Background and Objectives: Talimogene laherparepvec (T-VEC) is an intralesional cancer immunotherapy in patients with unresectable stage IIIB-IV melanoma and Merkel cell carcinoma (MCC). This study assesses T-VEC outcomes in patients with in-transit melanoma and MCC refractory to anti-PD-1 blockade. Methods: All patients with advanced melanoma or MCC with >= 1 measurable lesion(s) were retrospectively evaluated from 2019 to 2023. Only those who received ICI therapy for >= 3 months with progression of regional metastasis prior to receiving T-VEC were included. Clinicopathologic and treatment data were reviewed. Results: Seventeen patients underwent T-VEC therapy, consisting of thirteen melanoma and four MCC cases. Median age was 75.9 and 79.6 for melanoma and MCC cases respectively. Eleven melanoma (84 %) and three MCC (75 %) cases received extremity injections. Median number of in-transit metastatic sites for melanoma and MCC were 4 and 10; respectively, and the median number of treatment cycles per patient was five in both groups. Ten total patients responded with 8 complete responses and 2 partial responses, while five (4 melanoma; 1 MCC) had disease progression. Of seventeen patients, two discontinued T-VEC due to grade 3 + adverse events. Conclusion: T-VEC following or in conjunction with immunotherapy exhibits tolerability and potential benefit in patients with advanced MCC and melanoma.

INTRODUCTION:Asian American and Native Hawaiian-Pacific Islanders (AAPI) are the fastest growing racial-ethnic group, with 18.9 million people in 2019, and is predicted to rise to 46 million by 2060. Colorectal cancer (CRC) is the most common cancer in AAPI men and the third most common in women. Treatment techniques like laparoscopic colectomy (LC) emerged as the standard of care for CRC resections; however, new robotic technologies can be advantageous. Few studies have compared clinical outcomes across minimally invasive approaches for AAPI patients with CRC. This study compares utilization and clinical outcomes of LC versus robotic colectomies (RCs) in AAPI patients. METHODS:We queried the American College of Surgeons National Surgical Quality Improvement Program database for elective RC and LC in AAPI patients from 2012 to 2020. Outcomes included unplanned conversion to open, operative time, complications, 30-d mortality, and length of stay. Multivariable logistic regression analyses assessed the association between outcomes and the operative approach. RESULTS:Between 2012 and 2020, 83,841 patients underwent elective LC or RC. Four thousand six hundred fifty-eight AAPI patients underwent 3817 (82%) LCs and 841 (18%) RCs. In 2012, all procedures were performed laparoscopically; by 2020, 27% were robotic. Mean operative time was shorter in LC (192 versus 249 min, P < 0.001). On multivariable logistic regression, there was no difference in infection (odds ratio [OR] 0.8, 95% confidence interval [CI] 0.59-1.12), anastomotic leak (OR 0.97, 95% CI 0.59-1.61), or death (OR 0.9, 95% CI 0.31-2.61). Length of stay was shorter for RC (-0.44 d, 95% CI -0.71 to -0.18 d). CONCLUSIONS:Overall, AAPI postoperative outcomes are similar between LC and RC. Future studies that evaluate costs and resource utilization can assist hospitals in determining whether implementing robotic-assisted technologies in their hospitals and communities will be appropriate.

Relative Value Units (RVUs) are utilized to measure physician work effort and create national benchmarks. Physicians are often measured against national benchmarks to determine compensation. Using a case study in cytoreductive surgery, we explored variability in coding that can impact national benchmarks. A survey was conducted amongst surgeons in the peritoneal surface malignancies consortium (PSM). Data was collected on clinical experience, clinical full time equivalent, wRVUS and institutional coding practice. Coding of the same procedure resulted in significantly varying RVUs (IQR 60-101) across institutions. Higher volume (> 50

