Numerous studies have shown CD8+ TIL to be a predictive biomarker of anti-PD-1 therapy in multiple cancers14-16; however, there is a lack of consensus on the methods for identification and quantification of CD8+ TIL within melanoma and across tumor types between different studies.28,29 Given the role of varying biomarkers in the prediction of response to therapy, it would be beneficial to derive a specific, validated, and cost-effective method for analyzing CD8+ TIL within tumor types. This evidence concerns the gene CD8A and melanoma.