bioRxiv : the preprint server for biologyDec 25, 2025

Fixing a single genetic mutation in A20 may improve CAR-T cell cancer therapy

CRISPR Gene Editing Weekly Brief ↗PubMed ↗DOI ↗

Updated Jun 27, 2026

Abstract

Essence

Base-editing one A20 missense mutation made CAR-T cells more resistant to exhaustion and more suppressive against cancer in the reported models.

Evidence

This was a preclinical immunotherapy study using genome-wide screening in repetitively stimulated human T cells, protein modeling, deep base-editing mutagenesis, immunocompetent mouse studies, tumor-infiltrating lymphocyte analyses, and engineered human CAR-T cells.

Caveat

The evidence combines cell and mouse-model systems, so the CAR-T efficacy signal is preclinical and not yet human clinical outcome evidence.

Simplified

T cell exhaustion limits the efficacy of cancer immunotherapies. Here, we performed genome-wide loss-of-function screening in repetitively stimulated human T cells and identified the mulitfunctional ubiquitin-modifying protein A20/TNFAIP3 as a major negative regulator of exhausted T cell persistence. Protein large language modeling, deep base-editing mutagenesis, and studies in immunocompetent mice with domain-specific inactivating mutations revealed A20's non-enzymatic M1 ubiquitin-binding zinc finger 7 (A20) motif as critical to suppression of anti-tumor immunity. A20-deficient CD8tumor-infiltrating lymphocytes (TILs) resisted terminal exhaustion and circumvented an unappreciated mechanism restraining perforin degranulation in terminally exhausted cells. Human chimeric antigen receptor (CAR)-T cells engineered via base-editing to inactivate A20via a single missense mutation also resisted exhaustion, secreted more perforin and robustly suppressed cancer. These studies pinpoint A20as a novel T cell checkpoint and reveal precision base-editing of missense mutations as an effective approach to enhance CAR-T cell therapy. ZF7ZF7 + ZF7ZF7in vivo