Vemurafenib/PLX4032, a selective inhibitor of mutant BRAFV600E, constitutes a paradigm shift in melanoma therapy.,Unfortunately, acquired resistance, which unavoidably occurs, represents one major limitation to clinical responses.,Recent studies have highlighted that vemurafenib activated oxidative metabolism in BRAFV600E melanomas expressing PGC1α.,However, the oxidative state of melanoma resistant to BRAF inhibitors is unknown.,We established representative in vitro and in vivo models of human melanoma resistant to vemurafenib including primary specimens derived from melanoma patients.,Firstly, our study reveals that vemurafenib increased mitochondrial respiration and ROS production in BRAFV600E melanoma cell lines regardless the expression of PGC1α.,Secondly, melanoma cells that have acquired resistance to vemurafenib displayed intrinsically high rates of mitochondrial respiration associated with elevated mitochondrial oxidative stress irrespective of the presence of vemurafenib.,Thirdly, the elevated ROS level rendered vemurafenib-resistant melanoma cells prone to cell death induced by pro-oxidants including the clinical trial drug, elesclomol.,Based on these observations, we propose that the mitochondrial oxidative signature of resistant melanoma constitutes a novel opportunity to overcome resistance to BRAF inhibition.
Treatment of uveal (intraocular) melanoma is aimed at prolonging life, if possible conserving the eye and useful vision.,About 50% of patients develop fatal metastatic disease despite successful eradication of the primary intraocular tumour.,The effect of ocular treatment on survival is unknown, because the same survival data from case series can be interpreted in different ways.,Treatment is therefore based on intuition and varies greatly between centres.,Randomised trials of treatment vs non-treatment of asymptomatic tumours are desirable but would be controversial, difficult, expensive and possibly inconclusive.,Strategies for coping with uncertainty are needed to avoid unethical care.