Rider DA, Havenith CEG, de Ridder R, Schuurman J, Favre C, Cooper JC, Walker S, Baadsgaard O, Marschner S, vandeWinkel JGJ, Cambier J, Parren PWHI, Alexander DR. A human CD4 monoclonal antibody for the treatment of T-cell lymphoma combines inhibition of T-cell signaling by a dual mechanism with potent Fc-dependent effector activity.
Cancer Res 2007;
67:9945-53. [PMID:
17942927 DOI:
10.1158/0008-5472.can-07-1148]
[Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Zanolimumab is a human IgG1 antibody against CD4, which is in clinical development for the treatment of cutaneous and nodal T-cell lymphomas. Here, we report on its mechanisms of action. Zanolimumab was found to inhibit CD4+ T cells by combining signaling inhibition with the induction of Fc-dependent effector mechanisms. First, T-cell receptor (TCR) signal transduction is inhibited by zanolimumab through a fast, dual mechanism, which is activated within minutes. Ligation of CD4 by zanolimumab effectively inhibits early TCR signaling events but, interestingly, activates signaling through the CD4-associated tyrosine kinase p56lck. An uncoupling of p56lck from the TCR by anti-CD4 allows the kinase to transmit direct inhibitory signals via the inhibitory adaptor molecules Dok-1 and SHIP-1. Second, CD4+ T cells are killed by induction of antibody-dependent cell-mediated cytotoxicity, to which CD45RO+ cells are more sensitive than CD45RA+ cells. Finally, zanolimumab induces down-modulation of CD4 from cell surfaces via a slow Fc-dependent mechanism. In conclusion, zanolimumab rapidly inhibits T-cell signaling via a dual mechanism of action combined with potent Fc-dependent lysis of CD4+ T cells and may act long-term by down-regulating CD4.
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