Exercise Delays Human Leukemia Progression and Mitigates Graft-Versus-Host Disease After Donor Lymphocyte Infusion in Xenogeneic Mice

<b>Background:</b> Donor lymphocyte infusion (DLI) is employed to enhance the graft-versus-leukemia (GvL) effect and improve remission rates following allogeneic hematopoietic cell transplantation (alloHCT). However, graft-versus-host disease (GvHD) remains a significant complication of both alloHCT and DLI. Regular exercise has been shown to reduce cancer risk, enhance treatment responses, and mitigate therapy-related toxicities. This study investigated the effects of voluntary wheel running on GvL and GvHD following DLI in a xenogeneic mouse model. <b>Methods:</b> Immunodeficient NSG-IL15 mice were challenged with a luciferase-expressing chronic myelogenous leukemia cell line (K562), and then they received DLI with peripheral blood mononuclear cells (PBMCs) from healthy volunteers (GvL model). Non-tumor bearing mice received DLI to model GvHD. Half of the mice in each group were then given free access to a running wheel. Tumor growth (bioluminescence), GvHD, and body weight were monitored biweekly for ~40 days. <b>Results:</b> In the GvHD model, exercise extended overall survival by 60% and reduced GvHD severity. In the GvL model, exercise significantly lowered tumor burden and extended tumor-free survival in both DLI and vehicle control groups by 44.5% and 37.5%, respectively, suggesting both immune-dependent and immune-independent mechanisms. RNA sequencing of bone marrow from saline-injected mice revealed that genes associated with mitochondrial function, protein synthesis, and metabolic processes were downregulated in tumors from exercised mice. <b>Conclusions:</b> In summary, voluntary wheel running improved DLI outcomes by enhancing GvL and reducing GvHD. These benefits may be mediated, in part, through exercise-induced metabolic reprogramming of leukemia cells.