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Background: Immune checkpoint inhibitors have improved survival in advanced stage melanoma patients. Rates of new primary melanomas (NPM) in patients with prior melanoma have been reported to be as high as 12%. Little is currently known regarding the frequency or characteristics of NPMs occurring in melanoma patients treated with immune checkpoint inhibitors., Aim: To determine the frequency and describe clinicopathologic characteristics of NPMs diagnosed in patients during or after treatment with immune checkpoint inhibitors for metastatic melanoma., Methods: A retrospective analysis of prospectively collected data from the Melanoma Institute Australia and Westmead Hospital Dermatology databases. Clinicopathological data for the initial primary melanoma (IPM) and NPM were compared., Results: Between 2013-2017, 14 NPMs in 13 patients (out of a total of 1047) treated with checkpoint inhibitors were identified. NPMs were significantly thinner than the IPM (median Breslow thickness 0.35 mm vs 2.0 mm, P = 0.0003), less likely to be ulcerated (0/14 vs 6/13, P = 0.004) and less likely to have nodal metastases (0/14 vs 6/13, P = 0.004). NPMs were significantly more likely to be detected in the in-situ stage (6/14 vs 0/13, P = 0.0016)., Conclusion: NPMs are infrequent in patients treated with checkpoint inhibitors. When they occur, they are usually detected at an early stage and have features associated with a favourable prognosis, most likely reflecting close surveillance. Further study is required to determine long-term risk in patients achieving a durable response to immune checkpoint inhibitors, and to determine whether the immunotherapy itself influences both their development and biology., (© 2022 The Authors. Australasian Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Australasian College of Dermatologists.)

Background: Pembrolizumab prolongs progression-free and overall survival among patients with advanced melanoma and recurrence-free survival in resected stage III disease. KEYNOTE-716 assessed pembrolizumab as adjuvant therapy in patients with completely resected, high-risk, stage II melanoma. We report results from the planned first and second interim analyses for recurrence-free survival., Methods: In this double-blind, randomised, placebo-controlled phase 3 study, involving 160 academic medical centres and hospitals in 16 countries (Australia, Belgium, Brazil, Canada, Chile, France, Germany, Israel, Italy, Japan, Poland, South Africa, Spain, Switzerland, the UK, and the USA), patients aged 12 years or older with newly diagnosed, completely resected stage IIB or IIC melanoma (TNM stage T3b or T4 with a negative sentinel lymph node biopsy) were recruited. Eligible patients were randomly assigned (1:1), in blocks of four and stratified by T-category (3b, 4a, and 4b) and paediatric status (age 12-17 years vs ≥18 years), using an interactive response technology system to intravenous pembrolizumab 200 mg (2 mg/kg in paediatric patients) or placebo every 3 weeks for 17 cycles or until disease recurrence or unacceptable toxicity. All patients, clinical investigators, and analysts were masked to treatment assignment. The primary endpoint was investigator-assessed recurrence-free survival (defined as time from randomisation to recurrence or death) in the intention-to-treat (ITT) population (ie, all patients randomly assigned to treatment). The primary endpoint was met if recurrence-free survival was significantly improved for pembrolizumab versus placebo at either the first interim analysis (after approximately 128 patients had events) or second interim analysis (after 179 patients had events) under multiplicity control. Safety was assessed in all patients randomly assigned to treatment who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03553836, and is closed to accrual., Findings: Between Sept 23, 2018, and Nov 4, 2020, 1182 patients were screened, of whom 976 were randomly assigned to pembrolizumab (n=487) or placebo (n=489; ITT population). The median age was 61 years (IQR 52-69) and 387 (40%) patients were female and 589 (60%) were male. 874 (90%) of 976 patients were White and 799 (82%) were not Hispanic or Latino. 483 (99%) of 487 patients in the pembrolizumab group and 486 (99%) of 489 in the placebo group received assigned treatment. At the first interim analysis (data cutoff on Dec 4, 2020; median follow-up of 14·4 months [IQR 10·2-18·7] in the pembrolizumab group and 14·3 months [10·1-18·7] in the placebo group), 54 (11%) of 487 patients in the pembrolizumab group and 82 (17%) of 489 in the placebo group had a first recurrence of disease or died (hazard ratio [HR] 0·65 [95% CI 0·46-0·92]; p=0·0066). At the second interim analysis (data cutoff on June 21, 2021; median follow-up of 20·9 months [16·7-25·3] in the pembrolizumab group and 20·9 months [16·6-25·3] in the placebo group), 72 (15%) patients in the pembrolizumab group and 115 (24%) in the placebo group had a first recurrence or died (HR 0·61 [95% CI 0·45-0·82]). Median recurrence-free survival was not reached in either group at either assessment timepoint. At the first interim analysis, grade 3-4 treatment-related adverse events occurred in 78 (16%) of 483 patients in the pembrolizumab groups versus 21 (4%) of 486 in the placebo group. At the first interim analysis, four patients died from an adverse event, all in the placebo group (one each due to pneumonia, COVID-19-related pneumonia, suicide, and recurrent cancer), and at the second interim analysis, one additional patient, who was in the pembrolizumab group, died from an adverse event (COVID-19-related pneumonia). No deaths due to study treatment occurred., Interpretation: Pembrolizumab as adjuvant therapy for up to approximately 1 year for stage IIB or IIC melanoma resulted in a significant reduction in the risk of disease recurrence or death versus placebo, with a manageable safety profile., Funding: Merck Sharp & Dohme, a subsidiary of Merck & Co, Kenilworth, NJ, USA., Competing Interests: Declaration of interests JJL reports research funding to their institution for clinical studies from Merck Sharp & Dohme (MSD), AbbVie, Agios, Array, Astellas, AstraZeneca, Bristol-Myers Squibb, Corvus, Day One, EMD Serono, Fstar, Genmab, Ikena, Immatics, Incyte, Kadmon, KAHR, Macrogenics, Moderna, Nektar, Next Cure, Numab, Palleon, Pfizer, Replimune, Rubius, Servier, Scholar Rock, Synlogic, Takeda, Trishula, Tizona, and Xencor; membership on data safety monitoring boards for AbbVie and Immutep; membership on scientific advisory boards with no stock ownership or stock options for 7 Hills, Bright Peak, Fstar, Inzen, RefleXion, Xilioo, and with stock for Actym, Alphamab Oncology, Arch Oncology, Kanaph, Mavu, NeoTx, Onc.AI, Pyxis, and Tempest; compensation for consultancy with AbbVie, Alnylam, Bayer, Bristol-Myers Squibb, CheckMate, Codiak, Crown, Cstone, Day One, Eisai, EMD Serono, Flame, Genentech, Gilead, HotSpot, Kadmon, KQS, Janssen Ikena, Immunocore, Incyte, Macrogenics, Merck, Mersana, Nektar, Novartis, Pfizer, Regeneron, Ribon, Rublus, Silicon, Synlogic, Synthekine, TRex, Werewold, and Xencor; and a provisional patent for cancer immunotherapy (PCT/US18/36052: Microbiome Biomarkers for anti-PD-1/PD-L1 responsiveness: diagnostic, prognostic and therapeutic uses thereof). PR reports research funding to their institution from MSD and Pfizer and honoraria for lectures and advisory board participation from MSD, Bristol Myers Squibb, Novartis, Pierre Fabre, Sanofi, Merck, Philogen, and Blueprint Medicines. PQ reports research finding to their institution for clinical studies from MSD, and honoraria as consultant or advisor role from Bristol Myers Squibb, MSD, Merck, Novartis, Pierre Fabre, Sun Pharma, Sanofi-Regeneron, and Roche. MDV reports research finding to their institution for clinical studies from MSD and honoraria as consultant or advisor for Novartis, Bristol Myers Squibb, MSD, and Pierre Fabre. JM reports research funding to their institution for clinical studies from MSD; honoraria from Bristol Myers Squibb, MSD, Roche, Novartis, and Pierre Fabre; and consultant or advisor roles for Bristol Myers Squibb and MSD. VC-S reports research funding to their institution for clinical studies from MSD; reimbursement for travel and accommodation for medical congress from Bristol Myers Squibb and Pierre Fabre; and honoraria for advisory board participation from Novartis and Pierre Fabre. LdlCM reports research funding to their institution for clinical studies from Celgene, MSD, and Roche; reimbursement for travel expenses from Roche; and consultant or advisor roles for Bristol Myers Squibb, MSD, Novartis, and Roche. MAK reports research funding to their institution for clinical studies from MSD and MSD Australia; fees as speaker from Bristol Myers Squibb, Novartis, Merck Serono, and MSD Australia; and reimbursement for travel from Bristol Myers Squibb and Roche. DS reports research funding to their institution for clinical studies from Bristol Myers Squibb, MSD, Novartis, Amgen, and Array; grants paid to their institution from Bristol Myers Squibb, MSD, Novartis, Merck-EMD, Philogen, Pfizer, Array, InflarX, OncoSec, Replimune, Neracare, Nektar, SunPharma, Sandoz, and UltimoVacs; reimbursement for travel from Bristol Myers Squibb, Merck, Novartis, Merck-EMD, Pfizer, Pierre Fabre, InflarX, NeraCare, and Nektar; and non-financial support from Bristol Myers Squibb, MSD, Novartis, Merck-EMD, Pierre-Fabre, InFlarX, Neracare, Nektar, SunPharma, and Sandoz. GVL reports research funding to their institution for clinical studies from MSD and fees as a consultant or advisor from Aduro Biotech, Amgen, Arrary Biopharma, Boehringer Ingelheim International GmbH, Bristol Myers Squibb, Evaxion Biotech A/S, Hexal AG, Highlight Therapeutics S L, MSD, Novartis Pharma AG, OncoSec, Pierre Fabre, QBiotics Group, Regeneron Pharmaceuticals, SkylineDX BV, and Specialised Therapeutics Australia. PAA reports research funding to their institution for clinical studies from MSD, Bristol Myers Squibb, Roche-Genentech, Sanofi, and Pfizer and fees as a consultant or advisor from Bristol Myers Squibb, Roche-Genentech, MSD, Novartis, Merck Serono, Pierre Fabre, AstraZeneca, Sun Pharma, Sanofi, Idera, Sandoz, Immunocore, 4SC, Nektar, Italfarmaco, Boehringer Ingelheim, Eisai, Regeneron, Daiichi Sankyo, Pfizer, Oncosec, Nouscom, Lunaphore, Seagen, and ITeos. MM reports research funding to their institution for clinical studies from MSD and personal fees from MSD, Pierre Fabre, Novartis, Bristol Myers Squibb, and Sanofi. FDG and J-JG report research funding to their institutions for clinical studies from MSD. AH reports research funding to their institution for clinical studies from MSD and fees for advisory board membership from Novartis, Bristol Myers Squibb, and MSD. RD reports research funding to their institution for clinical studies from MSD and consulting or advisory roles with MSD, Novartis, Roche, Bristol Myers Squibb, Amgen, Takeda, Pierre Fabre, Sun Pharma, Sanofi, Catalym, Second Genome, Regeneron, Alligator, T3 Pharma, MaxiVAX SA, Pfizer, and touchIME. CR reports research funding to their institution for clinical studies from MSD and fees as a consultant or advisor for Amgen, AstraZeneca, Bristol Myers Squibb, MSD, Novartis, Pfizer, Pierre Fabre, Roche, and Sanofi. MSC reports research funding to their institution for clinical studies for MSD and honoraria for consulting from Bristol Myers Squibb, Eisia, IDEAYA Biosciences, Merck Serono, MSD, Novartis, Oncosec, Pierre Fabre, Qbiotics, Roche, and Sanofi. PM reports research funding to their institution for clinical studies from MSD, Amgen, Johnson & Johnson, Merck Serono, Novartis, Pfizer, Sanofi, and Sun Pharma; honoraria from Amgen, Bristol Myers Squibb, Merck, MSD, Novartis, Pierre Fabre, Roche/Genentech, and Sanofi; consulting or advisory roles for Amgen, Bristol Myers Squibb, Merck, MSD, Novartis, Pierre Fabre, Roche, and Sanofi; fees for speakers bureau from Amgen, Bristol Myers Squibb, MSD, Novartis, Roche, and Sanofi; and reimbursement for travel, accommodation, and expenses from Amgen, Bristol Myers Squibb, MSD, Novartis, Pierre Fabre, Roche, Sanofi, and Sun Pharma. AP reports research funding to their institution for clinical studies from MSD; fees for consulting or advisory roles from Novartis; and fees for speakers bureau from Bristol Myers Squibb. VKS reports research funding to their institution for clinical studies from MSD and Neogene Therapeutic and fees for participation in independent data safety monitoring committees and participation in advisory boards from Bristol Myers Squibb, Eisai, Novartis, Merck, Regeneron, and Replimune. RAS reports research funding to their institution from MSD and fees for professional services from F Hoffmann-La Roche, Evaxion, Provectus Biopharmaceuticals Australia, Qbiotics, Novartis, MSD, NeraCare, AMGEN, Bristol Myers Squibb, Myriad Genetics, and GSK. RAS is supported by an Australian National Health and Medical Research Council Practitioner Fellowship (APP1141295). JMK reports research funding to their institution from MSD, Amgen, Bristol Myers Squibb, Checkmate Pharmaceuticals, Immunocore, Iovance Biotherapies, Novartis Pharmaceuticals, Castle Biosciences, and Merck; personal fees from Amgen, Ankyra Therapeutics, Axio Research/Instil Bio, Bristol Myers Squibb, Checkmate Pharmaceuticals, DermTech, Elsevier, Harbour BioMed, Immunocore, Iovance Biotherapies, Istari Oncology, Millenium Pharm/Takeda Pharm, Natera, Novartis Pharmaceutical, OncoCyte Corporation, OncoSec Medical, Pfizer, Scopus BioPharma, Merck, Becker Pharmaceutical Consulting, Fenix Group International, Intellisphere LLC/Cancer Network, IQVIA, Replimune, and SR One Capital Managment. KC, SJD, SA, and NI are employees of and own stock in MSD. AMME reports research funding to their institution for clinical studies from MSD; fees for advisory board membership for Merck, Agenus, Biocad, BioInvent, BioNTech, Bristol Myers Squibb, CatalYm, Ellipses, Galecto, GSK, IO Biotech, ISA Pharmaceuticals, Merck, MSD, Nektar, Novartis, Pfizer, Sellas, SkylineDX, TigaTx, and TxDiscovery; personal fees for independent data monitoring committee for Biocad, GSK, Pfizer, and Novartis; fees for participation in speakers bureau from Biocad, Bristol Myers Squibb, and Merck; and equity in IO Biotech, SkylineDX., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Context: The significance of thyroid peroxidase (TPOAb) and thyroglobulin antibody (TgAb) in the pathogenesis of thyroid immune-related adverse events (irAEs) is unknown., Objective: To characterize the association of anti-thyroid antibodies with the development of thyroid immune related adverse events., Methods: A retrospective cohort study was conducted of patients with melanoma receiving immune checkpoint inhibitor (ICI) treatment. TPOAb, TgAb, and interleukin-6 (IL-6) were measured retrospectively using tumor-banked samples at baseline and at time of diagnosis of a thyroid irAE. In euthyroid patients (without thyroid irAEs) measures were repeated 30 to 60 days after ICI commencement, which was similar to the median time to onset of thyroid irAEs in other patients., Results: A total of 122 patients were included-31 remained euthyroid, 47 developed subclinical thyrotoxicosis, 37 developed overt thyrotoxicosis, and 7 developed overt hypothyroidism without preceding thyrotoxicosis. Baseline elevation of TPOAb or TgAb was present in 19 (16%) and 28 (23%) patients, respectively. Positive TPOAb or TgAb at baseline was 97% and 100% specific for eventual development of a thyroid irAE, respectively. During ICI treatment, overt thyrotoxicosis, but not other subtypes of thyroid irAE, was associated with statistically significant increases in the titer of TgAb and TPOAb. Baseline IL-6 levels were not associated with thyroid irAE onset but statistically significantly increased during treatment in patients who developed overt hypothyroidism., Conclusions: TPOAb and TgAb positivity at baseline was more prevalent in patients who developed thyroid irAEs. Statistically significant increases or new antibody positivity was observed in association with overt thyrotoxicosis. TPOAb and TgAb positivity or increases during ICI treatment may be a useful biomarker to identify patients at increased risk of thyroid irAEs, particularly overt thyrotoxicosis., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Detection of melanoma mutations using circulating tumor DNA (ctDNA) is a potential alternative to using genomic DNA from invasive tissue biopsies. To date, mutations in the GC-rich TERT promoter region, which is commonly mutated in melanoma, have been technically difficult to detect in ctDNA using next-generation sequencing (NGS) panels. In this study, we developed a custom melanoma NGS panel for detection of ctDNA, which encompasses the top 15 gene mutations in melanoma including the TERT promoter. We analyzed 21 stage III and IV melanoma patient samples who were treatment-naïve or on therapy. The overall detection rate of the custom panel, based on BRAF / NRAS / TERT promoter mutations, was 14/21 (67%) patient samples which included a TERT C250T mutation in one BRAF and NRAS mutation negative sample. A BRAF or NRAS mutation was detected in the ctDNA of 13/21 (62%) patients while TERT promoter mutations were detected in 10/21 (48%) patients. Co-occurrence of TERT promoter mutations with BRAF or NRAS mutations was found in 9/10 (90%) patients. The custom ctDNA panel showed a concordance of 16/21 (76%) with tissue based-detection and included 12 BRAF / NRAS mutation positive and 4 BRAF/NRAS mutation negative patients. The ctDNA mutation detection rate for stage IV was 12/16 (75%) and for stage III was 1/5 (20%). Based on BRAF , NRAS and TERT promoter mutations, the custom melanoma panel displayed a limit of detection of ~0.2% mutant allele frequency and showed significant correlation with droplet digital PCR. For one patient, a novel MAP2K1 H119Y mutation was detected in an NRAS/BRAF/TERT promoter mutation negative background. To increase the detection rate to >90% for stage IV melanoma patients, we plan to expand our custom panel to 50 genes. This study represents one of the first to successfully detect TERT promoter mutations in ctDNA from cutaneous melanoma patients using a targeted NGS panel., Competing Interests: GL receives consultant service fees from Amgen, BMS, Array, Pierre-Fabre, Novartis, Merck Sharp & Dohme (MSD), Qbiotics, Roche and Sandoz. AM is an advisory board member for BMS, MSD, Novartis, Roche, Pierre Fabre and Qbiotics. MC is an advisory board member for MSD, BMS, Novartis, Pierre-Fabre, Roche and Amgen. RAS has received fees for professional services from Evaxion, Provectus Biopharmaceuticals Australia, Qbiotics Group Limited, Novartis Pharma AG, MSD Sharp & Dohme (Australia), NeraCare, AMGEN Inc., Bristol-Myers Squibb, Novartis Pharmaceuticals Australia Pty Limited, Myriad Genetics GmbH, GlaxoSmithKline Australia. RPMS has received honoraria for advisory board participation from MSD, Novartis and Qbiotics and speaking honoraria from BMS. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Diefenbach, Lee, Stewart, Menzies, Carlino, Saw, Stretch, Long, Scolyer and Rizos.)

