Objective:

To develop lipid nanoparticles that deliver mRNA to natural killer (NK) cells in vivo and assess their effects in mouse models of cancer and autoimmune hepatitis.

Approach:

• Targeted delivery: Researchers engineered lipid nanoparticles with antibody fragments that target NK-cell receptors, delivering mRNA encoding chimeric antigen receptors (CARs).
• Mouse models: The team tested the platform in models of B-cell lymphoma, T-cell leukemia, melanoma, and autoimmune hepatitis.

Key Findings:

• Nanoparticle delivery efficiency reached approximately 80% in mice. CAR expression peaked around 24 hours and was nearly undetectable by 72 hours.
• In a humanized mouse model of B-cell lymphoma, five doses of CD19 CAR mRNA nanoparticles produced complete remission in all five treated animals, with efficacy comparable to externally manufactured CAR NK cells.
• The platform also showed activity against T-cell leukemia and melanoma.
• In autoimmune hepatitis mice, nanoparticles carrying a CD3-directed CAR and interleukin-15 reduced autoreactive T-cell populations, improved liver enzyme levels, and limited liver damage.
• Repeated dosing was generally well tolerated in mice, but antibodies against the nanoparticle targeting fragments were detected.

Interpretation:

The study reports that mRNA nanoparticles can generate temporary CAR expression in NK cells inside mice and produce antitumor and autoimmune-disease effects in the tested models.

Limitations:

• The reported results are from mouse models; the context provides no human efficacy or safety data.
• CAR expression was short-lived, suggesting repeated dosing may be needed to sustain activity.
• Antibodies against the targeting fragments were detected after repeated administration.

Conclusion:

The researchers describe an in vivo approach to generating CAR NK cells that may avoid the cell collection and laboratory modification required by conventional cell therapies.

Sources:

• Article context provided