Table 2.
Binding affinities and Pharmacokinetics of featured first-generation tau PET-tracers.
| Tracer | Log P | Tau Affinity [nM] | Selectivity tau/Aβ | Aβ Affinity (nM) | Brain Uptake [%ID/g] | Brain Clearance [%ID/g] | |
|---|---|---|---|---|---|---|---|
| HITP | AD-PHF, Kd [nM] | 2 min p.i. | 30 min p.i. | ||||
| BF-158 [155] | 1.67 | EC50: 399 | NA | 1.60 1 | Ki: > 5000 | 11.3 | 3.1 |
| BF-170 [155] | 1.85 | EC50: 221 | NA | 3.50 1 | Ki: > 5000 | 9.1 | 0.25 |
| [18F]THK-523 [156,157] | 2.40 | Kd1:1.67 Kd2:21.74 Ki: 59.30 | 86.50 | 10 2 | Kd1 (Aβ fibrils): 20.7 | 2.75 | 1.47 |
| [18F]THK-5105 [157] | 3.03 | Kd1:1.45 Kd2:7.40 Ki: 7.80 | 2.63 | 25 2 | Kd1 (Aβ fibrils): 35.9 | 9.20 | 3.61 |
| [18F]THK-5117 [157] | 2.32 | 10.50 | 5.19 | 30 2 | NA | 6.06 | 0.59 |
| [18F]THK-5351 [164] | 1.5 | NA | 2.9 | NA | NA | NA | NA |
| [11C]PBB3 [172,173] | 3.3 | NA | Kd: 2.55 3 | 48 2 | Kd: 114 3 | 1.92 (1 min p.i.) | 0.11 |
| [18F]Flortaucipir (AV-1451,[18F]T807) [178,191] | 1.67 | NA | 14.6 3 | 25 2 | NA | 4.43 (5 min p.i.)7.5 | 0.620.8 |
| [18F]T808 [179,191] | NA | NA | 22 | 27 2 | NA | 4.9 | 0.4 |
The log P values are the partition coefficient (octanol/water) or log D partition coefficient (octanol/PBS) reported in the respective publications. Selectivity tau vs Aβ: 1 EC50(Aβ)/EC50 (tau), 2 Kd(Aβ)/Kd(tau). NA: data not available. 3 Autoradiographic binding to plaque- and tangle-rich regions in AD brains.