A diphtheria toxin-interleukin 3 fusion protein is cytotoxic to primitive acute myeloid leukemia progenitors but spares normal progenitors

• Published in: Cancer research (Chicago, Ill.) Vol. 62; no. 6; pp. 1730 - 1736
• Main Authors: FEURING-BUSKE, Michaela, FRANKEL, Arthur E, ALEXANDER, Richard L, GERHARD, Brigitte, HOGGE, Donna E
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.03.2002
• Subjects: Acute Disease; Adult; Aged; Animals; Antineoplastic agents; Antineoplastic Agents - pharmacology; Antineoplastic Agents - toxicity; Biological and medical sciences; Diphtheria Toxin - pharmacology; Diphtheria Toxin - toxicity; Female; Humans; Immunotherapy; In Situ Hybridization, Fluorescence; Interleukin-3 - pharmacology; Interleukin-3 - toxicity; Leukemia, Monocytic, Acute - drug therapy; Leukemia, Monocytic, Acute - pathology; Leukemia, Myeloid - drug therapy; Leukemia, Myeloid - pathology; Leukemia, Myeloid, Acute - drug therapy; Leukemia, Myeloid, Acute - pathology; Leukemia, Myelomonocytic, Acute - drug therapy; Leukemia, Myelomonocytic, Acute - pathology; Male; Medical sciences; Mice; Mice, Inbred NOD; Mice, SCID; Middle Aged; Myeloid Progenitor Cells - drug effects; Neoplastic Stem Cells - drug effects; Pharmacology. Drug treatments; Recombinant Fusion Proteins - pharmacology; Recombinant Fusion Proteins - toxicity; Xenograft Model Antitumor Assays; Antineoplastic agent; Human; Cell culture; Cytotoxicity test; Acute; Stem cell; Cytokine; Hematopoietic cell; Tissue specificity; Malignant hemopathy; Diphtheria; In vitro; Biological activity; Infection; Toxin; Interleukin 3; Cell death; Bacteriosis; Fusion protein; Progenitor cell; Acute myelocytic leukemia
• ISSN: 0008-5472; 1538-7445

The relative cytotoxicity of a diphtheria toxin (DT) human interleukin 3(IL3) fusion protein (DT(388)IL3) was tested against primitive normal (n = 3)and acute myeloid leukemia (AML) progenitors (n = 7). After 24-h culture with 50 ng/ml DT(388)IL3, the mean percentages of kill of AML colony-forming cells (CFCs), long-term culture-initiating cells (LTC-ICs), and suspension culture-ICs (SC-ICs) were 82% (range, 47-100), 56% (range, 28-91), and 74% (range, 43-87), respectively, with most surviving progenitors being cytogenetically normal. Engraftment of DT(388)IL-3-treated AML cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice followed for 16 weeks was eradicated for two of these samples. In contrast, with normal bone marrow, mean percentages of CFC kill of 49 and 64% were seen with 50 or 250 ng/ml DT(388)IL3, respectively, whereas no significant kills were observed in the LTC-IC and SC-IC assays. The NOD/SCID mouse repopulating cell (RC) frequency in normal BM cells was also not reduced by DT(388)IL3 treatment. In subsequent experiments, NOD/SCID mice that received AML blasts i.v. followed in 24 h by 0.045 microg/g DT(388)IL3 daily i.p. x 5 showed mean percentages of reduction in AML engraftment of 83% (range, 14-100) and 57% (range, 0-98) after 4 and 12 weeks, respectively (n = 6). No evidence of leukemia was detected with two of six AML samples 12 weeks after one 5-day course of DT(388)IL3. Repeating the DT(388)IL3 treatment every 4 weeks enhanced its effectiveness against two additional samples. Thus, DT(388)IL3 kills primitive leukemic progenitors from a proportion of AML patients but shows no significant toxicity against equivalent normal cells.