Genetic Abnormalities in Uveal Melanoma

Melanocytic tumours are believed to arise from the neural crest-derived melanocytes. Five to twelve percent of all melanomas are located in the eye, making it, after the skin, the second most common site of melanomas (Egan et al., 1988; Chang et al., 1998). Uveal melanoma is the most common form of primary eye cancer in adults, affecting approximately 7 per million people in the Western world each year (Egan et aI., 1988). In persons over 20 years of age, melanoma is the reported diagnosis in 80% of all primary intraocular cancers. Most uveal melanomas are located in the ciliary body and/or the choroid (23% and 72%, respectively), whereas iris melanomas account for only a small percentage of these tnmours (5%) (Yanoff and Fine, 1989). The majority of iris melanomas consist of non-metastasising lesions and 'Will not be discussed in this thesis. Although less than 2% of uveal melanoma patients have clinically detectable metastases at presentation, 50% of all patients ultimately die of metastases, predominantly located in the liver. The median survival time after discovery of the primary tumour is 6.5 years (McLean, 1993), and peaks between the second and the fourth year (Zimmerman et aI., 1978). The 5, 10 and 15 year survival rates based on tumour related mortality are 72%, 59% and 53% respectively (Gamel et aI., 1993; McLean and Gamel, 1998). As of yet, no effective treatment is available once metastatic disease has developed and the survival time after its diagnosis is limited to two to seven months (Seddon et aI., 1983; Kath et aI., 1993)

Cellular radiosensitivity of primary and metastatic human uveal melanoma cell lines

PURPOSE: To investigate the radiosensitivity of uveal melanoma cell lines by a clonogenic survival assay, to improve the efficiency of the radiation regimen. METHODS: Four primary and four metastatic human uveal melanoma cell lines were cultured in the presence of conditioned medium. After single-dose irradiation (0-12 Gy), colonies were allowed to form for 6 to 14 days. Two cutaneous melanomas cell lines were also tested for comparison. The survival curves were analyzed by the linear quadratic (LQ) model, and the surviving fraction at a dose of 2 Gy (SF(2)), the SF at 10 Gy (SF(10)), the ratio of initial irreparably damaged DNA (alpha-coefficient) to the capacity to repair sublethally damaged DNA (beta-coefficient), and the plating efficiency were calculated. RESULTS: The melanomas displayed a wide range of initial irreparable DNA damage (alpha-component), as well as a capacity for repair of sublethal DNA damage (beta-component), which ultimately resulted in a wide range of alpha/beta ratios. These findings were similar in both primary and metastatic melanomas and were comparable with data obtained from two cutaneous melanomas. CONCLUSIONS: Cell lines obtained from primary and metastatic human uveal melanomas displayed a wide range of radiosensitivity, similar to that published for cutaneous melanomas. Translating these data to the clinical setting indicates that a fractionated dose of 8 to 10 Gy administered in three to four fractions, as currently delivered in many centers, should be sufficient to eradicate tumors of approximately 1 cm(3)

Detection of genetic prognostic markers in uveal melanoma biopsies using fluorescence in situ hybridization

PURPOSE: In uveal melanoma, specific chromosomal abnormalities are known to correlate with the risk of metastases; changes in chromosomes 3 and 8q correlate strongly with a decreased survival of the patient, whereas chromosome 6 abnormalities are associated with a better prognosis. Usual

Chemokine Receptor Expression Pattern Correlates to Progression of Conjunctival Melanocytic Lesions

Purpose: Chemokines play a role in the progression and metastatic spread of both cutaneous and uveal melanomas. The aim of this study was to examine the prognostic value of expression of chemokine receptors CCR7, CXCR4, and CCR10 in conjunctival melanocytic lesions. Methods: In total, 44 conjunctival nevi, 21 cases of primary acquired melanosis (PAM) with atypia and 35 conjunctival melanomas, were included. After immunohistochemical staining for CCR7, CXCR4, and CCR10 the immunoreactive score (IRS) was determined. The findings were correlated for association with melanoma and development of metastasis. For mechanistic evaluation, we used a mouse melanoma metastasis model using two human conjunctival melanoma cell lines, CM2005.1 and CRMM1. Results: All tested chemokines showed a significantly higher expression in conjunctival melanoma than conjunctival nevi. There was a statistically significant difference between the IRS in nevi and PAM with atypia for nuclear IRS in CCR10 (P = 0.03) and both nuclear and cytoplasmic IRS in CXCR4 (P < 0.01 and P = 0.03, respectively); this was also true evaluating the groups PAM with atypia and melanoma all together (P < 0.01). Furthermore, a trend for lower IRS was seen in cases of melanoma without metastasis, with a suggestive pattern of a higher IRS in cases that did develop metastases, supported for CXCR4 using the mouse melanoma metastasis model. Conclusions: Expression of specific chemokines changes during the progression and metastatic spread of conjunctival melanocytic lesions. Differential chemokine profiles may hold prognostic value for patients with conjunctival melanomas and might be considered as a therapeutic target

Metastatic disease in polyploid uveal melanoma patients is associated with BAP1 mutations

