Rational design of an immunoconjugate for selective knock-down of leukemia-specific E2A-PBX1 fusion gene expression in human Pre-B leukemia.

Abstract

The t(1;19)(q23;p13) is one of the most common chromosomal translocations in acute lymphoblastic leukemia (ALL) and results in production of the transforming oncoprotein E2A-PBX1. Here we first report a novel, biomarker-guided biotherapy strategy for personalized treatment of t(1;19)(+) ALL. A supervised interrogation of the gene expression profiles of primary leukemic cells from a cohort of 207 children with high risk B-lineage ALL identified up-regulated CD19 gene expression as a biomarker for t(1;19)(+) ALL. A disulfide-linked immunoconjugate of a 5-amino-modified 24 mer phosphorothioate anti-sense E2A-PBX1 oligonucleotide (AON) with a mAb specific for a CD19 receptor (αCD19-AON) was prepared as a CD19-directed and leukemia-specific biotherapeutic agent against E2A-PBX1(+) B-lineage ALL. Treatment of E2A-PBX1(+) leukemia cells with low nanomolar concentrations of αCD19-AON resulted in selective depletion of E2A-PBX1 transcripts and caused apoptotic destruction and abrogation of clonogenic growth. Subcutaneously administered αCD19-AON at a total dose level of 93 nmol kg(-1) delivered over 14 days using a micro-osmotic pump more than doubled the leukemia-free survival time of SCID mice in a xenograft model of E2A-PBX1(+) human B-lineage ALL (82.0 ± 1.9 days vs. 37.0 ± 0.1 days, P < 0.0001). Both the AON moiety and the targeting CD19-specific mAb moiety were required for the in vitro as well as in vivo anti-leukemic activity of αCD19-AON. The observed in vitro and in vivo anti-leukemic potency of the αCD19-AON immunoconjugate provides the first preclinical proof-of-principle that t(1;19)(+) high risk B-lineage ALL can be treated with leukemia-specific biotherapeutic agents that knock-down E2A-PBX1 expression.

• Authors: Fatih M Uckun, Sanjive Qazi, Ilker Dibirdik, Dorothea E Myers
• Journal: Integrative biology : quantitative biosciences from nano to macro (Integr Biol (Camb)) Vol. 5 Issue 1 Pg. 122-32 (Jan 2013) ISSN: 1757-9708 [Electronic] England
• PMID: 22990208 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Basic Helix-Loop-Helix Transcription Factors
• DNA-Binding Proteins
• Immunoconjugates
• Pre-B-Cell Leukemia Transcription Factor 1
• Proto-Oncogene Proteins
• Recombinant Fusion Proteins
• TCF3 protein, human
• pbx1 protein, human

Topics

• Animals
• Basic Helix-Loop-Helix Transcription Factors (genetics, immunology)
• Child
• DNA-Binding Proteins (genetics, immunology)
• Drug Design
• Gene Knockdown Techniques (methods)
• Humans
• Immunoconjugates (therapeutic use)
• Mice
• Mice, SCID
• Pre-B-Cell Leukemia Transcription Factor 1
• Precursor Cell Lymphoblastic Leukemia-Lymphoma (drug therapy, immunology)
• Precursor Cells, B-Lymphoid (immunology)
• Proto-Oncogene Proteins (genetics, immunology)
• Recombinant Fusion Proteins (immunology)
• Treatment Outcome
• Tumor Cells, Cultured
• Xenograft Model Antitumor Assays