ERBB2 and neoplasm: However, in the phase II/III GATSBY trial, the comparison of T-DM1 and paclitaxel for the second-line treatment of patients with HER2-positive advanced G/GEJ adenocarcinoma failed to show an advantage (mOS 7.9 vs. 8.6 months; P = 0.86) possibly because previously archived tumor tissue was selected for this study to assess HER2 status.