Gene-Edited BE-CAR7 Cells Achieve Deep Remission in Aggressive T-Cell Leukemia

December 8, 2025 — A novel treatment utilizing genome-edited immune cells, developed by scientists at UCL (University College London) and Great Ormond Street Hospital (GOSH), has shown promising long-term results in helping children and adults fight aggressive T-cell acute lymphoblastic leukemia (T-ALL).

The world-first therapy, BE-CAR7, uses base-edited immune cells—an advanced version of CRISPR technology—to treat previously untreatable T-cell leukemia. The results of the clinical trial, involving eight children and two adults treated at GOSH and King’s College Hospital (KCH), were presented at the 67th American Society of Hematology (ASH) Annual Meeting and published in The New England Journal of Medicine.

Key Clinical Findings

The study demonstrated high response rates, allowing patients who had exhausted standard therapies to proceed to curative stem cell transplants:

• Deep Remission: 82% of patients achieved very deep remissions after receiving BE-CAR7, enabling them to undergo a subsequent stem cell transplant without detectable disease.

• Disease-Free Survival: 64% of patients currently remain disease-free, with the first patients now three years disease-free and off treatment.

• Safety: Anticipated side effects, including low blood counts and cytokine release syndrome, were deemed tolerable.

“We’ve shown that universal or ‘off the shelf’ base-edited CAR T-cells can seek and destroy very resistant cases of CD7+ leukemia,” said Professor Waseem Qasim, who led the research at UCL and GOSH.

New Technology: Base Editing for Universal CAR T-Cells

Developing traditional CAR T-cell therapy for T-ALL is uniquely challenging because the engineered T-cells can attack the therapy itself (“friendly-fire”). The BE-CAR7 approach overcomes this using base editing, a new-generation genome editing technique that precisely changes single letters of DNA code without cutting the DNA, minimizing the risk of chromosomal damage.

The BE-CAR7 T-cells are generated from healthy donor white blood cells (making them “universal” or “off the shelf”) through complex engineering steps utilizing a lentiviral vector to add extra DNA code and custom mRNA and RNA in an automated process:

1. Removing T-cell markers (Receptors and CD7): This step allows the donor cells to be used without matching the recipient and prevents “friendly-fire” against the therapeutic product itself.

2. Removing CD52: This makes the edited cells invisible to strong antibody drugs used to subdue the patient’s immune system.

3. Adding a Chimeric Antigen Receptor (CAR): A lentiviral vector is used to insert the DNA code for the CAR, which specifically recognizes the CD7 T-cell flag found on leukemic T-cells.

Once infused, the BE-CAR7 cells rapidly destroy all T-cells (including leukemic T-cells). If the leukemia is eradicated, the patient’s immune system is rebuilt via a subsequent bone marrow transplant.

Patient Success Story

Alyssa Tapley, 16, from Leicester, was the first patient in the world to receive the base-edited cell therapy in 2022. Having failed to respond to standard treatments, Alyssa is now three years disease-free and pursuing teenage life.

“Years later, we know it worked and I’m doing really well,” Alyssa stated. “My ultimate goal is to become a research scientist and be part of the next big discovery that can help people like me.”