Neoadjuvant Nivolumab and Ipilimumab in Resectable Stage III Melanoma.

BACKGROUND: Phase 1-2 trials involving patients with resectable, macroscopic stage III melanoma have shown that neoadjuvant immunotherapy is more efficacious than adjuvant immunotherapy. METHODS: In this phase 3 trial, we randomly assigned patients with resectable, macroscopic stage III melanoma, in a 1:1 ratio, to receive two cycles of neoadjuvant ipilimumab plus nivolumab and then undergo surgery or to undergo surgery and then receive 12 cycles of adjuvant nivolumab. Only the patients in the neoadjuvant group who had a partial response or nonresponse received subsequent adjuvant treatment. The primary end point was event-free survival. RESULTS: A total of 423 patients underwent randomization. At a median follow-up of 9.9 months, the estimated 12-month event-free survival was 83.7% (99.9% confidence interval [CI], 73.8 to 94.8) in the neoadjuvant group and 57.2% (99.9% CI, 45.1 to 72.7) in the adjuvant group. The difference in restricted mean survival time was 8.00 months (99.9% CI, 4.94 to 11.05; P<0.001; hazard ratio for progression, recurrence, or death, 0.32; 99.9% CI, 0.15 to 0.66). In the neoadjuvant group, 59.0% of the patients had a major pathological response, 8.0% had a partial response, 26.4% had a nonresponse (>50% residual viable tumor), and 2.4% had progression; in 4.2%, surgery had not yet been performed or was omitted. The estimated 12-month recurrence-free survival was 95.1% among patients in the neoadjuvant group who had a major pathological response, 76.1% among those who had a partial response, and 57.0% among those who had a nonresponse. Adverse events of grade 3 or higher that were related to systemic treatment occurred in 29.7% of the patients in the neoadjuvant group and in 14.7% in the adjuvant group. CONCLUSIONS: Among patients with resectable, macroscopic stage III melanoma, neoadjuvant ipilimumab plus nivolumab followed by surgery and response-driven adjuvant therapy resulted in longer event-free survival than surgery followed by adjuvant nivolumab. (Funded by Bristol Myers Squibb and others; NADINA ClinicalTrials.gov number, NCT04949113.).

Melanomas in children and adolescents: Clinicopathologic features and survival outcomes.

BACKGROUND: Melanomas in the first 2 decades of life are uncommon and poorly understood. OBJECTIVE: To assess clinicopathologic features and survival of children (≤11 years) and adolescents (12-19 years) diagnosed with melanoma. METHODS: A pooled cohort of 514 patients was analyzed (397 Dutch, 117 Australian; 62 children, 452 adolescents). Pathology reports were reevaluated to determine melanoma subtypes. Multivariable Cox models were generated for recurrence-free survival (RFS) and overall survival (OS). RESULTS: Melanoma subtypes were conventional melanoma (superficial spreading, nodular, desmoplastic, and acral lentiginous), spitzoid melanoma, and melanoma associated with a congenital nevus in 428, 78, and 8 patients, respectively. Ten-year RFS was 91.5% (95% confidence interval [CI], 82.4%-100%) in children and 86.4% (95% CI, 82.7%-90.3%) in adolescents (P = .32). Ten-year OS was 100% in children and 92.7% (95% CI, 89.8%-95.8%) in adolescents (P = .09). On multivariable analysis possible only for the adolescent cohort due to the small number of children, ulceration status, and anatomic site were associated with RFS and OS, whereas age, sex, mitotic index, sentinel node status and melanoma subtype were not. Breslow thickness >4 mm was associated with worse RFS. LIMITATIONS: Retrospective study. CONCLUSIONS: Survival rates for children and adolescents with melanomas were high. Ulceration, head or neck location and Breslow thickness >4 mm predicted worse survival in adolescents.

In vivo reflectance confocal microscopy can detect the invasive component of lentigo maligna melanoma: Prospective analysis and case-control study.

