Enhanced CAR-T Therapy for T-Cell Malignancies: The Advantage of Naturally Selected Anti-CD7 Approach

To address the issue of CAR-T cell self-attack, the study presents a novel method for developing anti-CD7 CAR T cells without altering the CD7 gene. The research involves transducing 7CAR into regular T cells, allowing the emergence of CAR-T cells through a natural selection process. The study examines the properties and therapeutic potential of these naturally selected anti-CD7 CAR (NS7CAR) T cells for treating T-cell malignancies.

The method involves measuring CD3+CD7- T cell percentages in blood samples from healthy individuals and patients using flow cytometry. Bulk T cells were selected using magnetic beads, and CD7- T cells were isolated to prevent contamination from malignant cells. The 7CAR gene was inserted into a lentiviral vector and transduced into bulk T cells, resulting in NS7CAR. A comparison was made between NS7CAR, Neg7CAR (7CAR transduced into purified CD7-negative T cells), and KO7CAR (CD7 gene ablation using Cas9 RNP).

The study found that CD7- T cells were present in all age groups of healthy donors and were significantly increased in patients with T-cell acute lymphoblastic leukemia. After 7CAR transduction, a rapid phenotypic change was observed in bulk T cells. Despite fratricide leading to reduced expansion and viability, a substantial number of 7CAR T cells remained viable. After culturing, 7CAR T cells from patients showed enhanced expansion and a larger CD8+ subset compared to those from healthy donors.

NS7CAR T cells demonstrated a lower expansion rate but a higher CAR+ cell percentage, a larger CD8+ subset, and an increased central memory phenotype. Notably, NS7CAR was the only product that showed CD7 mRNA and total protein expression. NS7CAR also exhibited superior cytotoxicity and cytokine release in vitro and provided robust protection against leukemia progression in an animal model.

The study concludes that NS7CAR T cells are enriched in CAR+ cells and contain a higher percentage of CD8+ central memory T cells. Patient-derived PBMCs were found to be more effective in producing NS7CAR T cells for therapy compared to those from healthy donors. An ongoing trial is assessing the feasibility, efficacy, and safety of NS7CAR T cells for treating T-cell acute lymphoblastic leukemia.