Melanoma Differentiation Antigen Research Articles

Pulsed electric field induces exocytosis and overexpression of MAGE antigens in melanoma

Nanosecond pulsed electric field (nsPEF) has emerged as a promising approach for inducing cell death in melanoma, either as a standalone treatment or in combination with chemotherapeutics. However, to date, there has been a shortage of studies exploring the impact of nsPEF on the expression of cancer-specific molecules. In this investigation, we sought to assess the effects of nsPEF on melanoma-specific MAGE (Melanoma Antigen Gene Protein Family) expression. To achieve this, melanoma cells were exposed to nsPEF with parameters set at 8 kV/cm, 200 ns duration, 100 pulses, and a frequency of 10 kHz. We also aimed to comprehensively describe the consequences of this electric field on melanoma cells' invasion and proliferation potential. Our findings reveal that following exposure to nsPEF, melanoma cells release microvesicles containing MAGE antigens, leading to a simultaneous increase in the expression and mRNA content of membrane-associated antigens such as MAGE-A1. Notably, we observed an unexpected increase in the expression of PD-1 as well. While we did not observe significant differences in the cells' proliferation or invasion potential, a remarkable alteration in the cells' metabolomic and lipidomic profiles towards a less aggressive phenotype was evident. Furthermore, we validated these results using ex vivo tissue cultures and 3D melanoma culture models. Our study demonstrates that nsPEF can elevate the expression of membrane-associated proteins, including melanoma-specific antigens. The mechanism underlying the overexpression of MAGE antigens involves the initial release of microvesicles containing MAGE antigens, followed by a gradual increase in mRNA levels, ultimately resulting in elevated expression of MAGE antigens post-experiment. These findings shed light on a novel method for modulating cancer cells to overexpress cancer-specific molecules, thereby potentially enhancing their sensitivity to targeted anticancer therapy.

Loss of p14 diminishes immunogenicity in melanoma via non-canonical Wnt signaling by reducing the peptide surface density.

Immunotherapy has achieved tremendous success in melanoma. However, only around 50% of advanced melanoma patients benefit from immunotherapy. Cyclin-dependent kinase inhibitor 2A (CDKN2A), encoding the two tumor-suppressor proteins p14ARF and p16INK4a, belongs to the most frequently inactivated gene loci in melanoma and leads to decreased Tcell infiltration. While the role of p16INK4a has been extensively investigated, knowledge about p14ARF in melanoma is scarce. In this study, we elucidate the impact of reduced p14ARF expression on melanoma immunogenicity. Knockdown of p14ARF in melanoma cell lines diminished their recognition and killing by melanoma differentiation antigen (MDA)-specific Tcells. Resistance was caused by a reduction of the peptide surface density of presented MDAs. Immunopeptidomic analyses revealed that antigen presentation via human leukocyte antigen class I (HLA-I) molecules was enhanced upon p14ARF downregulation in general, but absolute and relative expression of cognate peptides was decreased. However, this phenotype is associated with a favorable outcome for melanoma patients. Limiting Wnt5a signaling reverted this phenotype, suggesting an involvement of non-canonical Wnt signaling. Taken together, our data indicate a new mechanism limiting MDA-specific Tcell responses by decreasing both absolute and relative MDA-peptide presentation in melanoma.

Autoimmune alleles at the major histocompatibility locus modify melanoma susceptibility