BACKGROUND: Lentigo maligna (LM), a form of melanoma in situ, has no risk of causing metastasis unless dermal invasive melanoma (LMM) supervenes. Furthermore, the detection of invasion impacts prognosis and management. OBJECTIVE: To assess the accuracy of RCM for the detection of invasion component on LM/LMM lesions. METHODS: In the initial case-control study, the performance of one expert in detecting LMM at the time of initial RCM assessment of LM/LMM lesions was recorded prospectively (n = 229). The cases were assessed on RCM-histopathology correlation sessions and a panel with nine RCM features was proposed to identify LMM, which was subsequently tested in a subset of initial cohort (n = 93) in the matched case-control study by two blinded observers. Univariable and multivariable logistic regression models were performed to evaluate RCM features predictive of LMM. Reproducibility of assessment of the nine RCM features was also evaluated. RESULTS: A total of 229 LM/LMM cases evaluated by histopathology were assessed blindly and prospectively by an expert confocalist. On histopathology, 210 were LM and 19 were LMM cases. Correct identification of an invasive component was achieved for 17 of 19 LMM cases (89%) and the absence of a dermal component was correctly diagnosed in 190 of 210 LM cases (90%). In the matched case-control (LMM n = 35, LM n = 58), epidermal and junctional disarray, large size of melanocytes and nests of melanocytes were independent predictors of LMM on multivariate analysis. The interobserver analysis demonstrated that these three features had a fair reproducibility between the two investigators (K = 0.4). The multivariable model including those three features showed a high predictive performance AUC = 74% (CI 95% 64-85%), with sensitivity of 63% (95% CI 52-78%) and specificity of 79% (CI 95% 74-88%), and likelihood ratio of 18 (p-value 0.0026). CONCLUSION: Three RCM features were predictive for identifying invasive melanoma in the background of LM.

The progressive relationship between increasing Breslow thickness and decreasing survival is lost in patients with ultrathick melanomas (≥15 mm in thickness).

BACKGROUND: Survival tends to decrease as the Breslow thickness of a primary melanoma increases. However, little is known about the prognostic value of Breslow thickness in patients with very thick melanomas. OBJECTIVE: We sought to assess survival in patients with melanomas ≥4.0 mm in Breslow thickness. METHODS: A pooled cohort of 5595 patients (4107 Dutch and 1488 Australian) with melanomas ≥4.0 mm in thickness diagnosed from 2000 to 2014 was analyzed. Standard and spline Cox regressions were generated for overall survival (OS) and recurrence-free survival (RFS). RESULTS: The median follow-up was 3.4 years. The continuous hazard ratios (HRs) for OS and RFS increased steadily as the Breslow thickness increased to 15 mm, stabilized up to 20 mm, and decreased thereafter. Using patients with melanomas 4 to <10 mm thick as a reference group, the categoric HR for OS increased up to the 15- to -<20-mm thickness category and then decreased (HR, 1.46 [95% CI, 1.29-1.66], P < .0001 for 10-<15 mm; HR, 1.97 [95% CI, 1.55-2.51], P < .0001 for 15-<20 mm; and HR, 1.36 [95% CI, 1.07-1.84], P = .045 for ≥20 mm). For the RFS, similar trends were observed. LIMITATIONS: Retrospective study. Small cohorts of patients with melanomas 15-<20mm and ≥20mm. CONCLUSION: The progressive relationship between increasing Breslow thickness and decreasing survival is lost in patients with melanomas ≥15 mm in thickness.

Road to Metastasis: The TWEAK Pathway as a Discriminant between Metastasizing and Non-Metastasizing Thick Melanomas.

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.

Melanoma pathology reporting and staging.