PURPOSE. Most of the uvea melanoma (UM) display a near-diploid (normal, ~2N) karyotype with only a few chromosomal changes. In contrast to these simple aberrations 18% of the UM samples show a polyploid character (>2N) and this was associated with an unfavorable prognosis. This study attempts to gain insight in the prognostic value of polyploidy in UM. METHODS. In 202 patients the ploidy status of the UM was determined using cytogenetic analysis, fluorescence-in-situ-hybridization (FISH), multiplex ligation dependent probe amplification (MLPA), and/or single nucleotide polymorphism (SNP) array analysis. Immunohistochemistry was used to determine the BAP1 expression and mutation analyses of BAP1 (coding regions) and the mutation hotspots for the SF3B1, EIF1AX, GNAQ, and GNA11 genes was carried out using Sanger sequencing or whole-exome sequencing. RESULTS. Twenty-three patients had a polyploid UM karyotype (11.4%). Patients with a polyploid tumor had larger tumors (15.61 vs. 13.13 mm, P = 0.004), and more often loss of heterozygosity of chromosome 3 (P ¼ 0.003). No difference in occurrence of mutations between polyploid and diploid tumors was observed for BAP1, SF3B1, EIF1AX, GNAQ, and GNA11. Polyploidy did not affect survival (P = 0.143). BAP1 deficiency was the only significant independent prognostic predictor for patients with polyploid tumors, with a 16- fold increased hazard ratio (HR 15.90, P = 0.009). CONCLUSIONS. The prevalence of mutations in the UM related genes is not different in polyploid UM compared with diploid UM. Moreover, similar to patients with diploid UM, BAP1 mutation is the most significant prognostic predictor of metastasis in patients with polyploid UM

Spliceosome mutations in uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy of the eye. It has a high metastatic potential and mainly spreads to the liver. Genetics play a vital role in tumor classification and prognostication of UM metastatic disease. One of the driver genes mutated in metastasized UM is subunit 1 of splicing factor 3b (SF3B1), a component of the spliceosome complex. Recurrent mutations in components of the spliceosome complex are observed in UM and other malignancies, suggesting an important role in tumorigenesis. SF3B1 is the most common mutated spliceosome gene and in UM it is associated with late-onset metastasis. This review summarizes the genetic and epigenetic insights of spliceosome mutations in UM. They form a distinct subgroup of UM and have similarities with other spliceosome mutated malignancies

Local tumour control and radiation side effects for fractionated stereotactic photon beam radiotherapy compared to proton beam radiotherapy in uveal melanoma

Purpose: To compare the adverse side effects of fractionated stereotactic photon beam radiotherapy (fSRT) with proton beam radiotherapy (PBR) in patients with uveal melanoma (UM). Methods: A retrospective study investigating 306 UM patients treated with fSRT (N=153) by the Rotterdam Ocular Melanoma Study group (ROMS), The Netherlands, between 1999–2014 or with PBR (N=153) at the Royal Liverpool University Hospital and the Clatterbridge Cancer Centre, Bebington, United Kingdom, between 1993–2014. The tumours treated with fSRT were matched with tumours treated with PBR based on sex, left or right eye, TNM classification, posterior margin ≤ or > 3mm of the fovea and of the optic disc. Results: The five-year actuarial rates of tumour recurrence were 4.5% for fSRT and 6.1% for PBR. For fSRT and PBR, the five-year actuarial rates of maculopathy were 14.9% and 12.4%, and for vitreous haemorrhage were 29.4% and 4.7%, respectively. Only vitreous haemorrhage (HR: 0.19, 95% CI: 0.07–0.56) was more common after fSRT compared to PBR. Overall, larger tumours were risk factors for maculopathy and secondary enucleation. Conclusions: Both treatments have excellent local tumour control. In matched groups, vitreous haemorrhage was the only adverse side effect showing a significant difference between groups

Genetics of ocular melanoma: Insights into genetics, inheritance and testing

Ocular melanoma consists of posterior uveal melanoma, iris melanoma and conjunctival melanoma. T

Multi-Modality Analysis Improves Survival Prediction in Enucleated Uveal Melanoma Patients

PURPOSE. Uveal melanoma (UM) is characterized by multiple chromosomal rearrangements and recurrent mutated genes. The aim of this study was to investigate if copy number variations (CNV) alone and in combination with other genetic and clinico-histopathological variables can be used to stratify for disease-free survival (DFS) in enucleated patients with UM. METHODS. We analyzed single nucleotide polymorphisms (SNP) array data of primary tumors and other clinical variables of 214 UM patients from the Rotterdam Ocular Melanoma Study (ROMS) cohort. Nonweighted hierarchical clustering of SNP array data was used to identify molecular subclasses with distinct CNV patterns. The subclasses associate with mutational status of BAP1, SF3B1, or EIF1AX. Cox proportional hazard models were then used to study the predictive performance of SNP array cluster-, mutation-, and clinico-histopathological data, and their combination for study endpoint risk. RESULTS. Five clusters with distinct CNV patterns and concomitant mutations in BAP1, SF3B1, or EIF1AX were identified. The sample’s cluster allocation contributed significantly to mutational status of samples in predicting the incidence of metastasis during a median of 45.6 (interquartile range [IQR]: 24.7–81.8) months of follow-up (P < 0.05) and vice versa. Furthermore, incorporating all data sources in one model yielded a 0.797 C-score during 100 months of follow-up. CONCLUSIONS. UM has distinct CNV patterns that correspond to different mutated driver genes. Incorporating clinico-histopathological, cluster and mutation data in the analysis results in good performance for UM-related DFS prediction