Proline linker in 99mTc PSMA tracers lowers kidney uptake, with early patient imaging
- Researchers built 99mTc-labeled PSMA ligands that use D- or L-proline as a rigid linker, paired with tuned co-ligands, giving hydrophilic complexes that label efficiently and stay stable in vitro.
- The lead tracer, L-M1, bound PSMA-expressing cells well and showed the lowest kidney retention in mice, while still reaching both high- and lower-PSMA tumor models with favorable contrast.
- SPECT/CT matched the biodistribution findings, and an exploratory human study clearly outlined small prostate cancer lesions.
💡 Points
Kidney retention is what kills most 99mTc-PSMA tracers, and a rigid proline linker plus co-ligand tuning attacking it is a sensible handle: conformational restriction presumably tightens the pharmacophore presentation while cutting renal trapping. L-M1 beating its D-isomer analogs on kidney is the SAR I'd chase. Still, mouse kidney differs from human, and the clinical read here is tiny and exploratory.