Using A Novel Viral Vector Platform to More Efficiently Manufacture CAR-T Cells

In a new study, Associate Professor Leszek Liowski and his team at the University of Sydney have identified a new method for producing a therapeutic product, chimeric antigen receptor (CAR) T cells, which has the potential to improve the treatment of cancer. The relevant research results were recently published in the journal Molecular Therapy, with the title of the paper "Tailoring capsid-directed evolution technology for improved AAV-mediated CAR-T generation".

CAR-T cells are a relatively new form of treatment that has shown very exciting results in the treatment of several types of cancer. Although the technology was initially proven to be useful for treating B-cell malignancies, especially acute lymphoblastic leukemia (ALL), it has also shown promise for other cancer types, including solid tumors. In most cases, CAR-T cells are made by genetically modifying a patient's own T cells to produce specially designed CARs that enable them to seek out and kill cancer cells. To convert T cells into CAR-T cells, scientists usually modify the patient's T cells using a viral vector that encodes the CAR components.

Currently, the U.S. Food and Drug Administration (FDA) has approved six CAR-T cell products, all of which use viral vectors as a delivery system. To improve CAR-T cell products, people are studying how viral vectors affect CAR-T cells, especially their specificity and long-term efficacy.

In recent years, advances in CAR-T cell technology include the use of new viral vectors to deliver functional CARs to patients' T cells to produce therapeutic CAR-T cell products. Based on intrinsic safety, AAV vectors, which are most commonly used to deliver therapeutic genes directly to patients, are the next frontier for CAR-T cell products. In this study, Associate Professor Liowski and his team, including co-author Adrian Westhaus, developed a new method to construct new customized AAV variants that can more effectively target patients' T cells.

Figure 1. Side-by-side comparison of homology-directed repair performance of novel AAV capsids in T cells. (Westhaus A, et al., 2024)

In this proof-of-concept study, the Liowski team found that this significantly reduced viral vector dose could not only reduce the cost of future CAR-T cell products. But more importantly, the team was also able to confirm that therapeutic CAR-T cells developed using these new AAVs killed cancer cells with greater efficiency, which could also potentially improve the therapeutic efficacy of new therapies.

"To achieve this goal, we studied how AAV vectors affect the speed of gene editing and used this knowledge to develop a new AAV selection method," said Associate Professor Liowski. "This allowed us to quickly bioengineer new AAVs for gene editing applications. This is a strategy for permanently modifying T cells to make CAR-T cells."

Following this selection process, the researchers functionally validated the selected viral vectors. The two best-performing candidate viral vectors (AAV-T1 and AAV-T2) generated CAR-T cells more efficiently and produced more functionally active CAR-T cells than AAV6, the AAV currently used in CAR-T cell development.