Allele-specific transcription of fetal genes in primary erythroid cell cultures from Lepore and δβ° thalassemia patients

Efficacy of Ruxolitinib as Inducer of Fetal Hemoglobin in Primary Erythroid Cultures from Sickle Cell and Beta-Thalassemia Patients

High levels of HbF may ameliorate the clinical course of β-thalassaemia and SCD. Hydroxyurea (HU) is the only HbF inducer approved for the treatment of patients. However not all patients respond to the treatment, for this reason it is noteworthy to identify new HbF inducers. Ruxolitinib is a JAK inhibitor that decreases the phosphorilation of STAT proteins. In particular STAT3 is a repressor of gamma-globin gene. The decrease of STAT3 phosphorilation could derepress gamma-globin gene and reactivate its trascription. In this study we evaluated the efficacy of ruxolitinib as inducer of HbF production. The analyses were performed in cultured erythroid progenitors from 16 beta-thalassemia intermedia (TI) and 4 sickle cell disease (SCD) patients. The use of quantitative RT-PCR technique allowed us to determine the increase of gamma-globin mRNA expression in human erythroid cultured cells treated with ruxolitinib. The results of our study demonstrated an increase in vitro of gamma-globin mRNA expression in almost all patients. These data suggest that ruxolitinib could be a good candidate to be used in vivo for the treatment of hemoglobinopathies.

Study on Hydroxyurea Response in Hemoglobinopathies Patients Using Genetic Markers and Liquid Erythroid Cultures

Increased expression of fetal hemoglobin (HbF) may ameliorate the clinical course of hemoglobinopathies. Hydroxyurea (HU) is the only inducer approved for the treatment of these diseases able to stimulate HbF production but patients' response is highly variable indicating the utility of the identification of pharmacogenomic biomarkers in order to predict pharmacological treatment efficacy. To date few studies to evaluate the role of genetic determinants in HU response have been conducted showing contradictory results. In this study we analyzed BCL11A, GATA-1, KLF-1 genes and γ-globin promoter in 60 alleles from 30 hemoglobinopathies patients under HU treatment to assess the role of these markers in HU response. We did not find any association between these genetic determinants and HU response. Before treatment started, the same patients were analyzed in vitro using liquid erythroid cultures in a test able to predict their response to HU. The results of our analysis confirm the absence of pharmacogenomic biomarker associated to HU response indicating that, the quantification of γ-globin mRNA fold increase remains the only method able to predict in vivo patients response to the drug.

Efficacy of Rapamycin as Inducer of Hb F in Primary Erythroid Cultures from Sickle Cell Disease and β-Thalassemia Patients

Phenotypic improvement of hemoglobinopathies such as sickle cell disease and β-thalassemia (β-thal) has been shown in patients with high levels of Hb F. Among the drugs proposed to increase Hb F production, hydroxyurea (HU) is currently the only one proven to improve the clinical course of these diseases. However, Hb F increase and patient's response are highly variable, indicating that new pharmacological agents could be useful for patients not responding to HU or showing a reduction of response during long-term therapy. In this study we evaluated the efficacy of rapamycin, a lypophilic macrolide used for the prevention of acute rejection in renal transplant recipients, as an inducer of Hb F production. The analyses were performed in cultured erythroid progenitors from 25 sickle cell disease and 25 β-thal intermedia (β-TI) patients. The use of a quantitative Real-Time-polymerase chain reaction ReTi-PCR technique and high performance liquid chromatography (HPLC) allowed us to determine the increase in γ-globin mRNA expression and Hb F production in human erythroid cells treated with rapamycin. The results of our study demonstrated an increase in vitro of γ-globin mRNA expression in 15 sickle cell disease and 14 β-TI patients and a corresponding Hb F increase. The induction by rapamycin, even if lower or similar in most of samples analyzed, in some cases was higher than HU. These data suggest that rapamycin could be a good candidate to be used in vivo for the treatment of hemoglobinopathies.

Quantification of HBG mRNA in primary erythroid cultures: prediction of the response to hydroxyurea in sickle cell and beta-thalassemia

BACKGROUND AND OBJECTIVE

Increased expression of fetal hemoglobin (HbF) may ameliorate the clinical course of hemoglobinopathies like sickle cell disease (SCD) and β-thalassemia. Hydroxyurea (HU) can stimulate HbF production in these diseases but the response is highly variable indicating the utility of developing an in vitro test to predict the patient's response to HU. We assessed whether the HbF response of patients with SCD and thalassemia intermedia (TI) to HU correlates with HBG (both γ-globin genes) expression in their cultured erythroid progenitors following exposure to HU.

PATIENTS AND METHODS

We exposed primary erythroid cultures from peripheral blood mononuclear cells from 30 patients with SCD and 15 with TI to HU and measured HBG mRNA by real-time quantitative PCR. The same patients were then treated with HU and their HbF response after treatment with a stable dose of HU was compared with the mRNA results in cultured cells.

RESULTS AND CONCLUSION

The fold increase in HBG mRNA in erythroid progenitors was similar to the fold increase in HbF in vivo. Quantification of HBG mRNA in erythroid progenitor cell cultures from patients with SCD and TI is predictive of their clinical response to HU.