Radiomics Biomarkers correlate with CD8 expression and Predict Immune Signatures in Melanoma Patients

Treatment for metastatic melanoma includes targeted and/or immuno-therapy. Although many patients respond, only a subset have complete response. As late stage patients often have multiple tumours in difficult access sites, non-invasive techniques are necessary for the development of predictive/prognostic biomarkers. PET/CT scans from 52 stage III/IV melanoma patients were assessed and CT image parameters were evaluated as prognostic biomarkers. Analysis indicated patients with high standard deviation or high mean of positive pixels (MPP) had worse progression-free survival (p=0.00047 and p=0.0014, respectively) and worse overall survival (p=0.0223 and p=0.0465, respectively). Whole-exome sequencing showed high MPP was associated with BRAF mutation status (p=0.0389). RNA-sequencing indicated patients with immune 'cold' signatures had worse survival, which was associated with CT biomarker, MPP4 (p=0.0284). Multiplex immunofluorescence confirmed a correlation between CD8 expression and image biomarkers (p=0.0028). Implications: CT parameters have the potential to be cost-effective biomarkers of survival in melanoma, and reflect the tumour immune-microenvironment.