RDC Linkers

Radionuclide-drug conjugates (RDCs) integrate a targeting ligand, a radionuclide payload, and a chelator-linker system that connects these functional components while preserving biological targeting and radiochemical stability^[1][2]. Linkers therefore serve as critical structural elements that influence the in vivo performance, biodistribution, clearance profile, and therapeutic index of radiopharmaceutical constructs^[2]. Mechanistically, linker chemistry can be used to modulate interactions with biological systems and to optimize tissue-specific pharmacokinetics, thereby affecting radiation delivery to tumors and normal organs^[2][3]. In oncology-focused RDC development, linker design directly contributes to tumor targeting efficiency because radionuclides must remain associated with the targeting vector during circulation and target engagement^[1][4]. Compared with other conjugate technologies such as antibody-drug conjugates, RDCs place additional emphasis on maintaining radiometal-chelator integrity and controlling radiopharmaceutical disposition under physiological conditions^[2]. Distinct linker architectures, including cleavable and pharmacokinetically engineered designs, have been investigated to improve clearance from non-target tissues and reduce off-target radiation exposure while preserving tumor uptake^[2][3]. For experimental applications, linker optimization has become an important strategy for improving imaging contrast, therapeutic efficacy, dosimetry, and safety, making linker engineering a central component of next-generation RDC and radiopharmaceutical research^[2][3][4].