The field of cell therapy is evolving rapidly, and "in vivo" CAR-T is emerging as a major breakthrough. Traditional "ex vivo" CAR-T methods, in which immune cells are extracted, engineered in a lab, and reinfused, have transformed oncology, but it remains costly and operationally complex. In vivo CAR-T eliminates these hurdles by engineering immune cells directly inside the patient’s body, simplifying processes, reducing costs, and potentially improving patient outcomes by eliminating lengthy preparation times.
This shift has gained significant traction. The number of companies developing in vivo CAR-T therapies has nearly tripled since 2023, supported by substantial investments, promising clinical data, and advancements in biotechnology. A key driver of this innovation is progress in nonviral delivery methods, particularly Lipid Nanoparticles (LNPs). LNP-based approaches leverage mRNA technology to enable "transient" gene expression, making them well-suited for autoimmune diseases where temporary immune adjustments are critical. Meanwhile, viral vectors, with which to integrate permanently, are likely to remain central in oncology, where long-term immune surveillance is essential to prevent recurrence and achieve durable responses.
Emerging clinical advancements are further validating the potential of in vivo engineering. Early trials indicate that in vivo CAR-T cells can expand within the body without the need for lymphodepletion or chemotherapy, a significant improvement for current CAR-T therapies. Additionally, these trials demonstrate effective B-cell depletion, a crucial marker of therapeutic success across both oncology and autoimmune indications. If these trends continue, in vivo CAR-T could eliminate the intensive preconditioning regimens currently associated with cell therapies.
Challenges still remain, however. Some programs have reported high-grade Cytokine Release Syndrome (CRS), mirroring safety concerns seen with first-generation ex vivo therapies. Innovations in delivery mechanisms and precise dosing may help mitigate these risks, offering hope for safer, more reliable treatments.
Confidence in the potential of in vivo CAR-T is growing. In 2025, several pharmaceutical giants made multi-billion-dollar acquisitions in the in vivo CAR-T space, underscoring the belief in its long-term potential. Because these therapies are scalable, they can eventually function as "off-the-shelf" solutions, enabling use in community settings rather than specialized centers, a key limitation of current CAR-T.
In vivo CAR-T is poised to disrupt the current cell therapy landscape by eliminating the need for complex manufacturing and supply chains, making treatments more accessible. Beyond cancer, this technology holds significant promise for the $75 billion autoimmune disease market, which dwarfs the global oncology market. The ability to address multiple diseases with customized approaches could further boost adoption potential, reshaping how we think about genetic medicine.
As clinical trials progress in 2026, investors and industry leaders should closely watch how in vivo CAR-T therapies perform compared to existing standards of care. The companies that overcome challenges in manufacturability, scalability, and safety are set to lead the next era of genetic medicine, redefining the possibilities of precision treatment for both cancer and autoimmune diseases.
For more information on related investment opportunities and insights, read CELLect Horizons—Back to the Future: Revisiting the In Vivo CAR-T Landscape, by William Blair biotech analyst Sami Corwin, Ph.D.