CRISPR Revolutionizes CAR T Cell Production In Vivo

A groundbreaking study published on March 24, 2026, highlights the efficacy of creating CAR T cells in vivo through an innovative use of CRISPR technology. Researchers discovered that these cells exhibited improved characteristics and better performance compared to traditional in vitro engineered cells.

CAR T Therapies: Promising but Imperfect

T cells, also known as killer cells, are integral to our adaptive immune systems due to their ability to eradicate cancerous cells. However, they frequently fail to identify tumor cells as threats or are inhibited by the tumor microenvironment ^[2].

CAR T cell therapy addresses these challenges by genetically modifying T cells to express a chimeric antigen receptor (CAR), which allows them to target specific tumor markers, such as CD19 on leukemia cells. Currently, seven CAR T therapies have received FDA approval and have shown promising results in inducing durable remissions for patients with refractory blood cancers ^[3].

The conventional methodology involves:

• Collecting patient-derived T cells.
• Transporting them to a specialized facility for gene delivery using retroviral or lentiviral vectors.
• Expanding the cells in a controlled environment before re-infusing them into the patient.

This standard procedure can take between 3-5 weeks and incurs costs upwards of hundreds of thousands of dollars. Moreover, patients may not have access to effective treatment in a timely manner.

Who Ordered CRISPR Delivery?

The recent study from the University of California San Francisco marks a significant departure from traditional methodologies by generating CAR T cells in vivo. This novel approach utilizes a CRISPR-based DNA-targeting system along with a DNA repair template to seamlessly integrate CAR genes into the T cell genome at the T cell receptor alpha constant (TRAC) locus ^[4].

The researchers employed two sophisticated delivery mechanisms. Initially, enveloped delivery vehicles (EDVs) carrying the CRISPR cutting complex performed targeted delivery. Concurrently, an adeno-associated virus (AAV) introduced the CAR gene along with sequences that align with the regions adjacent to the CRISPR cut site. This enables the cell's native DNA repair system to incorporate the CAR gene precisely into the genomic location.

After validating their concept in vitro, the team proceeded with an experiment using immunodeficient mice engrafted with human immune cells. An intravenous injection of the EDV + AAV combination containing the CD19-CAR was administered, leading to significant findings two weeks later:

• TRAC-CAR T cells were successfully identified in the spleens of the mice.
• Depletion of CD19-expressing B cells indicated that the CAR T cells were effectively combating their targets.

The experiments confirmed that the TRAC-CAR T cells were functional and displayed a memory-like phenotype ready to respond to antigen re-exposure.

Knocking Out Real Cancers

Continuing their research, the team challenged mice with aggressive leukemia and replicated their therapy using human PBMCs (peripheral blood mononuclear cells). Remarkably, 18 out of 20 mice exhibited complete tumor elimination.

The team also contrasted their novel design against other methodologies currently in clinical trials. The TRAC-CAR T therapy significantly outperformed lentivirus-based CAR T therapies in terms of tumor eradication, with a success rate of 100% in the tested cohorts.

Table 1: Comparison of CAR T Cell Therapies

To further evaluate the versatility of this approach, the team applied their technique to treat multiple myeloma and sarcoma, achieving promising results in both cases, although donor variability posed challenges.

Potential Implications

Translating this innovative therapy to human patients could transform the field of CAR T cell treatment. Dr. Justin Eyquem, the senior author, emphasized that this method could significantly reduce costs, minimize waiting times, and allow broader access to effective treatments across various medical facilities, including smaller community hospitals.

“If we can translate this to humans, we could dramatically reduce costs, eliminate waiting times, and potentially allow community hospitals to offer these life-saving therapies.” – Dr. Justin Eyquem, UCSF

Literature

• Nyberg, W. A., et al. (2026). . Nature, 1-10.
• Chen, D. S., & Mellman, I. (2013). . Immunity, 39(1), 1-10.
• Maude, S. L., et al. (2018). . New England Journal of Medicine, 378(5), 439-448.
• Eyquem, J., et al. (2017). . Nature, 543(7643), 113-117.
• Xu, J., et al. (2025). . The Lancet, 406(10500), 228-231.

About the Author

Arkadi Mazin
Arkadi is a seasoned journalist and op-ed author with a passion for learning and exploration. His interests span from politics to science and philosophy. Having studied economics and international relations, he is particularly interested in the social aspects of longevity and life extension. He strongly believes that life extension is an achievable and noble goal that has yet to take its rightful place on the very top of our civilization’s agenda – a situation he is eager to change.

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