Albumin Binding as a Strategy for Improving Tumor Targeting of Radiolabeled Compounds

Abstract

Radiolabeled compounds have been designed and used for imaging and therapy of cancers that have overexpressed receptors such as SSTR2, PSMA, and HER2 on cell surfaces. Rapid elimination of radiopharmaceuticals from the blood results in a reduction of their efficacy. Rapid renal clearance of radiopharmaceuticals leads to shorter circulation times in the blood and therefore have less tumor accumulation. One of the ways to reduce the clearance rate is using molecules with high binding affinity to blood proteins, including albumin. The binding of small molecule to albumin results in an increase in its molecule size and is associated with a slow rate of kidney clearance. The use of an albumin-binding moiety lengthened the in vivo biological half-life of the albumin-binding moiety-carrying radiopharmaceuticals, resulting in elevated tumor accumulation, although the significant background noise should be noticed. The present review aimed to study the effect of different types of albumin-binding moieties, like Evans blue, iodophenyl-based moiety, palmitic acid, and scaffold protein into molecules, on the pharmacokinetic properties of various radiolabeled compounds in animal and human studies.