Effect of MDM2is on EBV-positive lymphoma cells derived from patients with PTLD. TRL1 and TRL595 were derived from tumors of patients with PTLD. (A) Dose response to navtemadlin and idasanutlin. Dose-response analysis was performed as described for Figure 4. The data are presented as the mean ± SD of a quadruplicate assay. (B) Protein levels were determined by western blot analysis. Controls were at basal levels; Navt samples were treated with 1 µM navtemadlin for 24 hours. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as loading control. (C) In vivo treatment response. Animals were enrolled onto the study when tumors reached 200 mm³ and were treated once per day for 21 days. Top: tumor volume changes for each mouse. Bottom: tumor volume changes at day 21 (end of treatment). P < .01 for TRL1. (D) Tumor nodules in liver of TRL595 mice. PARP, poly(ADP-ribose) polymerase.