Mount Sinai Researchers Develop Cell-Selective mRNA Therapy Platform for Precision Cancer Treatment
Key Insights
Researchers at Mount Sinai (search) developed cSMRTS (search), a first-of-its-kind mRNA (search) system that switches on therapeutic genes preferentially inside targeted cancer (search) cells while sparing healthy tissue.
The platform demonstrated over 100-fold higher gene activity in breast and colon tumors compared to healthy organs, with up to 93% tumor reduction when combined with immunotherapy.
The technology shifts the burden of targeting from delivery vehicles to the mRNA (search) itself, using cancer (search)-specific microRNA (search) patterns to control therapeutic gene activation.
Researchers at the Icahn School of Medicine at Mount Sinai have developed a groundbreaking mRNA (search) system that switches on therapeutic genes preferentially inside targeted cells, demonstrating in mouse studies the potential for safer and more precise cancer (search) treatments. The system, called the cell-selective modRNA translation system (cSMRTS (search)), represents a first-of-its-kind engineered mRNA designed to activate in specific cell populations.
The findings, reported in the November 15 online issue of Molecular Therapy, build on lessons from mRNA (search) COVID-19 vaccines while addressing a critical limitation in current cancer (search) therapies. Unlike vaccines where it doesn't matter which cells produce the protein, treating cancer requires hitting only tumor cells while sparing healthy ones—a level of precision that has been difficult to achieve using current lipid nanoparticle targeting technologies.
Novel Approach to mRNA Targeting
"Our goal was to rethink how mRNA (search) therapies work. Right now, so much effort goes into trying to deliver mRNA to the right place, and even then you get a lot of off-target effects," says first author Magdalena M. Żak, PhD, Instructor in the Cardiovascular Research Institute and the Department of Genetics and Genomic Sciences at Mount Sinai (search). "We wondered whether we could shift the burden from the delivery vehicle to the mRNA itself."
The researchers engineered the mRNA (search) to recognize whether it's inside a cancer (search) cell or a healthy one. If the system senses it's in the wrong environment, it simply shuts off. This built-in decision-making capability distinguishes the technology from current approaches.
Mechanism of Action
The cSMRTS (search) platform acts like a built-in on/off switch that responds to distinct patterns of microRNAs found in cancer (search) cells. MicroRNAs are tiny molecules that help control gene activity, and their patterns differ between cancer and healthy cells.
The system uses two pieces of mRNA (search). One carries instructions for making Cas6 (search), an enzyme that can cut RNA, and includes a spot recognized by cancer (search)-related microRNAs. The other carries the therapeutic gene along with a short RNA loop that Cas6 can recognize and cut.
In cancer (search) cells, cancer-related microRNAs attach to the Cas6 (search) mRNA (search) and shut it down, allowing the therapeutic gene to turn on. In healthy cells, where these microRNAs are missing, Cas6 is produced and cuts the therapeutic mRNA, preventing treatment activation in the wrong cells.
Striking Selectivity Results
When delivered systemically in generic lipid nanoparticles, the platform demonstrated remarkable selectivity in mouse studies testing two cancer (search) models:
- More than 100-fold higher gene activity in breast and colon tumors
- Over 380-fold lower activity in main organs including liver and spleen
- 45% reduction in tumor growth using a tumor-suppressor gene (Pten)
- Up to 93% tumor reduction when combined with mRNA-based immunotherapy
Therapeutic Flexibility and Future Applications
"What's exciting about this system is how flexible it is. Because it's designed to be cell-selective, it's not tied to just one disease or one type of therapy," says senior author Lior Zangi, PhD, Associate Professor of Medicine (Cardiology), and Genetics and Genomic Sciences at Mount Sinai (search). "In principle, this platform could be adapted to many different precision medicines, from cancer (search) to inflammatory and metabolic conditions."
Zangi, who has studied mRNA (search) therapeutics in cardiovascular settings for over 15 years and previously relied on direct intracardiac injections for delivery, expressed particular interest in the technology's potential to safely target specific cells or organs without unwanted gene expression using non-invasive delivery methods.
Expanding mRNA's Therapeutic Reach
Current nanoparticle approaches limit most mRNA (search) therapies to vaccines. By engineering the mRNA payload itself to be selective, the researchers hope cSMRTS (search) introduces a new strategy for reducing toxicity and expanding mRNA's therapeutic applications.
For patients, this could eventually mean access to more targeted, better-tolerated cancer (search) treatments, with long-term potential to adapt the technology to other diseases. The team has filed patent applications and is working toward commercialization and preclinical development.