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Unlimited replicative potential is one of the hallmarks of cancer cells. In melanoma, hTERT (telomerase reverse transcriptase) is frequently overexpressed because of activating mutations in its promoter, suggesting that telomerase is necessary for melanoma development. We observed, however, that a subset of melanoma metastases and derived cell lines had no telomere maintenance mechanism. Early passages of the latter displayed long telomeres that progressively shortened and fused before cell death. We propose that, during melanoma formation, oncogenic mutations occur in precursor melanocytes with long telomeres, providing cells with sufficient replicative potential, thereby bypassing the need to re-activate telomerase. Our data further support the emerging idea that long telomeres promote melanoma formation. These observations are important when considering anticancer therapies targeting telomerase., (Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Ipilimumab (Ipi) improves the survival of advanced melanoma patients with an incremental long-term benefit in 10-15 % of patients. A tumor signature that correlates with this survival benefit could help optimizing individualized treatment strategies., Methods: Freshly frozen melanoma metastases were collected from patients treated with either Ipi alone (n: 7) or Ipi combined with a dendritic cell vaccine (TriMixDC-MEL) (n: 11). Samples were profiled by immunohistochemistry (IHC), whole transcriptome (RNA-seq) and methyl-DNA sequencing (MBD-seq)., Results: Patients were divided in two groups according to clinical evolution: durable benefit (DB; 5 patients) and no clinical benefit (NB; 13 patients). 20 metastases were profiled by IHC and 12 were profiled by RNA- and MBD-seq. 325 genes were identified as differentially expressed between DB and NB. Many of these genes reflected a humoral and cellular immune response. MBD-seq revealed differences between DB and NB patients in the methylation of genes linked to nervous system development and neuron differentiation. DB tumors were more infiltrated by CD8(+) and PD-L1(+) cells than NB tumors. B cells (CD20(+)) and macrophages (CD163(+)) co-localized with T cells. Focal loss of HLA class I and TAP-1 expression was observed in several NB samples., Conclusion: Combined analyses of melanoma metastases with IHC, gene expression and methylation profiling can potentially identify durable responders to Ipi-based immunotherapy.

Purpose: Autologous monocyte-derived dendritic cells (DCs) electroporated with synthetic mRNA (TriMixDC-MEL) are immunogenic and have antitumor activity as a monotherapy in patients with pretreated advanced melanoma. Ipilimumab, an immunoglobulin G1 monoclonal antibody directed against the cytotoxic T-lymphocyte-associated protein 4 receptor that counteracts physiologic suppression of T-cell function, improves the overall survival of patients with advanced melanoma. This phase II study investigated the combination of TriMixDC-MEL and ipilimumab in patients with pretreated advanced melanoma., Patients and Methods: Thirty-nine patients were treated with TriMixDC-MEL (4 × 10(6) cells administered intradermally and 20 × 10(6) cells administered intravenously) plus ipilimumab (10 mg/kg every 3 weeks for a total of four administrations, followed by maintenance therapy every 12 weeks in patients who remained progression free). Six-month disease control rate according to the immune-related response criteria served as the primary end point., Results: The 6-month disease control rate was 51% (95% CI, 36% to 67%), and the overall tumor response rate was 38% (including eight complete and seven partial responses). Seven complete responses and one partial tumor response are ongoing after a median follow-up time of 36 months (range, 22 to 43 months). The most common treatment-related adverse events (all grades) consisted of local DC injection site skin reactions (100%), transient post-DC infusion chills (38%) and flu-like symptoms (84%), dermatitis (64%), hepatitis (13%), hypophysitis (15%), and diarrhea/colitis (15%). Grade 3 or 4 immune-related adverse events occurred in 36% of patients. There was no grade 5 adverse event., Conclusion: The combination of TriMixDC-MEL and ipilimumab is tolerable and results in an encouraging rate of highly durable tumor responses in patients with pretreated advanced melanoma., (© 2016 by American Society of Clinical Oncology.)

Melanoma is not only one of the most immunogenic cancers but also one of the most effective cancers at subverting host immunity. The role of T lymphocytes in tumor immunity has been extensively studied in melanoma, whereas less is known about the importance of B lymphocytes. The effects of plasma cells (PCs), in particular, are still obscure. The aim of this study was to characterize pathological features and clinical outcome of primary cutaneous melanomas associated with PCs. Moreover, we investigated the origins of the melanoma-associated PCs. Finally, we studied the outcome of patients with primary melanomas with PCs. We reviewed 710 melanomas to correlate the presence of PCs with histological prognostic markers. Immunohistochemistry for CD138 and heavy and light chains was performed in primary melanomas (PM) and in loco-regional lymph nodes (LN), both metastatic and not metastatic. In three PM and nine LN with frozen material, VDJ-rearrangement was analyzed by Gene Scan Analysis. Survival analysis was performed on a group of 85 primary melanomas >2 mm in thickness. Forty-one cases (3.7%) showed clusters/sheets of PCs. PC-rich melanomas occurred at an older age and were thicker, more often ulcerated and more mitotically active (P<0.05). PCs were polyclonal and often expressed IgA in addition to IgG. In LN, clusters/sheets of IgA+ PCs were found both in the sinuses and subcapsular areas. Analysis of VDJ-rearrangements showed the IgA to be oligoclonal. Melanomas with clusters/sheets of PCs had a significantly worse survival compared with melanomas without PCs while, interestingly, melanomas with sparse PCs were associated with a better clinical outcome (P=0.002). In conclusion, melanomas with sheets/clusters of PCs are associated with worse prognosis. IgG and IgA are the isotypes predominantly produced by these PCs. IgA oligoclonality suggests an antigen-driven response that facilitates melanoma progression by a hitherto unknown mechanism.

