From LNP Delivery To Functional CAR-T: Rethinking Targeting

Optimizing lipid nanoparticles (LNPs) for in vivo CAR-T requires a delivery strategy tailored to the biological requirements of the intended T-cell population. Efficient encapsulation, tissue exposure, and cellular uptake do not necessarily translate into productive mRNA delivery or therapeutic activity. Developers must establish whether an LNP reaches the appropriate cells, engages accessible receptors, undergoes internalization and intracellular trafficking, and releases functional mRNA into the cytosol.

A structured optimization framework begins by defining the target population and the required magnitude and duration of CAR expression. Developers can then evaluate active ligand-mediated targeting, formulation-driven biodistribution, or a combination of both. Changes to lipid composition, particle size, PEG-lipid content, and ligand characteristics may influence targeting specificity and downstream delivery, requiring these variables to be assessed together. Performance evaluation must extend beyond CAR expression to include T-cell viability and phenotype, functional activity, off-target expression, immunogenicity, dose response, and repeat-dose performance. Transient CAR expression may be particularly valuable in autoimmune indications where a temporary immune reset is preferred over prolonged B-cell aplasia, allowing the response to be adjusted through dosing.

Ultimately, candidate selection requires balancing biological potency with safety, dosing flexibility, reproducibility, stability, scalability, and process robustness. This integrated approach helps developers identify delivery bottlenecks and select formulations capable of achieving the intended therapeutic response.