The FAD-directed LSD1 specific inhibitor, INCB059872, is a promising epigenetic agent for AML therapy by inducing differentiation of leukemic stem/ progenitor cells

Numerous studies have elucidated that the most pivotal functions of lysine specific demethylase-1 (LSD1) are associated with regulating normal or malignant hematopoiesis by maintaining stem cell self-renewal and regulating myeloid differentiation. In preclinical models, studies with either pharmacological inhibition or genetic knockdown of LSD1 demonstrated that LSD1 is essential for differentiation of progenitor cells during normal hematopoiesis. In the clinic, AML manifests itself via clonal expansion of abnormal differentiation and proliferation of myeloid cells and, therefore, the inhibition of LSD1 activity with small molecule inhibitors could be a promising therapeutic approach for AML. Previously, we reported upon the identification of a flavin adenine dinucleotide (FAD) directed LSD1 specific inhibitor, INCB059872, which is efficacious in preclinical mouse models utilizing human AML cell lines and primary AML cells by inducing cell differentiation as indicated by the induction of CD11b and CD86 markers. Using a larger panel of myeloid and HSC flow cytometry markers, our currents efforts expanded upon these observations to ascertain whether INCB059872 enhanced lineage commitment at hematopoietic stem cell (HSC) and/ or promoted monocytic/granulocytic differentiation of human primary AML cells ex vivo and in human systemic AML PDX models. In both human AML PDX models and human primary AML samples, INCB059872 increased myeloid differentiation with increasing populations of monocytes (CD14+) and granulocytes (CD15+). Furthermore, INCB059872 induced the differentiation of early hematopoietic progenitors, CD34+/CD38- to more committed CD34+/CD38+ multipotent/oligopotent progenitors, which in turn gave rise to lineage specific progenitors in the human AML PDX models. These studies support further exploration of INCB059872 as a promising novel epigenetic agent for AML therapy whose mechanism of action lies in part through the induction of differentiation of leukemic stem/progenitor cells to more committed hematopoietic lineages. Citation Format: Antony Chadderton, Min Ye, Melody Diamond, Valerie Roman, Michael Weber, Chunhong He, Liangxing Wu, Swamy Yeleswaram, Alan Roberts, Wenqing Yao, Gregory Hollis, Reid Huber, Peggy Scherle, Bruce Ruggeri, Sang Hyun Lee. The FAD-directed LSD1 specific inhibitor, INCB059872, is a promising epigenetic agent for AML therapy by inducing differentiation of leukemic stem/progenitor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1888.