Uveal melanoma

Uveal melanoma, which arises from melanocytes residing in the stroma, is the most common primary intraocular tumor in adults. Up to 50% of patients with primary uveal melanoma will ultimately develop distant metastasis, the liver being involved in up to 90% of individuals and the median survival reported to be 4-5 months. The current treatment of metastatic uveal melanoma is limited by the lack of effective systemic therapy. The intrinsic resistance of uveal melanoma to conventional systemic chemotherapy has led researchers to evaluate new approaches. Molecular biology and a better knowledge of cancer cells allowed the development of target therapies: these refer to drugs designed to interact with a specific molecular pathway known to have a critical role in tumor growth or progression. Several drugs, such as bevacizumab, imatinib and MEK-inhibitors, are currently under investigation as single agents or in combination with chemotherapeutic drugs for the treatment of metastatic uveal melanoma. Finally, ipilimumab, which targets the immune compartment, was reported to increase overall survival in cutaneous melanoma patients, with preliminary evidence of similar activity in ocular melanoma.     

New therapeutic agents in uveal melanoma

Uveal melanoma is the most common primary intraocular malignant tumour in adults. Five, ten and fifteen years after primary tumour treatment, up to 25%, 34% and 50% of patients may develop metastases, respectively. There are only a few systemic therapies that have been approved for uveal melanoma, all with doubtful efficacy. As the molecular knowledge over cancer has improved, new therapies are being developed. Several drugs, such as bortezomib, celecoxib, dacarbazine, anti-angiogenic agents (such as bevacizumab, sorafenib and sunitinib), temsirolimus, mitogen-activated protein kinase kinase (MEK) inhibitors, ipilimumab and AEB071 are candidate drugs, and studies are underway to determine the therapeutic effects of these drugs in uveal melanoma.     

Uveal melanoma: From diagnosis to treatment and the science in between

Melanomas of the choroid, ciliary body, and iris of the eye are collectively known as uveal melanomas. These cancers represent 5% of all melanoma diagnoses in the United States, and their age‐adjusted risk is 5 per 1 million population. These less frequent melanomas are dissimilar to their more common cutaneous melanoma relative, with differing risk factors, primary treatment, anatomic spread, molecular changes, and responses to systemic therapy. Once uveal melanoma becomes metastatic, therapy options are limited and are often extrapolated from cutaneous melanoma therapies despite the routine exclusion of patients with uveal melanoma from clinical trials. Clinical trials directed at uveal melanoma have been completed or are in progress, and data from these well designed investigations will help guide future directions in this orphan disease. Cancer 2016;122:2299–2312 . © 2016 American Cancer Society.     

Evaluation of oncogenic cysteinyl leukotriene receptor 2 as a therapeutic target for uveal melanoma

Uveal melanoma is a rare, but deadly, form of eye cancer that arises from melanocytes within the uveal tract. Although advances have emerged in treatment of the primary tumour, patients are still faced with vision loss, eye enucleation and lethal metastatic spread of the disease. Approximately 50% of uveal melanoma patients develop metastases, which occur most frequently in the liver. Metastatic patients encounter an extremely poor prognosis; as few as 8% survive beyond 2 years. Understanding of the genetic underpinnings of this fatal disease evolved in recent years with the identification of new oncogenic mutations that drive uveal melanoma pathogenesis. Despite this progress, the lack of successful therapies or a proven standard-of-care for uveal melanoma highlights the need for new targeted therapies. This review focuses on the recently identified CYSLTR2 oncogenic mutation in uveal melanoma. Here, we evaluate the current status of uveal melanoma and investigate how to better understand the role of this CYSLTR2 mutation in the disease and implications for patients harbouring this mutation.     

