Significance, specificity, and ultrastructural localization of HMB-45 antigen in pigmented ocular tumors

S100 as Serum Tumor Marker in Advanced Uveal Melanoma

S100 protein is routinely used as a serum tumor marker in advanced cutaneous melanoma. However, there is scarce and inconclusive evidence on its value in monitoring disease progression of uveal melanoma. In this monocenter study, we retrospectively assessed the connection between documented S100 protein levels of patients suffering from stage IV uveal melanoma and the clinical course of disease. Where available, we analyzed expression of S100 in melanoma metastases by immunohistochemistry. A total of 101 patients were included, 98 had available serum S100 levels, and in 83 cases, sufficient data were available to assess a potential link of S100 with the clinical course of the uveal melanoma. Only 12 of 58 (20.7%) patients had elevated serum levels at first diagnosis of stage IV disease. During progressive disease, 54% of patients showed rising serum S100 levels, while 46% of patients did not. Tumor material of 56 patients was stained for S100. Here, 26 (46.4%) showed expression, 19 (33.9%) weak expression, and 11 (19.6%) no expression of S100. Serum S100 levels rose invariably in all patients with strong expression throughout the course of disease, while patients without S100 expression in metastases never showed rising S100 levels. Thus, the value of S100 serum levels in monitoring disease progression can be predicted by immunohistochemistry of metastases. It is not a reliable marker for early detection of advanced disease.

Recent Advances and Challenges in Uveal Melanoma Immunotherapy

Simple Summary

Uveal melanoma is the most common primary intraocular malignancy in adults. Although it can be controlled locally, half of the patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Existing therapies, such as chemotherapy and targeted therapies, induce only minimal responses. This review focuses on newly published research on immunotherapy. We highlight expanding treatments and their clinical outcomes, as well as propose promising new treatments and feasible checkpoints. Based on these findings, we provide innovative insights into feasible strategies for the treatment of patients with uveal melanoma.

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Compared to cutaneous melanoma (CM), which mainly harbors BRAF or NRAS mutations, UM predominantly harbors GNAQ or GNA11 mutations. Although primary UM can be controlled locally, approximately 50% of patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Unfortunately, chemotherapy and targeted therapies only induce minimal responses in patients with metastatic UM, with a median survival time of only 4–5 months after metastasis detection. Immunotherapy agents, such as immune checkpoint inhibitors, have achieved pioneering outcomes in CM but have shown limited effects in UM. Researchers have explored several feasible checkpoints to identify options for future therapies. Cancer vaccines have shown little in the way of therapeutic benefit in patients with UM, and there are few ongoing trials providing favorable evidence, but adoptive cell transfer-related therapies seem promising and deserve further investigation. More recently, the immune-mobilizing monoclonal T-cell receptor against the cancer molecule tebentafusp showed impressive antitumor effects. Meanwhile, oncolytic viruses and small molecule inhibitors have also gained ground. This review highlights recent progress in burgeoning treatments and provides innovative insights on feasible strategies for the treatment of UM.

Tebentafusp for the treatment of metastatic uveal melanoma

Uveal melanoma is a rare disease; nevertheless, it is the most common primary intraocular malignancy among adults. Approximately half of affected patients will suffer from metastatic disease, mostly to the liver. No standard-of-care treatment exists for these patients. Median progression-free survival and overall survival for all types of treatment, including checkpoint inhibitors, have remained poor. However, the most recent phase III study results for tebentafusp, a member of a new-in-class molecule, are raising hopes for stage IV uveal melanoma patients. In this review, we examine the current literature, focusing on the most recent trial results for this new reagent. We evaluate the latest clinical results for tebentafusp and aim to shed light on its immunological strategy.

Immunotherapies for the Treatment of Uveal Melanoma-History and Future

Background: Uveal melanoma is the most common primary intraocular malignancy among adults. It is, nevertheless, a rare disease, with an incidence of approximately one case per 100,000 individuals per year in Europe. Approximately half of tumors will eventually metastasize, and the liver is the organ usually affected. No standard-of-care treatment exists for metastasized uveal melanoma. Chemotherapies or liver-directed treatments do not usually result in long-term tumor control. Immunotherapies are currently the most promising therapy option available. Methods: We reviewed both relevant recent literature on PubMed concerning the treatment of uveal melanoma with immunotherapies, and currently investigated drugs on ClinicalTrials.gov. Our own experiences with immune checkpoint blockers are included in a case series of 20 patients. Results: Because few clinical trials have been conducted for metastasized uveal melanoma, no definitive treatment strategy exists for this rare disease. The outcomes of most immunotherapies are poor, especially compared with cutaneous melanoma. However, encouraging results have been found for some very recently investigated agents such as the bispecific tebentafusp, for which a remarkably increased one-year overall survival rate, and similarly increased disease control rate, were observed in early phase studies. Conclusions: The treatment of metastatic uveal melanoma remains challenging, and almost all patients still die from the disease. Long-term responses might be achievable by means of new immunological strategies. Patients should therefore be referred to large medical centers where they can take part in controlled clinical studies.

