CRISPR-enhanced engineering of therapy-sensitive cancer cells for self-targeting of primary and metastatic tumors

Abstract

Tumor cells engineered to express therapeutic agents have shown promise to treat cancer. However, their potential to target cell surface receptors specific to the tumor site and their posttreatment fate have not been explored. We created therapeutic tumor cells expressing ligands specific to primary and recurrent tumor sites (receptor self-targeted tumor cells) and extensively characterized two different approaches using (i) therapy-resistant cancer cells, engineered with secretable death receptor-targeting ligands for "off-the-shelf" therapy in primary tumor settings, and (ii) therapy-sensitive cancer cells, which were CRISPR-engineered to knock out therapy-specific cell surface receptors before engineering with receptor self-targeted ligands and reapplied in autologous models of recurrent or metastatic disease. We show that both approaches allow high expression of targeted ligands that induce tumor cell killing and translate into marked survival benefits in mouse models of multiple cancer types. Safe elimination of therapeutic cancer cells after treatment was achieved by co-engineering with a prodrug-converting suicide system, which also allowed for real-time in vivo positron emission tomography imaging of therapeutic tumor cell fate. This study demonstrates self-tumor tropism of engineered cancer cells and their therapeutic potential when engineered with receptor self-targeted molecules, and it establishes a roadmap toward a safe clinical translation for different cancer types in primary, recurrent, and metastatic settings.

Visualizing tumour self-homing with magnetic particle imaging

“…CTCs may represent a novel cell-based platform for therapy whereby, they are highly efficient at homing to established tumour sites, can be readily engineered and expanded ex vivo, and could be generated from an individual patient's tumour to avoid an unwanted immune response. Our group and others have shown exciting progress towards the development of selfhoming CTCs for the treatment of primary and metastatic lesions however, further study is warranted to optimize CTCs for clinical translation [3][4][5][6][7][8][9] . Here, we demonstrate for the first time, the In this work, we visualized iron-labeled MDA-MB-231BR-eGFP cells that had migrated to an MDA-MB-231 primary tumour, which we hypothesized may be due to a well-established tumour microenvironment.…”

“…Due to their tumour targeting capabilities, in recent years, self-homing CTCs have been repurposed as delivery vehicles for anticancer therapeutics. This has included the delivery of oncolytic viruses, pro-drug activatable suicide genes, and transgenes that alter the tumour microenvironment [3][4][5][6][7][8][9] . This strategy has shown exciting progress towards treating primary tumours, single organ metastases and most recently, multi-organ metastases however, further refinement is needed in order to optimize self-homing CTCs for potential clinical translation.…”

“…Cellular imaging can be used to noninvasively study a specific cell population or cellular process in vivo. Previous studies have used imaging reporter genes, namely bioluminescence imaging (BLI) 4,9 and positron emission tomography (PET) reporters 7,8 , to track CTCs in preclinical models.…”

Engineering “self-homing” circulating tumour cells as novel cancer theranostics

“…Therapeutics that have natural tumour tropism or are designed to target lesions offer potential benefits of improved therapeutic effectiveness due to high intratumoural concentration of therapeutic payloads, as well as increased safety due to minimization of off-target cytotoxicity in normal tissues [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][27][28][29][30][31][32]. The incorporation of imaging probes (e.g., radiolabels, iron oxides, etc.)…”

“…In the last two decades, several groups have exploited self-homing CTCs as "self-targeted" delivery vehicles for ex vivo loaded anti-cancer therapeutic cargo [27][28][29][30][31][32]. Cargo has included oncolytic viruses such as the H-1 parvovirus and vesicular stomatitis virus (VSV), prodrug converting enzyme genes including herpes simplex virus thymidine kinase (HSV-TK) and cytosine deaminase (CD), transgenes that target the tumour microenvironment such as tumour necrosis factor (TNF), and the secretory version of TNF-related apoptosis-inducing ligand (S-TRAIL).…”