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Oh S, Stish BJ, Sachdev D, Chen H, Dudek AZ, Vallera DA. A novel reduced immunogenicity bispecific targeted toxin simultaneously recognizing human epidermal growth factor and interleukin-4 receptors in a mouse model of metastatic breast carcinoma. Clin Cancer Res 2009; 15:6137-47. [PMID: 19789305 DOI: 10.1158/1078-0432.ccr-09-0696] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To develop a targeted biological drug that when systemically injected can penetrate to metastatic breast cancer tumors, one needs a drug of high potency and reduced immunogenicity. Thus, we bioengineered a novel bispecific ligand-directed toxin (BLT) targeted by dual high-affinity cytokines with a PE(38)KDEL COOH terminus. Our purpose was to reduce toxin immunogenicity using mutagenesis, measure the ability of mutated drug to elicit B-cell antitoxin antibody responses, and show that mutated drug was effective against systemic breast cancer in vivo. EXPERIMENTAL DESIGN A new BLT was created in which both human epidermal growth factor (EGF) and interleukin 4 cytokines were cloned onto the same single-chain molecule with truncated Pseudomonas exotoxin (PE(38)). Site-specific mutagenesis was used to mutate amino acids in seven key epitopic toxin regions that dictate B-cell generation of neutralizing antitoxin antibodies. Bioassays were used to determine whether mutation reduced potency, and ELISA studies were done to determine whether antitoxin antibodies were reduced. Finally, a genetically altered luciferase xenograft model was used; this model could be imaged in real time to determine the effect on the systemic malignant human breast cancer MDA-MB-231. RESULTS EGF4KDEL 7mut was significantly effective against established systemic human breast cancer and prevented metastatic spread. Mutagenesis reduced immunogenicity by approximately 90% with no apparent loss in in vitro or in vivo activity. CONCLUSIONS Because EGF4KDEL 7mut was highly effective even when we waited 26 days to begin therapy and because immunogenicity was significantly reduced, we can now give multiple drug treatments for chemotherapy-refractory breast cancer in clinical trials.
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Oh S, Ohlfest JR, Todhunter DA, Vallera VD, Hall WA, Chen H, Vallera DA. Intracranial elimination of human glioblastoma brain tumors in nude rats using the bispecific ligand-directed toxin, DTEGF13 and convection enhanced delivery. J Neurooncol 2009; 95:331-342. [PMID: 19517064 DOI: 10.1007/s11060-009-9932-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
Abstract
A bispecific ligand-directed toxin (BLT) consisting of human interleukin-13, epithelial growth factor, and the first 389 amino acids of diphtheria toxin was assembled in order to target human glioblastoma. In vitro, DTEGF13 selectively killed the human glioblastoma cell line U87-luc as well as other human glioblastomas. DTEGF13 fulfilled the requirement of a successful BLT by having greater activity than either of its monospecific counterparts or their mixture proving it necessary to have both ligands on the same single chain molecule. Aggressive brain tumors established intracranially (IC) in nude rats with U87 glioma genetically marked with a firefly luciferase reporter gene were treated with two injections of DTEGF13 using convection enhanced delivery resulting in tumor eradication in 50% of the rats which survived with tumor free status at least 110 days post tumor inoculation. An irrelevant BLT control did not protect establishing specificity. The bispecific DTEGF13 MTD dose was measured at 2 microg/injection or 0.5 microg/kg and toxicity studies indicated safety in this dose. Combination of monospecific DTEGF and DTIL13 did not inhibit tumor growth. ELISA assay indicated that anti-DT antibodies were not generated in normal immunocompetent rats given identical intracranial DTEGF13 therapy. Thus, DTEGF13 is safe and efficacious as an alternative drug for glioblastoma therapy and warrants further study.
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Vallera DA, Chen H, Sicheneder AR, Panoskaltsis-Mortari A, Taras EP. Genetic alteration of a bispecific ligand-directed toxin targeting human CD19 and CD22 receptors resulting in improved efficacy against systemic B cell malignancy. Leuk Res 2009; 33:1233-42. [PMID: 19327829 DOI: 10.1016/j.leukres.2009.02.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/03/2009] [Accepted: 02/05/2009] [Indexed: 12/28/2022]
Abstract
A bispecific ligand-directed toxin (BLT) called DT2219ARL consisting of two scFv ligands recognizing CD19 and CD22 and catalytic DT390 was genetically enhanced for superior in vivo anti-leukemia activity. Genetic alterations included reverse orienting VH-VL domains and adding aggregation reducing/stabilizing linkers. In vivo, these improvements resulted in previously unseen long-term tumor-free survivors measured in a bioluminescent xenograft imaging model in which the progression of human Raji Burkitt's lymphoma could be tracked in real time and in a Daudi model as well. Studies showed DT2219ARL was potent (IC50s 0.06-0.2 nM range) and selectively blockable. Imaging studies indicated the highly invasive nature of this B cell malignancy model and showed it likely induced pre-terminal hind limb paralysis because of metastasis to spinal regions prevented by DT2219ARL. DT2219ARL represents a new class of bispecific biological that can be continually improved by genetic mutation.