Molecular pathways mediating liver metastasis in patients with uveal melanoma

Uveal melanoma arises from melanocytes located in the uveal tract of the eye and is the most common primary intraocular tumor in adults. Metastatic liver disease is the overwhelming cause of death in uveal melanoma patients, with almost 50% of patients developing liver metastases up to 15 years after diagnosis. Most of these patients do not present with any evidence of overt metastasis at the time of initial diagnosis although it is assumed that they have undetectable micrometastases. Currently, there are no therapeutic modalities to prevent or efficiently treat the metastatic disease in uveal melanoma patients. Recent discoveries have shed light on the molecular pathways that may contribute to the progression of liver metastasis. The aim of this review is to describe new insights into the genetic and molecular pathways that may play a role in the development of liver metastases in uveal melanoma patients.     

The insulin-like growth factor-I receptor inhibitor picropodophyllin causes tumor regression and attenuates mechanisms involved in invasion of uveal melanoma cells.

PURPOSE: Uveal melanoma has a high mortality rate due to a high incidence of metastasis (up to 50%), which preferentially occurs in the liver. Conventional chemotherapy, being the only therapeutic option today against metastatic uveal melanoma, has not proved to be effective. Therefore, new molecular targets important for malignant phenotype of uveal melanoma have to be found to design efficient pharmacologic agents. EXPERIMENTAL DESIGN: We previously reported data indicating that the insulin-like growth factor-1 receptor (IGF-IR) is a metastasis predictor as well as a therapeutic target for uveal melanoma. In the present study, we made use of the cyclolignan picropodophyllin (PPP), which is an inhibitor of the IGF-IR. RESULTS: We showed that PPP efficiently blocks growth and viability of uveal melanoma cells in cultures and causes tumor regression in xenografted mice. In addition, treatment with PPP inhibited several mechanisms involved in metastasis, including tumor cell adhesion to extracellular matrix proteins, activity and expression of matrix metalloproteinase 2, and cell migration as well as invasion through basement membranes and endothelial cell layers. Furthermore, PPP significantly delayed establishment of uveal melanoma tumors and drastically reduced the incidence of liver metastasis in mice. CONCLUSIONS: Our data suggest that IGF-IR is crucial for growth and survival as well as invasion and metastasis of uveal melanoma cells. Targeting this receptor may therefore comprise a strategy to treat ongoing disease (today incurable) as well as a strategy to prevent development of metastases in patients with primary disease.     

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.     

Upcoming translational challenges for uveal melanoma

The past few years have witnessed major advances in the understanding of the molecular landscape of uveal melanoma (UM). The discovery of a mutational background that is completely different from the one of skin melanoma has granted to UM a stand-alone status. The absence of effective therapy for metastatic disease offers now a chessboard for targeted therapy but at the same time urges preclinical science to develop accordingly, to guide the use of economical resources to the best profit of patients. This review describes the current knowledge on the biology of this disease and discusses the challenges that must be undertaken to translate this knowledge into real benefit for patients.     

Immune expression and inhibition of heat shock protein 90 in uveal melanoma.

PURPOSE: To examine the immunohistochemical profile of heat shock protein 90 (Hsp90) in uveal melanoma and the cytotoxicity of an Hsp90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in uveal melanoma cell lines. EXPERIMENTAL DESIGN: Hsp90 expression was determined by immunohistochemistry in 44 paraffin-embedded sections of primary human uveal melanoma and in five uveal melanoma cell lines (92.1, OCM-1, MKT-BR, SP6.5, and UW-1). Sulforhodamine B-based proliferation assay was used to compare uveal melanoma cell growth with a range of concentrations of 17-AAG. Changes in cell migration, invasion, cell cycle fractions, and apoptotic activity were also evaluated. Expression of intracellular proteins was determined by Western blot analysis after 17-AAG exposure. RESULTS: Immunohistochemical expression of Hsp90 was identified in 68% of the paraffin-embedded sections and significantly associated with largest tumor dimension (P = 0.03). 17-AAG significantly reduced the proliferation rates of uveal melanoma cell lines, with concentrations of 100 to 0.1 micromol/L. 17-AAG also significantly reduced the migratory and invasive capabilities of uveal melanoma cell lines. Cell cycle analysis showed that 17-AAG induced accumulations of cells in G(1). Caspase-3 protease activity analysis, a marker for apoptosis, showed a significant increase after drug exposure. The cytotoxic effect of 17-AAG was associated with decreased levels of phosphorylated Akt and cyclin-dependent kinase 4. CONCLUSIONS: The immunohistochemical expression of Hsp90 in uveal melanoma indicates worse prognosis. To the best of our knowledge, this is the first report showing the inhibitory effect on uveal melanoma cells using 17-AAG to target Hsp90. Therefore, Hsp90 may be used as a potential target for treatment of patients with uveal melanoma.     

