ERBB2 and cancer: Tracer uptake was observed in 86.7% (15 patients) of primary tumours (SUVmean: 0.7–11.8).180 The first clinical evaluation of 18F-fluorinated anti-HER2 nanobodies ([18F]AlF-RESCA-MIRC213, Kd: 1.23 ± 0.58 nM) for HER2-positive cancer PET/CT imaging in patients was reported by Qin et al. Tumour uptake of [18F]AlF-RESCA-MIRC213 in HER2-positive patients (SUVmax: 3.62 ± 1.56) was significantly greater than that in HER2-negative patients (SUVmax: 1.41 ± 0.4) at 2 h post-injection.181 VHH1 is a single-domain antibody.