- Clinical stage IV invasive mammary carcinoma, ER negative (defined as expression of ER in < 5% cells), PR negative (defined as expression of PR in < 5% cells), HER2 negative [acceptable FDA approved methods of HER2 analysis include IHC (0, 1+), fluorescence in situ hybridization (FISH) with HER2/CEN-17 ratio <2, and/or chromogenic in situ hybridization (CISH)] with HER2/CEN-17 ratio <2, as previously documented by histological analysis.