In Vivo HER2-Targeting Specificity for 124I-PIB-ZHER2:342 and 125I-PIB-Trastuzumab
| 124I-PIB-ZHER2:342 | 125I-PIB-trastuzumab | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Time (h) | Location | Nonblocked | Blocked with ZHER2:342 | Blocked with trastuzumab | 125I-PIB-ZTaq: | Nonblocked | Blocked with ZHER2:342 | Blocked with trastuzumab | 125I-PIB-palivizumab |
| 6 | Blood | 0.59 ± 0.05 | 0.5 ± 0.1 | ||||||
| Tumor | 4.7 ± 1.0 | 0.3 ± 0.2 | |||||||
| 24 | Blood | 0.09 ± 0.02 | 0.19 ± 0.01 | 0.16 ± 0.02 | 13 ± 2 | 14 ± 1 | 13 ± 2 | 7.0 ± 0.5 | |
| Tumor | 1.4 ± 0.3 | 0.8 ± 0.1 | 1.9 ± 0.4 | 16 ± 3 | 19 ± 2 | 5.3 ± 0.3 | 1.9 ± 0.1 | ||
Tumor targeting of radioiodinated Affibody molecule and trastuzumab was compared in BALB/c nu/nu mice with NCI-N87 xenografts with that for mice injected in advance with blocking amounts of nonlabeled Affibody molecule (1 h before injection of 124I-PIB-ZHER2:342/125I-PIB-trastuzumab) or trastuzumab (24 h before injection of 124I-PIB-ZHER2:342/125I-PIB-trastuzumab) and unspecific to HER2 Affibody molecule 125I-PIB-ZTaq and 125I-PIB-palivizumab.