Identification and validation of a costimulatory molecule-related signature to predict the prognosis for uveal melanoma patients

Uveal melanoma (UVM) is the most common primary tumor in adult human eyes. Costimulatory molecules (CMs) are important in maintaining T cell biological functions and regulating immune responses. To investigate the role of CMs in UVM and exploit prognostic signature by bioinformatics analysis. This study aimed to identify and validate a CMs associated signature and investigate its role in the progression and prognosis of UVM. The expression profile data of training cohort and validation cohort were downloaded from The Cancer Genome Atlas (TCGA) dataset and the Gene Expression Omnibus (GEO) dataset. 60 CM genes were identified, and 34 genes were associated with prognosis by univariate Cox regression. A prognostic signature was established with six CM genes. Further, high- and low-risk groups were divided by the median, and Kaplan-Meier (K-M) curves indicated that high-risk patients presented a poorer prognosis. We analyzed the correlation of gender, age, stage, and risk score on prognosis by univariate and multivariate regression analysis. We found that risk score was the only risk factor for prognosis. Through the integration of the tumor immune microenvironment (TIME), it was found that the high-risk group presented more immune cell infiltration and expression of immune checkpoints and obtained higher immune scores. Enrichment analysis of the biological functions of the two groups revealed that the differential parts were mainly related to cell-cell adhesion, regulation of T-cell activation, and cytokine-cytokine receptor interaction. No differences in tumor mutation burden (TMB) were found between the two groups. GNA11 and BAP1 have higher mutation frequencies in high-risk patients. Finally, based on the Genomics of Drug Sensitivity in Cancer 2 (GDSC2) dataset, drug sensitivity analysis found that high-risk patients may be potential beneficiaries of the treatment of crizotinib or temozolomide. Taken together, our CM-related prognostic signature is a reliable biomarker that may provide ideas for future treatments for the disease.

A One-Armed Phase I Dose Escalation Trial Design: Personalized Vaccination with IKKβ-Matured, RNA-Loaded Dendritic Cells for Metastatic Uveal Melanoma

Uveal melanoma (UM) is an orphan disease with a mortality of 80% within one year upon the development of metastatic disease. UM does hardly respond to chemotherapy and kinase inhibitors and is largely resistant to checkpoint inhibition. Hence, further therapy approaches are urgently needed. To improve clinical outcome, we designed a trial employing the 3^rd generation personalized IKKβ-matured RNA-transfected dendritic cell (DC) vaccine which primes T cells and in addition activates NK cells. This ongoing phase I trial [NCT04335890 (www.clinicaltrials.gov), Eudract: 2018-004390-28 (www.clinicaltrialsregister.eu)] investigates patients with treatment-naive metastatic UM. Monocytes are isolated by leukapheresis, differentiated to immature DCs, matured with a cytokine cocktail, and activated via the NF-κB pathway by electroporation with RNA encoding a constitutively active mutant of IKKβ. Three types of antigen-RNA are co-electroporated: i) amplified mRNA of the tumor representing the whole transcriptome, ii) RNA encoding driver mutations identified by exome sequencing, and iii) overexpressed non-mutated tumor antigens detected by transcriptome sequencing. This highly personalized DC vaccine is applied by 9 intravenous infusions in a staggered schedule over one year. Parallel to the vaccination, standard therapy, usually an immune checkpoint blockade (ICB) as mono (anti-PD-1) or combined (anti-CTLA4 and anti-PD-1) regimen is initiated. The coordinated vaccine-induced immune response encompassing tumor-specific T cells and innate NK cells should synergize with ICB, perhaps resulting in measurable clinical responses in this resistant tumor entity. Primary outcome measures of this trial are safety, tolerability and toxicity; secondary outcome measures comprise overall survival and induction of antigen-specific T cells.

The immune cell landscape of metastatic uveal melanoma correlates with overall survival

BACKGROUND

Uveal melanoma (UM) represents the most common primary intra-ocular malignancy in adults. Up to 50% of the patients develop distant metastases within 10 years from diagnosis, with the liver as the most common site. Upon metastatization, life expectancy strongly reduces and immune checkpoint inhibitors that prove effective in cutaneous melanoma do not modify clinical outcome. To date, few studies have focused on deciphering the immunomodulatory features of metastatic UM microenvironment, and there are no prognostic models for clinical use. This highlights the urgent need to understand the delicate interplay between tumor and immune cells acting at the site of metastasis.

METHODS

We collected a patient cohort comprising 21 metastatic UM patients. Hepatic and extra-hepatic UM metastasis samples were studied by multiplex immunofluorescence to assess the tumor immune cell composition. Quantitative analyses were performed to correlate immune cell densities with treatment response, metastasis site and patient survival.

RESULTS

Compared to patients with progressive disease, those with controlled disease had a higher intra-tumoral/peritumoral ratio of CD8 + Granzyme B+ cells, higher density of intra-tumoral CD8+ cytotoxic T lymphocytes (CTL) and an increased percentage of UM cells in close proximity to T lymphocytes, reflecting a role of tumor-killing T cells in the disease. In liver metastases (LM), the intra-tumoral densities of CD163+ tumor-associated macrophages (TAM) and of total CD8+ T cells were higher than in extra-hepatic UM metastases, but the percentage of Granzyme B+ CTL was lower. Moreover, LM displayed more UM cells adjacent to both CTL and TAM, and also more T cells in proximity to TAM, all signs of an impaired immune response. The percentage of activated CTL within the tumor represented a prognostic indicator, as patients with a higher intra-tumoral percentage of CD8 + Granzyme B+ cells had the better outcome. A temptative Immunoscore was generated and proved capable to stratify patients with improved survival. Finally, CD4 + FoxP3+ T cells appeared a crucial population for response to immunotherapy.

CONCLUSION

The results of this study underly the clinical relevance and functional importance of composition and localization of antitumor effector cells for the progression of UM metastasis.

The Genetic Evolution of Treatment-Resistant Cutaneous, Acral, and Uveal Melanomas

PURPOSE

Melanoma is a biologically heterogeneous disease composed of distinct clinicopathologic subtypes that frequently resist treatment. To explore the evolution of treatment resistance and metastasis, we used a combination of temporal and multilesional tumor sampling in conjunction with whole-exome sequencing of 110 tumors collected from 7 patients with cutaneous (n = 3), uveal (n = 2), and acral (n = 2) melanoma subtypes.

EXPERIMENTAL DESIGN

Primary tumors, metastases collected longitudinally, and autopsy tissues were interrogated. All but 1 patient died because of melanoma progression.

RESULTS

For each patient, we generated phylogenies and quantified the extent of genetic diversity among tumors, specifically among putative somatic alterations affecting therapeutic resistance.

CONCLUSIONS

In 4 patients who received immunotherapy, we found 1-3 putative acquired and intrinsic resistance mechanisms coexisting in the same patient, including mechanisms that were shared by all tumors within each patient, suggesting that future therapies directed at overcoming intrinsic resistance mechanisms may be broadly effective.

A Comprehensive Prognostic and Immunological Analysis of a Six-Gene Signature Associated With Glycolysis and Immune Response in Uveal Melanoma

Uveal melanoma (UM) is a subtype of melanoma with poor prognosis. This study aimed to construct a new prognostic gene signature that can be used for survival prediction and risk stratification of UM patients. In this work, transcriptome data from the Molecular Signatures Database were used to identify the cancer hallmarks most relevant to the prognosis of UM patients. Weighted gene co-expression network, univariate least absolute contraction and selection operator (LASSO), and multivariate Cox regression analyses were used to construct the prognostic gene characteristics. Kaplan-Meier and receiver operating characteristic (ROC) curves were used to evaluate the survival predictive ability of the gene signature. The results showed that glycolysis and immune response were the main risk factors for overall survival (OS) in UM patients. Using univariate Cox regression analysis, 238 candidates related to the prognosis of UM patients were identified (p < 0.05). Using LASSO and multivariate Cox regression analyses, a six-gene signature including ARPC1B, BTBD6, GUSB, KRTCAP2, RHBDD3, and SLC39A4 was constructed. Kaplan-Meier analysis of the UM cohort in the training set showed that patients with higher risk scores had worse OS (HR = 2.61, p < 0.001). The time-dependent ROC (t-ROC) curve showed that the risk score had good predictive efficiency for UM patients in the training set (AUC > 0.9). Besides, t-ROC analysis showed that the predictive ability of risk scores was significantly higher than that of other clinicopathological characteristics. Univariate and multivariate Cox regression analyses showed that risk score was an independent risk factor for OS in UM patients. The prognostic value of risk scores was further verified in two external UM cohorts (GSE22138 and GSE84976). Two-factor survival analysis showed that UM patients with high hypoxia or immune response scores and high risk scores had the worst prognosis. Moreover, a nomogram based on the six-gene signature was established for clinical practice. In addition, risk scores were related to the immune infiltration profiles. Taken together, this study identified a new prognostic six-gene signature related to glycolysis and immune response. This six-gene signature can not only be used for survival prediction and risk stratification but also may be a potential therapeutic target for UM patients.

