Wenbin Xiao

Oncogenic RAS pathway mutations are associated with therapeutic resistance in acute myeloid leukemia, and identification of therapeutic vulnerabilities has been hindered by a lack of clinically relevant models and tractable ex vivo platforms. We utilize a bone marrow endothelial cell co-culture system to perform CRISPR screens on wild-type hematopoietic cells and isogenic leukemias with and without mutant Nras. We credentialed Elovl1, a very long chain fatty acid elongase, as a dependency in RAS pathway mutant leukemia using genetic and pharmacologic approaches. Metabolic and genetic studies in primary leukemias revealed that the fitness defect from Elovl1 loss reflects a mutant-specific dependency on de novo sphingolipid biosynthesis, specifically sphingomyelin production, as Sgms1 deletion phenocopies Elovl1 loss. Sphingomyelin-mediated generation of lipid rafts, key scaffolds for multiple signaling pathways, is essential to the survival of Nras-mutant AML cells. Our work leverages a new leukemia model to identify a targetable dependency in this treatment-refractory leukemia.

Chromatin and transcriptional changes mediated by KDM3B

Supplementary Table S4 from CRISPR Dependency Screens in Primary Hematopoietic Stem Cells Identify KDM3B as a Genotype-specific Vulnerability in IDH2- and TET2-mutant Cells

The 5th Edition of the World Health Organization Classification of Haematolymphoid Neoplasms (WHO5th) and the 2022 International Consensus Classification (ICC) both recognize myelodysplasia-related acute myeloid leukemia (AML-MR) as a diagnostic entity increasingly defined by integrated genomic data. Although largely concordant, the two classifications differ in various ways that should be resolved to achieve future harmonization. To address the areas of uncertainty, we retrospectively analyzed 615 newly diagnosed AML cases from adult patients treated at two large cancer centers. We demonstrate that AML-MR, whether defined by gene mutations (MR-GM) or cytogenetic abnormalities (MR-CGA), constitutes a prognostically distinct group with inferior outcome compared to most AML subtypes, second only to TP53-mutated or EVI1-rearranged AML. Isolated RUNX1 mutations were not associated with antecedent myeloid neoplasia. Neither the number of mutated MR genes nor their variant allele frequency independently impacted outcomes. Trisomy 8 and del(20q) did not confer inferior outcomes and may warrant exclusion from MR-CGA. Complex karyotype without TP53 mutations did not worsen outcomes within AML-MR and may be considered equivalent to other MR-CGA. The adverse prognosis of AML-MR appeared to be at least partly driven by ASXL1 and/or EZH2 mutations. These findings provide evidence toward a unified schema across the WHO5th and ICC.

Development of CRISPR screens with BMEC/HSPC co-cultures

Supplementary Table S5 from CRISPR Dependency Screens in Primary Hematopoietic Stem Cells Identify KDM3B as a Genotype-specific Vulnerability in IDH2- and TET2-mutant Cells

In vivo validation of Jmjd1c dependency