UBTF tandem duplications and KMT2A/Menin complex co-occupy genomic targets dysregulated in UBTF-TD acute myeloid leukemias
UBTF-TD acute myeloid leukemias are sensitive to Menin inhibition
UBTF tandem duplications (UBTF-TDs) have recently emerged as a recurrent alteration in pediatric and adult acute myeloid leukemia (AML). UBTF-TD leukemias are characterized by a poor response to conventional chemotherapy and a transcriptional signature that mirrors NUP98-rearranged and NPM1-mutant AMLs, including HOX gene dysregulation. However, the mechanism of how UBTF-TD drives leukemogenesis remains unknown. In this study, we investigated the genomic occupancy of UBTF-TD in transformed cord-blood CD34+ (cbCD34+) cells and patient-derived xenograft models. We found that UBTF-TD protein maintained genomic occupancy at ribosomal DNA (rDNA) loci while also occupying genomic targets commonly dysregulated in UBTF-TD myeloid malignancies, such as the HOXA/HOXB gene clusters and MEIS1. These data suggest that UBTF-TD is a gain-of-function alteration that results in mislocalization to genomic loci dysregulated in UBTF-TD leukemias. UBTF-TD also co-occupies key genomic loci with KMT2A and Menin, which are known to be key partners involved in HOX-dysregulated leukemias. Using a protein degradation system, we showed that stemness, proliferation, and transcriptional signatures are dependent on sustained UBTF-TD localization to chromatin. Finally, we demonstrate that primary cells from UBTF-TD leukemias are sensitive to the Menin inhibitor SNDX-5613, resulting in markedly reduced in vitro and in vivo tumor growth, myeloid differentiation, and abrogation of the UBTF-TD leukemic expression signature. These findings provide a viable therapeutic strategy for patients with this high-risk AML subtype.