There is increasing evidence that nerve growth factor (NGF) and its receptors, the neurotrophic receptor tyrosine kinase 1 (NTRK1/TrkA), the common neurotrophin receptor (NGFR/p75NTR) and the membrane receptor sortilin, participate in cancer growth. In melanoma, there have been some reports suggesting that NGF, TrkA and p75NTR are dysregulated, but the expression of the NGF precursor (proNGF) and its membrane receptor sortilin is unknown. In this study, we investigated the expression of NGF, proNGF, TrkA, p75NTR and sortilin by immunohistochemistry in a series of human tissue samples (n = 100), including non-cancerous nevi (n = 20), primary melanomas (n = 40), lymph node metastases (n = 20) and distant metastases (n = 20). Immunostaining was digitally quantified and revealed NGF and proNGF were expressed in all nevi and primary melanomas, and that the level of expression decreased from primary tumors to melanoma metastases (p = 0.0179 and p < 0.0001, respectively). Interestingly, TrkA protein expression was high in nevi and thin primary tumors but was strongly downregulated in thick primary tumors (p < 0.0001) and metastases (p < 0.0001). While p75NTR and sortilin were both expressed in most nevi and melanomas, there was no significant difference in expression between them. Together, these results pointed to a downregulation of NGF/ProNGF and TrkA in melanoma, and thus did not provide evidence to support the use of anti-proNGF/NGF or anti-TrkA therapies in advanced and metastatic forms of melanoma.

Background: Patients with BRAF -mutant and wild-type melanoma have different response rates to immune checkpoint blockade therapy. However, the reasons for this remain unknown. To address this issue, we investigated the precise immune composition resulting from BRAF mutation in treatment-naive melanoma to determine whether this may be a driver for different response to immunotherapy., Methods: In this study, we characterized the treatment-naive immune context in patients with BRAF -mutant and BRAF wild-type ( BRAF -wt) melanoma using data from single-cell RNA sequencing, bulk RNA sequencing, flow cytometry and immunohistochemistry (IHC)., Results: In single-cell data, BRAF -mutant melanoma displayed a significantly reduced infiltration of CD8 + T cells and macrophages but also increased B cells, natural killer (NK) cells and NKT cells. We then validated this finding using bulk RNA-seq data from the skin cutaneous melanoma cohort in The Cancer Genome Atlas and deconvoluted the data using seven different algorithms. Interestingly, BRAF -mutant tumors had more CD4 + T cells than BRAF -wt samples in both primary and metastatic cohorts. In the metastatic cohort, BRAF -mutant melanoma demonstrated more B cells but less CD8 + T cell infiltration when compared with BRAF -wt samples. In addition, we further investigated the immune cell infiltrate using flow cytometry and multiplex IHC techniques. We confirmed that BRAF -mutant melanoma metastases were enriched for CD4 + T cells and B cells and had a co-existing decrease in CD8 + T cells. Furthermore, we then identified B cells were associated with a trend for improved survival (p=0.078) in the BRAF -mutant samples and Th2 cells were associated with prolonged survival in the BRAF -wt samples., Conclusions: In conclusion, treatment-naive BRAF -mutant melanoma has a distinct immune context compared with BRAF -wt melanoma, with significantly decreased CD8 + T cells and increased B cells and CD4 + T cells in the tumor microenvironment. These findings indicate that further mechanistic studies are warranted to reveal how this difference in immune context leads to improved outcome to combination immune checkpoint blockade in BRAF -mutant melanoma., Competing Interests: Competing interests: RAS has received fees for professional services from Qbiotics, Novartis, Merck Sharp & Dohme, NeraCare, AMGEN, Bristol-Myers Squibb, Myriad Genetics, GlaxoSmithKline. GL has received professional consulting fees from Aduro Biotech, Amgen, Array Biopharma, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Highlight Therapeutics SL, Merck Sharpe & Dohme, Novartis Pharma AG, Pierre Fabre, QBiotics Group, Regeneron Pharmaceuticals, SkylineDX BV (all unrelated to this work). PJN received research funding from Roche/Genentech, BMS, MSD, Allergan, Compugen, Crispr Therapeutics. The other authors declare no conflicts of interest., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Importance: Neoadjuvant checkpoint inhibition in patients with high-risk stage III melanoma shows high pathologic response rates associated with a durable relapse-free survival. Whether a therapeutic lymph node dissection (TLND) can be safely omitted when a major pathologic response in the largest lymph node metastasis at baseline (index lymph node; ILN) is obtained is currently being investigated. A previous small pilot study (n = 12) showed that the response in the ILN may be representative of the pathologic response in the entire TLND specimen., Objective: To assess the concordance of response between the ILN and the total lymph node bed in a larger clinical trial population., Design, Setting, and Participants: Retrospective pathologic response analysis of a multicenter clinical trial population of patients from the randomized Study to Identify the Optimal Adjuvant Combination Scheme of Ipilimumab and Nivolumab in Melanoma Patients (OpACIN) and Optimal Neo-Adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) trials. Included patients were treated with 6 weeks neoadjuvant ipilimumab plus nivolumab. Patient inclusion into the trials was conducted from August 12, 2015, to October 24, 2016 (OpACIN), and November 24, 2016, and June 28, 2018 (OpACIN-neo). Data were analyzed from April 1, 2020, to August 31, 2021., Main Outcomes and Measures: Concordance of the pathologic response between the ILN and the TLND tumor bed. The pathologic response of the ILN was retrospectively assessed according to the International Neoadjuvant Melanoma Consortium criteria and compared with the pathologic response of the entire TLND specimen., Results: A total of 82 patients treated with neoadjuvant ipilimumab and nivolumab followed by TLND (48 [59%] were male; median age, 58.5 [range, 18-80] years) were included. The pathologic response in the ILN was concordant with the entire TLND specimen response in 81 of 82 patients (99%) and in 79 of 82 patients (96%) concordant when comparing the ILN response with the response in every individual lymph node. In the single patient with a discordant response, the ILN response (20% viable tumor, partial pathologic response) underestimated the entire TLND specimen response (5% viable, near-complete pathologic response). Two other patients each had 1 small nonindex node that contained 80% viable tumor (pathologic nonresponse) whereas all other lymph nodes (including the ILN) showed a partial pathologic response. In these 2 patients, the risk of regional relapse might potentially have been increased if TLND had been omitted., Conclusions and Relevance: The results of this study suggest that the pathologic response of the ILN may be considered a reliable indicator of the entire TLND specimen response and may support the ILN response-directed omission of TLND in a prospective trial.

