Evaluating xenograft mouse models for preclinical assessment of adoptive T cell transfer

Humanized mouse models are crucial for preclinical testing of adoptive cell transfer (ACT) strategies in cancer immunotherapy. A key challenge is identifying models that enable efficient human T cell engraftment while minimizing graft-versus-host disease (GVHD), which hinders long-term assessment of T cell functionality. The immunodeficient NOD/SCID/IL-2Rγnull (NOG) mouse strain with transgenic expression of human interleukin-2 (hIL-2-NOG) has recently been proposed as a promising model for ACT, since it supports engraftment and promotes T cell survival in vivo. However, in the present study we found that hIL-2-NOG mice adoptively transferred with ex vivo-expanded human T cells, rapidly developed GVHD in a dose-dependent manner. Comparing adoptive transfer of fresh and cryopreserved human T cells in hIL-2-NOG, parental NOG and NOG mice with a beta-2-microglobulin deletion (B2m-NOG) that delays GVHD onset, demonstrated that engraftment and GVHD induction were limited to hIL-2-NOG mice, while NOG and B2m-NOG showed poor donor T cell engraftment. Cryopreservation delayed GVHD onset in hIL-2-NOG mice, likely due to reduced T cell viability and functionality. Additionally, introducing a tumor expressing the T cell target antigen enhanced T cell engraftment in NOG mice, indicating that antigen recognition can improve survival and persistence of transferred T cells. These findings suggest that several factors influence the capacity of human T cells to engraft following adoptive transfer in xenogeneic mouse models, including the genetic background of recipient mice, and the quantity and functionality of transferred T cells. Thus, these factors should be considered when choosing a preclinical mouse model for evaluation of ACT strategies.