Anti-leukemic effect of TGN-1062, a novel CDK7 inhibitor, on AML-leukemic stem cells by targeting RNA modification and Mitochondrial metabolism

High expression of CDK7, a cell cycle regulator and transcriptional modulator, correlates with poor outcomes in acute myeloid leukemia (AML). We report that TGN-1062, a novel CDK7 inhibitor, exhibits significant antileukemic effects by inhibiting cell growth and inducing apoptosis in AML cell lines and primary CD34+CD38- blasts (enriched for leukemia stem cells; LSCs), while sparing normal CD34+CD38- cells (enriched for hematopoietic stem cells; HSCs). Our study revealed that TGN-1062 treatment in primary CD34+CD38- AML blasts suppress RNA m6A modification by downregulating METTL3/14 proteins, key components of the m6A methyltransferase complex that regulate RNA stability and translation. Decrease in METTL proteins reduced BCL-2 m6A RNA modification and led to increased BCL-2 mRNA decay and protein levels. BCL-2 downregulation resulted in disruption of mitochondrial metabolism and mitofusion in LSCs through decrease of HMGB1/HSPB1 and NRF2/DRP1 signaling, respectively. In vivo, TGN-1062 significantly reduced leukemia burden and prolonged survival in a murine MllPTD/WT/Flt3ITD/ITD AML model and in FLT3-WT and inv(16) AML patient-derived xenografts (PDXs). Increased survival in secondary transplant experiments supported TGN-1062 activity on LSCs. Of note, we proved that TGN-1062 synergized with the BCL-2 inhibitor, venetoclax in eliminating LSCs in both murine and PDX AML models, underscoring its potential as a promising therapeutic approach for AML patients.