Enhanced induction of fetal hemoglobin by the combination of decitabine with RN-1 in β-thalassemia/HbE erythroid progenitor cells

Abstract

Background: Fetal hemoglobin (HbF; α<inf>2</inf>γ<inf>2</inf>) induction is a well-established approach for β-hemoglobinopathies, including sickle cell disease (SCD) and β-thalassemia. Decitabine, a DNA methyltransferase 1 (DNMT1) inhibitor, has been shown to effectively induce HbF production with a favorable safety profile. However, more potent therapeutic strategies are needed, particularly for β-thalassemia/HbE patients. Methods: We evaluated the HbF-inducing efficacy of ten DNMT1 inhibitors in erythroid progenitor cells derived from β-thalassemia/HbE patients. To further enhance HbF induction, we investigated a combination treatment with decitabine and RN-1, a lysine-specific demethylase 1 (LSD1) inhibitor. HbF expression, cell viability, erythroid differentiation, and proliferation were assessed. Additionally, we investigated the association between treatment response and well-characterized single-nucleotide polymorphisms (SNPs) previously linked to HbF expression. Results: Of the ten DNMT1 inhibitors tested, SGI-110, a dinucleotide analog of decitabine, exhibited similar HbF-inducing efficacy and toxicity profiles as decitabine at equivalent molar dose. The combination treatment with decitabine and RN-1 resulted in a robust additive increase in HbF expression in β-thalassemia/HbE erythroid progenitor cells, albeit with a slight reduction in cell viability. Additionally, the combination treatment improved the delayed differentiation phenotype in β-thalassemia/HbE erythroid cells, accompanied by a reduction in cell proliferation. Interestingly, individual variability in response to RN-1 and the combination treatments was observed, with major responders exhibiting significantly greater increases in HbF compared to minor responders. We identified two SNPs in the BCL11A gene (rs766432 and rs1427407) that were potentially associated with a higher likelihood of major response to treatments. Conclusions: Our findings highlight the potential of targeting two distinct epigenetic corepressors within the γ-globin repressor complex to achieve robust HbF induction. The combination of decitabine and RN-1 represents a promising therapeutic strategy for β-thalassemia, warranting further investigation into the molecular mechanisms underlying individual response variability.