Efficient killing of CD22{sup +} tumor cells by a humanized diabody-RNase fusion protein
- Department of Medical Oncology and Cancer Research, University of Essen, D-45122 Essen (Germany)
- Institute of Immunology, University of Essen, D-45122 Essen (Germany)
- SAIC, National Cancer Institute at Frederick, Frederick, MD 21702 (United States)
- Developmental Therapeutics Program, National Cancer Institute at Frederick, Frederick, MD 21702 (United States)
We report on the generation of a dimeric immunoenzyme capable of simultaneously delivering two ribonuclease (RNase) effector domains on one molecule to CD22{sup +} tumor cells. As targeting moiety a diabody derived from the previously humanized scFv SGIII with grafted specificity of the murine anti-CD22 mAb RFB4 was constructed. Further engineering the interface of this construct (V{sub L}36{sub Leu{yields}}{sub Tyr}) resulted in a highly robust bivalent molecule that retained the same high affinity as the murine mAb RFB4 (K{sub D} 0.2 nM). A dimeric immunoenzyme comprising this diabody and Rana pipiens liver ribonuclease I (rapLRI) was generated, expressed as soluble protein in bacteria, and purified to homogeneity. The dimeric fusion protein killed several CD22{sup +} tumor cell lines with high efficacy (IC{sub 50} = 3-20 nM) and exhibited 9- to 48-fold stronger cytotoxicity than a monovalent rapLRI-scFv counterpart. Our results demonstrate that engineering of dimeric antibody-ribonuclease fusion proteins can markedly enhance their biological efficacy.
- OSTI ID:
- 20709218
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 331, Issue 2; Other Information: DOI: 10.1016/j.bbrc.2005.03.215; PII: S0006-291X(05)00731-X; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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