Molecular profiling of driver events in metastatic uveal melanoma

Metastatic uveal melanoma is less well understood than its primary counterpart, has a distinct biology compared to skin melanoma, and lacks effective treatments. Here we genomically profile metastatic tumors and infiltrating lymphocytes. BAP1 alterations are overrepresented and found in 29/32 of cases. Reintroducing a functional BAP1 allele into a deficient patient-derived cell line, reveals a broad shift towards a transcriptomic subtype previously associated with better prognosis of the primary disease. One outlier tumor has a high mutational burden associated with UV-damage. CDKN2A deletions also occur, which are rarely present in primaries. A focused knockdown screen is used to investigate overexpressed genes associated withcopy number gains. Tumor-infiltrating lymphocytes are in several cases found tumor-reactive, but expression of the immune checkpoint receptors TIM-3, TIGIT and LAG3 is also abundant. This study represents the largest whole-genome analysis of uveal melanoma to date, and presents an updated view of the metastatic disease.

Anthropometry in the immunotherapy of cutaneous and ocular melanomas

The height of the adult individual is a balance of the expression of some genetic factors (especially the Y-M 170 haplotype of the Y chromosome) and the environment (nutrition and morbidity during childhood). Higher height is associated with a low risk of developing coronary heart disease, hypertension, gastroesophageal reflux, diaphragmatic hernia, but with a higher risk for atrial fibrillation, venous thromboembolism, intervertebral disc pathology, vasculitis and cancer. The research consisted of a retrospective observational study on patients who received immunotherapy (IT) with nivolumab for cutaneous and ocular melanoma neoplasms. We intended to highlight the associations between the duration of immunotherapy and sex profiles, age, anthropometric data (height, weight). Even though the number of available cases was relatively small (42), an inverse association between the body mass index of the subjects and the duration of immunotherapy could be proved, a more expressed association in case of male patients.

The Role of Immune Checkpoint Blockade in Uveal Melanoma

Uveal melanoma (UM) represents the most common intraocular malignancy in adults and accounts for about 5% of all melanomas. Primary disease can be effectively controlled by several local therapy options, but UM has a high potential for metastatic spread, especially to the liver. Despite its clinical and genetic heterogeneity, therapy of metastatic UM has largely been adopted from cutaneous melanoma (CM) with discouraging results until now. The introduction of antibodies targeting CTLA-4 and PD-1 for immune checkpoint blockade (ICB) has revolutionized the field of cancer therapy and has achieved pioneering results in metastatic CM. Thus, expectations were high that patients with metastatic UM would also benefit from these new therapy options. This review provides a comprehensive and up-to-date overview on the role of ICB in UM. We give a summary of UM biology, its clinical features, and how it differs from CM. The results of several studies that have been investigating ICB in metastatic UM are presented. We discuss possible reasons for the lack of efficacy of ICB in UM compared to CM, highlight the pitfalls of ICB in this cancer entity, and explain why other immune-modulating therapies could still be an option for future UM therapies.

HER2 CAR-T Cells Eradicate Uveal Melanoma and T-cell Therapy-Resistant Human Melanoma in IL2 Transgenic NOD/SCID IL2 Receptor Knockout Mice

Chimeric antigen receptors (CAR) can transmit signals akin to those from activated T-cell receptors when bound to a cell surface target. CAR-expressing T cells against CD19 can cause curative effects in leukemia and lymphoma and is approved for clinical use. However, no CAR-T therapy is currently approved for use in solid tumors. We hypothesize that the resistance of solid tumors to CAR-T can be overcome by similar means as those used to reactivate tumor-infiltrating T lymphocytes (TIL), for example, by cytokines or immune checkpoint blockade. Here we demonstrate that CAR-T cells directed against HER2 can kill uveal and cutaneous melanoma cells in vitro and in vivo. Curative effects in vivo were only observed in xenografts grown in a NOD/SCID IL2 receptor gamma (NOG) knockout mouse strain transgenic for human IL2. The effect was target-specific, as CRISPR/Cas9-mediated disruption of HER2 in the melanoma cells abrogated the killing effect of the CAR-T cells. The CAR-T cells were also able to kill melanoma cells from patients resistant to adoptive T-cell transfer (ACT) of autologous TILs. Thus, CAR-T therapy represents an option for patients that do not respond to immunotherapy with ACT of TIL or immune checkpoint blockade. In addition, our data highlight the use of IL2 transgenic NOG mice as models to prove efficacy of CAR-T-cell products, possibly even in a personalized manner. SIGNIFICANCE: These findings demonstrate that a novel humanized mouse model can help clinical translation of CAR-T cells against uveal and cutaneous melanoma that do not respond to TIL therapy or immune checkpoint blockade.

Cytokines concentrations in aqueous humor of eyes with uveal melanoma

Uveal melanoma (UM) is the major intraocular malignancy in adults, of which the molecular biology is still unknown. Therefore, this study was designed to determine the aqueous concentrations of angiogenic, inflammatory, and chemotactic cytokines in eyes with UM.Aqueous humor samples were collected from 38 patients with UM and 22 patients undergoing cataract surgery. Interleukin 6, 8 (IL-6, IL-8, respectively), interferon-inducible protein-10 (IP-10), placental growth factor1 (PIGF1), regulated on activation, normal T Cell expressed and secreted (RANTES), monocyte chemoattractant protein-1 (MCP-1), nerve growth factor-beta (NGF-β), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and vascular endothelia growth factor A (VEGF-A) were assessed by multiplex bead assay.In the study group, significantly higher concentrations of IL-6 (P = .006), IL-8 (P = .018), IP-10 (P = .004), RANTES (P = .008), MCP-1 (P = .02), NGF-β (P = .013), EGF (P < .001), PIGF1 (P = .01), bFGF (P = .016), and VEGF (P = .017) were measured, when compared with the control group.Several angiogenic, inflammatory, and chemotactic cytokines are highly expressed in the aqueous humor of the UM eyes, which provides new insights into the pathophysiology of UM and could be potential targets for treatment.

Immunotherapy for the Treatment of Uveal Melanoma: Current Status and Emerging Therapies

PURPOSE OF REVIEW

Uveal melanoma is a distinct subset of melanoma with a biology and treatment approach that is unique from that of cutaneous melanoma. Here we will review the current data evaluating immunotherapies in both the adjuvant and metastatic settings in uveal melanoma.

RECENT FINDINGS

In the adjuvant setting, interferon demonstrated no survival benefit in uveal melanoma, and studies evaluating immune-based strategies such as vaccine therapy are ongoing. Anti-CTLA-4 and anti-PD-1/ PD-L1 blockade in uveal melanoma have been evaluated in several small prospective and/or retrospective studies with rare responses and no overall survival benefit demonstrated. Ongoing studies evaluating combination checkpoint inhibition and other antibody-based therapies are ongoing. Although immunotherapy with anti-CTLA-4 and anti-PD-1 agents has dramatically changed the treatment approach to cutaneous melanoma, its success in uveal melanoma has been much more limited. Clinical trial participation should be prioritized in patients with uveal melanoma.

Inflammatory cell infiltrates in advanced metastatic uveal melanoma

Current treatments for metastatic uveal melanoma (mUM) are limited and rarely prolong patient survival. Immunotherapy trials for mUM are few and to date have demonstrated only marginal success. High densities of tumor-associated macrophages (TAMs) and infiltrating T lymphocytes (TILs) in primary UM are associated with poor prognosis. Little is known about the immune microenvironment of mUM. Our aim was to examine the presence and distribution of TAMs and TILs in mUM within the liver. Whole-tissue sections of liver mUM (n=35) were examined by immunohistochemistry. For TAMs, monoclonal antibodies against CD68 and CD163 were used. Macrophage density and morphology were scored using previous established systems. Density and spatial distribution of TILs were highlighted using antibodies against CD3 (pan-lymphocyte marker), CD4 (T-helper cells), and CD8 (T-cytotoxic cells). CD68+ and CD163+ TAMs were seen within the tumor in all 35 specimens; their density was "moderate" in 50% of cases and "few" in 43%, and the majority showed an "indeterminate" phenotype. CD3+ TILs were noted both within mUMs and surrounding the tumor. Of these, CD8+ TILs were "few" in number within mUM but were predominantly seen peritumorally at the tumor/normal liver interface, whereas CD4+ TILs showed a high perivascular density within mUM. CD68+ and CD163+ TAMs of "indeterminate" morphology were observed in mUM, suggesting a tendency toward the protumorigenic M2 phenotype. CD4+ TILs were seen within the mUM, whereas CD8+ TILs tended to be peritumoral. The biological and functional roles of inflammatory cells in mUM require further investigation to determine if they represent potential targets for future therapies in mUM.

