We first proposed that the IL-2 receptor was an interesting target for immunotherapy. Many workers have now validated the power of anti-CD25 mAb treatment in preclinical models. Five different anti-CD25 mAbs are immunosuppressive in clinical practice. Since rodent anti-human mAbs are poor cytocidal agents in man, we also proposed that the ideal therapeutic molecule for targeting the IL-2R would be a IL-2 toxin fusion protein. Our preclinical results support this hypothesis; however, we now aim to improve the potency of the IL-2 toxin-through protein engineering. It is critical that information be gained from these preclinical models before IL-2 toxin be employed as an immunosuppressive agent in man. In phase I-II clinical trials, the first IL-2 toxin has proven remarkably safe and potent in the elimination of IL-2R+ leukemic cells - even in patients bearing high titer, neutralizing anti-diphtheria toxoid antibodies. Unlike applications for cancer, the IL-2 toxin must compete for occupancy of the IL-2R with locally released IL-2 for successful treatment of GVHD. GVHD is resistant to the first generation IL-2 toxin. Our work outline follows: A. Protein engineering of IL-2-toxin. a. Analysis of DAB-IL-2 sequences that are required for maximal cytotoxic potency and optimal binding to the low, intermediate, and high affinity form of the IL-2 receptor.i. analysis of diphtheria toxin fragment B sequences between Thr387 and His485.i. deletion mutagenesis; ii. analysis of interleukin-2 sequences required for optimal binding to the high affinity form of the IL-2 receptor. i. site-directed mutagenesis b. Protein engineering of the region of the fusion junction between diphtheria toxin fragment B and human IL-2 sequences. i. insertion mutagenesis B. Determination of the potency of modified IL-2-toxin to cause 1. immunosuppression to conventional antigens 2. tolerance in murine GVHD models.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI022882-07
Application #
3134528
Study Section
Experimental Immunology Study Section (EI)
Project Start
1985-12-01
Project End
1995-05-31
Budget Start
1993-06-01
Budget End
1994-05-31
Support Year
7
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Beth Israel Deaconess Medical Center
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02215
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