ERBB2 and neoplasm: This composite endpoint provided a similar discrimination power when compared to the model with the three biomarkers: D15 SULmax, % reduction in SULmax, their interaction term, and tumor HER2 protein abundance (c = 0.90), i.e. the addition of HER2 tumor protein abundance, which was the most promising HER2 biomarker in the single prediction model, did not further improve prediction power (Table 3B).