In recent years, CAR-T cell therapy has achieved groundbreaking advances in hematologic malignancies, offering new treatment options for many patients with refractory diseases. Nevertheless, conventional CAR-T therapies still face industrialization challenges, including lengthy manufacturing cycles, complex production workflows, high costs and limited patient accessibility.
Traditional CAR-T products adopt an ex vivo manufacturing paradigm: T cells are first harvested from the patient, genetically engineered outside the body to express chimeric antigen receptors (CARs), then expanded and subjected to quality testing before being infused back into the patient. Although this highly individualized production enables precise treatment, it also brings complicated manufacturing systems and prolonged waiting periods.
Against this backdrop, in vivo CAR-T technology has attracted growing attention. Its core concept is to bypass the step of extracting the patient’s T cells for ex vivo modification. Instead, delivery systems directly transfer CAR-encoding genetic payloads to T cells inside the patient’s body, reprogramming these cells in situ.
If this technology succeeds, it is expected to break the current reliance of CAR-T therapy on patient-specific manufacturing, bringing it closer to the administration model of conventional pharmaceuticals. However, the advancement of in vivo CAR-T depends not merely on CAR structural design. More critically, it requires safe and efficient delivery of therapeutic genetic information to target cells, with sufficient expression magnitude and duration.
1. Delivery Systems: The Cornerstone of In Vivo CAR-T — Not Only Delivery, but Targeted Delivery
In the development of in vivo CAR-T, delivery technology carries comparable importance to the CAR construct itself.
In conventional gene therapy, a potent therapeutic gene cannot exert its effect if it fails to enter the correct cell type. Accordingly, delivery platforms for in vivo CAR-T must address several core requirements: specific targeting of T cells, efficient release of genetic material, adequate safety profiles, and compatibility with diverse therapeutic payloads.
Lipid nanoparticles (LNPs) are among the most promising delivery platforms. Popularized by mRNA vaccines, LNP technology has far broader applications. Optimizing lipid chemistry and incorporating targeting moieties enables LNPs to deliver various nucleic acid therapeutics, including mRNA, small interfering RNA (siRNA), and gene-editing components.
For in vivo CAR-T, LNPs can deliver mRNA encoding CAR proteins directly into T cells, endowing the patient’s own T cells with new functional capabilities.
Going forward, CAR design and delivery platforms will need to evolve synergistically. More sophisticated and potent CAR architectures demand flexible, high-precision delivery systems. Lagging delivery technology may otherwise become a bottleneck limiting innovation in cell therapy.
Therefore, in vivo CAR-T is not simply an upgraded version of CAR therapy; it represents the integrated advancement of cellular engineering, nucleic acid therapeutics, delivery technology and manufacturing systems.
2. From Customized Manufacturing to Standardized Production: How In Vivo CAR-T May Reshape the Industry Model
Current autologous CAR-T manufacturing requires highly specialized production infrastructure. Starting from patient leukapheresis, the workflow encompasses T cell activation, genetic modification, cellular expansion and final infusion, with stringent controls at every stage.
While this model enables patient-specific treatment, its drawbacks are substantial: long production timelines, high manufacturing costs, complex logistics chains, and risks of disease progression during patient waiting periods.
In vivo CAR-T offers a fundamentally different approach. If delivery systems can generate CAR-T cells directly inside patients, the therapeutic paradigm may shift from “manufacturing a cell batch for each individual patient” to “producing standardized therapeutic products.”
This transformation mirrors the developmental trajectory of other nucleic acid medicines:
- Batch manufacturing can be standardized at the production site;
- Quality control frameworks can be unified;
- Patient treatment workflows may become simpler and faster.
For healthcare systems, this could substantially reduce technical and resource barriers to cell therapy deployment, expanding access to treatment for more patients.
It should be noted that in vivo CAR-T is not a straightforward replacement for existing CAR-T manufacturing workflows; rather, it establishes an entirely new therapeutic modality. Its success hinges on multiple factors, including delivery efficiency, safety, therapeutic durability and clinical efficacy.
3. mRNA Is Only the Starting Point: Evolving Delivery Technologies to Broaden Gene Therapy Applications
Current in vivo CAR-T research predominantly uses mRNA as the genetic carrier, owing to mRNA’s rapid protein expression and favorable controllability.
However, mRNA has a notable limitation: transient expression.
Short-duration protein expression may suffice for certain conditions; for instance, temporary cellular reprogramming can meet the needs of some immune-modulating disorders. For oncology, especially scenarios requiring long-term eradication of tumor cells, the persistence of CAR expression becomes a decisive factor.
Future development of in vivo CAR-T will therefore extend beyond mRNA delivery toward genetic modulation strategies with longer-lasting effects. Examples include gene insertion technologies, transposon systems, gene editing tools and advanced nucleic acid delivery platforms. These technologies may confer stable, even permanent, therapeutic functions to cells.
Meanwhile, the application scope of delivery systems such as LNPs continues to expand. In the future, they may not only reprogram immune cells but also support: in vivo production of therapeutic proteins using the patient’s endogenous cells; tissue-specific genetic modulation; treatment of inherited and metabolic diseases.
The advancement of in vivo CAR-T thus reflects a broader trend: future medicine will increasingly deliver genetic information to directly program cells within the human body to execute therapeutic tasks.
4. Clinical Translation of In Vivo CAR-T Remains Hindered by Challenges in Durability, Safety and Targeted Delivery
Despite immense potential, in vivo CAR-T is not ready for widespread clinical adoption, with several unresolved hurdles. One central challenge is the durability of therapeutic effects.
For cancer treatment, transient T cell activation may be insufficient to sustain long-term anti-tumor activity. Technological advances are needed to prolong CAR expression or achieve stable genetic modification of cells.
Precision delivery represents another critical challenge.
An ideal delivery system should: preferentially target T cells; avoid off-target modification of other cell types; maintain a favorable safety profile; enable controllable dosing and expression levels.
Modification of unintended cell populations may introduce potential risks.
Three core challenges must be addressed for in vivo CAR-T: first, improving delivery precision to direct genetic payloads to the correct cell population; second, extending expression persistence to stabilize therapeutic outcomes; third, establishing standardized manufacturing and quality control systems to enable large-scale deployment.
Over the coming years, continuous progress in delivery technology, gene editing and cellular engineering may propel in vivo CAR-T from proof-of-concept studies toward a mature therapeutic platform.
5. Conclusion: In Vivo CAR-T Is More Than a CAR Technology Upgrade — It Is a Restructuring of Cell Therapy Paradigms
In vivo CAR-T marks an important direction in cell therapy research. Its significance lies not merely in developing more advanced CAR constructs, but in transforming the manufacturing logic of cell therapy.
A successful in vivo CAR-T platform of the future will deliver: enhanced precision in cellular delivery; stable therapeutic expression; streamlined production workflows; and broader patient accessibility.
In the long run, the evolution of in vivo CAR-T will integrate cellular engineering, nucleic acid therapeutics, nanoscale delivery and intelligent manufacturing.
The future of cell therapy may no longer be confined to “manufacturing cells in factories and administering them to patients.” Instead, advanced delivery systems will directly remodel cellular function inside the human body.
The true catalyst for breakthroughs in this field will not be solely the creation of more potent CAR molecules, but the establishment of a next-generation therapeutic system that safely, precisely and sustainably controls cell fate.