Mice Expressing Myc in Neural Precursors Develop Choroid Plexus and Ciliary Body Tumors

Choroid plexus tumors and ciliary body medulloepithelioma are predominantly pediatric neoplasms. Progress in understanding the pathogenesis of these tumors has been hindered by their rarity and lack of models that faithfully recapitulate the disease. Here, we find that endogenous Myc proto-oncogene protein is down-regulated in the forebrain neuroepithelium, whose neural plate border domains give rise to the anterior choroid plexus and ciliary body. To uncover the consequences of persistent Myc expression, MYC expression was forced in multipotent neural precursors (nestin-Cre:Myc), which produced fully penetrant models of choroid plexus carcinoma and ciliary body medulloepithelioma. Nestin-mediated MYC expression in the epithelial cells of choroid plexus leads to the regionalized formation of choroid plexus carcinoma in the posterior domain of the lateral ventricle choroid plexus and the fourth ventricle choroid plexus that is accompanied by loss of multiple cilia, up-regulation of protein biosynthetic machinery, and hydrocephalus. Parallel MYC expression in the ciliary body leads also to up-regulation of protein biosynthetic machinery. Additionally, Myc expression in human choroid plexus tumors increases with aggressiveness of disease. Collectively, our findings expose a select vulnerability of the neuroepithelial lineage to postnatal tumorigenesis and provide a new mouse model for investigating the pathogenesis of these rare pediatric neoplasms.

HMB-45 Immunostaining and Ultrastructure of Melanocytic Hyperplasia in Pigmented Basal Cell Carcinomas

The pigmented variant of basal cell carcinoma (PBCC) may be clinically misinterpreted as malignant melanoma. Histologically this variant is characterized by the presence of functional melanocytes distributed among epithelial tumor cells, particularly in superficial areas. Our finding of a case of PBCC with numerous atypical HMB-45-positive melanocytes prompted us to analyze the morphologic and immunohistochemical features of 20 consecutive cases of PBCC. Four additional cases with numerous large HMB-45-positive melanocytes, also present in the most invasive tumor nests, were found. Ultrastructural examination was performed in two selected cases. Large melanocytes with immature (stages I and II) and mature melanosomes were found between epithelial tumor cells having desmosomes and tonofilaments. Our cases highlight the presence of immature melanosomes and subsequent HMB-45 immunostaining in hyperplastic melanocytes within PBCC, an underrecognized feature that should be considered to avoid a misdiagnosis of malignant melanoma.

Oncogenic G Protein GNAQ Induces Uveal Melanoma and Intravasation in Mice

GNAQ and GNA11 are heterotrimeric G protein alpha subunits, which are mutated in a mutually exclusive pattern in most cases of uveal melanoma, one of the most aggressive cancers. Here we introduce the first transgenic mouse model of uveal melanoma, which develops cancers induced by expression of oncogenic GNAQ(Q209L) under control of the Rosa26 promoter. Disease penetrance is 100% by 3 months of age, with 94% of mice also developing lung tumors. In this model, the Yap protein of the Hippo pathway is activated in the eyes, and blood vessels near the lesions in the head and lungs exhibit melanocytic invasion. While full transcription levels are not necessary for GNAQ(Q209L) to transform mouse melanocytes, we obtained suggestive evidence of a selective advantage for increased GNAQ(Q209L) expression in human tumors. Intriguingly, enforced expression of GNAQ(Q209L) progressively eliminated melanocytes from the interfollicular epidermis in adults, possibly explaining the near absence of GNAQ(Q209) mutations in human epithelial melanomas. The mouse model also exhibited dermal nevi and melanocytic neoplasms of the central nervous system, accompanied by impaired hearing and balance, identifying a novel role for GNAQ in melanocyte-like cells of the inner ear. Overall, this model offers a new tool to dissect signaling by oncogenic GNAQ and to test potential therapeutics in an in vivo setting where GNAQ(Q209L) mutations contribute to both the initiation and metastatic progression of uveal melanoma.

Long overall survival after dendritic cell vaccination in metastatic uveal melanoma patients

PURPOSE

To assess the safety and efficacy of dendritic cell vaccination in metastatic uveal melanoma.

DESIGN

Interventional case series.

METHODS

We analyzed 14 patients with metastatic uveal melanoma treated with dendritic cell vaccination. Patients with metastatic uveal melanoma received at least 3 vaccinations with autologous dendritic cells, professional antigen-presenting cells loaded with melanoma antigens gp100 and tyrosinase. The main outcome measures were safety, immunologic response, and overall survival.

