Purpose: To evaluate the effects of BRAF inhibition on the tumor microenvironment in patients with metastatic melanoma.Experimental Design: Thirty-five biopsies were collected from 16 patients with metastatic melanoma pretreatment (day 0) and at 10 to 14 days after initiation of treatment with either BRAF inhibitor alone (vemurafenib) or BRAF þ MEK inhibition (dabrafenib þ trametinib) and were also taken at time of progression. Biopsies were analyzed for melanoma antigens, T-cell markers, and immunomodulatory cytokines.Results: Treatment with either BRAF inhibitor alone or BRAF þ MEK inhibitor was associated with an increased expression of melanoma antigens and an increase in CD8þ T-cell infiltrate. This was also associated with a decrease in immunosuppressive cytokines [interleukin (IL)-6 and IL-8] and an increase in markers of T-cell cytotoxicity. Interestingly, expression of exhaustion markers TIM-3 and PD1 and the immunosuppressive ligand PDL1 was increased on treatment. A decrease in melanoma antigen expression and CD8 T-cell infiltrate was noted at time of progression on BRAF inhibitor alone and was reversed with combined BRAF and MEK inhibition.Conclusions: Together, these data suggest that treatment with BRAF inhibition enhances melanoma antigen expression and facilitates T-cell cytotoxicity and a more favorable tumor microenvironment, providing support for potential synergy of BRAF-targeted therapy and immunotherapy. Interestingly, markers of T-cell exhaustion and the immunosuppressive ligand PDL1 are also increased with BRAF inhibition, further implying that immune checkpoint blockade may be critical in augmenting responses to BRAF-targeted therapy in patients with melanoma.

SUMMARY DNA methylation at the 5-position of cytosine (5-mC) is a key epigenetic mark critical for various biological and pathological processes. 5-mC can be converted to 5-hydroxymethylcytosine (5-hmC) by the Ten-Eleven Translocation (TET) family of DNA hydroxylases. Here we report that “loss of 5-hmC” is an epigenetic hallmark of melanoma with diagnostic and prognostic implications. Genome-wide mapping of 5-hmC reveals loss of 5-hmC landscape in the melanoma epigenome. We show that down-regulation of Isocitrate Dehydrogenase 2 (IDH2) and TET family enzymes is likely one of the mechanisms underlying 5-hmC loss in melanoma. Rebuilding the 5-hmC landscape in melanoma cells by reintroducing active TET2 or IDH2 suppresses melanoma growth and increases tumor-free survival in animal models. Thus, our study reveals a critical function of 5-hmC in melanoma development and directly links the IDH and TET activity-dependent epigenetic pathway to 5-hmC-mediated suppression of melanoma progression, suggesting a new strategy for epigenetic cancer therapy.

PRAME (PReferentially expressed Antigen in MElanoma) is a melanoma-associated antigen that was isolated by autologous T cells in a melanoma patient. While frequent PRAME mRNA expression is well documented in cutaneous and ocular melanomas, little is known about PRAME protein expression in melanocytic tumors. In this study we examined the immunohistochemical expression of PRAME in 400 melanocytic tumors, including 155 primary and 100 metastatic melanomas, and 145 melanocytic nevi. Diffuse nuclear immunoreactivity for PRAME was found in 87% of metastatic and 83.2% of primary melanomas. Among melanoma subtypes, PRAME was diffusely expressed in 94.4% of acral melanomas, 92.5% of superficial spreading melanomas, 90% of nodular melanomas, 88.6% of lentigo maligna melanomas, and 35% of desmoplastic melanomas. When in situ and nondesmoplastic invasive melanoma components were present, PRAME expression was seen in both. Of the 140 cutaneous melanocytic nevi, 86.4% were completely negative for PRAME. Immunoreactivity for PRAME was seen, albeit usually only in a minor subpopulation of lesional melanocytes, in 13.6% of cutaneous nevi, including dysplastic nevi, common acquired nevi, traumatized/recurrent nevi, and Spitz nevi. Rare isolated junctional melanocytes with immunoreactivity for PRAME were also seen in solar lentigines and benign nonlesional skin. Our results suggest that immunohistochemical analysis for PRAME expression may be useful for diagnostic purposes to support a suspected diagnosis of melanoma. It may also be valuable for margin assessment of a known PRAME-positive melanoma, but its expression in nevi, solar lentigines, and benign nonlesional skin can represent a pitfall and merits further investigations to better assess the potential clinical utility of this marker.

Ipilimumab improves survival in advanced melanoma and can induce immune-mediated tumor vasculopathy. Besides promoting angiogenesis, vascular endothelial growth factor (VEGF) suppresses dendritic cell maturation and modulates lymphocyte endothelial trafficking. This study investigated the combination of CTLA-4 blockade with ipilimumab and VEGF inhibition with bevacizumab. Patients with metastatic melanoma were treated in four dosing cohorts of ipilimumab (3 or 10 mg/kg) four doses at 3-week intervals and then every 12 weeks, and bevacizumab (7.5 or 15 mg/kg) every 3 weeks. Forty-six patients were treated. Inflammatory events included giant cell arteritis (1), hepatitis (2), and uveitis (2). On-treatment tumor biopsies revealed activated vessel endothelium with extensive CD8+ and macrophage cell infiltration. Peripheral blood analyses demonstrated increases in CCR7+/−/CD45RO+ cells and anti-galectin antibodies. Best overall response included 8 partial responses, 22 stable disease, and a disease-control rate (DCR) of 67.4%. Median survival was 25.1 months. Bevacizumab influences changes in tumor vasculature and immune responses with ipilimumab administration. The combination of bevacizumab and ipilimumab can be safely administered and reveals VEGF-A blockade influences on inflammation, lymphocyte trafficking, and immune regulation. This provides a basis for further investigating the dual roles of angiogenic factors in blood vessel formation and immune regulation as well as future combinations of anti-angiogenesis agents and immune checkpoint blockade.