Autoimmunity and cancer represent two different aspects of immune dysfunction. Autoimmunity is characterized by breakdowns in immune self-tolerance, while impaired immune surveillance can allow for tumorigenesis. The class I major histocompatibility complex (MHC-I), which displays derivatives of the cellular peptidome for immune surveillance by CD8+ Tcells, serves as a common genetic link between these conditions. As melanoma-specific CD8+ Tcells have been shown to target melanocyte-specific peptide antigens more often than melanoma-specific antigens, we investigated whether vitiligo- and psoriasis-predisposing MHC-I alleles conferred a melanoma-protective effect. In individuals with cutaneous melanoma from both The Cancer Genome Atlas (n= 451) and an independent validation set (n= 586), MHC-I autoimmune-allele carrier status was significantly associated with a later age of melanoma diagnosis. Furthermore, MHC-I autoimmune-allele carriers were significantly associated with decreased risk of developing melanoma in the Million Veteran Program (OR= 0.962, p= 0.024). Existing melanoma polygenic risk scores (PRSs) did not predict autoimmune-allele carrier status, suggesting these alleles provide orthogonal risk-relevant information. Mechanisms of autoimmune protection were neither associated with improved melanoma-driver mutation association nor improved gene-level conserved antigen presentation relative to common alleles. However, autoimmune alleles showed higher affinity relative to common alleles for particular windows of melanocyte-conserved antigens and loss of heterozygosity of autoimmune alleles caused the greatest reduction in presentation for several conserved antigens across individuals with loss of HLA alleles. Overall, this study presents evidence that MHC-I autoimmune-risk alleles modulate melanoma risk unaccounted for by current PRSs.

Fusion with type 2 macrophages induces melanoma cell heterogeneity that potentiates immunological escape from cytotoxic T lymphocytes.

Evasion from immunity is a major obstacle to the achievement of successful cancer immunotherapy. Hybrids derived from cell-cell fusion are theoretically associated with tumor heterogeneity and progression by conferring novel properties on tumor cells, including drug resistance and metastatic capacity; however, their impact on immune evasion remains unknown. Here, we investigated the potency of tumor-macrophage hybrids in immune evasion. Hybrids were established by co-culture of a melanoma cell line (A375 cells) and type 2 macrophages. The hybrids showed greater migration ability and greater tumorigenicity than the parental melanoma cells. The hybrids showed heterogeneous sensitivity to New York esophageal squamous cell carcinoma-1 (NY-ESO-1)-specific T-cell receptor-transduced T (TCR-T) cells and two out of four hybrid clones showed less sensitivity to TCR-T compared with the parental cells. An in vitro tumor heterogeneity model revealed that the TCR-T cells preferentially killed the parental cells compared with the hybrids and the survival rate of the hybrids was higher than that of the parental cells, indicating that the hybrids evade killing by TCR-T cells efficiently. Analysis of a single-cell RNA sequencing dataset of patients with melanoma revealed that a few macrophages expressed RNA encoding melanoma differentiation antigens including melan A, tyrosinase, and premelanosome protein, which indicated the presence of hybrids in primary melanoma. In addition, the number of potential hybrids was correlated with a poorer response to immune checkpoint blockade. These results provide evidence that melanoma-macrophage fusion has a role in tumor heterogeneity and immune evasion. © 2023 The Pathological Society of Great Britain and Ireland.

SOX10 Inhibits T Cell Recognition by Inducing Expression of the Immune Checkpoint Molecule PD-L1 in A375 Melanoma Cells.

Malignant melanoma is a fatal skin cancer and is among the most immunogenic malignancies expressing melanoma-differentiation antigens and neoantigens. SRY-related HMG-box 10 (SOX10) is a transcription factor and a neural-crest differentiation marker that is used as a diagnostic marker for melanoma whilst playing a role in melanoma initiation through activation of the SOX10-MITF axis. SOX10 was shown to play a role in melanoma initiation by inducing expression of immune checkpoint molecules (e.g., HVEM and CEACAM1). In this study, we aimed to investigate the relationship between SOX10 and the expression an immune checkpoint molecule, programmed death-1 ligand 1 (PD-L1). SOX10 overexpression and knockdown was performed using SOX10 gene transfection and SOX10 siRNA transfection into A375 melanoma cells. PD-L1 expression was assessed by flow cytometry and western blotting. T cell response was evaluated using NY-ESO-1 specific TCR-transduced T (TCR-T) cells by IFNγ ELISPOT assay. SOX10 overexpression increased the expression of PD-L1, whereas SOX10 knockdown, using siRNA, decreased its expression. IFNγ ELISPOT assay revealed that overexpression of SOX10 decreased the susceptibility of cells to NY-ESO-1-specific TCR-T cells. SOX10 has a role in the intrinsic immune suppressive mechanisms of melanoma through expression of PD-L1.

