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Title: Targeting primary human Ph(+) B-cell precursor leukemia-engrafted SCID mice using radiolabeled anti-CD19 monoclonal antibodies.
Austin Authors: Mitchell, Paul L R ;Lee, Fook-Thean;Hall, Cathrine;Rigopoulos, Angela;Smyth, Fiona E;Hekman, Anne-Marie;van Schijndel, Gijs M;Powles, Ray;Brechbiel, Martin W;Scott, Andrew M 
Affiliation: Ludwig Institute For Cancer Research, Melbourne Tumour Biology Branch, Austin and Repatriation Medical Centre, Melbourne, Victoria, Australia
Issue Date: 1-Jul-2003
Publication information: Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine; 44(7): 1105-12
Abstract: The Philadelphia chromosome translocation (Ph(+)) confers a poor prognosis in patients with acute lymphocytic leukemia (ALL). CD19 is highly expressed (CD19(+)) on ALL cells and is an attractive target for antibody-based therapies. CLB-CD19 is an IgG1kappa murine monoclonal antibody (mAb) directed against an epitope on the CD19 antigen.Radiolabeled CLB-CD19 antibody was evaluated for targeting ALL in a severe combined immunodeficient (SCID) mouse model engrafted with primary human leukemia cells. Lodgment of CD19(+) ALL cells in spleen and liver was confirmed using immunohistochemistry analyses. Circulating CD19(+) ALL cells in blood were also detected by flow cytometry.Antibody was labeled directly with the radiohalogen (125)I and radiometal (111)In via the bifunctional metal ion chelate CHX-A"-diethylenetriaminepentaacetic acid (DTPA) with retention of immunoreactivities. After intravenous injection of radioconjugates, biodistribution studies showed rapid localization of the (111)In-conjugate to leukemia-infiltrated spleen, reaching a maximum (mean +/- SD) of 72.78 +/- 13.67 % injected dose per gram of tissue (%ID/g) by 24 h after injection. In contrast, peak localization of coinjected (125)I-CLB-CD19 occurred by 4 h and was significantly lower (11.41 +/- 12.79 %ID/g) (P < 0.001). Uptake of (111)In-conjugate in the liver containing tumor was also evident but not in other normal tissues. Uptake of radiolabeled CLB-CD19 in tumor-bearing organs was specific, as uptake of radiolabeled isotype-matched antibody control was low. Gamma-camera imaging detected the uptake of (111)In-CHX-A"-DTPA CLB-CD19 in enlarged tumor-bearing spleen of engrafted mice. A single injection of 32 micro g CLB-CD19 mAb had a delayed suppressive effect on the level of circulatory leukemia cells in surviving mice and extended the median survival from 48.5 to 58 d (n = 8; P = 0.03).The radiolabeled anti-CD19 antibody showed specific targeting and rapid internalization in ALL cell-engrafted SCID mice and may also be used for selective intracellular delivery of cytotoxic radionuclides with beta-, Auger, or alpha-emissions.
Gov't Doc #: 12843229
Type: Journal Article
Subjects: Animals
Antibodies, Monoclonal.chemistry.pharmacokinetics
Antigens, CD19.metabolism
Indium Radioisotopes.pharmacokinetics
Iodine Radioisotopes.pharmacokinetics
Isotope Labeling.methods
Leukemia, Myelogenous, Chronic, BCR-ABL Positive.metabolism.pathology.radionuclide imaging
Mice, SCID
Neoplasm Transplantation
Precursor Cell Lymphoblastic Leukemia-Lymphoma.metabolism.pathology.radionuclide imaging
Recombinant Proteins.chemistry.pharmacokinetics
Splenic Neoplasms.metabolism
Tissue Distribution
Tumor Markers, Biological.metabolism
Appears in Collections:Journal articles

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