Antitumor activity of the single-chain immunotoxin BR96 sFv-PE40 against established breast and lung tumor xenografts.

Abstract

We have constructed a single-chain immunotoxin consisting of the variable H and L chains of the carcinoma-reactive mAb BR96, fused to the binding defective protein toxin, PE40. This molecule, BR96 sFv-PE40, has been shown to be extremely cytotoxic toward a variety of BR96 Ag-expressing tumor cell lines. When administered i.v. into athymic mice carrying L2987 tumor xenografts, BR96 sFv-PE40 was cleared rapidly from the blood with a half-life of approximately 30 min. This is in comparison to a chemical conjugate, chiBR96-LysPE40, that remained in the blood for almost 2 h. In addition, the smaller single-chain immunotoxin (67 kDa) penetrates the tumor faster than the larger chemical conjugate (190 kDa). Using a variety of administration schedules and doses, we treated established human tumor xenografts in athymic mice with both the single-chain immunotoxin BR96 sFv-PE40 and the chemical conjugate chiBR96-LysPE40. In both L2987 lung carcinoma and MCF-7 breast carcinoma models, we found that BR96 sFv-PE40 completely regressed the tumor xenografts. With an administration schedule of q4dx5, the tumors were totally regressed and did not reappear. The chiBR96-LysPE40 conjugate produced partial tumor regressions, although at near maximum tolerated dose. These results show that the single-chain immunotoxin, BR96 sFv-PE40, is a potent antitumor agent.

• Authors: P N Friedman, D F Chace, P A Trail, C B Siegall
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 150 Issue 7 Pg. 3054-61 (Apr 01 1993) ISSN: 0022-1767 [Print] United States
• PMID: 8454873 (Publication Type: Journal Article)

Chemical References

• Antibodies, Monoclonal
• Antineoplastic Agents
• BR96 sFv-PE40
• Bacterial Toxins
• Exotoxins
• Immunotoxins
• Recombinant Fusion Proteins
• Virulence Factors
• ADP Ribose Transferases
• Pseudomonas aeruginosa exotoxin A

Topics

• ADP Ribose Transferases
• Animals
• Antibodies, Monoclonal (therapeutic use, toxicity)
• Antineoplastic Agents (pharmacology, toxicity)
• Bacterial Toxins
• Exotoxins (therapeutic use, toxicity)
• Female
• Humans
• Immunotoxins (therapeutic use, toxicity)
• Lung Neoplasms (therapy)
• Mammary Neoplasms, Experimental (therapy)
• Mice
• Mice, Nude
• Neoplasm Transplantation
• Pseudomonas aeruginosa (chemistry, genetics, immunology)
• Recombinant Fusion Proteins (therapeutic use, toxicity)
• Structure-Activity Relationship
• Tissue Distribution
• Virulence Factors