Single cell genomics and immune responses to cancer therapies

Increased tumour infiltrating lymphocytes (TILs) is correlated with improved clinical outcomes. We hypothesised high TILs comprised a distinct functional state. In breast cancer (BC), we showed TILs were significantly increased in primary compared to metastatic disease. Using single cell genomics, high TIL BC had increased CD8+ T cells with a resident memory T cell (TRM) differentiation. BC patients with high TRM gene signature expression and CD8+ T cells had improved progression free and overall survival. In a vaginal melanoma case study, we explored evolution of the melanoma and the patient immune responses. Using longitudinal samples, we investigated whether TRM were present and whether melanoma progression was associated with TRM dysfunction. TRM were the most tumour-responsive and were present in both metastases on the tumour margin. The TRM clonotypes were shared with other T cell clusters in the tumour and the peripheral blood. TRM responded to both melanoma differentiation antigens and a conserved neoantigen (mutated CDKN1C) across both metastatic sites and were significantly increased in the metastasis following anti-PD1 treatment. Finally, we revealed untreated BRAFmut primary, or metastatic melanoma had a distinct immune context to that of BRAFWT disease, providing new evidence to explain the difference in response to immunotherapy.

Single cell genomics and immune responses to cancer therapies

Increased tumour infiltrating lymphocytes (TILs) is correlated with improved clinical outcomes. We hypothesised high TILs comprised a distinct functional state. In breast cancer (BC), we showed TILs were significantly increased in primary compared to metastatic disease. Using single cell genomics, high TIL BC had increased CD8+ T cells with a resident memory T cell (TRM) differentiation. BC patients with high TRM gene signature expression and CD8+ T cells had improved progression free and overall survival. In a vaginal melanoma case study, we explored evolution of the melanoma and the patient immune responses. Using longitudinal samples, we investigated whether TRM were present and whether melanoma progression was associated with TRM dysfunction. TRM were the most tumour-responsive and were present in both metastases on the tumour margin. The TRM clonotypes were shared with other T cell clusters in the tumour and the peripheral blood. TRM responded to both melanoma differentiation antigens and a conserved neoantigen (mutated CDKN1C) across both metastatic sites and were significantly increased in the metastasis following anti-PD1 treatment. Finally, we revealed untreated BRAFmut primary, or metastatic melanoma had a distinct immune context to that of BRAFWT disease, providing new evidence to explain the difference in response to immunotherapy.

Innate immune receptor signaling induces transient melanoma dedifferentiation while preserving immunogenicity

BackgroundImmune-stimulatory agents, like agonists of the innate immune receptor RIG-I, are currently tested in clinical trials as an intratumoral treatment option for patients with unresectable melanoma, aiming to enhance anti-tumor...

Evolution of CD8+ T Cell Receptor (TCR) Engineered Therapies for the Treatment of Cancer.

Engineered T cell receptor T (TCR-T) cell therapy has facilitated the generation of increasingly reliable tumor antigen-specific adaptable cellular products for the treatment of human cancer. TCR-T cell therapies were initially focused on targeting shared tumor-associated peptide targets, including melanoma differentiation and cancer-testis antigens. With recent technological developments, it has become feasible to target neoantigens derived from tumor somatic mutations, which represents a highly personalized therapy, since most neoantigens are patient-specific and are rarely shared between patients. TCR-T therapies have been tested for clinical efficacy in treating solid tumors in many preclinical studies and clinical trials all over the world. However, the efficacy of TCR-T therapy for the treatment of solid tumors has been limited by a number of factors, including low TCR avidity, off-target toxicities, and target antigen loss leading to tumor escape. In this review, we discuss the process of deriving tumor antigen-specific TCRs, including the identification of appropriate tumor antigen targets, expansion of antigen-specific T cells, and TCR cloning and validation, including techniques and tools for TCR-T cell vector construction and expression. We highlight the achievements of recent clinical trials of engineered TCR-T cell therapies and discuss the current challenges and potential solutions for improving their safety and efficacy, insights that may help guide future TCR-T studies in cancer.

