Background: Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL) in the US accounting for about 22% of newly diagnosed cases of B-cell NHL. It is considered to be more aggressive and to have worse prognosis due to low response to existing treatments. KDM4 is a family of histone demethylases that can drive tumor growth by regulating transcription, cell cycle, and DNA replication/repair. Overexpression of KDM4 alters post-translational histone modification and is associated with many types of cancer, including DLBCL. TACH101 is a novel, potent small molecule inhibitor of KDM4 that is being developed for treatment of advanced cancers, including DLBCL.

Methods: TACH101 was evaluated in vitro and in vivo using cancer cell lines and patient-derived organoid (PDO) and xenograft (PDX) models of DLBCL.

Results: TACH101 is a reversible, α-ketoglutarate competitive, selective and potent inhibitor of KDM4 isoforms A-D with IC50 values < 0.100 μM for all four isoforms. An initial screen using a 301-cell line panel showed that DLBCL cell lines are sensitive to TACH101 (IC50 < 10 nM). In an additional panel of DLBCL cell lines, TACH101 inhibited proliferation in a dose-dependent manner in all DLBCL cell lines, independent of molecular subtype, with mean IC50’s of 0.03 ± 0.01 μM in ABC DLBCL cell lines (n=6); 0.02 ± 0.01 μM in GCB DLBCL cell lines (n=7) and 0.02 ± 0.01 μM in PMBL DLBCL cell lines (n=2). In OCI-LY19 DLBCL xenografts in vivo, TACH101 was well tolerated and inhibited tumor growth by 55% to 100%, depending on dosing regimen (either QD or BID following a 3 days on/4 days off schedule). In PK studies, TACH101 exhibited low clearance, moderate volume of distribution, and good oral bioavailability in mouse, rat, and dog. Moreover, treatment with TACH101 resulted in little or no inhibitory effects on CYP enzymes. Toxicity studies in rats and dogs identified potential target tissues and provided safety guidance for the use of TACH101 in human studies.

Conclusions: The KDM4 inhibitor, TACH101, had compelling activity in preclinical DLBCL models, suggesting that TACH101 could be an effective therapy for DLBCL. Preparations to advance the drug into clinical trials are underway.

Citation Format: Frank Perabo, Chandtip Chandhasin, Sanghee Yoo, Joselyn Del Rosario, Young K. Chen, Ellen Filvaroff, Jeffrey A. Stafford, Stephen Quake, Michael F. Clarke. TACH101, a first-in-class inhibitor of KDM4 histone lysine demethylase for the treatment of diffuse large B-cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3720.