RESULTS

Tumor-specific immune responses were induced with dendritic cell vaccination in 4 (29%) of 14 patients. Dendritic cell-vaccinated patients showed a median overall survival with metastatic disease of 19.2 months, relatively long compared with that reported in the literature. No severe treatment-related toxicities (common toxicity criteria grade 3 or 4) were observed.

CONCLUSIONS

Dendritic cell vaccination is feasible and safe in metastatic uveal melanoma. Dendritic cell-based immunotherapy is potent to enhance the host's antitumor immunity against uveal melanoma in approximately one third of patients. Compared with other prospective studies with similar inclusion criteria, dendritic cell vaccination may be associated with longer than average overall survival in patients with metastatic uveal melanoma.

Clinical, pathologic, and imaging features and biological markers of uveal melanoma

Uveal melanoma has unique clinical and pathologic features including virtually exclusive metastasis to the liver in high-risk cases. In this chapter, the clinical findings in uveal melanoma and diagnostic methods including imaging tests and serum markers are described. Additionally, the histopathologic features including the modified Callender classification and immunohistochemical findings of uveal melanoma are described.

Conjunctival melanoma: a review of conceptual and treatment advances

The aim of this study was to review the available literature and identify recent advances in the classification and management of conjunctival melanoma (CM) for clinicians working in this field. English-based articles were identified using the MEDLINE^® database, and additional cited works not detected in the initial search were also obtained. Articles were assessed according to the Australian National Health and Medical Research Council levels of evidence criteria. Review of the literature indicated that the current classification and management of CM is predominantly based upon primarily nonrandomized, single-institution, retrospective case series. While these studies provide the basis for the recent seventh edition of the tumor node metastasis staging classification, this classification more accurately reflects the current knowledge of prognostic factors for CM. Application of this revised classification system together with prospective trials will provide the opportunity for future consistent and comparable data collection across centers, and it will improve the quality of evidence upon which current classification and management of CM is based. Furthermore, the high risk of local recurrence with current standard management suggests that adjuvant therapy, particularly mitomycin C and/or brachytherapy, may improve outcomes regardless of clinical staging. Finally, the use of sentinel lymph node biopsy may have significant benefit for a select group of CM patients.

The effect of blue light exposure in an ocular melanoma animal model

BACKGROUND

Uveal melanoma (UM) cell lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to determine if similar effects could be seen in vivo, we investigated the effect of blue light exposure in a xenograft animal model of UM.

METHODS

Twenty New Zealand albino rabbits were injected with 1.0 x 10(6) human UM cells (92.1) in the suprachoroidal space of the right eye. Animals were equally divided into two groups; the experimental group was exposed to blue light, while the control group was protected from blue light exposure. The eyes were enucleated after sacrifice and the proliferation rates of the re-cultured tumor cells were assessed using a Sulforhodamine-B assay. Cells were re-cultured for 1 passage only in order to maintain any in vivo cellular changes. Furthermore, Proliferating Cell Nuclear Antigen (PCNA) protein expression was used to ascertain differences in cellular proliferation between both groups in formalin-fixed, paraffin-embedded eyes (FFPE).

RESULTS

Blue light exposure led to a statistically significant increase in proliferation for cell lines derived from intraocular tumors (p < 0.01). PCNA expression was significantly higher in the FFPE blue light treated group when compared to controls (p = 0.0096).

CONCLUSION

There is an increasing amount of data suggesting that blue light exposure may influence the progression of UM. Our results support this notion and warrant further studies to evaluate the ability of blue light filtering lenses to slow disease progression in UM patients.

Pigmented Episcleral Deposits after Brachytherapy of Uveal Melanoma

PURPOSE

To describe the characteristics and evolution of pigmented episcleral deposits after brachytherapy for uveal melanoma to determine their origin and association with melanoma-related mortality.

DESIGN

Noncomparative case series.

PARTICIPANTS

Two hundred eleven patients (108 males, 103 females; median age, 61 years; range, 14-88 years) who were treated with a single ruthenium and iodine plaque therapy (median dose to tumor base, 475 Gy and 392 Gy, respectively) for a choroidal and ciliary body melanoma. Median tumor diameter and height were 12 mm and 5.5 mm, respectively. Eighty-eight patients were treated prospectively during the study.

METHODS

The number and location of pigmented episcleral deposits were recorded under the slit lamp during each visit after brachytherapy. The association of the deposits with tumor characteristics and survival was analyzed with logistic regression and Kaplan-Meier analysis, respectively.

MAIN OUTCOME MEASURES

Number and location of episcleral deposits, melanoma-related mortality.

RESULTS

The pigmented episcleral deposits ranged from black and brownish spots to slightly thickened patches. Most deposits appeared within the first 6 months after brachytherapy. By 1 year, 85% (95% confidence interval, 77-93) of eyes had at least 1 deposit (median, 6). The deposits increased in number until 7 years from irradiation, and decreased with increasing distance from tumor center. An association between the number of deposits at 1 and 2 years and subsequent melanoma-related mortality could not be confirmed (P = 0.80 and P = 0.31, respectively).