Atherosclerotic plaques form primarily in the coronary and carotid arteries, the aorta, and peripheral arteries of the lower extremities. Although a common model of atherogenesis across these arteries has evolved over decades, there is limited understanding of important differences in regional atherosclerotic disease. We sought to explore the relation between these disease groups by performing a retrospective study evaluating the temporal pattern of ASCVD patients with a diagnosis of cerebrovascular disease (CeVD), coronary artery disease (CAD), or peripheral arterial disease (PAD). An IRB-approved retrospective chart review was performed on a regional health system database. Records were obtained for all patients from 2012-2023 with ICD-10 diagnosis for CeVD, CAD, and PAD, including subcategory codes. The review identified 119,320 patients older than 50 years at an initial diagnosis. Diagnosis date and demographics were then used to evaluate the incidence and temporal relationship of subsequent disease. Fig 1 shows the distribution of disease by age group. The majority of patients (74%) had CAD. CAD alone was present in 45%, while a combination of CAD with PAD or CeVD (doublets) occurred in 9% and 14%, respectively. In patients with doublets, CAD manifested prior to CeVD in 54% and prior to PVD in 78%. Fig 2 shows the diagnostic sequence of disease in patients with all three diseases (7%; triplets). CAD is the first to manifest in 59% of the patients. CAD is more prevalent than CeVD or PAD in patients with ASCVD. CAD is the dominant disease either alone or in combination with CeVD or PAD. CAD also seems to manifest earlier than CeVD or PAD. This study emphasizes the importance of close management and surveillance of patients that present with CAD as this is a marker for subsequent disease in other vascular beds.Fig 2Triplets by diagnostic sequence.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

PURPOSE High-grade appendiceal adenocarcinomas (HGAA) with peritoneal metastases (PMs) are associated with poor survival. Hyperthermic intraperitoneal chemotherapy (HIPEC) is a novel treatment approach for unresectable HGAA-PM. However, its influence on immunogenomic profiles has not yet been fully explored. MATERIALS AND METHODS We obtained 79 samples of metastatic peritoneal tumor deposits from patients diagnosed with HGAA and performed whole-exome sequencing, RNA sequencing, and immunoprofiling before and after HIPEC. Tumor biopsies were subjected to immunogenomic profiling to detect mutational signatures and immune populations associated with oncologic outcomes. RESULTS Fifteen patients with HGAA-PMs were included in the study. The median progression-free survival (PFS) was 6.7 months (2.7-25.3) and the median overall survival was 11.4 months (4.7-42). Mucin-associated genes ( MUC16, MUC3A, and MUC5AC) and titin ( TTN) had the highest mutation frequencies. Mutational signatures such as single-base substitution 29 and doublet-base substitution 11 were present in >50% of single-base and double-base mutations. Higher PD-L1 coexpression on CD8+ T cells demonstrated a higher PFS both intratumorally ( P = .019) and at the margin ( P = .025). CONCLUSION HIPEC-associated mutational signatures were identified in HGAA-PMs. Elevated PD-L1+ cytotoxic T-cell populations after HIPEC had better PFS, offering valuable insights for prognostication in the context of HIPEC treatment.

PURPOSE Melanocortin-1 receptor (MC1R) plays a critical role in human pigmentation and DNA repair mechanisms. MC1R-targeting agents are being investigated in clinical trials in patients with melanoma, yet large studies investigating the rate and degree of MC1R expression in primary and metastatic human melanoma tissue are lacking. METHODS Using tissue microarrays containing three large cohorts of 225 cases of benign nevi, 189 with primary melanoma, and 271 with metastatic melanoma, we applied quantitative immunofluorescence and immunohistochemistry to comprehensively study MC1R protein expression. RESULTS We show a stepwise elevation of MC1R expression in different stages of melanoma progression (nevi, primary, metastasis). Higher MC1R expression was seen in deeper (>1 mm) primary lesions and ulcerated lesions and was associated with shorter survival in primary and metastatic tumors. On multivariable analysis, Breslow thickness, male sex, and chronic sun exposure were independent predictors of worse overall survival in the primary melanoma cohort. CONCLUSION Our data suggest that MC1R might be a valuable drug target in aggressive melanoma. Additional studies are warranted to determine its functional significance in melanoma progression and its utility as a predictive biomarker in patients receiving MC1R-directed therapies.

Background: There is a critical need for contemporary education to address peritoneal surface malignancies (PSM). This study delineates the development of an online PSM curriculum for surgical trainees, in conjunction with a national consortium. Methods: A needs assessment survey was administered to attending surgical oncologists and trainees within the consortium, with a focus on current educational practices and preferences for PSM training. The identified focus areas informed the formulation of specific learning objectives and content. Results: The survey was completed by of 86/171 (48.5%) attending surgical oncologists in the group and 70 surgical trainees (56 residents and 14 fellows) from 31 unique institutions. Attending surgical oncologists emphasized trainee familiarity with general PSM principles and peritoneal metastases from lower gastrointestinal and gastric cancers when compared to gynecologic cancers and uncommon primaries (p < 0.001). Attending expectations increased incrementally with the trainee level in the knowledge and patient care domains. Attendings and trainees identified didactics and textbooks as primary modes of learning, although trainees reported using mobile learning tools more frequently. Disease site-specific educational content aligned with learning objectives was uploaded to a previously piloted online learning management system. Clinical management pathways and rotation guides were integrated to enhance the clinical applicability and consistency. Conclusions: Designing a PSM curriculum tailored to the educational needs of both attendants and trainees is feasible by using established pedagogical methods. This study provides a framework for teaching about complex diseases with limited educational literature.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis work was supported partially by the Teaching Innovation Project Grant awarded by Yale University Center for Teaching and Learning to VVB, FG, DS, and KKT.### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesI confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.YesData from this study may be made available upon reasonable request from qualified medical or scientific professionals, provided that the request aligns with the specified purpose and may involve de-identified individual participant data. Access to the requested data is granted after signing a data-access agreement.

