Anti-repulsive Guidance Molecule C (RGMc) Antibodies Increases Serum Iron in Rats and Cynomolgus Monkeys by Hepcidin Downregulation

High levels of hepcidin, the main regulator of systemic iron metabolism, lead to various diseases. Targeting hepcidin and lowering its concentration is a possible form of intervention in order to treat these diseases. High turnover rate of hepcidin is a major drawback of therapies directly targeting this peptide. We developed two monoclonal antibodies ABT-207 and h5F9-AM8 which inhibit hemojuvelin/repulsive guidance molecule C (RGMc) and downregulate hepcidin. We conducted single-application and dose response studies to understand the antibodies’ mechanism and subchronic toxicology studies to exclude safety-related concerns. Investigation was carried out at different biological levels through qPCR, Affymetrix, liquid chromatography coupled with mass spectrometry (LC-MS/MS), histopathology, serum iron, unsaturated iron binding capacity (UIBC), and drug concentration measurements. After a single application of these antibodies, hepcidin expression in liver and its serum protein levels were reduced. Serum iron increased for several weeks. The RGMc antibodies show a pronounced dose response relationship in rats with h5F9-AM8 having an IC₅₀ (UIBC) of approximately 80-fold higher than ABT-207. When hepcidin levels were downregulated, iron deposition in the liver was visible histologically 1 week post application. These antibody-mediated iron depositions were not associated with any adverse toxicologically relevant effect at the doses and time points evaluated. Iron depositions seen after 14 weekly treatments with ABT-207 were reversible in rats and in cynomolgus monkeys. Due to their long-lasting effects and excellent safety profile, both RGMc-blocking antibodies ABT-207 and h5F9-AM8 are favorable clinical candidates for diseases characterized by high serum hepcidin levels like anemia of chronic disease.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9770-4) contains supplementary material, which is available to authorized users.KEY WORDS: ABT-207, h5F9-AM8, hepcidin, PK/PD analysis, safety assessment     

Evaluation of safety and efficacy outcomes of direct oral anticoagulants versus warfarin in normal and extreme body weights for the treatment of atrial fibrillation or venous thromboembolism

Journal of Thrombosis and Thrombolysis - Despite evolving evidence, the use of direct oral anticoagulants (DOACs) in patients with extremes of body weight remains controversial. This study aimed to...     

Early postoperative complications following liver transplantation

Liver transplantation is a highly successful treatment for patients with end-stage liver disease and acute liver failure. However, serious postoperative complications can significantly compromise patient survival. Complications can be technical, medical, or immunological in nature. The risk of developing early postoperative complications is associated with the patient's preoperative condition, the quality of the donor liver, the quality of the donor and recipient procedure, initial graft function, and perioperative anaesthesiological and intensive care management. The patient's preoperative condition can include gastrointestinal bleeding, acute renal failure, a requirement for cathecholamines or mechanical ventilation, and prolonged encephalopathy for the most detrimental risk factors for developing early postoperative complications. The necessity for prolonged mechanical ventilation or the requirement for reintubation after transplantation can significantly increase the risk of developing pneumonia, sepsis, and multiple organ dysfunction. A decrease in infectious and other complications can be achieved by early postoperative enteral nutition, including the application of probiotics.