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Li Q, Hapka D, Chen H, Vallera DA, Wagner CR. Self-assembly of antibodies by chemical induction. Angew Chem Int Ed Engl 2009; 47:10179-82. [PMID: 19025747 DOI: 10.1002/anie.200803507] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Vallera DA, Stish BJ, Shu Y, Chen H, Saluja A, Buchsbaum DJ, Vickers SM. Genetically designing a more potent antipancreatic cancer agent by simultaneously co-targeting human IL13 and EGF receptors in a mouse xenograft model. Gut 2008; 57:634-41. [PMID: 18222985 PMCID: PMC2756191 DOI: 10.1136/gut.2007.137802] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Investigators are currently interested in the epidermal growth factor receptor (EGFR) and interleukin 13 receptor (IL13R) as potential targets in the development of new biologicals for pancreatic cancer. Attempts to develop successful agents have met with difficulty. The novel approach used here was to target these receptors simultaneously with EGF and IL13 cloned on the same bispecific single-chain molecule with truncated diphtheria toxin (DT(390)) to determine if co-targeting with DTEGF13 had any advantages. DESIGN Proliferation experiments were performed to measure the potency and selectivity of bispecific DTEGF13 and its monospecific counterparts against pancreatic cancer cell lines PANC-1 and MiaPaCa-2 in vitro. DTEGF13 was then administered intratumourally to nude mice with MiaPaCa-2 flank tumours to measure efficacy and toxicity (weight loss). RESULTS In vitro, bispecific DTEGF13 was 2800-fold more toxic than monospecific DTEGF or DTIL13 against PANC-1. A similar enhancement was observed in vitro when MiaPaCa-2 pancreatic cancer cells or H2981-T3 lung adenocarcinoma cells were studied. DTEGF13 activity was blockable with recombinant EGF13. DTEGF13 was potent (IC(50) = 0.00017 nM) against MiaPaCa-2, receptor specific and significantly inhibited MiaPaCa-2 tumours in nude mice (p<0.008). CONCLUSIONS In vitro studies show that the presence of both ligands on the same bispecific molecule is responsible for the superior activity of DTEGF13. Intratumoural administration showed that DTEGF13 was highly effective in checking aggressive tumour progression in mice. Lack of weight loss in these mice indicated that the drug was tolerated and a therapeutic index exists in an "on target" model in which DTEGF13 is cross-reactive with native mouse receptors.
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Stish BJ, Chen H, Shu Y, Panoskaltsis-Mortari A, Vallera DA. A bispecific recombinant cytotoxin (DTEGF13) targeting human interleukin-13 and epidermal growth factor receptors in a mouse xenograft model of prostate cancer. Clin Cancer Res 2008; 13:6486-93. [PMID: 17975161 DOI: 10.1158/1078-0432.ccr-07-0938] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Overexpressed cytokine receptors are considered valid targets for new biologicals targeting prostate cancer. However, current reagents are limited in efficacy. Our goal was to determine the advantages of simultaneously targeting two established targets, epidermal growth factor receptor and interleukin-13 (IL-13) receptor, with a new bispecific cytotoxin in which both EGF and IL-13 cytokines were cloned onto the same single-chain molecule with truncated diphtheria toxin (DT(390)). EXPERIMENTAL DESIGN In vitro experiments measured the potency of bispecific DTEGF13 and compared its activity to its monospecific counterparts, DTEGF and DTIL13. We determined whether the presence of both cytokine ligands on the same molecule was responsible for its superior activity. In vivo, DTEGF13 was given i.t. to athymic nude mice with established PC-3 human prostate cancer tumor xenografts on their flanks. RESULTS In vitro, DTEGF13 was more potent than the monospecific cytotoxins against human prostate cancer lines. Enhanced activity was related to the presence of both cytokines on the same single-chain molecule and was not attributed to enhanced binding capacity. Killing was receptor specific. Cytotoxicity could be blocked with anti-EGF and anti-IL-13 antibodies. In vivo, DTEGF13, but not monospecific DTEGF or DTIL13, significantly inhibited the growth of established PC-3 tumors in nude mice (P < 0.0001). CONCLUSIONS These data show for the first time that simultaneous targeting of cytokine receptors with two ligands on the same molecule has pronounced anticancer advantages. In an animal model in which human DTEGF13 is cross-reactive with mouse, DTEGF13 was highly effective in checking aggressive prostate tumor progression and was reasonably tolerated.
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Stish BJ, Chen H, Shu Y, Panoskaltsis-Mortari A, Vallera DA. Increasing anticarcinoma activity of an anti-erbB2 recombinant immunotoxin by the addition of an anti-EpCAM sFv. Clin Cancer Res 2007; 13:3058-67. [PMID: 17505009 DOI: 10.1158/1078-0432.ccr-06-2454] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE erbB2, the product of the Her2-neu gene, is a well-established therapeutic target for antibody-based biologicals, but anti-erbB2 antibody-toxin fusion proteins are limited in their activity. The goal of this study was to determine if genetically adding an sFv targeting epithelial cell adhesion molecule (EpCAM) to an anti-Her2 sFv immunotoxin would result in enhanced antitumor activity. EXPERIMENTAL DESIGN In vitro studies were done in which the new bispecific immunotoxin DTEpCAM23 was compared with monospecific immunotoxins (DTEpCAM and DT23) to quantitate immunotoxin activity. Mixtures of monospecific immunotoxins were tested to determine if they were as effective as the bispecific immunotoxin. Binding and internalization studies were also done. In vivo, bispecific immunotoxins were given i.t. to athymic nude mice bearing HT-29 human colon cancer flank tumors and i.p. to mice with i.p. tumors. RESULTS DTEpCAM23 bispecific immunotoxins showed far greater activity than monospecific immunotoxin (sometimes over 2,000-fold) against most tumor lines. Bispecific immunotoxin was superior and selective in its activity against different carcinoma cell lines. Bispecific immunotoxin had greater activity than monospecific immunotoxin indicating an advantage of having both sFv on the same single-chain molecule. Binding and internalization studies did not explain the differences between bispecific immunotoxin and monospecific immunotoxin activity. Orientation of the sFvs on the molecule had a significant effect on in vitro and in vivo properties. The bispecific immunotoxins were more effective than the monospecific immunotoxin in the flank tumor mouse model. CONCLUSIONS The synthesis of bispecific immunotoxin created a new biological agent with superior in vitro and in vivo activity (over monospecific immunotoxin), more broad reactivity, more efficacy against tumors in vivo, and diminished toxic effects in mice.
