DR-257 Somatic mutations and germline variants at Estrogen Receptor / DNA binding sites and their impact on gene expression programs in metastatic breast cancer

Estrogen Receptor is a hormone-responsive protein,  responsible for breast tumor growth. We found that DNA-binding specificity can predict treatment response, and profiled estrogen receptor/DNA interactions in over 100 breast tumors. Now, we aim to determine whether these bound-regions are mutated in breast cancer, and how this impacts tumor biology. For this, we request access to data from the metastatic breast cancers sequenced at the HMF. In metastatatic breast cancer, estrogen receptor remains critically important. We know that this DNA occupancy differs between patients, whether mutations at these sites alter biology is unknown. This information may explain why some tumors are resistant to therapy, and how we can resolve this.

Wilbert Zwart, Netherlands Cancer Institute, the Netherlands