The pathological diagnosis of melanoma can be challenging. The provision of an appropriate biopsy and pertinent history can assist in establishing an accurate diagnosis and reliable estimate of prognosis. In their reports, pathologists should document both the criteria on which the diagnosis was based as well as important prognostic parameters. For melanoma, such prognostic parameters include tumor thickness, ulceration, mitotic rate, lymphovascular invasion, neurotropism, and tumor-infiltrating lymphocytes. Disease staging is important for risk stratifying melanoma patients into prognostic groups and patient management recommendations are often stage based. The 8th edition American Joint Committee on Cancer (AJCC) Melanoma Staging System was implemented in 2018 and several important changes were made. Tumor thickness and ulceration remain the key T category criteria. T1b melanomas were redefined as either ulcerated melanomas <1.0 mm thick or nonulcerated melanomas 0.8-1.0 mm thick. Although mitotic rate was removed as a T category criterion in the 8th edition, it remains a very important prognostic factor and should continue to be documented in primary melanoma pathology reports. It was also recommended in the 8th edition that tumor thickness be recorded to the nearest 0.1 mm (rather than the nearest 0.01 mm). In the future, incorporation of additional prognostic parameters beyond those utilized in the current version of the staging system into (web based) prognostic models/clinical tools will likely facilitate more personalized prognostic estimates. Evaluation of molecular markers of prognosis is an active area of current research; however, additional data are needed before it would be appropriate to recommend use of such tests in routine clinical practice.

The prognostic significance of microsatellites in cutaneous melanoma.

Microscopic satellite metastases are an adverse prognostic feature in primary cutaneous melanoma patients. The prognostic significance of microsatellites, including their number, size and distance from the primary melanoma, using the 8th edition American Joint Committee on Cancer definition, has not previously been evaluated. This study sought to determine the prognostic significance of microsatellites in histopathologically reviewed cases. Eighty-seven cases of primary cutaneous melanoma with the presence of microsatellites documented in the original pathology report and all histopathology slides available were reviewed and the findings were correlated with clinical outcome. Matched control cases were selected for all confirmed microsatellites cases. The presence of microsatellites was confirmed in 69 cases. The microsatellite group had significantly worse prognosis, with 21% 5-year disease-free survival compared with 56% in the control group (p < 0.001). The 5-year melanoma-specific survival was 53% in the microsatellites group and 73% in the control group (p = 0.004). Increasing distance (mm) of the microsatellite from the primary melanoma was found to adversely influence disease-free survival (HR = 1.24, 95% CI: 1.13-1.36, p < 0.001), overall survival (HR = 1.26 95%CI: 1.13-1.40, p < 0.001), and melanoma-specific survival (HR = 1.27 95% CI: 1.11-1.45, p < 0.001). Number and size of microsatellites were not significant prognostic factors. The presence of microsatellites was the only factor that proved to be an independent predictor of sentinel node positivity in multivariate analysis (OR 4.64; 95% CI 1.66-12.95; p = 0.003). Microsatellites were significantly associated with more loco-regional recurrences (p < 0.001) but not distant metastases (p = 0.821). Melanomas with microsatellites as defined by the 8th edition American Joint Committee on Cancer staging system are thus aggressive tumors, associated with significantly worse disease-free survival, overall survival and melanoma-specific survival. The presence of microsatellites is also associated with sentinel node-positivity and local and in-transit recurrence. Increasing distance of the microsatellite from the primary tumor is an independent adverse prognostic factor that warrants further evaluation.

Neoadjuvant dabrafenib combined with trametinib for resectable, stage IIIB-C, BRAFV600 mutation-positive melanoma (NeoCombi): a single-arm, open-label, single-centre, phase 2 trial.