Oncogenic alterations to DNA are not transforming in all cellular contexts 1,2 . This may be due to pre-existing transcriptional programmes in the cell of origin. Here we define anatomic position as a major determinant of why cells respond to specific oncogenes. Cutaneous melanoma arises throughout the body, whereas the acral subtype arises on the palms of the hands, soles of the feet or under the nails 3 . We sequenced the DNA of cutaneous and acral melanomas from a large cohort of human patients and found a specific enrichment for BRAF mutations in cutaneous melanoma and enrichment for CRKL amplifications in acral melanoma. We modelled these changes in transgenic zebrafish models and found that CRKL-driven tumours formed predominantly in the fins of the fish. The fins are the evolutionary precursors to tetrapod limbs, indicating that melanocytes in these acral locations may be uniquely susceptible to CRKL. RNA profiling of these fin and limb melanocytes, when compared with body melanocytes, revealed a positional identity gene programme typified by posterior HOX13 genes. This positional gene programme synergized with CRKL to amplify insulin-like growth factor (IGF) signalling and drive tumours at acral sites. Abrogation of this CRKL-driven programme eliminated the anatomic specificity of acral melanoma. These data suggest that the anatomic position of the cell of origin endows it with a unique transcriptional state that makes it susceptible to only certain oncogenic insults., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Purpose: Currently, there are no robust biomarkers that predict immunotherapy outcomes in metastatic melanoma. We sought to build multivariable predictive models for response and survival to anti-programmed cell death protein 1 (anti-PD-1) monotherapy or in combination with anticytotoxic T-cell lymphocyte-4 (ipilimumab [IPI]; anti-PD-1 ± IPI) by including routine clinical data available at the point of treatment initiation., Methods: One thousand six hundred forty-four patients with metastatic melanoma treated with anti-PD-1 ± IPI at 16 centers from Australia, the United States, and Europe were included. Demographics, disease characteristics, and baseline blood parameters were analyzed. The end points of this study were objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). The final predictive models for ORR, PFS, and OS were determined through penalized regression methodology (least absolute shrinkage and selection operator method) to select the most significant predictors for all three outcomes (discovery cohort, N = 633). Each model was validated internally and externally in two independent cohorts (validation-1 [N = 419] and validation-2 [N = 592]) and nomograms were created., Results: The final model for predicting ORR (area under the curve [AUC] = 0.71) in immunotherapy-treated patients included the following clinical parameters: Eastern Cooperative Oncology Group Performance Status, presence/absence of liver and lung metastases, serum lactate dehydrogenase, blood neutrophil-lymphocyte ratio, therapy (monotherapy/combination), and line of treatment. The final predictive models for PFS (AUC = 0.68) and OS (AUC = 0.77) included the same variables as those in the ORR model (except for presence/absence of lung metastases), and included presence/absence of brain metastases and blood hemoglobin. Nomogram calculators were developed from the clinical models to predict outcomes for patients with metastatic melanoma treated with anti-PD-1 ± IPI., Conclusion: Newly developed combinations of routinely collected baseline clinical factors predict the response and survival outcomes of patients with metastatic melanoma treated with immunotherapy and may serve as valuable tools for clinical decision making., Competing Interests: Inês Pires da SilvaConsulting or Advisory Role: MSDSpeakers' Bureau: Roche, Novartis, Bristol Myers SquibbTravel, Accommodations, Expenses: Roche, Bristol Myers Squibb Jennifer L. McQuadeHonoraria: Merck, Bristol Myers Squibb, RocheConsulting or Advisory Role: Bristol Myers Squibb, Roche Pharma AGTravel, Accommodations, Expenses: Merck Selma UgurelHonoraria: Bristol Myers Squibb, Merck Sharp & Dohme, Roche, Novartis, Merck SeronoConsulting or Advisory Role: Bristol Myers Squibb, Roche, Merck SeronoResearch Funding: Bristol Myers Squibb (Inst), Merck Serono (Inst)Travel, Accommodations, Expenses: Bristol Myers Squibb, Merck Sharp & Dohme, Roche, Novartis, Pierre Fabre Rudolf HerbstEmployment: Helios Kliniken Jochen UtikalStock and Other Ownership Interests: BioNTech, Moderna Therapeutics, Pfizer, Merck, SanofiHonoraria: Bristol Myers Squibb, Novartis, MSD Oncology, Roche, Pierre Fabre, SanofiConsulting or Advisory Role: Bristol Myers Squibb, Roche, MSD Oncology, Novartis, Pierre Fabre, Amgen, SanofiResearch Funding: Apogenix (Inst), Noxxon Pharma (Inst), Elsalys Biotech (Inst), TILT Biotherapeutics (Inst)Travel, Accommodations, Expenses: MSD Oncology, Roche, Novartis, Pierre Fabre, Bristol Myers Squibb, Amgen, Sanofi Claudia PföhlerHonoraria: Bristol Myers Squibb, Novartis, Roche, MSD, Merck Serono, Sun Pharma, Amgen, AbbVieConsulting or Advisory Role: Bristol Myers Squibb Foundation, Novartis, MSD, Roche, Sanofi, Allergy Therapeutics, Merck SeronoTravel, Accommodations, Expenses: Bristol Myers Squibb, Novartis, MSD, Roche, Pierre Fabre, Celgene, AbbVie, Merck Serono Patrick TerheydenHonoraria: Bristol Myers Squibb, Novartis, Roche, CureVac, Merck Serono, MSD OncologyConsulting or Advisory Role: Bristol Myers Squibb, Novartis, Pierre Fabre, Roche, Sanofi, Merck KGaA, 4SC, AlmirallTravel, Accommodations, Expenses: Bristol Myers Squibb, Pierre Fabre Michael WeichenthalHonoraria: Merck Sharp & Dohme, Roche, Novartis, Bristol Myers Squibb, SanofiConsulting or Advisory Role: Merck Sharp & Dohme, Roche, Novartis, Bristol Myers Squibb, Sun Pharma, Sanofi, Pierre FabreResearch Funding: Merck Sharp & Dohme (Inst), Millennium (Inst), Bristol Myers Squibb (Inst), Johnson & Johnson (Inst), Novartis (Inst) Ralf GutzmerHonoraria: Bristol Myers Squibb, Merck Sharp & Dohme, Roche/Genentech, Novartis, Merck Serono, Almirall Hermal GmbH, Amgen, Sun Pharma, Pierre Fabre, Sanofi/Regeneron, ImmunocoreConsulting or Advisory Role: Bristol Myers Squibb, Merck Sharp & Dohme, Roche/Genentech, Novartis, Almirall Hermal GmbH, 4SC, Amgen, Pierre Fabre, Merck Serono, Sun Pharma, Sanofi, ImmunocoreResearch Funding: Pfizer (Inst), Novartis (Inst), Johnson & Johnson (Inst), Amgen (Inst), Merck Serono (Inst), Sun Pharma (Inst), Sanofi (Inst)Travel, Accommodations, Expenses: Bristol Myers Squibb, Roche, Merck Serono, Pierre Fabre, Sun Pharma Peter MohrHonoraria: Bristol Myers Squibb, Merck Sharp & Dohme, Roche/Genentech, Novartis, Amgen, Pierre Fabre, Merck, SanofiConsulting or Advisory Role: Bristol Myers Squibb, Merck Sharp & Dohme, Novartis, Amgen, Roche, Merck, Pierre Fabre, SanofiSpeakers' Bureau: Novartis, Roche, Bristol Myers Squibb, Merck Sharp & Dohme, Amgen, SanofiResearch Funding: Merck Sharp & Dohme (Inst), Bristol Myers Squibb (Inst), Novartis (Inst)Travel, Accommodations, Expenses: Bristol Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre Fabre, Amgen, Roche, Sun Pharma, Sanofi Jessica L. SmithHonoraria: Pierre FabreTravel, Accommodations, Expenses: MSD Oncology Richard A. ScolyerEmployment: Royal Prince Alfred HospitalHonoraria: GlaxoSmithKline, Harvard Medical School, Wake Forest School of MedicineConsulting or Advisory Role: Bristol Myers Squibb GesmbH (Austria), Bristol Myers Squibb SA (Switzerland), GlaxoSmithKline, Merck Sharp & Dohme, NeraCare GmbH, Novartis Australia, Amgen, Myriad Genetics, MSD Sharp & Dohme (Australia) Pty Limited, Novartis, QBiotics, Provectus Biopharmaceuticals Australia, Evaxion BioTech A/S, Novartis Pharmaceuticals Australia Pty Limited, RocheResearch Funding: The Ainsworth Foundation (Inst), National Health and Medical Research Council, Melanoma Research Alliance (MRA) GrantTravel, Accommodations, Expenses: Bristol Myers Squibb, Novartis AustraliaUncompensated Relationships: Melanoma Institute Australia Ana M. AranceConsulting or Advisory Role: BMS, Roche, Novartis, Pierre Fabre, MSD, Merck, SanofiSpeakers' Bureau: Pierre Fabre, Novartis, MSD, BMS, Roche, Merck, SanofiResearch Funding: Pierre Fabre, Novartis, Roche, BMS, MSD, Merck, Sanofi, AmgenTravel, Accommodations, Expenses: BMS, MSD, Novartis, Pierre Fabre, Roche, Merck, Sanofi Lisa PickeringConsulting or Advisory Role: Pfizer, Ipsen, BMS, Eisai, MSD Oncology, NovartisSpeakers' Bureau: Pfizer, BMSResearch Funding: NIHR (Inst), Rosetrees Trust (Inst), Kidney and melanoma cancer fund of RMH charity (Inst) James LarkinHonoraria: Bristol Myers Squibb, GlaxoSmithKline, Pfizer, Novartis, Roche/Genentech, Incyte, iOnctura, Merck Serono, Eisai, Dynavax Technologies, Cancer Research UK, touchIME, touchEXPERTSConsulting or Advisory Role: Bristol Myers Squibb, GlaxoSmithKline, Pfizer, Novartis, Boston Biomedical, Incyte, iOnctura, Iovance Biotherapeutics, Immunocore, YKT Corporation, Apple Tree PartnersResearch Funding: Pfizer (Inst), Novartis (Inst), MSD (Inst), Bristol Myers Squibb (Inst), Achilles Therapeutics (Inst), Roche (Inst), Nektar (Inst), Covance (Inst), Immunocore (Inst), AVEO (Inst), Pharmacyclics (Inst)Travel, Accommodations, Expenses: Bristol Myers Squibb, Pfizer, Novartis, Roche/Genentech, AstraZeneca, Incyte, GlaxoSmithKline, Pierre Fabre, Merck Serono, iOnctura, British Uro-Oncology Group (BUG), ESMO, National Cancer Research Institute (NCRI), EUSA Pharma, Syneos Health, Kidney Cancer Association, Bioevents, MedConcept, RV Mais Paul LoriganHonoraria: Novartis, Pierre Fabre, Merck, BMS, MSD, NeraCare GmbH, Amgen, Roche, Oncology Education, NektarConsulting or Advisory Role: Merck Sharp & Dohme, Bristol Myers Squibb, Amgen, Pierre Fabre, Novartis, NektarSpeakers' Bureau: Merck Sharp & Dohme, Novartis, Bristol Myers Squibb, Pierre FabreResearch Funding: BMS, Pierre FabreTravel, Accommodations, Expenses: Merck Sharp & Dohme, Bristol Myers Squibb Christian U. BlankStock and Other Ownership Interests: Uniti Cars, ImmageneConsulting or Advisory Role: Roche/Genentech (Inst), MSD Oncology (Inst), Bristol Myers Squibb (Inst), Novartis (Inst), GlaxoSmithKline (Inst), Pfizer (Inst), AstraZeneca (Inst), Lilly (Inst), Pierre Fabre (Inst), GenMab (Inst), Third Rock VenturesResearch Funding: Bristol Myers Squibb (Inst), Novartis (Inst), NanoString Technologies (Inst)Travel, Accommodations, Expenses: Bristol Myers Squibb Dirk SchadendorfHonoraria: Roche/Genentech, Novartis, Bristol Myers Squibb, Merck Sharp & Dohme, Immunocore, Merck Serono, Array BioPharma, Pfizer, Pierre Fabre, Philogen, Regeneron, 4SC, Sanofi/Regeneron, NeraCare GmbH, Sun Pharma, InflarxGmbH, Ultimovacs, SandozConsulting or Advisory Role: Roche/Genentech, Novartis, Bristol Myers Squibb, Merck Sharp & Dohme, Merck Serono, 4SC, Pierre Fabre, Sanofi/Regeneron, NektarSpeakers' Bureau: Bristol Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre Fabre, Sanofi/Regeneron, Merck KGaAResearch Funding: Bristol Myers Squibb (Inst), Novartis (Inst), Roche (Inst), MSD Oncology (Inst), Array BioPharma/Pfizer (Inst)Travel, Accommodations, Expenses: Roche/Genentech, Bristol Myers Squibb, Merck Serono, Novartis, Merck Sharp & Dohme, Pierre Fabre, Sanofi/Regeneron Michael A. DaviesConsulting or Advisory Role: Genentech/Roche, Novartis, Bristol Myers Squibb, NanoString Technologies, Array BioPharma, Apexigen, ABM Therapeutics, Pfizer, EisaiResearch Funding: GlaxoSmithKline (Inst), Genentech/Roche (Inst), AstraZeneca (Inst), Merck (Inst), Oncothyreon (Inst), Myriad Genetics (Inst), Sanofi (Inst), Pfizer (Inst) Matteo S. CarlinoHonoraria: Bristol Myers Squibb, MSD, NovartisConsulting or Advisory Role: Bristol Myers Squibb, MSD, Amgen, Novartis, Pierre Fabre, Roche, IDEAYA Biosciences, Sanofi, Merck Serono, Regeneron, QBiotics, Nektar, Eisai, OncoSec Douglas B. JohnsonConsulting or Advisory Role: Bristol Myers Squibb, Merck, Novartis, Janssen, Iovance Biotherapeutics, Catalyst Pharmaceuticals, Oncosec, Pfizer, Mosaic ImmunoEngineering, TargovaxResearch Funding: Incyte, Bristol Myers SquibbPatents, Royalties, Other Intellectual Property: Intellectual property and patents pending surrounding use of MHC-II and response to immune therapy Georgina V. LongHonoraria: BMS, Pierre FabreConsulting or Advisory Role: Aduro Biotech, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Hexal, Highlight Therapeutics, Merck Sharpe & Dohme, Novartis, OncoSec, Pierre Fabre, QBiotics, Regeneron, SkylineDx, Specialised Therapeutics, Array BioPharma, Evaxion Biotech A/S, Evaxion Biotech A/S, SkylineDX B.V Alexander M. MenziesConsulting or Advisory Role: MSD Oncology, Novartis, Pierre Fabre, Bristol Myers Squibb, Roche, QBioticsNo other potential conflicts of interest were reported.