Uveal melanoma dormancy: an acceptable clinical endpoint?

Uveal melanoma is a rare but life-threatening malignancy. Over the past decades, the morbidity of uveal melanoma has been markedly reduced as a result of advances in the diagnostic ability to detect smaller tumors at an earlier stage. This has allowed for the use of more conservative treatments, avoiding enucleation. Mortality, however, has remained unchanged. This indicates that life expectancy is independent of local tumor control. Metastatic disease, the leading cause of death, is usually diagnosed many years later, despite successful treatment of the primary tumor, and at a late stage, when no effective therapy is available. These observations suggest that the disease was already disseminated at the time of tumor diagnosis. The detection of circulating malignant cells in the bloodstream of patients at different time points in the course of the disease supports this observation. Tumor dormancy has been considered as the leading theory for this intriguing delayed appearance of metastasis. Recent knowledge gained about the biological behavior of uveal melanoma as well as novel potential therapeutic targets are presented in this review.     

Targeted therapy for uveal melanoma

Uveal melanoma is the most common primary intra-ocular malignancy in adults. Overall mortality rate remains high because of the development of metastatic disease, which is highly resistant to systemic therapy. Improved understanding of the molecular pathogenesis of cancers has led to a new generation of therapeutic agents that interfere with a specific pathway critical in tumor development or progression. Although no specific genes have been linked to the pathogenesis of uveal melanoma, which differs from that of cutaneous melanoma, progress has been made in identifying potential targets involved in uveal melanoma apoptosis, proliferation, invasion, metastasis, and angiogenesis. This review focuses on the prospects for improving the systemic therapy of uveal melanoma using molecularly targeted agents that are currently in clinical use as well as agents being tested in clinical trials. Preclinical studies suggest potential benefit of inhibitors of Bcl-2, ubiquitin-proteasome, histone deactylase, mitogen-activated protein kinase and phosphatidylinositol-3-kinase-AKT pathways, and receptor tyrosine kinases. Modifiers of adhesion molecules, matrix metalloproteinase, and angiogenic factors also have demonstrated potential benefit. Clinical trials of some of these approaches have been initiated in patients with metastatic uveal melanoma as well as in the adjuvant setting after primary therapy.     

International uveal melanoma incidence trends in view of a decreasing proportion of morphological verification

The introduction of eye-preserving therapies for uveal melanoma in the 1970s complicates time trend analyses of the uveal melanoma incidence because the proportion of morphologically verified uveal melanoma has been decreasing over the decades. We carried out incidence trend analyses, based on data from internationally accredited population-based cancer registries throughout the world that take missing data on topography, morphology and basis of diagnosis of eye tumours into account. We selected incidence data of cancer registries that were included in Cancer Incidence In 5 Continents, Volumes VI-VIII covering a registration period of at least 15 years (usually 1983 to 1997) and classified each eye cancer as morphologically verified uveal melanoma, clinically diagnosed uveal melanoma, uveal melanoma identified as DCO case (Death certificate only), possibly uveal melanoma, other eye tumour or unclassifiable eye tumour and calculated age-standardized incidence rates by 3-year calendar periods using the World Standard Population as the reference. The uveal melanoma incidence decline in the United States SEER Caucasian population is due mainly to an incidence decline in the early registration period (from 1974-76 to 1986-88). The data from France and Italy suggest a recent increase in incidence. Uveal melanoma diagnosed clinically increasingly contribute to the overall uveal melanoma incidence over time. Combining all registries, the proportion of morphologically verified uveal melanoma decreased from 82% in 1983-87 to 75% in 1993-97. Uveal melanoma incidence rates remained quite stable during the period 1983-97. The interpretation of uveal melanoma incidence trends is complicated by missing data on topography within the eye, morphology and basis of diagnosis.     

