CBFA2T3-GLIS2 model of pediatric acute megakaryoblastic leukemia identifies FOLR1 as a CAR T cell target

Fusion oncoproteins are the initiating event in the pathogenesis of many pediatric AML. The CBFA2T3-GLIS2 (C/G) fusion is a product of a cryptic translocation primarily seen in infants and early childhood and is associated with dismal outcome. Here, we demonstrate that the expression of the C/G oncogenic fusion protein promotes the transformation of human cord blood hematopoietic stem/progenitor cells (CB HSPCs) in an endothelial cell (EC) co-culture system, that recapitulates the transcriptome, morphology and immunophenotype of C/G AML and induces highly aggressive leukemia in xenograft models. Interrogating the transcriptome of C/G-CB cells and primary C/G AML identified a library of C/G fusion-specific genes that are potential targets for therapy. We developed chimeric antigen receptor (CAR) T cells directed against one of the targets, FOLR1, and demonstrated their pre-clinical efficacy against C/G AML using in vitro and xenograft models. FOLR1 is also expressed in renal and pulmonary epithelium, raising concerns for toxicity that must be addressed for the clinical application of this therapy. Our findings underscore the role of the endothelial niche in promoting leukemic transformation of C/G-transduced CB HSPCs. Furthermore, this work has broad implications for studies of leukemogenesis applicable to a variety of oncogenic fusion-driven pediatric leukemias, providing a robust and tractable model system to characterize the molecular mechanisms of leukemogenesis and identify biomarkers for disease diagnosis and targets for therapy.

Changes in glutathione in intact erythrocytes during incubation with penicillamine as detected by 1H spin-echo NMR spectroscopy

1H spin-echo NMR spectroscopy was used to study changes in glutathione status in intact erythrocytes. The concentration of glutathione in suspensions of erythrocytes in 2H2O saline is significantly different in cells from patients with rheumatoid arthritis than in controls from normal healthy volunteers. It is observed that the methods of separation and suspension affect lactate metabolism in red cells. Incubation of erythrocytes with solutions of the therapeutic agent D-penicillamine in 2H2O saline produced a change in glutathione resonances which is indicative of an increase in diglutathione concentration. Signals from the methyl groups of penicillamine decreased at a commensurate rate. Incubation of normal cells with plasma from patients with rheumatoid arthritis who had the same blood group as the normal volunteer indicated a much larger fall in glutathione signal with plasma from a patient treated with penicillamine than from a patient on non-steroidal anti-inflammatories.