CBFA2T3-GLIS2 model of pediatric acute megakaryoblastic leukemia identifies FOLR1 as a CAR T cell target
Quy Le, … , Keith R. Loeb, Soheil Meshinchi
Quy Le, … , Keith R. Loeb, Soheil Meshinchi
Published September 22, 2022
Citation Information: J Clin Invest. 2022;132(22):e157101. https://doi.org/10.1172/JCI157101.
View: Text | PDF | Corrigendum
Research Article Oncology

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

Abstract

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 and progenitor cells (CB HSPCs) in an endothelial cell coculture system that recapitulates the transcriptome, morphology, and immunophenotype of C/G acute myeloid leukemia (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, folate receptor α (FOLR1), and demonstrated their preclinical 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.

Authors

Quy Le, Brandon Hadland, Jenny L. Smith, Amanda Leonti, Benjamin J. Huang, Rhonda Ries, Tiffany A. Hylkema, Sommer Castro, Thao T. Tang, Cyd N. McKay, LaKeisha Perkins, Laura Pardo, Jay Sarthy, Amy K. Beckman, Robin Williams, Rhonda Idemmili, Scott Furlan, Takashi Ishida, Lindsey Call, Shivani Srivastava, Anisha M. Loeb, Filippo Milano, Suzan Imren, Shelli M. Morris, Fiona Pakiam, Jim M. Olson, Michael R. Loken, Lisa Brodersen, Stanley R. Riddell, Katherine Tarlock, Irwin D. Bernstein, Keith R. Loeb, Soheil Meshinchi

×

Figure 7

In vitro and in vivo assessment of FOLR1 CAR T cells against primary AML cells derived from a C/G-positive patient.

Options: View larger image (or click on image) Download as PowerPoint
In vitro and in vivo assessment of FOLR1 CAR T cells against primary AML...
(A) Expression of FOLR1 in primary AML cells from C/G-positive patient B (see Figure 1 for details on this patient). Blue = stained with PE-labeled anti-FOLR1; gray = isotype control. (B) Cytolytic activity of CD8+ T cells unmodified or transduced with FOLR1 CAR following 6 hours of coculture with patient B AML cells. Data presented are mean leukemia-specific lysis ± SD from 3 technical replicates at indicated effector/target (E:T) ratios. Shown is representative experiment out of 3 experiments (see Supplemental Figure 14 for results from 2 additional donors). (C) Concentration of secreted IFN-γ and TNF-α in the supernatant following 24 hours of T cell/AML coculture at a 1:1 E:T ratio as measured by ELISA. Data are presented as mean ± SD from 3 technical replicates. Where concentrations of cytokines were too low to discern, the number above the x axis indicates the average concentration. Statistical significance was determined by unpaired, 2-tailed Student’s t test. **P < 0.005, ***P < 0.0005. Shown is representative experiment out of 2 experiments. (D) Schematic of experiment evaluating in vivo efficacy of FOLR1 CAR T cells against primary AML cells from patient B. Only 1 experiment was performed due to limited sample. (E) Bone marrow, liver, and spleen were harvested from control mice at necropsy following development of leukemia (60 days after T cell injection) as well as from 3 FOLR1 CAR T cell–treated mice selected at random 120 days after T cell injection. Percentage AML cells (defined as CD45dimCD56+) in the bone marrow, liver, and spleen are shown. n = 3 mice per group. Error bars denote ± SEM. Statistical significance was determined by unpaired, 2-tailed Student’s t test, assuming unequal variances. *P < 0.05, **P < 0.005. (F) Expression of FOLR1 among AML cells in the bone marrow, liver, and spleen from mice treated with unmodified T cells at necropsy. n = 3 mice per group. Error bars denote ± SEM. (G) Kaplan-Meier survival curves of PDX mice treated with unmodified or FOLR1 CAR T cells. Statistical differences in survival were evaluated using Mantel-Cox log-rank test. Only 1 experiment was performed for in vivo assessment. n = 3 mice per group.