Figure 6. The humanized MHC-dKO NSG model is suitable for testing the long-term efficacy of T-cell engagers, including tumor-rechallenge experiments. (A) Schematic representation of the experiment. The irrelevant control plasmid contained the sequence for an anti-HIV-1/CD3 antibody, considered irrelevant in this model. (B) EFS analysis by experimental groups. Control mice with HT29 tumors with no PBMCs were not represented for simplification. (C) mALT plasma levels at day +11 of the experiment. The dashed line represents the upper limit of normality (50 U/L). Control mice with HT29 tumors with no PBMCs were not represented for simplification (no >50 U/L mALT levels detected). (D) Individual tumor growth curves. The dashed line at 15 mm represents the tumor burden limit for a humane endpoint. (1): one of five mice in the HT29+PBMCs + αEpCAM/CD3 pl. group was found dead at day +8 with no previous signs of xenograft-versus-host disease. (E) Tumor growth curves of the experimental groups. The dashed line at 15 mm represents the tumor burden limit for a humane endpoint. (F) Individual tumor growth curves in mice rechallenged with HT29 tumor cells. “Tumor-naive” represents control mice engrafted with the same PBMCs as tumor-rechallenged mice at the same day but not exposed previously to HT29 tumor cells. αEpCAM/CD3, anti-epithelial cell adhesion molecule/CD3; CR, complete response rate; dKO, MHC-dKO NSG mice; EFS, ≥20% body weight loss event-free survival; h.d., hydrodynamic administration; hIFN-γ, human interferon gamma; i.v, intravenous; Irr. pl., irrelevant plasmid (B12/CD3 bispecific antibody); mALT, mouse alanine aminotransferase; MHC, major histocompatibility complex; PBMC, peripheral blood mononuclear cells; pl., plasmid; s.c., subcutaneous; Φ, diameter.