ERBB2 and neoplasm: Nonetheless, the tumour uptake in NRG mice with s.c. 164/8-1B/H2N.luc + HER2-positive BC xenografts was > twofold significantly higher (P < 0.0001) in mice co-injected with [111In]In-DOTA-trastuzumab and [225Ac]Ac-DOTA-trastuzumab than in mice coinjected with [111In]In-DOTA-IgG1 and [225Ac]Ac-DOTA-IgG1 (10.6 ± 0.6% ID/g vs. 4.3 ± 0.7% ID/g, Fig. 5a), demonstrating HER2-specific tumour uptake.