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Vallera DA, Sicheneder AR, Taras EP, Brechbiel MW, Vallera JA, Panoskaltsis-Mortari A, Burns LJ. Radiotherapy of CD45-Expressing Daudi Tumors in Nude Mice with Yttrium-90-Labeled, PEGylated Anti-CD45 Antibody. Cancer Biother Radiopharm 2007; 22:488-500. [PMID: 17803443 DOI: 10.1089/cbr.2007.366] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Studies were performed to determine the suitability of using the polyethylene glycol (PEG)-labeled AHN-12 anti-CD45 monoclonal antibody to deliver the high-energy beta-particle-emitting isotope 90Y to a CD45+ B-cell Daudi lymphoma grown as flank tumors in athymic nude mice. The PEGylated radiolabeled antibody displayed a significantly better antitumor effect in the mouse tumor flank model (p<0.03) and significantly better blood pharmacokinetics in normal rats (p<0.05) than the non-PEGylated radiolabeled antibody. Studies of two different sizes of PEG showed that rats given 43 kDa of PEGylated AHN-12, but not 5 kDa of PEGylated AHN-12, had significantly higher radiolabeled antibody blood levels and, therefore, improved pharmacokinetics, as compared to rodents given non-PEGylated radiolabeled AHN-12 (p<0.05). Surviving mice revealed no signs of kidney, liver, or gastrointestinal damage by histology study. Notably, in vitro studies indicated that PEGylation did not have a major effect on labeling efficiency and the binding of labeled antibody. These findings indicate that PEGylation of radiolabeled anti-CD45 antibody may be a useful and desirable means of extending blood half-life and enhancing efficacy. Also, the final outcome may be impacted by the size of the PEG molecule used for the modification of the blood half-life.
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Rustamzadeh E, Hall WA, Todhunter DA, Vallera VD, Low WC, Liu H, Panoskaltsis-Mortari A, Vallera DA. Intracranial therapy of glioblastoma with the fusion protein DTAT in immunodeficient mice. Int J Cancer 2007; 120:411-9. [PMID: 17075792 DOI: 10.1002/ijc.22278] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A gene splicing technique was used to create a hybrid fusion protein DTAT encoding the 390 amino acid portion of diphtheria toxin (DT(390)), a linker, and the downstream 135-amino terminal fragment portion of human urokinase plasminogen activator. DTAT was assembled to target human glioblastoma cell lines in a murine intracranial model. Previously published in vitro studies demonstrated that DTAT was highly selective and toxic to human glioblastoma cell lines in a flank tumor model. The purpose of this study was to determine the toxicity, specificity and possible therapeutic efficacy of DTAT in an intracranial model. Convection enhanced delivery of DTAT resulted in about a 16-fold increase in maximum tolerated dose. Intracranial administration of DTAT on an every-other-day basis in nude mice with established U87 MG brain tumors resulted in significant reductions in tumor volume and significantly prolonged survival (p < 0.0001). Magnetic resonance imaging proved to be a powerful tool in mice and rats for demonstrating tumor growth in a xenograft intracranial model, assessing the efficacy of DTAT in tumor volume reduction and detecting DTAT-associated intracranial toxicity and vascular damage. These results suggest that the DTAT recombinant fusion protein is highly effective in an intracranial model and DTAT might be an effective treatment for glioblastoma.
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Rustamzadeh E, Vallera DA, Todhunter DA, Low WC, Panoskaltsis-Mortari A, Hall WA. Immunotoxin pharmacokinetics: a comparison of the anti-glioblastoma bi-specific fusion protein (DTAT13) to DTAT and DTIL13. J Neurooncol 2006; 77:257-66. [PMID: 16314943 DOI: 10.1007/s11060-005-9051-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
DTAT13, a novel recombinant bispecific immunotoxin (IT) consisting of truncated diphtheria toxin, an amino-terminal (AT) fragment of the urokinase-type plasminogen activator (uPa), and a fragment of human IL-13 was assembled in order to target receptors on glioblastoma multiforme (GBM) and its associated neovasculature. Previous in vitro studies confirmed the efficacy of DTAT13 against various GBM cell lines expressing both IL-13 receptor or uPA receptor, and previous in vivo testing demonstrated the efficacy of DTAT13 in significantly inhibiting a range of xenograft tumors and showed that DTAT13 was 160- and 8-fold less toxic to the parental fusion IT, DTAT and DTIL13, respectively. To further understand the properties of DTAT13, pharmacokinetic/biodistribution experiments were performed. Binding analysis revealed that the IL-13 domain functioned independently of the uPA domain and that the K (d) for each binding domain was essentially the same as that of DTIL13 and DTAT. Flow cytometry studies indicated that DTAT13 bound better than DTAT or DTIL13. Analysis of the rate of protein synthesis inhibition in U87 MG cells by DTAT13 compared to DTAT revealed a faster rate of inhibition with DTAT13 compared to DTAT. The rate of protein synthesis inhibition of DTAT13 was identical to that of DTIL13 in U373 MG cells. Intracranial biodistribution studies revealed that DTAT13 was able to cross to the contralateral hemisphere unlike DTIL13 but similar to DTAT. These studies show that DTAT13 has properties encompassing those of both DTIL13 and DTAT and warrants further consideration for clinical development.
