TABLE 1.
PSMA Affinities, Internalization, and Lipophilicity of Ga- and Lu-PSMA-I&T (4) and of Respective Unlabeled and Labeled PSMA-I&F Analogs
| Ligand | IC50 (nM) | Corresponding radioligand | Specific internalization (% of reference)* | Lipophilicity (log POW) | Plasma protein binding (%)† |
| PSMA-I&T | 10.2 ± 3.5 | ||||
| Ga-PSMA-I&T | 9.3 ± 3.3 | 68Ga-PSMA-I&T | 206 ± 16 | −4.30 | 52.0 (84.2) |
| Lu-PSMA-I&T | 7.9 ± 2.4 | 177Lu-PSMA-I&T | 114 ± 8 | −4.12 | 78.6 (82.1) |
| PSMA-I&F | 10.3 ± 0.7 | 98.3 | |||
| Ga-PSMA-I&F | 10.5 ± 2.1 | 68Ga-PSMA-I&F | 103 ± 9 | −3.40 | 93.7 (94.0) |
| Lu-PSMA-I&F | 9.6 ± 1.7 | 177Lu-PSMA-I&F | 106 ± 2 | −3.53 | 95.0 (98.9) |
*
Specific internalization (total internalization corrected by internalization in the presence of 10 μM 2-PMPA) of the reference compound (125I-IBA)KuE was determined in the same experiment (dual-tracer study) and used for data normalization. Data represent specific internalization at 1-h incubation time.
†
Numbers represent HSA binding of the nonradioactive compounds determined via chromatography; numbers in parentheses represent plasma protein binding determined using fresh human plasma and the corresponding radiolabeled analogs.