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Table 1 Model parameters

From: Potential and pitfalls of 89Zr-immuno-PET to assess target status: 89Zr-trastuzumab as an example

Parameter Abbreviation Unit Value References
Tumor tissue
 Plasma volume fraction pvf 0.04 [9,10,, 10]
 mAb accessible interstitial volume fraction ivf 0.2 [9, 11, 12]
 Extravasation rate constant kev h−1 0.012 [13, 15]
Target—HER2
 Initial target concentration T0 nM 0–27001 [4, 14]
 Equilibrium binding affinity KD nM 5 [14]
 Target synthesis rate ksyn nM· h−1 kdeg·T0 [14, 16]
 Target degradation rate kdeg h−1 0.19 [14, 16]
 Target-mAb internalization rate kint h−1 0.19 [14, 16]
Input
 Injected Dose of 89Zr-mAb in plasma IDl mg 3 [4]
 Injected Dose of mAb in plasma IDu mg 47 [4]
 Exchange rate (plasma to normal tissue) k1 h−1 0.0722 [4, 5]
 Exchange rate (normal tissue to plasma) k2 h−1 0.1366 [4, 5]
 mAb clearance rate from plasma kcl h−1 0.0083 [4, 5]
Fixed
 Plasma volume (fixed at 3 L) Vp L 3  
 Tumor volume (fixed at 1 mL) Vt L 0.001  
 Body weight (fixed at 80 kg) BW kg 80  
Calculated
 Target concentration T nM   
 Amount of (89Zr-)mAb in plasma Xp,l and Xp,u nmole   
 Amount of (89Zr-)mAb in remainder of body XRob,l and XRoB,u nmole   
 Amount of (89Zr-)mAb in interstitial space Xi,l and Xi,u nmole   
 Fraction of (89Zr-)mAb unbound in ivf fu   
 Amount of residualized 89Zr Xr nmole   
 Concentration of 89Zr in the tumor Ct nM   
 Standardized uptake value SUV   
  1. 1The relation between IHC score and HER2 concentration has been described in literature: IHC 0 < 30 nM, IHC 1 = 30–120 nM, IHC 2 = 120–590 nM, IHC 3 > 590 nM [14]. These numbers reflect estimated expression levels before therapy, when target synthesis and degradation are in balance [14, 16]