Genomic characterization associated with loss of hormone receptorexpression in metastatic breast cancer

The biology behind the switch from HR+ primary BC to TN metastatic relapseis largely unknown. We described that primary tumor grade and Ki67 were higher in tumors withER loss than in ab initio TNBC and outcome of Luminal tumor with triplenegative metastasis was intermediate between concordant LUM-LUM andTN-TN BC.In our study we found that high TILs were associated with worse outcomes intumors with ER loss at metastasis. Our aim is to investigate the genomics underlying this IHC subtypeconversions and if there is a prognostic effect. Moreover, we want to study if these HR+BC express TROP2 before TNmetastatic relapse.