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Abstract
OBJECT Because the prognosis for patients with glioblastoma multiforme (GBM) remains poor, investigators have focused on developing new and more effective treatment modalities. Targeted toxins represent a new class of compounds composed of a potent protein toxin and a carrier ligand that will recognize cell surface antigens located on target tissue. A recombinant fusion protein was created that contains the translocation and catalytic portions of diphtheria toxin that are responsible for cell entry and killing, respectively, fused to the noninternalizing aminoterminal fragment portion of human plasminogen activator. This diptheria toxin-uPA fusion protein (DTAT) has the advantage over other fusion proteins of targeting malignant glioma cells and the endothelial cells of the neovasculature that express the urokinase-type plasminogen activator receptor (uPAR). Another protein, DTAT13, was synthesized to target uPAR on the neovasculature and the uPAR and interleukin-13 receptor-expressing GBM cells. The authors describe the in vitro and in vivo efficacy of DTAT and DTAT13 against GBM. METHODS The in vitro cytotoxicity of DTAT and DTAT13 was measured using cell proliferation assays. In vivo studies were performed in which DTAT, DTAT13, or a control protein was injected directly into GBM flank tumors in athymic nude mice. Tumor volume was assessed over time and analyzed using the Student t-test. The systemic organ effects of DTAT and DTAT13 were examined functionally and histologically in tumor-free C57BL/6 mice. In vitro, DTAT and DTAT13 were found to be highly potent and selective against U118MG, U87MG, and U373MG GBM cell lines and human umbilical vein endothelial cells. In vivo, DTAT and DTAT13 both caused a statistically significant (p < 0.05) regression of U87MG GBM flank tumors when administered every other day at 10 mg/day for five doses. No tumor regression was seen in control animals. Both DTAT and DTAT13 had little effect on histological findings in the liver, kidney, spleen, and lungs. Serum analysis did not demonstrate an effect on blood urea nitrogen levels, but liver alanine aminotransferase levels rose to statistically significant (p = 0.046) but not life-threatening levels. Also, DTAT13 was less toxic than DTAT in studies of mortality rates. CONCLUSIONS Both DTAT and DTAT13 might have potential for clinical application against GBM because of their ability to target both the tumor cells and neovasculature simultaneously with an absence of serious systemic side effects. The discovery that DTAT13 was less toxic than DTAT indicated that the bispecific fusion protein might target a broader subset of antigenetically diverse patients with tumors while reducing the systemic exposure to toxin that would be necessary if two agents were administered separately.
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MESH Headings
- Angiogenesis Inhibitors/chemical synthesis
- Angiogenesis Inhibitors/pharmacology
- Angiogenesis Inhibitors/therapeutic use
- Animals
- Antineoplastic Agents/chemical synthesis
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Bacterial Toxins/pharmacology
- Bacterial Toxins/therapeutic use
- Brain Neoplasms/blood supply
- Brain Neoplasms/drug therapy
- Brain Neoplasms/physiopathology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cytotoxins/chemical synthesis
- Cytotoxins/pharmacology
- Cytotoxins/therapeutic use
- Disease Models, Animal
- Female
- Glioblastoma/blood supply
- Glioblastoma/drug therapy
- Glioblastoma/physiopathology
- Humans
- Interleukin-13 Receptor alpha1 Subunit
- Liver/drug effects
- Liver/enzymology
- Mice
- Mice, Inbred C57BL
- Mice, Nude
- Molecular Weight
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/physiopathology
- Neovascularization, Pathologic/prevention & control
- Oncogene Proteins, Fusion/chemical synthesis
- Oncogene Proteins, Fusion/pharmacology
- Oncogene Proteins, Fusion/therapeutic use
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/metabolism
- Receptors, Interleukin/drug effects
- Receptors, Interleukin/metabolism
- Receptors, Interleukin-13
- Receptors, Urokinase Plasminogen Activator
- Recombinant Fusion Proteins/chemical synthesis
- Recombinant Fusion Proteins/pharmacology
- Recombinant Fusion Proteins/therapeutic use
- Treatment Outcome
- Urokinase-Type Plasminogen Activator/chemistry
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Vallera DA, Brechbiel MW, Burns LJ, Panoskaltsis-Mortari A, Dusenbery KE, Clohisy DR, Vitetta ES. Radioimmunotherapy of CD22-expressing Daudi tumors in nude mice with a 90Y-labeled anti-CD22 monoclonal antibody. Clin Cancer Res 2006; 11:7920-8. [PMID: 16278417 DOI: 10.1158/1078-0432.ccr-05-0725] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A study was undertaken to investigate the efficacy of a high affinity, rapidly internalizing anti-CD22 monoclonal antibody for selectively delivering high-energy (90)Y radioactivity to B lymphoma cells in vivo. The antibody, RFB4, was readily labeled with (90)Y using the highly stable chelate, 1B4M-diethylenetriaminepentaacetic acid. Labeled RFB4 selectively bound to the CD22(+) Burkitt's lymphoma cell line Daudi, but not to CD22(-) control cells in vitro as compared with a control antibody, and was more significantly bound (P = 0.03) to Daudi solid tumors growing in athymic nude mice. Biodistribution data correlated well with the antitumor effect. The therapeutic effect of (90)Y-labeled anti-CD22 (Y22) was dose-dependent, irreversible, and the best results were achieved in mice receiving a single i.p. dose of 196 microCi. These mice displayed a significantly better (P < 0.01) antitumor response than control mice and survived >200 days with no evidence of tumor. Histology studies showed no significant injury to kidney, liver, or small intestine. Importantly, tumor-bearing mice treated with Y22 had no radiologic bone marrow damage compared with tumor-bearing mice treated with the control-labeled antibody arguing that the presence of CD22(+) tumor protected mice from bone marrow damage. When anti-CD22 radioimmunotherapy was compared to radioimmunotherapy with anti-CD19 and anti-CD45 antibodies, all three antibodies distributed significantly high levels of radioisotope to flank tumors in vivo compared with controls (P < 0.05), induced complete remission, and produced long-term, tumor-free survivors. These findings indicate that anti-CD22 radioimmunotherapy with Y22 is highly effective in vivo against CD22-expressing malignancies and may be a useful therapy for drug-refractory B cell leukemia patients.
