher incidence of melanoma in men residing in countries with high ambient UV.

Travel-associated cost savings to patients and the health system through provision of specialist head and neck surgery outreach clinics in rural New South Wales, Australia.

INTRODUCTION: Centralisation of head and neck surgical services means that patients in regional and remote Australia need to travel long distances for treatment and follow-up, imparting a significant financial burden on patients and the health system. OBJECTIVE: To estimate costs of travel to local outreach clinics and determine potential cost savings to patients and the health system by avoiding patient travel to major cities for head and neck surgical care. DESIGN: Retrospective audit of three head and neck surgery outreach clinics in New South Wales, Australia over 4 years (2017-2020). Direct costs of travel from a patient's residence to their local outreach clinic were estimated. Costs of travel and accommodation to Sydney for an appointment were calculated for different travel modes. Estimated reimbursements for travel through government support schemes were calculated based on published rates. FINDINGS: Some 657 patients attended the three clinics, accounting for 1981 appointments. Depending on mode of travel, the estimated median cost of return travel (including accommodation) to Sydney was $379 to $739 per patient per trip and the median government reimbursement ranged from $182 to $279 per trip. In comparison, the cost of return travel by car to local outreach clinics ranged from $28 to $163 per appointment. Outreach clinics were estimated to save patients a median of $285 per trip and avoided government reimbursements of $215 per trip. DISCUSSION: Despite uptake in telehealth, outreach medical services remain an important asset for people living in regional areas to address inequities in access. However, the cost benefits are likely to be underestimated as our approach did not account for indirect costs associated with travel. CONCLUSION: Outreach head and neck surgical services located in regional areas can reduce the financial burden on both patients and the healthcare system. Greater investment in outreach clinics could ensure sustainability of services to promote equitable access to specialised surgical services.

Improving Selection for Sentinel Lymph Node Biopsy Among Patients With Melanoma.

Importance: Refining eligibility guidelines may identify more appropriate patients to undergo useful medical procedures. Objective: To improve cost-effectiveness in selecting patients with melanoma for sentinel lymph node biopsy (SLNB). Design, Setting, and Participants: This hybrid prognostic study/decision analytical model was conducted among patients with melanoma who were eligible for SLNB at 2 melanoma centers from Australia and the US from 2000 to 2014. Participants consisted of 2 cohorts of patients with melanoma undergoing SLNB and a cohort of eligible patients without SLNB. Individualized probabilities of SLNB positivity generated by a patient-centered methodology (PCM) were compared with those generated by conventional multiple logistic regression analysis investigating 12 prognostic factors. Prognostic accuracy was assessed by the area under the receiver operating characteristic curve (AUROC) for each methodology and by matched-pair analyses. Interventions: Triaging appropriate patients to undergo SLNB. Main Outcomes and Measures: Total number of SLNBs performed (giving total cost) vs number of SLNB-positive outcomes (a measure of effectiveness) was evaluated. Improved cost-effectiveness through judicious patient selection was interpreted as increased numbers of SLNB-positive outcomes achieved, decreased numbers of SLNBs performed, or both outcomes simultaneously. Results: Among 7331 patients with melanoma, SLNB outcomes were assessed in 3640 Australian patients (2212 males [60.8%]; 2447 aged >50 years [67.2%]) and 1342 US patients (774 males [57.7%]; 885 aged >50 years [66.0%]); 2349 patients eligible for SLNB who did not undergo the procedure were included in the simulation. PCM-generated probabilities achieved an AUROC of 0.803 in predicting SLNB positivity in the Australian cohort and 0.826 in the US cohort, higher than corresponding AUROCs generated by conventional logistic regression analysis. In simulation, adopting many SLNB-positive probabilities as minimally acceptable patient-selection criteria resulted in fewer procedures performed or increased the expected numbers of positive SLNBs. A minimally acceptable PCM-generated probability of 8.7% elicited the same number of SLNBs as historically performed (3640 SLNBs), with 1066 positive SLNBs (29.3%), constituting an improvement of 287 additional positive SLNBs compared with 779 actual positive SLNBs (36.8% improvement). In contrast, adopting a 23.7% PCM-generated minimum cutoff probability resulted in performing 1825 SLNBs, or 1815 fewer SLNBs than the actual experience (49.9%). It resulted in the same expected number of positive results (779 SLNBs), for a 42.7% positivity rate. Conclusions and Relevance: This prognostic study/decision analytical model found that the PCM approach outperformed conventional multiple logistic regression analysis in predicting which patients would have positive results on SLNB. These findings suggest that systematically producing and exploiting more accurate SLNB-positivity probabilities could improve the selection of patients with melanoma for SLNB compared with using established guidelines, thus improving the cost-effectiveness of the selection process. Eligibility guidelines to undergo SLNB should include a context-tailored minimum cutoff probability.

