The investigators collected 340 plasma samples from 144 clinically annotated patients with detailed clinical data. All plasma samples were already analyzed by plasma-Seq, an approach, which measures copy number from sequence read depth, for a first evaluation of somatic copy number alterations (SCNAs). As this project represents a feasibility study, the investigators want to evaluate to what extend cis-acting alterations can be determined, i.e. establish the corresponding gene expression changes via nucleosome position mapping as previously published by our group. The results will be corroborated by analyses of the corresponding primary tumor by SCNA-seq and RNA-seq.
From the 340 plasma samples the investigators selected 59 as representative for being either luminal (i.e. those with amplifications at 17q23, 11q13/q14, 8p12, 8q, and gains of 16p and 1q; n=25), basal (i.e. gains of 8q, 10p, 12p and various amplifications occurring due to the high-genomic instability; n=25), and ERBB2/HER2 (i.e. high-level amplification on 17q, centered and including the HER2 gene; n=9). These samples will be sequenced with high coverage (70x) so that both mutations and nucleosome positions can be extracted from the obtained sequences.
