Synthetic promoters to induce immune-effectors into the tumor microenvironment

Abstract

Harnessing the immune-system to eradicate cancer is becoming a reality in recent years. Engineered immune cells, such as chimeric antigen receptor (CAR) T cells, are facing the danger of an overt life-threatening immune response due to the ON-target OFF-tumor cytotoxicity and Cytokine Release Syndrome. We therefore developed synthetic promoters for regulation of gene expression under the control of inflammation and Hypoxia-induced signals that are associated with the tumor microenvironment (TME). We termed this methodology as chimeric-antigen-receptor-tumor-induced-vector (CARTIV). For proof of concept, we studied synthetic promoters based on promoter-responsive elements (PREs) of IFNγ, TNFα and hypoxia; triple PRE-based CARTIV promoter manifested a synergistic activity in cell-lines and potent activation in human primary T-cells. CARTIV platform can improve safety of CAR T-cells or other engineered immune-cells, providing TME-focused activity and opening a therapeutic window for many tumor-associated antigens that are also expressed by non-tumor healthy tissues.

Improving CAR-T immunotherapy: Overcoming the challenges of T cell exhaustion

“… 102 Recently, a synthetic promoter designed to respond to the tumor microenvironment has been shown to efficiently restrict CAR expression to the T cells at the tumor site. 130 The synthetic promoter consists of IFNγ, NFκB, and hypoxia response elements and synergistically activates CAR expression in response to immunosuppressive conditions ( Figure 3 f). In addition to synthetic promoters, endogenous promoters can be appropriated to control the expression of CAR.…”

Implementing Logic Gates for Safer Immunotherapy of Cancer

“…Nonetheless, dividing the specificity task between two promoters, both simultaneously active only in the target cells, could confer the desired precision of action (50)(51)(52). In addition, synthetic promoters comprising distinct transcription factor (TF)-binding elements can assure that transcription of a therapeutic gene takes place only in cells expressing all corresponding TFs (53,54).…”

“…A synthetic promoter [dubbed CARTIV ( 54 )], places a CAR gene under the control of inflammation and hypoxia-induced signals characterizing the TME. To obtain a proof of concept, the authors incorporated into these promoters DNA elements responsive to IFNγ, TNFα and hypoxia and showed an additive effect on CAR expression and function in primary human T cells in the presence of the three stimuli.…”

High throughput screen for the improvement of inducible promoters for tumor microenvironment cues

“…We recently published a novel approach to regulate effector immune cells using promoters that are inducible by the tumor microenvironment (TME) 10 . CARTIVs are built by combining binding sites that respond to factors present within the TME.…”

“…CARTIVs are built by combining binding sites that respond to factors present within the TME. Since tumor microenvironments diverge from normal tissues 11 , we thought to utilize TME factors as inducers for effector immune cells to act against cancerous cells, and spare normal tissues 10 . This is somewhat recapitulating the endogenous immune system control of inducing activity within inflammatory sites in vivo, thus reducing collateral damage to healthy tissues.…”