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 | |
mAb accessible interstitial volume fraction | ivf | – | 0.2 | |
Extravasation rate constant | kev | h−1 | 0.012 | |
Target—HER2 | ||||
Initial target concentration | T0 | nM | 0–27001 | |
Equilibrium binding affinity | KD | nM | 5 | [14] |
Target synthesis rate | ksyn | nM· h−1 | kdeg·T0 | |
Target degradation rate | kdeg | h−1 | 0.19 | |
Target-mAb internalization rate | kint | h−1 | 0.19 | |
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 | |
Exchange rate (normal tissue to plasma) | k2 | h−1 | 0.1366 | |
mAb clearance rate from plasma | kcl | h−1 | 0.0083 | |
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 | – |