Uveal Melanoma: Identifying Immunological and Chemotherapeutic Targets to Treat Metastases

Uveal melanoma is an intraocular malignancy that, depending on its size and genetic make-up, may lead to metastases in up to 50% of cases. Currently, no therapy has been proven to improve survival. However, new therapies exploiting immune responses against metastases are being developed. The primary tumor is well characterized: tumors at high risk of developing metastases often contain macrophages and lymphocytes. However, these lymphocytes are often regulatory T cells that may suppress immune response. Currently, immune checkpoint inhibitors have shown marked efficacy in multiple cancers (eg, cutaneous melanoma) but do not yet improve survival in uveal melanoma patients. More knowledge needs to be acquired regarding the function of T cells in uveal melanoma. Other therapeutic options are related to the biochemical pathways. Targeting the RAF-MEK-ERK pathway with small molecule MEK inhibitors abrogates the growth of UM cells harboring GNAQ/GNA11 Q209 mutations, suggesting that these aberrant G-protein oncogenes mediate, at least in part, their effect through this hallmark proliferation pathway. Other pathways are also implicated, such as those involving c-Jun and YAP. Further studies may show how interference in the different pathways may affect survival.

Immunotherapy of Uveal Melanoma: Vaccination Against Cancer

Uveal melanoma is the most frequently occurring primary intraocular tumor in adults, with an incidence of about 5 out of 100,000 per year, the incidence rising with increasing age (Lipski, Klin Monbl Augenheilkd 230:1005-1019, 2013; Metz et al., Klin Monbl Augenheilkd 230:686-691, 2013; Singh and Topham, Ophthalmology 110:956-961, 2003). Often diagnosed late due to a lack of early symptoms, this kind of melanoma is associated with a poor prognosis. Approximately 50 % of the patients develop distant metastases (Lipski, Klin Monbl Augenheilkd 230:1005-1019, 2013; Metz et al., Klin Monbl Augenheilkd 230:686-691, 2013; Singh and Topham, Ophthalmology 110:956-961, 2003). In sharp contrast to cutaneous melanoma, uveal melanoma shows a strong liver tropism and spreads exclusively via the hematogenous route (except for tumors with extraocular expansion) (Heindl et al., Arch Ophthalmol 128:1001-1008, 2010). The most likely reason for this observation is the lack of lymphatic vessels in the choroid and alymphatic barrier of the sclera (Schlereth et al., Exp Eye Res 125:203-209, 2014; Schroedl et al., Invest Ophthalmol Vis Sci 49:5222-5229, 2008). Due to its location in the immune-privileged eye, the uveal melanoma is widely protected from the immune system. Therefore, the goal of the approach presented here, of a "personalized vaccination therapy" is to help the immune system recognize and fight the tumor.

[Immunotherapy of uveal melanoma: vaccination against cancer. Multicenter adjuvant phase 3 vaccination study using dendritic cells laden with tumor RNA for large newly diagnosed uveal melanoma]

Uveal melanomas are the most common malignant tumors of the eye. With modern molecular biological diagnostic methods, such as chromosome 3 typing and gene expression analysis, these tumors can be categorized into highly aggressive (monosomy 3, class II) and less aggressive forms. This molecular biological stratification is primarily important for determining the risk of these tumors as no therapy is currently available that is able to prevent or delay metastases. A randomized study of patients with a poor prognosis (monosomy 3) is currently being carried out in order to determine whether a cancer vaccine prepared from autologous (patient's own) dendritic cells and uveal melanoma RNA can prevent or delay progression and further metastases of this extremely aggressive form of cancer. Inclusion in the uveal melanoma study, which hopes to provide a potential therapeutic option for patients, is only possible if patients are referred to an institution that is able to manufacture and provide this vaccination before the patient is operated on or treated with radiation. Untreated tumor material is necessary for producing the vaccine on an individualized patient basis.

Clinical outcomes in metastatic uveal melanoma treated with PD-1 and PD-L1 antibodies

BACKGROUND

Antibodies inhibiting the programmed death receptor 1 (PD-1) have demonstrated significant activity in the treatment of advanced cutaneous melanoma. The efficacy and safety of PD-1 blockade in patients with uveal melanoma has not been well characterized.

METHODS

Fifty-eight patients with stage IV uveal melanoma received PD-1 or PD-1 ligand (PD-L1) antibodies between 2009 and 2015 at 9 academic centers. Patients who were evaluable for response were eligible for the analysis. Imaging was performed every 12 weeks and at the investigators' discretion. Safety and clinical efficacy outcomes, including the best overall response, progression-free survival (PFS), and overall survival (OS), were retrospectively determined.

RESULTS

Of 56 eligible patients, 48 (86%) had received prior therapy, and 35 (63%) had received treatment with ipilimumab. Three patients had an objective response to ipilimumab, and 8 had stable disease as their best response. Thirty-eight patients (68%) received pembrolizumab, 16 (29%) received nivolumab, and 2 (4%) received atezolizumab. Objective tumor responses were observed in 2 patients for an overall response rate of 3.6% (95% confidence interval [CI], 1.8%-22.5%). Stable disease (≥6 months) was observed in 5 patients (9%). The median PFS was 2.6 months (95% CI, 2.4-2.8 months), and the median OS was 7.6 months (95% CI, 0.7-14.6 months). There was no association between prior treatment with ipilimumab or liver-directed therapy and PFS or OS. Treatment was well tolerated, and only 1 patient discontinued treatment because of toxicity.

CONCLUSIONS

PD-1 and PD-L1 antibodies rarely confer durable remissions in patients with metastatic uveal melanoma. Clinical trial enrollment should be prioritized in this population. Cancer 2016;122:3344-3353. © 2016 American Cancer Society.

Uveal Spindle Cell Tumor of Blue-Eyed Dogs: An Immunohistochemical Study

Immunohistochemical techniques were used to investigate the origin of a spindle cell tumor in the anterior uveal tract of dogs and the influence of ultraviolet radiation on the development of this tumor. Thirteen tumors were identified from the 4,007 canine ocular samples examined at the Comparative Ocular Pathology Laboratory of Wisconsin between 1978 and 2005. Siberian Husky and Siberian Husky mix dogs were overrepresented (10/13 dogs, overall median age 10 years). Light microscopic evaluation (all dogs) and electron microscopy (2 dogs) were performed. Immunohistochemical staining included alpha-smooth muscle actin (SMA), vimentin, S-100, desmin, glial fibrillary acidic protein (GFAP), Melan A, microphthalmic transcription factor (MITF-1), protein gene product 9.5 (PGP 9.5), laminin, gadd45, p53, proliferating cell nuclear antigen (PCNA), anti-UVssDNA (antibody for detection of (6–4)-dipyrimidine photoproducts), and telomerase reverse transcriptase (TERT). All tumors occurred in the iris with or without ciliary body involvement and were composed of spindle cells arranged in fascicles and whorls (variable Antoni A and B behavior). All tumors were positive when immunostained for vimentin and S-100. Nine of 13 tumors exhibited GFAP immunopositivity. All tumors were negative for SMA, desmin, Melan A, and MITF-1. Tumors were variably positive for PGP 9.5, laminin, gadd45, p53, PCNA, anti-UVssDNA, and TERT. Electron microscopy revealed intermittent basal laminae between cells. These tumors are morphologically and immunohistochemically most consistent with schwannoma. The relationship between spindle cell tumors of the anterior uvea of dogs, altered neural crest, blue iris color, and ultraviolet radiation has not yet been fully elucidated.

Identification of an Immunogenic Subset of Metastatic Uveal Melanoma

PURPOSE

Uveal melanoma is a rare melanoma variant with no effective therapies once metastases develop. Although durable cancer regression can be achieved in metastatic cutaneous melanoma with immunotherapies that augment naturally existing antitumor T-cell responses, the role of these treatments for metastatic uveal melanoma remains unclear. We sought to define the relative immunogenicity of these two melanoma variants and determine whether endogenous antitumor immune responses exist against uveal melanoma.

EXPERIMENTAL DESIGN

We surgically procured liver metastases from uveal melanoma (n = 16) and cutaneous melanoma (n = 35) patients and compared the attributes of their respective tumor cell populations and their infiltrating T cells (TIL) using clinical radiology, histopathology, immune assays, and whole-exomic sequencing.

