Contributions
Abstract: EP841
Type: E-Poster Presentation
Session title: Iron metabolism, deficiency and overload
Background
Hepcidin is known as the master regulator of systemic iron homeostasis with reduction in synthesis leading to the development of iron overload. Hepcidin gene expression is negatively modulated by matriptase-2 (MT-2), a liver-specific type II transmembrane serine protease. MT-2 cleaves hemojuvelin (HJV), leading to the extracellular release of soluble HJV (sHJV) fragments and suppression of hepcidin expression. Therefore, inhibition of MT-2 represents a potential therapeutic strategy for diseases caused by inappropriately low hepcidin leading to iron overload or where therapeutic iron restriction may be used to control excessive erythrocytosis. DISC-B is a potent (MT-2 Ki =15 nM) and selective small molecule MT-2 inhibitor.
Aims
- To examine the dose-dependency of acute treatment of DISC-B on the key PD markers (hepcidin-25, sHJV, serum iron) in cynomolgus monkeys.
- To determine the time to maximum decrease in serum iron upon multiple dosing.
- To evaluate the effect of chronic treatment on key hematologic parameters.
Methods
A cross-over study was conducted in male cynomolgus monkeys (2-4-year-old; N=6). Animals were administered a single subcutaneous (SC) dose of DISC-B at 5, 15, 50 mg/kg or vehicle control, followed by administration of DISC-B once a day for 7 consecutive days; the washout period in between treatments was 2 weeks. For the single-dose treatments, blood samples were collected 48-hr prior to treatment (baseline) and at various time points after dosing. For the multiple dose part of the study, blood samples were collected 48-hr prior to dosing (baseline) and at various time points after the 1st and the 7th dose. All blood samples were processed to serum and sHJV, hepcidin-25, serum iron and total iron binding capacity (TIBC) were quantified. In addition, for the multiple dose part of the study, reticulocyte hemoglobin was determined at baseline and on Day 7. TSAT was calculated as the ratio of serum iron/TIBC x 100.
Results
Treatment of DISC-B resulted in a dose-dependent increase in hepcidin-25 with a maximum of 5-fold. Maximum serum iron percent reduction from baseline was 10%, 25%, and 50% for 5, 15, and 50 mg/kg, respectively. The magnitude of hepcidin-25 modulation was similar at 15 and 50 mg/kg dose. However, the serum iron reduction was higher with the 50 mg/kg group and responses were more consistent across different animals. Therefore, we selected the 15 mg/kg dose group to determine if the effect on serum iron would increase with subsequent days of dosing. After 7 days of treatment with DISC-B at 15 mg/kg serum iron decreased from 25% on day 1 to 45% at day 7 (~2-fold). The hepcidin-25 increase over baseline was comparable on day 1 and day 7. Importantly, all animals showed a reduction in CHr with a mean reduction of 1.3 pg (± 0.6) on day 7 compared to their baseline levels, suggesting the induction of iron-restricted erythropoiesis.
Conclusion
DISC-B modulates serum hepcidin-25 levels and iron homeostasis in cynomolgus monkeys in a dose-dependent manner. The consistent increase in hepcidin-25 and the increasing reduction in serum iron after 7 doses of DISC-B suggest that prolonged inhibition of MT-2 can lead to sustained, therapeutically relevant reduction in serum iron. Our data demonstrate that MT-2 can be successfully inhibited by a selective small molecule to increase hepcidin and decrease serum iron.
Keyword(s): Hepcidin, Iron metabolism
Abstract: EP841
Type: E-Poster Presentation
Session title: Iron metabolism, deficiency and overload
Background
Hepcidin is known as the master regulator of systemic iron homeostasis with reduction in synthesis leading to the development of iron overload. Hepcidin gene expression is negatively modulated by matriptase-2 (MT-2), a liver-specific type II transmembrane serine protease. MT-2 cleaves hemojuvelin (HJV), leading to the extracellular release of soluble HJV (sHJV) fragments and suppression of hepcidin expression. Therefore, inhibition of MT-2 represents a potential therapeutic strategy for diseases caused by inappropriately low hepcidin leading to iron overload or where therapeutic iron restriction may be used to control excessive erythrocytosis. DISC-B is a potent (MT-2 Ki =15 nM) and selective small molecule MT-2 inhibitor.
Aims
- To examine the dose-dependency of acute treatment of DISC-B on the key PD markers (hepcidin-25, sHJV, serum iron) in cynomolgus monkeys.
- To determine the time to maximum decrease in serum iron upon multiple dosing.
- To evaluate the effect of chronic treatment on key hematologic parameters.
Methods
A cross-over study was conducted in male cynomolgus monkeys (2-4-year-old; N=6). Animals were administered a single subcutaneous (SC) dose of DISC-B at 5, 15, 50 mg/kg or vehicle control, followed by administration of DISC-B once a day for 7 consecutive days; the washout period in between treatments was 2 weeks. For the single-dose treatments, blood samples were collected 48-hr prior to treatment (baseline) and at various time points after dosing. For the multiple dose part of the study, blood samples were collected 48-hr prior to dosing (baseline) and at various time points after the 1st and the 7th dose. All blood samples were processed to serum and sHJV, hepcidin-25, serum iron and total iron binding capacity (TIBC) were quantified. In addition, for the multiple dose part of the study, reticulocyte hemoglobin was determined at baseline and on Day 7. TSAT was calculated as the ratio of serum iron/TIBC x 100.
Results
Treatment of DISC-B resulted in a dose-dependent increase in hepcidin-25 with a maximum of 5-fold. Maximum serum iron percent reduction from baseline was 10%, 25%, and 50% for 5, 15, and 50 mg/kg, respectively. The magnitude of hepcidin-25 modulation was similar at 15 and 50 mg/kg dose. However, the serum iron reduction was higher with the 50 mg/kg group and responses were more consistent across different animals. Therefore, we selected the 15 mg/kg dose group to determine if the effect on serum iron would increase with subsequent days of dosing. After 7 days of treatment with DISC-B at 15 mg/kg serum iron decreased from 25% on day 1 to 45% at day 7 (~2-fold). The hepcidin-25 increase over baseline was comparable on day 1 and day 7. Importantly, all animals showed a reduction in CHr with a mean reduction of 1.3 pg (± 0.6) on day 7 compared to their baseline levels, suggesting the induction of iron-restricted erythropoiesis.
Conclusion
DISC-B modulates serum hepcidin-25 levels and iron homeostasis in cynomolgus monkeys in a dose-dependent manner. The consistent increase in hepcidin-25 and the increasing reduction in serum iron after 7 doses of DISC-B suggest that prolonged inhibition of MT-2 can lead to sustained, therapeutically relevant reduction in serum iron. Our data demonstrate that MT-2 can be successfully inhibited by a selective small molecule to increase hepcidin and decrease serum iron.
Keyword(s): Hepcidin, Iron metabolism