TABLE 2.
Overview of Currently Available Preclinical Checkpoint Imaging Studies (for PD-1, CTLA-4, and LAG-3)
| Targeting molecule | Radioisotope | Chelator | Animal model | Tumor model | Accumulation time | Study |
| PD-1 | ||||||
| Anti-PD-1 antibody | 64Cu | DOTA | Foxp3+ LuciDTR4 mice | B16F10 | 48 h | (71) |
| Anti-PD-1 antibody | 64Cu | NOTA | C57BL/6 mice | B16F10 | 24 h | (55) |
| Nivolumab | 89Zr | DFO | Cynomolgus nonhuman primates | — | 1, 4, 6, 8 d | (72) |
| Nivolumab | 89Zr | Df | NSG mice | A549 | 3, 6, 12, 24, 48, 72, 168 h | (73) |
| Pembrolizumab | 89Zr | Df | ICR (CD-1), SCID, and NSG mice and Sprague–Dawley outbred rats | — | 0.5, 6, 12, 24, 48, 72, 120, 168 h | (74) |
| Pembrolizumab | 89Zr, 64Cu | DOTA | NSG mice | A375 | 1, 4, 18, 24, 48, 72, 96, 120, 144 h | (75) |
| CTLA-4 | ||||||
| Ipilimumab | 64Cu | DOTA | Athymic nude mice | A549, H358 | 48 h | (22) |
| Ipilimumab and F(ab′)2 fragment of ipilimumab | 64Cu | NOTA | Humanized NBSGW mice | — | 0.5, 3, 12, 24, 48 h | (77) |
| LAG-3 (fully human antibody REGN3767) | 89Zr | DFO | Immunodeficient mice | MC38 | 6 d | (78) |