Overexpression of CD85j in TNBC patients inhibits Cetuximab‐mediated NK‐cell ADCC but can be restored with CD85j functional blockade

Abstract

Clinical studies suggest that triple negative breast cancer (TNBC) patients with epidermal growth factor receptor (EGFR)-expressing tumors could benefit from therapy withCetuximab, which targets EGFR. NK cells are the primary effectors of antibody (Ab)-dependent cell-mediated cytotoxicity (ADCC) and thus play a role in Ab-based therapies. We have previously described diminished levels of Cetuximab-mediated ADCC in vitro in patients with advanced breast cancer. Here, we investigated the potential causes of this NK-cell functional deficiency. We characterized NK-cell activating/inhibitory receptors in the peripheral blood of breast cancer patients and found CD85j inhibitory receptor overexpression. The capacity of NK cells to perform Cetuximab-triggered ADCC against TNBC cells correlated inversely with CD85j expression, even in the presence of the stimulatory cytokines IL-2 or IL-15. Hence, patients expressing high levels of CD85j had an impaired ability to lyse TNBC cells in the presence of Cetuximab. We also found that CD85j overexpression was associated with HLA-I and soluble HLA-G expression by tumors. A CD85j functional blockade with a CD85j antagonist Ab restored ADCC levels in breast cancer patients and reverted this negative effect. Our data suggest that strategies that overcome the hurdles of immune activation could improve Cetuximab clinical efficacy.Keywords: ADCC r CD85j r Cetuximab r EGFR r NK cells r Triple negative breast cancer Additional supporting information may be found in the online version of this article at the publisher's web-site Introduction NK cells are a major component of the innate immune system and can limit the growth and dissemination of several types of Correspondence: Dr. Estrella M. Levy e-mail: estrellamlevy@yahoo.com.ar tumors [1]. In cancer immune surveillance, NK cells can exert direct cellular cytotoxicity on tumor cells without prior sensitization and secrete immunostimulatory cytokines such as IFN-γ, which can control both local tumor growth and metastasis [2,3]. Moreover, NK cells act as effectors in Ab-dependent cell-mediated cytotoxicity (ADCC) [4]. Accordingly, it has been determined that NK-cell activity can play a significant role [13]. LIR-1, the most broadly expressed LIR family member, is an inhibitory receptor that binds multiple MHC-I molecules, both classical (HLA-A, -B, and -C) and nonclassical (HLA-E, -F, and -G) [12][13][14][15][16]. The inhibitory receptor LIR-1 (also known as ILT-2 and CD85j) is the only LIR expressed on NK cells [17]. Upon ligand binding, CD85j is able to inhibit NK-cell cytotoxicity [16,[18][19][20], as well as IFN-γ production [21]. Despite the fact that NK-cell inhibitory receptor engagement with target cells is considered a primary event in the formation of the inhibitory synapse and the subsequent prevention of cell lysis [22], CD85j receptor involvement in cancer has been poorly addressed. In lung cancer, CD85j expression was drastically reduced on intratumoral NK cells compared to blood NK cells [23]. In contrast, CD85j was upreg...

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“…Mean 6 SEM were plotted in (B). ****p , 0.0001. cytotoxicity and this effect can be reversed by CD85j blockade (34). Thus, M2 may generate hyporesponsive NK cells with impaired immunosurveillance capacity.…”

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The Expanding Spectrum of Ligands for Leukocyte Ig-like Receptors

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