A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells.
We have engineered an anti-carcinoembryonic antigen (CEA) single-chain immunotoxin derived from humanized anti-CEA antibody (hMN14) and a truncated Pseudomonas exotoxin (PE), PE40. The purified anti-CEA immunotoxin (hMN14(Fv)-PE40) was first measured for binding affinity against a CEA-positive color...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
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1998
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| _version_ | 1797058727191248896 |
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| author | Akamatsu, Y Murphy, J Nolan, K Thomas, P Kreitman, R Leung, S Junghans, R |
| author_facet | Akamatsu, Y Murphy, J Nolan, K Thomas, P Kreitman, R Leung, S Junghans, R |
| author_sort | Akamatsu, Y |
| collection | OXFORD |
| description | We have engineered an anti-carcinoembryonic antigen (CEA) single-chain immunotoxin derived from humanized anti-CEA antibody (hMN14) and a truncated Pseudomonas exotoxin (PE), PE40. The purified anti-CEA immunotoxin (hMN14(Fv)-PE40) was first measured for binding affinity against a CEA-positive colorectal carcinoma cell line and compared with its parental IgG and the monovalent Fab fragment. The Ka of sFv-PE40, Fab, and IgG were 5 x 10(7), 6 x 10(7), and 3 x 10(8) M(-1), respectively. There was no significant affinity loss by conversion of Fab to the single-chain Fv, but these monovalent forms were 5-6-fold reduced in affinity compared with the parental IgG. In cytotoxicity assays, the hMN14(Fv)-PE40 showed specific growth suppression of CEA-expressing colon cancer cell lines MIP-CEA (high CEA) and LS174T (moderate CEA) with IC50s of 12 ng/ml (0.2 nM) and 69 ng/ml (1.1 nM). These IC50s correlated inversely with the surface expression of CEA, such that 50% killing was equivalent for each cell type when expressed in toxin molecules bound/cell (3000-5000). The presence of soluble CEA up to 1000 ng/ml did not affect the cytotoxicity against CEA-expressing cells, with 50% suppression only at 4000 ng/ml that correlated with the binding Kd of the single-chain Fv. The stability of the hMN14(Fv)-PE40 molecule at 37 degrees C was confirmed by bioassay and by lack of aggregation. Our hMN14(Fv)-PE40 may be clinically useful for tumors with high CEA expression without affecting normal tissues with low or absent CEA, even in patients with high soluble antigen levels. |
| first_indexed | 2024-03-06T19:54:23Z |
| format | Journal article |
| id | oxford-uuid:250f685d-c377-4c01-a9ee-3d822f2c5847 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T19:54:23Z |
| publishDate | 1998 |
| record_format | dspace |
| spelling | oxford-uuid:250f685d-c377-4c01-a9ee-3d822f2c58472022-03-26T11:53:36ZA single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:250f685d-c377-4c01-a9ee-3d822f2c5847EnglishSymplectic Elements at Oxford1998Akamatsu, YMurphy, JNolan, KThomas, PKreitman, RLeung, SJunghans, RWe have engineered an anti-carcinoembryonic antigen (CEA) single-chain immunotoxin derived from humanized anti-CEA antibody (hMN14) and a truncated Pseudomonas exotoxin (PE), PE40. The purified anti-CEA immunotoxin (hMN14(Fv)-PE40) was first measured for binding affinity against a CEA-positive colorectal carcinoma cell line and compared with its parental IgG and the monovalent Fab fragment. The Ka of sFv-PE40, Fab, and IgG were 5 x 10(7), 6 x 10(7), and 3 x 10(8) M(-1), respectively. There was no significant affinity loss by conversion of Fab to the single-chain Fv, but these monovalent forms were 5-6-fold reduced in affinity compared with the parental IgG. In cytotoxicity assays, the hMN14(Fv)-PE40 showed specific growth suppression of CEA-expressing colon cancer cell lines MIP-CEA (high CEA) and LS174T (moderate CEA) with IC50s of 12 ng/ml (0.2 nM) and 69 ng/ml (1.1 nM). These IC50s correlated inversely with the surface expression of CEA, such that 50% killing was equivalent for each cell type when expressed in toxin molecules bound/cell (3000-5000). The presence of soluble CEA up to 1000 ng/ml did not affect the cytotoxicity against CEA-expressing cells, with 50% suppression only at 4000 ng/ml that correlated with the binding Kd of the single-chain Fv. The stability of the hMN14(Fv)-PE40 molecule at 37 degrees C was confirmed by bioassay and by lack of aggregation. Our hMN14(Fv)-PE40 may be clinically useful for tumors with high CEA expression without affecting normal tissues with low or absent CEA, even in patients with high soluble antigen levels. |
| spellingShingle | Akamatsu, Y Murphy, J Nolan, K Thomas, P Kreitman, R Leung, S Junghans, R A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title | A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title_full | A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title_fullStr | A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title_full_unstemmed | A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title_short | A single-chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells. |
| title_sort | single chain immunotoxin against carcinoembryonic antigen that suppresses growth of colorectal carcinoma cells |
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