Inferring clonal composition from multiple tumor biopsies

Knowledge about the clonal evolution of each tumor can inform driver-alteration discovery by pointing out initiating genetic events as well as events that contribute to the selective advantage of proliferative, and potentially drug-resistant tumor subclones. A necessary building block to the reconstruction of clonal evolution from tumor profiles is the estimation of the cellular composition of each tumor subclone (cellularity), and these, in turn, are based on estimates of the relative abundance (frequency) of subclone-specific genetic alterations in tumor biopsies. Estimating the frequency of genetic alterations is complicated by the high genomic instability that characterizes many tumor types.