Cross-platform comparison of immune signatures in immunotherapy-treated patients with advanced melanoma using a rank-based scoring approach.

BACKGROUND: Gene expression profiling is increasingly being utilised as a diagnostic, prognostic and predictive tool for managing cancer patients. Single-sample scoring approach has been developed to alleviate instability of signature scores due to variations from sample composition. However, it is a challenge to achieve comparable signature scores across different expressional platforms. METHODS: The pre-treatment biopsies from a total of 158 patients, who have received single-agent anti-PD-1 (n = 84) or anti-PD-1 + anti-CTLA-4 therapy (n = 74), were performed using NanoString PanCancer IO360 Panel. Multiple immune-related signature scores were measured from a single-sample rank-based scoring approach, singscore. We assessed the reproducibility and the performance in reporting immune profile of singscore based on NanoString assay in advance melanoma. To conduct cross-platform analyses, singscores between the immune profiles of NanoString assay and the previous orthogonal whole transcriptome sequencing (WTS) data were compared through linear regression and cross-platform prediction. RESULTS: singscore-derived signature scores reported significantly high scores in responders in multiple PD-1, MHC-1-, CD8 T-cell-, antigen presentation-, cytokine- and chemokine-related signatures. We found that singscore provided stable and reproducible signature scores among the repeats in different batches and cross-sample normalisations. The cross-platform comparisons confirmed that singscores derived via NanoString and WTS were comparable. When singscore of WTS generated by the overlapping genes to the NanoString gene set, the signatures generated highly correlated cross-platform scores (Spearman correlation interquartile range (IQR) [0.88, 0.92] and r2 IQR [0.77, 0.81]) and better prediction on cross-platform response (AUC = 86.3%). The model suggested that Tumour Inflammation Signature (TIS) and Personalised Immunotherapy Platform (PIP) PD-1 are informative signatures for predicting immunotherapy-response outcomes in advanced melanoma patients treated with anti-PD-1-based therapies. CONCLUSIONS: Overall, the outcome of this study confirms that singscore based on NanoString data is a feasible approach to produce reliable signature scores for determining patients' immune profiles and the potential clinical utility in biomarker implementation, as well as to conduct cross-platform comparisons, such as WTS.

Adjuvant radiotherapy after salvage surgery for melanoma recurrence in a node field following a previous lymph node dissection.

BACKGROUND AND OBJECTIVES: Adjuvant radiotherapy (RT) can be given to melanoma patients following salvage surgery for node field recurrence after a previous regional node dissection, but the value of this treatment strategy is poorly documented. This study evaluated long-term node field control and survival of patients treated in this way in an era before effective adjuvant systemic therapy became available. METHODS: Data for 76 patients treated between 1990 and 2011 were extracted from an institutional database. Baseline patient characteristics, treatment details and oncological outcomes were analysed. RESULTS: Adjuvant RT with conventional fractionation (median dose 48 Gy in 20 fractions) was given to 43 patients (57%) and hypofractionated RT (median dose 33 Gy in 6 fractions) to 33 patients (43%). The 5-year node field control rate was 70%, 5-year recurrence-free survival 17%, 5-year melanoma-specific survival 26% and 5-year overall survival 25%. CONCLUSIONS: Salvage surgery with adjuvant RT achieved node field control in 70% of melanoma patients with node field recurrence following a prior node dissection. However, disease progression at distant sites was common and survival outcomes were poor. Prospective data will be required to assess outcomes for contemporary combinations of surgery, adjuvant RT and systemic therapy.

Genomic Profiling of Metastatic Basal cell Carcinoma Reveals Candidate Drivers of Disease and Therapeutic Targets.

