Advances in In Vivo CAR-T Cell Therapy

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment landscape for patients with hematological malignancies. However, its widespread application remains constrained by labor-intensive manufacturing processes, limited production capacity, and inconsistent clinical efficacy. In vivo CAR-T cell engineering, which generates CAR-T cells directly within the patient's body, eliminates the need for ex vivo cell processing and complex logistics while enhancing clinical outcomes, thereby addressing these challenges.

Recently, CAR-T therapy pioneer Carl June, Nobel laureate and mRNA technology innovator Drew Weissman, along with researchers from cell therapy and mRNA companies such as Capstan, Umoja, Kelonia, Moderna, Myeloid, Interius, Orna, Sana, and Carisma, published a review titled "In vivo chimeric antigen receptor (CAR)-T cell therapy" in Nature Reviews Drug Discovery. The review explores the core technologies of in vivo CAR-T, including lipid nanoparticle (LNP)-mediated RNA delivery and engineered viral vectors, and discusses how technological refinements can develop CAR-T therapies with broader applicability, greater scalability, improved safety, and enhanced efficacy. By eliminating the need for ex vivo manipulation and chemotherapy-based preconditioning, this strategy expands the potential applications of CAR-T therapy beyond hematological cancers to autoimmune diseases such as systemic lupus erythematosus.

In the paper, the authors first examine key insights gained from the development of traditional ex vivo-engineered CAR-T cell products, which have spurred efforts to advance in vivo CAR technology as an alternative approach. This novel strategy removes the constraints of cell manufacturing and associated logistical barriers while avoiding chemotherapy-based lymphodepletion, unlocking CAR technology's full potential for broader indications, including those requiring higher safety standards.

Next, the review summarizes major in vivo CAR platforms and the preclinical or clinical proof-of-concept supporting their development. Finally, it discusses potential limitations, strategies for clinical translation, and how progress in this field may drive broader applications of in vivo immune cell engineering through diverse mechanisms of action and payloads.

The development of ex vivo CAR-T cell products marked a major milestone in medicine but also revealed limitations in accessibility and clinical performance. To overcome these challenges, in vivo CAR technology emerged, benefiting from advancements in virology, RNA therapeutics, and nanomedicine. Currently, two primary in vivo CAR platforms are advancing toward clinical translation: engineered viral (lentiviral or γ-retroviral) vectors that integrate payloads into the host genome, and lipid nanoparticles (LNPs) that enable transient payload expression in host cells.

Figure 1. The main in vivo CAR platforms currently under development and their mechanisms of action. (Bot A, et al., 2025)

Most current efforts focus on optimizing platform and product designs using validated targets, including B-cell lineage antigens (CD19, BCMA, CD20, CD22) with dual applicability in oncology and autoimmunity, as well as solid tumor targets (TROP2, GPC3). Multiple candidates leveraging engineered viruses and LNP-RNA are progressing toward clinical translation. After initial candidates demonstrate safety, tolerability, and clinically meaningful biological activity, they are expected to rapidly advance into proof-of-concept and registration trials, with expanded clinical testing across oncology and autoimmune indications. Given the novelty of these platforms and their yet-to-be-defined therapeutic indices, most candidates will likely first be tested in oncology before expanding to autoimmune or regenerative medicine applications.

As the technology evolves, product concepts, payload architectures, and targeted delivery vectors are expected to diversify, enabling increasingly innovative and disruptive in vivo therapies for diseases traditionally difficult to treat.

Thirty-five years after the first evaluation of in vivo genetic immunization using plasmid DNA, 25 years after the first clinical use of intravenous retroviral vectors, and eight years after the first approved CAR-T cell product, this review envisions a future of precise and sophisticated in vivo immune system programming. These technologies, now entering clinical stages, will ultimately enable spatiotemporal control and tunability of payload expression, as well as multi-mechanistic synergy, surpassing the capabilities of current therapies to enhance clinical outcomes across a broader range of diseases.

More specifically, the conceptual shift from ex vivo to in vivo CAR-T cell therapy redefines the scalability and accessibility of immunotherapy, driven by significantly reduced production costs. This has profound socioeconomic implications, facilitating broader access to life-saving treatments.

Reference

Bot A, et al. In vivo chimeric antigen receptor (CAR)-T cell therapy. Nature Reviews Drug Discovery, 2025: 1-22.