PKT16 reduces in vivo CLL tumor burden. (A) Nude mice were transplanted with OSU-CLL cells, as indicated in"Methods." When the tumors reached 60 to 150 mm², mice received intraperitoneal injections of the control peptide 4NGG or PKT16 (10 mg/kg, 5 days per week), and tumor volume was measured at the indicated time using a caliper. The data are presented in the graph as the mean ± SEM (n = 8 mice per group). Contrary to 4NGG treatment, PKT16 significantly reduced the tumor volume. The percentage of tumor growth inhibition was calculated and depicted in a plot. P values correspond to statistical differences between the 4NGG and the PKT16 groups. (B) The probability of tumor progression overtime (RTV) after 4NGG and PKT16 mice treatment was represented as a curve and plotted. The graph indicated the probability of the OSU-CLL tumors to increase 6 times their volume after 4NGG or PKT16 treatment (RTV x 6). (C) Count of red blood cells (RBC), white blood cells (WBC), and platelets in 4NGG- and PKT16-treated OSU-CLL xenotransplanted mice (15 days of treatment, 8 mice per group). (D) Percentages of granulocytes, monocytes, and lymphocytes recorded after 15 days of treatment in 4NGG- and PKT16-treated mice (n = 8 mice per group). (E) Hemoglobin (Hb) concentration, hematocrit percentage, and mean cell volume (MCV) were assessed in 4NGG- and PKT16-treated mice (15 days of treatment). Box plots represent the mean of the data recorded in each population with minimum to maximum values (n = 8 mice per group). (F) Histological analysis of liver, kidney, spleen, and lymph nodes of 4NGG- and PKT16-treated mice at 15 days of treatment. Tissue sections were stained with hematoxylin-eosin-saffron. Representative images are shown. The statistical analysis included in this figure was performed with the Student t test, except panel B performed with the Wilcoxon test. Symbols and bars in panels A and B represent mean ± SEM.