Immunotherapy for the management of advanced melanoma: the next steps

microRNA expression patterns in tumor infiltrating lymphocytes are strongly associated with response to adoptive cell transfer therapy

Adoptive cell transfer (ACT) using autologous tumor infiltrating lymphocytes (TILs) was previously shown to yield clinical response in metastatic melanoma patients as an advanced line. Unfortunately, there is no reliable marker for predicting who will benefit from the treatment. We analyzed TIL samples from the infusion bags used for treatment of 57 metastatic melanoma patients and compared their microRNA profiles. The discovery cohort included six responding patients and seven patients with progressive disease, as defined by RECIST1.1. High throughput analysis with NanoString nCounter demonstrated significantly higher levels of miR-34a-5p and miR-22-3p among TIL from non-responders. These results were validated in TIL infusion bag samples from an independent cohort of 44 patients, using qRT-PCR of the individual microRNAs. Using classification trees, a data-driven predictive model for response was built, based on the level of expression of these microRNAs. Patients that achieved stable disease were classified with responders, setting apart the patients with progressive disease. Moreover, the expression levels of miR-34a-5p in the infused TIL created distinct survival groups, which strongly supports its role as a potential biomarker for TIL-ACT therapy. Indeed, when tested against autologous melanoma cells, miR^Low TIL cultures exhibited significantly higher cytotoxic activity than miR^High TIL cultures, and expressed features of terminally exhausted effectors. Finally, overexpression of miR-34a-5p or miR-22-3p in TIL inhibited their cytotoxic ability in vitro. Overall, we show that a two-microRNA signature correlates with failure of TIL-ACT therapy and survival in melanoma patients.

Development of an immune-related gene pairs index for the prognosis analysis of metastatic melanoma

Melanoma is a skin cancer with great metastatic potential, which is responsible for the major deaths in skin cancer. Although the prognosis of melanoma patients has been improved with the comprehensive treatment, for patients with metastasis, the complexity and heterogeneity of diffuse diseases make prognosis prediction and systematic treatment difficult and ineffective. Therefore, we established a novel personalized immune-related gene pairs index (IRGPI) to predict the prognosis of patients with metastatic melanoma, which was conducive to provide new insights into clinical decision-making and prognostic monitoring for metastatic melanoma. Through complex analysis and filtering, we identified 24 immune-related gene pairs to build the model and obtained the optimal cut-off value from receiver operating characteristic curves, which divided the patients into high and low immune-risk groups. Meantime, the Kaplan–Meier analysis, Cox regression analysis and subgroup analysis showed that IRGPI had excellent prognostic value. Furthermore, IRGPI was shown that was closely associated with immune system in the subsequent tumor microenvironment analysis and gene set enrichment analysis. In addition, we broken through the data processing limitations of traditional researches in different platforms through the application of gene pairs, which would provide great credibility for our model. We believe that our research would provide a new perspective for clinical decision-making and prognostic monitoring in metastatic melanoma.

Complex Formation with Monomeric α-Tubulin and Importin 13 Fosters c-Jun Protein Stability and Is Required for c-Jun's Nuclear Translocation and Activity

Microtubules are highly dynamic structures, which consist of α- and β-tubulin heterodimers. They are essential for a number of cellular processes, including intracellular trafficking and mitosis. Tubulin-binding chemotherapeutics are used to treat different types of tumors, including malignant melanoma. The transcription factor c-Jun is a central driver of melanoma development and progression. Here, we identify the microtubule network as a main regulator of c-Jun activity. Monomeric α-tubulin fosters c-Jun protein stability by protein-protein interaction. In addition, this complex formation is necessary for c-Jun's nuclear localization sequence binding to importin 13, and consequent nuclear import and activity of c-Jun. A reduction in monomeric α-tubulin levels by treatment with the chemotherapeutic paclitaxel resulted in a decline in the nuclear accumulation of c-Jun in melanoma cells in an experimental murine model and in patients' tissues. These findings add important knowledge to the mechanism of the action of microtubule-targeting drugs and indicate the newly discovered regulation of c-Jun by the microtubule cytoskeleton as a novel therapeutic target for melanoma and potentially also other types of cancer.

