ERBB2 and cancer: These were defined as tumors with an IHC score of 1 or 2 and negative FISH results, indicating low HER2 expression withoutERBB2amplification.(6) Those that were once recognized as HER2 negative are now eligible for targeted HER2 therapy, such as antibody-drug conjugates (ADCs), thereby expanding the portfolio of anti-cancer treatment options for these types of tumors.(7)