CONCLUSIONS

Pigmented macrophage-related episcleral deposits are found in most eyes with uveal melanoma after brachytherapy. Their association with plaque size and isotope rather than with tumor size suggests that radiation atrophy of retinal pigment epithelium and choroid in addition to tumor regression contributes to the formation of the deposits. Knowledge of their existence may save patients from unnecessary enucleation.

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.

Malignant melanoma with neuroendocrine differentiation: clinical, histological, immunohistochemical and ultrastructural features of three cases

AIM

To document the clinical, histological, immunohistochemical and ultrastructural features of three malignant melanomas showing neuroendocrine differentiation.

METHODS AND RESULTS

Three patients, two with primary cutaneous melanoma and one with nasal mucosal melanoma, subsequently developing or simultaneously presenting with metastatic malignant melanoma, were studied by conventional histological technique, immunohistochemistry of formalin-fixed paraffin-wax embedded tissues, and electron microscopy of epoxy-resin-embedded tumour tissue. Tumours showed either small cell or conventional malignant melanoma cell morphology. One of the three primary melanocytic lesions (the nasal melanoma) exhibited neuroendocrine differentiation immunohistochemically. All three metastatic malignant melanomas showed, in varying combinations, immunohistochemical and ultrastructural evidence for neuroendocrine differentiation: they were positive for the melanocytic markers, S100 protein, HMB-45, Melan-A and tyrosinase, and the neuroendocrine markers chromogranin, synaptophysin and neurofilament protein. Ultrastructural study in two of the metastases revealed neuroendocrine granules but no lattice-bearing melanosomes.

CONCLUSIONS

The cases described are the most comprehensively investigated malignant melanomas showing neuroendocrine differentiation to date, and the first to document neuroendocrine differentiation ultrastructurally in these tumours. Malignant melanoma with neuroendocrine differentiation therefore needs to be recognized among the other, better known variants of malignant melanoma.

Metastatic small cell malignant melanoma: a case requiring immunoelectronmicroscopy for the demonstration of lattice-deficient melanosomes

A case of metastatic malignant melanoma exhibiting small cell morphology is described. The patient had had a previous primary nodular small cell melanoma. The metastatic tumor was examined by conventional histology, light microscope immunohistochemistry, conventional electron microscopy, and ultrastructural immunolabeling. It consisted of small cells, which, however, varied in size and were present in distinct but merging areas. Tumor cells were negative for S-100 protein and very focally positive for cytokeratin: these findings in combination with small cell morphology suggested the possibility of small cell carcinoma. However, other melanocytic markers were positive. Neuroendocrine markers were negative. By electron microscopy, tumor cells lacked unambiguous melanosomes but contained paranuclear aggregates of nondescript granules. Following ultrastructural immunolabeling, these were found to be decorated with gold-labeled HMB-45 antibodies, thereby confirming them as lattice-deficient melanosomes. This tumor is an uncommon example of malignant melanoma where immunoultrastructural analysis helped clarify the nature of otherwise nondescript granules as true but lattice-deficient melanosomes. This is also the first case of small cell melanoma to be studied by electron microscopy.

Ocular Melanoma Metastatic to Skin: The Value of HMB-45 Staining

BACKGROUND

Cutaneous metastatic disease is an important finding that may represent the first sign of systemic cancer, or, if already known, that may change tumor staging and thus dramatically altered therapeutic plans. Although cutaneous metastases are relatively frequent in patients with cutaneous melanoma, they are less so from ocular melanoma.

OBJECTIVE

To demonstrate the value of HMB-45, staining in the detection of ocular melanoma metastatic to skin.

METHODS

The immunohistochemical stain HMB-45 a monoclonal antibody directed against intact human melanoma cells, was employed on a skin biopsy specimen from a cutaneous tumor.

RESULTS

HMB-45 staining was positive in the atypical hyperchromatic cells of the deep dermis.

CONCLUSION

HMB-45 may be of value in the detection of ocular melanoma metastatic to skin. Cutaneous metastatic disease is a somewhat common and extremely important diagnosis. Although cutaneous metastases from cutaneous melanoma are relatively frequent, those from ocular melanomas are less so. Use of histochemical staining, especially the HMB-45 stain, allows confirmation of the diagnosis.

Macrophages and microcirculation in regressed and partially regressed irradiated choroidal and ciliary body melanomas

PURPOSE

To investigate how tumour-infiltrating macrophages and microcirculation attributes of uveal melanomas regressed after brachytherapy and whether primarily enucleated melanomas differ.

METHODS

A case-control analysis of 34 matched pairs of irradiated and nonirradiated choroidal and ciliary body melanomas with main outcome variables being area of necrosis, extravascular matrix loops and networks, tumour-infiltrating macrophages in nonnecrotic areas identified with mAb PG-M1 to the CD68 epitope, and microvascular density (MVD) determined by mAb QBEND/10 to the CD34 epitope.

