A differentiated and durable allogeneic strategy applicable to cell therapies

Autologous T-cell therapies have shown profound clinical responses; however, their widespread use has been limited primarily as the result of their individualized manufacturing requirements.

To develop a persistent "off-the-shelf" allogeneic (Allo) approach, a multiplex Nme2Cas9-based cytosine base editor was deployed to knockout select human leukocyte antigens (HLA) class I and II alleles (HLA-A, HLA-B and the class II transactivator [CIITA]) while retaining HLA-C to protect from natural killer (NK) cell rejection.

Matching the residual HLA-C allele from homozygous donors to the host prevented rejection of the donor T cells by allogeneic host T and NK cells. Site-specific integration of a tumor-specific CAR or TCR into the TRAC locus using SpyCas9 nuclease and an adeno-associated virus template allowed for a high localized insertion rate while simultaneously removing the endogenous TCR and preventing graft-versus-host disease. Using an optimized T-cell engineering process involving orthogonal CRISPR/Cas9 cleavage and base editors coupled with lipid nanoparticle delivery, we achieved efficient production of Allo-CAR T cells with high editing rates and cell expansion in a scalable manner. These allogeneic T cells demonstrated comparable functional activity to their autologous counterparts in preclinical assays. Moreover, this gene-editing approach significantly minimized the occurrence of chromosomal aberrations. This promising allogeneic approach also has been applied to induced pluripotent stem cells (iPSCs) with triple edits targeting HLA-A, HLA-B and CIITA (TKO). Pancreatic progenitor cells or cardiomyocytes derived from TKO iPSCs were protected from host peripheral blood mononuclear cell-mediated rejection when matched for HLA-C, suggesting potential applications in regenerative medicine applications.