The uPath software with the uPath HER2 (4B5) algorithm helps with the quantitative assessment of HER2 (4B5) protein expression in IHC stained FFPE neoplastic breast tissue slides. Whether they are stained or unstained, the uPath HER2 (4B5) algorithm counts the total number of target tumor cells and stratifies the tumor cells. Stain intensity and completeness of membrane staining is how stained cells are stratified. The uPath HER2 (4B5) algorithm combines percent stained (stained, unstained), stain intensity (weak, moderate, strong) and stain completeness (unstained, partial, complete) to generate an HER2 score on a scale of 0–3+. The uPath HER2 (4B5) algorithm reports the HER2 score for both ROI and an aggregate score for all selected ROIs on that slide.