BRAF and MEK inhibition in melanoma patients enables reprogramming of tumor infiltrating lymphocytes

BackgroundCombined inhibition of BRAF/MEK is an established therapy for melanoma. In addition to its canonical mode of action, effects of BRAF/MEK inhibitors on antitumor immune responses are emerging. Thus, we investigated the effect of these on adaptive immune responses.Patients, methods and resultsSequential tumor biopsies obtained before and during BRAF/MEK inhibitor treatment of four (n = 4) melanoma patients were analyzed. Multiplexed immunofluorescence staining of tumor tissue revealed an increased infiltration of CD4+ and CD8+ T cells upon therapy. Determination of the T-cell receptor repertoire usage demonstrated a therapy induced increase in T-cell clonotype richness and diversity. Application of the Grouping of Lymphocyte Interactions by Paratope Hotspots algorithm revealed a pre-existing immune response against melanoma differentiation and cancer testis antigens that expanded preferentially upon therapy. Indeed, most of the T-cell clonotypes found under BRAF/MEK inhibition were already present in lower numbers before therapy. This expansion appears to be facilitated by induction of T-bet and TCF7 in T cells, two transcription factors required for self-renewal and persistence of CD8+ memory T cells.ConclusionsOur results suggest that BRAF/MEK inhibition in melanoma patients allows an increased expansion of pre-existing melanoma-specific T cells by induction of T-bet and TCF7 in these.

Comprehensive analysis of cutaneous and uveal melanoma liver metastases

BackgroundThe profound disparity in response to immune checkpoint blockade (ICB) by cutaneous melanoma (CM) and uveal melanoma (UM) patients is not well understood. Therefore, we characterized metastases of CM and...

Interplay between Hepatitis D Virus and the Interferon Response.

Chronic hepatitis D (CHD) is the most severe form of viral hepatitis, with rapid progression of liver-related diseases and high rates of development of hepatocellular carcinoma. The causative agent, hepatitis D virus (HDV), contains a small (approximately 1.7 kb) highly self-pairing single-strand circular RNA genome that assembles with the HDV antigen to form a ribonucleoprotein (RNP) complex. HDV depends on hepatitis B virus (HBV) envelope proteins for envelopment and de novo hepatocyte entry; however, its intracellular RNA replication is autonomous. In addition, HDV can amplify HBV independently through cell division. Cellular innate immune responses, mainly interferon (IFN) response, are crucial for controlling invading viruses, while viruses counteract these responses to favor their propagation. In contrast to HBV, HDV activates profound IFN response through the melanoma differentiation antigen 5 (MDA5) pathway. This cellular response efficiently suppresses cell-division-mediated HDV spread and, to some extent, early stages of HDV de novo infection, but only marginally impairs RNA replication in resting hepatocytes. In this review, we summarize the current knowledge on HDV structure, replication, and persistence and subsequently focus on the interplay between HDV and IFN response, including IFN activation, sensing, antiviral effects, and viral countermeasures. Finally, we discuss crosstalk with HBV.

BRAF Inhibitors: Molecular Targeting and Immunomodulatory Actions.

