STxB-OVA or STxB-gp100 combined with the CCR4 antagonist partially protect against the growth of tumors in neu^OT-I/OT-II TG mice or B6 mice, respectively, in prophylactic or therapeutic settings. Neu^OT-I/OT-II TG mice were immunized with STxB-OVA mixed with αGalCer alone or combined with the CCR4 antagonist at day 0 and day 14 (A). The CCR4 antagonist alone was also administered in another group of mice at day 0 and day 14 without the vaccine (A). Another group of Neu^OT-I/OT-II TG mice was not treated but injected with PBS (A-B). In another experiment, Neu^OT-I/OT-II TG mice were immunized intraperitoneally twice (day 0 and day 14) with STxB-OVA/αGalCer combined with anti-CD25 (500 μg at day −3) or treated with anti-CD25 alone (B). At day 21, the EG7 tumor cell line (10⁶ cells) were subcutaneously grafted on the left flank (A-B). Six to 8 mice per group were used in each experiment, which was reproduced twice. (A) Arrow indicated the comparison side-by-side of the various groups of mice. (B) Statistical comparison was performed between the STxB-OVA + anti-CD25 and the anti-CD25 alone groups. *P < .05. (C) B16 melanoma cells (5 ×10⁵) were injected subcutaneously in the right flank of C57BL6 mice. Mice were then immunized by the intraperitoneal route at day 12 and day 19 after tumor graft, with the STxB-gp100_25-33 (30 μg) vaccine alone or combined with the CCR4 antagonist (1.5 μg). An other group was treated with the CCR4 antagonist alone, and a last group was not treated. In the 2 groups receiving the CCR4 antagonist (alone or combined with STxB-gp100_25-33), the CCR4 antagonist was administered intraperitoneally twice a week. Mice were monitored every 3-4 days for tumor growth. Five mice per group were used in each experiment. A representative experiment of 2 similar experiments is shown. Statistical analysis shown compared the 2 vaccinated groups (STxB-gp100 vs STxB-gp100 + the CCR4 antagonist). *P < .05, **P < .01.