A targeted systemic delivery platform of therapeutic modified mRNA and modRNA-derived antibodies for precision triple negative breast cancer treatment.. A targeted systemic delivery platform of therapeutic modified mRNA and modRNA-derived antibodies for precision triple negative breast cancer treatment.

modified mRNA (modRNA) showed high efficacy and safety when used for COVID-19 mRNA vaccines. Upon vaccination, any cell receiving modRNA contributed to efficient expression of antigens resulting in robust immune response. However, in most disease settings it is crucial to restrict translation of therapeutic genes to clinically relevant cells. Here, we designed a breast cancer-Specific modRNA Translation system (bcSMRTs) for enriched gene expression in tumors after systemic delivery with lipid nanoparticles (LNP). Intravenous delivery of bcSMRTs led to a 114-fold increase in tumor-specific signal and a 383-fold decrease in other organs compared to regular modRNA. For therapeutic targeting, we designed modRNA-derived antibodies (modRNabs) in which host cells serve as a bioreactor to produce anti-checkpoint inhibitor antibodies such as anti-cytotoxic T lymphocyte antigen-4 (αCTLA-4). Our results show that αCTLA-4 modRNab inhibited tumor growth by 37% while bcSMRTs carrying Pip4K2c (Phosphatidylinositol-5-phosphate 4-kinase, type II, gamma) gene did so by 25%. Importantly, combining the two reduced tumor size by 75% and reorganized the immune cell landscape in a poorly immunogenic 4T1 model of breast cancer. The modular platform we created to evaluate and screen gene-based treatments in a breast cancer model can easily be adjusted to other types of cancer. Overall design: The 4T1 breast cancer cell line (ATCC, #CRL-2539) was cultured in RPMI (Gibco, #72400-047) supplemented with 10% FBS and pen-strep. Cells were transfected with either Luc or Pip4K2c modRNA using Lipofectamine2000 (Invitrogen, #11668027) and collected 48h post transfection. RNA was isolated using Quick-RNA MiniPrep kit (Zymo Research, #R1055). n=2 in three independent experiments.