Investigating High-Risk Epigenetic Modifying Alterations on JAK2VF Dependency and Fibrotic Progression in Myeloproliferative Neoplasms (MPNs) - PROJECT SUMMARY/ABSTRACT Myeloproliferative Neoplasms (MPNs) are chronic, progressive hematopoietic disorders characterized by aberrant proliferation of myeloid lineage constituents, pro-inflammatory sequelae, progressive bone marrow fibrosis, and increased risk of leukemic transformation. Gain-of-function mutations of the JAK/STAT pathway, including JAK2VF, are present in the majority of MPN patients and are amenable to targeted inhibition; however, clinically-improved JAK2 inhibitors fail to reduce mutant allele burden, and response wanes over time. Somatic alterations in high-risk chromatin modifiers ASXL1 and EZH2 co-occur frequently with JAK2VF in MPN and confer adverse prognosis, myelofibrotic progression, and reduced response to JAK2 therapy. The mechanisms by which chromatin dysregulation secondary to ASXL1/EZH2 alterations enhance clonal evolution and pro-fibrotic inflammatory pathways to promote fibrosis progression and JAK2 inhibitor resistance have not been elucidated. Recently, we demonstrate an absolute requirement for mutant Jak2VF in MPN maintenance using a dual- recombinase knock-in/knock-out mouse model of Jak2VF. I hypothesize that Jak2VF cooperates with Asxl1 or Ezh2 loss to alter dependency on JAK/STAT signaling for disease maintenance and promote pro-inflammatory signaling pathways favoring fibrotic progression. In this proposal, I will investigate the requirement for oncogenic Jak2VF signaling and reversibility of epigenetic dysregulation and pro-inflammatory mediated fibrosis/niche remodeling in high-risk dual-mutant MPN using my dual-recombinase Jak2VF allele. I will complement this with single-cell DNA sequencing + immunophenotyping/cytokine analysis of clinical MPN specimens evaluating cytokine production, clonal evolution, and order of mutation acquisition in MF progression. Further understanding of the cooperative effects of chromatin dysregulation in fibrotic progression and therapeutic resistance in MPNs might lead to the identification of therapeutically tractable dependencies for this high-risk MPN patient subset. Andrew Dunbar, MD, an Assistant Attending at MSKCC, will conduct this project as part of a 5-year career development plan, dedicating >75% of his time to research with remainder on clinical work. Dr. Dunbar is mentored by Dr. Ross Levine, a world expert in the study of hematologic malignancies. Dr. Dunbar is advised by Drs. Raajit Rampal, Omar Abdel-Wahab, Richard Koche and Andriy Derkach at MSKCC, Dr. P. Brent Ferrell at Vanderbilt University Medical Center, and Dr. Rebekka Schneider at University Hospital RWTH Aachen, Germany. Andrew’s training will include gaining technical skills in performing and analyzing single-cell genotypic assays with formal courses in bioinformatics, modeling the bone marrow microenvironment, and methods to investigate the epigenetic regulation of hematopoietic stem cells. In the short term, the project goal is to publish two papers on the findings from this research. In the long term, the goal is for developing a research program and obtaining R01 funding to become an independent laboratory investigator in hematologic malignancies.
