Description:
Technology: Researchers at MUSC have identified several potential inhibitors of lysine-specific demethylase 1 (LSD1) utilizing a virtual screen and found compounds that fit the LSD1 active site in silico. Next, they synthesized these molecules and evaluated them as highly selective LSD1 inhibitors. The series of compounds are new chemical entities being evaluated as antitumor agents, or as compounds that possess low toxicity which can induce fetal hemoglobin to treat sickle cell. Several compounds inhibit LSD1 with Ki values in the mid-to upper nanomolar range. The most effective is compound 6 which at 500 nM promotes a 12.6-fold increase in the γ-globin gene of fetal hemoglobin in the K562 cell line, 6x greater than the current therapy, hydroxyurea (HU). (Figure 1.) This activity is retained in CD34+ erythrocyte precursor cells (5.4-fold increase).
Figure 1. Fold increase in mRNA for gamma globin from RT-qPCR.
Panel A: Fold increase in gamma globin mRNA expression in human CD34+ erythroid progenitor cells.
Panel C: Fold increase in gamma globin mRNA expression in the K562 human myelogenous leukemia cell line.
NS, not significant; **P < 0.0015; ***P < 0.0005; ****P < 0.0001.
The LSD1-containing DRED epigenetic complex is responsible for the silencing of the γ-globin gene and hence fetal hemoglobin production at 6 months of age. These new LSD1 inhibitors can be used to disrupt DRED and increase the cellular fetal hemoglobin content in vitro and in vivo. An in vivo study shows that compound 8 promoted an 87% increase in the γ-globin gene two weeks after treatment. (Figure 2.) These preliminary results suggest that the new LSD1 inhibitors will be better tolerated than the previously reported unsuccessful tranylcypromine-based LSD1 inhibitors, and could lead to an innovative and effective treatment for sickle cell disease.
Figure 2. Panel A: Two-week increase in the percentage of F-cells for compounds 4 and 8 at 10 mg/kg. Each data point is the average of three animals + SEM.
Panel B: HPLC trace showing that, relative to baseline or pretreatment (black line), compound 8 promoted an 87% increase in γ-globin in the Townes mouse model following 2 weeks of treatment.
Overview: Sickle cell disease (SCD) is the most common inherited blood disorder in the US. Affected patients are at risk of multi-system complications, significant morbidity and early mortality. Persons with SCD that possess increased % of fetal hemoglobin (HbF) have a less pain and fewer episodes of acute chest syndrome along with a decreased risk of mortality, since it is excluded from the from the sickle hemoglobin polymer. The only current FDA approved fetal hemoglobin inducer, Hydroxyurea, remains highly underutilized due (in part) to the risk of complications. The discovery of a new fetal hemoglobin stimulator could potentially revolutionize the care of affected patients. Epigenetic modification is one possible mechanism. Recent studies with the lysine specific demethylase (LSD-1) inhibitors, including tranylcypromine (TCP) show promising results. Unfortunately, TCP also has effects on monoamine oxidase and thus significant unwanted side effects. Developing a molecule with high specificity for LSD-1, low cross reactivity and negligible toxicity would increase effect and reduce unwanted side effects.
Applications: Therapeutic agents for various cancers as well as diabetes, cardiovascular diseases, neurological disorders, and sickle cell disease.
Advantages: Increased specificity for LSD1, which could reduce off-target effects, and improved pharmacokinetic parameters. Also, these compounds are reversible, non-covalent inhibitors that do not depend on bioactivation, as do tranylcypromine-based inhibitors currently in clinical trials.
Key Words: Sickle cell disease, hemoglobin, cancer, epigenetics, LSD1, tumor suppressor genes, DNA, histones, enzyme inhibitors.
Publication: Holshouser, Steven, et al. “Epigenetic Reexpression of Hemoglobin F Using Reversible LSD1 Inhibitors: Potential Therapies for Sickle Cell Disease” ACS Omega (2020); Kutz, Craig J., et al. "3, 5-Diamino-1, 2, 4-triazoles as a novel scaffold for potent, reversible LSD1 (KDM1A) inhibitors." MedChemComm (2014).
Inventors: Patrick Woster & Craig Kutz
Patent Status: US Patent 10,118,903
MUSC-FRD Technology ID: P1412a