BRAF inhibitors elicit rapid antitumor responses in the majority of patients with BRAF(V600)-mutant melanoma, but acquired drug resistance is almost universal. We sought to identify the core resistance pathways and the extent of tumor heterogeneity during disease progression. We show that mitogen-activated protein kinase reactivation mechanisms were detected among 70% of disease-progressive tissues, with RAS mutations, mutant BRAF amplification, and alternative splicing being most common. We also detected PI3K-PTEN-AKT-upregulating genetic alterations among 22% of progressive melanomas. Distinct molecular lesions in both core drug escape pathways were commonly detected concurrently in the same tumor or among multiple tumors from the same patient. Beyond harboring extensively heterogeneous resistance mechanisms, melanoma regrowth emerging from BRAF inhibitor selection displayed branched evolution marked by altered mutational spectra/signatures and increased fitness. Thus, melanoma genomic heterogeneity contributes significantly to BRAF inhibitor treatment failure, implying upfront, cotargeting of two core pathways as an essential strategy for durable responses.

A large body of evidence supports the idea that the tumor environment is immunosuppressive, notably for T lymphocytes. Yet, in some tumor types, the presence of tumor-infiltrating T cells has favorable prognostic value. In order to better understand the functional value of T cells in human tumors, we focused on cutaneous metastases of melanoma and observed that some of them host ectopic lymphoid structures in which B cell, and possibly T cell, responses take place. This observation is discussed in the context of current views on immunosuppression in tumors., (© 2013 New York Academy of Sciences.)

Lymphoid neogenesis, or the development of lymphoid structures in nonlymphoid organs, is frequently observed in chronically inflamed tissues, during the course of autoimmune, infectious, and chronic graft rejection diseases, in which a sustained lymphocyte activation occurs in the presence of persistent antigenic stimuli. The presence of such ectopic lymphoid structures has also been reported in primary lung, breast, and germline cancers, but not yet in melanoma. In this study, we observed ectopic lymphoid structures, defined as lymphoid follicles comprising clusters of B lymphocytes and follicular dendritic cells (DC), associated with high endothelial venules (HEV) and clusters of T cells and mature DCs, in 7 of 29 cutaneous metastases from melanoma patients. Some follicles contained germinal centers. In contrast to metastatic lesions, primary melanomas did not host follicles, but many contained HEVs, suggesting an incomplete lymphoid neogenesis. Analysis of the repertoire of rearranged immunoglobulin genes in the B cells of microdissected follicles revealed clonal amplification, somatic mutation and isotype switching, indicating a local antigen-driven B-cell response. Surprisingly, IgA responses were observed despite the nonmucosal location of the follicles. Taken together, our findings show the existence of lymphoid neogenesis in melanoma and suggest that the presence of functional ectopic lymphoid structures in direct contact with the tumor makes the local development of antimelanoma B- and T-cell responses possible., (©2012 AACR.)

Tumor-infiltrating T lymphocytes (TILs) are observed in a number of human primary or metastatic tumors. Recently, gene expression profiling experiments suggested that the presence of T cells in metastatic melanomas before vaccinating the patients with tumor antigens could be a biomarker for clinical benefit from the vaccines. In this context, we review results pertaining to TILs in human melanomas, their prognostic value, and some possible reasons why their presence could help in selecting melanoma patients for vaccination against tumor-specific antigens.

A core challenge in cancer immunotherapy is to understand the basis for efficacious vaccine responses in human patients. In previous work we identified a melanoma patient who displayed a low-level antivaccine cytolytic T-cell (CTL) response in blood with tumor regression after vaccination with melanoma antigens (MAGE). Using a genetic approach including T-cell receptor β (TCRβ) cDNA libraries, we found very few antivaccine CTLs in regressing metastases. However, a far greater number of TCRβ sequences were found with several of these corresponding to CTL clones specific for nonvaccine tumor antigens, suggesting that antigen spreading was occurring in regressing metastases. In this study, we found another TCR belonging to tumor-specific CTL enriched in regressing metastases and detectable in blood only after vaccination. We used the TCRβ sequence to detect and clone the desired T cells from tumor-infiltrating lymphocytes isolated from the patient. This CD8 clone specifically lysed autologous melanoma cells and displayed HLA-A2 restriction. Its target antigen was identified as the mitochondrial enzyme caseinolytic protease. The target antigen gene was mutated in the tumor, resulting in production of a neoantigen. Melanoma cell lysis by the CTL was increased by IFN-γ treatment due to preferential processing of the antigenic peptide by the immunoproteasome. These results argue that tumor rejection effectors in the patient were indeed CTL responding to nonvaccine tumor-specific antigens, further supporting our hypothesis. Among such antigens, the mutated antigen we found is the only antigen against which no T cells could be detected before vaccination. We propose that antigen spreading of an antitumor T-cell response to truly tumor-specific antigens contributes decisively to tumor regression., (©2011 AACR.)