Both the lung and brain metastatic lesions were hypermutated, showing APOBEC signature (32) The alterations noted in these samples were overall similar between the brain and the lung metastases, with the exception of SETD1B (p.Q371*), which was present in the brain metastases and the matched primary breast tumor, but not in the lung metastases. This evidence concerns the gene SETD1B and breast neoplasm.