Gene-corrected regulatory T cell therapy for IL2RA deficiency

Bi-allelic germline deficiency of IL2RA causes a rare autoimmune disease with impaired regulatory T cell (Treg) function and interleukin-2 (IL-2) signaling. Definitive treatment is currently limited to allogeneic hematopoietic stem cell transplantation, which carries significant morbidity and mortality risks. We previously identified a family with three siblings affected by compound heterozygous mutations in their IL2RA gene, resulting in dysfunctional Tregs. Here, we introduce a novel therapeutic approach involving ex vivo generation of gene-corrected autologous regulatory T cells (gcTregs). One of the two disease-causing mutations in patient-derived Tregs was corrected with CRISPR-Cas9-mediated homology-directed repair, restoring IL2RA expression. The resulting gcTregs demonstrated robust suppressive activity in vitro. Clinical-scale manufacturing from a patient with IL2RA deficiency showed efficient gene correction, restored IL2RA expression, and functional equivalence to healthy donor Tregs. This work establishes a Good Manufacturing Practice-compatible manufacturing process for personalized gcTreg therapies, potentially providing a safer treatment option for patients with IL2RA deficiency as well as a framework for treating other inborn errors of immunity.