CAR T-Cell Therapy Has a Manufacturing Problem. In Vivo Is the Fix.
CAR T-cell therapy has revolutionized treatment for some blood cancers, giving new hope to patients when standard therapies are not working. But there is a major problem behind these impressive results: time. Traditional CAR T-cell therapy requires a patient’s T cells to be collected, genetically engineered, multiplied in a laboratory, tested, and infused back into the patient—a process that can take 3–6 weeks. For patients with aggressive cancers, that wait can be too long. This is where in vivo CAR T-cell therapy could change the equation. Instead of sending cells to a laboratory, this approach engineers a patient’s T cells directly inside the body. This could potentially bypass much of the traditional manufacturing process. The global CAR T-cell therapy market was valued at USD 5.59 billion in 2025. The market is projected to reach USD 19.15 billion by 2034, positioning in vivo CAR T as a potential major catalyst for the market’s next phase of growth.
What Is In Vivo CAR T-Cell Therapy? A Plain-Language Explanation
The main difference in in vivo vs ex vivo CAR T is simple: where are the T cells changed? In the traditional approach, they are changed outside the body in a laboratory. With in vivo CAR T, the goal is to change them directly inside the patient.
The Traditional (Ex Vivo) Method
In conventional CAR T therapy, T cells are collected through leukapheresis, genetically engineered and expanded in a laboratory, then infused back into the patient following lymphodepletion chemotherapy. The complete vein-to-vein process can take 4–8 weeks. This complex manufacturing process also leads to a high cost of CAR T manufacturing, which can be up to hundreds of thousands of dollars per patient.
The In Vivo Approach
In vivo CAR T takes a different approach. Delivery vehicles carry CAR instructions to T cells inside the body. The cells are then changed directly inside the patient. This could reduce the need for cell collection and lab expansion. It could also make treatment faster and simpler. This is why in vivo CAR T is being explored as a next-generation CAR T therapy in 2026.
Ex Vivo vs. In Vivo CAR T-Cell Therapy
| Feature | Ex Vivo CAR T | In Vivo CAR T |
| Where cells are changed | In a lab | Inside the body |
| Cell collection | Required | Potentially not required |
| Cell expansion | Required | Not required |
| Treatment timeline | Several weeks | Potentially much shorter |
| Manufacturing | Complex | Potentially simpler |
How In Vivo CAR T Works: Two Leading Delivery Platforms
For in vivo CAR T-cell therapy to work, CAR instructions must reach the right T cells. Two approaches are leading this field: lentiviral vectors and lipid nanoparticles (LNPs). These technologies are also key to understanding in vivo vs ex vivo CAR T.
1. Lentiviral Vectors
Lentiviral vectors are modified viruses. They carry CAR genes into T cells. The genes then become part of the cell’s DNA. This is one of the more advanced approaches being studied. Kelonia Therapeutics is developing KLN-1010 for in vivo CAR T treatment. Early clinical data have shown CAR T-cell activity without traditional lymphodepletion. Source: https://www.biospace.com
2. Lipid Nanoparticles (LNPs)
LNPs are tiny fat-based particles. They carry genetic instructions, such as mRNA, into T cells. They can avoid permanent changes to cell DNA. Repeat dosing may also be possible. Companies such as Sail Biomedicines and Mirai Bio are using AI to improve LNP design and T-cell targeting.
Why In Vivo CAR T Could Unlock a USD 19 Billion Market Opportunity
The growth of in vivo CAR T-cell therapy could change more than how CAR T is made. It could also expand who can access it and what diseases it can treat.
1. Lower Treatment Costs
Ex vivo manufacturing is a major part of the CAR T manufacturing cost. Simplified lab steps could reduce cost per patient. If costs are reduced sufficiently, more patients may qualify for treatment.
2. Wider Patient Access
In vivo CAR T may reduce the need for specialised manufacturing facilities. This could help more hospitals offer treatment. It could also improve access in markets such as India and Southeast Asia.
3. More Treatment Options
In vivo platforms may allow repeat dosing and easier changes to CAR designs. This could create new opportunities in autoimmune and other chronic diseases.
These changes together could support next gen CAR T therapy in 2026 and boost long-term growth of the market.
In Vivo CAR T Is Not Without Challenges
In vivo CAR T-cell therapy has strong potential, but several questions remain.
Off-Target Risk
Delivery vehicles may reach cells other than T cells. This could create safety concerns. Researchers are working to improve cell targeting.
Durability Questions
Some LNP approaches use mRNA. Its effects are temporary. More data are needed to understand how long CAR T cells can remain active.
Immune Rejection
The immune system may attack the delivery vehicle. This could make repeat dosing more difficult.
Regulatory Uncertainty
In vivo CAR T is still an emerging field. No in vivo CAR T product has received FDA or EMA approval yet. More clinical and safety data are needed before these therapies can become widely available.
Frequently Asked Questions About In Vivo CAR T-Cell Therapy
What is the difference between in vivo and ex vivo CAR T-cell therapy?
Ex vivo CAR T modifies T cells outside the body before they are returned to the patient. In vivo CAR T modifies T cells directly inside the body.
Has in vivo CAR T-cell therapy been approved by the FDA?
No, no in vivo CAR T therapy has received FDA approval as of 2026. Several clinical trials are currently evaluating these treatments.
How does in vivo CAR T reduce cost?
It could reduce the need for cell collection, lab processing and cell expansion. This could reduce the cost of manufacturing CAR T and improve access to treatment.
The In Vivo Revolution Is Just Beginning
The shift from ex vivo to in vivo CAR T could become one of the biggest changes in the CAR T market through 2034. By making treatment simpler and potentially more accessible, in vivo CAR T could open new opportunities for patients, providers, and developers.
