Preparation and bioevaluation of a 99mTc-labeled small-molecular radiotracer for PD-L1 imaging

In this study, a 99m Tc-labeled small molecule imaging probe [ 99m Tc]Tc-PG3C-CBM for PD-L1 imaging was designed. It showed a radiochemical yield of > 97% and good in vitro stability. Uptake in A375-hPD-L1 cells (17.07 ± 1.40%) was 4.5 times higher than in A375 cells (3.81 ± 0.19%). The probe demonstrated moderate PD-L1 affinity (K D : 11.6 ± 2.57 nM; IC 50 : 59.2 ± 2.40 nM). Additionally, SPECT/CT imaging and biodistribution results indicated that [ 99m Tc]Tc-PG3C-CBM was mainly metabolized by the liver and showed some accumulation at the tumor site. These results suggest that [ 99m Tc]Tc-PG3C-CBM could potentially target PD-L1 at tumor sites.