Uveal melanoma: evidence for adjuvant therapy

Immunoexpression of Macroh2a in Uveal Melanoma

MacroH2A is a histone variant whose expression has been studied in several neoplasms, including cutaneous melanomas (CMs). In the literature, it has been demonstrated that macroH2A.1 levels gradually decrease during CM progression, and a high expression of macroH2A.1 in CM cells relates to a better prognosis. Although both uveal and cutaneous melanomas arise from melanocytes, uveal melanoma (UM) is biologically and genetically distinct from the more common cutaneous melanoma. Metastasis to the liver is a frequent occurrence in UM, and about 40%–50% of patients die of metastatic disease, even with early diagnosis, proper treatment, and close follow-up. We wanted to investigate macroH2A.1 immunohistochemical expression in UM. Our results demonstrated that mH2A.1 expression was higher in metastatic UM (21/23, 91.4%), while only 18/32 (56.3%). UMs without metastases showed mH2A.1 staining. These data could suggest a possible prognostic role for mH2A.1 and could form a basis for developing new pharmacological strategies for UM treatment.

Tumour Expression of Histone Deacetylases in Uveal Melanoma

Purpose

To determine the expression of histone deacetylase enzymes in uveal melanoma tumour cells.

Procedures

This is an observational immunohistochemical study of 16 formalin-fixed, paraffin-embedded eyes enucleated for uveal melanoma between January 2001 and March 2002. Haematoxylin and eosin paraffin sections were reviewed for histopathological parameters according to the American Joint Committee on Cancer 7th edition. Sections were then immunohistochemically stained for histone deacetylases 1, 2, 3, 4 and 6 and sirtuin 2 using an automated Leica Bond II platform and Fast Red chromogen, then digitally scanned using Aperio software before assessment of staining.

Results

Nuclear expression of histone deacetylases 1, 2, 3, 4 and 6 and of sirtuin 2 was confirmed in uveal melanoma tumour cells. In addition, the tumour cells showed cytoplasmic expression of histone deacetylases 4 and 6 and sirtuin 2. Nuclear and cytoplasmic immunostaining was also seen in intraocular tissues uninvolved by the tumour.

Conclusion

Uveal melanoma tumour cells express histone deacetylases 1, 2, 3, 4 and 6 and sirtuin 2, confirming potential tissue targets for histone deacetylase inhibitors.

Uveal Melanoma: A Review of the Literature

Melanomas affecting different components of the uvea occur with differing frequencies and clinical presentations. Uveal melanoma is diagnosed via funduscopic exam and ancillary tests. These lesions may present with visual findings or incidental findings on physical exam. Metastasis occurs in approximately half of all patients with primary uveal melanoma. The liver is the most common site of metastasis. Enucleation was at one time considered the definitive local treatment for primary uveal melanoma, but has been largely replaced by other therapeutic procedures that aim to prevent metastasis while preserving vision. Unfortunately, metastasis of uveal melanoma almost always proves to be fatal. The current treatment of metastatic uveal melanoma is limited by the intrinsic resistance of uveal melanoma to conventional systemic therapies. Advancements in molecular biology have resulted in the identification of a number of promising prognostic and therapeutic targets. Early detection and therapy are important factors in disease survival. It is imperative that the treating physician be familiar with the clinical features of uveal melanoma and distinguish it from mimickers in order to ensure effective and timely treatment.

Genetic prognostication in uveal melanoma

Uveal melanoma (UM) is a rare tumour with a high propensity to metastasize. Although no effective treatment for metastases yet exists, prognostication in UM is relevant for patient counselling, planning of follow-up and stratification in clinical trials. Besides conventional clinicopathologic characteristics, genetic tumour features with prognostic significance have been identified. Non-random chromosome aberrations such as monosomy 3 and gain of chromosome 8q are strongly correlated with metastatic risk, while gain of chromosome 6p indicates a low risk. Recently, mutations in genes such as BAP1, SF3B1 and EIF1AX have been shown to be related to patient outcome. Genetics of UM is a rapidly advancing field, which not only contributes to the understanding of the pathogenesis of this cancer, but also results in further refinement of prognostication. Concomitantly, advances have been made in the use of genetic tests. New methods for genetic typing of UM have been developed. Despite the considerable progress made recently, many questions remain, such as those relating to the reliability of prognostic genetic tests, and the use of biopsied or previously irradiated tumour tissue for prognostication by genetic testing. In this article, we review genetic prognostic indicators in UM, also comparing available genetic tests, addressing the clinical application of genetic prognostication and discussing future perspectives for improving genetic prognostication in UM.