Over the last 10 years, with the development of culture-free bacterial identification techniques, understanding of how the microbiome influences diseases has increased exponentially and has highlighted potential opportunities for its use as a diagnostic biomarker and interventional target in many diseases including malignancy. Initial research focused on the faecal microbiome since it contains the densest bacterial populations and many other mucosal sites, such as the lungs, were until recently thought to be sterile. However, in recent years, it has become clear that the lower airways are home to a dynamic bacterial population sustained by the migration and elimination of microbes from the gastrointestinal and upper airway tracts. As in the gut, the lung microbiome plays an important role in regulating mucosal immunity and maintaining the balance between immune tolerance and inflammation. Studies to date have all shown that the lung microbiome undergoes significant changes in the setting of pulmonary disease. In lung cancer, animal models and small patient cohort studies have suggested that microbiome dysbiosis may not only impact tumour progression and response to therapy, particularly immunotherapy, but also plays a key role in cancer pathogenesis by influencing early carcinogenic pathways. These early results have led to concerted efforts to identify microbiome signatures that represent diagnostic biomarkers of early-stage disease and to consider modulation of the lung microbiome as a potential therapeutic strategy. Lung microbiome research is in its infancy and studies to date have been small, single centre with significant methodological variation. Large, multicentre longitudinal studies are needed to establish the clinical potential of this exciting field., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Wide local excision (WLE) to achieve adequate clearance margins is the standard initial definitive treatment for patients with biopsy-proven primary cutaneous melanoma. Residual melanoma in WLE specimens after prior complete excision-biopsy (CEB) is reported in 0-6.3% of cases. However, studies evaluating the prevalence, clinicopathological features and relevance of persistent disease in WLE specimens are limited. This study sought to determine the frequency of and clinicopathological characteristics associated with residual melanoma in WLE specimens performed after a CEB of primary cutaneous or acral melanoma (in situ or invasive) with clinically and histologically tumour-free margins, and assess its relevance. A review of the research database and pathology archives of a large Australian tertiary referral melanoma treatment centre was performed. Eligible patients were those for whom a definitive WLE was performed after CEB of a primary melanoma (in situ or invasive) with negative clinical and histological margins, between May 2013 and May 2015. All partial biopsies were excluded. Of 640 eligible patients, 510 (79.7%) had invasive melanoma and 130 (20.3%) had melanoma in situ. Residual disease was identified in 20 cases (20/640, 3.1%), of which three (15%) were melanoma in situ on CEB and 17 (85%) were invasive melanoma. On univariate analysis, the presence of residual disease in WLE specimens was associated with lentigo maligna (LM)/LM melanoma (LMM) subtype [odds ratio (OR) 10.33; 95% confidence interval (CI) 2.84-37.54; p=0.004], nodular melanoma (NM) subtype (OR 4.92; 95% CI 1.53-15.85; p=0.0076) and, for invasive tumours, higher tumour mitotic rate (mean 7.7, SD 7.51 vs 3.4, SD 4.83; OR 1.11; 95% CI 1.04-1.18; p=0.0014). Breslow thickness >4 mm was associated with a higher risk of residual disease (OR 7.30; 95% CI 1.88, 28.26; p=0.004). Cases with residual disease had primary tumours with a significantly larger diameter (median 14 mm, range 4-25) than those without residual disease (median 9 mm, range 2-60), (OR 1.07; 95% CI 1.03-1.11; p≤0.001) and were also more likely to be amelanotic (38% vs 14%), (OR 3.69; 95% CI 1.17, 11.60; p=0.026). Residual disease was associated with assessment of >3 slides of tissue (OR 6.98; 95% CI 1.54-31.62; p=0.0118) and complete blocking of the scar (OR 31.69; 95% CI 3.98-252.21; p=0.0011). Residual melanoma in WLE specimens is an infrequent occurrence. Risk factors for residual disease are LM/LMM and NM melanoma subtypes, higher mitotic rate, larger lesion diameter and amelanosis. Tumours with these features warrant more extensive pathological sampling. WLE after CEB for melanoma remains an important procedure to reduce local recurrence; however, limited pathological sampling of the WLE scar is probably appropriate for cases lacking high risk features., (Crown Copyright © 2021. Published by Elsevier B.V. All rights reserved.)

Targeted therapy (BRAF inhibitor plus MEK inhibitor) is now among the possible treatment options for patients with BRAF mutation-positive stage III or stage IV melanoma. This makes prompt BRAF mutation testing an important step in the management of patients diagnosed with stage III or IV melanoma; one that can help better ensure that the optimal choice of systemic treatment is initiated with minimal delay. This article offers guidance about when and how BRAF mutation testing should be conducted when patients are diagnosed with melanoma in Australia. Notably, it recommends that pathologists reflexively order BRAF mutation testing whenever a patient is found to have American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) stage III or IV melanoma (i.e., any metastatic spread beyond the primary tumour) and that patient's BRAF mutation status is hitherto unknown, even if BRAF mutation testing has not been specifically requested by the treating clinician (in Australia, Medicare-subsidised BRAF V600 mutation testing does not need to be requested by the treating clinician). When performed in centres with appropriate expertise and experience, immunohistochemistry (IHC) using the anti-BRAF V600E monoclonal antibody (VE1) can be a highly sensitive and specific means of detecting BRAF V600E mutations, and may be used as a rapid and relatively inexpensive initial screening test. However, VE1 immunostaining can be technically challenging and difficult to interpret, particularly in heavily pigmented tumours; melanomas with weak, moderate or focal BRAF V600E immunostaining should be regarded as equivocal. It must also be remembered that other activating BRAF V600 mutations (including BRAF V600K ), which account for ∼10-20% of BRAF V600 mutations, are not detected with currently available IHC antibodies. For these reasons, if available and practicable, we recommend that DNA-based BRAF mutation testing always be performed, regardless of whether IHC-based testing is also conducted. Advice about tissue/specimen selection for BRAF mutation testing of patients diagnosed with stage III or IV melanoma is also offered in this article; and potential pitfalls when interpreting BRAF mutation tests are highlighted., (Copyright © 2021 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.)

Background: Atypical intraepidermal melanocytic proliferations (AIMP) is a descriptive term sometimes applied to biopsies that do not fulfill diagnostic criteria of melanoma. They are common on sun-damaged skin, but their definition and management are controversial., Objective: To describe dermoscopic (DS), reflectance confocal microscopic (RCM) and histopathological features of AIMP and identify features associated with subsequent melanoma in situ (MIS)., Methods: A retrospective analysis of AIMP lesions correlated with patient outcome at two melanoma tertiary centers between 2005 and 2015., Results: Thirty-four patients were included. Nine (26%) patients had MIS in subsequent biopsies. Predictors of later MIS were target-like pattern (OR:12.0 [CI: 1.23, 117.41]; P = 0.032) and high-density vascular network (OR:12 [CI: 1.23-117.41], P: 0.032) on DS, and presence of dendritic cells touching each other (OR:9.1 [CI: 1.54, 54.59], P = 0.014) on RCM. Clinical predictors of worse outcome included a previous history of MIS at the same site. Radiotherapy for AIMP had a high failure rate (all patients presented with recurrent disease, three as AIMP and two as MIS)., Conclusions: Considering that most cases in this series received non-surgical treatment at baseline, we recommend close monitoring for lesions with target-like pattern and density vascular network on DS and treatment for lesions with progression of atypia and/or with "confluent" dendritic cells on RCM. Although the number of patients in this series is very low, early surgery is recommended for MIS cases that recur as AIMP., (© 2021 the International Society of Dermatology.)

