DRI-C21045 (compound 10) is a potent and selective inhibitor of the CD40-CD40L costimulatory protein-protein interaction (PPI) with an IC 50 of 0.17 µM. DRI-C21045 shows concentration-dependent inhibition of the activation of NF-κB and B cell proliferation all induced by CD40L with IC 50 s of 17.1 µM and 4.5 µM, respectively In Vitro DRI-C21045 (3.2-100 μM; 18 h) concentration-dependently inhibits the CD40L-induced NF-κB activation in CD40 sensor cells. DRI-C21045 (0.6-50 μM; 48 h) blocks CD40L-induced functional activation of primary B cells. DRI-C21045 (0.4-50 μM; 48 h) inhibits CD40L-induced MHC-II upregulation in THP-1 cells. DRI-C21045 (2-100 μM; 48 h) inhibits CD40L-induced B cell proliferation. DRI-C21045 shows no signs of cytotoxicity for concentrations of up to 100 and 200 µM and has no genotoxic potential for concentrations of up to 500 µM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo DRI-C21045 (30 mg/kg; daily, s.c.; in 20% HPβCD) prolongs graft survival in a murine allogeneic skin transplant model . DRI-C21045 (20-60 mg/kg; twice daily s.c.; in 20% HPβCD) inhibits alloantigen-induced T cell expansion in the draining lymph nodes (DLNs) . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Full-thickness ear skins from BALB/c were transplanted onto the dorsal thorax of C57BL/6 Dosage: 30 mg/kg Administration: Daily s.c; administered in 20% w/v hydroxypropyl-β-cyclodextrin (HPβCD) solution Result: Caused prolongation of skin allograft survival. Form:Solid IC50& Target:IC50: 0.17 µM (CD40)