In vivo site-specific engineering to reprogram T cells - Nature

"Using CRISPR-Cas9 and adeno-associated virus (AAV)-mediated homology-directed repair, we targeted CAR integration into the endogenous human TCR alpha locus (TRAC). TRAC-CAR T cells display dynamic CAR expression that delays exhaustion and improves tumour control in xenograft and immunocompetent models. This work has been critical for the development of allogeneic CAR T cell therapy, as it disrupts the TCR after transgene insertion—a necessary step to limit graft-versus-host disease."

"Allogeneic approaches could address manufacturing limitations by creating off-the-shelf products from healthy donors. However, allogeneic CAR T cells are eventually rejected and frequent relapses have been observed."

"Direct in vivo CAR T cell generation may circumvent hurdles associated with leukapheresis and manufacturing. It might also promote the formation of a less differentiated CAR T cell pool, a feature associated with improved antitumour activity."

CAR T cell therapy shows promise for treating blood cancers, with seven FDA-approved therapies available. However, standard approaches require patient-specific manufacturing, resulting in variable quality, extended production times, and high costs. Researchers used CRISPR-Cas9 and AAV-mediated homology-directed repair to precisely integrate CARs into the TRAC locus, creating cells with dynamic CAR expression that delays exhaustion and improves tumor control. This targeted integration disrupts the TCR, a critical requirement for allogeneic CAR T cell therapy from healthy donors. While allogeneic approaches offer manufacturing advantages as off-the-shelf products, they face eventual rejection and frequent relapses. Direct in vivo CAR T cell generation presents an alternative strategy to overcome manufacturing limitations and potentially generate less differentiated cells with enhanced anti-tumor activity.

Read at Nature