The Genomic Landscape Of The In Situ To Invasive Ductal Breast Carcinoma Transition Shaped By The Immune System.

Background: The transition from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) is an evolutionary bottleneck where progression occurs only in 30% of patients. Whilst the genetic drivers of this transition remain poorly understood, we have previously shown that immune escape is a key event. In this study, we profile the evolutionary trajectory of matched pure DCIS and IDC in the context of the immune microenvironment. Methods: We have evaluated changes in copy number profiles, mutational profiles, expression and neoantigen load in 6 cases of matched pure DCIS and IDC using exome and RNA sequencing. We have integrated this information with topologic assessment of HE 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-059.