An Anti-MICA/B Antibody and IL-15 Rescue Altered NKG2D-Dependent NK Cell Responses in Hepatocellular Carcinoma

Abstract

Natural killer (NK) cells play a pivotal role in cancer immune surveillance, and activating the receptor/ligand interaction may contribute to control the development and evolution of hepatocellular carcinoma (HCC). We investigated the role of the natural killer group 2 member D (NKG2D) activating receptor and its ligand, the major histocompatibility complex class I chain-related protein A and B (MICA/B) in patients with cirrhosis and HCC subjected to surgical resection, patients with cirrhosis and no HCC, and healthy donors (HD). The NKG2D-mediated function was determined in peripheral blood (PB), in tumor-infiltrating lymphocytes (NK-TIL), and in matched surrounding liver tissue (NK-LIL). A group of patients treated with sorafenib because of clinically advanced HCC was also studied. A humanized anti-MICA/B monoclonal antibody (mAb) was used in in vitro experiments to examine NK cell-mediated antibody-dependent cellular cytotoxicity. Serum concentrations of soluble MICA/B were evaluated by ELISA. IL-15 stimulation increased NKG2D-dependent activity which, however, remained dysfunctional in PB NK cells from HCC patients, in line with the reduced NKG2D expression on NK cells. NK-TIL showed a lower degranulation ability than NK-LIL, which was restored by IL-15 stimulation. Moreover, in vitro IL-15 stimulation enhanced degranulation and interferon-γ production by PB NK from patients at month one of treatment with sorafenib. Anti-MICA/B mAb associated with IL-15 was able to induce PB NK cytotoxicity for primary HCC cells in HD and patients with HCC, who also showed NK-TIL degranulation for autologous primary HCC cells. Our findings highlight the key role of the NKG2D-MICA/B axis in the regulation of NK cell responses in HCC and provide evidence in support of a potentially important role of anti-MICA/B mAb and IL-15 stimulation in HCC immunotherapy.

MICA/B-targeted antibody promotes NK cell–driven tumor immunity in patients with intrahepatic cholangiocarcinoma

“…Zhou et al 53 observed lower proportions of cytotoxic T cells, NK cells and increased regulatory T cells by immunohistochemistry in iCCA tumors. Notably, reduced frequencies of NKG2D+ NK cells have been observed by our group in HCC 27 and by others in non-hepatic tumors. 32 , 58 Here we showed that NKG2D activating receptor expression was indeed reduced in PBMC and tumor-infiltrating NK cells making them potentially unsuitable for optimal engagement of MICA/B proteins expressed on tumor cells.…”

“…Since the release of MICA/B proteins by tumor cells and the concomitant increase of their soluble form are thought to represent a mechanism of immune escape evading NK immune surveillance in several neoplastic settings 38 , 39 including HCC, 27 , 40 we measured serum MICA in iCCA patients. As shown in Figure 2a , sMICA was higher in iCCA patients compared with HC.…”

“…We previously demonstrated elevated sMICA levels in sera from HCC patients, which stratified according to tumor grade. 27 Even though sMICA was also elevated in the setting of iCCA, it was not possible to reveal differences according to tumor grade.…”

Defucosylation of Tumor-Specific Humanized Anti-MUC1 Monoclonal Antibody Enhances NK Cell-Mediated Anti-Tumor Cell Cytotoxicity

“…Still, lower baseline levels of CD16 correlate with decreased ADCC responses in NK cells: compared with NK cells obtained from healthy donors, it was demonstrated that NK cells from cancer patients showed a significant reduction of both direct killing and ADCC against tumors, which was due to CD16 down-regulation [ 58 ]. In cancer patients, the expression levels of CD16, DNAM-1, and NKG2D have also been reported down-regulation on NK cells [ 59 , 60 ]. A Western blot assay using NK cells after stimulation with tumor cells may further add proof to possible CD16 shedding.…”

Leveraging NKG2D Ligands in Immuno-Oncology

“…Also, 7C6 acts synergistically with the HDACi panobinostat through stabilizing tumor cell surface MICA/B expression ( 224 ) and exhibits synergy with human cytokine-induced NK cells (CIK) in vitro ( 225 ). A different humanized anti-MICA/B mAb stimulates NK cell-mediated cytotoxicity in vitro against primary hepatocellular carcinoma cells ( 226 ). In addition, three novel mAb (5E10, 7G10 and 6E1) that recognize the α3 domain of MICA interfere with the immunosuppressive activity of sMICA on human NK cells and stimulate their activation in an Fc-dependent manner due to the formation of immune complexes with sMICA ( 119 ).…”