After local treatment of one to three melanoma brain metastases, adjuvant WBRT does not provide clinical benefit in terms of distant intracranial control, survival, or preservation of performance status.

Our findings are the first to suggest that tumor CD155 supports an increase in the fraction of PD1⁺CD8⁺ T cells in anti-PD1 refractory melanoma tumors and, further, that targeting the CD155 pathway might improve response to anti-PD1 therapy for patients with metastatic melanoma.

Das Wissen über die genetischen Treiber und therapeutischen Zielstrukturen von Melanomen der Schleimhäute ist bisher lückenhaft, weil nur wenig umfassende Daten zu den Mutationen bei dieser seltenen Tumorart vorliegen. Um die genomische Landschaft des mukosalen Melanoms besser zu verstehen, beschreiben wir hier die Analyse von 67 Tumoren mittels Whole-Genome-Sequenzierung nebst Validierung von Treibermutationen durch Whole-Exome-Sequenzierung von 45 Tumoren. Die Tumoren zeigten eine geringe Punktmutationslast und eine hohe Zahl von Strukturvarianten, einschließlich rekurrenter Rearrangements im Bereich von <i>TERT</i>, <i>CDK4</i> und <i>MDM2</i>. Signifikant mutierte Gene sind <i>NRAS, BRAF, NF1, KIT, SF3B1, TP53, SPRED1, ATRX, HLA-A</i> und <i>CHD8</i>. <i>SF3B1</i>-Mutationen kamen mit erhöhter Häufigkeit in Melanomen des weiblichen Genitaltrakts und der Anorektalregion vor, und <i>CTNNB1</i>-Mutationen deuten auf den Beitrag einer gestörten WNT-Signaltransduktion zur Entstehung eines Teils der Schleimhautmelanome hin. <i>TERT</i>-Aberrationen und <i>ATRX</i>-Mutationen sind mit Veränderungen der Telomerlängen assoziiert. Die Mutationsprofile eines Großteils der Schleimhautmelanome deuten auf eine mögliche Empfindlichkeit gegenüber CDK4/6- und/oder MEK-Inhibitoren hin.

Abstract Background: The prognosis of patients with early-stage melanoma remains poor with overall survival at 10 years below 40% in patients with stage IIC disease. The use of anti-PD-1 adjuvant therapy has improved outcomes for some, but the role of the immune system in early disease and selection of ideal candidates for checkpoint blockade require further elucidation. Clonality of the tumor T-cell repertoire, as measured by next-generation immunosequencing of T-cell receptors (TCRs), recently demonstrated its utility as a biomarker of response to anti-PD-1 therapy in metastatic melanoma. Here, we aim to evaluate its ability to predict recurrence in patients who underwent resection of primary melanomas. Methods: Biomarkers of progression free survival (PFS) were evaluated in a cohort of 72 archival FFPE tumors from subjects who were followed for a minimum of five years. Tumor TCR-beta clonality and infiltrating T-cell fraction (fraction of nucleated cells that are T-cells) were quantified by the immunoSEQ® Assay (Adaptive Biotechnologies) while Breslow thickness, ulceration, mitotic rate, and briskness of tumor infiltrating lymphocytes were assessed by histopathology. Results: T-cell fraction, but not clonality, was a robust independent variable in predicting PFS (Cox Proportional Hazard Ratio = 0.71, p-value = 0.007) after resection of primary melanomas in patients who were not treated with immunotherapy regimens. In a gradient boosted model, T-cell fraction was second only to Breslow thickness in weighted importance for predicting PFS, which together accounted for 60% of the model's classification power. Variables comprising the remaining 40% included ulceration, patient age, tumor stage, and mitotic rate, and, except for stage, generally correlated with Breslow thickness. T-cell fraction, however, was not correlated with any clinical or histopathological variable, including briskness. The bivariate model Cox Regression of Breslow thickness and T-cell fraction performed better than Breslow thickness alone in predicting PFS (Likelihood Ratio Test p-value = 0.03). Furthermore, patients with high T-cell fractions had delayed recurrence (median of 19 vs 9 months, high vs low T-cell fraction in melanomas > 2.5mm; median PFS not reached for melanomas < 2.5mm). Conclusion: Patients with high T-cell fractions in intermediate and high-thickness melanomas have a more favorable prognosis and may be ideal candidates for adjuvant immunotherapy to prolong PFS. These findings are currently being validated in an expanded cohort of archival samples. Disclaimers/disclosures: For Research Use Only. Not for use in diagnostic procedures. Partial financial support provided by Adaptive Biotechnologies. Citation Format: Julie A. Rytlewski, Wiebke Pruessmann, James Wilmott, Martin C. Mihm, Beatrice Dyring-Andersen, Rachael A. Clark, Erik Yusko, Alexandra Snyder, Harlan Robins, Richard Scolyer, Thomas S. Kupper. T cell receptor immunosequencing improves prediction of melanoma recurrence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-146.

Little is known about the risk of progression of lentigo maligna to lentigo maligna melanoma. We determine the annual risk of progression of lentigo maligna to lentigo maligna melanoma by analysing a prospective population-based survey of recently diagnosed anterior (visible in a mirror) head and neck lentigo malignas and lentigo maligna melanomas. Six hundred eighty-two consecutive patients aged 18-80 years with non-recurrent lentigo maligna or lentigo maligna melanoma, diagnosed between 1 July 2015 and 20 April 2016, were identified from pathology notifications to the New South Wales Cancer Registry (Australia) and sent survey questionnaires soon after diagnosis (median 4.6 months interquartile range: 3.8-5.7). Details of the time the lesion was present and when changes to it were noticed before diagnostic biopsy were ascertained by surveying the patients, of whom 53.5% agreed to participate. There was little difference between the proportions of lentigo maligna melanoma and lentigo maligna in the consenting and non-consenting patients (P = 0.56). Two hundred twenty-eight lentigo maligna (median age 67 years, range: 38-80) and 33 lentigo maligna melanoma (70 years, 43-80) were surveyed. There was no difference between the time lentigo maligna melanoma was present on the skin (median 18 months, range: 0-690) and the time lentigo maligna was (18 months, 0-665) (P = 0.972). The estimated risk of progression of lentigo maligna to lentigo maligna melanoma was 3.5% per year (95% confidence interval: 2.5-5.0). This equates to an average time for lentigo maligna to progress to lentigo maligna melanoma of 28.3 years (95% confidence interval: 20.0-40.5) in this population. Although our data suggests that the annual progression rate of lentigo maligna is more than 25 times greater than previously suggested, the rate is still low.

