USE OF USP7 INHIBITORS FOR THE TREATMENT OF ACUTE MYELOID LEUKEMIA (AML)

摘要

Resistance of acute myeloid leukemia (AML) cells to DNA damaging therapeutic agents is dependent on CHK1 protein levels. Here, the inventors demonstrate that in AML, CHK1 protein stability relies on the expression and activity of Ubiquitin Specific Protease 7 (USP7). CHK1 and USP7 levels are positively correlated in AML cell lines and primary patient specimens with high CHK1 protein levels. USP7 associates with CHK1, leading to its stabilization by deubiquitinylation, and this association is enhanced in response to cytarabine treatment. Pharmacological or RNA interference-mediated inhibition of USP7 significantly reduced AML proliferation in vitro and in vivo, and increased AML cell death. It is important to note that USP7 inhibition synergized with cytarabine to kill AML cell lines. This is also the case in primary patient specimens with high CHK1 levels. Transcriptomic dataset analyses revealed that a USP7 gene signature is highly enriched in cells from AML patients at relapse, as well as in residual blasts from Patient Derived Xenograft (PDX) models treated with clinically relevant doses of cytarabine, strongly suggesting a relationship between USP7 expression and resistance to therapy. Finally, single cell analysis from AML patient at relapse versus diagnosis showed that a gene signature of the pre-existing subpopulation responsible for relapse is enriched in transcriptomes of patients with high USP7 level. Altogether, these data demonstrate that USP7 is a master regulator of CHK1 protein kinase in AML cells, and represents both a marker of resistance to chemotherapeutic treatments, as well as a potential therapeutic target to overcome treatment resistance.