PRAME (PReferentially expressed Antigen in MElanoma) is a melanoma-associated antigen. Although diffuse immunoreactivity for PRAME is found in most primary cutaneous melanomas, melanocytic nevi express PRAME usually only in a subpopulation of tumor cells or not at all. Hence, testing for PRAME expression has the potential to provide useful information for the assessment for diagnostically ambiguous melanocytic neoplasms. Many of the latter tumors are currently studied by cytogenetic methods for ancillary evidence in support of or against a diagnosis of melanoma. In this study we analyzed 110 diagnostically problematic melanocytic tumors comparing results for PRAME immunohistochemistry (IHC) with those from fluorescence in situ hybridization and/or single nucleotide polymorphism-array, and each with the final diagnostic interpretation. In 90% of cases there was concordance between PRAME IHC and cytogenetic tests results, and in 92.7% concordance between PRAME IHC and the final diagnosis. The high concordance between PRAME IHC and cytogenetic test results as well as the final diagnosis supports the use of PRAME IHC as an ancillary test in the evaluation of ambiguous primary cutaneous melanocytic neoplasms, especially given its practical advantage of lower cost and faster turnaround over cytogenetic or gene expression studies. However, our results indicate that PRAME IHC and cytogenetic tests for melanocytic tumors are not entirely interchangeable and on occasion each type of test may yield false-negative or false-positive results.

The distinction of metastatic melanoma from melanocytic nevi in lymph nodes can on occasion be difficult. As diffuse immunohistochemical (IHC) PRAME (PReferentially expressed Antigen in MElanoma) expression is detected in the majority of primary and metastatic melanomas, but rarely in nevi, we reasoned that PRAME could be a useful adjunct marker for the diagnosis of melanocytes in lymph nodes. In this study, we examined 45 nodal melanocytic deposits comprising 30 nodal nevi and 15 melanoma metastases. The latter were diagnostically not straightforward because they either coexisted with nodal nevi or were present in perinodal fibrous tissue. All nodal nevi (30/30) were negative for PRAME, whereas all melanoma metastases (15/15) were diffusely positive for PRAME IHC. We additionally report the novel use of a PRAME/Melan A dual-label immunostain. Our results show that PRAME IHC may be useful in the assessment of diagnostically challenging nodal melanocytic deposits, such as intraparenchymal nodal nevi, metastases confined to the capsular fibrous tissue, or in the setting of small metastases coexisting with a nodal nevus in the same lymph node.

SUMMARY Atg16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with inflammatory bowel disease. Here we find that Atg16L1 deficiency leads to an exacerbated graft-versus-host disease (GVHD) in a mouse model of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Atg16L1-deficient allo-HSCT recipients with GVHD displayed increased T cell proliferation due to increased dendritic cell (DC) numbers and co-stimulatory molecule expression. Reduced autophagy within DCs was associated with lysosomal abnormalities and decreased amounts of A20, a negative regulator of DC activation. These results broaden the function of Atg16L1 and the autophagy pathway to include a role in limiting a DC-mediated response during inflammatory disease, such as GVHD.

Human papillomavirus (HPV) has been reported in 12-82% of penile squamous cell carcinomas (SCC). There is an association of the virus with basaloid and warty carcinomas but the reported prevalence is variable. The causes of these variations are not clear. They may be owing to geographic differences, the use of different techniques to detect HPV, the status of the original paraffin blocks, or to variable criteria in tumor classification. The aims of the study were to determine the prevalence of HPV in penile SCC and subtypes using a sensitive technique, to investigate genotypes involved, and to search for other morphologic features associated with the virus from a series of cases from Paraguay. HPV detection was done by SPF-10 polymerase chain reaction followed by DNA enzyme-immunoassay and genotyping by LIPA 25 (version 1). Samples were tested at Catalan Institute of Oncology, Barcelona, and cross testing was carried out at the Delft Diagnostic Laboratories in The Netherlands. HPV was detected in 64 of 202 cases (32%). Thirteen tumors had multiple HPV genotypes. Most prevalent genotypes were HPV-16 (46 cases), HPV-6 (6 cases), and HPV-18 (4 cases), either in single or in multiple infections. HPV was preferentially associated with warty-basaloid (82%), basaloid (76%), and warty (39%) carcinomas and not detected in verrucous, mixed verrucous-papillary, pseudohyperplastic, and pseudoglandular SCCs. There was a strong association between HPV and higher histologic grade. Basaloid cells were more frequently found in HPV positive tumors (72%) and this association was statistically significant in univariate and multivariate analyses. Cells with koilocytotic features and keratinizing squamous cells were also present but to a much lesser degree (47% and 19%, respectively). In summary, HPV was found in a third of the cases and the most common genotype was HPV-16. Low-risk genotypes were rarely found in single infections, representing 4 cases among all analyzed (2%). There was an association between HPV presence and higher histologic grade and with basaloid, warty-basaloid, and warty carcinomas. Our results also suggest that, in penile SCC, the basaloid cell is the best tissue marker for oncogenic HPV infection.