PURPOSE:Immune checkpoint inhibitors have revolutionized the treatment of renal cell carcinoma (RCC), but many patients do not respond to therapy and the majority develop resistant disease over time. Thus, there is increasing need for alternative immunomodulating agents. The co-inhibitory molecule T-cell immunoglobulin and ITIM domain (TIGIT) may play a role in resistance to approved immune checkpoint inhibitors and is being investigated as a potential therapeutic target. The purpose of this study was to quantify TIGIT positivity in tumor-infiltrating T cells in RCC. METHODS:We employed tissue microarrays containing specimens from primary RCC tumors, adjacent normal renal tissue, and RCC metastases to quantify TIGIT within tumor-infiltrating CD3+ T cells using quantitative immunofluorescent analysis. We also compared these results to TIGIT+ CD3+ levels in four other tumor types (melanoma, non-small cell lung, cervical, and head and neck cancers). RESULTS:We did not observe significant differences in TIGIT positivity between primary RCC tumors and patient-matched metastatic samples. We found that the degree of TIGIT positivity in RCC is comparable to that in lung cancer but lower than that in melanoma, cervical, and head and neck cancers. Correlation analysis comparing TIGIT positivity to previously published, patient-matched spatial proteomic data by our group revealed a negative association between TIGIT and the checkpoint proteins PD-1 and LAG3. CONCLUSION:Our findings support careful evaluation of TIGIT expression on T cells in primary or metastatic RCC specimens for patients who may be treated with TIGIT-targeting antibodies, as increased TIGIT positivity might be associated with a greater likelihood of response to therapy.

Drugs or cellular products that bind to gp100 are being investigated for treatment of cutaneous melanoma. The relative specificity of gp100 expression in melanocytes makes it an attractive target to harness for therapeutic intent. For example, Tebentafusp, a bispecific gp100 peptide-HLA-directed CD3 T cell engager, has generated significant enthusiasm in recent years due to its success in improving outcomes for uveal melanoma and is being studied in cutaneous melanoma. However, the extent and intensity of gp100 expression in advanced cutaneous melanoma has not been well studied. Here, we interrogated a large cohort of primary and metastatic melanomas for gp100 expression by immunohistochemistry. Expression in metastatic samples was globally higher and almost uniformly positive, however the degree of intensity was variable. Using a quantitative immunofluorescence method, we confirmed the variability in expression. As gp100-binding drugs are assessed in clinical trials, the association between activity of the drugs and the level of gp100 expression should be studied in order to potentially improve patient selection.

The cytokine IL-18 has immunostimulatory effects but is negatively regulated by a secreted binding protein, IL-18BP, that limits IL-18's anticancer efficacy. A decoy-resistant form of IL-18 (DR-18) that avoids sequestration by IL-18BP while maintaining its immunostimulatory potential has recently been developed. Here, we investigated the therapeutic potential of DR-18 in renal cell carcinoma (RCC). Using pantumor transcriptomic data, we found that clear cell RCC had among the highest expression of IL-18 receptor subunits and IL18BP of tumor types in the database. In samples from patients with RCC treated with immune checkpoint inhibitors, IL-18BP protein expression increased in the tumor microenvironment and in circulation within plasma in nonresponding patients, and it decreased in the majority of responding patients. We used immunocompetent RCC murine models to assess the efficacy of DR-18 in combination with single- and dual-agent anti-PD-1 and anti-CTLA-4. In contrast to preclinical models of other tumor types, in RCC models, DR-18 enhanced the activity of anti-CTLA-4 but not anti-PD-1 treatment. This activity correlated with intratumoral enrichment and clonal expansion of effector CD8+ T cells, decreased Treg levels, and enrichment of proinflammatory antitumor myeloid cell populations. Our findings support further clinical investigation of the combination of DR-18 and anti-CTLA-4 in RCC.

