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Recombinant anti‐CD25 immunotoxin RFT5(SCFV)‐ETA' demonstrates successful elimination of disseminated human Hodgkin lymphoma in SCID mice
Author(s) -
Barth Stefan,
Huhn Michael,
Matthey Bärbel,
Schnell Roland,
Tawadros Samir,
Schinköthe Timo,
Lorenzen Johann,
Diehl Volker,
Engert Andreas
Publication year - 2000
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/(sici)1097-0215(20000601)86:5<718::aid-ijc18>3.0.co;2-n
Subject(s) - immunotoxin , pseudomonas exotoxin , recombinant dna , lymphoma , exotoxin , microbiology and biotechnology , medicine , monoclonal antibody , immunology , virology , antibody , biology , toxin , biochemistry , gene
Since clinical phase‐I/II trials in patients with resistant Hodgkin's lymphoma treated with the chemically linked anti‐CD25 ricin‐A‐chain immunotoxin RFT5‐SMPT‐dgA indicate promising results for patients with minimal residual disease, we constructed a new immunotoxin by fusing the RFT5 single‐chain variable fragment to a deletion mutant of Pseudomonas exotoxin A (ETA'). The recombinant protein was directed into the periplasmic space of E. coli by means of the pET‐derived expression vector pBM1.1 and our newly developed expression/purification method. Biologically active RFT5(scFv)‐ETA' was isolated by freezing/thawing and purified by immobilized metal‐ion affinity and molecular‐size‐chromatography. RFT5(scFv)‐ETA' was subsequently used for the treatment of disseminated human Hodgkin's lymphoma in a SCID‐mouse model. The mean survival time (MST) of L540rec‐challenged SCID mice was 38.1 days. A single i.v. injection of 40 μg recombinant immunotoxin (rIT) 1 day after tumor inoculation resulted in 100% tumor‐free mice, extending the MST to more than 220 days ( p < 0.0001). The blood‐distribution time T 1/2 α was 39.65 min, the serum elimination time T 1/2 α, 756.6 min. All animals were assessed for soluble interleukin‐2 receptor α, which is directly correlated to tumor burden. Soluble CD25 was not detectable in mice treated with the rIT. Our findings, concerning potent anti‐tumor effects of a recombinant anti‐CD25 immunotoxin against disseminated Hodgkin's lymphoma in SCID mice reported here demonstrate that RFT5(scFv)‐ETA' might be suitable for further evaluation against Hodgkin's lymphoma in humans. Int. J. Cancer 86:718–724, 2000. © 2000 Wiley‐Liss, Inc.