Figure 4. In vivo antitumor activity in systemic treatments.

(A) Mice were grafted i.v. with 700,000 B16-HER2 cells and i.v. treatment was started 48 hours later. Mice were injected 5 times i.v. every 3–4 days (arrows) with either PBS (control), equimolar amounts of αGalCer (0.4 μg), or αGalCer-loaded sCD1d–anti-HER2 fusion (40 μg). Mice were analyzed after 3 weeks and results are shown as pictures of tumors-invaded lungs (1 representative lung per group; original magnification, ×6.3), and in the graph expressed as percent of lung surface invaded by melanin-loaded tumor nodules. Results represent the mean ± SD of 5 mice per group of 2 independent experiments. **P < 0.005 versus control; *P < 0.04 versus αGalCer. (B) Mice were grafted as above, and treatment was started 6 days after with the same protocol as in A including treatment with sCD1d (25 μg). Lung nodules were analyzed after 2 weeks. Results represent the mean ± SD of 6 mice per group of 2 independent experiments. ***P = 0.0006 versus control; **P < 0.004 versus αGalCer; *P < 0.02 versus sCD1d. (C) Mice were grafted s.c. on the right flank with 700,000 B16-HER2 cells and i.v. treatment as in B was started 7 days later, when all tumors were palpable. Additional groups treated with 4D5 alone (80 μg) or the combination of 4D5 + sCD1d (80 + 25 μg) were included. Results expressed as the mean tumor size in mm³ ± SD measured at the end of the treatment (day 18) of 4 mice per group. Statistical significance of αGalCer/sCD1d–anti-HER2–treated group was of *P < 0.05 versus all other groups.