Kidney uptake of antibody fragments iswell-known.33 High kidney uptake has beenobserved in patientsinjected with [68Ga]Ga-DOTA-trastuzumab F(ab')2 for PET imaging of HER2-positive BC.34 An unexpected finding was the rapid elimination of [111In]In-DOTA-trastuzumab IgG from the blood, which decreased threefoldfrom 33.1 ± 4.3% ID/g at 1 h p.i. to 11.0 ± 2.7% ID/g at2 d p.i. and to 0.06 ± 0.02% ID/g at 14 d p.i. (Figure 3). Here, ERBB2 is linked to breast cancer.