BACKGROUND: Adjuvant dabrafenib plus trametinib therapy improves relapse-free survival in patients with resected stage III melanoma. We aimed to ascertain the proportion of patients who would have a pathological response and a response according to Response Evaluation Criteria in Solid Tumors (RECIST) after neoadjuvant dabrafenib plus trametinib therapy for resectable clinical stage III melanoma. METHODS: NeoCombi was a single-arm, open-label, single-centre, phase 2 study done at Melanoma Institute Australia (Sydney, NSW, Australia). Eligible patients were adults (aged ≥18 years) with histologically confirmed, resectable, RECIST-measurable, clinical stage IIIB-C (American Joint Committee on Cancer [AJCC] 7th edition), BRAFV600-mutant melanoma, and had an Eastern Cooperative Oncology Group performance status of 1 or lower. Patients received 150 mg dabrafenib orally, twice daily, plus 2 mg trametinib orally, once daily, for 52 weeks (12 weeks of neoadjuvant therapy before complete resection of the pre-therapy tumour bed, and 40 weeks of adjuvant therapy thereafter). CT and PET scans were done at baseline and before resection. The primary outcomes were the proportion of patients achieving a complete pathological response and the proportion of patients achieving a response according to RECIST at week 12, analysed as per protocol. This trial is registered with ClinicalTrials.gov, NCT01972347, and follow-up of patients is ongoing. FINDINGS: Between Aug 20, 2014, and April 19, 2017, 40 patients were screened, of whom 35 eligible patients were enrolled, received neoadjuvant dabrafenib plus trametinib, and underwent resection. At the data cutoff (Sept 24, 2018), median follow-up was 27 months (IQR 21-36). At resection, 30 (86%) patients achieved a RECIST response; 16 (46%; 95% CI 29-63) had a complete response and 14 (40%; 24-58) had a partial response. Five patients (14%; 95% CI 5-30) had stable disease, and no patients progressed. After resection and pathological evaluation, all 35 patients achieved a pathological response, of whom 17 (49%; 95% CI 31-66) patients had a complete pathological response and 18 (51%; 95% CI 34-69) had a non-complete pathological response. Treatment-related serious adverse events occurred in six (17%) of 35 patients and grade 3-4 adverse events occurred in ten (29%) patients. No treatment-related deaths were reported. INTERPRETATION: Neoadjuvant dabrafenib plus trametinib therapy could be considered in the management of RECIST-measurable resectable stage III melanoma as it led to a high proportion of patients achieving a complete response according to RECIST and a high proportion of patients achieving a complete pathological response, with no progression during neoadjuvant therapy. FUNDING: GlaxoSmithKline; Novartis; National Health and Medical Research Council, Australia; and Melanoma Institute Australia.

Unexpected UVR and non-UVR mutation burden in some acral and cutaneous melanomas.

Ultraviolet radiation (UVR) mutagenesis causes nearly all cutaneous melanomas, however, since UVR signatures are largely absent in acral melanoma, as well as melanoma in sun-protected sites, the cause of these melanomas is unknown. Whole-genome sequencing data generated as part of the Australian Melanoma Genome Project was supplemented with a detailed histopathological assessment with the melanomas then classified as UVR or non-UVR related, based on their mutation signatures. The clinicopathological characteristics of melanomas with mutation signatures for their subtype were compared. Three (of 35=8.6%) acral melanomas, all clinically and pathologically verified as arising from acral or subungual locations, had predominant UVR mutation burden, whereas four (of 140=2.9%) cutaneous melanomas showed predominant non-UVR mutations. Among the acral melanomas, the few that were UVR dominant occurred in younger patients, had a higher mutation load and a proportion of mutation burden due to UVR, which was similar to that in melanomas from intermittently UVR-exposed skin. Acral melanomas with a UVR signature occurred most frequently in subungual sites and included tumors harboring BRAF or NF1 mutations. Cutaneous melanomas dominated by non-UVR signatures had lower mutation burdens counts and their primary tumors were thicker and had more mitoses than in other cutaneous melanomas. No histopathological features predicted UVR dominance in acral melanomas or non-UVR dominance in cutaneous melanomas. Our finding of acral/subungual melanomas with predominant UVR mutagenesis suggests that the nail plate and acral skin do not provide complete protection from UVR. Our data also confirm that cutaneous melanomas not caused by UVR are infrequent. Identifying where mutation burden is discordant with primary tumor anatomical site is likely to be clinically significant when determining treatment options for metastatic acral and cutaneous melanoma patients.

Molecular and clinical correlates of HER3 expression highlights its potential role as a therapeutic target in melanoma.

