AV7909 is a next-generation anthrax vaccine under development for post-exposure prophylaxis following suspected or confirmed Bacillus anthracis exposure, when administered in conjunction with the recommended antibacterial regimen. AV7909 consists of the FDA-approved BioThrax® vaccine (anthrax vaccine adsorbed) and an immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide adjuvant, CPG 7909. The purpose of this study was to evaluate the potential systemic and local toxicity of AV7909 when administered via repeat intramuscular injection to the right thigh muscle (biceps femoris) to male and female Sprague Dawley rats. The vaccine was administered on Days 1, 15, and 29 and the animals were assessed for treatment-related effects followed by a 2-week recovery period to evaluate the persistence or reversibility of any toxic effects. The AV7909 vaccine produced no apparent systemic toxicity based on evaluation of clinical observations, body weights, body temperature, clinical pathology, and anatomic pathology. Necrosis and inflammation were observed at the injection sites as well as in regional lymph nodes and adjacent tissues and were consistent with immune stimulation. Antibodies against B. anthracis protective antigen (PA) were detected in rats treated with the AV7909 vaccine, confirming relevance of this animal model for the assessment of systemic toxicity of AV7909. In contrast, sera of rats that received saline or soluble CPG 7909 alone were negative for anti-PA antibodies. Overall, 3 intramuscular immunizations of Sprague Dawley rats with AV7909 were well tolerated, did not induce mortality or any systemic adverse effects, and did not result in any delayed toxicity.

Evaluation of the AV7909 Anthrax Vaccine Toxicity in Sprague Dawley Rats Following Three Intramuscular Administrations.

The novel potassium competitive acid blocker, KFP‐H008, developed to overcome the shortcomings of proton pump inhibitors. In this study, KFP‐H008 was administered by oral gavage at doses of 0 (control), 15, 45, and 150 mg/kg to Sprague–Dawley rats (24 animals per sex per group). Body weight, food consumption, mortality, sexual cycle, mating behavior, pregnancy, sperm motility, and relative organ weights were evaluated. In a concomitant toxicokinetic (TK) study (10 animals per sex per group), plasma TK parameters and tissue distribution of KFP‐H008 were tested. There were obvious effects at the dosage of 150 mg/kg to male rats with decreases of prostate weight and lower weight gain; to female rats with lower weight gain, hair off, and lower corpus luteum count. There were no effects on litter parameters. Time to reach maximum plasma concentrations for KFP‐H008 was between 0.5 and 1.0 hr for the 15 and 45 mg/kg groups, while for the 150 mg/kg group it had a delay to 2 hr. Overall, the NOAEL of KFP‐H008 was considered to be 45 mg/kg in both genders and the TK study shows that exposure (area under the curve) of male rats was about 1,091.0 ± 530.8 μg/Lhr and to female rats was 1,030.5 ± 512.5 μg/Lhr. Administration of KFP‐H008although reaches the reproductive organs, it demonstrated no significant effects on reproductive organs, it did not affect mating, fertility, pregnancy, growth, or morphologic development.

Fertility and early embryonic development toxicity and toxicokinetic study of KFP‐H008 in Sprague–Dawley rats

The AV7909 vaccine, consists of the Anthrax Vaccine Adsorbed (AVA) bulk drug substance and the immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide adjuvant CPG 7909. The purpose of this research was to evaluate the potential maternal, reproductive, and developmental toxicity of AV7909 in rats to support licensure for use in women of childbearing potential. Groups of first generation (F0 ) female Sprague Dawley rats were dosed by intramuscular injection with water for injection, adjuvant or AV7909 at a volume of 0.5 ml/dose. Each rat received three vaccinations: 14 days prior to start of the mating period, on the first day of the mating period and on gestation day (GD) 7. There was no maternal mortality. Body weights, weight gain, and food consumption were comparable between groups. Findings in F0 females were limited to transient injection site edema and nodules consistent with immunostimulatory effects of the vaccine and adjuvant. Administration of AV7909 did not affect mating, fertility, pregnancy, embryo-fetal viability, growth, or morphologic development, parturition, maternal care of offspring or postnatal survival, growth, or development. There was no evidence of systemic inflammation in pregnant rats, based on evaluation of serum concentrations of the acute phase proteins alpha-2-macroglobulin and alpha-1-acid glycoprotein on GD 21. Anthrax lethal toxin-neutralizing antibodies were detected in AV7909-vaccinated F0 females. The antibodies were also detected in the sera of fetuses and F1 pups. Exposure of the fetuses and pups to maternally derived anthrax lethal toxin-neutralizing antibodies was not associated with developmental toxicity.

Developmental and reproductive safety evaluation of AV7909 anthrax vaccine candidate in rats.

AV7909 is a next-generation anthrax vaccine candidate indicated for post-exposure prophylaxis of exposure to Bacillus anthracis. AV7909 consists of the Anthrax Vaccine Adsorbed (AVA) bulk drug substance and the immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide adjuvant, CPG 7909. Safety testing for pediatric population is warranted to support the potential emergency use of AV7909 in children. This study was conducted to investigate the local tolerance and potential systemic toxicity and their reversibility in juvenile rats by repeat intramuscular injections of the AV7909 vaccine candidate. Animals were dosed on postnatal day (PND) 21 (at weaning), PND 28, and PND 35, with the test article (AV7909), the adjuvant alone (Alhydrogel + CPG 7909), or sterile water for injection. Core group animals were necropsied on PND 37 and recovery group on PND 49. Study end points included survival, clinical observations, injection site observations, body weights, clinical pathology (hematology, coagulation, and clinical chemistry), pro-inflammatory biomarker analysis (alpha-2 macroglobulin [A2M] and alpha-1 acid glycoprotein [AGP]), and anatomic pathology. Immune response to vaccination was measured using the high-throughput anthrax lethal toxin neutralization assay (htpTNA). The AV7909 vaccine candidate produced no apparent systemic or local toxicity. The AGP and A2M levels were elevated in both the adjuvant-alone and AV7909 groups at the end of treatment but were comparable to control levels by the end of the recovery period. All animals in the AV7909 group demonstrated a robust neutralizing antibody response. The results indicate that AV7909 has a favorable safety profile in juvenile rats.

Jeff D Ballin

Papers

Developmental and reproductive safety evaluation of AV7909 anthrax vaccine candidate in rats.

Repeat Dose Toxicity Study of the AV7909 Anthrax Vaccine Candidate in Juvenile Rats.