Table 2.

Technologies for detection and characterization of ctDNA

Underlying technologyMutation detection approachType of alterationExample alterationsSelected references
Real-time or endpoint PCRARMS-Scorpion PCRKnown point mutationsKRAS, EGFR hotspot changes74
PCR-SSCP73
Mutant allele–specific PCR75
Mass spectrometry68
Bi-PAP amplification76
Digital PCRBEAMingKnown point mutationsKRAS, EGFR hotspot changes78
Droplet-based digital PCR80
Digital droplet PCR79
Gene sequencingSafeSeqsPoint mutations in gene regionsPIK3CA, EGFR, TP53 coding mutations81
OnTarget83
TamSeq82
Whole-genome sequencingDigital karyotypingGenome-wide copy-number changesPersonalized amplifications87, 88, 108, 115
Whole-genome sequencingPAREGenome-wide rearrangementsPersonalized rearrangements85, 86, 88
Targeted sequencingDigital karyotyping/PAREStructural alterations in gene regionsMET, ERBB2 amplification88, 98, 108

Abbreviations: SSCP, single-strand conformational polymorphism; BEAM, Beads, Emulsions, Amplification, and Magnetics; PARE, Personalized Analysis of Rearranged Ends.