KRAS G12D Blocks Erythroid Differentiation and Promotes Inflammatory Pathways at the Single Cell Level in Myeloid Malignancies 2251571

Abstract Introduction Myeloid neoplasms (MN) are characterized by myeloid blast expansion that blocks hematopoietic differentiation and causes cytopenia, a major cause of morbidity and mortality. KRASG12D mutations occur in up to 15% of MN, are enriched in therapy-resistant disease, and are linked to poor prognosis. Currently, no precision medicine strategies exist for KRASG12D-mutant MN. Progress has been limited by the lack of representative models and difficulty distinguishing KRAS-mutant from wildtype cells in patient samples. Methods To address this, we used Genotyping of Transcriptomes (GoT), which co-captures single cell RNA-seq and mutational status within the same thousands of individual cells to elucidate specific KRASG12D-driven pathways in preleukemic Clonal Hematopoiesis (CH) and 3 Acute Myeloid Leukemia (AML) patient samples. We also developed a novel transplantable AdenoCreLox KRASG12D mouse model. Results In AML, mutant cells formed a distinct inflammatory, stem/progenitor-like population with elevated CD83 expression and quiescent features. In vitro, KRASG12D CD83+ cells displayed higher stemness and reduced differentiation compared to CD83− cells. An isolated KRASG12D CH sample revealed mutant cell overrepresentation in the myeloid lineages, specifically monocytes and erythrocytes. Treatment with a KRASG12D-specific inhibitor (MRTX1133) restored wildtype erythroid differentiation and downregulated inflammatory genes, including CD83. Lastly, a KRASG12D mouse model mimicking human disease with extramedullary granulocytic tumors was developed, where CD83 marked mutant cells. Resolution of these phenotypes was achieved with MRTX1133 treatment. Conclusion Therefore, KRASG12D drives erythroid differentiation block, monocytic bias, and inflammation, which MRTX1133 reverses. We identify a novel quiescent CD83+ KRASG12D progenitor population in AML and demonstrate the therapeutic potential of MRTX1133 in vivo. Additionally, targeting CD83+ quiescent cells may prevent AML progression in KRASG12D patients. Funding Source n/a Topic Categories Immune Mechanisms of Human Disease (HUM)