Prevention of Immune Responses to Human Erythropoietin in Cynomologus Monkeys (Macaca fascicularis)

Neonatal Immune Tolerance Induction to Allow Long-Term Studies With an Immunogenic Therapeutic Monoclonal Antibody in Mice

The purpose of this study is to test the feasibility of neonatal immune tolerance induction in mice to enable long-term pharmacokinetic studies with immunogenic therapeutic monoclonal antibodies (mAb). Neonatal immune tolerance was induced by transfer of a mAb to neonatal mice via colostrum from nursing mother mice treated with two subcutaneous doses of a tolerogen starting within the first 24 h after delivery. Adalimumab and efalizumab were administered as tolerogens at various dose levels. Tolerance induction was evaluated in the offspring after reaching adulthood at 8 weeks of age. After a single intravenous injection of the same mAb as used for tolerance induction, the pharmacokinetics of the mAb and formation of anti-drug antibodies (ADA) in plasma were assessed using ELISA. Tolerance induction to adalimumab was achieved in a maternal dose-dependent manner. Adalimumab immune-tolerant offspring showed a slower adalimumab clearance (4.24 ± 0.32 mL/day/kg) as compared to the control group (12.09 ± 3.81 mL/day/kg). In the control group, accelerated clearance started 7 days after adalimumab dosing, whereas immune-tolerant offspring showed a log-linear terminal concentration-time course. In the offspring, the absence of predose ADA levels was indicative of successful tolerance induction. The second test compound efalizumab was not immunogenic in mice under our experimental conditions. Overall, the present study demonstrated the suitability of neonatal immune tolerance induction for a 4-week single dose study in adult mice with a human therapeutic mAb that is otherwise immunogenic in laboratory animals.

Erythropoiesis Equivalence, Pharmacokinetics and Immune Response following Repeat Hematide™ Administration in Cynomolgus Monkeys

Hematide™ is a synthetic PEGylated peptidic erythropoiesis stimulating agent (ESA) that is presently being developed for the correction of anemia in patients with chronic renal failure. Unlike currently marketed ESAs, Hematide does not possess any sequence homology to erythropoietin (EPO) and has not elicited moribund immune responses in animal safety studies thereby allowing the generation of a robust safety package. Animals administered marketed ESAs develop anti-EPO antibodies that null the effect of the administered ESA and neutralize endogenous EPO, resulting in severe anemia that precludes the interpretation of chronic safety studies. The primary objective of this study is to determine whether Hematide-specific antibodies are generated when male monkeys are exposed to high Hematide doses (10 mg/kg, intravenous [IV] and subcutaneous [SC]) administered at frequent dosing intervals (every two weeks) for a total of 9 doses; secondary objectives are to evaluate whether developed antibodies impact pharmacokinetics (PK) and pharmacology. In this study, no Hematide-specific antibodies were detected. Hematide exhibits a prolonged plasma half-life and slow clearance by either IV or SC administration. Hematide induced significant erythropoiesis with reticulocytosis and subsequent increases in red blood cells, hematocrit and hemoglobin (Hgb) levels. No erythropoietic differences were noted between the IV and the SC dosed groups with mean ± SD Hgb levels of 20.9 ± 2.5 and 20.3 ± 2.1 g/dL, respectively, occurring on Day 48, corresponding to Hgb increases of 6.5 and 6.7 g/dL, respectively, over pre-dose levels. In conclusion, Hematide is a potent erythropoiesis stimulating agent that exhibits plasma persistence in monkeys. Similar erythropoietic responses were produced following IV and SC administration. The absence of antibody development suggests that Hematide, at the doses and regimen described, has a low immunogenic potential in cynomolgus monkeys.