Pharmacokinetics, Biodistribution And Excretion Of A Recombinant Fusion Protein RhTNT-IL-2

Objective: To investigate the preclinical pharmacokinetics, bioditribution and excretion of a recombinant fusion protein rhTNT-IL-2, which is helpful for the investigation of its preclinical toxicology, preclinical pharmacodynamics and clinical experiment.Methods: (1) The pharmacokinetics, bioditribution and excretion of rhTNT-IL-2 were investigated with radiolabels combined with Trichloroacetic acid (TCA) precipitation or single photon emission computed tomography (SPECT). (2) rhTNT-IL-2 were labeled with ¹²⁵I by Chloramine-T (Ch-T) method. Paper chromatography and high performance liquid chromatography (HPLC) were used to determine their radiochemical purities. TCA precipitation method was used to separate the fusion protein from its metabolite, and radioactivity of all samples was counted by a dual-window gamma counter. (3) Wistar rat and macaque were used in the trial. A group of Wistar rats and macaques were injected with ¹²⁵I-rhTNT-IL-2 at 2500μg·kg^-1, 250μg·kg^-1, 125μg·kg^-1and 1250μg·kg^-1, 125μg·kg^-1, 63μg·kg^-1 respectively. After the injection, serial blood samples were withdrawn and determinated. The blood clearance rates of ¹²⁵I-rhTNT-IL-2 were illustrated as its concentration over time. The main parameters of pharmacokinetics were calculated by DAS1.0 software. (4) The biodistribution of ¹²⁵I-rhTNT-IL-2 in rat was determinated by detecting the radioactivity of their organs, and that in macaque was determinated with SPECT and region of interest (RIO) technique. (4) The urine and feces of administrated rats and macaques were collected during a certain interval and radioactivity of aliquot urine and feces was counted. The cumulated excretion fractions of rats and macaques were calculated.Results: (1) The radiochemical purities of ¹²⁵I-rhTNT-IL-2 were more than 95%. There is no change of its character after labeled with iodine-125. (2) The precision of...