Roadmap from discovery to clinical implementation for candidate biomarkers in the TME in CHL. This diagram shows the path from discovery of candidate biomarkers through to assays suitable for broad clinical implementation. Examples of candidates emanating from targeted discovery approaches and the de novo approaches are shown. Although not absolutely required, several studies have incorporated an internal validation, which increases confidence that the biomarker assay will validate in other cohorts and laboratories: the external validation. Increasingly, biomarker assay development and validation are being performed using material from clinical trials either retrospectively in prospectively collected biopsies or in a prospective fashion.