# Triplet RNA Lipid Nanoparticles for Locoregional Cancer Immunotherapy

## TL;DR

This study explores using lipid nanoparticles to deliver RNA-based therapies that stimulate the immune system to fight cancer.

## Contribution

A new 'triplet RNA' approach is proposed, combining immunostimulatory RNA, mRNA, and siRNA in a single nanoparticle platform for cancer immunotherapy.

## Key findings

- pIpC-LNPs administered intratumorally caused complete remission in 25% of tumors.
- Combining pIpC-LNPs with siPDL1 reduced tumor growth.
- OX40 and CD27 are strongly upregulated following pIpC-LNP treatment.

## Abstract

Ionizable lipid nanoparticles (LNPs) are a proven means of delivering nucleic acid‐based therapeutics. This project aims to expand the LNP platform for the delivery of immunostimulatory polyinosinic‐polycytidylic acid (pIpC). It is demonstrated that pIpC could be successfully incorporated into LNPs with minimal modification to existing protocols. LNPs encapsulating pIpC (pIpC‐LNPs) exhibit a spherical shape with a diameter under 200 nm. When administered intratumorally, pIpC‐LNPs are significantly more potent than the soluble adjuvant, resulting in complete remission in 25% of tumors. To identify potential synergistic targets, T cell activation markers are screened following pIpC‐LNP treatment. OX40 and CD27 are strongly upregulated and associated with intratumoral pIpC‐LNP administration. Furthermore, direct treatment of a cancer cell line with pIpC‐LNPs results in upregulation of the immunosuppressive PDL1. To develop a comprehensive RNA‐based immunotherapeutic strategy, LNPs are formulated with mRNAs encoding CD70 (the CD27 ligand) and OX40L, or with siRNA targeting PDL1, and are evaluated in combination. Tumor growth reduction is observed when pIpC‐LNPs are combined with siPDL1. This study demonstrates the potential of a triplet RNA platform‐comprising immunostimulatory RNA, mRNA, and siRNA, delivered via a single versatile LNP. The data support development of pIpC‐LNPs as potent intratumoral therapeutics and highlight several potential synergistic targets.

LNPs deliver the immunoadjuvant pIpC into tumors to activate local cells. After activation, additional RNA (siRNA or mRNA) can modulate immune pathways by suppressing immunoinhibitory targets or inducing immunostimulatory ones. This coordinated “triplet RNA” approach may enhance immune activation within the tumor microenvironment.© 2026 WILEY‐VCH GmbH