3 Week IV Study of RGMC Ab in Female Sprague Dawley Rats

High levels of hepcidin, the main regulator of systemic iron metabolism leads 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 (mAbs) ABT-207 and h5F9-AM8 which inhibit hemojuvelin also known as repulsive guidance molecule c (RGMc) and downregulate hepcidin. After a single application of these antibodies hepcidin expression in liver and its concentration in serum 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 ~80 fold higher than ABT-207. When hepcidin levels were downregulated iron deposition in the liver was visible histologically one week post application. The anitbody-mediated iron deposition was not associated with any toxicologically relevant effect at the doses and timepoints evaluate. Iron depositions seen after 14 weekly treatments with ABT-207 were partially 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.

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