Basal cell carcinomas (BCCs) are human beings' most common malignant tumors. Most are easily managed by surgery or topical therapies, and metastasis is rare. Although BCCs can become locally advanced, metastatic BCCs are very uncommon and may be biologically distinct. We assessed the clinicopathologic characteristics of 17 patients with metastatic BCC and pursued whole-exome sequencing of tumor and germline DNA from 8 patients. Genomic profiling revealed aberrant activation of Hedgehog signaling and alterations in GLI transcriptional regulators and Notch and Hippo signaling. Matched local recurrences of primary BCCs and metastases from 3 patients provided evidence of a clonal origin in all cases. Mutations associated with YAP inhibition were found exclusively in 2 hematogenously-spread lung metastases, and metastatic BCCs were enriched for mutations in the YAP/TAZ-binding domain of TEAD genes. Accordingly, YAP/TAZ nuclear localization was associated with metastatic types and Hippo mutations, suggesting an enhanced oncogenic role in hematogenously-spread metastases. Mutations in RET, HGF, and phosphatidylinositol 3­kinase (PI3K)/protein kinase B (AKT) signaling were enriched compared with a cohort of low clinical-risk BCCs. Our results implicate Hippo and PI3K/AKT dysregulation in metastatic progression of BCCs, making these potential therapeutic targets in metastatic disease. The common clonal origin of matched recurrent and metastatic BCCs suggests that molecular profiling can assist in determining the nature/origin of poorly differentiated metastatic tumors of uncertain type. Genes and pathways enriched for mutations in this cohort are candidate drivers of metastasis and can be used to identify patients at high risk of metastasis who may benefit from aggressive local treatment and careful clinical follow-up.

Prognostic Significance and Management of Sentinel Nodes in the Triangular Intermuscular Space of Patients with Melanoma.

BACKGROUND: The clinical significance of sentinel nodes (SNs) in the triangular intermuscular space (TIS) of patients with melanoma is poorly understood. This study aimed to determine their incidence and positivity rate, and to report their management and patient outcomes. METHODS: This was a single-institution retrospective cohort study of patients with unilateral or bilateral TIS SNs on lymphoscintigraphy treated between 1992 and 2017. Recurrence-free survival was analyzed. RESULTS: Lymphoscintigraphy identified TIS SNs in 266 patients. They were bilateral in 17 patients. Of the 2296 patients with a melanoma on the upper back, 259 (11%) had TIS SNs. Procurement of SNs was not attempted in 122 (43%) of the 283 cases and failed in 11 cases (7%). An SN was successfully retrieved from the TIS in 145 patients (53%) and contained metastasis in 18 of 150 TIS SNs. This was the only positive SN in 12 patients (8%), upstaging all of them. Of the 18 patients with a positive SN in the TIS, 9 (50%) underwent completion axillary lymph node dissection, but no additional involved nodes were found in any of these patients. Recurrence in the TIS was observed in six patients (5%), none of whom had their TIS SN surgically pursued previously. CONCLUSIONS: Lymphoscintigraphy showed TIS SNs in 11% of patients with melanomas on their upper back. In such cases, retrieval of TIS SNs is required for accurate staging and to minimize the risk of TIS recurrence.

Higher polygenic risk for melanoma is associated with improved survival in a high ultraviolet radiation setting.

BACKGROUND: The role of germline genetic factors in determining survival from cutaneous melanoma (CM) is not well understood. OBJECTIVE: To perform a genome-wide association study (GWAS) meta-analysis of melanoma-specific survival (MSS), and test whether a CM-susceptibility polygenic risk score (PRS) is associated with MSS. METHODS: We conducted two Cox proportional-hazard GWAS of MSS using data from the Melanoma Institute Australia, a high ultraviolet (UV) radiation setting (MIA; 5,762 patients with melanoma; 800 melanoma deaths) and UK Biobank (UKB: 5,220 patients with melanoma; 241 melanoma deaths), and combined them in a fixed-effects meta-analysis. Significant (P < 5 × 10-8) results were investigated in the Leeds Melanoma Cohort (LMC; 1,947 patients with melanoma; 370 melanoma deaths). We also developed a CM-susceptibility PRS using a large independent GWAS meta-analysis (23,913 cases, 342,870 controls). The PRS was tested for an association with MSS in the MIA and UKB cohorts. RESULTS: Two loci were significantly associated with MSS in the meta-analysis of MIA and UKB with lead SNPs rs41309643 (G allele frequency 1.6%, HR = 2.09, 95%CI = 1.61-2.71, P = 2.08 × 10-8) on chromosome 1, and rs75682113 (C allele frequency 1.8%, HR = 2.38, 95%CI = 1.77-3.21, P = 1.07 × 10-8) on chromosome 7. While neither SNP replicated in the LMC, rs75682113 was significantly associated in the combined discovery and replication sets. After adjusting for age at diagnosis, sex and the first ten principal components, a one standard deviation increase in the CM-susceptibility PRS was associated with improved MSS in the discovery meta-analysis (HR = 0.88, 95% CI = 0.83-0.94, P = 6.93 × 10-5; I2 = 88%). However, this was only driven by the high UV setting cohort (MIA HR = 0.84, 95% CI = 0.78-0.90). CONCLUSION: We found two loci potentially associated with MSS. Increased genetic susceptibility to develop CM is associated with improved MSS in a high UV setting.

