# Albumin-binder ligands

Source: https://nuclide.cc/technologies/albumin-binder-ligands/  
Nuclide record `albumin-binder-ligands` (Technology). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

Attaching a small chemical 'hook' that grips the body's own albumin protein makes a radioactive drug stay in the bloodstream for longer, so more of it reaches the tumour before it is cleared out through the kidneys.

## Summary

Small-molecule and peptide radioligands (such as PSMA-617) are cleared from the blood within minutes to a few hours, which limits the fraction of injected activity that can diffuse into and bind tumour tissue before excretion. Conjugating an albumin-binding moiety, most commonly a truncated Evans blue (EB) dye derivative or 4-(p-iodophenyl)butyric acid (IPBA/IP), to the targeting ligand allows reversible, non-covalent binding to circulating serum albumin (biological half-life around 19 days), which extends the ligand's effective blood half-life from minutes to several hours without permanently trapping the radionuclide.

In preclinical work, Evans-blue-modified PSMA-617 (EB-PSMA-617) showed markedly extended blood retention compared with unmodified PSMA-617 and produced higher tumour uptake and greater therapeutic efficacy at lower administered activity in mouse models; a single low dose eliminated PSMA-positive tumours in one widely cited study. Albumin-binder chemistry generalises across chelator and radionuclide (86Y/90Y/177Lu-DOTA-EB-PSMA-617; 64Cu-PSMA-CM using an MPA albumin-binding moiety) and across targets (SSTR, GRPR ligands). The main design trade-off is pharmacokinetic: too strong an albumin interaction raises blood and normal-organ (especially bone marrow) dose and can worsen the therapeutic index, so linker length, albumin-binding affinity and total charge are tuned empirically for each ligand; increased kidney or hepatobiliary retention has also been reported for some albumin-binder designs and must be balanced against the gain in tumour dose.

## Fields

- Kind: Technology
- Last checked: 2026-09-22
- Also known as: albumin-binding moiety; Evans blue conjugate; IPBA conjugate
- Tags: chemistry; pharmacokinetics; PSMA
- Principle: A small chemical moiety with affinity for serum albumin (such as a truncated Evans blue dye or 4-(p-iodophenyl)butyric acid) is attached to the radioligand; it binds albumin reversibly, piggy-backing on the protein's long circulating half-life so the ligand stays in the bloodstream, and therefore available to bind the tumour, for hours instead of minutes.
- Since: First albumin-binder radioligand conjugates reported around 2010; PSMA-EB conjugates from 2018

## Sources

- Wang et al.: Single low-dose injection of Evans blue modified PSMA-617 radioligand therapy (Bioconjugate Chem 2018): https://pubs.acs.org/doi/abs/10.1021/acs.bioconjchem.8b00556
- Albumin-binding PSMA ligands: implications for expanding the therapeutic window (J Nucl Med 2019): https://jnm.snmjournals.org/content/60/5/656
- Development of an albumin-based PSMA probe with prolonged circulation, PMC 2020: https://pmc.ncbi.nlm.nih.gov/articles/PMC7773938/

## Connected records

- technologies: [DOTA chelation](https://nuclide.cc/technologies/dota-chelation/), [Radioligand therapy (beta emitters)](https://nuclide.cc/technologies/radioligand-therapy/)
- targets: [PSMA](https://nuclide.cc/targets/psma/)
- isotopes: [Copper-64](https://nuclide.cc/isotopes/cu-64/), [Lutetium-177](https://nuclide.cc/isotopes/lu-177/), [Yttrium-86](https://nuclide.cc/isotopes/y-86/), [Yttrium-90](https://nuclide.cc/isotopes/y-90/)

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