Engineering NK Cells Modified With an EGFRvIII-specific Chimeric Antigen Receptor to Overexpress CXCR4 Improves Immunotherapy of CXCL12/SDF-1α-secreting Glioblastoma

Abstract

NK cells are promising effector cells for adjuvant immunotherapy of cancer. So far, several preclinical studies have shown the feasibility of gene-engineered NK cells, which upon expression of chimeric antigen receptors (CARs) are redirected to otherwise NK-cell resistant tumors. Yet, we reasoned that the efficiency of an immunotherapy using CAR-modified NK cells critically relies on efficient migration to the tumor site and might be improved by the engraftment of a receptor specific for a chemokine released by the tumor. Based on the DNAX-activation protein 12 (DAP12), a signaling adapter molecule involved in signal transduction of activating NK cell receptors, we constructed an EGFRvIII-CAR, designated MR1.1-DAP12 which confers specific cytotoxicity of NK cell towards EGFRvIII+ glioblastoma cells in vitro and to established subcutaneous U87-MGEGFRvIII tumor xenografts. So far, infusion of NK cells with expression of MR1.1-DAP12 caused a moderate but significantly delayed tumor growth and increased median survival time when compared to NK cells transduced with an ITAM-defective CAR. Notably, the further genetic engineering of these EGFRvIII-specific NK cells with the chemokine receptor CXCR4 conferred a specific chemotaxis to CXCL12/SDF-1α secreting U87-MG glioblastoma cells. Moreover, the administration of such NK cells resulted in complete tumor remission in a number of mice and a significantly increased survival when compared to the treatment of xenografts with NK cells expressing only the EGFRvIII-specific CAR or mock control. We conclude that chemokine receptor engineered NK cells with concomitant expression of a tumor-specific CAR are a promising tool to improve adoptive tumor immunotherapy.

NK cells and cancer: you can teach innate cells new tricks

“…160) and G D2 (REF. 161) showed increased responses to tumour cells in vitro and suppressed tumour growth when tested in vivo in xenograft models 162,163 . Although initially considered as receptors providing 'built-in' ADCC-like NCRL activity against specific tumour antigens, CARs actually elicit a significantly stronger NK cell cytotoxic response than ADCC mediated by anti bodies against the same targets 164 .…”

T-cells “à la CAR-T(e)” – Genetically engineering T-cell response against cancer

“…This was done for example using primary NK cells [337] and the NK92 cell line with the intent of using it as a "off the shelf"/universal donor cell [338,339]. Incorporation of IL15 into the CAR construct increases NK cell persistence in vivo [340], whereas the addition of C-X-X motif chemokine receptor 4 (CXCR4) increased their mobility to the tumor site [341]. Clinical studies evaluating the efficacy of CAR-NK are scarce (half a dozen taking place mainly in China and one in the US [336]) and they mainly target CD19 for B cell malignancies, CD33 for CD33+ AML [147] or MUC1.…”

Chimeric antigen receptor (CAR)-transduced natural killer cells in tumor immunotherapy

“…The PDX model, which is established by transferring of primary tumors directly from the patient into an immunodeficient mouse, can retain the heterogeneity of primary tumor samples and more closely resembles the original clinical cancer than long-established cell lines and standard xenografts; thus, this model has emerged as a powerful tool for studying tumor xenografts [32] . Most CAR-NK cells are transferred to the PDX model to evaluate their safety and efficacy in pre-clinical trials, including CAR-targeting antigens from hematological cancers (eg, CD19, CD20, CD138, and CS-1) [33][34][35][36][37][38] and solid tumors (eg, HER2, EpCam, GD2, GPA7, PSCA, EGFR and EGFRvIII) [14,26,[39][40][41][42][43][44][45][46] (Table 1).…”