18F-FLT PET Imaging in Patients With Advanced Melanoma

In the current study, advanced positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance (PET/MR) imaging methods will be used to validate our hypothesis that melanoma patients receiving Dual-Immune Checkpoint Blockade (DICB) therapy, who ultimately achieve clinical benefit, will have an increase, or "FLARE", in tumor FLT and/or FDG uptake from baseline, as seen after cycle#1 of treatment, and that after 2 cycles of treatment responders will have a decline in FLT and FDG uptake, in comparison to the patients classified as "non-responders". In addition, alterations in tumor apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (DW/MRI) will be evaluated, expecting after cycle#1: transient reductions in ADC due to lymphocyte proliferation, increased cellularity and restriction of water movement in responding patients, with these patients tumors having increased ADC at 2 cycles into therapy associated with tumor necrosis. This study will evaluate rather early PET imaging with FLT and FDG is a useful imaging biomarker of response to DICB.