Engineering the TGFβ Receptor to Enhance the Therapeutic Potential of Natural Killer Cells as an Immunotherapy for Neuroblastoma

Abstract

Purpose: The ability of natural killer (NK) cells to lyse allogeneic targets, without the need for explicit matching or priming, makes them an attractive platform for cell-based immunotherapy. Umbilical cord blood is a practical source for generating banks of such third-party NK cells for "off-theshelf" cell therapy applications. NK cells are highly cytolytic, and their potent antitumor effects can be rapidly triggered by a lack of HLA expression on interacting target cells, as is the case for a majority of solid tumors, including neuroblastoma. Neuroblastoma is a leading cause of pediatric cancer-related deaths and an ideal candidate for NK-cell therapy. However, the antitumor efficacy of NK cells is limited by immunosuppressive cytokines in the tumor microenvironment, such as TGFb, which impair NK cell function and survival. Experimental Design: To overcome this, we genetically modified NK cells to express variant TGFb receptors, which couple a mutant TGFb dominant-negative receptor to NKspecific activating domains. We hypothesized that with these engineered receptors, inhibitory TGFb signals are effectively converted to activating signals. Results: Modified NK cells exhibited higher cytotoxic activity against neuroblastoma in a TGFb-rich environment in vitro and superior progression-free survival in vivo, as compared with their unmodified controls. Conclusions: Our results support the development of "off-the-shelf" gene-modified NK cells, that overcome TGFb-mediated immune evasion, in patients with neuroblastoma and other TGFb-secreting malignancies.

NK Cell Function Regulation by TGF-β-Induced Epigenetic Mechanisms

“…Genetically modified SMAD3-silenced human NK-92 cells inhibited cancer progression in two xenograft mouse models with human hepatoma and melanoma (56). NK cells genetically modified to express a truncated TGFBR2 receptor fused to the DAP12 activation domain exhibited higher cytotoxic activity against neuroblastoma (57). A deeper knowledge of the mechanisms by which TGF-β acts on NK cells will be useful to improve therapeutic strategies aimed to efficiently restore NK cell activity or to increase the NK cell pool for an effective antitumor response.…”

The immune landscape of neuroblastoma: Challenges and opportunities for novel therapeutic strategies in pediatric oncology

“…TGFb, galectin-1 and MIF are well-known immunosuppressive molecules produced by neuroblastoma, which can impair CTL and/or NK cell function [52,102e106]. In experimental neuroblastoma models, NK cell function was directly modulated by TGFb [107], and tumoural galectin-1 or MIF knockdown resulted in increased T-cell-mediated cytotoxicity, IFNg secretion, CD4 þ and CD8 þ T cell recruitment, and more efficient tumour rejection [104,108,109]. Soluble galectin-1, as well as MIF overexpression, induced T cell apoptosis, inhibited T cell proliferation and inhibited DC maturation [104,110,111].…”

Design and Implementation of NK Cell-Based Immunotherapy to Overcome the Solid Tumor Microenvironment

“…This leads to the conversion of an extracellular inhibitory stimulus to a downstream internal activating signal for cellular activation. Burga et al assessed the anti-tumor activity of feeder cell expanded CB NK cells transduced with a TGF-β receptor II-based switch receptor containing either a DAP12 domain (NKA) or a Notch minimal regulatory region containing a RELA binding domain (SynNotch) [ 63 ]. Both NKA- and SynNotch-transduced NK cells displayed an activation receptor phenotype similar to that of DNRII transduced NK cells and unmodified NK cells.…”