EPZ011989

Despite evidence that EZH2 silencing in MDS/MPN can promote AML pathogenesis, our data demonstrate that the therapeutic inhibition of EZH2 in established AML has the potential to improve survival.

Treatment with IFNɣ or EPZ011989, an inhibitor of enhancer of zeste-homolog 2 (EZH2), resulted in greater HLA-I in K562 ASXL1c (85.0% vs 50.2% and 89.5% vs 39.3%, respectively, q<0.001) suggesting that ASXL1c acts orthogonally to IFNɣ or EZH2...Specifically, we link DLIr to ASXL1m that suppresses transcription of HLA-I and antigen presentation machinery in myeloid diseases; moreover, its correction restores anti-leukemic CD8+ T-cell cytotoxicity. Ongoing studies will examine additional clinical contexts and the epigenetic mechanisms by which ASXL1m regulates HLA-I expression.

Treatment with EPZ011989, an EZH2 inhibitor, derepressed SLFN11 expression in 361-PBDr and other SLFN11-deficient tumor cells, and increased sensitivity to PBD and PBD-conjugated ADCs, indicating that the suppression of SLFN11 expression is associated with histone methylation as reported. Moreover, we demonstrated that combining an ataxia telangiectasia and Rad3-related protein (ATR) inhibitor, AZD6738, with SG3199 or PBD-based ADCs led to synergistic cytotoxicity in either resistant 361-PBDr cells or cells that SLFN11 was knocked down via siRNA. Collectively, these data provide insights into potential development of resistance to PBDs and PBD-conjugated ADCs, and more importantly, inform strategy development to overcome such resistance.

The findings provide valuable experimental evidence for the targeted epigenetic therapy of AML. The present results demonstrate an epigenetic regulation-based superior antileukemic therapy.

Furthermore, in an ectopic engraft model of SCLC, disruption of EZH2/DNMT1 function using the combination treatment of EPZ011989 and Decitabine potently abrogated the inhibition of macrophage infiltration and thus suppressed tumor growth, the effect of which was impaired by CCL2 neutralization or macrophage depletion. Overall, this work provides new insights into the role of macrophages in SCLC and establishes a rationale for constructing novel therapeutic avenues for SCLC patients.

Here, we determined whether an inhibitor of EZH2 enhanced the effect of standard of care chemotherapeutic agents: irinotecan, vincristine, and cyclophosphamide. The Pediatric Preclinical Testing Program (PPTP) previously reported the activity of the EZH2 inhibitor tazemetostat (EPZ6438) against xenograft models of rhabdoid tumors. EPZ011989 significantly prolonged time to event in all the six rhabdoid models studied but did not induce tumor regression. The addition of EPZ011989 to standard of care agents significantly improved time to event in at least one model for each of the agents studied, although this effect was observed in only a minority of the combination testing experiments.