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Rustamzadeh E, Hall WA, Todhunter DA, Low WC, Liu H, Panoskaltsis-Mortari A, Vallera DA. Intracranial therapy of glioblastoma with the fusion protein DTIL13 in immunodeficient mice. Int J Cancer 2006; 118:2594-601. [PMID: 16358262 DOI: 10.1002/ijc.21647] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A fusion protein consisting of human interleukin-13 and the first 389 amino acids of diphtheria toxin was assembled in order to target human glioblastoma cell lines in a murine intracranial model. In vitro studies to determine specificity indicated that the protein called DTIL13 was highly selective for human glioblastoma. In vivo, the maximum tolerated dose of DTIL13 was 1 microg/injection given every other day and repeated for 3 days. Doses that exceeded this amount resulted in weight loss and liver damage as determined by histology and enzyme assay. Experiments in IL-4 receptor knockout mice revealed that liver toxicity was receptor-related. This same dose given to nude mice with established U373 MG brain tumors resulted in significant reductions in tumor volume and significantly prolonged survival (p<0.0001). Magnetic resonance imaging (MRI) proved to be extremely useful in (i) determining the ability of DTIL13 to reduce tumor size and (ii) for studying toxicity since diffusion-weighted and gradient echo-weighted MRI revealed that vascular leak syndrome was not a limiting toxicity at this dose. These results suggest that DTIL13 is as effective in an intracranial rodent model as it was in a flank model in previous studies and that DTIL13 might be an effective treatment for glioblastoma multiforme.
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Vallera DA, Todhunter DA, Kuroki DW, Shu Y, Sicheneder A, Chen H. A bispecific recombinant immunotoxin, DT2219, targeting human CD19 and CD22 receptors in a mouse xenograft model of B-cell leukemia/lymphoma. Clin Cancer Res 2005; 11:3879-88. [PMID: 15897589 DOI: 10.1158/1078-0432.ccr-04-2290] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A novel bispecific single-chain fusion protein, DT2219, was assembled consisting of the catalytic and translocation domains of diphtheria toxin (DT(390)) fused to two repeating sFv subunits recognizing CD19 and CD22 and expressed in Escherichia coli. Problems with yield, purity, and aggregation in the refolding step were solved by incorporating a segment of human muscle aldolase and by using a sodium N-lauroyl-sarcosine detergent-based refolding procedure. Problems with reduced efficacy were addressed by combining the anti-CD19 and anti-CD22 on the same single-chain molecule. DT2219 had greater anticancer activity than monomeric or bivalent immunotoxins made with anti-CD19 and anti-CD22 sFv alone and it showed a higher level of binding to patient leukemia cells and to CD19(+)CD22(+) Daudi or Raji cells than did anti-CD19 and anti-CD22 parental monoclonal antibodies. The resulting DT2219, mutated to enhance its avidity, was cytotoxic to Daudi cells in vitro (IC(50) = 0.3 nmol/L). In vivo, DT2219 was effective in a flank tumor therapy model in which it significantly inhibited tumor growth (P < 0.05) and in a systemic model in which it significantly prolonged survival of severe combined immunodeficient mice with established Daudi (P < 0.008) compared with controls. DT2219 has broader reactivity in recognizing B-cell malignancies, has more killing power, and requires less toxin than using individual immunotoxin, which warrants further investigation as a new drug for treating B leukemia/lymphoma.
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MESH Headings
- Animals
- Antibodies
- Antigens, CD/immunology
- Antigens, CD19/immunology
- Antigens, Differentiation, B-Lymphocyte/immunology
- Cell Adhesion Molecules/immunology
- Cell Death
- Diphtheria Toxin/immunology
- Escherichia coli/genetics
- Escherichia coli/immunology
- Female
- Immunotoxins/immunology
- Immunotoxins/pharmacology
- Lectins/immunology
- Leukemia, B-Cell
- Lymphoma, B-Cell
- Mice
- Mice, Nude
- Mice, SCID
- Molecular Conformation
- Sialic Acid Binding Ig-like Lectin 2
- Survival Analysis
- Transplantation, Heterologous
- Tumor Cells, Cultured
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Vallera DA, Todhunter D, Kuroki DW, Shu Y, Sicheneder A, Panoskaltsis-Mortari A, Vallera VD, Chen H. Molecular modification of a recombinant, bivalent anti-human CD3 immunotoxin (Bic3) results in reduced in vivo toxicity in mice. Leuk Res 2005; 29:331-41. [PMID: 15661270 DOI: 10.1016/j.leukres.2004.08.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 08/17/2004] [Indexed: 10/26/2022]
Abstract
A novel bivalent single chain fusion protein, Bic3, was assembled consisting of the catalytic and translocation domains of diphtheria toxin (DT(390)) fused to two repeating sFv molecules recognizing human CD3 epsilon of the human T-cell receptor. Historically, problems with these constructs include low yield, toxicity, and reduced efficacy. Instead of using conventional Gly(4)Ser linkers to connect heavy/light chains, aggregation reducing linkers (ARL) were used which when combined with a new SLS-based refolding method reduced aggregation and enhanced the yield of final product. Toxicity was reduced at least 25-fold by repeating the two sFv molecules and adding a portion of the hinge-CH2-CH3 human constant regions. The resulting Bic3 was just as cytotoxic to HPB-MLT.UM T leukemia cells in vitro (IC(50)=4 pmol) as a monovalent construct made with the same DT and sFv. In vivo, Bic3 was effective in a new and aggressive therapy model in which it significantly prolonged survival of scid mice with established human T-cell leukemia (p<0.0001 compared to controls). Importantly, no toxicity measured by weight loss, enzyme function, or histology was observed at the highest dose of Bic3 tested (2000 ug/kg). Bic3 warrants investigation as a new drug for treating T-cell malignancy and other T-cell related disorders.
