Abstract B134: IMPDH1 and IMPDH2 as therapeutic targets in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) tumors are dependent on purine biosynthesis for proliferation and survival and relapsed ALL is particularly associated with transcriptional up-regulation of this pathway. Increased dependency on purine biosynthesis highlights IMPDH (inosine monophosphate dehydrogenase), the rate-limiting enzyme in guanosine production, as a potential therapeutic target for the treatment of ALL. To assess the role of IMPDH1 and IMPDH2 in ALL development and progression, we generated NOTCH1-induced leukemias from Impdh1 knockout and Impdh2 conditional knockout mice. In addition, we have completed whole exome sequencing and RNAseq profiling of 12 pairs of ALL xenografts corresponding to matched diagnostic and relapsed ALL samples and have performed dose response assays with the IMPDH inhibitor mizoribine. Additionally and towards the identification of synthetic lethal genetic vulnerabilities with IMPDH inhibition in ALL we have performed a genome wide CRISPR screen in REH ALL cells with the IMPDH inhibitor mizoribine. Overall, these studies highlight the therapeutic potential for IMPDH inhibitors for the treatment of ALL. Citation Format: Chelsea Dieck, Koichi Oshima, Alberto Ambesi-Impiombato, Adolfo Ferrando. IMPDH1 and IMPDH2 as therapeutic targets in acute lymphoblastic leukemia [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B134. doi:10.1158/1535-7163.TARG-19-B134