Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia
Fatih M. Uckun, … , Osmond J. D’Cruz, Hong Ma
Fatih M. Uckun, … , Osmond J. D’Cruz, Hong Ma
Published January 26, 2015
Citation Information: J Clin Invest. 2015;125(3):1006-1018. https://doi.org/10.1172/JCI76610.
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Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia

Abstract

Patients with B cell precursor acute lymphoblastic leukemia (BPL) respond well to chemotherapy at initial diagnosis; however, therapeutic options are limited for individuals with BPL who relapse. Almost all BPL cells express CD19, and we recently cloned the gene encoding a natural ligand of the human CD19 receptor (CD19L). We hypothesized that fusion of CD19L to the soluble extracellular domain of proapoptotic TNF-related apoptosis-inducing ligand (sTRAIL) would markedly enhance the potency of sTRAIL and specifically induce BPL cell apoptosis due to membrane anchoring of sTRAIL and simultaneous activation of the CD19 and TRAIL receptor (TRAIL-R) apoptosis signaling pathways. Here, we demonstrate that recombinant human CD19L-sTRAIL was substantially more potent than sTRAIL and induced apoptosis in primary leukemia cells taken directly from BPL patients. CD19L-sTRAIL effectively targeted and eliminated in vivo clonogenic BPL xenograft cells, even at femtomolar-picomolar concentrations. In mice, CD19L-sTRAIL exhibited a more favorable pharmacokinetic (PK) profile than sTRAIL and was nontoxic at doses ranging from 32 fmol/kg to 3.2 pmol/kg. CD19L-sTRAIL showed potent in vivo antileukemic activity in NOD/SCID mouse xenograft models of relapsed and chemotherapy-resistant BPL at nontoxic fmol/kg dose levels. Together, these results suggest that recombinant human CD19L-sTRAIL has clinical potential as a biotherapeutic agent against BPL.

Authors

Fatih M. Uckun, Dorothea E. Myers, Sanjive Qazi, Zahide Ozer, Rebecca Rose, Osmond J. D’Cruz, Hong Ma

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Figure 3

Recombinant human CD19L-sTRAIL causes apoptosis in primary BPL cells and BPL xenograft cells at picomolar concentrations.

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Recombinant human CD19L-sTRAIL causes apoptosis in primary BPL cells and...
(A) BPL cells from xenograft clone no. 11 were treated for 48 hours at 37°C with CD19L-sTRAIL (2.1 pM), CD19L (25 nM), or sTRAIL (250 nM). Controls included untreated cells. Apoptosis is evidenced by the significantly lower percentages of annexin V–FITC–PI– live cells located in the left lower quadrant of the corresponding 2-color fluorescence dot plots. After CD19L-sTRAIL treatment, cells exhibited marked shrinkage, with altered side scatter (SSC) as well as decreasing numbers of remaining cells in the P1 lymphoid window in the corresponding forward scatter (FSC)/SSC light scatter plot from the 10,000 cells analyzed. (B and C) Primary leukemia cells from 31 newly diagnosed and 3 relapsed patients with BPL and 21 xenograft clones derived from 8 newly diagnosed and 3 relapsed pediatric BPL patients were subjected to CD19L-sTRAIL or 2 Gy γ-rays. Cells were analyzed for apoptosis as in A. Depicted are bar graphs showing the mean ± SEM values for the percentage of apoptotic leukemia cells for each treatment group; statistical significance was assessed utilizing planned linear contrasts versus 2 Gy γ-rays (mixed ANOVA model, with treatment dose as the fixed factor and cell type as a random factor).*P ≤ 0.0001 vs. 2 Gy; **P = 0.0002 vs. 2 Gy. Number of samples analyzed in B: 2 Gy γ-rays, n = 17; 21 fM, n = 2; 210 fM, n = 6; 2.1 pM, n = 32; 4.2 pM, n = 7; 10 pM, n = 6; 21 pM, n = 7. Number of samples analyzed in C: 2 Gy γ-rays, n = 18; 2.1 pM, n = 18; 21 pM, n = 3; 210 pM, n = 3.