Evaluation of Rat Acute Phase Proteins as Inflammatory Biomarkers for Vaccine Nonclinical Safety Studies.

The objectives were to characterize the kinetics of acute phase proteins (APPs) α-2 macroglobulin (A2M), α-1 acid glycoprotein (A1AGP), and fibrinogen (FIB), and injection site macroscopic and microscopic findings following intramuscular administration of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (TDaP; Adacel); adjuvants (aluminum phosphate [AlPO4]; aluminum hydroxide, Al[OH]3; CpG/Al[OH]3; or Quillaja saponaria 21 [QS-21]); or saline to female Wistar Han rats. Intravascular lipopolysaccharide (LPS) was a positive control. Injection sites and lymph nodes were evaluated microscopically, using hematoxylin and eosin (H&E) stained sections, 48 hours postdose (HPD) and compared with APP concentrations; A2M and A1AGP were measured using Meso Scale Discovery analyzer. Fibrinogen was measured on STA Compact analyzer. In a time-course study, APP peaked at 24 or 48 HPD. In a subsequent study at 48 HPD, injection site microscopic changes included inflammation and muscle degeneration/necrosis, which was different in severity/nature between groups. The APPs were not increased in rats administered saline, Al(OH)3, or AlPO4. Fibrinogen and A1AGP increased in rats administered CpG/Al(OH)3, QS-21, or TDaP; and A2M increased in rats administered QS-21. Fibrinogen, A2M, and A1AGP increased after LPS administration. Acute phase proteins can be used to monitor inflammatory responses to adjuvants; however, some adjuvants may induce inflammation without higher APPs.

Therapeutic Effects of FGF23 c-tail Fc in a Murine Preclinical Model of X-Linked Hypophosphatemia Via the Selective Modulation of Phosphate Reabsorption.

Fibroblast growth factor 23 (FGF23) is the causative factor of X-linked hypophosphatemia (XLH), a genetic disorder effecting 1:20,000 that is characterized by excessive phosphate excretion, elevated FGF23 levels and a rickets/osteomalacia phenotype. FGF23 inhibits phosphate reabsorption and suppresses 1α,25-dihydroxyvitamin D (1,25D) biosynthesis, analytes that differentially contribute to bone integrity and deleterious soft-tissue mineralization. As inhibition of ligand broadly modulates downstream targets, balancing efficacy and unwanted toxicity is difficult when targeting the FGF23 pathway. We demonstrate that a FGF23 c-tail-Fc fusion molecule selectively modulates the phosphate pathway in vivo by competitive antagonism of FGF23 binding to the FGFR/α klotho receptor complex. Repeated injection of FGF23 c-tail Fc in Hyp mice, a preclinical model of XLH, increases cell surface abundance of kidney NaPi transporters, normalizes phosphate excretion, and significantly improves bone architecture in the absence of soft-tissue mineralization. Repeated injection does not modulate either 1,25D or calcium in a physiologically relevant manner in either a wild-type or disease setting. These data suggest that bone integrity can be improved in models of XLH via the exclusive modulation of phosphate. We posit that the selective modulation of the phosphate pathway will increase the window between efficacy and safety risks, allowing increased efficacy to be achieved in the treatment of this chronic disease. © 2017 American Society for Bone and Mineral Research.

Preclinical Pharmacokinetics, Pharmacodynamics, Tissue Distribution, and Interspecies Scaling of Recombinant Human Coagulation Factor XaI16L.

FXaI16L is a recombinant human FXa variant which is currently being evaluated in the clinic for treating intracerebral hemorrhage. The aim of our studies is to investigate overall pharmacokinetics, pharmacodynamics, and distribution of FXaI16L in preclinical species, and to understand its potential implication in human. Pharmacokinetics of FXaI16L was examined using active site probes and the results showed that FXaI16L displayed fast clearance, low volume of distribution, and a very short plasma resident time in mice, rats, and monkeys. When pharmacodynamics was examined in monkeys, concentration effects of FXaI16L on shortening of active partial prothrombin time and formation of thrombin-antithrombin complex were observed. Furthermore, biodistribution study was conducted in mice using radiolabeled FXaI16L, and showed that 125I-FXaI16L has high plasma protein binding and significant liver and kidney distribution. Human pharmacokinetic prediction for first-in-human dosing was evaluated using allometric scaling, liver blood flow, and a fixed coefficient method, and single species allometric scaling using monkey data was most predictive for human pharmacokinetics of FXaI16L.

Inflammatory Cell Findings in the Female Rabbit Heart and Stress-associated Exacerbation with Handling and Procedures Used in Nonclinical Studies.

Despite the use of rabbits in biomedical research, including regulatory toxicology and cardiovascular studies, little data exist on heart findings in this species. This study was designed to document myocardial findings in female rabbits and the impact of study-related procedures typical for vaccine toxicology studies. One hundred and forty 6- to 8-month-old female New Zealand White rabbits were divided equally into 2 groups, high and low study procedure groups (group 1 and group 2, respectively). All animals received intramuscular (IM) injections of sterile saline every 2 weeks for 5 times and were necropsied 2 days after the final IM injection. Clinical chemistry, hematology, and urinalysis were evaluated. Blood for stress biomarkers (norepinephrine, epinephrine, cortisol, and corticosterone), C-reactive protein, cardiac troponin I, and creatine kinase were collected at time 0 (just before dose administration) and then at 4, 24, and 48 hr after dose administration in group 1 only. Hearts were assessed histologically. Focal to multifocal minimal inflammatory cell infiltrates were common (∼80%), particularly in the left ventricle and interventricular septum, and were similar to the types of infiltrates identified in other laboratory animal species. Additionally, study-related procedures elevated serum stress biomarkers and exacerbated the frequency and severity of myocardial inflammatory cell infiltrates.