The Science Behind Self-Amplifying RNA
A fundamentally new class of RNA medicine — engineered for systemic delivery, sustained expression, and coordinated immune activation against cancer.
Platform Overview
Self-amplifying RNA (saRNA) is a next-generation RNA modality derived from alphavirus replicon technology. Unlike conventional mRNA, saRNA encodes its own replication machinery, enabling exponential amplification of therapeutic protein expression within target cells from a single low dose.
- Derived from alphavirus replicon technology with a well-characterized safety profile
- Encodes a replicase complex that amplifies RNA copies intracellularly — no viral particles produced
- Designed for IV administration, enabling systemic access to disseminated tumors
- Lipid nanoparticle (LNP) formulation optimized for tumor-preferential delivery
Mechanism of Action
IV Administration & LNP Delivery
Oncorus saRNA is encapsulated in engineered lipid nanoparticles and administered intravenously. LNPs are designed to preferentially accumulate in tumor tissue through the enhanced permeability and retention (EPR) effect and active targeting.
Cellular Uptake & Endosomal Escape
LNPs are internalized by tumor cells and antigen-presenting cells. Optimized lipid composition facilitates endosomal escape, releasing saRNA into the cytoplasm where it engages the cellular translation machinery.
Self-Amplification & Sustained Expression
The saRNA replicase complex amplifies RNA copies within the cell, producing high-level, sustained therapeutic protein expression over days to weeks — from a fraction of the dose required by conventional mRNA.
Tumor Cell Killing & Immune Activation
Expressed therapeutic payloads directly kill tumor cells while simultaneously activating innate and adaptive immune pathways — engaging T cells, NK cells, and cytokine cascades to mount a durable anti-tumor response.
saRNA vs. Conventional mRNA
Self-amplifying RNA addresses the fundamental limitations of conventional mRNA therapeutics in oncology.
| Attribute | saRNA (Oncorus) | Conventional mRNA |
|---|---|---|
| Dose required | Low — replicase amplifies intracellularly | High — no amplification, rapid degradation |
| Duration of expression | Days to weeks of sustained expression | Hours to days, rapidly cleared |
| Immune activation | Innate + adaptive arms engaged simultaneously | Primarily adaptive; innate activation limited |
| Delivery route | IV — systemic, reaches disseminated disease | Typically local injection; systemic delivery challenging |
| Payload capacity | Large — accommodates complex therapeutic constructs | Limited by translation efficiency at scale |
Key Advantages
Systemic Reach
IV administration enables access to metastatic and disseminated tumors that localized injection-based approaches cannot address — a critical requirement for most solid tumor indications.
Dose Efficiency
Intracellular self-amplification produces therapeutic protein levels from a fraction of the RNA dose required by conventional mRNA, reducing manufacturing burden and potential off-target exposure.
Multi-Arm Immunity
saRNA replication triggers innate immune sensing pathways (RIG-I, MDA5) while therapeutic payloads activate adaptive immunity — creating a coordinated, multi-front anti-tumor response.
Flexible Payload Design
The saRNA platform accommodates diverse therapeutic payloads — cytokines, tumor antigens, checkpoint modulators — enabling rapid iteration across oncology indications.
Selected Publications
Oncorus's scientific foundation is supported by peer-reviewed research in RNA biology, LNP delivery, and cancer immunology.
Self-amplifying RNA vaccines give equivalent protection against influenza to mRNA vaccines but at much lower doses
Geall AJ, et al.
Lipid nanoparticle technology for clinical translation of siRNA therapeutics
Kulkarni JA, et al.
Innate immune sensing of cytosolic chromatin fragments through cGAS promotes senescence
Glück S, et al.
Alphavirus replicon particles as candidate HIV vaccines
Pushko P, et al.