EANM  Spain, 1999

RADIOIMMUNOTHERAPY OF SCID MICE BEARING HUMAN B-CELL LYMPHOMA USING I-131 LABELED ANTI-CD20 MONOCLONAL ANTIBODY

N. Oriuchi, T. Higuchi, S. Alyafei, H. Zhang, Y. Nakasone, N. Watanabe, H. Kanda, M. Hashimoto, T. Inoue, K. Endo.

Department of Nuclear Medicine, Gunma University School of Medicine, Japan.

The anti-tumor efficacy and toxicity of I-131 labeled anti-CD 20 monoclonal antibody was evaluated in severely combined immunodeficiency (SCID) mice and compared with chemotherapy using doxorubicin hydrochloride (DOX) or cis-diamminedichloroplatinum (CDDP). Monoclonal antibody designated NuB2 is an IgG1 of murine origin that binds to CD20 which is expressed on B-cell lymphoma NuB2 was produced for clinical use and labeled with I-131 by a sterile procedure. Cell binding assay was performed using a CD-20 positive human B-cell lymphoma cell line RPMI1788. RPMI1788 sells were inoculated into the abdominal wall of female SCID mice. When tumors had grown to 6 mm in diameter, groups of 5 mice were injected I.V. with 100uCi or 200uCi of I-131 labeled NuB2, unlabeled NuB2, 67ug or 100ug of DOX, 100ug or 150ug of CDDP. Tumors were measured until they grew to 18mm. The anti-tumor effect was expressed as the absolute growth delay, which was defined as the time in days required for the tumors in the treat group to grow from 6mm to 12 mm minus the time required for control tumors to grow. I-131 labeled NuB2 demonstrated up to 80% binding to RPMI1788 cells, indicating retainment of immunoreactivity. In the groups of 200uCi I-131 NuB2, 100ug ADR, and 150ug CDDP, two mice or more died of side effect. Absolute growth delay of 100uCi I-131 labeled NuB2, unlabeled NuB2, 67ug ADR, 100 ug CDDP was 4, 2, 4, 2 days, respectively. I-131 labeled NuB2 showed anti-tumor effect comparable to 67 ug ADR and greater than 100ug CDDP. Unlabeled NuB2 also showed some anti-tumor effect. These results indicate that a novel anti-CD20 monoclonal may be effective for radioimmunotherapy of B-cell lymphoma.

PMID: , UI: