One-Pot Radiosynthesis and Biological Evaluation of a Caspase-3 Selective 5-[^123,125I]iodo-1,2,3-triazole derived Isatin SPECT Tracer.

ABSTRACT: Induction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [¹⁸F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (^123,125I) was achieved in 55?±?12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [¹⁸F]ICMT11 (K_i = 6.1?±?0.9?nM and 12.4?±?4.7?nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.

SUBMITTER: Glaser M 

PROVIDER: S-EPMC6917698 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature