Session: 113. Hemoglobinopathies, Excluding Thalassemia: Basic and Translational: Poster II
Hematology Disease Topics & Pathways:
Research, Sickle Cell Disease, Hemoglobinopathies, Diseases
CD34+ HSPCs from 3 donors were differentiated in vitro to erythroblasts with vehicle, 20 μM of FG-4592, or 50 μM of HU. Flow cytometric analysis on Day 9 showed that FG-4592 treatment increased % F-cells by 1.47-fold (±0.45), compared to a 2.21-fold (±0.89) increase with HU (Fig. 1). We then transplanted lethally irradiated (1000 rads) male 6–8-week-old C57BL/6J mice with bone marrow from transgenic sickle cell mice (Hb SS; Townes model, Jackson Laboratory). Twelve weeks after transplantation, mice with >80% engraftment of the donor HbSS phenotype, determined by Hb electrophoresis, were used for subsequent experiments. Vehicle, 25 mg/kg FG-4592, or 50 mg/kg FG-4592 was administered three times weekly through intraperitoneal injection for 8 weeks. All mice underwent retro-orbital bleeding at baseline (48 h pretreatment), 2, 4, 6, and 8 weeks of treatment for hematological evaluation, including Hb, hematocrit, and reticulocyte % (Fig. 1). At the end of 8 weeks, livers, kidneys, and plasma were collected. Hb and hematocrit levels increased in the 50 mg/kg FG-4592 group compared to the other groups at 4 weeks but decreased by 8 weeks for all groups. Reticulocyte % also decreased in all groups at the 4- and 8-week timepoints. Red cell distribution width (RDW) and platelet count up-trended while mean corpuscular volume (MCV) and mean corpuscular Hb (MCH) down-trended over the 8 weeks, suggestive of an evolving iron deficiency contributing to worsening anemia. Quantitative PCR detected a 182% increase in liver EPO transcript and a 68% increase in kidney EPO transcript in the 50 mg/kg FG-4592 treated group, compared to vehicle. No changes in liver hepcidin transcription were observed in any group. ELISA analysis detected increased plasma EPO and decreased plasma hepcidin levels with increasing doses of FG-4592. None of these trends, except increases in RDW, were statistically significant.
Our study is the first to characterize the effect of HIF-PHI drugs in a mouse model of SCD. Preliminary data confirm an effect of FG-4592 on HbF induction and suggest that FG-4592 may increase EPO expression and decrease hepcidin levels in SCD mice. These results highlight the potential of prolyl hydroxylase inhibition as a novel therapeutic approach for chronic anemia in SCD. Future directions include testing higher doses of FG-4592 to induce a stronger erythropoietic effect and monitoring additional markers of iron homeostasis in our mouse model of SCD.
Disclosures: Straub: Creegh Pharmaceuticals: Consultancy, Current equity holder in publicly-traded company. Xu: GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees.
OffLabel Disclosure: FG-4592 is an inhibitor of hypoxia inducible factor prolyl hydroxylase, recently approved internationally for treatment of anemia in chronic kidney disease. FG-4592 was purchased from Cayman Chemical.
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