- ErbB2 gene amplification by FISH/CISH (>6 ErbB2 gene copies per nucleus, or a FISH ratio [ErbB2 gene copies to chromosome 17 signals] of >2.2.) Patients with a negative or equivocal overall result (FISH test ratio of ≤2.2, ≤6.0 ErbB2 gene copies per nucleus) and staining scores of 0,1+, 2+ or 3+ (in 30% or less neoplastic cells) by IHC are NOT eligible for participation in the trial.