Background and purpose: Anaemia of chronic disease (ACD) has been linked to iron-restricted erythropoiesis imposed by high circulating levels of hepcidin, a 25 amino acid hepatocyte-derived peptide that controls systemic iron homeostasis. Here, we report the engineering of the human lipocalin-derived, small protein-based anticalin PRS-080 hepcidin antagonist with high affinity and selectivity.
Experimental approach: Anticalin- and hepcidin-specific pharmacokinetic (PK)/pharmacodynamic modelling (PD) was used to design and select the suitable drug candidate based on t1/2 extension and duration of hepcidin suppression. The development of a novel free hepcidin assay enabled accurate analysis of bioactive hepcidin suppression and elucidation of the observed plasma iron levels after PRS-080-PEG30 administration in vivo.
Key results: PRS-080 had a hepcidin-binding affinity of 0.07 nM and, after coupling to 30 kD PEG (PRS-080-PEG30), a t1/2 of 43 h in cynomolgus monkeys. Dose-dependent iron mobilization and hepcidin suppression were observed after a single i.v. dose of PRS-080-PEG30 in cynomolgus monkeys. Importantly, in these animals, suppression of free hepcidin and subsequent plasma iron elevation were sustained during repeated s.c. dosing. After repeated dosing and followed by a treatment-free interval, all iron parameters returned to pre-dose values.
Conclusions and implications: In conclusion, we developed a dose-dependent and safe approach for the direct suppression of hepcidin, resulting in prolonged iron mobilization to alleviate iron-restricted erythropoiesis that can address the root cause of ACD. PRS-080-PEG30 is currently in early clinical development.
© 2018 The British Pharmacological Society.