RESULTS

Despite having common melanocytic lineage, uveal melanoma and cutaneous melanoma metastases differed in their melanin content, tumor differentiation antigen expression, and somatic mutational profile. Immunologic analysis of TIL cultures expanded from these divergent forms of melanoma revealed cutaneous melanoma TIL were predominantly composed of CD8(+) T cells, whereas uveal melanoma TIL were CD4(+) dominant. Reactivity against autologous tumor was significantly greater in cutaneous melanoma TIL compared with uveal melanoma TIL. However, we identified TIL from a subset of uveal melanoma patients which had robust antitumor reactivity comparable in magnitude with cutaneous melanoma TIL. Interestingly, the absence of melanin pigmentation in the parental tumor strongly correlated with the generation of highly reactive uveal melanoma TIL.

CONCLUSIONS

The discovery of this immunogenic group of uveal melanoma metastases should prompt clinical efforts to determine whether patients who harbor these unique tumors can benefit from immunotherapies that exploit endogenous antitumor T-cell populations. Clin Cancer Res; 22(9); 2237-49. ©2015 AACR.

Infiltrating macrophages in extratumoural tissues after brachytherapy of uveal melanoma

PURPOSE

To compare distribution of macrophages in extratumoural ocular tissues in enucleated eyes with irradiated and nonirradiated uveal melanomas to find out how irradiation affects distribution of macrophages so as to gain insight into their potential routes of migration and changes in local inflammatory responses.

METHODS

Thirty-four matched pairs of primarily enucleated nonirradiated and secondarily enucleated irradiated eyes with choroidal and ciliary body melanoma were stained with mAb PG-M1, and the extratumoural immunopositive elements were counted under the microscope. Main outcome variables were the number of macrophages in the sclera underlying the tumour, in the choroid adjacent to the tumour, and in the ciliary body. The number of macrophage aggregates in the anterior ipsi- and contralateral episclera adjacent to the limbus was also counted.

RESULTS

Macrophages were more numerous within the sclera under the tumour in irradiated eyes when compared to primarily enucleated eyes (median 1514 versus 619/mm², p = 0.0001), and more aggregates of episcleral macrophages adjacent to the limbus were found after irradiation (ipsilateral side, median 132 versus 0, p = 0.0034; contralateral side, median 79 versus 0, p = 0.014). In primarily enucleated eyes, increasing numbers of tumour-infiltrating macrophages were associated with presence of higher numbers of macrophages in the ciliary body (p = 0.003) and the adjacent choroid (p = 0.044), whereas in the irradiated eyes, increasing numbers of tumour-infiltrating macrophages (p = 0.010) and increasing extent of necrosis (p < 0.001) were associated with higher numbers of intrascleral macrophages underlying the tumour.

CONCLUSIONS

Resident macrophages are present in extratumoural tissues in eyes with uveal melanoma. Brachytherapy may alter their route of migration and increase the number of macrophages in the sclera and episclera. Histopathologically detectable episcleral aggregates of macrophages adjacent to the limbus are detected predominantly after irradiation, a population of which is clinically visible as episcleral deposits after irradiation.

Uveal melanoma: the inflammatory microenvironment

Uveal melanoma is a highly malignant intraocular tumor with quite homogeneous tumor tissue and a diffuse leukocytic infiltration. In contrast with many other malignancies, the presence of infiltrating macrophages and T cells is associated with a poor prognosis rather than a good one. The clear link between inflammation and cancer in this malignancy provides a paradigm for macrophage plasticity and function. Macrophages in uveal melanoma have an M2-like phenotype and are associated with the loss of one specific chromosome - monosomy 3. The central players involved in this process and discussed in this review include macrophages, T lymphocytes, chemokines and cytokines, including the macrophage-attraction molecules. When a tumor acquires the ability to release significant amounts of macrophage-attraction molecules it causes the expansion of a population of myeloid immature cells that may not only help the tumor to suppress immune reactions but also aid in the construction of new blood vessels for tumor growth. A better understanding of the molecular basis of a local myelomonocytic cell population will bring a better understanding of the immunopathology of this disease and will lead to therapeutic interventions in uveal melanoma. This review focuses on the roles of the local inflammatory microenvironment in the development and progression of uveal melanoma.

Ipilimumab in pretreated patients with metastatic uveal melanoma: safety and clinical efficacy

Current systemic treatments for metastatic uveal melanoma (UM) have not improved overall survival (OS). The fully human anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) monoclonal antibody, ipilimumab, improved OS of patients with advanced cutaneous melanoma in a phase 3 trial; however, UM patients were excluded. The aim of this subanalysis, performed by the ipilimumab-ocular melanoma expanded access program (I-OMEAP) study group, was to assess the activity and safety of ipilimumab in patients with UM in a setting similar to daily clinical practice. Patients participating in a multicenter expanded access program (EAP) received induction treatment with ipilimumab 10 mg/kg. Maintenance doses were administered in patients who experienced clinical benefit or at physicians' discretion. Tumor assessment was evaluated per modified World Health Organization criteria at baseline, Week 12, Week 24, and Week 36. Adverse events (AEs) and immune-related AEs (irAEs) were collected according to Common Terminology Criteria for Adverse Events version 3.0. Thirteen pretreated patients with metastatic UM were treated at 6 European institutions. All patients received at least one dose of ipilimumab. Overall, no objective responses were observed; however, two patients had stable disease (SD), with a third patient achieving SD after initial progressive disease. Median OS as of July 1, 2011, was 36 weeks (range 2-172+ weeks). No grade 3/4 AEs of non-immune origin were reported. Three patients (23%) experienced grade 3 irAEs (1 thrombocytopenia, 1 diarrhea, and 1 alanine/aspartate aminotransferase elevation) that resolved with steroid therapy. The results indicate UM is a potential indication for ipilimumab treatment that should be further investigated in clinical trials.

Immunotherapy of uveal melanoma

Uveal melanoma is a malignancy with exceptional features for treatment with immunotherapy. Primary uveal melanoma can be treated with a variety of therapies that may limit the growth of the primary tumor in the eye and partially preserve vision. However, none of these treatment modalities prevents the development of metastases, which predominantly arise in the liver and universally remain fatal. Novel therapies are being explored for their effectiveness against uveal melanoma metastases and immunotherapy may be a potential option as an alternative or adjunctive treatment, even in the prophylactic setting. Uveal melanoma may be particularly responsive to T-cell-based immunotherapy because it originates in the immune-privileged eye. The localization of the primary tumor in the immune-privileged eye excuses the tumor cells from continuous immunological pressure. This may render primary uveal melanoma more immunogenic than tumor cells from non-privileged sites and allow expression of novel tumor antigens to which the patient's endogenous T cell repertoire is not tolerized. The clinical and genetic differences between cutaneous and uveal melanomas underscore the need for immunotherapy specifically designed for uveal melanoma patients. In this review, the current developments in the field of immunotherapy for uveal melanoma are discussed, with a special emphasis on T-cell-based strategies.

Changes in immunological markers and influx of macrophages following trans-scleral thermotherapy of uveal melanoma

PURPOSE

In trans-scleral thermotherapy (TSTT), heat is applied through the sclera in order to target an intraocular uveal melanoma. Previously, it had been shown that in uveal melanoma, hyperthermia and transpupillary thermotherapy influenced expression of immunologically relevant proteins, such as S100, HLA and heat-shock proteins (HSPs). We investigated whether TSTT induced similar changes.

METHODS

Experimental TSTT was applied on eleven uveal melanomas prior to enucleation. Each tumour sample was processed for histopathological examination; immunohistochemical analysis was performed to determine expression of S100, HLA, HSPs and macrophage markers.

RESULTS

In TSTT-treated areas, expression of S100 and different HSPs was lost, while an upregulated expression of HSP GP96 was observed at the border of these areas. Expression levels of HLA-A and HLA-B varied between tumours and were not influenced by TSTT. The borders of the TSTT-treated areas showed high numbers of infiltrating macrophages, which were predominantly of the M2 phenotype.

CONCLUSION

TSTT has an effect on immunological parameters with local loss of expression of HSPs and S100. The influx of M2 macrophages around the TSTT-treated areas indicates the presence of an innate immune reaction against the induced necrosis, suggesting that TSTT-treated tumour cells are removed by a macrophage-mediated tissue repair mechanism.

