Targeted Nanoparticle Technology Eliminates CAR-T Ex Vivo Manufacturing Bottlenecks

Chimeric antigen receptor (CAR) T-cell therapy has significantly transformed the treatment landscape for B-cell malignancies. However, its broader application remains hindered by complex manufacturing processes and the requirement for lymphodepletion chemotherapy, which limit patient accessibility.

In June 2025, a research team led by Haig Aghajanian at the University of Pennsylvania published a paper titled "In vivo CAR T cell generation to treat cancer and autoimmune disease" in Science. The study proposes an in vivo engineering strategy that utilizes targeted lipid nanoparticles (tLNPs) to deliver messenger RNA (mRNA) to specific T-cell subsets.

These tLNPs successfully reprogrammed CD8+ T cells in samples from both healthy donors and patients with autoimmune diseases. Furthermore, in vivo administration achieved tumor control in humanized mice and B-cell depletion in cynomolgus monkeys. In the monkey models, the B cells that returned after depletion were primarily in a naïve state, suggesting an "immune reset". By eliminating the need for complex ex vivo manufacturing, this tLNP platform has the potential to make CAR T-cell therapy more accessible and applicable to a broader range of clinical indications.

Currently, six FDA-approved CAR T-cell therapies are available in the U.S. market for various B-cell malignancies, and hundreds of other autologous and allogeneic CAR-T and CAR natural killer (NK) products are undergoing clinical trials worldwide. While these ex vivo cell therapies have proven highly effective in providing durable outcomes for patients with advanced and refractory cancers, their reach is restricted. Key limitations include manufacturing challenges (cost, time, and scalability), geographic barriers, a limited number of specialized CAR-T centers, the necessity of lymphodepletion chemotherapy, and safety concerns regarding the genotoxicity of integrating viral vectors.

Recently, CAR T-cell therapy has shown immense potential in treating patients with B-cell-mediated autoimmune diseases. New case reports indicate that B-cell-targeted CAR-T therapies can provide significant and lasting clinical benefits for conditions such as systemic lupus erythematosus, myositis, systemic sclerosis, and myasthenia gravis. The population affected by these autoimmune diseases is far larger than that of B-cell malignancies. In the United States, approximately 20 million people suffer from such autoimmune conditions, and globally, the prevalence reaches up to 10%-a figure that continues to rise.

Figure 1. The ionizable lipid L829 can reduce the non-targeted delivery of tLNP to the liver. (Hunter T L, et al., 2025)

Addressing such a massive patient population requires a therapy that is scalable, off-the-shelf, cell-free, and devoid of integrating viral vectors. It must also eliminate the need for chemotherapy pre-conditioning and be administrable at non-specialized medical centers. An in vivo CAR-T approach that bypasses lymphodepletion could meet these requirements. Consequently, this study developed a novel targeted lipid nanoparticle capable of safely and selectively engineering human T cells into functional CAR-T cells directly within the body. The research also established a clinically applicable two-to-three-dose regimen to safely achieve deep B-cell depletion.

Specifically, the study reports a gene delivery system that generates in vivo CAR-T cells by injecting CD8-targeted lipid nanoparticles carrying anti-CD19 CAR mRNA. Data from rodent and non-human primate (NHP) models demonstrate the ability to control tumors. In autoimmune models, a deep and transient reduction of B cells was observed in the blood and tissues of NHPs, leading to an "immune reset". This strategy may offer an off-the-shelf, non-viral, and scalable alternative to traditional ex vivo CAR T-cell immunotherapies.

Reference

Hunter T L, et al. In vivo CAR T cell generation to treat cancer and autoimmune disease. Science, 2025, 388(6753): 1311-1317.