Biodistribution data obtained 24 h post-injection revealed a biodistribution pattern similar to 89Zr-DFO, but to further assess 25 as a 89Zr chelator, the authors compared the in vivo pharmacokinetics of [89Zr]Zr-25-N-SUC-trastuzumab, which was prepared using a TFP-mediated approach, and [89Zr]Zr-DFO-trastuzumab using small animal PET/CT in a nude mouse model bearing bilateral BT474 (HER2+) and BT20 (HER2−) human breast cancer xenografts. The gene discussed is ERBB2; the disease is breast cancer.