AUY922 treatment preserves donor T-cell–mediated GVL effects. Lethally irradiated BDF1 recipients (11.5 Gy) received B6/SJL mouse–derived TCD-BM (5 × 10⁶) transplants with or without spleen cells (1 × 10⁷) and challenged with A20^TGL cells (1 × 10⁶). Fourteen doses of AUY922 were administered from day 0 to day 27 after transplantation. (A-B) In vivo image analysis on days 14, 22, and 42 after transplantation. Graph shows the total-body luminescence intensity. (C) Survival rate was monitored over time. (D) Donor T cells were recovered on day 7 after transplantation. Graphs show the fractions of TNF-α– and IFN-γ–producing donor CD4⁺ and CD8⁺ T cells. (E) Donor T cells isolated from the spleen on day 14 were used for cytolytic assay against A20^TGL cells. Error bars indicate mean ± standard deviation. Data are representative of 2 to 3 independent experiments. *P < .05; **P < .01; ***P < .001.