Immune escape mechanisms of intraocular tumors

The notion that the immune system might control the growth of tumors was suggested over 100 years ago by the eminent microbiologist Paul Ehrlich. This concept was refined and expanded by Burnet and Thomas 50 years later with their articulation of the "immune surveillance" hypothesis. In its simplest form, the immune surveillance hypothesis suggests that neoplasms arise spontaneously and express novel antigens that are recognized by the immune system, which either eliminates the tumors or restrains their growth. Within the eye, immune responses are controlled and sometimes profoundly inhibited - a condition known as immune privilege. Immune privilege in the eye is the result of a complex array of anatomical, physiological, and immunoregulatory mechanisms that prevent the induction and expression of many immune responses. Tumors arising in the eye would seem to have an advantage in evading immune surveillance due to ocular immune privilege. Uveal melanoma, the most common and malignant intraocular tumor in adults, not only benefits from the immune privilege of the eye but also has adopted many of the mechanisms that contribute to ocular immune privilege as a strategy for protecting uveal melanoma cells once they leave the sanctuary of the eye and are disseminated systemically in the form of metastases. Although the immune system possesses a battery of effector mechanisms designed to rid the body of neoplasms, tumors are capable of rapidly evolving and countering even the most sophisticated immunological effector mechanisms. To date, tumors seem to be winning this arms race, but an increased understanding of these mechanisms should provide insights for designing immunotherapy that was envisioned over half a century ago, but has failed to materialize to date.

A role for EZH2 in silencing of IFN-gamma inducible MHC2TA transcription in uveal melanoma

We investigated the contribution of epigenetic mechanisms in MHC2TA transcriptional silencing in uveal melanoma. Although no correlation was observed between impaired CIITA transcript levels after IFN-gamma induction and DNA methylation of MHC2TA promoter IV (CIITA-PIV), an association was found with high levels of trimethylated histone H3-lysine 27 (3Me-K27-H3) in CIITA-PIV chromatin. The 3Me-K27-H3 modification correlated with a strong reduction in RNA polymerase II-recruitment to CIITA-PIV. Interestingly, we observed that none of these epigenetic modifications affected recruitment of activating transcription factors to this promoter. Subsequently, we demonstrated the presence of the histone methyltransferase EZH2 in CIITA-PIV chromatin, which is known to be a component of the Polycomb repressive complex 2 and able to triple methylate histone H3-lysine 27. RNA interference-mediated down-regulation of EZH2 expression resulted in an increase in CIITA transcript levels after IFN-gamma induction. Our data therefore reveal that EZH2 contributes to silencing of IFN-gamma-inducible transcription of MHC2TA in uveal melanoma cells.

Uveal melanoma expression of indoleamine 2,3-deoxygenase: establishment of an immune privileged environment by tryptophan depletion

The enzyme indoleamine 2,3-dioxygenase (IDO) catalyzes degradation of tryptophan, an essential amino acid required for lymphocyte activation and proliferation. Many tumors express IDO which implies that it acts as a mechanism to evade T cell-mediated immune attack, and also to establish an immunosuppressive tumor microenvironment. The purpose of this study was to determine whether primary and metastatic uveal melanoma expressed the IDO gene and whether uveal melanoma cells could deplete tryptophan. In situ expression of IDO in primary uveal melanoma from tumor bearing eyes and metastatic uveal melanoma liver tissues was determined by immunohistostaining with IDO-specific antibody. Reverse transcription PCR was used to assess IDO gene transcription by primary and metastatic uveal melanoma cell lines. IDO protein expression was determined by Western blot of uveal melanoma cell protein lysate. IDO catalytic activity was assessed by measuring the presence of kynurenine, a product generated by tryptophan degradation, in uveal melanoma culture supernatants. Primary uveal melanoma from tumor-bearing eyes and metastatic uveal melanoma from the liver did not express IDO in situ. IDO was not constitutively expressed in either primary or metastatic uveal melanoma cell lines. However, stimulation of primary and metastatic uveal melanoma cell cultures with interferon-gamma (IFN-gamma) universally upregulated both IDO gene and protein expression. Culture supernatants from IFN-gamma treated primary and metastatic uveal melanoma cell cultures contained elevated levels of kynurenine. Addition of the IDO inhibitor 1-methyl dl-tryptophan significantly diminished kynurenine levels in IFN-gamma treated uveal melanoma cell cultures. The results from this study suggest that IFN-gamma inducible IDO upregulation by primary and metastatic uveal melanoma may generate a local immune privileged microenvironment to promote escape from T cell-mediated immune surveillance.

Presence and phenotype of dendritic cells in uveal melanoma

BACKGROUND

Uveal melanoma arises in an immune-privileged site and can itself add to the immunosuppressive environment. Previous studies on cutaneous melanoma have shown the presence of tolerogenic dendritic cells (DCs), which could play an important role in the progression of the tumour.

AIM

To examine the presence and functional status of DCs in a small series of uveal melanomas.

METHODS

10 cases of uveal melanoma were examined for the expression of FXIIIa, CD68, human leucocyte antigen (HLA)-DR, CD40, CD83, transforming growth factor betaR1 and indolamine 2,3 dioxygenase by immunohistochemical analysis on sections embedded in paraffin wax.

RESULTS

CD68-positive macrophages were present in all of the tumours and were evenly distributed throughout. DCs expressing FXIIIa-positive were seen in 7 cases, and were often found concentrated in foci within the tumour mass. These cells were dendritic and expressed high levels of HLA-DR. The DCs did not express the maturation markers CD83 or CD40. In one case, concentration of DCs around the area of tumour necrosis was observed, and some of these cells expressed CD83.

CONCLUSION

Numerous tolerising antigen-presenting cells may play a role in melanoma-related immunosuppression in the eye, although activation of DCs may be associated with tumour necrosis.

MHC class II-transduced tumor cells originating in the immune-privileged eye prime and boost CD4(+) T lymphocytes that cross-react with primary and metastatic uveal melanoma cells

Uveal melanoma, the most common malignancy of the eye, has a 50% rate of liver metastases among patients with large primary tumors. Several therapies prolong survival of metastatic patients; however, none are curative and no patients survive. Therefore, we are exploring immunotherapy as an alternative or adjunctive treatment. Uveal melanoma may be particularly appropriate for immunotherapy because primary tumors arise in an immune-privileged site and may express antigens to which the host is not tolerized. We are developing MHC class II (MHC II)-matched allogeneic, cell-based uveal melanoma vaccines that activate CD4(+) T lymphocytes, which are key cells for optimizing CD8(+) T-cell immunity, facilitating immune memory, and preventing tolerance. Our previous studies showed that tumor cells genetically modified to express costimulatory and MHC II molecules syngeneic to the recipient are potent inducers of antitumor immunity. Because the MHC II-matched allogeneic vaccines do not express the accessory molecule, Invariant chain, they present MHC II-restricted peptides derived from endogenously encoded tumor antigens. We now report that MHC II-matched allogeneic vaccines, prepared from primary uveal melanomas that arise in the immune-privileged eye, prime and boost IFNgamma-secreting CD4(+) T cells from the peripheral blood of either healthy donors or uveal melanoma patients that cross-react with primary uveal melanomas from other patients and metastatic tumors. In contrast, vaccines prepared from metastatic cells in the liver are less effective at activating CD4(+) T cells, suggesting that tumor cells originating in immune-privileged sites may have enhanced capacity for inducing antitumor immunity and for serving as immunotherapeutic agents.

Immunophenotypic markers to differentiate between benign and malignant melanocytic lesions

BACKGROUND/AIMS

The authors investigated the expression of S100A1, S100A6, S100B, MelanA, and CEA in conjunctival naevi, primary acquired melanosis (PAM), conjunctival melanoma, and uveal melanoma in order to assess their potential usefulness in the pathological differential diagnosis of these entities.

METHODS

Paraffin embedded sections of 18 conjunctival naevi, 14 PAM, 16 conjunctival melanomas, and 20 uveal melanomas were immunostained for S100A1, S100A6, S100B, MelanA, and CEA, and expression was scored semiquantitatively.

RESULTS

Expression of S100A1 differed significantly between conjunctival naevi and conjunctival melanoma, with percentages of positive cells of 30.6% and 71.4%, respectively. Conjunctival melanomas had high average scores for S100A1 and S100B (71.4%, 62.9%, respectively), while uveal melanomas also had high S100A1 but low S100B scores (88.5%, 18.5%, respectively). MelanA was highly variable; naevi and uveal melanoma had higher average scores than conjunctival melanoma. CEA was hardly detectable in all four groups.

