Purpose To evaluate safety, human radiation dosimetry and optimal imaging time of [89Zr]trastuzumab in patients with HER2-positive breast cancer. Procedures Twelve women with HER2-positive breast cancer underwent [89Zr]trastuzumab-PET/CT twice within 7 days postinjection. Biodistribution data from whole-torso PET/CT images, and organ time-activity curves were created using data from all patients. Human dosimetry was calculated using OLINDA with the adult female model. Results High-quality images and the greatest tumor-to-nontumor contrast were achieved with images performed 5 ± 1 day postinjection. Increased [89Zr]trastuzumab uptake was seen in at least one known lesion in 10 patients. The liver was the dose-limiting organ (retention of ~12% of the injected dose and average dose of 1.54 mSv/MBq. The effective dose was 0.47 mSv/MBq. No adverse effects of [89Zr]trastuzumab were encountered. Conclusion [89Zr]trastuzumab was safe and optimally imaged at least 4 days post-injection. The liver was the dose-limiting organ.

Purified 111Ag was used as a radiotracer to investigate silver loading and release, pharmacokinetics and biodistribution of polyphosphoester-based degradable shell crosslinked knedel-like (SCK) nanoparticles as a comparison to the previously reported small molecule, N-heterocyclic silver carbene complex analogue (SCC1) for the delivery of therapeutic silver ions in mouse models. Biodistribution studies were conducted by aerosol administration of 111Ag acetate, [111Ag]SCC1 and [111Ag]SCK doses directly into the lungs of C57BL/6 mice. Nebulization of the 111Ag antimicrobials resulted in an average uptake of 1.07 ± 0.12% of the total aerosolized dose given per mouse. The average dose taken into the lungs of mice was estimated to be 2.6 ± 0.3% of the dose inhaled per mouse for [111Ag]SCC1 and twice as much dose was observed for the [111Ag]SCKs (5.0 ± 0.3% and 5.9 ± 0.8% for [111Ag]aSCK and [111Ag]zSCK, respectively) at 1 h post administration (p.a.). [111Ag]SCKs also exhibited higher dose retention in the lungs; 62 – 68% for [111Ag]SCKs and 43% for [111Ag]SCC1 of the initial 1 h dose was observed in the lungs at 24 h post administration (p.a.). This study demonstrates the utility of 111Ag as a useful tool for monitoring the pharmacokinetics of silver loaded antimicrobials in vivo.

A novel method for radiolabeling perfluorinated alkyl substances (PFAS) with fluorine 18 has been developed, and after purification, the stability and biological distribution in healthy mice were evaluated. Three PFAS, [ 18 F]PFOA (C8), [ 18 F]PFHxA (C6), and [ 18 F]PFBA (C4), were readily labeled and isolated in average yields between 12 and 31%. The stability of each compound was monitored in 0.1% ammonium hydroxide (NH 4 OH) in methanol, in saline, and in human, mouse, and rat sera. The amount of intact, radiolabeled PFAS was determined by radiometric instant thin layer chromatography and was calculated by the amount of free fluorine 18 observed over time. All compounds were highly stable in 0.1% NH 4 OH in methanol and saline, with <10% defluorination observed after 4 h. Interestingly, each compound had differing affinities for the serum proteins. In vivo biodistribution studies in mice showed uptake in all organs examined, with the highest uptake being exhibited in the liver for both [ 18 F]PFOA and [ 18 F]PFHxA and the stomach for [ 18 F]PFBA. The results of this initial study suggest that this method could be valuable in helping to determine the biological uptake of any PFAS in mammals.

The novel compound, (S)-amino-2-methyl-4-[76Br]-bromo-3-(E)-butenoic acid (BrVAIB, [76Br]5), was characterized against the known system A tracer, IVAIB ([123I]8). [76Br]5 was prepared in a 51% ± 19% radiochemical yield with high radiochemical purity (≥98%). The biological properties of [76Br]5 were compared with those of [123I]8. Results showed that [76Br]5 undergoes mixed amino acid transport by system A and system L transport, while [123I]8 had less uptake by system L. [76Br]5 demonstrated higher uptake than [123I]8 in DBT tumors 1 h after injection (3.7 ± 0.4% ID/g vs 1.5 ± 0.3% ID/g) and also showed higher uptake vs [123I]8 in normal brain. Small animal PET studies with [76Br]5 demonstrated good tumor visualization of intracranial DBTs up to 24 h with clearance from normal tissues. These results indicate that [76Br]5 is a promising PET tracer for brain tumor imaging and lead compound for a mixed system A and system L transport substrate.

No abstract

No abstract