Sensitization of B-cell chronic lymphocytic leukemia cells to recombinant immunotoxin by immunostimulatory phosphorothioate oligodeoxynucleotides.

Abstract

A recombinant anti-CD25 immunotoxin, LMB-2, has shown clinical efficacy in hairy cell leukemia and T-cell neoplasms. Its activity in B-cell chronic lymphocytic leukemia (B-CLL) is inferior but might be improved if B-CLL cells expressed higher numbers of CD25 binding sites. It was recently reported that DSP30, a phosphorothioate CpG-oligodeoxynucleotide (CpG-ODN) induces immunogenicity of B-CLL cells by up-regulation of CD25 and other antigens. The present study investigated the antitumor activity of LMB-2 in the presence of DSP30. To this end, B-CLL cells from peripheral blood of patients were isolated immunomagnetically to more than 98% purity. Incubation with DSP30 for 48 hours augmented CD25 expression in 14 of 15 B-CLL samples, as assessed by flow cytometry. DSP30 increased LMB-2 cytotoxicity dose dependently whereas a control ODN with no CpG motif did not. LMB-2 displayed no antitumor cell activity in the absence of CpG-ODN as determined colorimetrically with an (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. In contrast, B-CLL growth was inhibited in 12 of 13 samples with 50% inhibition concentrations (IC(50)) in the range of LMB-2 plasma levels achieved in clinical studies. Two samples were not evaluable because of spontaneous B-CLL cell death in the presence of DSP30. Control experiments with an immunotoxin that does not recognize hematopoietic cells, and an anti-CD22 immunotoxin, confirmed that sensitization to LMB-2 was specifically due to up-regulation of CD25. LMB-2 was much less toxic to normal B and T lymphocytes compared with B-CLL cells. In summary, immunostimulatory CpG-ODNs efficiently sensitize B-CLL cells to a recombinant immunotoxin by modulation of its target. This new treatment strategy deserves further attention.

• Authors: Thomas Decker, Susanne Hipp, Robert J Kreitman, Ira Pastan, Christian Peschel, Thomas Licht
• Journal: Blood (Blood) Vol. 99 Issue 4 Pg. 1320-6 (Feb 15 2002) ISSN: 0006-4971 [Print] United States
• PMID: 11830482 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adjuvants, Immunologic
• Antibodies, Monoclonal
• Antineoplastic Agents
• B3(Fv)-PE38KDEL recombinant immunotoxin
• CPG-oligonucleotide
• Exotoxins
• Immunotoxins
• Oligodeoxyribonucleotides
• Receptors, Interleukin-2
• Recombinant Proteins
• Thionucleotides

Topics

• Adjuvants, Immunologic (pharmacology, therapeutic use)
• Adult
• Aged
• Aged, 80 and over
• Antibodies, Monoclonal
• Antineoplastic Agents (pharmacology, therapeutic use)
• Drug Synergism
• Drug Therapy, Combination
• Exotoxins
• Female
• Humans
• Immunotoxins (pharmacology, therapeutic use)
• Leukemia, Lymphocytic, Chronic, B-Cell (drug therapy, pathology)
• Male
• Middle Aged
• Oligodeoxyribonucleotides (pharmacology, therapeutic use)
• Receptors, Interleukin-2 (biosynthesis, drug effects, immunology)
• Recombinant Proteins (pharmacology, therapeutic use)
• Thionucleotides (pharmacology, therapeutic use)
• Tumor Cells, Cultured (drug effects)
• Up-Regulation (drug effects)