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Asgarov K, Balland J, Tirole C, Bouard A, Mougey V, Ramos D, Barroso A, Zangiacomi V, Jary M, Kim S, Gonzalez-Pajuelo M, Royer B, de Haard H, Clark A, Wijdenes J, Borg C. A new anti-mesothelin antibody targets selectively the membrane-associated form. MAbs 2017; 9:567-577. [PMID: 28353419 DOI: 10.1080/19420862.2017.1288770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mesothelin is a glycosylphosphatidylinositol (GPI)-anchored membrane protein that shows promise as a target for antibody-directed cancer therapy. High levels of soluble forms of the antigen represent a barrier to directing therapy to cellular targets. The ability to develop antibodies that can selectively discriminate between membrane-bound and soluble conformations of a specific protein, and thus target only the membrane-associated antigen, is a substantive issue. We show that use of a tolerance protocol provides a route to such discrimination. Mice were tolerized with soluble mesothelin and a second round of immunizations was performed using mesothelin transfected P815 cells. RNA extracted from splenocytes was used in phage display to obtain mesothelin-specific antigen-binding fragments (Fabs) that were subsequently screened by flow cytometry and ELISA. This approach generated 147 different Fabs in 34 VH-CDR3 families. Utilizing competition assays with soluble protein and mesothelin-containing serum obtained from metastatic cancer patients, 10 of these 34 VH-CDR3 families were found to bind exclusively to the membrane-associated form of mesothelin. Epitope mapping performed for the 1H7 clone showed that it does not recognize GPI anchor. VH-CDR3 sequence analysis of all Fabs showed significant differences between Fabs selective for the membrane-associated form of the antigen and those that recognize both membrane bound and soluble forms. This work demonstrates the potential to generate an antibody specific to the membrane-bound form of mesothelin. 1H7 offers potential for therapeutic application against mesothelin-bearing tumors, which would be largely unaffected by the presence of the soluble antigen.
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Affiliation(s)
- Kamal Asgarov
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France
| | - Jeremy Balland
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France
| | - Charline Tirole
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France
| | - Adeline Bouard
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France
| | - Virginie Mougey
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,c Blood Bank Bourgogne-Franche-comté , Porto , Portugal
| | | | | | - Vincent Zangiacomi
- b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France
| | - Marine Jary
- e J.Minjoz University Hospital , Besançon Cedex , France
| | - Stefano Kim
- e J.Minjoz University Hospital , Besançon Cedex , France
| | | | - Bernard Royer
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France.,e J.Minjoz University Hospital , Besançon Cedex , France
| | | | | | | | - Christophe Borg
- a University of Bourgogne-Franche-Comte , Besançon Cedex , France.,b ITAC Platform of Clinical Investigation Center-Biotherapy , Besançon Cedex , France.,c Blood Bank Bourgogne-Franche-comté , Porto , Portugal.,e J.Minjoz University Hospital , Besançon Cedex , France
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