Pharmacokinetic tissue distribution

Biodistribution studies were conducted to evaluate the uptake and pharmacokinetic distribution of Zirconium-89 labeled hu11B6 ([⁸⁹Zr]hu11B6) in human prostate cancer xenograft and GEM models. Mice received a single 5.55 MBq dose of [⁸⁹Zr]hu11B6 (0.150 mCi of activity on 5–50 μg of protein) or a single 11.1 kBq dose of [²²⁵Ac]hu11B6 (300 nCi on 5 μg antibody) for injection via intravenous tail-vein injection (t = 0 h). Animals (n = 4–5 per group) were euthanized by CO₂ asphyxiation at 4, 48, 120 and 360 h post-injection of [²²⁵Ac]hu11B6; or at 120 and 340 h post-injection of reporter [⁸⁹Zr]hu11B6. Blood was immediately harvested by cardiac puncture. Tissues (including the tumor) were removed, rinsed in water, dried on paper, weighed, and counted on a gamma-counter using a 370–510 KeV window at secular equilibrium. Aliquots (0.020 mL) of the injected activities were used as decay correction standards and background signal was subtracted from each sample. The percentage of injected activit per gram of tissue weight (%IA/g) was calculated for each animal and data plotted as mean ± SD. Statistical analysis of data was performed using Prism software (Graphpad Software Inc, La Jolla, CA).