They announced on 16 December 2021 that they would use CTC presence, their ER and HER2 protein status and ERBB2 amplification presence, as well as the CNV, SNV, fusion and microsatellite instability analysis and tumor mutational burden quantification in cfDNA, called ‘DefineMBC’, to classify the different BC subtypes and enable therapy guidance. Here, ESR1 is linked to breast cancer.