CONCLUSION

S100A1 seems to be a possible candidate to differentiate conjunctival naevi from conjunctival melanoma. S100B seems to differentiate between uveal melanoma and conjunctival melanoma. However, the study size was small and therefore the data have to be confirmed by others.

alpha-Melanocyte stimulating hormone, inflammation and human melanoma

Alpha-melanocyte stimulating hormone (alpha-MSH) arises from the proteolytic cleavage of proopiomelanocortin (POMC) and is the most potent naturally occurring melanotropic peptide. The biological effects of alpha-MSH are mediated via melanocortin receptors (MCRs), which are expressed in virtually every cutaneous cell type. alpha-MSH has pleiotrophic functions including the modulation of a wide range of inflammatory stimuli such as proinflammatory cytokines, adhesion molecules and inflammatory transcription factors. All of the former would be consistent with a cytoprotective role for this hormone in protecting skin cells from exogenous stress, as would occur following UV exposure or exposure to agents inducing inflammation or oxidative stress. In addition to actions on normal skin cells it also modulates both cutaneous and uveal melanoma cell behavior. With respect to melanoma, alpha-MSH is intriguing as studies have shown that while alpha-MSH has the potential to retard metastatic spread (by reducing cell migration and invasion) it is also capable of reducing the ability of the immune system to detect tumor cells (by down regulating adhesion molecules that would normally assist in immune cell interaction with melanoma cells). This review considers the evolving biology of alpha-MSH and discusses its role in man that extend far beyond pigmentation of skin melanocytes, suggesting that the detoxifying role of alpha-MSH in inducing melanogenesis is only one aspect of the stress-coping role of this hormone. Indeed melanoma cells may owe at least some of their success to the 'protective' role of alpha-MSH.

Tumor infiltrating lymphocytes in uveal melanoma: a link with clinical behavior?

Experimental and clinical evidence indicate that immunological mechanisms might be important in the clinical course of uveal malignant melanoma (UMM). We analyzed the amount and phenotype of tumor infiltrating lymphocytes (TIL) and the expression of the apoptosis-inducing molecule Fas and its ligand, FasL, on tumor cells and TIL in a selected series of UMM with the aim to establish if a correlation between their expression and the clinical behavior of UMM exists. TIL phenotype and Fas/FasL expression were evaluated by immunohistochemistry in 61 cases of formalin-fixed, paraffin-embedded UMM. Results were compared with the follow-up data of patients. Most of the UMM showed a prevalence of CD8+ CD3+ T lymphocytes, or CD4+ and CD8+ cells in equal amounts. UMM showed a variable expression of FasL, ranging from 0 to > 40% of neoplastic cells. Fas was always expressed in TIL, although with a variable extent. A subgroup of UMM showed in TIL a strongly reduced or even absent expression of TCR zeta-chain, involved in activation of T-lymphocytes. This subgroup was characterized by a worse outcome. We hypothesized that an impaired cytotoxic immune response due to the loss of the zeta-chain expression plays a primary role in the biological course of UMM. Our results indicate that the overcoming of the impairment of TCR function may represent a prerequisite for the development of new therapeutic strategies for managing UMM, suggesting that elimination of tumor cells may be possible by activation of cytotoxic cells present within ocular melanomas.

In Vitro Targeting of NG2 Antigen by213Bi-9.2.27 α-Immunoconjugate Induces Cytotoxicity in Human Uveal Melanoma Cells

PURPOSE

To examine uveal melanoma cell lines for the expression of human melanoma proteoglycan (NG2) using monoclonal antibody (mAb) 9.2.27 and subsequently to assess the in vitro specificity and cytotoxicity of mAb 9.2.27 conjugated to the alpha-particle-emitting radioisotope 213bismuth (213Bi-9.2.27) for uveal melanoma cells.

METHODS

Immunocytochemistry and flow cytometry were used to examine OCM-1, OCM-3, OCM-8, OMM-1, Mel202 and 92-1 melanoma cell lines for NG2 expression. Melanoma cells were treated with test (213Bi-9.2.27) or control (213Bi-A2) alpha-immunoconjugates (AICs). The specific cytotoxicity of 213Bi-9.2.27 AIC was evaluated using an MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfenyl)-2H-tetrazolium, inner salt) assay. Cell death was also assessed using TUNEL.

RESULTS

OCM-1, OCM-8, OMM-1, and Mel202 cells strongly expressed NG2. OCM-3 cells showed moderate expression and 92-1 cells were NG2-negative. 213Bi-9.2.27 specifically killed NG2-positive OCM-1, OCM-8, and OMM-1 cells in a concentration-dependent manner. D0 values for 37% cell survival of NG2-positive OCM-1, OCM-8, and OMM-1 cells were 5.8, 5.0, and 5.6 microCi, respectively, and the value was 43.4 muCi for NG2-negative 92-1 cells.

CONCLUSIONS

The specific cytotoxicity of 213Bi-9.2.27 AIC for NG2-positive, but not NG2-negative, cells suggests NG2 is a suitable target for alpha-immunotherapy in uveal melanoma. 213Bi-9.2.27 AIC used directly or as adjunct therapy may be a promising new agent for treating NG2-positive uveal melanomas or metastases.

Effect of an anti-CD54 (ICAM-1) monoclonal antibody (UV3) on the growth of human uveal melanoma cells transplanted heterotopically and orthotopically in SCID mice

We have shown that administration of a novel anti-CD54 monoclonal antibody (UV3) results in long-term survival of SCID mice bearing human myeloma xenografts. Previous studies have demonstrated a link between the expression of CD54 and the progression of uveal melanoma. Our study assessed the expression of CD54 on 7 human uveal melanoma cell lines and 3 cell lines established from uveal melanoma metastases. In vivo studies examined the efficacy of systemic and local administration of UV3 antibody on the progression of uveal melanoma cells transplanted either heterotopically or orthotopically into SCID mice. Five of the 7 primary uveal melanoma cell lines and all 3 of the metastases cell lines expressed CD54. Intraperitoneal injection of either IgG or F(ab')2 fragments of UV3 significantly inhibited the growth of subcutaneous and intraocular melanomas. Subconjunctival injection of either IgG or F(ab')2 fragments of UV3 produced a significant reduction in the growth of intraocular melanomas, even if the antibody was administered after the appearance of intraocular tumors. The results indicate that both primary and metastatic human uveal melanoma cells express CD54. The marked inhibition of intraocular and subcutaneous uveal melanoma progression suggests that UV3 antibody is a promising therapeutic agent for further evaluation in patients with uveal melanoma. This is especially noteworthy, as no existing therapeutic modality prevents metastasis of uveal melanoma or prolongs the survival of patients with uveal melanoma.

Immunology of intraocular tumors

The immune surveillance hypothesis was introduced over 30 years ago and proposed that neoplasms express novel antigens that subjected them to immune detection and elimination. In order for immune surveillance to be effective in controlling neoplasms, two requirements must be satisfied: 1) the tumor must arise in a body site that permits the induction the full array of immune responses and 2) the immune elements generated must have unfettered access to the tumor and be able to express their entire range of effector functions at the tumor site. The unique immunologic and anatomic features of the eye prevent the induction and expression of conventional immunity--a phenomenon known as 'immune privilege'. Although ocular immune privilege represents a theoretical obstacle to immune surveillance, some highly immunogenic intraocular tumors can circumvent immune privilege and undergo immune rejection. Uveal melanoma is the most common intraocular malignancy in adults, yet it occurs with a frequency that is no higher than neoplasms arising in conventional bodies. The presence of either tumor-infiltrating lymphocytes (TIL) or tumor-infiltrating macrophages (TIM) is associated with poor prognosis in uveal melanoma patients and suggests that some immune responses to intraocular tumors might exacerbate, rather than mitigate, tumor progression. Although counterintuitive, this proposition is consistent with the 'immune stimulation' hypothesis of tumor progression offered by Richmond Prehn over thirty years ago. It remains to be ascertained if immune stimulation affects the malignancy of ocular tumors, but it represents an intriguing explanation for the paradoxes of uveal melanoma.

Expression and Possible Function of IL-2 and IL-15 Receptors on Human Uveal Melanoma Cells

PURPOSE

Interleukin-2 (IL-2) and IL-15 receptors have been detected on some murine neoplasms. Accordingly, the expression of these receptors on human uveal melanoma cell lines was examined, and the effect of exogenous IL-2 and -15 on melanoma cell proliferation, susceptibility to natural killer (NK) cell-mediated cytolysis, and sensitivity to apoptosis were assessed.

METHODS

Nine human uveal melanoma cell lines and three cell lines from uveal melanoma metastases were tested by flow cytometry for the expression of human IL-2R and -15Ralpha. Melanoma cells were cultured, with or without recombinant human IL-2 or -15, cell proliferation was determined by tritiated thymidine incorporation, and IL-2 and -15 receptor expression was assessed by flow cytometry. The effect of these cytokines on NK activity was evaluated with a standard (51)Cr-release assay.

RESULTS

All the melanoma cell lines expressed IL-2R and -15R. IL-2 induced a three- to eightfold upregulation of IL-2R expression in all the melanoma cell lines. Although IL-2 did not affect the proliferation of six of the seven uveal melanoma cell lines, it induced a 32% and 57% increase in the proliferation of both metastatic cell lines. IL-15 induced proliferation on all tested cell lines (4%-68%). Both IL-2 and -15 reduced melanoma cell sensitivity to NK-cell-mediated cytolysis and cisplatin-induced apoptosis.