RESULTS

Comparison of primarily enucleated eyes to eyes with irradiated, secondarily enucleated melanomas revealed significantly more necrosis (median difference, +9%, P = 0.0012) and lower MVD (median difference, -10 counts/0.313 mm(2), P = 0.011) in the latter. In eyes managed with brachytherapy, loops and networks tended to be less frequent (P = 0.077). Number and type of macrophages were similarly distributed, being moderate to high in about 95% (P = 0.67) of the matched pairs, and intermediate to dendritic in 79% (P = 0.90). In the irradiated eyes, presence of epithelioid cells and the number and type of macrophages showed no association with microcirculation attributes, whereas in the primarily enucleated tumours, high number of macrophages was associated with high MVD (P < 0.001).

CONCLUSIONS

This study suggests that regression after brachytherapy reduces MVD. The difference cannot be attributed to different numbers of tumour-infiltrating macrophages and different cell type in nonnecrotic areas of the tumour.

Differential immunoreactivity of melanocytic lesions of the conjunctiva

AIMS

To evaluate the expression of S100NKI/C3 and HMB45 antigens in melanocytic lesions of the conjunctiva and the ability of HMB45 to aid assessment of neoplasia.

METHODS AND RESULTS

Stored formalin-fixed specimens of conjunctival melanomas and primary acquired melanosis were considered as participants and conjunctival naevi and racial melanosis as controls. Ninety-seven conjunctival melanocytic lesions were analysed using formalin-fixed paraffin-embedded material. These included 20 melanomas arising in the context of primary acquired melanosis (PAM), 22 melanomas arising without evidence of pre-existing PAM, seven cases of PAM with atypia, nine cases of PAM with no atypia, 35 conjunctival naevi and four cases of racial melanosis. S100 and NKI/C3 were similarly expressed in all lesions, with at least one of these markers positive in 100% of the lesions examined. HMB45 was expressed in 72.7% of primary melanomas and 85% of melanomas in the context of PAM; 42.8% of PAM with atypia expressed HMB45 while it was expressed in 11.1% of PAM without atypia and 8.5% of naevi. Racial melanosis cases did not express HMB45. S100 and NKI/C3 were expressed to a similar extent in all groups.

CONCLUSIONS

S100 and NKI/C3 are useful markers to assess the extent of melanocytic lesions in the conjunctiva. HMB45 immunoreactivity can act as a useful aid to histopathology for the distinction of benign from malignant conjunctival lesions, particularly in the context of primary acquired melanosis.

TGF-beta in uveal melanoma

Uveal melanoma is the most common primary ocular cancer among adults and patients with distant metastases seldom survive longer than a year. Melanomas of the eye have the advantage of growing in the special environment of an immune privileged site and it has long been shown, that the special immunosuppressive properties of the intraocular microenvironment are strongly mediated by cytokines, especially transforming growth factor-beta (TGF-beta). Here, we sought to investigate the presence of TGF-beta in surgically removed uveal melanoma specimens using immunohistochemical methods to verify possible autocrine mechanisms. Immunocytochemistry for pan-TGF-beta and TGF-beta(2) was performed on 13 melanoma specimens using an alkaline phosphatase labeling procedure. Melanocytic origin of the tumors was confirmed by HMB-45 staining. All tissue samples exhibited positive staining using either pan-TGF-beta or TGF-beta(2) antibody regardless of cell-type, size of the tumor, or tumor location. The intensity of staining did not vary significantly within a given tumor. All tumors stained positive against the HMB-45 antibody. Many cytokines have been found to act on melanoma tumors. The presence of the TGF-beta(2) isoform in all specimens points to progressive tumor-growth as has been shown for melanomas of the skin. Based on our immunohistochemical findings and the immunosuppressive properties of TGF-beta, we suppose that ocular melanomas should be able to create their own immunosuppressive environment even in the uvea, which might be a non-privileged site.

Immunohistochemical diagnosis of malignant melanoma of the conjunctiva and uvea: comparison of the novel antibody against melan-A with S100 protein and HMB-45

