Abstract
The aim of this work is to explore 132La as a PET imaging surrogate of 225Ac using a DOTA-based, tumor-targeting alkylphosphocholine (NM600). Methods: 132La was produced on a biomedical cyclotron. For in vivo experiments, mice bearing 4T1 tumors were administered [132La]-NM600, and PET/CT scans were acquired up to 24h post-injection (p.i.). Following the last timepoint, ex vivo tissue distribution was measured to corroborate in vivo PET data. Ex vivo tissue distribution was performed at 4h and 24h p.i. in mice injected with [225Ac]-NM600. Results: PET/CT images showed elevated, persistent [132La]-NM600 uptake in the tumor. Low bone accumulation confirmed the in vivo stability of the conjugate. Ex vivo biodistribution validated the image-derived quantitative data, and the comparison of the [132La]-NM600 and [225Ac]-NM600 tissue distribution revealed similar biodistribution of the two radiotracers. Conclusions: These findings suggest that 132La is a suitable imaging surrogate to probe the in vivo biodistribution of 225Ac radiotherapeutics.
- Copyright © 2020 by the Society of Nuclear Medicine and Molecular Imaging, Inc.