We concurrently examine the whole genome, transcriptome, methylome, and immune cell infiltrates in baseline tumors from 77 patients with advanced cutaneous melanoma treated with anti-PD-1 with or without anti-CTLA-4. We show that high tumor mutation burden (TMB), neoantigen load, expression of IFNγ-related genes, programmed death ligand expression, low PSMB8 methylation (therefore high expression), and T cells in the tumor microenvironment are associated with response to immunotherapy. No specific mutation correlates with therapy response. A multivariable model combining the TMB and IFNγ-related gene expression robustly predicts response (89% sensitivity, 53% specificity, area under the curve [AUC], 0.84); tumors with high TMB and a high IFNγ signature show the best response to immunotherapy. This model validates in an independent cohort (80% sensitivity, 59% specificity, AUC, 0.79). Except for a JAK3 loss-of-function mutation, for patients who did not respond as predicted there is no obvious biological mechanism that clearly explained their outlier status, consistent with intratumor and intertumor heterogeneity in response to immunotherapy., Competing Interests: Declaration of interests I.P.S. has received travel support by BMS and MSD, and speaker fee by Roche, BMS, MSD, and Novartis. J.F.T. has received honoraria for advisory board participation from Merck Sharpe Dohme Australia and Bristol Myers Squibb Australia and received honoraria and travel expenses from GSK and Provectus Inc. R.A.S. has received fees for professional services from Evaxion, Provectus Biopharmaceuticals Australia, Qbiotics Group Limited, Novartis Pharma AG, MSD Sharp & Dohme (Australia), NeraCare, AMGEN Inc., Bristol-Myers Squibb, Novartis Pharmaceuticals Australia Pty Limited, Myriad Genetics GmbH, and GlaxoSmithKline Australia. G.V.L. is consultant advisor for Aduro Biotech Inc, Agenus Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Evaxion Biotech A/S, Hexel AG, Highlight Therapeutics S.L., Merck Sharpe & Dohme, Novartis Pharma AG, OncoSec, Pierre Fabre, QBiotics Group Limited, Regeneron Pharmaceuticals Inc, SkylineDX B.V., Specialised Therapeutics Australia Pty Ltd. R.P.M.S has participated in advisory boards for MSD, Novartis, and Qbiotics and received speaking honoraria from BMS. J.V.P. and N.W. are founders and shareholders of genomiQa Pty Ltd, and members of its Board. M.S.C. is a consultant advisor to MSD, BMS, Novartis, Roche, Pierre Fabre, Sanofi, Merck Serono, Nektar, Eisia, and Ideaya and received honoraria from MSD, BMS, and Novartis. A.M.M. has participated in advisory boards for BMS, MSD, Novartis, Roche, and Pierre-Fabre. C.U.B. has served on advisory boards for BMS, MSD, Roche, Novartis, GSK, AZ, Pfizer, Lilly, GenMab, Pierre Fabre, and Third Rock Ventures; received research funding from BMS, MSD, 4SC, Novartis, and NanoString; has stock ownership in Uniti Cars; and is a cofounder of Immagene BV. The remaining authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Importance: Patient-led surveillance is a promising new model of follow-up care following excision of localized melanoma., Objective: To determine whether patient-led surveillance in patients with prior localized primary cutaneous melanoma is as safe, feasible, and acceptable as clinician-led surveillance., Design, Setting, and Participants: This was a pilot for a randomized clinical trial at 2 specialist-led clinics in metropolitan Sydney, Australia, and a primary care skin cancer clinic managed by general practitioners in metropolitan Newcastle, Australia. The participants were 100 patients who had been treated for localized melanoma, owned a smartphone, had a partner to assist with skin self-examination (SSE), and had been routinely attending scheduled follow-up visits. The study was conducted from November 1, 2018, to January 17, 2020, with analysis performed from September 1, 2020, to November 15, 2020., Intervention: Participants were randomized (1:1) to 6 months of patient-led surveillance (the intervention comprised usual care plus reminders to perform SSE, patient-performed dermoscopy, teledermatologist assessment, and fast-tracked unscheduled clinic visits) or clinician-led surveillance (the control was usual care)., Main Outcomes and Measures: The primary outcome was the proportion of eligible and contacted patients who were randomized. Secondary outcomes included patient-reported outcomes (eg, SSE knowledge, attitudes, and practices, psychological outcomes, other health care use) and clinical outcomes (eg, clinic visits, skin surgeries, subsequent new primary or recurrent melanoma)., Results: Of 326 patients who were eligible and contacted, 100 (31%) patients (mean [SD] age, 58.7 [12.0] years; 53 [53%] men) were randomized to patient-led (n = 49) or clinician-led (n = 51) surveillance. Data were available on patient-reported outcomes for 66 participants and on clinical outcomes for 100 participants. Compared with clinician-led surveillance, patient-led surveillance was associated with increased SSE frequency (odds ratio [OR], 3.5; 95% CI, 0.9 to 14.0) and thoroughness (OR, 2.2; 95% CI, 0.8 to 5.7), had no detectable adverse effect on psychological outcomes (fear of cancer recurrence subscale score; mean difference, -1.3; 95% CI, -3.1 to 0.5), and increased clinic visits (risk ratio [RR], 1.5; 95% CI, 1.1 to 2.1), skin lesion excisions (RR, 1.1; 95% CI, 0.6 to 2.0), and subsequent melanoma diagnoses and subsequent melanoma diagnoses (risk difference, 10%; 95% CI, -2% to 23%). New primary melanomas and 1 local recurrence were diagnosed in 8 (16%) of the participants in the intervention group, including 5 (10%) ahead of routinely scheduled visits; and in 3 (6%) of the participants in the control group, with none (0%) ahead of routinely scheduled visits (risk difference, 10%; 95% CI, 2% to 19%)., Conclusions and Relevance: This pilot of a randomized clinical trial found that patient-led surveillance after treatment of localized melanoma appears to be safe, feasible, and acceptable. Experiences from this pilot study have prompted improvements to the trial processes for the larger trial of the same intervention., Trial Registration: http://anzctr.org.au Identifier: ACTRN12616001716459.

Non-cutaneous melanomas most frequently involve the uveal tract and mucosal membranes, including the conjunctiva. In contrast to cutaneous melanoma, they often present at an advanced clinical stage, are associated with worse clinical outcomes and show poorer responses to immunotherapy. The mutational load within most non-cutaneous melanomas reflects their lower ultraviolet light (UV) exposure. The genetic drivers within non-cutaneous melanomas are heterogeneous. Within ocular melanomas, posterior uveal tract melanomas typically harbour one of two distinct, sets of driver mutations and alterations of clinical and biological significance. In contrast to posterior uveal tract melanomas, anterior uveal tract melanomas of the iris and conjunctival melanomas frequently carry both a higher mutational burden and specific mutations linked with UV exposure. The genetic drivers in iris melanomas more closely resemble those of the posterior uveal tract, whereas conjunctival melanomas harbour similar genetic driver mutations to cutaneous melanomas. Mucosal melanomas occur in sun-shielded sites including sinonasal and oral cavities, nasopharynx, oesophagus, genitalia, anus and rectum, and their mutational landscape is frequently associated with a dominant process of spontaneous deamination and infrequent presence of UV mutation signatures. Genetic drivers of mucosal melanomas are diverse and vary with anatomic location. Further understanding of the causes of already identified recurrent molecular events in non-cutaneous melanomas, identification of additional drivers in specific subtypes, integrative multi-omics analyses and analysis of the tumor immune microenvironment will expand knowledge in this field. Furthermore, such data will likely uncover new therapeutic strategies which will lead to improved clinical outcomes in non-cutaneous melanoma patients., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Atypical Spitzoid melanocytic tumors are diagnostically challenging. Many studies have suggested various genomic markers to improve classification and prognostication. We aimed to assess whether next-generation sequencing studies using the Tempus xO assay assessing mutations in 1711 cancer-related genes and performing whole transcriptome mRNA sequencing for structural alterations could improve diagnostic agreement and accuracy in assessing neoplasms with Spitzoid histologic features. Twenty expert pathologists were asked to review 70 consultation level cases with Spitzoid features, once with limited clinical information and again with additional genomic information. There was an improvement in overall agreement with additional genomic information. Most significantly, there was increase in agreement of the diagnosis of conventional melanoma from moderate (κ=0.470, SE=0.0105) to substantial (κ=0.645, SE=0.0143) as measured by an average Cohen κ. Clinical follow-up was available in all 70 cases which substantiated that the improved agreement was clinically significant. Among 3 patients with distant metastatic disease, there was a highly significant increase in diagnostic recognition of the cases as conventional melanoma with genomics (P<0.005). In one case, none of 20 pathologists recognized a tumor with BRAF and TERT promoter mutations associated with fatal outcome as a conventional melanoma when only limited clinical information was provided, whereas 60% of pathologists correctly diagnosed this case when genomic information was also available. There was also a significant improvement in agreement of which lesions should be classified in the Spitz category/WHO Pathway from an average Cohen κ of 0.360 (SE=0.00921) to 0.607 (SE=0.0232) with genomics., Competing Interests: Conflicts of Interest and Source of Funding: This study was supported by the IDP Foundation Inc. R.A.S. is supported by a National Health and Medical Research Council of Australia (NHMRC) Program Grant and Practitioner Fellowship. P.G. has received royalties from Elsevier for textbooks and has served as a consultant for Castle Biosciences and DermTech Inc. K.B. has received royalties from Elsevier for textbooks. R.A.S. has received fees for professional services from Qbiotics, Novartis, Merck Sharp & Dohme, NeraCare, AMGEN Inc., Bristol-Myers Squibb, Myriad Genetics, and GlaxoSmithKline. C.R.S. has received fees for professional services from Myriad Genetics, Novartis, Orlucent, and SkinCure Oncology. M.T.T. has served as a consultant and advisor for Myriad Genetics, Merck Sharp & Dohme, Nanostring LLC, and Novartis. For the remaining authors none were declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Melanoma can present with osteocartilaginous differentiation, however few reports exist on this rare subtype. We present eight cases of melanoma with osteocartilaginous differentiation to highlight its clinical, pathological and molecular features. The cases showed no association with gender (5 males and 3 females) or age (range 23-84 years). Cases included both primary melanomas and distant metastases (6 and 2, respectively), with the majority arising from cutaneous sites (7/8) and the remaining case from a mucosal site. Tumour-infiltrating lymphocyte (TIL) score ranged from 0 to 3 (median 1), and 2/8 lesions had evidence of inflammatory changes or antecedent trauma. No recurrent mutations were found in the tumours by next generation sequencing, and the mutations observed were typical of melanoma rather than osteosarcomatous lesions. The majority of tumours stained positive for melanoma markers including S100, HMB45, Melan-A, SOX10 and MITF. Staining of the osteoblastic marker SATB2 varied from negative to widespread positive. We demonstrate that melanomas with osteocartilaginous differentiation are heterogeneous in presentation and are not typified by a recurrent mutation in cancer associated genes. Where uncertainty exists in diagnosing an osteocartilaginous lesion, a diagnosis of melanoma can be supported by the presence of genomic mutations typical of melanoma such as BRAF, NRAS and NF1, and IHC staining positive for S100, HMB45, Melan-A, SOX10 and MITF. SATB2 may be positive in these lesions and thus should not be used to rule out melanoma., (Copyright © 2021 Royal College of Pathologists of Australasia. All rights reserved.)

Importance: Early melanoma diagnosis is associated with better health outcomes, but there is insufficient evidence that screening, such as having routine skin checks, reduces mortality., Objective: To assess melanoma-specific and all-cause mortality associated with melanomas detected through routine skin checks, incidentally or patient detected. A secondary aim was to examine patient, sociodemographic, and clinicopathologic factors associated with different modes of melanoma detection., Design, Setting, and Participants: This prospective, population-based, cohort study included patients in New South Wales, Australia, who were diagnosed with melanoma over 1 year from October 23, 2006, to October 22, 2007, in the Melanoma Patterns of Care Study and followed up until 2018 (mean [SD] length of follow-up, 11.9 [0.3] years) by using linked mortality and cancer registry data. All patients who had invasive melanomas recorded at the cancer registry were eligible for the study, but the number of in situ melanomas was capped. The treating doctors recorded details of melanoma detection and patient and clinical characteristics in a baseline questionnaire. Histopathologic variables were obtained from pathology reports. Of 3932 recorded melanomas, data were available and analyzed for 2452 (62%; 1 per patient) with primary in situ (n = 291) or invasive (n = 2161) cutaneous melanoma. Data were analyzed from March 2020 to January 2021., Main Outcomes and Measures: Melanoma-specific mortality and all-cause mortality., Results: A total of 2452 patients were included in the analyses. The median age at diagnosis was 65 years (range, 16-98 years), and 1502 patients (61%) were men. A total of 858 patients (35%) had their melanoma detected during a routine skin check, 1148 (47%) self-detected their melanoma, 293 (12%) had their melanoma discovered incidentally when checking another skin lesion, and 153 (6%) reported "other" presentation. Routine skin-check detection of invasive melanomas was associated with 59% lower melanoma-specific mortality (subhazard ratio, 0.41; 95% CI, 0.28-0.60; P < .001) and 36% lower all-cause mortality (hazard ratio, 0.64; 95% CI, 0.54-0.76; P < .001), adjusted for age and sex, compared with patient-detected melanomas. After adjusting for prognostic factors including ulceration and mitotic rate, the associations were 0.68 (95% CI, 0.44-1.03; P = .13), and 0.75 (95% CI, 0.63-0.90; P = .006), respectively. Factors associated with higher odds of routine skin-check melanoma detection included being male (female vs male, odds ratio [OR], 0.73; 95% CI, 0.60-0.89; P = .003), having previous melanoma (vs none, OR, 2.36; 95% CI, 1.77-3.15; P < .001), having many moles (vs not, OR, 1.39; 95% CI, 1.10-1.77; P = .02), being 50 years or older (eg, 50-59 years vs <40 years, OR, 2.89; 95% CI, 1.92-4.34; P < .001), and living in nonremote areas (eg, remote or very remote vs major cities, OR, 0.23; 95% CI, 0.05-1.04; P = .003)., Conclusions and Relevance: In this cohort study, melanomas diagnosed through routine skin checks were associated with significantly lower all-cause mortality, but not melanoma-specific mortality, after adjustment for patient, sociodemographic, and clinicopathologic factors.

