Abstract 1732: Nanoparticle delivery of cancer-activated DNA enables the detection and localization of tumors in mice
Authors: Ananthanarayanan Badri , Nieu Regina , Ji Weihang , McCarthy Blaine , Zhu Shengshuang , Harwig Alex , Louie Maggie C. , Suhy David 
Published: June 2022

The expression of synthetic biomarkers from genetic constructs represents a new paradigm of molecular diagnostic tools for early cancer detection and localization. One of the limitations of liquid biopsy approaches is the low abundance of endogenous biomarkers shed in early-stage disease. To overcome this, Earli’s platform instead uses genetic constructs to force tumors to produce cancer-activated synthetic biomarkers. Thus, technologies that deliver DNA to tumor cells in multiple tissues need to be developed. While non-viral delivery systems such as lipid nanoparticles (LNPs) have achieved clinical success for RNA, the delivery of DNA to tumor cells remains a challenge. We have engineered two classes of nanoparticles using biodegradable and ionizable cationic materials. The efficacy of these nanoparticles to deliver a DNA nanoplasmid containing a cancer-activated promoter to drive expression of a secreted embryonic alkaline phosphatase (SEAP) was evaluated in multiple cell-derived xenograft (CDX) models.

The first class of nanoparticles was comprised of poly-beta-amino-ester polymers (PBAEs). Systematic screening of a library of PBAEs and optimization of PEG-lipid content produced nanoparticles approximately 80-100 nm in diameter with slightly positive zeta potential, enabling biodistribution to mouse lung tissues. Testing of initial nanoparticle compositions identified safe and effective formulations that produced 5-fold higher SEAP expression levels in lung tumor-bearing animals versus naïve mice. Further enhancements produced SEAP levels up to 250-fold higher in tumor-bearing versus control mice but resulted in significant increases in liver enzymes, suggesting tolerability issues that are currently being addressed by improving the polymer and formulation composition.

The second class of nanoparticles was composed of ionizable lipids such as DLin-MC3-DMA that have been clinically validated for RNA delivery to the liver. Optimized compositions with helper lipid and PEG-lipid variants identified formulations that could successfully deliver DNA to the liver. These formulations produced 30-fold higher SEAP expression in tumor-bearing animals compared to naïve controls in an H1299 CDX model. A 7-fold difference in SEAP levels was demonstrated in an orthotopic Hep3B CDX model between tumor versus non-tumor bearing animals. Strikingly, LNP delivery of a cancer-activated Renilla luciferase construct produced tumor-specific bioluminescence, demonstrating the ability of the LNPs to localize liver tumors. LNP formulations were well tolerated, producing transient, mild to moderate elevations in liver enzymes one day after administration that subsequently resolved. These potent and safe nanoparticle delivery systems are promising agents for enabling future clinical translation of our synthetic biomarker platform.

Citation Format: Badri Ananthanarayanan, Regina Nieu, Weihang Ji, Blaine McCarthy, Shengshuang Zhu, Alex Harwig, Maggie C. Louie, David Suhy. Nanoparticle delivery of cancer-activated DNA enables the detection and localization of tumors in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1732.