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Vallera DA, Elson M, Brechbiel MW, Dusenbery KE, Burns LJ, Jaszcz WB, Ramsay NK, Panoskaltsis-Mortar A, Kuroki DW, Wagner JE, Vitetta ES, Kersey JH. Radiotherapy of CD19 expressing Daudi tumors in nude mice with Yttrium-90-labeled anti-CD19 antibody. Cancer Biother Radiopharm 2004; 19:11-23. [PMID: 15068607 DOI: 10.1089/108497804773391630] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Studies were performed to determine the suitability of using two different anti-CD19 monoclonal antibodies to deliver the high energy beta-particle emitting isotope 90Y to B-cell lymphoma grown as flank tumors in athymic nude mice. The antibodies BU12 and HD37, both of the IgG1 subclass, recognize CD19, an internalizing B-lineage-specific membrane glycoprotein and member of the Ig supergene family. The antibodies were readily labeled with 90Y using the highly stable chelate, 1B4M-MX-DTPA. The radioimmunoconjugates selectively bound to the CD19 expressing B cell line Daudi, but not to CD19 negative control cells. Significantly more 90Y anti-CD19 bound to Daudi tumors growing in nude mice than did a control non-binding antibody (p = 0.001). The biodistribution data correlated with an anti-tumor effect. Anti-tumor activity was dose dependent and the best results were observed in mice receiving a single dose of approximately 300 uCi. The anti-CD19 antibody had significantly better anti-tumor activity as compared to a control 90Y-labeled antibody and most mice survived over 119 days with no evidence of tumor (p < 0.003). Histology studies showed no significant injury to the kidney, liver, or small intestine. Because radiolabeled anti-CD19 antibody can be used to deliver radiation selectively to lymphohematopoietic tissue, these data support the use of 90Y anti-CD19 antibodies in treating B-cell malignancies.
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67
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Todhunter DA, Hall WA, Rustamzadeh E, Shu Y, Doumbia SO, Vallera DA. A bispecific immunotoxin (DTAT13) targeting human IL-13 receptor (IL-13R) and urokinase-type plasminogen activator receptor (uPAR) in a mouse xenograft model. Protein Eng Des Sel 2004; 17:157-64. [PMID: 15047912 DOI: 10.1093/protein/gzh023] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A bispecific immunotoxin (IT) called DTAT13 was synthesized in order to target simultaneously the urokinase-type plasminogen activator receptor (uPAR)-expressing tumor neovasculature and IL-13 receptor expressing glioblastoma cells with the goal of intratumoral administration for brain tumors. The recombinant hybrid was created using the non-internalizing N-terminal fragment (ATF) of uPA and the IL-13 molecule for binding plus the catalytic and translocation portion of diphtheria toxin (DT) for killing. The 71 kDa protein was highly selective for human glioblastoma in vitro showing no loss on binding compared with DTAT and DTIL13 controls. In vivo, DTAT13 caused the regression of small tumors when administered at 10 micro g/day given on a five-dose schedule every other day. DTAT13 was able to target both overexpressed uPAR and the vasculature, as demonstrated by its ability to kill HUVEC cells. Also, mortality studies indicated that DTAT13 was less toxic than DTAT or DTIL13. These findings indicate that bispecific IT may allow treatment of a broader subset of antigenically diverse patients while simultaneously reducing the exposure to toxin required than if two separate agents were employed.
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MESH Headings
- Animals
- Antibodies, Bispecific
- Antineoplastic Agents/adverse effects
- Antineoplastic Agents/pharmacology
- Binding Sites
- Cell Division/drug effects
- Cells, Cultured
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Female
- Glioblastoma/drug therapy
- Humans
- Immunotoxins/genetics
- Immunotoxins/immunology
- Immunotoxins/pharmacology
- Interleukin-13/genetics
- Interleukin-13/metabolism
- Interleukin-13 Receptor alpha1 Subunit
- Kidney/drug effects
- Mice
- Mice, Nude
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Peptide Fragments
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/metabolism
- Receptors, Interleukin/metabolism
- Receptors, Interleukin-13
- Receptors, Urokinase Plasminogen Activator
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/immunology
- Recombinant Fusion Proteins/isolation & purification
- Recombinant Fusion Proteins/pharmacology
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/pharmacology
- Toxicity Tests
- Xenograft Model Antitumor Assays
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68
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Rustamzadeh E, Li C, Doumbia S, Hall WA, Vallera DA. Targeting the over-expressed urokinase-type plasminogen activator receptor on glioblastoma multiforme. J Neurooncol 2004; 65:63-75. [PMID: 14649886 DOI: 10.1023/a:1026238331739] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A recombinant fusion protein targeting the urokinase-type plasminogen activator receptor (uPAR) and delivering a potent catalytic toxin has the advantage of simultaneously targeting both over-expressed uPAR on glioblastoma cells and on the tumor neovasculature. Such a hybrid protein was synthesized consisting of the noninternalizing amino-terminal fragment (ATF) of urokinase-type plasminogen activator (uPA) for binding, and the catalytic portion of diphtheria toxin (DT) for killing, and the translocation enhancing region (TER) of DT for internalization. The protein was highly selective for human glioblastoma in vitro and in vivo. In vivo, this DT/ATF hybrid called DTAT caused the regression of small subcutaneous uPAR-expressing tumors with minimal toxicity to critical organs. In vitro, DTAT killed only uPAR-positive glioblastoma cell lines and human endothelial cells in the form of the HUVEC cell line. Killing was selective and blockable with specific antibody. DTAT was highly effective against tumor cells cultured from glioblastoma multiforme patients and in vitro mixing experiments combining DTAT with DTIL13 another highly effective anti-glioblastoma agent showed that the mixture was as toxic as the most potent immunotoxin. In this article, we review our progress to date with DTAT.
