EPZ5676

EPZ5676 is a potent inhibitor of DOT1L histone methyltransferase, according to X-ray crystallographic analysis, that occupies the S-adenosyl methionine (SAM) binding pocket of DOT1L and induces conformational changes in DOT1L resulting in the opening of a hydrophobic pocket beyond the amino acid portion of SAM. EPZ5676 selectively inhibits DOTIL with a value of 50% inhibition concentration IC₅₀ of 0.8 nM, which is 37000-fold greater in selectivity than other methyltransferases, including CARM1, EHMT1/2, EZH1/2, PRMT1/2/5/6/8, SETD7, SMYD2/3, and WHSC1/1L1. EPZ5676 has been investigated for the treatment of MLL-rearranged leukemia in multiple studies where results have shown that EPZ5676 inhibits H3K79 methylation and the expression of MLL-fusion target gene and potently kills acute leukemia cell lines bearing MLL translocation.

Reference

Daigle SR, Olhava EJ, Therkelsen CA, Basavapathruni A, Jin L, Boriack-Sjodin PA, Allain CJ, Klaus CR, Raimondi A, Scott MP, Waters NJ, Chesworth R, Moyer MP, Copeland RA, Richon VM, Pollock RM. Potent inhibition of DOT1L as treatment of MLL-fusion leukemia. Blood. 2013 Aug 8;122(6):1017-1025.

Tri-methylation of H3K79 is decreased in TGF-beta1-induced epithelial-to-mesenchymal transition in lung cancer.[Pubmed:28804523]

Clin Epigenetics. 2017 Aug 8;9:80.

BACKGROUND: The epithelial-to-mesenchymal transition (EMT) enables epithelial cancer cells to acquire mesenchymal features and contributes to metastasis and resistance to treatment. This process involves epigenetic reprogramming for gene expression. We explored global histone modifications during TGF-beta1-induced EMT in two non-small cell lung cancer (NSCLC) cell lines and tested different epigenetic treatment to modulate or partially reverse EMT. RESULTS: Loss of classical epithelial markers and gain of mesenchymal markers were verified in A549 and H358 cell lines during TGF-beta1-induced EMT. In addition, we noticed increased expression of the axonal guidance protein semaphorin 3C (SEMA3C) and PD-L1 (programmed death-ligand 1) involved in the inhibition of the immune system, suggesting that both SEMA3C and PD-L1 could be the new markers of TGF-beta1-induced EMT. H3K79me3 and H2BK120me1 were decreased in A549 and H358 cell lines after a 48-h TGF-beta1 treatment, as well as H2BK120ac in A549 cells. However, decreased H3K79me3 was not associated with expression of the histone methyltransferase DOT1L. Furthermore, H3K79me3 was decreased in tumors compared in normal tissues and not associated with cell proliferation. Associations of histone deacetylase inhibitor (SAHA) with DOT1L inhibitors (EPZ5676 or SGC0946) or BET bromodomain inhibitor (PFI-1) were efficient to partially reverse TGF-beta1 effects by decreasing expression of PD-L1, SEMA3C, and its receptor neuropilin-2 (NRP2) and by increasing epithelial markers such as E-cadherin. CONCLUSION: Histone methylation was modified during EMT, and combination of epigenetic compounds with conventional or targeted chemotherapy might contribute to reduce metastasis and to enhance clinical responses.

DOT1L as a therapeutic target for the treatment of DNMT3A-mutant acute myeloid leukemia.[Pubmed:27335278]

Blood. 2016 Aug 18;128(7):971-81.

Mutations in DNA methyltransferase 3A (DNMT3A) are common in acute myeloid leukemia and portend a poor prognosis; thus, new therapeutic strategies are needed. The likely mechanism by which DNMT3A loss contributes to leukemogenesis is altered DNA methylation and the attendant gene expression changes; however, our current understanding is incomplete. We observed that murine hematopoietic stem cells (HSCs) in which Dnmt3a had been conditionally deleted markedly overexpress the histone 3 lysine 79 (H3K79) methyltransferase, Dot1l. We demonstrate that Dnmt3a(-/-) HSCs have increased H3K79 methylation relative to wild-type (WT) HSCs, with the greatest increases noted at DNA methylation canyons, which are regions highly enriched for genes dysregulated in leukemia and prone to DNA methylation loss with Dnmt3a deletion. These findings led us to explore DOT1L as a therapeutic target for the treatment of DNMT3A-mutant AML. We show that pharmacologic inhibition of DOT1L resulted in decreased expression of oncogenic canyon-associated genes and led to dose- and time-dependent inhibition of proliferation, induction of apoptosis, cell-cycle arrest, and terminal differentiation in DNMT3A-mutant cell lines in vitro. We show in vivo efficacy of the DOT1L inhibitor EPZ5676 in a nude rat xenograft model of DNMT3A-mutant AML. DOT1L inhibition was also effective against primary patient DNMT3A-mutant AML samples, reducing colony-forming capacity (CFC) and inducing terminal differentiation in vitro. These studies suggest that DOT1L may play a critical role in DNMT3A-mutant leukemia. With pharmacologic inhibitors of DOT1L already in clinical trials, DOT1L could be an immediately actionable therapeutic target for the treatment of this poor prognosis disease.