Recombinant anti-CD25 immunotoxin RFT5(SCFV)-ETA' demonstrates successful elimination of disseminated human Hodgkin lymphoma in SCID mice
✍ Scribed by Stefan Barth; Michael Huhn; Bärbel Matthey; Roland Schnell; Samir Tawadros; Timo Schinköthe; Johann Lorenzen; Volker Diehl; Andreas Engert
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- French
- Weight
- 284 KB
- Volume
- 86
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
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-sizechromatography. 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 g 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 ␣ was 39.65 min, the serum elimination time T 1/2 ␣, 756.6 min. All animals were assessed for soluble interleukin-2 receptor ␣, 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.