In contrast to our earlier study that showed equivalent tumour growth inhibition for EGFR-targeted and non-targeted 177Lu-labeled AnNPs (Yook et al. 2016a), in this study, non-targeted [177Lu]Lu-DOTA-PEG3K-AuNPs were not as effective as [177Lu]Lu-DOTA-PEG5K-trastuzumab-AuNPs for inhibiting tumour growth and resulted in decreased hematocrit, red blood cell and platelet counts. The gene discussed is EGFR; the disease is neoplasm.