Overexpression of the epidermal growth factor receptor family member HER3 (erbB3) has been implicated in several types of cancer and recently drugs targeting HER3 have shown promising clinical activity. In melanoma, HER3 overexpression has been linked to both metastasis formation and resistance to drug therapy in cell culture models. Here, we sought to characterise the expression of HER3 in 187 melanoma biopsies (149 cutaneous, 38 mucosal) using immunohistochemistry, as well as to analyse the association between HER3 expression and molecular, clinical and pathological variables. A subset of the cutaneous melanoma specimens was taken prior to treatment with immune checkpoint blockade therapy (pre-ICB) (n=79). HER3 expression (≥1+) was observed in 136 of 187 samples (∼73%). HER3 expression was found to be markedly lower in the mucosal melanomas, with 17 of the 38 tumours (∼45%) demonstrating no HER3 expression. In cutaneous melanomas, there was a negative association between HER3 expression and mutational load, a positive association with NRAS mutational status, and a trend of negative association with PD-L1 expression. In the pre-ICB cohort, an association was found between high HER3 expression (≥2+) and overall survival after anti-PD-1-based immunotherapy. Overall, our results indicate that HER3 is a promising therapeutic avenue in cutaneous melanoma worthy of further clinical evaluation.

Inter-rater concordance of basal cell carcinoma subtypes: influences on reporting format and opportunities for further classification modifications.

Diagnosis of basal cell carcinoma (BCC) higher risk subtypes influences management strategies because of their propensity to recur locally. Subtyping is prone to inter-observer variability, and subtyping definitions are inconsistently applied. This study sought to compare the interobserver reproducibility of individual BCC subtypes using the 4th edition World Health Organization (WHO) Classification of Skin Tumours (CoST) definitions, with classification into lower and higher risk histological subtype groups. Ninety-one BCC cases were rated by seven pathologists, noting the presence of BCC subtype(s), and providing a higher or lower risk subtype grouping per case. Raters were provided with definitions as per the 4th edition WHO CoST for 10 listed BCC subtypes. Surgical specimen type was noted. Subgroup analysis was performed to exclude cases when the tumour deep front was not well visualised, or there was tangential sectioning (n = 6). Light's kappa was used to assess inter-rater reliability. From the total group (n = 91), five BCC subtypes showed a sufficient number of ratings for computing a κ statistic. From these five subtypes, superficial subtype showed substantial inter-rater agreement (κ = 0.64), and the other four subtypes showed moderate inter-rater agreement [nodular (κ = 0.45), sclerosing/morphoeic (κ = 0.45), infiltrating (κ = 0.49) and micronodular (κ = 0.57)]. Two-tiered rating into either higher or lower risk subtype showed substantial inter-rater agreement (κ = 0.72). Our results suggest a need to more precisely define BCC subtypes. We suggest reporting BCC subtype using a two-tiered risk grouping, followed by specific subtypes present. Further studies examining the inter-rater reliability of less common BCC subtypes are required.

IFN-γ signature enables selection of neoadjuvant treatment in patients with stage III melanoma.

Neoadjuvant ipilimumab + nivolumab has demonstrated high pathologic response rates in stage III melanoma. Patients with low intra-tumoral interferon-γ (IFN-γ) signatures are less likely to benefit. We show that domatinostat (a class I histone deacetylase inhibitor) addition to anti-PD-1 + anti-CTLA-4 increased the IFN-γ response and reduced tumor growth in our murine melanoma model, rationalizing evaluation in patients. To stratify patients into IFN-γ high and low cohorts, we developed a baseline IFN-γ signature expression algorithm, which was prospectively tested in the DONIMI trial. Patients with stage III melanoma and high intra-tumoral IFN-γ scores were randomized to neoadjuvant nivolumab or nivolumab + domatinostat, while patients with low IFN-γ scores received nivolumab + domatinostat or ipilimumab + nivolumab + domatinostat. Domatinostat addition to neoadjuvant nivolumab ± ipilimumab did not delay surgery but induced unexpected severe skin toxicity, hampering domatinostat dose escalation. At studied dose levels, domatinostat addition did not increase treatment efficacy. The baseline IFN-γ score adequately differentiated patients who were likely to benefit from nivolumab alone versus patients who require other therapies.