The Tumor-Promoting Role of TRIP4 in Melanoma Progression and its Involvement in Response to BRAF-Targeted Therapy

TRIP4 was identified as having a proliferation promoting effect in melanoma cells based on small interfering RNA library screening, however, its precise function in melanoma progression is completely unknown. Here, we explored the carcinogenic role of TRIP4 in melanoma. The high expression of TRIP4 was observed in human melanoma cells and tissues. Its knockdown suppressed melanoma progression in vitro and in vivo, including melanoma cell proliferation, migration, and invasion inhibition and apoptosis induction. Further mechanistic analysis showed that TRIP4 promoted melanoma growth through modulation of COX-2 and iNOS expression partially by activating NF-κB signaling indirectly and partially by the direct anchoring of itself at COX-2 and iNOS promoter via synergy with p300. TRIP4 was confirmed to regulate the sensitivity to anti-BRAF targeted agents in BRAF-mutant human melanoma cells and xenografts. In addition, clinical data showed that high expression of TRIP4 was positively correlated with increased expression of COX-2 and iNOS and predicted poor prognosis in a cohort of 100 melanoma patients. Collectively, these results show a pro-tumorigenic role of TRIP4, provide an insight into the mechanism of TRIP4 as a candidate therapeutic target, and suggest the potential of TRIP4 and BRAF dual targeting as an effective therapeutic strategy for melanoma.

Lack of XAGE-1b and NY-ESO-1 in metastatic lymph nodes may predict the potential survival of stage III melanoma patients

The cancer-testis antigens (CTA) are a large family of tumor-associated antigens expressed by a variety of cancer cells and primitive germ cells of the adult testis and placenta. These tumor-restricted expressing patterns suggest that CTA would be ideal targets for tumor-specific immunotherapy. XAGE-1 is a CTA that was originally identified by computer-based screening, and four transcription variants, XAGE-1a, -1b, -1c and -1d, have been characterized to date. Although the presence of XAGE-1 transcripts has been reported in various cancers, the expression of XAGE-1b in melanoma has not been fully characterized. In this study, we performed immunohistochemical staining of XAGE-1b together with NY-ESO-1, a well-known CTA, in 113 melanoma samples obtained from 84 patients and evaluated their expression in tumor cells. The effects of expression on tumor progression and patient prognosis were analyzed. Both XAGE-1b and NY-ESO-1 were expressed at high levels in lymph node metastasis and skin metastasis samples compared with the primary site (P < 0.01 in XAGE-1b and P < 0.05 in NY-ESO-1). In a subgroup analysis of 22 patients with stage III lymph node metastasis, overall survival was significantly higher in the XAGE-1b and NY-ESO-1 double-negative group than in the other groups (P < 0.05). These results suggest that lack of XAGE-1b and NY-ESO-1 expression could have a positive influence on clinical outcome in patients with melanoma.

Predictors of tumor-infiltrating lymphocyte efficacy in melanoma

In the past decades, the increasing knowledge in cellular immunology and tumor-host immune interactions, led to the development of immunotherapy approaches. Immunotherapy, based on adoptive cell transfer of ex vivo activated and expanded tumor-infiltrating T lymphocytes (TILs), has shown promising clinical results in patients with metastatic melanoma. TIL therapy yields response rates of around 50% and significant survival benefit in refractory melanoma patients, even after failing other immunotherapies, such as checkpoint inhibitors or cytokine-based therapy. Identifying predictors of TIL efficacy and detection of TIL subsets with specific reactivity against the patient's tumor might be an important milestone toward further improvement of clinical responses and prolonged survival.