The BRAF inhibitors vemurafenib, dabrafenib and encorafenib are used in the treatment of patients with BRAF-mutant melanoma. They selectively target BRAF kinase and thus interfere with the mitogen-activated protein kinase (MAPK) signalling pathway that regulates the proliferation and survival of melanoma cells. In addition to their molecularly targeted activity, BRAF inhibitors have immunomodulatory effects. The MAPK pathway is involved in T-cell receptor signalling, and interference in the pathway by BRAF inhibitors has beneficial effects on the tumour microenvironment and anti-tumour immune response in BRAF-mutant melanoma, including increased immune-stimulatory cytokine levels, decreased immunosuppressive cytokine levels, enhanced melanoma differentiation antigen expression and presentation of tumour antigens by HLA 1, and increased intra-tumoral T-cell infiltration and activity. These effects promote recognition of the tumour by the immune system and enhance anti-tumour T-cell responses. Combining BRAF inhibitors with MEK inhibitors provides more complete blockade of the MAPK pathway. The immunomodulatory effects of BRAF inhibition alone or in combination with MEK inhibition provide a rationale for combining these targeted therapies with immune checkpoint inhibitors. Available data support the synergy between these treatment approaches, indicating such combinations provide an additional beneficial effect on the tumour microenvironment and immune response in BRAF-mutant melanoma.

Innate immune recognition and modulation in hepatitis D virus infection.

Hepatitis D virus (HDV) is a global health threat with more than 15 million humans affected. Current treatment options are largely unsatisfactory leaving chronically infected humans at high risk to develop liver cirrhosis and hepatocellular carcinoma. HDV is the only human satellite virus known. It encodes only two proteins, and requires Hepatitis B virus (HBV) envelope protein expression for productive virion release and spread of the infection. How HDV could evolve and why HBV was selected as a helper virus remains unknown. Since the discovery of Na+-taurocholate co-transporting polypeptide as the essential uptake receptor for HBV and HDV, we are beginning to understand the interactions of HDV and the immune system. While HBV is mostly regarded a stealth virus, that escapes innate immune recognition, HBV-HDV coinfection is characterized by a strong innate immune response. Cytoplasmic RNA sensor melanoma differentiation antigen 5 has been reported to recognize HDV RNA replication and activate innate immunity. Innate immunity, however, seems not to impair HDV replication while it inhibits HBV. In this review, we describe what is known up-to-date about the interplay between HBV as a helper and HDV’s immune evasion strategy and identify where additional research is required.

Human PSC-Derived Hepatocytes Express Low Levels of Viral Pathogen Recognition Receptors, but Are Capable of Mounting an Effective Innate Immune Response.

Hepatocytes are key players in the innate immune response to liver pathogens but are challenging to study because of inaccessibility and a short half-life. Recent advances in in vitro differentiation of hepatocyte-like cells (HLCs) facilitated studies of hepatocyte–pathogen interactions. Here, we aimed to define the anti-viral innate immune potential of human HLCs with a focus on pattern recognition receptor (PRR)-expression and the presence of a metabolic switch. We analysed cytoplasmic PRR and endosomal toll-like receptor (TLR)-expression, as well as activity and adaptation of HLCs to an inflammatory environment. We found that transcript levels of retinoic acid inducible gene I (RIG-I), melanoma differentiation antigen 5 (MDA5), and TLR3 became downregulated during differentiation, indicating the acquisition of a more tolerogenic phenotype, as expected in healthy hepatocytes. HLCs responded to activation of RIG-I by producing interferons (IFNs) and IFN-stimulated genes. Despite low-level levels of TLR3, receptor expression was upregulated in an inflammatory environment. TLR3 signalling induced expression of proinflammatory cytokines at the gene level, indicating that several PRRs need to interact for successful innate immune activation. The inflammatory responsiveness of HLCs was accompanied by the downregulation of cytochrome P450 3A and 1A2 activity and decreased serum protein production, showing that the metabolic switch seen in primary hepatocytes during anti-viral responses is also present in HLCs.

Phase I study of a new concept cancer vaccine composed artificial intelligence (AI)-designed shared-antigen peptides plus combined synergistically activating antigen-specific CTL reaction (CYT001) in patients with advanced hepatocellular carcinoma (CRESCENT 1).

