Evaluating Prognostic Biomarkers and Investigating the Therapeutic Potential of Single and Drug Combinations for Metastatic Uveal Melanoma

This thesis research project focuses on investigating prognostic biomarkers and assessing the pre-clinical efficacy of single and drug combinations in the treatment of metastatic uveal melanoma (mUM). Uveal melanoma (UM) is the most common primary intraocular tumour in adults. Resection, radiation therapy, and enucleation are the current first-line UM treatments. However, regardless of the treatment received, metastasis occurs in up to 50% of all UM patients within ten years. Therefore, there is a great need for prognostic biomarkers to identify patients at high risk of developing metastatic disease. The potential of circulating tumour DNA (ctDNA) as a UM prognostic biomarker was investigated. mUM patient plasma samples were used to analyse the potential of ctDNA biomarkers, with a focus on detecting the most common UM mutations, GNAQ Q209L, GNAQ Q209P and GNA11 Q209L using digital droplet PCR (ddPCR). The GNAQ Q209P mutation was detected in one mUM patient. Detection of the GNAQ Q209L mutation was inconclusive due to issues with setting the threshold of detection. An optimised assay and positive mutant control for the GNA11 Q209L mutation were designed. Overall, this study provides preliminary data showing it is possible to detect ctDNA in mUM patients using ddPCR.
The next part of this project focused on investigating drug combinations in pre-clinical models of mUM. Current approved drugs for mUM treatment include systemic treatment with tebentafusp-tebn or isolated hepatic perfusion with melphalan. However, these drugs are only available to a subset of patients and improve survival by only a few months. Darovasertib and crizotinib, which are in phase 2 clinical trials for mUM, 1,4-dihydroxy quininib, a cysteinyl leukotriene receptor 1 (CysLT1) antagonist which inhibits mUM hallmarks, and the novel CysLT1 antagonist PRZ6, identified via a virtual screening campaign, were tested in a mUM cell line. Receptor orphan tyrosine kinase 1 (ROR1) was identified as a potential UM therapeutic target through CRISPR screening. This led to testing of zilovertamab, a ROR1 antagonist, in a mUM cell line. The results show that darovasertib, crizotinib, both alone and in combination, and 1,4-dihydroxy quininib significantly reduce mUM cell metabolic activity and viability, while PRZ6 and zilovertamab did not affect mUM cell metabolic activity or viability. Overall, the results indicate that darovasertib, crizotinib and 1,4-dihydroxy quininib in combination have potential as a treatment for mUM.