biomarkerbiomarker /ˈbæɪəʊˌmɑːk $ -oʊˌmɑrkər/ noun [countable] medical 
a chemical substance in your body, which can show doctors whether you have a particular medical condition, are likely to have it, or whether a treatment is successful: 
The diagnosis of these patients is based on a biomarker.
a chemical substance in your body, which can show doctors whether you have a particular medical condition, are likely to have it, or whether a treatment is successful: The diagnosis of these patients is based on a biomarker.