Indium-111-DOTA-biotin

Indium-111-DOTA-biotin is a **radiopharmaceutical imaging agent** used in pretargeted radioimmunotherapy (PRIT) and tumor imaging. The molecule consists of biotin conjugated to the chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), which binds the gamma-emitting radioisotope Indium-111. This compound is designed for use in a **three-step pretargeting strategy**: first, a tumor-targeting antibody conjugated with streptavidin is administered; second, a clearing agent removes circulating antibody-streptavidin from the blood; and third, the radiolabeled biotin is injected, which rapidly binds to the streptavidin at the tumor site. The biotin component binds with high affinity to streptavidin through the biotin-streptavidin interaction. The DOTA-biotin structure features an N-methyl amide linker between the DOTA chelate and d-biotin that is resistant to cleavage by serum biotinidase. Indium-111 is a pure gamma emitter used primarily for imaging and biodistribution studies, while the therapeutic analog uses Yttrium-90. The compound exhibits **rapid clearance from blood through the kidneys** (t1/2 < 15 min) with approximately 90% of the injected dose excreted intact into the urine by 2 hours, minimizing radiation exposure to normal tissues while achieving high tumor-to-blood ratios.

Other names

111In-DOTA-biotinindium In 111-DOTA-biotin111In-DOTA biotin