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High CD21 expression inhibits internalization of anti-CD19 antibodies and cytotoxicity of an anti-CD19-drug conjugate

CD19 and CD21 (CR2) are co-receptors found on B-cells and various B-cell lymphomas, including non-Hodgkin lymphoma. To evaluate their suitability as targets for therapy of such lymphomas using internalization-dependent antibody-drug conjugates [such as antibody-4-(N-maleimidomethyl)cyclohexane-1-car...

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Detalles Bibliográficos
Autores principales: Ingle, Gladys S, Chan, Pamela, Elliott, J Michael, Chang, Wesley S, Koeppen, Hartmut, Stephan, Jean-Philippe, Scales, Suzie J
Formato: Texto
Lenguaje:English
Publicado: Blackwell Publishing Ltd 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228374/
https://www.ncbi.nlm.nih.gov/pubmed/17991300
http://dx.doi.org/10.1111/j.1365-2141.2007.06883.x
Descripción
Sumario:CD19 and CD21 (CR2) are co-receptors found on B-cells and various B-cell lymphomas, including non-Hodgkin lymphoma. To evaluate their suitability as targets for therapy of such lymphomas using internalization-dependent antibody-drug conjugates [such as antibody-4-(N-maleimidomethyl)cyclohexane-1-carboxylate, (N(2′)-deacetyl-N(2′)-(3-mercapto-1-oxopropyl)-maytansine) (MCC-DM1) conjugates, which require lysosomal degradation of the antibody moiety for efficacy], we examined uptake of antibodies to CD19 and CD21 in a panel of B-cell lines. Anti-CD21 antibodies were not sufficiently internalized even in the highest CD21-expressing Raji cells, resulting in lack of efficacy with anti-CD21-MCC-DM1 conjugates. Anti-CD19 antibody uptake was variable, and was unexpectedly negatively correlated with CD21 expression. Thus, high CD21-expressing Raji, ARH77 and primary B-cells only very slowly internalized anti-CD19 antibodies, while CD21-negative or low expressing cells, including Ramos and Daudi, rapidly internalized these antibodies in clathrin-coated vesicles followed by lysosomal delivery. Anti-CD19-MCC-DM1 caused greater cytotoxicity in the faster anti-CD19-internalizing cell lines, implying that the rate of lysosomal delivery and subsequent drug release is important. Furthermore, transfection of Ramos cells with CD21 impeded anti-CD19 uptake and decreased anti-CD19-MCC-DM1 efficacy, suggesting that CD21-negative tumours should respond better to such anti-CD19 conjugates. This may have possible clinical implications, as anti-CD21 immunohistochemistry revealed only approximately 30% of 54 diffuse large B-cell lymphoma patients lack CD21 expression.