CAMBRIDGE, Mass. — Mirai Bio has presented new preclinical data showing that its CD8-targeted lipid nanoparticle platform advanced from initial design to functional proof-of-concept in non-human primates in 10 months.
The Cambridge company, which works with developers of next-generation nucleic acid medicines, presented the data at the 2026 annual meeting of the American Society of Gene and Cell Therapy. The findings support Mirai’s work in targeted delivery systems for in vivo RNA CAR-T programs, including systemic delivery of CAR mRNA to generate CAR-expressing T cells inside the body.
Mirai said the data showed that systemic CAR mRNA delivery generated CAR-expressing T cells in vivo and drove B-cell depletion in non-human primates. The company said its cargo-ready CD8-targeted LNP vehicles could provide partners with a translational foundation for faster and higher-confidence development of in vivo RNA CAR-T programs.
“Nucleic acid medicine programs can only move as fast as their delivery systems allow,” said Jagesh V. Shah, Ph.D., senior vice president and head of platform at Mirai Bio. “These data show that Mirai can help partners move from delivery concept to functional NHP proof-of-concept with the speed and translational relevance needed to make confident development decisions. For in vivo T-cell programs, that means generating the proof points that matter, including functional activity, tolerability, and a clear path toward the clinic.”
T cells are a major target for delivery technologies because of their central role in immune biology and potential relevance across autoimmune diseases, oncology and other immune-mediated conditions. Mirai said its presentations addressed key requirements for in vivo T-cell targeting, including T-cell specificity, reduced liver-directed delivery, scalable production, tolerability and functional activity in relevant models.
In the first poster, Mirai described the discovery and evaluation of novel ionizable lipids and long-circulating LNP compositions designed to support targeted mRNA delivery to T cells outside the liver. The company said it used a modular lipid discovery platform to generate diverse ionizable lipid libraries and screened LNPs with dual mRNA cargoes to assess liver expression and tissue distribution.
Lead particles were reformulated into long-circulating compositions that reduced liver expression and supported extrahepatic delivery in mice. Mirai said those optimized particles were then converted into CD8-targeted LNPs, which showed selective expression in CD8+ T cells, with minimal CD4+ T-cell or B-cell transfection.
When loaded with CD20 CAR mRNA, the CD8-targeted LNPs produced dose-dependent CAR expression and B-cell depletion in CD34+ humanized mice, linking the particle design to functional immune-cell activity, the company said.
In the second poster, Mirai said it expanded the CD8-targeted LNP platform into non-human primate-scale production and in vivo evaluation. The company generated CD8-targeted LNPs carrying mRNA encoding a second-generation anti-CD20 CAR designed to be cross-reactive in humans and cynomolgus monkeys.
After systemic administration in non-human primates, a single dose generated CAR-expressing endogenous CD8+ T cells and rapidly depleted circulating CD20+ B cells for up to seven days after dosing, Mirai said. Reduced CD20+ cells were also observed in the spleen at 72 hours.
Mirai said the studies showed a tolerability profile supportive of continued translational development. Cytokine and clinical chemistry findings were monitored and controlled across the studies, and no major clinical observations were reported in non-human primates through the end of the study.