Glioblastoma, the most aggressive form of glioma, has a 5-year survival rate of <5%. While radiation and immunotherapies are routinely studied in the murine Gl261 glioma model, little is known about its inherent immune response. This study quantifies the temporal and spatial localization of immune cell populations and mediators during glioma development. Eight-week old male C57Bl/6 mice were orthotopically inoculated with 1x106 Gl261 cells and tumor morphology, local and systemic immune cell populations, and plasma cytokines/chemokines assessed at day 0, 1, 3, 7, 14, and 21 post-inoculation by magnetic resonance imaging, chromogenic immunohistochemistry, multiplex immunofluorescent immunohistochemistry, flow cytometry and multiplex immunoassay respectively. From day 3 tumors were distinguishable with >30% Ki67 and increased tissue vascularization (p<0.05). Increasing tumor proliferation/malignancy and vascularization were associated with significant temporal changes in immune cell populations within the tumor (p<0.05) and systemic compartments (p = 0.02 to p<0.0001). Of note, at day 14 16/24 plasma cytokine/chemokines levels decreased coinciding with an increase in tumor cytotoxic T cells, natural killer and natural killer/T cells. Data derived provide baseline characterization of the local and systemic immune response during glioma development. They reveal that type II macrophages and myeloid-derived suppressor cells are more prevalent in tumors than regulatory T cells, highlighting these cell types for further therapeutic exploration.

The results demonstrate that ctDNA profiles can accurately differentiate pseudoprogression from true progression of disease in patients with melanoma treated with PD-1 antibodies. Results of this blood test performed at regular intervals during systemic treatment reflect tumor biology and have potential as a powerful biomarker to predict long-term response and survival.

TPS9605 Background: Adjuvant (adj) immune checkpoint inhibition (ICI) improves relapse free survival (RFS) in stage III melanoma patients (pts). However, preclinical and translational data suggest that neo-adjuvant (neoadj) treatment might be favorable due to broader immune activation. The phase 1b OpACIN study comparing neoadj to adj IPI plus NIVO demonstrated a high pathological response rate (pRR) of 78% complicated by 90% gr 3-4 immune-related adverse events (irAEs). The phase 2 OpACIN-neo trial tested safety and efficacy of three different schemes of neoadj IPI+NIVO and identified two cycles of IPI 1mg/kg + NIVO 3mg/kg as well tolerated (20% gr 3-4 irAEs), with a high pRR of 77%. In both trials, none of the pts with a pathologic response have relapsed after a median follow-up of 30 and 8.3 months. In stage IV melanoma, long-term benefit is observed in patients achieving CR with ICI, even after cessation of therapy. This raises the question of whether a therapeutic lymph node dissection (TLND) can be omitted when a deep pathologic response with neoadj IPI+NIVO is achieved. Methods: The aim of this international multi-center investigator-initiated phase 2 PRADO extension study is to confirm the pRR and toxicity of 2 cycles of neoadjuvant IPI 1mg/kg + NIVO 3mg/kg (the preferred OPACIN-neo regimen) and to test response-driven subsequent therapy i.e. omitting surgery and adjuvant ICI based on the pathological response. 100-110 pts with stage IIIB/C melanoma and a measurable lymph node (≥15mm according to RECIST 1.1) will receive two cycles of IPI 1mg/kg + NIVO 3mg/kg after marker placement into the largest lymph node metastasis. After six weeks, pts will undergo resection of the index lymph node. For pCR/near pCR, pts will not undergo TLND; For pPR, pts will undergo TLND; and for pNR, pts will undergo TLND and start adjuvant NIVO or targeted therapy +/- radiotherapy for 52 weeks. Primary endpoints are pRR of marked lymph node and RFS at 24 months. Baseline biopsies, blood samples (week 0, 6, 12) and faeces (week 0, 6) will be collected for translational research analyses. The first patient in this trial was included in October 2018; 22 patients have been enrolled. Clinical trial information: NCT02977052.

Brain metastases are a major cause of melanoma-related mortality and morbidity. We undertook whole-exome sequencing of 50 tumours from patients undergoing surgical resection of brain metastases presenting as the first site of visceral disease spread and validated our findings in an independent dataset of 18 patients. Brain metastases had a similar driver mutational landscape to cutaneous melanomas in TCGA. However, KRAS was the most significantly enriched driver gene, with 4/50 (8%) of brain metastases harbouring non-synonymous mutations. Hotspot KRAS mutations were mutually exclusive from BRAF^V600, NRAS and HRAS mutations and were associated with a reduced overall survival from the resection of brain metastases (HR 10.01, p = 0.001). Mutations in KRAS were clonal and concordant with extracranial disease, suggesting that these mutations are likely present within the primary. Our analyses suggest that KRAS mutations could help identify patients with primary melanoma at higher risk of brain metastases who may benefit from more intensive, protracted surveillance.

The results of the current study demonstrated the comparable prognostic impact of mitotic rate and ulceration, providing support for its reincorporation into the T category.