Regression in melanoma is an immunological phenomenon that results in partial or complete replacement of the tumor with variably vascular fibrous tissue, often accompanied by pigment-laden macrophages and chronic inflammation. In some cases, tumor-infiltrating lymphocytes (TILs) may represent the earliest phase of this process. The prognostic significance of regression has long been a matter of debate, with inconsistent findings reported in the literature to date. This study sought to determine whether regression in primary cutaneous melanomas predicted sentinel lymph node (SLN) status and survival outcomes in a large cohort of patients managed at a single centre. Clinical and pathological parameters for 8,693 consecutive cases were retrieved. Associations between regression and SLN status, overall survival (OS), melanoma-specific survival (MSS) and recurrence-free survival (RFS) were investigated using logistic and Cox regression. Histological evidence of regression was present in 1958 cases (22.5%). Regression was significantly associated with lower Breslow thickness, lower mitotic rate, and absence of ulceration (p < 0.0001). Multivariable analysis showed that regression in combination with TILs independently predicted a negative SLN biopsy (OR 0.33; 95% C.I. 0.20-0.52; p < 0.0001). Patients whose tumors showed both regression and TILs had the highest 10-year OS (65%, 95% C.I. 59-71%), MSS (85%, 95% C.I. 81-89%), and RFS (60%, 95% C.I. 54-66%). On multivariable analyses, the concurrent presence of regression and TILs independently predicted the lowest risk of death from melanoma (HR 0.69; 95% C.I. 0.51-0.94; p = 0.0003) as well as the lowest rate of disease recurrence (HR 0.71; 95% C.I. 0.58-0.85; p < 0.0001). However, in contrast, in the subgroup analysis of Stage III patients, the presence of regression predicted the lowest OS and RFS, with MSS showing a similar trend. Overall, these findings indicate a prognostically favorable role of regression in primary cutaneous melanoma. However, in Stage III melanoma patients, regression may be a marker of more aggressive disease., (© 2021. Crown.)

Lentigo maligna (LM) is a common in situ melanoma subtype arising on chronically sun-damaged skin and mostly affects the head and neck region. Localisation in cosmetically sensitive areas, difficulty to obtain wide resection margins and advanced patient age/comorbidities have encouraged investigation of less invasive therapeutic strategies than surgery in managing complex cases of LM. Radiotherapy and imiquimod have emerged as alternative treatment options in this context. The treatment of LM with imiquimod cream can be challenging due to the nature of the disease including its often large size, variegated appearance, involvement of adnexal structures, poorly defined peripheral edge and frequent localisation close to sensitive structures such as the eyes and lips, and elderly patients with multiple comorbidities. Prolonged and unpredictable inflammatory reaction and side effects and compliance with a patient-delivered therapy can also be challenging. In the literature to date, studies evaluating the use of imiquimod to treat LM have utilised varying methodologies and provided short follow-up and these limitations have impaired the development of clear guidelines for dosage and management of side effects. Based on our multidisciplinary experience and review of the literature, we propose practical clinical strategies for the use of imiquimod for treating LM, detailing optimal administration procedures in various clinical scenarios and long-term management, with the aim of facilitating optimal patient outcomes., (© 2021 The Australasian College of Dermatologists.)

Recent advances in single-cell transcriptomics have greatly improved knowledge of complex transcriptional programs, rapidly expanding our knowledge of cellular phenotypes and functions within the tumour microenvironment and immune system. Several new single-cell technologies have been developed over recent years that have enabled expanded understanding of the mechanistic cells and biological pathways targeted by immunotherapies such as immune checkpoint inhibitors, which are now routinely used in patient management with high-risk early-stage or advanced melanoma. These technologies have method-specific strengths, weaknesses and capabilities which need to be considered when utilising them to answer translational research questions. Here, we provide guidance for the implementation of single-cell transcriptomic analysis platforms by reviewing the currently available experimental and analysis workflows. We then highlight the use of these technologies to dissect the tumour microenvironment in the context of cancer patients treated with immunotherapy. The strategic use of single-cell analytics in clinical settings are discussed and potential future opportunities are explored with a focus on their use to rationalise the design of novel immunotherapeutic drug therapies that will ultimately lead to improved cancer patient outcomes.

Neoantigens are now recognized drivers of the antitumor immune response. Recurrent neoantigens, shared among groups of patients, have thus become increasingly coveted therapeutic targets. Here, we report on the data-driven identification of a robustly presented, immunogenic neoantigen that is derived from the combination of HLA-A*01:01 and RAS.Q61K. Analysis of large patient cohorts indicated that this combination applies to 3% of patients with melanoma. Using HLA peptidomics, we were able to demonstrate robust endogenous presentation of the neoantigen in 10 tumor samples. We detected specific reactivity to the mutated peptide within tumor-infiltrating lymphocytes (TILs) from 2 unrelated patients, thus confirming its natural immunogenicity. We further investigated the neoantigen-specific clones and their T cell receptors (TCRs) via a combination of TCR sequencing, TCR overexpression, functional assays, and single-cell transcriptomics. Our analysis revealed a diverse repertoire of neoantigen-specific clones with both intra- and interpatient TCR similarities. Moreover, 1 dominant clone proved to cross-react with the highly prevalent RAS.Q61R variant. Transcriptome analysis revealed a high association of TCR clones with specific T cell phenotypes in response to cognate melanoma, with neoantigen-specific cells showing an activated and dysfunctional phenotype. Identification of recurrent neoantigens and their reactive TCRs can promote "off-the-shelf" precision immunotherapies, alleviating limitations of personalized treatments.

Background: Metastasectomy for selected patients with melanoma was associated with improved survival in the era before effective systemic therapy. Emerging evidence shows that these benefits persist even in this era of BRAF-targeted therapy and immune checkpoint inhibitor immunotherapy. This study aimed to evaluate the outcomes of salvage metastasectomy after failure of systemic therapy., Methods: Stage 3 or 4 melanoma patients with extracranial disease progression after at least 4 weeks of systemic treatment between 2009 and 2020 were identified and categorized as resected to no evidence of disease (NED), non-progressive residual disease (NPRD), or progressive residual disease (PRD). Systemic therapy was stratified into BRAF-targeted therapy, immune checkpoint inhibitor immunotherapy, or both. The end points of overall survival (OS), progression-free survival (PFS), and locoregional disease control (LRC) were assessed using Kaplan-Meier curves. Uni- and multivariable Cox regression procedures were used to examine factors associated with OS, PFS and LRC., Results: The study enrolled 190 patients. Among all the patients, the 5-year OS from metastatectomy was 52%, the 3-year PFS was 21%, and the 5-year LRC was 61%. After resection to NED, NPRD, and PRD, the 5-year OS values were 69%, 62% and 8%, respectively. Fewer lines of preoperative therapy, use of preoperative immunotherapy, and resection to NED were predictors of improved OS. After resection to NED, NPRD, and PRD, the 3-year PFS values were 23%, 24% and 10%, and the 5-year LRC values were 61%, 72% and 34%, respectively., Conclusions: Salvage metastasectomy was associated with durable survival and disease control, particularly after resection to NED, preoperative immunotherapy, and fewer lines of preoperative systemic therapy., (© 2021. Society of Surgical Oncology.)

Among the histogenic subtypes of melanoma, nodular melanoma (NM) is the major contributor for thicker and fatal melanomas and it has been associated with melanoma-specific death in thin tumours, highlighting an important subgroup of 'aggressive thin' melanomas. This review provides a synthesis of the distinct characteristics of NM, with respect to epidemiology and risk factors, clinical presentation, histopathology, molecular and dermoscopic aspects, and screening practices. The real challenges are to find better biomarkers of aggressiveness and to know whether the control of such aggressive melanomas can be influenced by targeted interventions such as early detection, drug interventions and preventive strategies., (© 2021 British Association of Dermatologists.)

Cutaneous melanoma (CM) is the most aggressive form of skin cancer, and its worldwide incidence is rapidly increasing. Early stages can be successfully treated by surgery, but once metastasis has occurred, the prognosis is poor. However, some 5-10% of thick (≥2 mm) melanomas do not follow this scenario and run an unpredictable course. Little is known about the factors that contribute to metastasis in some patient with thick melanomas and the lack thereof in thick melanoma patients who never develop metastatic disease. We were therefore interested to study differential gene expression and pathway analysis and compare non-metastatic and metastatic thick melanomas. We found that the TNF-like weak inducer of apoptosis (TWEAK) pathway was upregulated in thick non-metastasizing melanomas. MAP3K14 (NIK1), BIRC2 (cIAP1), RIPK1, CASP7, CASP8, and TNF play an important role in inhibiting proliferation and invasion of tumor cells via the activation of the non-canonical NF-κB signaling pathway. In particular, this pathway sensitizes melanoma cells to TNF-alpha and activates the apoptosis module of the TWEAK pathway in thick non-metastasizing melanomas. Hence, our study suggests a potential role of the TWEAK pathway in inhibiting thick melanoma from metastasis. Exploitation of these genes and the pathway they control may open future therapeutic avenues.

Background: Lentigo maligna (LM) is a subtype of melanoma in situ with poorly defined margins and a high recurrence rate. The biological behaviour of LM appears to differ widely between cases, from biologically indolent to biologically active variants, with some patients experiencing multiple recurrences. It is not known whether this is secondary to inadequate margins, field cancerization or the innate biology of the lesion itself., Objectives: (a) Describe the margins of LM in detail by analysing LM in three zones, that is centre, edge and surround using reflectance confocal microscopy (RCM) and histopathology; (b) ascertain association of histological distance of LM and atypical melanocytic hyperplasia from the surgical margin with multi-recurrent (MR) disease and (c) identify features (clinical, dermoscopy, RCM and histopathology) associated with MR LM., Methods: (1) Descriptive observational study comparing the centre, edge and surround of LM on histopathology and RCM; (2) retrospective cohort study comparing parameters associated with MR and non-recurrent (NR) LM., Results: 30 patients (median follow-up time 6.2 years) were included. On histopathology, confluent or near confluent lentiginous proliferation, melanocyte density >15 per 0.5 mm and adnexal spread were best for distinguishing surround from edge of LM. On RCM, predominant melanocytes, lentiginous proliferation and pleomorphism distinguished surround from centre/edge. MR patients had a median histological distance of LM from the surgical margin of 2mm (versus NR patients with an average distance of 4mm). MR patients had a greater proportion of more florid features, compared with NR on histopathology at both the centre and the edge but were similar in the surround., Conclusion: These data may help pathologists and confocalists better define margins of LM. More florid features in MR patients, despite a similar background of sun-damaged skin, suggest the innate biology of the lesion rather than the field of cancerization may explain MR LM., (© 2021 European Academy of Dermatology and Venereology.)

Mitoses are often assessed by pathologists to assist the diagnosis of cancer, and to grade malignancy, informing prognosis. Historically, this has been done by expressing the number of mitoses per n high power fields (HPFs), ignoring the fact that microscope fields may differ substantially, even at the same high power (×400) magnification. Despite a requirement to define HPF size in scientific papers, many authors fail to address this issue adequately. The problem is compounded by the switch to digital pathology systems, where ×400 equivalent fields are rectangular and also vary in the area displayed. The potential for error is considerable, and at times this may affect patient care. This is easily solved by the use of standardized international (SI) units. We, therefore, recommend that features such as mitoses are always counted per mm 2 , with an indication of the area to be counted and the method used (usually "hotspot" or "average") to obtain the results., (© 2021. World Health Organization.)

