Wiebking, VolkerLee, Ciaran M.Mostrel, NathalieLahiri, PremanjaliBak, RasmusBao, GangRoncarolo, Maria GraziaBertaina, AlicePorteus, Matthew H.2021-04-212021-04-212021Wiebking, Volker, Lee, Ciaran M., Mostrel, Nathalie, et al.. "Genome editing of donor-derived T-cells to generate allogenic chimeric antigen receptor-modified T cells: Optimizing αβ T cell-depleted haploidentical hematopoietic stem cell transplantation." <i>Haematologica,</i> 106, no. 3 (2021) Ferrata-Storti Foundation: https://doi.org/10.3324/haematol.2019.233882.https://hdl.handle.net/1911/110289Allogeneic hematopoietic stem cell transplantation is an effective therapy for high-risk leukemias. In children, graft manipulation based on the selective removal of αβ T cells and B cells has been shown to reduce the risk of acute and chronic graft-versus-host disease, thus allowing the use of haploidentical donors which expands the population that allogeneic hematopoietic stem cell transplantation can be used in. Leukemic relapse, however, remains a problem. T cells expressing chimeric antigen receptors can potently eliminate leukemia, including in the central nervous system. We hypothesized that by modifying donor αβ T cells to simultaneously express a CD19-specific chimeric antigen receptors and inactivating the T cell receptor by genome editing, we could create a therapy that enhances the anti-leukemic efficacy of the stem cell transplant without increasing the risk of graft-versus-host disease. Using genome editing with Cas9 ribonucleoprotein and adeno-associated virus serotype 6, we integrate a CD19-specific chimeric antigen receptor in-frame into the TRAC locus. Greater than 90% of cells lost TCR expression, while >75% expressed the CAR. The product was further purified to ultimately have less than 0.05% residual TCR+ cells. In vitro, the CAR T cells efficiently eliminated target cells and produced high cytokine levels when challenged with CD19+ leukemia cells. In vivo, the gene modified T cells eliminated leukemia without causing xenogeneic graft-versus-host disease in a xenograft model. Gene editing was highly specific with no evidence of off-target effects. These data support the concept that the addition of αβ T cell-derived, genome edited T cells expressing CD19-specific chimeric antigen receptors could enhance the anti-leukemic efficacy of αβ T cell-depleted haploidentical hematopoietic stem cell transplantation without increasing the risk of graft-versus-host disease.engThis work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.Journal article9701-71341-2-10-20210222https://doi.org/10.3324/haematol.2019.233882