For a clinically HER2-positive tumor (IHC3), tumor uptake increases over time, as no equilibrium is reached between the concentrations of unbound 89Zr-mAb in plasma and in interstitial space (Fig. 3a; model output is based on the values in Table 1, with T0 = 2700 nM, solid line). Here, ERBB2 is linked to neoplasm.