- Tumors must be HER2 negative as defined according to ASCO/CAP 2013, as HER2 0 - 1+ by IHC or non-amplified FISH or CISH. If HER2 IHC is 2+, FISH/CISH must be performed and must not be positive (must be a ratio of < 2), but otherwise FISH/CISH is not required if IHC is 0 or 1+ by institutional standards.