Differences in the Renal Accumulation of Radiogallium-Labeled (Glu) 14 Peptides Containing Different Optical Isomers of Glutamic Acid.

Acidic amino acid peptides have a high affinity for bone. Previously, we demonstrated that radiogallium complex-conjugated oligo-acidic amino acids possess promising properties as bone-seeking radiopharmaceuticals. Here, to elucidate the effect of stereoisomers of Glu in Glu-containing peptides [(Glu) 14 ] on their accumulation in the kidney, the biodistributions of [ 67 Ga]Ga- N , N '-bis-[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine- N , N '-diacetic acid-conjugated (l-Glu) 14 ([ 67 Ga]Ga-HBED-CC-(l-Glu) 14 ), [ 67 Ga]Ga-HBED-CC-(d-Glu) 14 , [ 67 Ga]Ga-HBED-CC-(dl-Glu) 14 , and [ 67 Ga]Ga-HBED-CC-(d-Glu-l-Glu) 7 were compared. Although the accumulation of these compounds in the bone was comparable, their kidney accumulation and retention were strikingly different, with [ 67 Ga]Ga-HBED-CC-(d-Glu-l-Glu) 7 exhibiting the lowest level of kidney accumulation among these compounds. Repeated d- and l-peptides may be a useful method for reducing renal accumulation in some cases.