CONCLUSIONS

The results suggest that IL-2 and -15 elaborated by tumor-infiltrating lymphocytes and macrophages may affect the malignant behavior of human uveal melanoma by stimulating proliferation and reducing uveal melanoma cell susceptibility to NK-cell-mediated cytolysis and cisplatin-induced apoptosis.

Autocrine secretion of Fas ligand shields tumor cells from Fas-mediated killing by cytotoxic lymphocytes

Mechanisms responsible for resistance of tumors to death receptor-mediated damage by cytotoxic lymphocytes are not well understood. Uveal melanoma cells expressed Fas but were insensitive to Fas triggering induced by bystander cytotoxic T lymphocytes or a Fas-specific agonistic antibody; this could not be ascribed to tumor counterattack against T cells or general resistance of the tumors to apoptosis. Treatment with inhibitors of metalloproteases rendered uveal melanomas sensitive to Fas-mediated cytotoxicity. Metalloprotease inhibitors did not affect the expression of Fas but increased the surface expression of Fas ligand (FasL), which correlated with the disappearance of soluble FasL from culture supernatants of tumor cells. FasL eluted from the surface of uveal melanomas specifically inhibited cytotoxic T lymphocyte lysis of tumor cells pretreated with an inhibitor of metalloproteases. In addition to uveal melanomas, a number of other tumor cell lines of various cellular origins were sensitized to Fas-mediated cytotoxicity by metalloprotease inhibitors. Our results show that autocrine secretion of FasL shields tumor cells from Fas-mediated killing by cytotoxic lymphocytes. This defines a novel mechanism of tumor escape from immune surveillance.

Interferon alpha 2b decreases hepatic micrometastasis in a murine model of ocular melanoma by activation of intrinsic hepatic natural killer cells

PURPOSE

To investigate in a murine model the mechanism by which micrometastatic melanoma, which spreads from the eye to the liver, is controlled by interferon (IFN)-alpha 2b.

METHODS

Major histocompatibility (MHC) class I antigen (H-2, all haplotypes) expression in three murine melanoma cell lines (Queens, B16LS9, B16F10) was determined by flow cytometric immunophenotyping. The cell lines were heterotopically inoculated into the posterior compartments (PCs) of C57Bl/6 mice, and the mice were given intraperitoneal (IP) injections of IFN-alpha 2b or PBS for 1 or 4 days before enucleation at 7 days after inoculation. Groups of mice were made NK deficient or depleted with subcutaneous (s.c.) injection of anti-asialo GM1. The mice were killed at 28 days or 56 days (survival experiment) after inoculation, and the number of hepatic micrometastases was histologically determined. NK cells were isolated from the spleen and liver at necropsy, and propidium iodide labeled target-specific cytolysis was determined by flow cytometry. The micrometastases were evaluated for apoptosis and proliferation with TUNEL and MIB1 immunostaining, respectively, and TUNEL-to-MIB1 ratios were determined. Hepatic NK cells were immunostained with CD49b.

RESULTS

MHC class I antigen was expressed in the three cell lines in the order of Queens < B16LS9 < B16F10. All cell lines grew, were confined to the PC, and formed hepatic micrometastases. A decrease in micrometastases, an increase in target-specific cytolysis, and an increase in survival correlated with decreased HLA class I expression by the melanoma cells. The IFN-alpha 2b treatment resulted in a boost of intrinsic hepatic NK cells, demonstrated in NK-deficient but not NK-depleted mice. The treatment effect corresponded to increased apoptosis (TUNEL)-proliferation (MIB1) ratios in the micrometastases. Immunostaining demonstrated an increased number of intrahepatic NK cells associated with the micrometastases in treated groups.

CONCLUSIONS

Neoadjuvant IFN-alpha 2b results in decreased hepatic micrometastasis and increased survival time through increased intrinsic hepatic NK cell-mediated tumor apoptosis in a murine model of metastatic ocular melanoma.

Evidence of macrophage and lymphocyte, but not dendritic cell, infiltration in posterior uveal melanomas, whilst cultured uveal melanomas demonstrate pluripotency by expressing CD68 and CD163

Although variation in the level of macrophage infiltration has been reported in uveal melanoma, little is known about the expression of other leucocyte markers. An immuno- histochemistry study of the levels of expression of macrophage and other leucocyte markers, in a series of 10 primary choroidal melanoma biopsies, was undertaken. Biopsies were either fixed immediately in formalin and embedded in paraffin wax or established as short-term cultures. Using single- and double-labelling immunohistochemistry, cultured cells and paraffin sections were analysed for a range of melanoma (HMB45, Melan A, S100 and tyrosinase) and immune cell (CD68, CD163, CD45 and CD1a) markers. All samples expressed at least two known melanoma markers. Infiltrating macrophages were present in the majority of sections. When cultured specimens were studied by double-labelling immunofluorescence, uveal melanoma cells were seen to express macrophage markers or have cross-reactivity with related proteins. Expression of the leucocyte antigen CD45 was observed in three tumours but was not present in any cultured cells, whilst the expression of the dendritic cell marker CD1a was absent from all samples.

Simultaneous CD8+ T cell responses to multiple tumor antigen epitopes in a multipeptide melanoma vaccine

The recent identification and molecular characterization of tumor-associated antigens recognized by tumor-reactive CD8+ T lymphocytes has led to the development of antigen-specific immunotherapy of cancer. Among other approaches, clinical studies have been initiated to assess the in vivo immunogenicity of tumor antigen-derived peptides in cancer patients. In this study, we have analyzed the CD8+ T cell response of an ocular melanoma patient to a vaccine composed of four different tumor antigen-derived peptides administered simultaneously in incomplete Freund's adjuvant (IFA). Peptide NY-ESO-1(157-165) was remarkably immunogenic and induced a CD8+ T cell response detectable ex vivo at an early time point of the vaccination protocol. A CD8+ T cell response to the peptide analog Melan-A(26-35 A27L) was also detectable ex vivo at a later time point, whereas CD8+ T cells specific for peptide tyrosinase(368-376) were detected only after in vitro peptide stimulation. No detectable CD8+ T cell response to peptide gp100(457-466) was observed. Vaccine-induced CD8+ T cell responses declined rapidly after the initial response but increased again after further peptide injections. In addition, tumor antigen-specific CD8+ T cells were isolated from a vaccine injection site biopsy sample. Importantly, vaccine-induced CD8+ T cells specifically lysed tumor cells expressing the corresponding antigen. Together, these data demonstrate that simultaneous immunization with multiple tumor antigen-derived peptides can result in the elicitation of multiepitope-directed CD8+ T cell responses that are reactive against antigen-expressing tumors and able to infiltrate antigen-containing peripheral sites.

Major histocompatibility antigens and antigen-processing molecules in uveal melanoma

PURPOSE

Malignant transformation of cells is frequently associated with abnormalities in the human leukocyte antigen (HLA) expression. These abnormalities may play a role in the clinical course of the disease, because HLA antigens mediate interactions of tumor cells with T cells and natural killer cells. Uveal melanoma is a highly malignant tumor of the eye and is characterized by hematogenic spread to liver. Antigen-processing molecules (APMs) are necessary for efficient expression of HLA class I antigens. We studied the expression of HLA antigens and the APM in uveal melanomas by immunohistochemistry and correlated clinicopathologically.

EXPERIMENTAL DESIGN

HLA class I antigen, beta(2)-microglobulin (beta(2)-m), HLA class II antigens, and the APM comprising proteasomal subunits low molecular mass polypeptide (LMP) 2, beta-subunit of LMP2-Delta, LMP 10, transporter associated protein 1 subunit, and chaperone molecules tapasin and calnexin were studied in 41 primary uveal melanoma archival specimens by immunohistochemistry. Immunoanalysis was done by a semiquantitative method and correlated with extrascleral extension, cell types, and the largest tumor diameter.

RESULTS

HLA class I antigen, beta(2)-m, HLA class II antigen, and the APM were decreased (negative staining in 29 tumors and dull staining in 3 tumors) in 100% (32 of 32) uveal melanomas with no extrascleral extension. (P = 0.01) and positive (bright staining) in 67% (4 of 9) tumors with liver metastasis. Decreased immunoexpression of HLA antigens and the APM was seen in nonepithelioid cell melanomas. There was no correlation with largest tumor diameter.

CONCLUSIONS

Our data suggest decreased expression of HLA, and APM are seen in uveal melanomas with no extrascleral extension and in nonepithelioid cell melanomas. Decreased expression of APM may contribute to decreased HLA class I antigen expression.