Conjunctival Melanoma - Epidemiological Trends and Features

Conjunctival melanoma is a rare but sight and life threatening malignancy. It accounts for 2%–5% of all ocular tumours and 5%–7% of all ocular melanomas with an incidence of 0.2–0.8 per million in the Caucasian population with rare cases reported in the non-Caucasians. In recent decades the incidence of uveal melanoma has been relatively stable whilst conjunctival and cutaneous melanoma have shown increasing incidence which may be connected to the result of environmental exposure to ultraviolet light. The dissimilarity in incidence between light and dark pigmented individuals observed in conjunctival melanomas compared to uveal and cutaneous melanomas may be related to differences in their histological structures and genetic profile. Recent molecular biological studies support the fact that each type of melanoma undergoes its own molecular changes and has characteristic biological behaviour. Further studies are required for each type of melanoma in order to ascertain their individual etiology and pathogenesis and based on this knowledge develop relevant preventative and treatment procedures.     

Detection of BRAF gene mutation in primary choroidal melanoma tissue

Numerous BRAF mutations have been detected in melanoma biopsy specimens and cell lines. In contrast, several studies report lack of BRAF mutations in uveal melanoma including primary and metastatic choroidal and ciliary body melanomas. To our knowledge, for the first time, here we report a case of choroidal melanoma harboring the BRAF mutation (V600E). The activation of RAF/MEK/ERK pathway, although independent of BRAF mutation, was reported in uveal melanoma. The presence of V600E mutation indicates that the RAF/MEK/ERK pathway, in addition to cutaneous melanoma progression, may play a role in the choroidal melanoma development.     

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.     

Decreased endothelin receptor B expression in large primary uveal melanomas is associated with early clinical metastasis and short survival

The most devastating aspect of cancer is the metastasis of tumour cells to organs distant from the original tumour site. The major problem facing oncologists treating uveal melanoma, the most common cancer of the eye, is metastatic disease. To lower mortality, it is necessary to increase our understanding of the molecular genetic alterations involved in this process. Using suppression subtractive hybridisation, we have analysed differential gene expression between four primary tumours from patients who have developed clinical metastasis and four primary tumours from patients with no evidence of metastasis to date. We have identified endothelin receptor type B as differentially expressed between these tumours and confirmed this observation using comparative multiplex RT-PCR. In a further 33 tumours, reduced endothelin receptor type B expression correlated with death from metastatic disease. Reduced expression also correlated with other known prognostic indicators, including the presence of epithelioid cells, chromosome 3 allelic imbalance and chromosome 8q allelic imbalance. Endothelin receptor type B expression was also reduced in four out of four primary small cell lung carcinomas compared to normal bronchial epithelium. We also show that the observed down-regulation of endothelin receptor type B in uveal melanoma was not due to gene deletion. Our findings suggest a role for endothelin receptor type B in the metastasis of uveal melanoma and, potentially, in the metastasis of other neural crest tumours.     

