Session: 113. Sickle Cell Disease, Sickle Cell Trait, and Other Hemoglobinopathies, Excluding Thalassemias: Basic and Translational: Poster I
Hematology Disease Topics & Pathways:
Research, Fundamental Science, Translational Research, Genetic Disorders, Diseases
Methods. We treated β-Yac mice (n=12) with oral AN-233 (300 and 400 mg/kg), 5 days/week for 4 weeks. Tail vein blood evaluated complete blood counts with differential (CBC), and flow cytometry quantified F-cells and mean fluorescence intensity (MFI). Next, we treated fragile SCD mice (n=12) with oral 300 mg/kg AN-233 alone or combined with HU (100 mg/kg), 5 days/week for 6 weeks. Body weights and blood collected at weeks 0, 3, and 6 weeks determined the effects of AN-233 on the CBC, γ-globin transcription, and F-cells and HbF levels. Spleens harvested at 6 weeks were used for H & E stain. Using a triple-quadrupole mass spectrometer, coupled with separation of compounds by reverse phase HPLC, plasma AN-233, and butyrate levels were measured. Finally, we treated three anemic baboons with AN-233 (300 mg/kg; 5 doses) subcutaneously and quantified CBC, F-cells, and HbF levels on various days post-treatment.
Results. Initial treatment of β-YAC mice with both doses of oral AN-233 was well tolerated and there were no deaths; the CBC remained stable without signs of toxicity. We observed a concentration-dependent increase in F-cells 2.6-fold (p=0.01) and 3.6-fold (p=2.0 E-07) for the 300 mg/kg and 400 mg/kg doses respectively, compared to a 2.9-fold increase for HU (p=0.0005). Since low dose AN-233 induced HbF without toxicity, we evaluated AN-233 (300 mg/kg) alone or combined with HU in fragile SCD mice. After 6 weeks of treatment, no adverse effects occurred on weights and CBC; one mouse died in each group including water supporting equal survival. Levels of γ-globin increased 2.5-fold (p=0.004), 1.6-fold (p=0.003), and 4.0-fold (p=0.006) respectively for AN-233, HU, and combination treatments; βS-globin mRNA levels did not change significantly. Parallel enhancement of F-cells 10.1-fold (p=0.001), 12.5-fold (p=0.01), and 13.8-fold (p=0.0005) for AN-233, HU, and combination therapy was produced. Significantly, higher MFI levels verified increased HbF protein per cell for all treatment groups and combination treatment produced a mild additive effect. Spleen analysis revealed a significant decrease in weights for the three treatments compared to control. For the water group, the H & E stain showed increased loss of lymphoid tissue, hemorrhagic infarcts, and ischemia. By contrast, AN-233 and HU restored lymphoid elements with enhanced hemosiderin-laden macrophages and megakaryocytes indicative of regeneration and extra-medullary hematopoiesis. By mass spectrometry, plasma AN-233 levels decreased by 3 h with a steady rise in butyrate from 3-9 h supporting drug activation in vivo. Lastly, three anemic baboons treated with AN-233 subcutaneously confirmed increases in F-cells from 31.2% (baseline) to 47.9% (p<0.025) and HbF protein levels increased 1.7-fold (p<0.015). Of note, redness and swelling occurred at the injection site for AN-233 treatments.
Conclusion. Our findings in SCD mice confirmed absorption and metabolism of oral AN-233, which produced sufficient rises in plasma butyrate to activate γ-globin transcription and HbF expression without adverse toxic effects. Moreover, baboon studies confirmed the ability of AN-233 to increase F-cells and HbF levels. This report supports developing AN-233 as a treatment option for individuals with SCD.
Disclosures: No relevant conflicts of interest to declare.
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