<i>In vitro</i> and <i>in vivo</i> induction of fetal hemoglobin with a reversible and selective DNMT1 inhibitor

Abstract

Pharmacological induction of fetal hemoglobin (HbF) expression is an effective therapeutic strategy for the management of β-hemoglobinopathies such as sickle cell disease. DNA methyltransferase (DNMT) inhibitors 5-azacytidine (5-aza) and 5-aza-2′-deoxycytidine (decitabine) have been shown to induce HbF expression in both preclinical models and clinical studies, but are not currently approved for the management of hemoglobinopathies. We report here the discovery of a novel class of orally bioavailable DNMT1-selective inhibitors as exemplified by GSK3482364. This molecule potently inhibits the methyltransferase activity of DNMT1, but not DNMT family members DNMT3A or DNMT3B. In contrast with cytidine analog DNMT inhibitors, the DNMT1 inhibitory mechanism of GSK3482364 does not require DNA incorporation and is reversible. In cultured human erythroid progenitor cells, GSK3482364 decreased overall DNA methylation resulting in derepression of the -globin genes HBG1 and HBG2 and increased HbF expression. In a transgenic mouse model of sickle cell disease, orally administered GSK3482364 caused significant increases in both HbF levels and in the percentage HbF-expressing erythrocytes, with good overall tolerability. We conclude that in these preclinical models, selective, reversible inhibition of DNMT1 is sufficient for the induction of HbF, and is well-tolerated. We anticipate that GSK3482364 will be a useful tool molecule for the further study of selective DNMT1 inhibition both in vitro and in vivo .

Clinical advances in targeting epigenetics for cancer therapy

“…Unlike nucleoside analogs that incorporate into DNA, these non-nucleoside analogs directly target the catalytic sites of specific DNMT enzymes [21]. For example, RG108, DC_517, and GSK3482364 have been discovered as reversible and selective non-nucleoside DNMT1 inhibitors, which exhibit potent inhibition of DNA methylation and antitumor activity [21][22][23]. Further preclinical and clinical studies are needed to evaluate whether they offer favorable outcomes over nucleoside analogs.…”

Sickle cell disease: progress towards combination drug therapy

“…75,76 These observations led to investigations of DNMT1 inhibitors including cytidine 5-azacytidine and its analogue 2 0 deoxy-5-azacytidine (decitabine) for HbF induction. [77][78][79][80][81] Decitabine incorporates into DNA 82 and is a potent DNMT1 inhibitor with a favourable safety profile. Parenteral decitabine has been shown to be effective in increasing HbF in patients with SCD, including those refractory to hydroxycarbamide therapy.…”

“…The development of DNMT inhibition, through gene silencing in human erythroid precursors, using chemicals or DNMT1 knockout in transgenic mice, results in reactivation of HBG transcription 75,76 . These observations led to investigations of DNMT1 inhibitors including cytidine 5‐azacytidine and its analogue 2′deoxy‐5‐azacytidine (decitabine) for HbF induction 77–81 . Decitabine incorporates into DNA 82 and is a potent DNMT1 inhibitor with a favourable safety profile.…”

Drug design targeting active posttranslational modification protein isoforms

“…Some of them have shown early treatment benefits in clinical studies, such as the first KRAS G12C irreversible inhibitor, AMG510, 246 in multiple solid tumors and MAK683 of EED targeting allosteric inhibitor of PRC complex. Most recently discovered inhibitors such as a potent reversible and allosteric DNMT1 inhibitor GSK3482364, 374 an irreversible H3K36 methyltransrase NSD1 inhibitor BT5, 375 and the irreversible RhoA inhibitor DC‐Rohin, 54 providing attractive chemical starting points to further investigate those novel mechanism driven compounds into more promising therapeutics as precision medicines.…”