Prognostic factors in uveal melanoma

Uveal melanoma is the most common primary intraocular malignant tumour, with an annual incidence of approximately six cases per million per year. Approximately 40% of patients with posterior uveal melanoma develop metastatic melanoma to the liver within 10 years after initial diagnosis. Despite high accuracy of diagnosis and availability of various methods of treatment; the mortality due to uveal melanoma has remained unchanged. The prognosis in uveal melanoma depends on clinical, histopathological and cytological factors. Clinical factors that relate to prognosis include location, size, and configuration of the tumour. Uveal melanoma can arise in the iris, the ciliary body or the choroid. Iris melanomas have the best prognosis and ciliary body melanomas have the worst prognosis. Based on retrospective studies, the mortality rates for uveal melanoma for comparable sized tumours treated by enucleation or other globe conserving methods such as radiotherapy appear to be similar. Histopathological factors such as cell type, mitotic activity, microcirculation architecture, tumour-infiltrating lymphocytes and the presence of extrascleral extension are also significant predictors of survival. More recently, cytological factors such as cell proliferation, cytogenic, and molecular genetic prognostic markers have been identified with the hope of detecting high risk cases for adjuvant systemic immune therapy or chemotherapy. At present, the role of these therapeutic methods is not clearly established.     

Tumor-targeting TRAIL expression mediated by miRNA response elements suppressed growth of uveal melanoma cells

Malignant uveal melanoma severely damages eye function and is prone to metastasize to other organs. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent to treat uveal melanoma because of its induction of apoptosis in cancer cells both at primary and metastatic sites. However, TRAIL therapy lacks tumor specificity in the current delivery systems for uveal melanoma treatment, thereby causing cytotoxiciy to normal tissues. To improve uveal melanoma specificity of adenovirus-based TRAIL introduction, we used miRNA response elements (MREs) of miR-34a, miR-137 and miR-182, which have been shown to have reduced expression in uveal melanoma cells, to regulate its expression. miR-34a, miR-137 and miR-182 all had lower expression levels in uveal melanoma cell lines, compared with normal cells. MREs-regulated luciferase activity was reduced in normal cell lines, but not significantly attenuated in uveal melanoma cells. The infection of MRE-regulated TRAIL-expressing adenoviral vector (Ad-TRAIL-3MREs) led to high level of TRAIL expression in uveal melanoma cell lines, but not in normal cells. Strong expression of TRAIL had a high anti-tumor capacity by inducing apoptosis in uveal melanoma cells. In contrast, Ad-TRAIL-3MREs had no cytotoxicity to normal cell lines. Animal experiments further confirmed tumor-suppressing effect of Ad-TRAIL-3MREs on uveal melanoma xenografts and its biosafety to hepatic tissues. Collectively, we constructed an MRE-directed TRAIL-expressing adenoviral vector and provided evidence that this vector possessed high anti-tumor activity and uveal melanoma specificity.     

Increased chondroitin sulphate proteoglycan expression (B5 immunoreactivity) in metastases of uveal melanoma

Background: Metastatic uveal melanoma has a poor prognosis andlimited therapeutic options. Proteoglycans are involved in tumorcell invasion and metastatic behavior. The mAbB5 stains a chondroitinsulphate proteoglycan (CSPG) on cutaneous melanoma cells. Here,we compare the B5-staining of CSPG in primaries and metastasesof uveal melanoma. Material and methods: Immunohistopathological staining was performedin 15 cutaneous and 39 uveal melanoma samples. A score for intracellularand surface staining was established. B5 staining was comparedin primaries and metastases of uveal melanoma using Student'st-test. Results: Eight of 11 (73%) uveal melanoma metastases were positivefor B5-staining whereas only 5 of 28 (18%) primary uveal melanomasamples were B5-positive (P < 0.001). Nine of 15 cutaneousmelanoma samples (60%) were B5-positive without significantdifference between primary and metastatic lesions. Surface stainingwas found both on uveal melanoma metastases and cutaneous melanomas. Conclusions: CSPG was expressed significantly more often inmetastases than in primaries of uveal melanoma. It potentiallymay be one factor associated with metastatic spread. Furtherstudies are needed to determine its use as prognostic factor.The mAbB5 may also be a promising tool for immunotherapy dueto its strong staining of CSPG on the surface of cutaneous andmetastatic uveal melanoma cells. Key words: uveal melanoma, ocular melanoma, chondroitin sulphate proteoglycan, immunotherapy, immunohistochemistry