Uveal melanoma (UM), the most common primary intraocular malignancy in adults, remains a disease of major unmet need. Despite effective control of the primary tumour, 40-50% of patients ultimately develop metastatic disease, which is associated with poor survival and limited treatment options. Although the therapeutic landscape is evolving, including tebentafusp for selected patients and PKC-targeted strategies such as Darovasertib alone or in combination with Crizotinib, durable responses remain restricted by primary and acquired resistance. Defining the molecular basis of resistance is therefore critical to extending the benefit of targeted therapies and improving outcomes for patients with metastatic UM.
To model clinically relevant resistance, we generated Darovasertib-resistant (DR) and Darovasertib + Crizotinib-resistant (DCR) derivatives of the UM cell lines MP41 and OMM1.3 using a stepwise dose-escalation approach. Cell proliferation and viability assays showed that DR and DCR cells exhibited greater than 10-fold increases in IC50 relative to parental cells, confirming robust resistance to drug-induced growth arrest and cell death. Resistant cells also displayed reduced suppression of canonical PKC downstream effectors, including DUSP6 and RasGRP3, consistent with attenuation of pathway blockade and adaptive signalling rewiring.
To define the molecular architecture of resistance, we performed RNA sequencing and mass spectrometry-based proteomic profiling of parental, DR and DCR cells treated with or without Darovasertib and Crizotinib. Resistant cells demonstrated distinct baseline transcriptional and proteomic states compared with parental counterparts, indicating substantial remodelling during resistance acquisition. Their responses to treatment were also markedly altered, supporting the emergence of alternative survival programmes and pathway dependencies that may be therapeutically targetable.
Current studies are prioritising and validating candidate resistance-associated pathways identified through integrated transcriptomic and proteomic analyses. These targets will be tested in orthotopic metastatic UM models to determine whether rational combination strategies can restore sensitivity and deepen therapeutic response. Collectively, this work seeks to uncover actionable drivers of resistance to PKC-based therapy and provide a mechanistic framework for the development of next-generation combination treatments for metastatic UM. By identifying vulnerabilities that emerge during therapeutic escape, these studies aim to support more durable, biomarker-informed treatment strategies for patients with advanced UM.