Diagnostic utility of PRAME, p53 and 5-hmC immunostaining for distinguishing melanomas from naevi, neurofibromas, scars and other histological mimics.

High expression of PRAME (PReferentially expressed Antigen in MElanoma) and p53 (a proposed marker of desmoplastic melanoma) and low expression of 5-hydroxymethylcytosine (5-hmC) have each been reported in melanoma. However, their combined diagnostic utility for distinguishing melanomas, including uncommon variants, from histological mimics is unknown. This study sought to determine the utility of PRAME, p53 and 5-hmC immunostains for diagnosing melanocytic tumours. A total of 333 cutaneous melanocytic tumours (melanoma n=280, naevi n=53), 20 cutaneous neurofibromas, and 15 scars were evaluated using multiplex immunofluorescence (n=313) or single-plex chromogenic immunohistochemical staining (n=55). Immunostaining for PRAME and 5-hmC were each scored using a previously described semiquantitative scale 0 (absent) to 4+ (diffuse). p53 was scored using a previously described immunoreactive score (range 0-300). PRAME expression was significantly higher in melanomas than in naevi (p<0.0001), with the lowest PRAME expression found in low-grade desmoplastic melanomas compared to the other melanoma subtypes. In non-desmoplastic melanomas, 38% showed 4+ staining (>75% positive tumour cells) and 70% showed 3+ or 4+(>50% positive tumour cells). Conversely, 96% of naevi showed 0, 1+ or 2+ expression. 5-hmC expression was significantly lower in melanomas than in naevi (p<0.0001). However, acral melanomas were not significantly associated with loss of 5-hmC expression (p=0.84). Compared with using PRAME in isolation, combining PRAME and 5-hmC scores increased sensitivity (64%-84%) for detecting melanoma. With respect to desmoplastic melanoma compared to scar or neurofibroma, strong PRAME or p53 staining were almost exclusively found in high-grade desmoplastic melanomas; low-grade desmoplastic melanomas, neurofibromas and scars were negative. 5-hmC was not useful in distinguishing desmoplastic melanomas from neurofibromas or scars. Our data support the use of PRAME as a highly specific ancillary investigation in the diagnosis of melanoma, however PRAME should be considered 'positive' if there is 3+ or 4+ staining (rather than the widely recommended 4+ threshold). 5-hmC, PRAME and p53 appear to have a limited role in the diagnosis of low-grade desmoplastic melanomas.

Comprehensive Clinical, Histopathologic, and Molecular Analysis and Long-term Follow-up of Patients With Nodal Blue Nevi.

Blue nevi are benign, melanocytic neoplasms that show a range of clinical and morphologic patterns and include common/dendritic, cellular, and atypical cellular subtypes. Like other nevi, they most commonly occur in skin but can occasionally involve lymph nodes where they may be misinterpreted as representing metastatic melanoma. Moreover, whether benign blue nevi can metastasize to lymph nodes and their natural history and prognostic significance has been the subject of great controversy. To date, few cases of nodal blue nevi have been reported in the literature, and those reports have had limited clinical follow-up and supporting molecular data. This study sought to determine the clinical, pathologic, and molecular features of blue nevi involving lymph nodes, clarify their clinical significance, provide evidence for understanding their pathogenesis, and highlight potential pitfalls in the interpretation of lymph nodes with an ultimate aim of improving patient care. Thirteen cases of blue nevi involving lymph nodes were identified in the archives of Royal Prince Alfred Hospital, Sydney, Australia (1984-2018). A detailed assessment of the clinical and pathologic features of each case was performed, including an evaluation of all available immunohistochemical stains. Extended clinical follow-up was available for 9 patients. Droplet digital polymerase chain reaction for GNAQ Q209L, Q209P and GNA11 Q209L mutations was performed on 7 cases of blue nevi within lymph nodes together with matching cutaneous (presumed primary) blue nevi in 2 cases. All cases showed typical histologic features of blue nevi. BAP1 was retained in all cases (n=7). There were no recurrence or metastasis of blue nevus in any case on long-term clinical follow-up (n=9, median follow-up, 12 y). The majority of cases (n=5 of 7 evaluated) had GNAQ and GNA11 driver mutations. The 2 patients with a matched primary cutaneous blue nevus and regionally associated nodal blue nevus had the same GNAQ Q209L mutation in both sites in each patient. We conclude that blue nevi can involve lymph nodes and are associated with benign clinical behavior, and probably represent so-called "benign" metastasis. Awareness of these lesions is important when evaluating lymph nodes to avoid misdiagnosis as metastatic melanoma.

