Bispecific antibody-mediated redirection of NKG2D-CAR natural killer cells facilitates dual targeting and enhances antitumor activity

Abstract

BackgroundNatural killer group 2D (NKG2D) is an activating receptor of natural killer (NK) cells and other lymphocytes that mediates lysis of malignant cells through recognition of stress-induced ligands such as MICA and MICB. Such ligands are broadly expressed by cancer cells of various origins and serve as targets for adoptive immunotherapy with effector cells endogenously expressing NKG2D or carrying an NKG2D-based chimeric antigen receptor (CAR). However, shedding or downregulation of NKG2D ligands (NKG2DL) can prevent NKG2D activation, resulting in escape of cancer cells from NKG2D-dependent immune surveillance.MethodsTo enable tumor-specific targeting of NKG2D-expressing effector cells independent of membrane-anchored NKG2DLs, we generated a homodimeric recombinant antibody which harbors an N-terminal single-chain fragment variable (scFv) antibody domain for binding to NKG2D, linked via a human IgG4 Fc region to a second C-terminal scFv antibody domain for recognition of the tumor-associated antigen ErbB2 (HER2). The ability of this molecule, termed NKAB-ErbB2, to redirect NKG2D-expressing effector cells to ErbB2-positive tumor cells of different origins was investigated using peripheral blood mononuclear cells, ex vivo expanded NK cells, and NK and T cells engineered with an NKG2D-based chimeric receptor.ResultsOn its own, bispecific NKAB-ErbB2 increased lysis of ErbB2-positive breast carcinoma cells by peripheral blood-derived NK cells endogenously expressing NKG2D more effectively than an ErbB2-specific IgG1 mini-antibody able to induce antibody-dependent cell-mediated cytotoxicity via activation of CD16. Furthermore, NKAB-ErbB2 synergized with NK-92 cells or primary T cells engineered to express an NKG2D-CD3ζ chimeric antigen receptor (NKAR), leading to targeted cell killing and greatly enhanced antitumor activity, which remained unaffected by soluble MICA known as an inhibitor of NKG2D-mediated natural cytotoxicity. In an immunocompetent mouse glioblastoma model mimicking low or absent NKG2DL expression, the combination of NKAR-NK-92 cells and NKAB-ErbB2 effectively suppressed outgrowth of ErbB2-positive tumors, resulting in treatment-induced endogenous antitumor immunity and cures in the majority of animals.ConclusionsOur results demonstrate that combining an NKAB antibody with effector cells expressing an activating NKAR receptor represents a powerful and versatile approach to simultaneously enhance tumor antigen-specific as well as NKG2D-CAR and natural NKG2D-mediated cytotoxicity, which may be particularly useful to target tumors with heterogeneous target antigen expression.

Comprehensive analysis to identify long non-coding RNA HCP5/MICA axis as a prognostic biomarker in glioblastoma

“…MICA seemed to have immune-mediated antitumor function via the above pathway in GBM, while it displayed the opposite function in colorectal cancer and prostate cancer [28,29]. Besides, soluble MICA can also inhibit the natural killer cell killing activity in breast carcinoma cells and increase hepatitis C virus-related hepatocellular carcinoma risk [25,30]. The dual functions of MICA in different cancers indicates that it involves in multiple pathways.…”

Tumor buster - where will the CAR-T cell therapy ‘missile’ go?

“…Preclinical trials of ganglioside 2 (GD2), protein tyrosine kinase 7 (PTK7), and NKG2DL as CAR-T cell therapy targets also showed anti-BC activity [177,[193][194][195] (Fig. 3).…”

Immune surveillance in glioblastoma: Role of the NKG2D system and novel cell‐based therapeutic approaches

“…Furthermore, this construct greatly enhances antitumour activity of NK-92/5.28.z and NKG2D CAR T cells engineered to express an NKG2D-CD3ζ chimeric antigen receptor, which remains unaffected by soluble MICA. 185 While the MAb therapy is promising for many extracranial malignancies, their use for targeting brain cancers may be challenging, particularly due to the presence of the BBB preventing easy access of antibodies to the brain parenchyma. However, different antibody-delivery platforms are in preclinical development that may help to deliver antibodies at the tumour site across the BBB.…”

“…For instance, the bispecific anti‐NKG2D‐HER2 construct sensitizes NK cells towards HER2‐positive breast carcinoma cells. Furthermore, this construct greatly enhances anti‐tumour activity of NK‐92/5.28.z and NKG2D CAR T cells engineered to express an NKG2D‐CD3ζ chimeric antigen receptor, which remains unaffected by soluble MICA 185 . While the MAb therapy is promising for many extracranial malignancies, their use for targeting brain cancers may be challenging, particularly due to the presence of the BBB preventing easy access of antibodies to the brain parenchyma 186,187 .…”