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69
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Vallera DA, Jin N, Shu Y, Panoskaltsis-Mortari A, Kelekar A, Chen W. Retroviral Immunotoxin Gene Therapy of Leukemia in Mice Using Leukemia-Specific T Cells Transduced with an Interleukin-3/Bax Fusion Protein Gene. Hum Gene Ther 2003; 14:1787-98. [PMID: 14670129 DOI: 10.1089/104303403322611791] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In past studies, we showed that T cells transduced with retroviral diphtheria immunotoxin (IT) target genes could serve as vehicles for delivering IT to tumors in vivo. We took advantage of the observation that antigen-specific T cells are able to penetrate tumors to design an approach delivering combined cellular and humoral therapy directly to the tumor site. To improve tumor specificity, we selected interleukin (IL)-3 as a ligand because its receptor is selectively overexpressed on myeloid leukemia progenitors. Because Bcl-2 family proteins show structural similarity to diphtheria toxin (DT), we constructed a unique retroviral IT using Bax, a proapoptotic member of the Bcl-2 family, in place of DT. Bax was chosen because several studies showed that its transduction induces lethal apoptosis in different cancers. The retroviral construct for gene therapy included IL-3 positioned downstream of its 80 amino acid leader, and permitted cotranslational protein synthesis of hybrid IL-3/human Bax fusion protein. Other vectors were constructed with IL-3 fused to DT or Pseudomonas exotoxin. Retroviral vectors were used to transiently transduce C8, a CD4(+) T cell clone that specifically recognized FBL-3, a lethal myeloid leukemia. Supernatants collected from transduced cells showed proapoptotic activity and selectively inhibited FBL-3 cells in vitro. Intraperitoneal injection of transduced but not nontransduced C8 into mice with subcutaneous tumors or systemic cancer significantly inhibited tumor growth. These results indicate that retroviral IT made with IL-3 and various toxic proteins may be useful in patients with acute myelogenous leukemia (AML). Furthermore, the Bax construct may be particularly useful as a nonimmunogenic substitute for bacterial toxins in retIT.
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70
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Abstract
Surgery, chemotherapy, and radiation therapy have become standard of practice in treating malignant brain tumors. Unfortunately, the prognosis of these malignant tumors still remains poor. Immunotoxins are a relatively new adjuvant treatment for brain tumors. Within the last few years an increased amount of clinically-oriented research involving immunotoxins has been published. This has led to numerous clinical trials which although encouraging have not yet born out the "magic bullet" concept envisioned for immunotoxins. In this review article the history, design, toxicity, and pharmokinetics of immunotoxins will be discussed in detail.
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71
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Vallera DA, Elson M, Brechbiel MW, Dusenbery KE, Burns LJ, Skubitz KM, Jaszcz WB, Ramsay NK, Panoskaltsis-Mortari A, Kuroki DW, Wagner JE, Kersey JH. Preclinical studies targeting normal and leukemic hematopoietic cells with Yttrium-90-labeled anti-CD45 antibody in vitro and in vivo in nude mice. Cancer Biother Radiopharm 2003; 18:133-45. [PMID: 12804039 DOI: 10.1089/108497803765036300] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A study was undertaken to investigate the suitability of using a high affinity (Kd = 1.1 nM) anti-CD45 monoclonal antibody for delivering the high energy beta-particle emitting isotope (90)Y to lymphohematopoietic target cells in vivo. The antibody, AHN-12, recognized the tyrosine phosphatase CD45 expressed on the surface of normal and malignant hematopoietic cells and studies showed that it reacted with both CD45-expressing normal peripheral blood cells and leukemia cells from patients. The antibody was readily labeled with (90)Y using the highly stable chelate 1B4M-DTPA and the radioimmunoconjugate was designated (90)Y-anti-CD45. The agent selectively bound to CD45(+) B cell line Daudi, but not CD45(-) control cells and significantly (p = 0.007) more bound to Daudi tumors growing in athymic nude mice than did a control non-reactive antibody. Moreover, biodistribution data correlated well to an anti-Daudi effect observed against established tumors in nude mice. The effect was dose dependent and irreversible with the best results in mice receiving a single dose of 137 microCi (90)Y-anti-CD45. These mice displayed a significantly (p < 0.0095) better anti-tumor effect than a control (90)Y-labeled antibody and survived over 135 days with no evidence of tumor. Histology studies showed no significant injury to kidney, liver, or small intestine even at 254 microCi, the highest dose tested. Because radiolabeled anti-CD45 antibody can be used to deliver radiation selectively to lymphohematopoietic tissue, these data indicate that this agent may be used to improve treatment of hematopoietic malignancies, particularly leukemia and lymphoma, when combined with hematopoietic stem cell transplantation in a future clinical trial.
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Ramage JG, Vallera DA, Black JH, Aplan PD, Kees UR, Frankel AE. The diphtheria toxin/urokinase fusion protein (DTAT) is selectively toxic to CD87 expressing leukemic cells. Leuk Res 2003; 27:79-84. [PMID: 12479856 DOI: 10.1016/s0145-2126(02)00077-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Diphtheria fusion proteins are a novel class of agents for the treatment of chemotherapy resistant acute myelogenous leukemia (AML). We prepared diphtheria toxin/urokinase fusion protein (DTAT) composed of the amino terminal fragment of the urokinase-type plasminogen activator (uPA) fused to the catalytic and translocation domains of diphtheria toxin (DT) and assessed its activity on leukemic cell lines. The number of uPA receptors (uPAR or CD87) was measured using a phycoerythrin conjugated monoclonal antibody to CD87 and flow cytometry. Seven of 23 cell lines (30%) showed CD87 expression (> or =5000 receptors/cell). DTAT cytotoxicity (IC(50)< or =30pM) was observed in all seven of these samples and none of the 16 samples with low or absent CD87 expression. There was a significant correlation between DTAT sensitivity and CD87 density (P=0.0007). These results show that specific CD87 binding is one factor important in the sensitivity of patient's leukemic blasts to DTAT and demonstrate for the first time that the CD87/uPAR can be used as a target for fusion protein therapy of AML.