Cell Surface CD74-MIF Interactions Drive Melanoma Survival in Response to Interferon-γ

Melanoma is believed to be a highly immunogenic tumor and recent developments in immunotherapies are promising. IFN-γ produced by immune cells has a crucial role in tumor immune surveillance; however, it has also been reported to be pro-tumorigenic. In the current study, we found that IFN-γ enhances the expression of CD74, which interacts with its ligand, macrophage migration inhibitory factor (MIF), and thereby activates the PI3K/AKT pathway in melanoma, promoting tumor survival. IFN-γ increased phosphorylation of AKT Ser473 and upregulated total cell surface expression of CD74 in human melanoma cell lines tested. CD74 was highly expressed in melanoma tissues. Moreover, the expression of CD74 on tumor cells correlated with plasma IFN-γ levels in melanoma patient samples. In our analysis of melanoma cell lines, all produced MIF constitutively. Blockade of CD74-MIF interaction reduced AKT phosphorylation and expression of pro-tumorigenic molecules, including IL-6, IL-8, and BCL-2. Inhibition of CD74-MIF interaction significantly suppressed tumor growth in the presence of IFN-γ in our xenograft mouse model. Thus, we conclude that IFN-γ promotes melanoma cell survival by regulating CD74-MIF signaling, suggesting that targeting the CD74-MIF interaction under IFN-γ-stimulatory conditions would be an effective therapeutic approach for melanoma.

Blockade of A2b adenosine receptor reduces tumor growth and immune suppression mediated by myeloid-derived suppressor cells in a mouse model of melanoma

The A2b receptor (A2bR) belongs to the adenosine receptor family. Emerging evidence suggest that A2bR is implicated in tumor progression in some murine tumor models, but the therapeutic potential of targeting A2bR in melanoma has not been examined. This study first shows that melanoma-bearing mice treated with Bay 60-6583, a selective A2bR agonist, had increased melanoma growth. This effect was associated with higher levels of immune regulatory mediators interleukin-10 (IL-10) and monocyte chemoattractant protein 1 (MCP-1) and accumulation of tumor-associated CD11b positive Gr1 positive cells (CD11b(+)Gr1(+)) myeloid-derived suppressor cells (MDSCs). Depletion of CD11b(+)Gr1(+) cells completely reversed the protumor activity of Bay 60-6583. Conversely, pharmacological blockade of A2bR with PSB1115 reversed immune suppression in the tumor microenvironment, leading to a significant melanoma growth delay. PSB1115 treatment reduced both levels of IL-10 and MCP-1 and CD11b(+)Gr1(+) cell number in melanoma lesions. These effects were associated with higher frequency of tumor-infiltrating CD8 positive (CD8(+)) T cells and natural killer T (NKT) cells and increased levels of T helper 1 (Th1)-like cytokines. Adoptive transfer of CD11b(+)Gr1(+) cells abrogated the antitumor activity of PSB1115. These data suggest that the antitumor activity of PSB1115 relies on its ability to lower accumulation of tumor-infiltrating MDSCs and restore an efficient antitumor T cell response. The antitumor effect of PSB1115 was not observed in melanoma-bearing nude mice. Furthermore, PSB1115 enhanced the antitumor efficacy of dacarbazine. These data indicate that A2bR antagonists such as PSB1115 should be investigated as adjuvants in the treatment of melanoma.

Antibody therapies for melanoma: new and emerging opportunities to activate immunity (Review)

The interface between malignant melanoma and patient immunity has long been recognised and efforts to treat this most lethal form of skin cancer by activating immune responses with cytokine, vaccine and also antibody immunotherapies have demonstrated promise in limited subsets of patients. In the present study, we discuss different antibody immunotherapy approaches evaluated in the context of melanoma, each designed to act on distinct targets and to employ different mechanisms to restrict tumour growth and spread. Monoclonal antibodies recognising melanoma-associated antigens such as CSPG4/MCSP and targeting elements of tumour-associated vasculature (VEGF) have constituted long-standing translational approaches aimed at reducing melanoma growth and metastasis. Recent insights into mechanisms of immune regulation and tumour-immune cell interactions have helped to identify checkpoint molecules on immune (CTLA4, PD-1) and tumour (PD-L1) cells as promising therapeutic targets. Checkpoint blockade with antibodies to activate immune responses and perhaps to counteract melanoma-associated immunomodulatory mechanisms led to the first clinical breakthrough in the form of an anti-CTLA4 monoclonal antibody. Novel modalities to target key mechanisms of immune suppression and to redirect potent effector cell subsets against tumours are expected to improve clinical outcomes and to provide previously unexplored avenues for therapeutic interventions.