The schedule for the Alberta Epigenetics Network Summit, which goes from March 21-23, is now available. Zenith has two abstracts that they will be presenting as poster presentations. One is on ZEN003694 and the other is on the discovery and characterization of covalent BET bromodomain inhibitors. I'm not sure what day these Zenith abstracts are being presented; either March 22 or 23. Also, Norman Wong is presenting on behalf of Resverlogix on RVX-208/Apabetalone and the BETonMACE Phase 3 Trial on the morning on March 22.

41. Discovery and Characterization of Covalent BET Bromodomain Inhibitors

Olesya A. Kharenko, Reena G. Patel, David Brown, Peter R. Young, Ravi Jahagirdar, Eric Campeau, Sarah Attwell, Emily M. Gesner, Karen Norek, Cyrus Calosing, Laura Tsujikawa, Sanjay Lakhotia, Henrik C. Hansen

Zenith Epigenetics Corp, Calgary AB Canada

BET bromodomain proteins are epigenetic readers which interact with the acetylated lysine (AcLys) residues of histones and transcription factors. Recently it has been shown that disruption of this interaction with small molecule BET bromodomain inhibitors is a promising approach to treat various disease states including cancer, inflammation, autoimmune and cardiovascular diseases.

Covalent inhibitors and covalent drugs offer several advantages including increased duration of action, more durable target modulation, and potential pharmacological effect at lower concentrations. To demonstrate that covalent inhibition is a promising approach to target BET proteins, we rationally designed and developed a series of covalent BET inhibitors. Using biochemical AlphaScreen assay we demonstrate that covalent BET inhibitors potently and selectively disrupt the interaction of BET bromodomains with AcLys histone peptides. Additionally, we show that the covalent interaction with BET bromodomains is time-dependent and can be monitored by thermodenaturation assay as a distinct peak from the non-covalent inhibitors. The covalent bond formation with BRD4 was further confirmed by high resolution crystal structure and MALDI spectrometry. In cellular assays, the covalent inhibitors potently inhibit proliferation and induce apoptosis in cancer cell lines. Importantly, the covalent inhibition of the BET proteins exhibits a sustained pharmacodynamic effect in washout experiments as demonstrated by enhanced inhibition of proliferation, decreased mRNA expression of several BET-dependent genes compared to reversible BET bromodomain inhibitors.

In summary, the first generation of the covalent inhibitors demonstrated promising durable target modulation which further prompted the development of a second generation of covalent inhibitors with good drug-like properties for future oncology applications.

42. Development of BET bromodomain inhibitor ZEN-3694 for the treatment of solid tumor and hematological malignancies and synergy with Standard of Care (SOC) therapies

Sarah Attwell, Eric Campeau, Ravi Jahagirdar, Olesya Kharenko, Karen Norek, Laura Tsujikawa, Cyrus Calosing, Reena Patel, Emily Gesner, Sanjay Lakhotia, Henrik Hansen

Zenith Epigenetics Corp, Calgary AB Canada

Targeting the interaction between bromodomain and extra-terminal domain (BET) proteins and acetyl-lysine on chromatin and transcription factors is a new therapeutic approach in clinical trials for cancer treatment. The BET proteins are involved in several transcriptional programs that drive cancer proliferation and metastasis. By using a combination of molecular modeling, structure activity relationship studies, biophysical and biomolecular assays, we developed a robust platform to assay different chemical scaffolds for inhibitory potency against BET bromodomains. Potent compounds were screened in cellular assays and in vivo models to further support preclinical development. Our clinical candidate ZEN-3694 binds selectively, suppresses oncogene expression, and inhibits proliferation in several models of hematological malignancies and solid tumors.

In vitro, ZEN-3694 has strong inhibitory activity with submicromolar IC50 values in several cell lines including castration-resistant prostate cancer (CRPC) and triple negative breast cancer (TNBC). ZEN-3694 also demonstrated synergy in vitro with Standard of Care (SOC) therapies in a wide variety of malignancies including Breast, Prostate, Lung, Melanoma, AML, and DLBCL. In vivo, xenograft studies in AML, CRPC and TNBC cancer models have shown ZEN-3694 to be well-tolerated and efficacious in a dose-dependent manner by inhibiting tumor growth.

Additionally, ZEN-3694 targets mechanisms of enzalutamide resistance in CRPC including constitutively active androgen receptor splice variant AR-V7 and induction of glucocorticoid receptor expression. ZEN-3694 is scheduled to enter phase I clinical studies in metastatic CRPC in Q1 2016.

08. Apabetalone (RVX-208) the first selective bromodomain extra-terminal (BET) protein inhibitor in clinical development for treatment of cardiovascular disease (CVD).

Norman CW Wong, Ewelina Kulikowski, Jan Johansson, Mike Sweeney,

Resverlogix Corporation Calgary, AB, Canada,

Apabetalone (RVX-208) is an orally active small molecule that was discovered in Alberta. It is the first BET inhibitor to enter into human trials for treating CVD. RVX-208 selectively inhibits the second binding domain of BET proteins from complexing with its natural ligand acetylated lysine marks on the tail of histones. In so doing, RVX-208 modulates gene transcription and has effects on pathways known to play important roles in CVD risks including the complement, coagulation, inflammation, and metabolism as well as increasing levels of the apolipoprotein A-I (apoAI), the major protein in high density lipoprotein(HDL). In addition to preclinical studies in vitro and in vivo, RVX-208 has been tested in many human trials lasting up to 6 months that in total enrolled almost 1000 patients.

In post-hoc analysis of the most recent studies, patients with CVD receiving 200 mg/day of RVX-208 had a 55% relative risk reduction in major adverse cardiac events (MACE) compared to placebo. The multiple actions of apabetalone arising from our in vitro and in human trials are based on targeted inhibition of BET proteins.

We believe activity RVX-208’s activity in vitro and in vivo may underpin its ability to lower MACE by beneficially affecting several important pathways known to contribute CVD risks in addition to raising apoA-I/HDL. Apabetalone is currently in a phase 3 clinical trial.