Multiplex fluorescence in situ hybridization identifies novel rearrangements of chromosomes 6, 15, and 18 in primary uveal melanoma

New Treatment Horizons in Uveal and Cutaneous Melanoma

Melanoma is a complex and heterogeneous malignant tumor with distinct genetic characteristics and therapeutic challenges in both cutaneous melanoma (CM) and uveal melanoma (UM). This review explores the underlying molecular features and genetic alterations in these melanoma subtypes, highlighting the importance of employing specific model systems tailored to their unique profiles for the development of targeted therapies. Over the past decade, significant progress has been made in unraveling the molecular and genetic characteristics of CM and UM, leading to notable advancements in treatment options. Genetic mutations in the mitogen-activated protein kinase (MAPK) pathway drive CM, while UM is characterized by mutations in genes like GNAQ, GNA11, BAP1, EIF1AX, and SF3B1. Chromosomal aberrations, including monosomy 3 in UM and monosomy 10 in CM, play significant roles in tumorigenesis. Immune cell infiltration differs between CM and UM, impacting prognosis. Therapeutic advancements targeting these genetic alterations, including oncolytic viruses and immunotherapies, have shown promise in preclinical and clinical studies. Oncolytic viruses selectively infect malignant cells, inducing oncolysis and activating antitumor immune responses. Talimogene laherparepvec (T-VEC) is an FDA-approved oncolytic virus for CM treatment, and other oncolytic viruses, such as coxsackieviruses and HF-10, are being investigated. Furthermore, combining oncolytic viruses with immunotherapies, such as CAR-T cell therapy, holds great potential. Understanding the intrinsic molecular features of melanoma and their role in shaping novel therapeutic approaches provides insights into targeted interventions and paves the way for more effective treatments for CM and UM.

Choroidal biopsies; a review and optimised approach

The majority of choroidal tumours are diagnosed accurately with clinical examination and the additional data obtained from non-invasive imaging techniques. Choroidal biopsies may be undertaken for diagnostic clarity in cases such as small melanocytic or indeterminate lesions, identifying the primary tumour in the case of choroidal metastases or the subclassification of rarer conditions such as uveal lymphoma. There is however an increasing use of biopsy techniques for prognostication in uveal melanoma. This review explores the main indications and surgical techniques for tumour acquisition, and the optimised approach utilised by the current authors to improve successful yield for histological and genetic analysis.

Molecular pathology of uveal melanoma

Like other cancers, uveal melanomas (UM) are characterised by an uncontrolled, clonal, cellular proliferation, occurring as a result of numerous genetic, and epigenetic aberrations. Signalling pathways known to be disrupted in UM include: (1) the retinoblastoma pathway, probably as a result of cyclin D1 overexpression; p53 signalling, possibly as a consequence of MDM2 overexpression; and the P13K/AKT and mitogen-activated protein kinase/extracellular signal-related kinase pathway pathways that are disturbed as a result of PTEN and GNAQ/11 mutations, respectively. Characteristic chromosomal abnormalities are common and include 6p gain, associated with a good prognosis, as well as 1p loss, 3 loss, and 8q gain, which correlate with high mortality. These are identified by techniques such as fluorescence in situ hybridisation, comparative genomic hybridisation, microsatellite analysis, multiplex ligation-dependent probe amplification, and single-nucleotide polymorphisms. UM can also be categorised by their gene expression profiles as class 1 or class 2, the latter correlating with poor survival, as do BRCA1-associated protein-1 (BAP1) inactivating mutations. Genetic testing of UM has enhanced prognostication, especially when results are integrated with histological and clinical data. The identification of abnormal signalling pathways, genes and proteins in UM opens the way for target-based therapies, improving prospects for conserving vision and prolonging life.

Genetics of uveal melanoma and cutaneous melanoma: two of a kind?

Cutaneous melanoma and uveal melanoma both derive from melanocytes but show remarkable differences in tumorigenesis, mode of metastatic spread, genetic alterations, and therapeutic response. In this review we discuss the differences and similarities along with the genetic research techniques available and the contribution to our current understanding of melanoma. The several chromosomal aberrations already identified prove to be very strong predictors of decreased survival in CM and UM patients. Especially in UM, where the overall risk of metastasis is high (45%), genetic research might aid clinicians in selecting high-risk patients for future systemic adjuvant therapies.

Molecular cytogenetic analysis of archival uveal melanoma with known clinical outcome

Uveal melanoma (UM) is the most common primary intraocular tumor in the Western world. Cytogenetically, this tumor is characterized by typical chromosomal aberrations such as loss of 1p, 3, and 6q, and gain of 6p and 8q. Routinely, karyotyping and fluorescent in situ hybridization (FISH) on fresh tumor-biopsies are used to identify chromosomal changes. In addition, archival UM samples can be examined using comparative genomic hybridization (CGH). In the presented study, we used CGH on a series of 46 archival uveal melanomas to identify chromosomal changes. In 44 tumors aberrations were present and classic prognostic markers as loss of 1p (12 tumors, 26.1%), monosomy 3 (26 tumors, 56.5%), loss of 6q (10 tumors, 21.7%), and gain of chromosome arm 8q (27 tumors, 58.7%) were observed. Gain of chromosome arms 18q or 21q was found in three UMs. Multiplex ligation-dependent probe amplification (MLPA), a novel technique in UM, was performed to verify this low number of chromosome 18 and 21 abnormalities, but we could not confirm the previously reported gain of 18q11.2 and 21q11.2 as poor prognostic factors in UM.

In vivo monosomy 3 detection of posterior uveal melanoma: 3-year follow-up

BACKGROUND

Monosomy 3 is a highly specific marker for poor prognosis in posterior uveal melanoma. Unfortunately, cytogenetic prognostication is limited to enucleated eyes or resected tumors. The aim of this study was to evaluate mid-term natural history and safety of in vivo detection of chromosome 3 status in posterior uveal melanomas undergoing plaque brachytherapy.

METHODS

A 25-gauge transscleral fine needle aspiration biopsy (FNAB) was performed in 32 eyes affected by posterior uveal melanoma undergoing plaque brachytherapy, just before applying the radioactive plaque. Sampled material underwent fluorescence in situ hybridization (FISH) with centromeric probes for chromosome 3. All patients had a follow-up of at least 36 months.

RESULTS

Mean follow-up was 47.1 +/- 8.5 months. Mean largest basal diameter and mean thickness of the tumors were 12.5 +/- 2.7 mm and 8 +/- 2.3 mm respectively. FNAB yielded sufficient material in 26 of 32 cases (81.2%). Adequacy of the sample ranged from 91.1% (ciliary body tumors) to 76.8% (choroidal tumors). Seventeen cases had monosomy 3 (65.3%). No correlation was found between monosomy 3 and tumor dimensions or location (ciliary body vs choroidal tumors). No early and mid-term local complications were documented. Seven patients (21.8%) died during follow-up: five (15.6%) of them died due to metastatic disease (all had monosomy 3 tumors).

CONCLUSIONS

Posterior uveal melanomas may be adequately and safely sampled, by intra-operative transscleral FNAB, to detect in vivo monosomy 3.