Combination Targeted Therapy to Disrupt Aberrant Oncogenic Signaling and Reverse Epigenetic Dysfunction in <i>IDH2</i> - and <i>TET2</i> -Mutant Acute Myeloid Leukemia

Abstract

Genomic studies in acute myeloid leukemias (AML) have identified mutations that drive altered DNA methylation, including <i>TET2</i> and <i>IDH2</i> Here, we show that models of AML resulting from <i>TET2</i> or <i>IDH2</i> mutations combined with <i>FLT3</i>^ITD mutations are sensitive to 5-azacytidine or to the IDH2 inhibitor AG-221, respectively. 5-azacytidine and AG-221 treatment induced an attenuation of aberrant DNA methylation and transcriptional output and resulted in a reduction in leukemic blasts consistent with antileukemic activity. These therapeutic benefits were associated with restoration of leukemic cell differentiation, and the normalization of hematopoiesis was derived from mutant cells. By contrast, combining AG-221 or 5-azacytidine with FLT3 inhibition resulted in a reduction in mutant allele burden, progressive recovery of normal hematopoiesis from non-mutant stem-progenitor cells, and reversal of dysregulated DNA methylation and transcriptional output. Together, our studies suggest combined targeting of signaling and epigenetic pathways can increase therapeutic response in AML.<b>Significance:</b> AMLs with mutations in <i>TET2</i> or <i>IDH2</i> are sensitive to epigenetic therapy through inhibition of DNA methyltransferase activity by 5-azacytidine or inhibition of mutant IDH2 through AG-221. These inhibitors induce a differentiation response and can be used to inform mechanism-based combination therapy. <i>Cancer Discov; 7(5); 494-505. ©2017 AACR.</i><i>See related commentary by Thomas and Majeti, p. 459</i><i>See related article by Yen et al., p. 478</i><i>This article is highlighted in the In This Issue feature, p. 443</i>.