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MESH Headings
- Acute Disease
- Antineoplastic Agents/chemistry
- Antineoplastic Agents/pharmacology
- Blast Crisis/pathology
- Burkitt Lymphoma/pathology
- Flow Cytometry
- HL-60 Cells/drug effects
- Humans
- Jurkat Cells/drug effects
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Leukemia, Myeloid/pathology
- Leukemia-Lymphoma, Adult T-Cell/pathology
- Multiple Myeloma/pathology
- Neoplasm Proteins/drug effects
- Neoplasm Proteins/physiology
- Neoplastic Stem Cells/drug effects
- Neoplastic Stem Cells/metabolism
- Oncogene Proteins, Fusion/pharmacology
- Protein Structure, Tertiary
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/physiology
- Receptors, Urokinase Plasminogen Activator
- Recombinant Fusion Proteins/pharmacology
- U937 Cells/drug effects
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73
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Rustamzadeh E, Low WC, Vallera DA, Hall WA. J Neurooncol 2003; 64:101-116. [DOI: 10.1023/a:1024906516075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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74
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Frankel AE, Beran M, Hogge DE, Powell BL, Thorburn A, Chen YQ, Vallera DA. Malignant progenitors from patients with CD87+ acute myelogenous leukemia are sensitive to a diphtheria toxin-urokinase fusion protein. Exp Hematol 2002; 30:1316-23. [PMID: 12423685 DOI: 10.1016/s0301-472x(02)00925-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In previous studies, we demonstrated that the diphtheria toxin-urokinase fusion protein DTAT was selectively toxic to acute myeloid leukemia (AML) cell lines overexpressing the CD87 urokinase receptor. In the present study, we analyzed the sensitivity of patient leukemic progenitors to DTAT and correlated the sensitivity with CD87 expression. We isolated leukemic blasts by density gradient centrifugation and performed immunophenotyping by flow cytometry and blast sensitivity measurements by inhibition of cell proliferation and colony formation in semisolid media. We found CD87 overexpression in 18 (25%) of 71 patient leukemic blast samples, including 18 (28%) of 64 myeloid malignancies and 0 (0%) of 7 lymphoid malignancies. DTAT was toxic to patient leukemic blasts by both proliferation inhibition (IC50 <or=1 nM DTAT in 18/69 evaluable samples) and colony formation inhibition (>85% inhibition by 10 nM DTAT in 11/41 evaluable samples). Only AML and chronic myeloid leukemia (CML) blast crisis blasts (18/61 [30%]) were sensitive to DTAT by the proliferation inhibition assay. Lymphoid leukemia and chronic phase CML/chronic myelomonocytic leukemia (CMML) progenitors were insensitive to DTAT by the proliferation inhibition assay (n = 7 and n = 3, respectively). Similarly, normal marrow progenitors were insensitive to DTAT by both proliferation inhibition (n = 2) and colony inhibition (n = 5) assays. The DTAT toxicity measured by both proliferation inhibition assay and colony inhibition assay correlated with CD87 density (p < 0.0001 and p = 0.001, respectively). DTAT toxicity results were similar for leukemic blasts measured by either of the two assays (p = 0.0002). This study provides the first evidence that a urokinase receptor targeted diphtheria fusion protein is toxic to patient AML blasts. The work also suggests that blast proliferation assays yield similar responses to leukemia colony-forming cell colony assays.
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75
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Li C, Hall WA, Jin N, Todhunter DA, Panoskaltsis-Mortari A, Vallera DA. Targeting glioblastoma multiforme with an IL-13/diphtheria toxin fusion protein in vitro and in vivo in nude mice. Protein Eng Des Sel 2002; 15:419-27. [PMID: 12034862 DOI: 10.1093/protein/15.5.419] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fusion proteins composed of tumor binding agents and potent catalytic toxins show promise for intracranial therapy of brain cancer and an advantage over systemic therapy. Glioblastoma multiforme (GBM) is the most common form of brain cancer and overexpresses IL-13R. Thus, we developed an interleukin-13 receptor targeting fusion protein, DT(390)IL13, composed of human interleukin-13 and the first 389 amino acids of diphtheria toxin. To measure its ability to inhibit GBM, DT(390)IL13 was tested in vitro and found to inhibit selectively the U373 MG GBM cell line with an IC(50) around 12 pmol/l. Cytotoxicity was neutralized by anti-human-interleukin-13 antibody, but not by control antibodies. In vivo, small U373 MG glioblastoma xenografts in nude mice completely regressed in most animals after five intratumoral injections of 1 microg of DT(390)IL13 q.o.d., but not by the control fusion protein DT(390)IL-2. DT(390)IL13 was also tested against primary explant GBM cells of a patient's excised tumor and the IC(50) was similar to that measured for U373 MG. Further studies showed a therapeutic window for DT(390)IL13 of 1-30 microg/injection and histology studies and enzyme measurements showed that the maximum tolerated dose of DT(390)IL13 had little effect on kidney, liver, spleen, lung and heart in non-tumor-bearing immunocompetent mice. Together, these data suggest that DT(390)IL13 may provide an important, alternative therapy for brain cancer.
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