MRD monitoring typically involves measuring signs of a cancer in order to determine if it is disappearing (progression) or returning (relapse). Typically, this can be facilitated by use of less invasive techniques such as liquid biopsy (ctDNA), to monitor cancer-specific somatic variants. A patient-derived approach to the application of ctDNA-based MRD monitoring starts with a tumor profiling analysis to identify clinically relevant tumor variants that constitute the patient’s genomic profile. Following this, a targeted panel/assay containing a subset of the gene variants can be designed for disease monitoring by detecting presence or absence of circulating tumor (ct)DNA variants in the patient’s blood sample. These patient-derived MRD analyses represent a paradigm shift in disease monitoring, and have been adopted by leading liquid biopsy NGS vendors such as Natera’s Signatera® platform and Archer/Invitae’s Personalized Cancer Monitoring (PCM) assay.