Figure 4.

Impact of combining JQ1 and PD-1 on TH-MYCN tumor volume and mice survival. (A) Experimental design of JQ1 and anti-PD-1 treatment of TH-MYCN tumor-bearing mice showing the schedule and dosing. Following the development of homozygote TH-MYCN tumors, the tumor volume was assessed by MRI in all mice. Mice were randomly assigned into four groups: vehicle- and isotope-treated group (n = 9), vehicle and anti-PD-1-treated group (n = 8), JQ1 and isotype-treated group (n = 8), and JQ1 and anti-PD-1-treated group (n = 8). Mice were treated daily from days 1 to 7 with either vehicle (group 1 and 2) or JQ1 (group 3 and 4) and on days 1, 4, 7, 10 and 13 with either isotype (group 1 and 3) or anti-PD-1 (group 2 and 4). After day 15, only the treatment with isotype or anti-PD-1 was continued using the same schedule until the end of experiment (mice euthanasia). JQ1 (25 mg/kg/day) and anti-PD-1 (10 mg/kg/day) were administered by IP. MRI was performed on days 1, 4, 8 and 15 post-treatment and on a regular basis to determine the tumor volume. (B) Representative images of TH-MYCN tumor-bearing mice on days 1, 4, 8 and 15 for the groups described in (A). On day 15, no images for groups 1 and 2 are provided as animals died. Abdominal tumor masses are delineated in red. (C) Volumes of TH-MYCN tumors on days 1, 4 and 8, and in mice treated with JQ1 and isotype or JQ1 and anti-PD-1. Each dot represents one tumor. Results are shown as mean ± SEM (error bars). Statistically significant differences are calculated compared to the control group (JQ1 and isotype) using an unpaired two-tailed Student’s t-test (ns: not significant *: p < 0.05). (D) Mice survival curves were generated from tumor-bearing mice treated with JQ1 and isotype or JQ1 and anti-PD-1. Lack of survival was defined as death or tumor size > 2000 mm³. The probability of survival was defined using GraphPad Prism, and p-values were calculated using the log-rank (Mantel-Cox) test (* p ≤ 0.05).