A novel antibody A103, which recognizes melan-A/MART-1, has been found to be more sensitive than the antibody HMB-45, which recognizes gp100, in melanocytic lesions of the skin and might therefore also be useful in the diagnosis of uveal and conjunctival melanocytic lesions. In this study we compared the staining characteristics of anti-melan-A, anti-S100 protein and HMB-45 in 13 conjunctival, 11 iris and 37 ciliary and choroidal malignant melanomas. The ciliary and choroidal melanomas comprised 13 spindle cell (10 spindle B and three spindle A), 14 mixed cell and 10 epithelioid cell tumours. In the conjunctival melanomas the diagnostic sensitivity was 100% for anti-S100 and anti-melan-A and 85% for HMB-45. In the iris melanomas the sensitivity was 100% for anti-S100 and anti-melan-A and 55% for HMB-45. A high staining intensity of anti-melan-A was particularly noticed in iris melanomas. In the choroidal malignant melanomas, the spindle cell and mixed cell types showed a sensitivity of only 69-79% with all three antibodies. In the epithelioid cell type the sensitivity was 80% for anti-S100 and 100% for HMB-45 and anti-melan-A. In conclusion, anti-melan-A was found to be a useful addition to antibody panels for ocular melanocytic lesions. Anti-melan-A has a higher sensitivity than HMB-45 in conjunctival and iris melanomas, but the sensitivity is similar to HMB-45 in choroidal melanomas. Anti-melan-A stains in a very similar pattern to anti-S100, but the staining intensity of anti-melan-A is higher than that of anti-S100 in iris melanoma.

Microvascular loops and networks as prognostic indicators in choroidal and ciliary body melanomas

BACKGROUND

Malignant melanoma of the ciliary body and choroid of the eye is a tumor that disseminates frequently, and 50% of the diagnosed patients die within 10 years. We investigated the hypothesis that, by histopathologic analysis of the arrangement of microvessels (i.e., small blood vessels) in loops and networks, we might be able to differentiate better those patients with a favorable prognosis from those with a poor prognosis.

METHODS

We conducted a population-based, retrospective cohort study of melanoma-specific and all-cause mortality for 167 consecutive patients who had an eye surgically removed because of malignant choroidal or ciliary body melanoma during the period from 1972 through 1981. Microvascular loops and networks were evaluated independently by two pathologists who were unaware of patient outcome.

RESULTS

Microvascular patterns could be assessed in 134 (80%) of 167 melanoma specimens. The 10-year probability of melanoma-specific survival was worse if microvascular loops (0.45 versus 0.83; two-sided P<.0001) and networks (0.41 versus 0.72, two-sided P<.0001) were present. In multivariate Cox regression analysis of melanoma-specific survival, the hazard ratios were 1.66 (95% confidence interval [CI] = 1.19-2.30) for the presence of loops and networks as a combined three-category variable, 2.36 (95% CI = 1.37-4.05) for the presence of epithelioid cells, 1.11 (95% CI = 1.03-1.19) for the largest basal tumor diameter (evaluated as a continuous variable), and 2.14 (95% CI = 1.25-3.67) for ciliary body involvement.

CONCLUSIONS

Patients with malignant uveal melanoma who have a favorable prognosis can be distinguished from those with a poor prognosis by histopathologic analysis of microvascular patterns in uveal melanoma tumor specimens.

High expression of immunotherapy candidate proteins gp100, MART-1, tyrosinase and TRP-1 in uveal melanoma

In the treatment of cutaneous melanoma, provisional therapeutic strategies have been designed to combat tumour load using T cells that are sensitized with peptides derived from melanoma autoantigens, such as glycoprotein 100 (gp100), melanoma antigen recognized by T cells 1 (MART-1 or MelanA), tyrosinase and tyrosinase-related protein 1 (TRP-1). We recently found that gp100, MART-1 and tyrosinase are heterogeneously expressed in human cutaneous melanoma (De Vries et al (1997) Cancer Res 57: 3223-3229). Here, we extended our investigations on expression of these immunotherapy candidate proteins to uveal melanoma lesions. Cryostat sections from 11 spindle-type, 21 mixed and epithelioid tumours and four metastasis lesions were stained with antibodies specifically recognizing gp100, MART-1, tyrosinase and TRP-1. In addition, we used the DOPA reaction to detect tyrosinase enzyme activity as a confirmation of the tyrosinase immunohistochemical results. High expression of gp100, MART-1 and tyrosinase was found in the uveal melanoma lesions: 80% of the lesions displayed 75-100% positive tumour cells. TRP-1 positivity was slightly less: approximately 65% of the lesions stained in the 75-100% positive tumour cell category. All uveal melanoma lesions were positive for the four markers studied, this being in contrast to cutaneous melanoma where 17% of the advanced primary lesions and metastases were negative. The presence of these antigens was a little lower in metastases. We conclude that uveal melanomas and their metastases express melanocyte-lineage immunotherapy candidate proteins very abundantly. Uveal melanomas differ in this respect from cutaneous melanoma, in which the expression of these immunotherapy antigens was much more heterogeneous. This makes uveal melanoma a suitable candidate tumour for immunotherapeutic approaches.

Conjunctival melanoma

Conjunctival melanoma is an uncommon tumor that is likely to recur and carries an overall mortality rate of approximately 30%. The seemingly unpredictable and enigmatic character of this entity has initiated much debate over the past decades regarding the etiology, histogenesis, prognosis, and preferred management. This review outlines the historical perspective; incidence and demographics; etiologic factors; histogenesis; cytogenetic findings; clinical characteristics; histopathologic and ultrastructural features; differential diagnoses; classifications; management of primary, recurrent, and systemic disease; survival after conjunctival melanoma; and diverse factors of potential prognostic significance. Finally, a brief outlook on present and future research objectives is provided.