TPS595 Background: CYT001 (CYTLIMIC Inc.) is a novel cancer vaccine involving artificial intelligence (AI)-designed shared-antigen peptides and optimal combined adjuvants that boost the cancer-immunity cycle. The two multi-HLA reactive peptides heat shock protein 70 (HSP70) and glypican 3 (GPC3) were screened by an AI-based prediction system according to the proteome, mRNA, and histopathology data fromhuman samples. These immunogenic peptides were confirmed to show cross-reactivity to HLA-A 24:02, 02:01, and 02:06. Poly-ICLC (Oncovir Inc.) binds to Toll-like receptor 3 (TLR3) and melanoma differentiation antigen 5 (MDA5) on antigen-presenting cells (APCs)and activates APCs. LAG-3Ig (Immutep Inc.) binds to the major histocompatibility complex (MHC) class II molecules of APCs and activates APCs. Both poly-ICLC and LAG-3Ig synergistically activate antigen-specific CTL reactions as effective combination adjuvants. The present study aims to evaluate the safety and tolerability of CYT001 (mixture of HSP70 peptide [2.0 mg], GPC3 peptide [2.0 mg], poly-ICLC [1.0 mg], and LAG-3Ig [1.4 mg]) in patients with advanced hepatocellular carcinoma (HCC). Methods: This is a single-center, phase 1, open-label, single-arm, investigator-initiated clinical trial of CYT001 for advanced HCC patients with no eligible standard systemic therapy, Child–Pugh A liver disease, and HLA-A 24:02, 02:01, or 02:06. Enrolled patients will receive CYT001 as a subcutaneous injection on days 1, 8, 15, and 21 in the 1st and 2nd cycles, days 1 and 15 in the 3rd and 4th cycles, and day 1 in the 5th cycle or later of 28-day cycles. The primary endpoint is dose-limiting toxicity, and the secondary endpoints are safety and the response rate. The transition of the CTL reactions of both the HSP70 and GPC3 peptides will be evaluated using blood samples of the subjects. Exploratory analyses include investigation of candidate biomarkers for treatment efficacy using liver tumor biopsy samples (baseline and after the 1st cycle) and blood samples (baseline and every days of administration). Clinical trial information: jRCT2031190072.

ER‐aminopeptidase 1 determines the processing and presentation of an immunotherapy‐relevant melanoma epitope

Dissecting the different steps of the processing and presentation of tumor-associated antigens is a key aspect of immunotherapies enabling to tackle the immune response evasion attempts of cancer cells. The immunodominant glycoprotein gp100209-217 epitope, which is liberated from the melanoma differentiation antigen gp100PMEL17 , is part of immunotherapy trials. By analyzing different human melanoma cell lines, we here demonstrate that a pool of N-terminal extended peptides sharing the common minimal epitope is generated by melanoma proteasome subtypes. In vitro and in cellulo experiments indicate that ER-resident aminopeptidase 1 (ERAP1)-but not ERAP2-defines the processing of this peptide pool thereby modulating the T-cell recognition of melanoma cells. By combining the outcomes of our studies and others, we can sketch the complex processing and endogenous presentation pathway of the gp100209-217 -containing epitope/peptides, which are produced by proteasomes and are translocated to the vesicular compartment through different pathways, where the precursor peptides that reach the endoplasmic reticulum are further processed by ERAP1. The latter step enhances the activation of epitope-specific T lymphocytes, which might be a target to improve the efficiency of anti-melanoma immunotherapy.

A phase I study (E011-MEL) of a TriMix-based mRNA immunotherapy (ECI-006) in resected melanoma patients: Analysis of safety and immunogenicity.