Context: Thyroid dysfunction occurs commonly following immune checkpoint inhibition. The etiology of thyroid immune-related adverse events (irAEs) remains unclear and clinical presentation can be variable., Objective: This study sought to define thyroid irAEs following immune checkpoint inhibitor (ICI) treatment and describe their clinical and biochemical associations., Methods: We performed a retrospective cohort study of thyroid dysfunction in patients with melanoma undergoing cytotoxic T-lymphocyte antigen-4 (CTLA-4) and/or programmed cell death protein-1 (PD-1) based ICI treatment from November 1, 2009, to December 31, 2019. Thyroid function was measured at baseline and at regular intervals following the start of ICI treatment. Clinical and biochemical features were evaluated for associations with ICI-associated thyroid irAEs. The prevalence of thyroid autoantibodies and the effect of thyroid irAEs on survival were analyzed., Results: A total of 1246 patients were included with a median follow-up of 11.3 months. Five hundred and eighteen (42%) patients developed an ICI-associated thyroid irAE. Subclinical thyrotoxicosis (n = 234) was the most common thyroid irAE, followed by overt thyrotoxicosis (n = 154), subclinical hypothyroidism (n = 61), and overt hypothyroidism (n = 39). Onset of overt thyrotoxicosis occurred a median of 5 weeks (interquartile range [IQR] 2-8) after receipt of a first dose of ICI. Combination immunotherapy was strongly associated with development of overt thyrotoxicosis (odds ratio [OR] 10.8, 95% CI 4.51-25.6 vs CTLA-4 monotherapy; P < .001), as was female sex (OR 2.02, 95% CI 1.37-2.95; P < .001) and younger age (OR 0.83 per 10 years, 95% CI 0.72-0.95; P = .007). By comparison, median onset of overt hypothyroidism was 14 weeks (IQR 8-25). The frequency of overt hypothyroidism did not differ between different ICI types. The strongest associations for hypothyroidism were higher baseline thyroid-stimulating hormone (OR 2.33 per mIU/L, 95% CI 1.61-3.33; P < .001) and female sex (OR 3.31, 95% CI 1.67-6.56; P = .01). Overt thyrotoxicosis was associated with longer progression free survival (hazard ratio [HR] 0.68, 95% CI 0.49-0.94; P = .02) and overall survival (HR 0.57, 95% CI 0.39-0.84; P = .005). There was no association between hypothyroidism and cancer outcomes., Conclusion: Thyroid irAEs are common and there are multiple distinct phenotypes. Different thyroid irAE subtypes have unique clinical and biochemical associations, suggesting potentially distinct etiologies for thyrotoxicosis and hypothyroidism arising in this context., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Although previously the mainstay of treatment, the role of surgery in the management of patients with oligometastatic stage IV melanoma has changed with the advent of effective systemic therapies (most notably immunotherapy). Contemporary treatment options for patients with asymptomatic solitary or oligo-metastases include upfront surgery followed by adjuvant immunotherapy or upfront immunotherapy with salvage surgery as required. For suspected solitary or oligo-metastases, surgery serves both diagnostic and therapeutic purposes. Advances in radiological technology allow metastases to be detected earlier and surgery to be less morbid. Surgical morbidities are generally more tolerable than serious immune-related adverse effects, but surgery may be less effective. Upfront immunotherapy ensures that futile surgery is not offered for rapidly progressive disease. It also provides an opportunity to assess response to treatment, which predicts outcome, and may obviate the need for surgery. However, it is important not to miss a window of opportunity for surgical intervention, whereby if disease progresses on immunotherapy it becomes unresectable. In situations where local therapy is recommended but surgery is not desired, stereotactic radiosurgery may be an effective alternative. The decision-making process regarding upfront surgery versus immunotherapy needs to take place within a specialist melanoma multidisciplinary setting and be customised to individual patient and tumour factors. Ultimately, high-level clinical trial evidence is required to resolve uncertainties in the management of patients with oligometastatic stage IV melanoma but the complexity of the varying presentations may make trial design challenging., Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: MSC has served on advisory boards for Bristol Myers Squibb, MSD, Amgen, Novartis, Pierre Fabre, Roche, Sanofi, Merck, Ideaya, Regeneron, Nektar, Eisai, Oncosec and Qbiotics and has received honoraria from Bristol Myers Squibb, MSD and Novartis. IPS has received travel support from BMS and MSD, and speaker honoraria from Roche, BMS and MSD. AJS has received honoraria for advisory board participation from Qbiotis and speaker honoraria from Stryker. RAS has received fees for professional services from Qbiotics, Merck Sharp & Dohme, GlaxoSmithKline, Bristol-Myers Squibb, Dermpedia, Novartis, Myriad, NeraCare and Amgen. GVL is a consultant advisor for Aduro Biotech Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Highlight Therapeutics S.L., Merck Sharpe & Dohme, Novartis Pharma AG, Nektar, Pierre Fabre, QBiotics Group Limited, Regeneron Pharmaceuticals Inc. AH has received honoraria for advisory board participation from Qbiotis, Bayer and Amgen. RPMS has received honoraria for advisory board participation from MSD, Novartis and Qbiotics and speaking honoraria from BMS. JFT has received honoraria for advisory board participation from BMS Australia, MSD Australia, GSK and Provectus Inc, and travel support from GSK and Provectus Inc. AMM has received honoraria for advisory board participation from BMS, MSD, Novartis, Roche, Pierre-Fabre, QBiotics. All other authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2021. Published by Elsevier Ltd. All rights reserved.)

Background: A nomogram to predict sentinel node (SN) positivity [the Melanoma Institute Australia (MIA) nomogram] was recently developed and externally validated using two large single-institution databases. However, there remains a need to further validate the nomogram's performance using population-based data., Objectives: To perform further validation of the nomogram using a European national patient cohort., Methods: Patients with cutaneous melanoma who underwent SN biopsy in the Netherlands between 2000 and 2014 were included. Their data were obtained from the Dutch Pathology Registry. The predictive performance of the nomogram was assessed by discrimination (C-statistic) and calibration. Negative predictive values (NPVs) were calculated at various predicted probability cutoffs., Results: Of the 3049 patients who met the eligibility criteria, 23% (691) were SN positive. Validation of the MIA nomogram (including the parameters Breslow thickness, ulceration, age, melanoma subtype and lymphovascular invasion) showed a good C-statistic of 0·69 (95% confidence interval 0·66-0·71) with excellent calibration (R 2 = 0·985, P = 0·40). The NPV of 90·1%, found at a 10% predicted probability cutoff for having a positive SN biopsy, implied that by using the nomogram, a 16·3% reduction in the rate of performing an SN biopsy could be achieved with an error rate of 1·6%. Validation of the MIA nomogram considering mitotic rate as present or absent showed a C-statistic of 0·70 (95% confidence interval 0·68-0·74)., Conclusions: This population-based validation study in European patients with melanoma confirmed the value of the MIA nomogram in predicting SN positivity. Its use will spare low-risk patients the inconvenience, cost and potential risks of SN biopsy while ensuring that high-risk patients are still identified., (© 2021 British Association of Dermatologists.)

Neoadjuvant immunotherapy is gathering pace, particularly in melanoma. A recent study of pembrolizumab and HDI not only further supports the safety and activity of neoadjuvant anti-PD-1 based immunotherapy but also highlights neoadjuvant therapy as a solid platform for drug development that is likely to become a standard-of-care in the near future. See related article by Najjar et al., p. 4195 ., (©2021 American Association for Cancer Research.)

Most international clinical guidelines recommend 5-10 mm clinical margins for excision of melanoma in situ (MIS). While the evidence supporting this is weak, these guidelines are generally consistent. However, as a result of the high incidence of subclinical extension of MIS, especially of the lentigo maligna (LM) subtype, wider margins will often be needed to achieve complete histologic clearance. In this review, we assessed all available contemporary evidence on clearance margins for MIS. No randomized trials were identified and the 31 non-randomized studies were largely retrospective reviews of single-surgeon or single-institution experiences using Mohs micrographic surgery (MMS) for LM or staged excision (SE) for treatment of MIS on the head/neck and/or LM specifically. The available data challenge the adequacy of current international guidelines as they consistently demonstrate the need for clinical margins > 5 mm and often > 10 mm. For LM, any MIS on the head/neck, and/or ≥ 3 cm in diameter, all may require wider clinical margins because of the higher likelihood of subclinical spread. Histologic clearance should be confirmed prior to undertaking complex reconstruction. However, it is not clear whether wider margins are necessary for all MIS subtypes. Indeed, it seems that this is unlikely to be the case. Until optimal surgical margins can be better defined in a randomized trial setting, ideally controlling for MIS subtype and including correlation with histologic excision margins, techniques such as preliminary border mapping of large, ill-defined lesions and, most importantly, sound clinical judgement will be needed when planning surgical clearance margins for the treatment of MIS., (© 2021. The Author(s).)

How targeted therapies and immunotherapies shape tumors, and thereby influence subsequent therapeutic responses, is poorly understood. In the present study, we show, in melanoma patients and mouse models, that when tumors relapse after targeted therapy with MAPK pathway inhibitors, they are cross-resistant to immunotherapies, despite the different modes of action of these therapies. We find that cross-resistance is mediated by a cancer cell-instructed, immunosuppressive tumor microenvironment that lacks functional CD103 + dendritic cells, precluding an effective T cell response. Restoring the numbers and functionality of CD103 + dendritic cells can re-sensitize cross-resistant tumors to immunotherapy. Cross-resistance does not arise from selective pressure of an immune response during evolution of resistance, but from the MAPK pathway, which not only is reactivated, but also exhibits an increased transcriptional output that drives immune evasion. Our work provides mechanistic evidence for cross-resistance between two unrelated therapies, and a scientific rationale for treating patients with immunotherapy before they acquire resistance to targeted therapy., (© 2021. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Background: Whether melanoma in histological contiguity with a naevus [naevus-associated melanoma (NAM)] is distinctly different from melanoma arising de novo remains unclear., Objectives: To determine whether the characteristics of de novo melanoma differ from NAM and are not due to naevus obliteration in thicker tumours., Methods: We conducted a multicentre retrospective study of de novo melanoma and NAM in seven referral centres in Europe, Australia and the USA between 2006 and 2015., Results: In a total of 9474 localized melanomas, de novo melanoma was associated with thicker tumours and body site differences compared with NAM. In the subset of T 1 melanomas (n = 5307), similar body site differences were found in multivariate analysis by body site. When compared with NAM, de novo melanoma was more likely to affect older individuals (≥ 70 years) when located on the head/neck [odds ratio (OR) 4·65, 95% confidence interval (CI) 2·55-8·46], the trunk (OR 1·82, 95% CI 1·40-2·36) or the upper extremity (OR 1·69, 95% CI 1·14-2·50), was more likely to affect female patients when located on the lower extremities (OR 1·36, 95% CI 1·03-1·80), and was more likely to be of the nodular melanoma subtype (OR 2·23, 95% CI 1·14-4·35) when located on the trunk. De novo melanoma was less likely to have regression present compared with NAM., Conclusions: Clinicopathological and body site differences between de novo melanoma and NAM support the divergent pathway model of development. These differences were also found in thin melanomas, suggesting that de novo melanomas are different from NAM and their differences are not due to the obliteration of naevus remnants in thicker tumours., (© 2021 British Association of Dermatologists.)

Background: Pathologists sometimes disagree over the histopathologic diagnosis of melanoma. 'Over-calling' and 'under-calling' of melanoma may harm individuals and healthcare systems., Objectives: To estimate the extent of 'over-calling' and 'under-calling' of melanoma for a population undergoing one excision per person and to model the impact of potential solutions., Methods: In this epidemiological modelling study, we undertook simulations using published data on the prevalence and diagnostic accuracy of melanocytic histopathology in the U.S., Population: We simulated results for 10 000 patients each undergoing excision of one melanocytic lesion, interpreted by one community pathologist. We repeated the simulation using a hypothetical intervention that improves diagnostic agreement between community pathologist and a specialist dermatopathologist. We then evaluated four scenarios for how melanocytic lesions judged to be neither clearly benign (post-test probability of melanoma < 5%), nor clearly malignant (post-test probability of melanoma > 90%) might be handled, before sending for expert dermatopathologist review to decide the final diagnosis. These were (1) no intervention before expert review, (2) formal second community pathologist review, (3) intervention to increase diagnostic agreement and (4) both the intervention and formal second community pathologist review. The main outcomes were the probability of 'over-calling' and 'under-calling' melanoma, and number of lesions requiring expert referral for each scenario., Results: For 10 000 individuals undergoing excision of one melanocytic lesion, interpreted by a community pathologist, a hypothetical intervention to improve histopathology agreement reduced the number of benign lesions 'over-called' as melanoma from 308 to 164 and the number of melanomas 'under-called' from 289 to 240. If all uncertain diagnoses were sent for expert review, the number of referrals would decrease from 1500 to 737 cases if formal second community pathologist review was used, and to 701 cases if the hypothetical intervention was additionally used., Conclusions: Interventions to improve histopathology agreement may reduce melanoma 'over-calling' and 'under-calling'., (© 2021 European Academy of Dermatology and Venereology.)