Diet-driven microbial ecology underpins associations between cancer immunotherapy outcomes and the gut microbiome.

The gut microbiota shapes the response to immune checkpoint inhibitors (ICIs) in cancer, however dietary and geographic influences have not been well-studied in prospective trials. To address this, we prospectively profiled baseline gut (fecal) microbiota signatures and dietary patterns of 103 trial patients from Australia and the Netherlands treated with neoadjuvant ICIs for high risk resectable metastatic melanoma and performed an integrated analysis with data from 115 patients with melanoma treated with ICIs in the United States. We observed geographically distinct microbial signatures of response and immune-related adverse events (irAEs). Overall, response rates were higher in Ruminococcaceae-dominated microbiomes than in Bacteroidaceae-dominated microbiomes. Poor response was associated with lower fiber and omega 3 fatty acid consumption and elevated levels of C-reactive protein in the peripheral circulation at baseline. Together, these data provide insight into the relevance of native gut microbiota signatures, dietary intake and systemic inflammation in shaping the response to and toxicity from ICIs, prompting the need for further studies in this area.

Comparative Genomics Provides Etiologic and Biological Insight into Melanoma Subtypes.

Melanoma is a cancer of melanocytes, with multiple subtypes based on body site location. Cutaneous melanoma is associated with skin exposed to ultraviolet radiation; uveal melanoma occurs in the eyes; mucosal melanoma occurs in internal mucous membranes; and acral melanoma occurs on the palms, soles, and nail beds. Here, we present the largest whole-genome sequencing study of melanoma to date, with 570 tumors profiled, as well as methylation and RNA sequencing for subsets of tumors. Uveal melanoma is genomically distinct from other melanoma subtypes, harboring the lowest tumor mutation burden and with significantly mutated genes in the G-protein signaling pathway. Most cutaneous, acral, and mucosal melanomas share alterations in components of the MAPK, PI3K, p53, p16, and telomere pathways. However, the mechanism by which these pathways are activated or inactivated varies between melanoma subtypes. Additionally, we identify potential novel germline predisposition genes for some of the less common melanoma subtypes. SIGNIFICANCE: This is the largest whole-genome analysis of melanoma to date, comprehensively comparing the genomics of the four major melanoma subtypes. This study highlights both similarities and differences between the subtypes, providing insights into the etiology and biology of melanoma. This article is highlighted in the In This Issue feature, p. 2711.

Unveiling the tumor immune microenvironment of organ-specific melanoma metastatic sites.

BACKGROUND: The liver is a known site of resistance to immunotherapy and the presence of liver metastases is associated with shorter progression-free and overall survival (OS) in melanoma, while lung metastases have been associated with a more favorable outcome. There are limited data available regarding the immune microenvironment at different anatomical sites of melanoma metastases. This study sought to characterize and compare the tumor immune microenvironment of liver, brain, lung, subcutaneous (subcut) as well as lymph node (LN) melanoma metastases. METHODS: We analyzed OS in 1924 systemic treatment-naïve patients with AJCC (American Joint Committee on Cancer) stage IV melanoma with a solitary site of organ metastasis. In an independent cohort we analyzed and compared immune cell densities, subpopulations and spatial distribution in tissue from liver, lung, brain, LN or subcut sites from 130 patients with stage IV melanoma. RESULTS: Patients with only liver, brain or bone metastases had shorter OS compared to those with lung, LN or subcutaneous and soft tissue metastases. Liver and brain metastases had significantly lower T-cell infiltration than lung (p=0.0116 and p=0.0252, respectively) and LN metastases (p=0.0116 and p=0.0252, respectively). T cells were further away from melanoma cells in liver than lung metastases (p=0.0335). Liver metastases displayed unique T-cell profiles, with a significantly lower proportion of programmed cell death protein-1+ T cells compared to all other anatomical sites (p<0.05), and a higher proportion of TIM-3+ T cells compared to LN (p=0.0004), subcut (p=0.0082) and brain (p=0.0128) metastases. Brain metastases had a lower macrophage density than subcut (p=0.0105), liver (p=0.0095) and lung (p<0.0001) metastases. Lung metastases had the highest proportion of programmed death ligand-1+ macrophages of the total macrophage population, significantly higher than brain (p<0.0001) and liver metastases (p=0.0392). CONCLUSIONS: Liver and brain melanoma metastases have a significantly reduced immune infiltrate than lung, subcut and LN metastases, which may account for poorer prognosis and reduced immunotherapy response rates in patients with liver or brain metastases. Increased TIM-3 expression in liver metastases suggests TIM-3 inhibitor therapy as a potential therapeutic opportunity to improve patient outcomes.