Morphologic and immunocytochemical characterization of four human uveal cell lines (melanoma- and melanocytes-derived)

PURPOSE

To characterize three cell lines from human uveal melanomas and one ocular melanocyte cell line to study the specificity of several antigens in the malignant transformation of melanocytic uveal cells.

METHODS

Light microscopy (LM), transmission electron microscopy (TEM), and immunocytochemical techniques were used in the characterization of OCM-1, SP 6.5, and MKT-BR human uveal melanoma cell lines and UW-1 normal melanocyte cell line from human uvea. Several monoclonal antibodies (MoAbs) S-100, HMB-45, MNF-116, PAL-M1, NK1/C-3, IND-1, and MAAMA were used.

RESULTS

All cell lines showed an epithelioid/spindle morphology with occasional multinucleated cells, and nuclear pleomorphism. TEM showed intracytoplasmatic premelanosomes. Incubation with HMB-45 MoAb was positive in all cell lines. PAL-M2, NK1/C-3, MAAMA, and IND-1 MoAbs stainings were positive with variable intensity. MNF-116 MoAb showed negative staining in the four lines, and S-100 MoAb was also negative except for the UW-1 cell line.

CONCLUSIONS

Human uveal melanoma cell lines OCM-1, SP 6.5, and MKT-BR and the ocular melanocyte cell line UW-1 exhibited maintenance of some structural and ultrastructural characteristics of melanocytic cells. All four MoAbs, PAL-M2, NK1/C3, IND-1, and MAAMA against cutaneous melanoma-associated antigens stained positively all melanoma cell lines as well as the melanocytic cell line, suggesting that in vitro proliferation of melanocytes could modify their antigenic expression.

Prognostic parameters in uveal melanoma: a review

Histologic cell type, largest tumor diameter and tumor location have traditionally been regarded as the leading predictors of survival for uveal melanoma. Morphological cell typing is, however, subjective to variations in interpretation. More objective classification parameters have emerged from extensive cytomorphometrical and DNA flow cytometrical studies. For patients with uveal melanoma there is no effective therapy if metastases have developed, and the median survival after clinical diagnosis of hepatic metastases is extremely poor. Current research focuses on the mechanisms underlying the metastatic process, including tumor vasculature, cytogenetics, oncogene activation, immunology, melanoma-associated antigens and tumor cell migration (cell-cell and cell-matrix interaction). Several new prognostic parameters have emerged from these studies, such as closed vascular patterns, loss of one chromosome 3, and different indices of cell proliferation. Furthermore, considerable genotypical and phenotypical differences have been found between uveal and cutaneous melanoma. In prospective studies on large series of melanomas a combination of histopathological and/or clinical prognostic parameters might be selected with high sensitivity and specificity, providing a way of selecting patients at high risk of developing metastatic disease, who might be eligible for adjuvant therapy.

Metastatic uveal melanoma. A morphologic and immunohistochemical analysis

BACKGROUND

Uveal melanoma often metastasizes late and preferentially to the liver, in contrast to cutaneous melanoma. The objective of the current study was to evaluate the histopathologic and immunohistochemical changes in primary uveal melanomas and their corresponding metastases.

METHODS

The morphology and immunohistochemical reactivity for the melanoma-associated antibodies HMB-45, S-100 protein, and NKI-C3 were assessed for 29 primary uveal melanomas and their corresponding metastatses.

RESULTS

A significant difference in cell type of the primary and the metastatic uveal melanoma was found (P = 0.0001). The metastases derived from the 29 patient's revealed 82.5% epithelioid or nonclassifiable cells. Positive staining of the primary uvea melanomas and their metastases was found to be 93% and 91%, respectively, for HMB-45, 80% and 66%, respectively, for S-100, and 56% and 71%, respectively, for NKI-C3.

CONCLUSIONS

Metastases of uveal melanomas are comprised of a higher grade of malignant cell types. Nonclassifiable cells can be observed in 40% of metastatic lesions. In the current study, HMB-45 proved to be the most sensitive immunohistochemical marker in the analysis of metastatic uveal melanoma and should be used as part of a panel of monoclonal antibodies in the analysis of any metastatic tumor of unknown origin.

Immunoscintigraphy for ocular melanoma: a reliable diagnostic technique?

BACKGROUND

Immunoscintigraphy (IS) has recently been used as a diagnostic tool for ocular melanoma. We wanted to reevaluate published data in our own patients and to correlate immunoscintigraphic results with histologic findings and immunohistochemical characteristics of the tumour tissue.

