In vivo CAR-T cell engineering is gaining increasing attention as a next-generation approach in cell therapy research. By enabling direct genetic programming of T cells inside the body, this strategy aims to address key limitations associated with conventional ex vivo CAR-T manufacturing, including complex logistics, long production timelines, and scalability constraints.
The concept of in vivo CAR-T was established through academic studies demonstrating that lipid nanoparticles (LNPs) can deliver CAR-encoding mRNA selectively to T cells. In landmark peer-reviewed research, targeted LNP systems achieved efficient CAR expression in vivo without the need for ex vivo cell isolation or genetic modification.
These studies provided proof-of-concept that transient mRNA expression could induce functional CAR-T activity while maintaining favorable safety and tolerability profiles in preclinical models.
Building on this academic foundation, Capstan Therapeutics advanced targeted LNP-based in vivo CAR-T toward clinical testing. In June 2025, the company announced the initiation of a Phase I clinical trial of CPTX2309, an anti-CD19 in vivo CAR-T therapy being evaluated for B cell–mediated autoimmune diseases.
Subsequently, a peer-reviewed Science publication reported detailed preclinical validation of Capstan’s targeted LNP (tLNP) platform. The study demonstrated selective delivery of CAR mRNA to CD8⁺ T cells in both humanized mouse and non-human primate models, resulting in effective B cell depletion and observations consistent with immune system reset.
The progress of in vivo CAR-T has drawn significant industry attention. In mid-2025, AbbVie acquired Capstan Therapeutics in an all-cash transaction valued at approximately $2.1 billion. The acquisition underscored growing pharmaceutical interest in targeted mRNA delivery platforms with potential applications across immunology and oncology.
Targeted LNP systems rely on precisely engineered lipid components to achieve stability, biodistribution control, and cell-specific targeting. Functionalized phospholipid–PEG conjugates are widely used to enhance circulation time and enable site-specific attachment of targeting ligands.
Maleimide-functionalized PEG lipids, such as DSPE-PEG-Maleimide, provide a well-characterized chemical handle for conjugating thiol-modified antibodies or peptides, supporting reproducible and controlled ligand presentation on LNP surfaces.
To support mRNA delivery and in vivo CAR-T research, Biopharma PEG supplies a portfolio of functional PEG lipids used in LNP formulation studies, including:
These materials are supplied for research and translational development, with options for GMP-grade production and custom phospholipid–PEG synthesis to support early development and scale-up requirements.
As in vivo CAR-T platforms continue to move from preclinical research toward clinical evaluation, the reproducibility, and quality of delivery system components are expected to play a critical role. Continued advances in targeted mRNA delivery and lipid chemistry will be central to translating this approach into broadly accessible therapies.
About Biopharma PEG
Biopharma PEG is a global supplier of PEG derivatives and functional PEG lipids supporting drug delivery research, mRNA therapeutics, and cell therapy development.