Background Desmoplastic melanoma (DM) is a rare melanoma subtype characterized by dense fibrous stroma, a propensity for local recurrence, and a high response rate to programmed cell death protein 1 (PD-1) blockade. Occult sentinel lymph node positivity is significantly lower in both pure and mixed DM than in conventional melanoma, underscoring the need for better prognostic biomarkers to inform therapeutic strategies.Methods We assembled a tissue microarray comprising various cores of tumor, stroma, and lymphoid aggregates from 45 patients with histologically confirmed DM diagnosed between 1989 and 2018. Using a panel of 62 validated immune-oncology markers, we performed digital spatial profiling using the NanoString GeoMx platform and quantified expression in three tissue compartments defined by fluorescence colocalization (tumor (S100+/PMEL+/SYTO+), leukocytes (CD45+/SYTO+), and non-immune stroma (S100-/PMEL-/CD45-/SYTO+)).Results We observed higher expression of immune checkpoints (lymphocyte-activation gene 3 [LAG-3] and cytotoxic T-lymphocyte associated protein-4 [CTLA-4]) and cancer-associated fibroblast (CAF) markers (smooth muscle actin (SMA)) in the tumor compartments of pure DMs than mixed DMs. When comparing lymphoid aggregates (LA) to non-LA tumor cores, LAs were more enriched with CD20+B cells, but non-LA intratumoral leukocytes were more enriched with macrophage/monocytic markers (CD163, CD68, CD14) and had higher LAG-3 and CTLA-4 expression levels. Higher intratumoral PD-1 and LA-based LAG-3 expression appear to be associated with worse survival. CTLA-4) and cancer-associated fibroblast (CAF) markers (smooth muscle actin (SMA)) in the tumor compartments of pure DMs than mixed DMs. When comparing lymphoid aggregates (LA) to non-LA tumor cores, LAs were more enriched with CD20+B cells, but non-LA intratumoral leukocytes were more enriched with macrophage/monocytic markers (CD163, CD68, CD14) and had higher LAG-3 and CTLA-4 expression levels. Higher intratumoral PD-1 and LA-based LAG-3 expression appear to be associated with worse survival.Results We observed higher expression of immune checkpoints (lymphocyte-activation gene 3 [LAG-3] and cytotoxic T-lymphocyte associated protein-4 [CTLA-4]) and cancer-associated fibroblast (CAF) markers (smooth muscle actin (SMA)) in the tumor compartments of pure DMs than mixed DMs. When comparing lymphoid aggregates (LA) to non-LA tumor cores, LAs were more enriched with CD20+B cells, but non-LA intratumoral leukocytes were more enriched with macrophage/monocytic markers (CD163, CD68, CD14) and had higher LAG-3 and CTLA-4 expression levels. Higher intratumoral PD-1 and LA-based LAG-3 expression appear to be associated with worse survival. CTLA-4) and cancer-associated fibroblast (CAF) markers (smooth muscle actin (SMA)) in the tumor compartments of pure DMs than mixed DMs. When comparing lymphoid aggregates (LA) to non-LA tumor cores, LAs were more enriched with CD20+B cells, but non-LA intratumoral leukocytes were more enriched with macrophage/monocytic markers (CD163, CD68, CD14) and had higher LAG-3 and CTLA-4 expression levels. Higher intratumoral PD-1 and LA-based LAG-3 expression appear to be associated with worse survival.Conclusions Our proteomic analysis reveals an intra-tumoral population of SMA+CAFs enriched in pure DM. Additionally, increased expressions of immune checkpoints (LAG-3 and PD-1) in LA and within tumor were associated with poorer prognosis. These findings might have therapeutic implications and help guide treatment selection in addition to informing potential prognostic significance.

