PET in vivo generators 134Ce and 140Nd on an internalizing monoclonal antibody probe

The in vivo-generator radionuclides Nd-140 (t(1/2) = 3.4 d) and Ce-134 (t(1/2) = 3.2 d) were used to trace a urokinase-type plasminogen activator (uPA)-targeting mouse monoclonal antibody, ATN-291, in U87 MG xenograft tumor-bearing mice. ATN-291 is known to internalize on the uPA/uPA-receptor pair, making it an appropriate targeting vector for investigating the fate of in vivo generator daughters on internalizing probes. Ante-mortem and post-mortem PET imaging at 120 h post-injection gave no indication of redistribution of the positron emitting daughter nuclides La-134 and Pr-140 from tumor tissue (p > 0.5). The lack of redistribution indicates that the parent radionuclides Ce-134 and Nd-140 could be considered as long-lived PET-diagnostic matches to therapeutic radionuclides like Lu-177, Tb-161 and Ac-225 when internalizing bioconjugates are employed.

Automated summary

This study used radiotracers to investigate the behavior of antibody ATN-291 in mice, and found no redistribution of radiotracers in tumor tissue, indicating that Nd-140 and Ce-134 could be potential PET-diagnostic matches for therapeutic radionuclides.