Single-Cell Analyses Reveal Megakaryocyte-Biased Hematopoiesis in Myelofibrosis and Identify Mutant Clone-Specific Targets

Myelofibrosis is a severe myeloproliferative neoplasm characterised by increased numbers of abnormal bone marrow megakaryocytes that induce fibrosis, destroying the hematopoietic microenvironment. To determine the cellular and molecular basis for aberrant megakaryopoiesis in myelofibrosis, we performed single-cell transcriptome profiling of 135,929 CD34+Lineage- hematopoietic stem/progenitor cells (HSPCs), single-cell proteomics, genomics and functional assays. We identified a bias towards megakaryocyte differentiation apparent from early multipotent stem cells in myelofibrosis and associated aberrant molecular signatures. A sub-fraction of myelofibrosis megakaryocyte progenitors (MkP) were transcriptionally similar to healthy-donor MkP but the majority were disease-specific, with distinct populations expressing fibrosis- and proliferation-associated genes. Mutant-clone HSPCs showed increased expression of megakaryocyte-associated genes compared to wild-type HSPCs, and we provide early validation of G6B as a potential immunotherapy target. Our study paves the way for selective targeting of the myelofibrosis clone and illustrates the power of single-cell multi-omics to discover tumor-specific therapeutic targets and mediators of tissue fibrosis. Overall design: We used 10x genomics platform to profile single-cell transcriptome of CD34+Lineage- hematopoietic stem/progenitor cells (HSPCs) derived from 16 human myelofibrosis tissue samples and 5 healthy donors