The genetic basis of uveal melanoma

Clinical practice guidelines for the diagnosis and surveillance of BAP1 tumour predisposition syndrome

BRCA1-associated protein-1 (BAP1) is a recognised tumour suppressor gene. Germline BAP1 pathogenic/likely pathogenic variants are associated with predisposition to multiple tumours, including uveal melanoma, malignant pleural and peritoneal mesothelioma, renal cell carcinoma and specific non-malignant neoplasms of the skin, as part of the autosomal dominant BAP1-tumour predisposition syndrome. The overall lifetime risk for BAP1 carriers to develop at least one BAP1-associated tumour is up to 85%, although due to ascertainment bias, current estimates of risk are likely to be overestimated. As for many rare cancer predisposition syndromes, there is limited scientific evidence to support the utility of surveillance and, therefore, management recommendations for BAP1 carriers are based on expert opinion. To date, European recommendations for BAP1 carriers have not been published but are necessary due to the emerging phenotype of this recently described syndrome and increased identification of BAP1 carriers via large gene panels or tumour sequencing. To address this, the Clinical Guideline Working Group of the CanGene-CanVar project in the United Kingdom invited European collaborators to collaborate to develop guidelines to harmonize surveillance programmes within Europe. Recommendations with respect to BAP1 testing and surveillance were achieved following literature review and Delphi survey completed by a core group and an extended expert group of 34 European specialists including Geneticists, Ophthalmologists, Oncologists, Dermatologists and Pathologists. It is recognised that these largely evidence-based but pragmatic recommendations will evolve over time as further data from research collaborations informs the phenotypic spectrum and surveillance outcomes.

Families with BAP1-Tumor Predisposition Syndrome in The Netherlands: Path to Identification and a Proposal for Genetic Screening Guidelines

Germline pathogenic variants in the BRCA1-associated protein-1 (BAP1) gene cause the BAP1-tumor predisposition syndrome (BAP1-TPDS, OMIM 614327). BAP1-TPDS is associated with an increased risk of developing uveal melanoma (UM), cutaneous melanoma (CM), malignant mesothelioma (MMe), renal cell carcinoma (RCC), meningioma, cholangiocarcinoma, multiple non-melanoma skin cancers, and BAP1-inactivated nevi. Because of this increased risk, it is important to identify patients with BAP1-TPDS. The associated tumors are treated by different medical disciplines, emphasizing the need for generally applicable guidelines for initiating genetic analysis. In this study, we describe the path to identification of BAP1-TPDS in 21 probands found in the Netherlands and the family history at the time of presentation. We report two cases of de novo BAP1 germline mutations (2/21, 9.5%). Findings of this study combined with previously published literature, led to a proposal of guidelines for genetic referral. We recommend genetic analysis in patients with ≥2 BAP1-TPDS-associated tumors in their medical history and/or family history. We also propose to test germline BAP1 in patients diagnosed with UM <40 years, CM <18 years, MMe <50 years, or RCC <46 years. Furthermore, other candidate susceptibility genes for tumor types associated with BAP1-TPDS are discussed, which can be included in gene panels when testing patients.

Cytogenetic results of choroidal nevus growth into melanoma in 55 consecutive cases

Purpose

To investigate the cytogenetic results of choroidal nevus with photographically-documented transformation into choroidal melanoma.

Methods

Retrospective analysis of 55 consecutive patients who underwent fine needle aspiration biopsy (FNAB) for DNA isolation and whole genome array based assay for chromosomes 3, 6, and 8 analysis prior to plaque radiotherapy. Tumors with abnormalities in chromosomes 3 and 8 were considered high-risk for metastasis.

Results

At diagnosis of choroidal nevus the mean patient age was 57 years (median 57, range 10–83 years). All patients were Caucasian and 36 (65%) were female. At the time of nevus diagnosis, the mean tumor basal diameter was 7.4 mm (median 6.5, range 1.5–18.0 mm) and tumor thickness was 2.2 mm (median 2.2, range 0.5–3.9 mm). The mean interval between diagnosis of choroidal nevus and transformation into choroidal melanoma was 58 months (median 42, range 3–238 months). At the time of melanoma diagnosis, the mean tumor basal diameter was 9.7 mm (median 9.0, range 5.0–19.0) and tumor thickness was 3.5 mm (median 3.4, range 1.3–8.1). Cytogenetic analysis of FNAB-isolated melanoma revealed 25 patients (45%) with high-risk and 30 (55%) with low-risk cytogenetic findings. The rate of tumor growth into melanoma was inversely related to high-risk cytogenetic profile (p = 0.03) as those with fast transformation ≤ 1 year showed high-risk in 80% compared to those with slow transformation > 1 year whoshowed high-risk profile in only 38%. Fast transformation into melanoma conferred a relative risk (RR) of 2.116 for high-risk cytogenetic profile, compared to slow transformation.

Conclusions

Choroidal nevus with rapid transformation into melanoma within 1 year is significantly more likely to demonstrate high-risk cytogenetic profile, at risk for metastatic disease, compared to those with slow transformation.

Uveal Melanoma: Identifying Immunological and Chemotherapeutic Targets to Treat Metastases

Uveal melanoma is an intraocular malignancy that, depending on its size and genetic make-up, may lead to metastases in up to 50% of cases. Currently, no therapy has been proven to improve survival. However, new therapies exploiting immune responses against metastases are being developed. The primary tumor is well characterized: tumors at high risk of developing metastases often contain macrophages and lymphocytes. However, these lymphocytes are often regulatory T cells that may suppress immune response. Currently, immune checkpoint inhibitors have shown marked efficacy in multiple cancers (eg, cutaneous melanoma) but do not yet improve survival in uveal melanoma patients. More knowledge needs to be acquired regarding the function of T cells in uveal melanoma. Other therapeutic options are related to the biochemical pathways. Targeting the RAF-MEK-ERK pathway with small molecule MEK inhibitors abrogates the growth of UM cells harboring GNAQ/GNA11 Q209 mutations, suggesting that these aberrant G-protein oncogenes mediate, at least in part, their effect through this hallmark proliferation pathway. Other pathways are also implicated, such as those involving c-Jun and YAP. Further studies may show how interference in the different pathways may affect survival.