INTRODUCTION:Electronic consultations (e-consults) for periprocedural hematologic questions were introduced at the VA Connecticut Healthcare System in 2011. We sought to explore the relationship between the availability of e-consults, referral patterns, and surgical outcomes. METHODS:A single-center retrospective study of all perioperative hematologic consultations from 2006 to 2018 was conducted. Patient characteristics, indications, and outcomes were analyzed. Primary outcome measures were time from consult to surgery and operative morbidity via Clavien-Dindo classification. Secondary outcomes included consult volume and procedural outcomes of interest. RESULTS:Of 357 consultations, 62% were conducted via e-consults. 68.3% had associated procedural data and constituted the study cohort. Annual consult volume increased from 7 in 2006 to 41 in 2018, a 5.8-fold increase. E-consults comprised 20% of consults in 2011 but had risen to 92.3% in 2018. Time to resolution of e-consults after 2011 improved compared to pre-face-to-face (FTF-pre, P = 0.001) and FTF-post (P = 0.002). Time from consult to surgery remained unchanged. 8.4% had major complications (Clavien-Dindo >2) with readmission or reoperation occurring in 4.0% and 3.7%, respectively. Intraoperative and postoperative transfusions were required in 15.2% and 13.1% of cases, respectively. Hematologic complications (i.e., deep vein thrombosis/pulmonary embolism) occurred in 3.5%. Comparison between FTF and e-consults revealed no significant differences in these outcomes (P > 0.05, all). CONCLUSIONS:E-consults for perioperative hematologic issues were rapidly adopted and addressed more quickly than FTF consultation while time to surgery was unchanged despite increased consult volume. Adoption of the e-consult model was not associated with changes in the assessed operative outcomes.

In the last decade, immunotherapy has become the cornerstone in the management of patients with melanoma, the foremost cause of skin-cancer-related death in the USA. The emergence of immune checkpoint blockade as a crucial element in current immunotherapy and combination strategies has significantly transformed the treatments of resectable and advanced (unresectable or metastatic) melanoma. This paper reviews the landmark clinical trials that formed the basis of management of melanoma in the perioperative and metastatic setting. Furthermore, we discuss the rationale for the applications of PD-1 blockade and its combination with anti-CTLA-4 and anti-LAG-3. The review also explores new experimental combinations of PD-1 blockade with other immunomodulatory agents, including targeted therapies, anti-TIGIT antibodies, TLR-9 agonists, antiangiogenic agents, and mRNA vaccines.

© Annals of Translational Medicine. All rights reserved. Ann Transl Med 2023;11(10):370 | https://dx.doi.org/10.21037/atm-23-754 The CTLA-4 inhibitor ipilimumab is a vital component of the treatment armamentarium for patients with unresectable stage III/IV melanoma. Ipilimumab was Food and Drug Administration (FDA) approved in 2011 after demonstrating a survival benefit in advanced melanoma (1). The PD-1 inhibitor pembrolizumab subsequently prolonged overall survival (OS) compared to ipilimumab and was approved in 2014, as was nivolumab (2). Since then, PD-1 inhibitorbased therapies have persisted as the standard of care for advanced melanoma, often with the use of immune checkpoint inhibitor (ICI) doublets such as ipilimumab plus nivolumab, approved in 2015, or nivolumab plus the LAG3 inhibitor relatlimab, approved in 2022 (3,4). The success of ICI for patients with unresectable stage III/IV melanoma has led to investigation of these agents in earlier stages of disease, on the assumption of biological equivalence between residual microscopic versus macroscopic disease. In resected stage III melanoma, adjuvant ipilimumab was in i t ia l ly s tudied a t 10 mg/kg and improved recurrence-free survival (RFS) and OS compared to placebo (5). Subsequently, adjuvant PD-1 inhibition with pembrolizumab versus placebo (6), pembrolizumab versus interferon or ipilimumab (7), and nivolumab versus ipilimumab (8) improved RFS in resected stage III, IIIA(N2)-IV, and IIIB-IV melanoma, respectively. It is unknown whether the addition of adjuvant ipilimumab to nivolumab can improve outcomes in resected stage III/IV melanoma, however the benefit is clear in advanced melanoma. Ipilimumab 3 mg/kg plus nivolumab 1 mg/kg has numerically doubled OS compared to nivolumab monotherapy, as demonstrated in the 6.5 years follow-up of CheckMate-067 (3,9). Therefore, the purpose of CheckMate-915 by Weber et al. was to determine whether adjuvant ipilimumab plus nivolumab could improve RFS compared to adjuvant nivolumab monotherapy, which we review in this editorial. The study was entitled “Adjuvant Therapy of Nivolumab Combined With Ipilimumab Versus Nivolumab Alone in Patients With Resected Stage IIIB-D or Stage IV Melanoma” and was published in the Journal of Clinical Oncology in September 2022 (10). In CheckMate-915, there was no improvement in RFS for patients with resected stage IIIB-IV melanoma treated with combination therapy compared to adjuvant anti-PD-1 alone, the standard of care. Nor were there any differences in RFS for any of the examined subgroups, including stage. Twenty-four-month RFS was 64.6% in the combination group and 63.2% in the nivolumab group, which was unexpected given the superior activity of the combination in the metastatic setting (10). Importantly, the chosen ipilimumab dose in the trial was 1 mg/kg every 6 weeks. This dose and dosing interval has not been previously studied in melanoma and is a lower and less frequent dose than the standard 3 mg/kg administered every 3 weeks for up to 4 doses in advanced disease. The ipilimumab dosing Editorial Commentary

