Fig. 1
C215Fab-SEA significantly inhibited tumor growth, increased survival and induced a broad protective polyclonal immune response against tumor rechallenge. A Schematic illustration of the dosing regimens for the in vivo study. Mice were subcutaneously (s.c.) injected with 5X105 MC38-hEpCAM tumor cells and were randomized on Day 7 (≈ 60 mm3 mean tumor volume) into treatments of C215Fab-SEA (15 μγ/mouse; i.p.), anti-PD1 mAb (50 μγ /mouse; i.p.) or combined therapy. After each treatment cycle, tumors were taken for immune phenotyping analysis. B Individual tumor growth kinetics of mice from the control and treated groups. TF = Tumor free. C Kaplan‒Meier overall survival curves of each treatment group. Survival data were evaluated for statistical significance with the log-rank Mantel‒Cox test. *p < 0.05; **p < 0.01; ****p < 0.0001. D On Day 100 after tumor inoculation, TF mice were rechallenged with 5 × 105 MC38-hEpCAM injected (s.c.) in the right flank and challenged with 5 × 105 MC38 parental cells (hEpCAM negative) in the left flank. The hEpCAM negative challenge tests whether the protective memory is broad and polyclonal, as hEpCAM is the target of C215Fab-SEA. For comparison, naïve mice were also challenged with both cell lines. E Mean (± SEM) tumor volume of MC38-parental (left) or MC38-hEpCAM (right) in naïve mice (black), TF mice of C215Fab-SEA monotherapy (green) and TF mice of combination therapy (red). F On Day 100 after tumor inoculation, TF mice were rechallenged with 5X105 MC38 parental cells injected (s.c.) in the right flank and challenged with 2.5 × 106 E0771 cells in the left flank. The challenge tests whether the protective memory is specific to MC38-associated antigens. For comparison, naïve mice were also challenged with both cell lines. G Mean (± SEM) tumor volume of E0771 breast tumor (left) or MC38-parental colon (right) in naïve mice (black) and TF mice of C215Fab-SEA monotherapy (green). In all figures, timepoints are referred to as C1-C4 (cycles 1-4, respectively). Data are representative of at least 3 independent experiments