DOTA-chelated lanthanide radiometal complexes (Ln-DOTA)

DOTA-chelated lanthanide radiometal complexes are a class of radiopharmaceuticals used for both diagnostic imaging and targeted radionuclide therapy, a concept known as theranostics [1.2.1, 1.3.4]. These complexes consist of a macrocyclic chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), which forms highly stable coordination compounds with trivalent lanthanide ions such as Lutetium-177, Terbium-161, and Gadolinium-157 [1.1.1, 1.3.1]. When conjugated to a targeting moiety like a peptide or antibody, they selectively bind to overexpressed receptors on tumor cells, such as somatostatin receptors or prostate-specific membrane antigen [1.3.1, 1.3.2]. The therapeutic effect is achieved through the emission of ionizing radiation (e.g., beta particles or Auger electrons) that induces lethal DNA double-strand breaks in the vicinity of the target [1.1.2, 1.3.1]. These complexes are valued for their high thermodynamic stability and kinetic inertness, which minimize the release of toxic free metal ions in vivo [1.1.1, 1.1.5]. Clinical safety is primarily limited by the off-target accumulation of the complexes in organs like the kidneys and bone marrow, which can lead to dose-limiting toxicities [1.1.2, 1.3.4].

Other names

Lanthanide-DOTA complexesRadiolanthanide-DOTA bioconjugatesDOTA-lanthanide chelatesLn-DOTA complexes

These complexes function by delivering a radioactive lanthanide isotope to specific biological targets via a conjugated targeting vector. The DOTA chelator ensures high thermodynamic stability and kinetic inertness, preventing the release of toxic free metal ions. Upon binding to target receptors (e.g., SSTR2 or PSMA), the radionuclide emits ionizing radiation (beta particles, alpha particles, or Auger electrons) that induces DNA double-strand breaks and subsequent cell death.