METHODS

During a 4-year period, IS was performed on 35 patients (average age 64 years) with suspected ocular melanoma by i.v. injection of 225.28S, a monoclonal antibody against high-molecular-weight melanoma-associated antigen. Histology was available in 22 cases. Tumour tissue was evaluated for cell type, vascularization, necrosis, pigmentation, and lymphocytic infiltration, and immunohistochemistry was performed with 225.28S and antibodies against HMB-45, S-100 and vimentin. One hundred and two patients with metastasizing cutaneous melanoma served as controls. In these patients the identical immunoscintigraphic technique was applied.

RESULTS

IS yielded a positive result in about 50% of our patients with ocular melanoma, while in patients with cutaneous melanoma sensitivity was 89%. In five patients who turned out not to have melanoma, two false-positive results were obtained (one subretinal hemorrhage and one Wegener's granulomatosis). No correlation was found between any of the histological features or the immunoreactivity pattern and the immunoscintigraphic outcome. However, antigenic differences between ocular and cutaneous melanoma were evident.

CONCLUSION

We conclude that IS, using the antibody applied in this study, is of only limited value in patients with ocular melanoma. Our results suggest that antigenic differences, rather than histological characteristics or technical problems, are responsible for the low sensitivity in ocular melanoma compared to cutaneous melanoma.

HMB45: a specific marker for melanoma metastases in the central nervous system?

The monoclonal antibody HMB45 is used to detect an epitope specific for melanocytes, malignant melanomas and melanoma metastases. Using the PAP method, we observed consistent expression of HMB45 in 19 metastases of melanotic and amelanotic malignant melanomas of the central nervous system, while metastases of 32 adenocarcinomas, 10 squamous cell and 8 small cell carcinomas were negative except for 2 cases of breast cancer. Differential diagnosis between cancer and melanoma metastases can be made using cytokeratins as an additional immunocytochemical marker protein. Ten meningeomas and 5 pineocytomas were also negative. Even though it is not absolutely specific, we consider the HMB45 immunoreaction diagnostic for a metastasis of a malignant melanoma if the tumour is cytokeratin negative and HMB45 positive in a large number of tumour cells.

Proliferative activity in bilateral paraneoplastic melanocytic proliferation and bilateral uveal melanoma

Images

Are most intraocular "leiomyomas" really melanocytic lesions?

BACKGROUND

Intraocular smooth muscle tumors have long been a subject of controversy. The advent of immunohistochemistry with antibodies against HMB-45, S-100, smooth muscle actin, desmin, and vimentin has helped greatly in the distinction between smooth muscle tumors and melanocytic lesions.

METHODS

Twenty-seven archival tissue blocks from patients who had had intraocular leiomyomas or leiomyosarcomas diagnosed were located and fresh sections cut and stained for the above markers. The cases constituted 24 iris lesions and 3 ciliary body lesions.

RESULTS

All 24 iris tumors were reclassified as iris melanocytic lesions. Two of the three ciliary body leiomyomas retained their classification, and the third was reclassified as a spindle B-cell melanoma.

CONCLUSION

The authors suggest that intraocular leiomyomas are much rarer than previously suggested and that many of the cases previously reported in the literature are open to question.

Rejection of intraocular tumors from transgenic mice by tumor-infiltrating lymphocytes

The present study examined the role of tumor infiltrating lymphocytes (TIL) in the rejection of intraocular tumors from SV40 transgenic mice. Tumor cells from an intraocular tumor arising in an SV40 transgenic FVB/N mouse were transplanted into the eyes of syngeneic FVB/N mice and the TIL isolated. TIL were assessed for direct cytolytic activity in vitro. TIL were also transferred passively to immunosuppressed FVB/N mice to determine if they could mediate intraocular tumor rejection. The role of CD4+ and CD8+ T cells in intraocular tumor rejection was evaluated by depleting the respective cell populations in FVB/N hosts prior to intraocular tumor challenge. The results showed that intraocular tumors undergoing rejection in immunocompetent syngeneic hosts became infiltrated with T cells, with the CD8+ subset predominating at the time of rejection. By contrast, athymic nude mice did not reject the intraocular tumors nor did the tumors become infiltrated with TIL. TIL displayed direct, tumor-specific cytolytic activity immediately after isolation from the tumor-containing eyes. FVB/N hosts depleted of CD4+ T cells were unable to reject their intraocular tumors. In vivo depletion of CD8+ T cells delayed, but did not prevent tumor rejection. Adoptively transferred TIL mediated swift rejection of intraocular tumors in immunoincompetent recipients. Recipients of TIL, but not recipients of normal spleen cells, acquired significant tumor-specific CTL activity that was demonstrable in vitro. The results strongly suggest, but do not prove, that TIL mediate rejection of intraocular tumors from transgenic mice by direct cytolysis. Although CD4+ T cells are necessary for tumor rejection and are capable of direct cytolysis, the predominant effector cells are CD8+ CTL.