While immune checkpoint inhibitors targeting the CTLA-4 and PD-1 receptors have significantly improved outcomes of many patients with metastatic melanoma, there remains a group of patients who demonstrate no benefit. In this study, we sought to characterise patients who do not respond to anti-PD-1-based therapies based on their clinical, genetic and immune profiles. Forty patients with metastatic melanoma who did not respond to anti-PD-1 +/- anti-CTLA-4 treatment were identified. Targeted RNA sequencing ( n = 37) was performed on pretreatment formalin-fixed paraffin-embedded (FFPE) melanoma specimens. Patients clustered into two groups based on the expression profiles of 26 differentially expressed genes: an immune gene rich group ( n = 17) expressing genes associated with immune and T cell signalling, and a second group ( n = 20) expressing genes associated with metabolism, signal transduction and neuronal signalling. Multiplex immunohistochemistry validated significantly higher densities of tumour-infiltrating lymphocytes (TILs) and macrophages in the immune gene-rich group. This TIL-high subset of patients also demonstrated higher expression of alternative immune-regulatory drug targets compared to the TIL-low group. Patients were also subdivided into rapid progressors and other progressors (cut-off 2 mo progression-free survival), with significantly lower TILs ( p = 0.04) and CD68+ macrophages ( p = 0.0091) in the rapid progressors. Furthermore, a trend towards a higher tumour burden was observed in rapid progressors ( p = 0.06). These data highlight the need for a personalised and multilayer (clinical and molecular) approach for identifying the most appropriate treatments for anti-PD-1 resistant patients and provides insight into how individual treatment strategies can be achieved.

Cutaneous melanoma remains the most lethal skin cancer, and ranks third among all malignancies in terms of years of life lost. Despite the advent of immune checkpoint and targeted therapies, only roughly half of patients with advanced melanoma achieve a durable remission. Sirtuin 5 (SIRT5) is a member of the sirtuin family of protein deacylases that regulates metabolism and other biological processes. Germline Sirt5 deficiency is associated with mild phenotypes in mice. Here we showed that SIRT5 was required for proliferation and survival across all cutaneous melanoma genotypes tested, as well as uveal melanoma, a genetically distinct melanoma subtype that arises in the eye and is incurable once metastatic. Likewise, SIRT5 was required for efficient tumor formation by melanoma xenografts and in an autochthonous mouse Braf Pten-driven melanoma model. Via metabolite and transcriptomic analyses, we found that SIRT5 was required to maintain histone acetylation and methylation levels in melanoma cells, thereby promoting proper gene expression. SIRT5-dependent genes notably included MITF, a key lineage-specific survival oncogene in melanoma, and the c-MYC proto-oncogene. SIRT5 may represent a druggable genotype-independent addiction in melanoma.

A significant number of patients (pts) with metastatic melanoma do not respond to anti-programmed cell death 1 (PD1) therapies. Identifying predictive biomarkers therefore remains an urgent need. We retrospectively analyzed plasma DNA of pts with advanced melanoma treated with PD-1 antibodies, nivolumab or pembrolizumab, for five PD-1 genotype single nucleotide polymorphisms (SNPs): PD1.1 (rs36084323, G>A), PD1.3 (rs11568821, G>A), PD1.5 (rs2227981, C>T) PD1.6 (rs10204225, G>A) and PD1.9 (rs2227982, C>T). Clinico-pathological and treatment parameters were collected, and presence of SNPs correlated with response, progression free survival (PFS) and overall survival (OS). 115 patients were identified with a median follow up of 18.7 months (range 0.26 - 52.0 months). All were Caucasian; 27% BRAF V600 mutation positive. At PD-1 antibody commencement, 36% were treatment-naïve and 52% had prior ipilimumab. The overall response rate was 43%, 19% achieving a complete response. Overall median PFS was 11.0 months (95% CI 5.4 - 17.3) and median OS was 31.1 months (95% CI 23.2 - NA). Patients with the G/G genotype had more complete responses than with A/G genotype (16.5% vs. 2.6% respectively) and the G allele of PD1.3 rs11568821 was significantly associated with a longer median PFS than the AG allele, 14.1 vs. 7.0 months compared to the A allele (p=0.04; 95% CI 0.14 - 0.94). No significant association between the remaining SNPs and responses, PFS or OS were observed. Despite limitations in sample size, this is the first study to demonstrate an association of a germline PD-1 polymorphism and PFS in response to anti-PD-1 therapy in pts with metastatic melanoma. Extrinsic factors like host germline polymorphisms should be considered with tumor intrinsic factors as predictive biomarkers for immune checkpoint regulators., Competing Interests: MC has a consultant advisory role with BMS, MSD, Amgen, Novartis, Pierre Fabre, Roche, Sanofi, Merck and Co, Ideaya, Regeneron, Nektar, Eisai and Q biotics and OncoSec. AMM is a consultant advisor to BMS, MSD, Novartis, Roche, Pierre-Fabre, QBiotics. RAS has received fees for professional services from Qbiotics, Novartis, Merck Sharp & Dohme, NeraCare, AMGEN Inc., Bristol-Myers Squibb, Myriad Genetics, and GlaxoSmithKline. JC has sat on advisory boards for Novartis and GSK. GL is consultant advisor for Aduro Biotech Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Hexel AG, Highlight Therapeutics S.L., Merck Sharpe & Dohme, Novartis Pharma AG, OncoSec, Pierre Fabre, QBiotics Group Limited, Regeneron Pharmaceuticals Inc, SkylineDX B.V., and Specialised Therapeutics Australia Pty Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Parakh, Musafer, Paessler, Witkowski, Suen, Tutuka, Carlino, Menzies, Scolyer, Cebon, Dobrovic, Long, Klein and Behren.)

Background: Guidelines for pathological evaluation of neoadjuvant specimens and pathological response categories have been developed by the International Neoadjuvant Melanoma Consortium (INMC). As part of the Optimal Neo-adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) clinical trial of neoadjuvant combination anti-programmed cell death protein 1/anti-cytotoxic T-lymphocyte-associated protein 4 immunotherapy for stage III melanoma, we sought to determine interobserver reproducibility of INMC histopathological assessment principles, identify specific tumour bed histopathological features of immunotherapeutic response that correlated with recurrence and relapse-free survival (RFS) and evaluate proposed INMC pathological response categories for predicting recurrence and RFS., Patients and Methods: Clinicopathological characteristics of lymph node dissection specimens of 83 patients enrolled in the OpACIN-neo clinical trial were evaluated. Two methods of assessing histological features of immunotherapeutic response were evaluated: the previously described immune-related pathologic response (irPR) score and our novel immunotherapeutic response score (ITRS). For a subset of cases (n = 29), cellular composition of the tumour bed was analysed by flow cytometry., Results: There was strong interobserver reproducibility in assessment of pathological response (κ = 0.879) and percentage residual viable melanoma (intraclass correlation coefficient = 0.965). The immunotherapeutic response subtype with high fibrosis had the strongest association with lack of recurrence (P = 0.008) and prolonged RFS (P = 0.019). Amongst patients with criteria for pathological non-response (pNR, >50% viable tumour), all who recurred had ≥70% viable melanoma. Higher ITRS and irPR scores correlated with lack of recurrence in the entire cohort (P = 0.002 and P ≤ 0.0001). The number of B lymphocytes was significantly increased in patients with a high fibrosis subtype of treatment response (P = 0.046)., Conclusions: There is strong reproducibility for assessment of pathological response using INMC criteria. Immunotherapeutic response of fibrosis subtype correlated with improved RFS, and may represent a biomarker. Potential B-cell contribution to fibrosis development warrants further study. Reclassification of pNR to a threshold of ≥70% viable melanoma and incorporating additional criteria of <10% fibrosis subtype of response may identify those at highest risk of recurrence, but requires validation., Competing Interests: Disclosure EAR received travel support from Merck Sharpe & Dohme (MSD) and NanoString. AMM reports personal fees as a consultant advisor for Bristol Myers Squibb (BMS), MSD, Novartis, Roche, Pierre Fabre and QBiotics. ACJvA reports personal fees as a consultant advisor for Amgen, BMS, Novartis, MSD Merck, Merck–Pfizer, Sanofi and 4SC, and received grant support from Amgen, BMS and Novartis all paid to the institution (The Netherlands Cancer Institute). ADG received travel support from Merck KgA and Sun Pharma and has served as a consultant advisor for BMS, Pfizer, Merck KgA, Regeneron and Sun Pharma. MTT reports Advisory Board with Merck, Myriad Genetics, Novartis, Seattle Genetics and NanoString. RPMS has received honoraria for advisory board participation from MSD, Novartis and QBiotics and speaking honoraria from BMS. AJS has received honoraria for advisory board participation from QBiotics and Stryker. CUB reports personal fees as a consultant advisor for BMS, MSD, Roche, Novartis, Lilly, Pfizer, GSK, GenMab and Pierre Fabre for which the institution (The Netherlands Cancer Institute) received funding, has received research grants from BMS, Novartis and NanoString all paid to the institution (The Netherlands Cancer Institute), is shareholder of Unity Cars and co-founder of Immagene BV and received personal compensation as consultant advisor from Third Rock Ventures. GVL reports personal fees as a consultant advisor to Aduro Biotech Inc, Amgen Inc, Array Biopharma Inc, Boehringer Ingelheim International GmbH, BMS, Highlight Therapeutics S.L., MSD, Novartis Pharma AG, QBiotics Group Limited, Regeneron Pharmaceuticals Inc, and SkylineDx B.V. (all not related to this work). BAvdW reports advisory role for BMS. RAS has received professional services fees from QBiotics, Merck Sharp Dohme, BMS, Novartis, GlaxoSmithKline, Myriad and NeraCare (not related to this work). WJvH reports personal fees as a consultant advisor for Amgen and Sanofi. JH received (institutional fees for advisory roles in Achilles Tx, BioNTech, BMS, Ipsen, Immunocore, MSD, Merck Serono, Molecular Partners, PokeAcel, Pfizer, Roche, Sanofi, T-knife, Third Rock Ventures. JH received personal fees for advisory role in Neogene Tx. JH received institutional grant support from Amgen, BioNTech US, BMS, MSD, Neogene Therapeutics, Novartis. All other authors have declared no conflicts of interest., (Copyright © 2021 European Society for Medical Oncology. All rights reserved.)

Desmoplastic melanomas are uncommon. Their behaviour differs from that of other melanoma subtypes; therefore, management guidelines for non-desmoplastic melanomas may not be applicable. This review sought to examine all available evidence relating to the behaviour and management of desmoplastic melanomas, based on review of all relevant English-language publications, and to critically assess the recommendations for their management in current published melanoma management guidelines. Compared with other melanoma subtypes, patients with 'pure' desmoplastic melanomas (where ≥90% of the invasive melanoma is of desmoplastic melanoma subtype) have much lower rates of sentinel node positivity and distant metastasis. Local recurrence rates are higher for desmoplastic melanomas, but resection margins wider than those recommended for non-desmoplastic melanomas have not been shown to be of benefit. Adjuvant radiotherapy reduces the risk of local recurrence when a satisfactory histological clearance (≥8 mm) cannot be achieved. Of 29 published melanoma management guidelines identified, only 11 specified management for desmoplastic melanomas, while seven simply stated that the feature should be reported. Desmoplastic melanoma is a unique melanoma subtype with biology that differs from that of other melanoma subtypes. It requires specific management strategies but few current guidelines address these., (© 2021 European Academy of Dermatology and Venereology.)