Localization and characterization of melanoma-associated glycosaminoglycans: differential expression of chondroitin and heparan sulfate epitopes in melanoma

Glycosaminoglycans (GAGs) are anionic polysaccharides present on cells and in the extracellular matrix (ECM). They likely play a role in tumor formation because of their capacity to bind and modulate a variety of proteins including growth factors, cytokines, and proteases. Using a panel of (human) phage display-derived anti-GAG antibodies, the location and expression of GAG epitopes in human cutaneous melanocytic lesions was studied. Antibodies EW4E1 and EW4G2 identified a melanoma-associated chondroitin sulfate/heparan sulfate epitope, whereas antibody EW4B7 recognized a melanoma-associated heparan sulfate epitope. These antibodies showed a high reactivity with blood vessels and ECM in cutaneous melanoma tumors, whereas their reactivity with nevi was very low. Using a set of defined oligosaccharides it was established that sulfate groups are of main importance in the binding to the antibodies and that glycomimetics can mimic natural oligosaccharides. In xenografts of melanoma cell line MeL57, a strong association of GAG epitopes with an injected fluorescent fluid flow tracer was observed. In uveal melanoma antibody, EW4E1 proved to be a sensitive probe for the detection of the geometry of ECM structures, known to have prognostic value. Taken together, data indicate that in melanoma a defined set and location of GAG epitopes are present with possible functional significance.

Human uveal melanoma expresses NG2 immunoreactivity

BACKGROUND/AIMS

NG2 is the rat homologue of the human melanoma proteoglycan (HMP), also known as the high molecular weight melanoma associated antigen. Most cutaneous melanomas, as well as glioblastomas, chondrosarcomas, and some leukaemias express NG2 immunoreactivity, recognised using monoclonal antibody (mAb) 9.2.27. This antibody has also been used for molecular targeting in targeted alpha therapy for melanoma. The purpose of this study was to evaluate the expression of NG2 immunoreactivity in human uveal melanoma and normal ocular tissue using mAb 9.2.27.

METHODS

Enucleated eyes from 26 patients with choroidal or ciliary body melanoma (n=26) were available as paraffin sections, and stained with haematoxylin and eosin to assess for tumour cell type and histopathology. Additional slides were investigated for NG2 immunoreactivity using mAb 9.2.27 and alkaline phosphatase anti-alkaline phosphatase (APAAP) immunostaining. Two independent observers graded immunostaining using a semiquantitative scale from 0 (negative) to 3 (strong).

RESULTS

Immunostaining for mAb 9.2.27 could not be graded in 7/26 cases with dense pigmentation of the tumour. For the remaining cases, grade 2 (moderate) or more immunostaining was seen in 18/19 tumours (95%). The retina, retinal pigment epithelium (RPE), and choroid displayed weak immunostaining (grade 0.5-1.5) in the majority of melanoma affected eyes. Normal retina and choroid (n=5) appeared negative for mAb 9.2.27. Optic nerve axon bundles in both control and melanoma affected eyes displayed moderate immunostaining.

CONCLUSION

In the present study, the majority of human uveal melanomas expressed NG2 immunoreactivity, as detected using mAb 9.2.27. This antibody may be a suitable candidate for radioimmunotherapy to target ocular melanoma.

Expression of classic and nonclassic HLA class I antigens in uveal melanoma

PURPOSE

Because the expression of classic and nonclassic HLA antigens is crucial for the recognition and elimination of tumor cells by cytotoxic T and/or NK cells, we analyzed the HLA-A, -B, -C, and -G expression in uveal melanoma specimens from 18 patients.

METHODS

Tumor specimens and EDTA plasma samples from 18 patients treated by primary enucleation or tumor resection for primary uveal melanoma in the University Eye Clinic, Essen, Germany, were collected immediate after surgery. After solubilization of tumor tissue and specific immunoprecipitation of classic HLA-A, -B, and -C and nonclassic HLA-G antigens the tumor samples were analyzed by one-dimensional isoelectric focusing (1D-IEF) and Western blot analysis. In parallel, patients were typed for HLA-A, -B, and -C class I antigens by PCR with sequence-specific primers (PCR-SSP). In addition, HLA-A2 and -G expression was investigated by immunohistochemistry in paraffin-embedded tumor sections from these patients.

RESULTS

In 9 (50%) of 18 specimens, a full HLA-A and -B antigen expression pattern was detected by 1D-IEF. In six (33.3%) tumor specimens, an HLA class I allotype was missing (HLA-A2, -A28, -A29, -B18, -B35, and -B55), in two cases a haplotypic loss (HLA-A2, -B44 and HLA-A2, -B13) and in another case an allotype-specific loss combined with a haplotypic loss (HLA-A26, -A32, -B41) were observed. HLA-C and -G antigens were not detectable in any of the tumor samples by biochemical methods used.

CONCLUSIONS

A considerable portion of the uveal melanomas tested showed a loss of classic HLA class I antigens, which may enable them to escape from the immunosurveillance of cytotoxic T cells. HLA-C and -G antigens were not found in uveal melanoma tissue implying a susceptibility for NK lysis.

Apoptotic cell death in conjunction with CD80 costimulation confers uveal melanoma cells with the ability to induce immune responses

Uveal melanoma is a rare malignancy with a poor prognosis despite current therapeutic intervention. The current investigation focuses on the immunogenicity of uveal melanoma cells genetically modified with recombinant adenovirus encoding CD80 (AdCD80) in contrast to their parental counterpart. We demonstrate that costimulation provided by uveal melanoma cells improved immune responses in vitro as determined by mixed lymphocyte tumour cell cultures and cytotoxic T-cell assays using lymphocytes from healthy donors and uveal melanoma patients. Flow cytometry revealed T-cell stimulation by activated CD4+ and CD8+ T cells. Additionally, autologous lymphocytes proliferated in response to CD80-expressing primary uveal melanomas, indicating that this patient group is suitable for immunotherapy. Moreover, this study utilized AdCD80 modified and parental apoptotic tumour cells, loaded onto immature dendritic cells, as a source of tumour antigen. The ability of live or apoptotic tumour cells to stimulate lymphocyte proliferation and activation was determined. Apoptotic uveal melanoma cells expressing CD80 were efficient at inducing an immune response and served as a potent immunogen. The use of apoptotic uveal melanoma cells in combination with expression of costimulatory molecules could prove a novel adjuvant therapy for the treatment of this disease.

The need for continuous immunosuppression with cyclosporin A to maintain an experimental model of uveal melanoma

We investigated the need for continuous immunosuppression to maintain experimental tumours derived from human uveal melanoma cells implanted in the choroid of pigmented rabbits. Two groups of pigmented rabbits immunosuppressed with cyclosporin A (CsA) were implanted with human uveal melanoma cells in the suprachoroidal space. After 5 weeks, CsA was discontinued in group 2. Animals were treated with prophylactic antibiotics and examined weekly for tumour growth, weight and secondary effects; blood urea nitrogen levels were measured every two weeks. Autopsies and histopathological studies were performed after death or euthanasia at the end of week 12. The difference between the groups in the development of ophthalmoscopic tumours was not statistically significant 5 weeks after implantation. Tumours in group 1 grew progressively throughout the experiment, whereas group 2 tumours showed marked regression 3-4 weeks after discontinuing CsA. Tumours in group 1 were significantly larger and had greater mitotic activity and showed more ciliary body, optic nerve and extrascleral invasion than tumours in group 2, which showed massive fibrosis, minimal mitotic activity and marked inflammatory cell infiltration. Continuous immunosuppression with CsA seems to be necessary to maintain tumour growth in this experimental model of uveal melanoma.

HLA expression in uveal melanoma: there is no rule without some exception

A decrease in the expression of HLA antigens is considered a characteristic of tumor progression and is considered an important tumor-escape mechanism. In general, HLA Class I expression is even further decreased on metastases. Tumor cells that loose their HLA Class I antigens become less susceptible to lysis by specific T cells, but may become more sensitive to Natural Killer cells. Loss of HLA Class I can be observed at different levels, i.e. total loss of Class I, loss of expression of one locus or one haplotype, or even one specific allele. We studied HLA expression on human uveal melanoma and observed that loss of expression of a locus or one or more alleles is a common phenomenon. However, in contrast with the commonly accepted paradigm, loss of HLA Class I expression on the uveal melanoma was not associated with tumor cell escape and a worse survival, but with a better survival of the patients involved. We hypothesize that this is due to the route of metastases formation: in uveal melanoma, spreading of metastases is purely hematogeneous, and it is quite possible that NK-cell mediated surveillance of tumor cells in the blood is the underlying mechanism. This is supported by our finding that metastases of uveal melanoma have a high HLA Class I expression, leading to our conclusion that uveal melanoma is an exception to the general rule regarding HLA Class I expression in tumor immunology.