CD40 Agonist on Patient-Derived Xenograft Mice for the Treatment of B-Cell Acute Lymphoblastic Leukemia

Abstract Purpose: Cluster of differentiation 40 (CD40) is expressed on B-cell acute lymphoblastic leukemia (B-ALL) cases. However, the effect of CD40 activation on B-ALL cells has never been tested in vivo. Experimental Design: The aim of our preclinical study was to investigate the therapeutic potential of a CD40 agonist in the treatment of B-ALL using patient-derived xenograft mouse models. Results: Intravenous administration of the CD40 agonist significantly impeded B-ALL cell proliferation and growth in vivo, accompanied by rapid activation of the ERK pathway, which led to the induction of apoptosis and disruption of cell-cycle progression. Cotreatment with a specific inhibitor of ERK further demonstrated that CD40 stimulation induced the proapoptosis of B-ALL cells in an ERK-dependent manner. Proteomic analysis revealed alterations in key signaling pathways associated with B-ALL expansion and maintenance. Moreover, the CD40 agonist markedly reduced the frequency of leukemia-initiating cells and leukemia development in patient-derived xenograft mice. Our study showed that the CD40 agonist can be associated with chemotherapeutic agents such as vincristine and dexamethasone, and this combination showed improved effectiveness. Additionally, the CD40 agonist was more effective on pre–B-ALL (EGIL B-III) that expressed CD40 than on common B-ALL (EGIL B-II) that lacked CD40 expression. Conclusions: These findings suggest that CD40 agonists are promising immunotherapeutic candidates for pediatric B-ALL, warranting further clinical investigations to improve patient outcomes in CD40-expressing B-ALL.