2641 Background: ECI-006 is a combination of TriMix (mRNAs encoding for dendritic cell [DC] activating molecules [CD40L, CD70 and caTLR4]), and mRNAs encoding for melanoma-specific tumor-associated antigens (TAAs): tyrosinase, gp100, MAGE-A3, MAGE-C2, and PRAME. DCs transfected ex vivo with TriMix and TAAs mRNAs showed significant clinical activity in combination with ipilimumab in metastatic melanoma without increasing toxicity. This study aims to assess the safety and immunogenicity of ECI-006 vaccine administered intranodally (i.n.) in an adjuvant setting for patients with resected melanoma. Methods: Twenty patients who underwent resection of stage IIc/III/IV cutaneous melanoma received 5 administrations of ECI-006 (either 600 µg or 1800 µg [n = 10, each]) injected i.n. on Day 1 and after 2, 4, 6 and 14 weeks. Treatment-emergent adverse events (TEAEs) were graded using CTCAE version 4.0.3. Blood samples for immune monitoring (ELISPOT and intracellular cytokine staining [ICS]) were collected pre-dose and at weeks 4, 7, 14 and 15. Results: Nineteen patients completed the treatment. One patient in the low dose group discontinued the study after 4 doses due to disease relapse. Administration of ECI-006 was well tolerated. No serious adverse events or TEAEs Grade 3 or higher were reported. Of all TEAEs, myalgia and fatigue were the most reported in 3 (15%) and 5 (25%) patients, respectively. ELISPOT and ICS were performed on T cells pre-stimulated in vitro for 10-12 days, using a previously in-house validated protocol. Vaccine-induced immune responses according to predefined criteria were detected in 4/10 and 3/9 patients treated with the low and high dose, respectively. Samples from these patients are currently being subjected to T-cell receptor repertoire analysis. Conclusions: Among patients undergoing resection of stage IIc/III/IV melanoma, i.n. administration of ECI-006 at 600 or 1800 µg was generally well tolerated. ECI-006 demonstrated to be immunogenic in a proportion of patients. These results warrant further development of ECI-006 in combination with anti-PD-1 therapy in melanoma patients. Clinical trial information: NCT03394937.

CCR5 is a required signaling receptor for macrophage expression of inflammatory genes in response to viral double-stranded RNA.

Double-stranded (ds) RNA, both synthetic and produced during virus replication, rapidly stimulates MAPK and NF-κB signaling that results in expression of the inflammatory genes inducible nitric oxide synthase, cyclooxygenase 2, and IL-1β by macrophages. Using biochemical and genetic approaches, we have identified the chemokine ligand-binding C-C chemokine receptor type 5 (CCR5) as a cell surface signaling receptor required for macrophage expression of inflammatory genes in response to dsRNA. Activation of macrophages by synthetic dsRNA does not require known dsRNA receptors, as poly(inosinic:cytidylic) acid [poly(I:C)] activates signaling pathways leading to expression of inflammatory genes to similar levels in wild-type and Toll-like receptor 3- or melanoma differentiation antigen 5-deficient macrophages. In contrast, macrophage activation in response to poly(I:C) is attenuated in macrophages isolated from mice lacking CCR5. These findings support a role for CCR5 as a cell surface signaling receptor that participates in activation of inflammatory genes in macrophages in response to the viral dsRNA mimetic poly(inosinic:cytidylic) acid by pathways that are distinct from classical dsRNA receptor-mediated responses.

Combined targeted therapy and immunotherapy in melanoma: a review of the impact on the tumor microenvironment and outcomes of early clinical trials.

The development of BRAF and MEK inhibitors (BRAFis and MEKis) and immune checkpoint inhibitors have changed the management of advanced stage melanoma and improved the outcomes of patients with this malignancy. However, both therapeutic approaches have limitations, including a limited duration of benefit in subsets of BRAF-mutant melanoma patients treated with targeted therapy and a lower overall response rate without a clear predictive biomarker in patients treated with checkpoint inhibitors. Preclinical and translational data have shown that BRAFis and MEKis alter the tumor microenvironment to make it more amenable to immunotherapy and have provided the scientific rationale for combing BRAFis and MEKis with immunotherapy. In this review, the initial studies demonstrating the impact of BRAFis and MEKis on the expression of melanoma differentiation antigens, T-cell infiltration, and the balance of immune stimulatory and immune suppressive cells and cytokines are addressed. Preclinical work on the combination of targeted therapy with BRAFis and MEKis with immunotherapy are reviewed, highlighting improved tumor responses in mouse models of BRAF-mutated melanoma treated with combinatorial strategies. Lastly, data from early clinical trials of combined targeted therapy and immunotherapy are discussed, focusing on response rates and toxicities.