Pathologist initiated reflex BRAF mutation testing in metastatic melanoma: experience at a specialist melanoma treatment centre.

Testing for BRAF mutations in metastatic melanoma is pivotal to identifying patients suitable for targeted therapy and influences treatment decisions regarding single agent versus combination immunotherapy. Knowledge of BRAF V600E immunohistochemistry (IHC) results can streamline decisions during initial oncology consultations, prior to DNA-based test results. In the absence of formal guidelines that require pathologist initiated ('reflex') BRAF mutation testing, our institution developed a local protocol to perform BRAF V600E IHC on specimens from all stage III/IV melanoma patients when the status is otherwise unknown. This study was designed to evaluate the application of this protocol in a tertiary referral pathology department. A total of 408 stage III/IV melanoma patients had tissue specimens accessioned between 1 January and 31 March in three consecutive years (from 2019 to 2021), reported by 32 individual pathologists. The BRAF mutation status was established by pathologists in 87% (352/408) of cases. When a prior BRAF mutation status was previously known, as confirmed in linked electronic records (202/408), this status had been communicated by the clinician on the pathology request form in 1% of cases (3/202). Pathologists performed BRAF V600E IHC in 153 cases (74% of cases where the status was unknown, 153/206) and testing was duplicated in 5% of cases (20/408). Reflex BRAF IHC testing was omitted in 26% of cases (53/206), often on specimens with small volume disease (cytology specimens or sentinel node biopsies) despite adequate tissue for testing. Incorporating BRAF IHC testing within routine diagnostic protocols of stage III/IV melanoma was both feasible and successful in most cases. Communication of a patient's BRAF mutation status via the pathology request form will likely improve implementation of pathologist initiated BRAF mutation testing and may result in a reduction of duplicate tests. To improve pathologist reflex testing rates, we advocate for the use of an algorithmic approach to pathologist initiated BRAF mutation testing utilising both IHC and DNA-based methodologies for stage III/IV melanoma patients.

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

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

Distinct pretreatment innate immune landscape and posttreatment T cell responses underlie immunotherapy-induced colitis.

Immune-related adverse events represent a major hurdle to the success of immunotherapy. The immunological mechanisms underlying their development and relation to antitumor responses are poorly understood. By examining both systemic and tissue-specific immune changes induced by combination anti-CTLA-4 and anti-PD-1 immunotherapy, we found distinct repertoire changes in patients who developed moderate-severe colitis, irrespective of their antitumor response to therapy. The proportion of circulating monocytes were significantly increased at baseline in patients who subsequently developed colitis compared with patients who did not develop colitis, and biopsies from patients with colitis showed monocytic infiltration of both endoscopically and histopathologically normal and inflamed regions of colon. The magnitude of systemic expansion of T cells following commencement of immunotherapy was also greater in patients who developed colitis. Importantly, we show expansion of specific T cell subsets within inflamed regions of the colon, including tissue-resident memory CD8+ T cells and Th1 CD4+ T cells in patients who developed colitis. Our data also suggest that CD8+ T cell expansion was locally induced, while Th1 cell expansion was systemic. Together, our data show that exaggerated innate and T cell responses to combination immunotherapy synergize to propel colitis in susceptible patients.

Representativeness of the Index Lymph Node for Total Nodal Basin in Pathologic Response Assessment After Neoadjuvant Checkpoint Inhibitor Therapy in Patients With Stage III Melanoma.

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.