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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Research Article Oncology

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 1

Expression of agonistic TRAIL-Rs TRAIL-R1/DR4 and TRAIL-R2/DR5 on primary leukemia cells from newly diagnosed pediatric high-risk BPL patients.

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Expression of agonistic TRAIL-Rs TRAIL-R1/DR4 and TRAIL-R2/DR5 on primar...
Leukemia cells from diagnostic bone marrow specimens of 21 high-risk BPL patients were stained by direct immunofluorescence for BPL-associated surface antigens CD10, CD19, and CD34 as well as the death receptors DR4 and DR5. (A) FACS-correlated 2-color fluorescence dot plots of primary leukemia cells from 3 randomly selected representative BPL cases. (B) Cluster figure demonstrating the higher percentage of positivity of leukemia cells for the CD10, CD19, and CD34 antigens versus DR4 or DR5, when examined by direct immunofluorescence and flow cytometry. (C) Depicted are bar graphs comparing the percentage of positivity (mean ± SEM) for CD19 receptor versus DR4 and DR5 death receptors on primary leukemia cells from all 21 patients shown in B. Significant effect sizes were determined using paired t tests for each patient sample comparing CD19+ versus DR4+ or DR5+. *P < 0.0001 vs. DR4+, P < 0.0001 vs. DR5+. (D) Bivariate plots of DR4 versus DR5 exhibited a significant positive correlation in expression of these receptors on primary BPL cells (n = 21, t test on slope parameter, P = 0.0006). Bivariate plots of DR4 and DR5 with CD34 revealed that CD34 was significantly correlated with DR5 expression (n = 21, P =0.0095) and a trend existed toward a positive correlation with DR4 expression (n = 21, P = 0.096). (E) Depicted are bar graphs comparing the percentage of positivity (mean ± SEM) for DR4 (n = 21) and DR5 (n = 21) on primary leukemia cells from CD34+ versus CD34– BPL patients (t test) using a 30% positivity cut-off for the immunophenotypic classification.