Melanocortin-1 receptor (MC1R) plays a critical role in human pigmentation and DNA repair mechanisms. MC1R-targeting agents are being investigated in clinical trials in melanoma patients, yet large studies investigating the rate and degree of MC1R expression in primary and metastatic human melanoma tissue are lacking. Using tissue microarrays containing three large cohorts of 225 cases of benign nevi, 189 with primary melanoma, and 271 with metastatic melanoma, we applied quantitative immunofluorescence and immunohistochemistry to comprehensively study MC1R protein expression. We show a stepwise elevation of MC1R expression in different stages of melanoma progression (nevi, primary, metastasis). Higher MC1R expression was seen in deeper (>1 mm) primary lesions, ulcerated lesions, and mucosal melanomas compared to cutaneous melanomas and was associated with shorter survival in primary and metastatic tumors. On multi-variable analysis, Breslow thickness, ulceration, male sex, and chronic sun exposure were independent predictors of worse overall survival in the primary melanoma cohort. In the metastatic melanoma cohort, MC1R expression and mucosal melanomas were independent predictors of inferior overall survival. Our data suggest that MC1R might be a valuable drug target in aggressive melanoma. Additional studies are warranted to determine its functional significance in melanoma progression and its utility as a predictive biomarker in patients receiving MC1R-directed therapies.

Background Desmoplastic melanoma (DM) is a rare melanoma subtype characterized by dense fibrous stroma and a propensity for local recurrence.1 2 Rates of occult sentinel lymph node positivity vary drastically between its two distinct histological subtypes, pure and mixed, presenting challenges in treatment and prognosis.3–5 A subset of activated cancer-associated fibroblasts (CAFs), characterized by alpha smooth muscle actin (SMA), has been associated with adverse prognosis in cancers with significant desmoplasia.6 Since DM has a high response rate to anti-PD-1 blockade,7 8 understanding the role of CAFs and lymphocytic aggregates (LA) in DM is crucial for informing therapeutic strategies and developing better prognostic biomarkers.6 9 10 Methods Tissue microarray slide was assembled, comprising 141 cores extracted from tissue sections of tumor, stroma, or LA. Samples were obtained from 45 patients with histologically confirmed DM, spanning a period from 1989 to 2018. High-plex proteomic analysis was performed using the Nanostring GeoMx platform with spatial resolution. Digital counts from a 68-plex panel of oligo-linked protein probes were quantified simultaneously in three tissue compartments defined by fluorescence colocalization [tumor (S100+/PMEL+), leukocytes (CD45+), and nonimmune stroma (S100-/PMEL-/CD45-/SYTO+)]. (figure 1a) Barcodes were normalized with internal spike-in controls to account for system variation. Results Of 45 patients with desmoplastic melanoma, 24% were female (11/45) and the median age was 74. 82% (37/45) had pure histology, 80% (36/45) originated in the head and neck region, 41% exhibited perineural invasion, and median Breslow's thickness was 4.9mm. 18% (8/45) received immunotherapy, 44% experienced recurrences, and 18% developed distant metastases. SMA+ CAFs were significantly enriched in the tumor compared to the stromal compartment (p=0.002), more prevalent in pure than mixed DM (p= 0.034) and associated with a worse overall survival (OS) on univariate Cox proportional hazards (p = 0.045) (figure 1b/1c). Compared to mixed DM, pure DM also expressed higher levels of intra-tumoral CD34+ (p=0.031) and fibronectin (p=0.001). When comparing LA to non-LA tumor cores, LA were more enriched with CD20+ B-cells (p=0.008), but non-LA tumor cores had higher LAG3 expression levels (p=0.014). High expressions of LAG-3 (p=0.028), CTLA-4 (p=0.033), and Ki-67 (p=0.026) within the leukocyte compartment were associated with worse OS on univariate analysis. Conclusions Our proteomic analysis revealed an intra-tumoral population of SMA+ CAFs enriched in pure DM. Differences between pure and mixed DM might have therapeutic implications and guide treatment selection in addition to informing potential prognostic significance. 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