Whole-genome CRISPR screening identifies N-glycosylation as an essential pathway and a potential novel therapeutic target in CALR-mutant MPN (Whole Genome CRISPR Screen).

Calreticulin (CALR) mutations are frequent, disease-initiating events in myeloproliferative neoplasms (MPN). Although the biological mechanism by which CALR mutations cause MPN has been elucidated, there currently are no clonally selective therapies for CALR-mutant MPN. To identify unique genetic dependencies in CALR-mutant MPN, we performed a whole-genome CRISPR knockout depletion screen in mutant CALR-transformed hematopoietic cells. We found that genes in the N-glycosylation pathway (amongst others) were differentially depleted in mutant CALR-transformed cells as compared with control cells. Using a focused pharmacological screen targeting unique vulnerabilities uncovered in the CRISPR screen, we found that chemical inhibition of N-glycosylation impaired the growth of mutant CALR-transformed cells in vitro. We treated Calr-mutant knockin mice with the N-glycosylation inhibitor, 2-deoxy-glucose (2-DG), and found a preferential sensitivity of Calr-mutant cells to 2-DG as compared to wild-type cells, and a normalization of key MPN disease features. These findings advance the development of clonally selective treatments for CALR-mutant MPN. Whole-genome CRISPR screen, n=2 biological replicates per cell line, BA/F3-MPL cells expressing an empty vector or CALR 52 bp deletion (DEL52), grown in the presence or absence of interleukin 3 (IL3).