Renal brush border strategy: A developing procedure to reduce renal radioactivity levels of radiolabeled polypeptides

The high and persistent radioactivity levels in the kidney constitute a long-unsettled problem of radiolabeled peptides and low molecular weight (LMW) polypeptides, especially when they are labeled with metallic radionuclides. To address the issue, we proposed an approach to liberate a radiometabolite of urinary excretion from covalently conjugated antibody Fab fragments, used as a representative LMW polypeptide, by the action of enzymes present on the brush border membrane of renal tubules. In this review, The history of our approach, starting from radioiodine to metallic radionuclides such as ¹⁸⁸Re, ^99mTc, ^67/68Ga, and ¹¹¹In, will be briefly described. The future perspective of this approach will also be described.