Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.

Immunotoxins are antibody-toxin fusion proteins directed to kill cancer cells displaying specific target antigens on their surface. Remarkably, immunotoxins directed to CD22 on hairy cell leukemia have produced complete remissions in approximately 60% of patients enrolled in phase I/II trials. For r...

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Main Authors: Fitzgerald, D, Moskatel, E, Ben-Josef, G, Traini, R, Tendler, T, Sharma, A, Antignani, A, Mussai, F, Wayne, A, Kreitman, R, Pastan, I
Format: Journal article
Language:English
Published: 2011
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author Fitzgerald, D
Moskatel, E
Ben-Josef, G
Traini, R
Tendler, T
Sharma, A
Antignani, A
Mussai, F
Wayne, A
Kreitman, R
Pastan, I
author_facet Fitzgerald, D
Moskatel, E
Ben-Josef, G
Traini, R
Tendler, T
Sharma, A
Antignani, A
Mussai, F
Wayne, A
Kreitman, R
Pastan, I
author_sort Fitzgerald, D
collection OXFORD
description Immunotoxins are antibody-toxin fusion proteins directed to kill cancer cells displaying specific target antigens on their surface. Remarkably, immunotoxins directed to CD22 on hairy cell leukemia have produced complete remissions in approximately 60% of patients enrolled in phase I/II trials. For reasons that are not yet clear, 40% of patients responded less well. In addition, patients with other CD22-positive malignancies have not yet achieved complete remissions. In trying to understand 'resistance' to immunotoxin therapy, a number of challenging issues have been raised. These include insufficient dosing, the production of neutralizing anti-immunotoxin antibodies, poor access to malignant cells, and resistance to toxin killing. In designing immunotoxins, we employ truncated Pseudomonas exotoxin, which enzymatically inactivates protein synthesis and produces cell death in sensitive cells. To begin to address toxin resistance we have explored combination therapy with the BH3-only mimetic, ABT-737. Our results indicate that immunotoxin-ABT combinations often exhibit greater killing activity than either compound alone and in some instances overcome resistance. Expression of high levels of prosurvival Bcl-2 proteins may contribute to toxin resistance.
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spelling oxford-uuid:6b7d6ce9-2c69-42bc-9312-d393814eb2312022-03-26T19:04:28ZEnhancing immunotoxin cell-killing activity via combination therapy with ABT-737.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6b7d6ce9-2c69-42bc-9312-d393814eb231EnglishSymplectic Elements at Oxford2011Fitzgerald, DMoskatel, EBen-Josef, GTraini, RTendler, TSharma, AAntignani, AMussai, FWayne, AKreitman, RPastan, IImmunotoxins are antibody-toxin fusion proteins directed to kill cancer cells displaying specific target antigens on their surface. Remarkably, immunotoxins directed to CD22 on hairy cell leukemia have produced complete remissions in approximately 60% of patients enrolled in phase I/II trials. For reasons that are not yet clear, 40% of patients responded less well. In addition, patients with other CD22-positive malignancies have not yet achieved complete remissions. In trying to understand 'resistance' to immunotoxin therapy, a number of challenging issues have been raised. These include insufficient dosing, the production of neutralizing anti-immunotoxin antibodies, poor access to malignant cells, and resistance to toxin killing. In designing immunotoxins, we employ truncated Pseudomonas exotoxin, which enzymatically inactivates protein synthesis and produces cell death in sensitive cells. To begin to address toxin resistance we have explored combination therapy with the BH3-only mimetic, ABT-737. Our results indicate that immunotoxin-ABT combinations often exhibit greater killing activity than either compound alone and in some instances overcome resistance. Expression of high levels of prosurvival Bcl-2 proteins may contribute to toxin resistance.
spellingShingle Fitzgerald, D
Moskatel, E
Ben-Josef, G
Traini, R
Tendler, T
Sharma, A
Antignani, A
Mussai, F
Wayne, A
Kreitman, R
Pastan, I
Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title_full Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title_fullStr Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title_full_unstemmed Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title_short Enhancing immunotoxin cell-killing activity via combination therapy with ABT-737.
title_sort enhancing immunotoxin cell killing activity via combination therapy with abt 737
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