Epitope-specific inhibition of tumor growth and increased survival occurred after TRP-2180-188 + CpG vaccination combined with IL-2 in thymectomized mice after BMT. (A) Mice underwent BMT on day 0. Mice were injected subcutaneously with 100 000 B16F1 cells on day 14 after BMT. Also on day 14 after BMT, the regimen described in Figure 2A consisting of peptide + CpG + IFA vaccines and IL-2 was initiated. Tumor growth was inhibited in mice that received TRP-2180-188–containing vaccines compared with mice that were treated identically except that the negative control peptide OVA257-264 replaced TRP-2180-188 in vaccines. A statistically significant difference (P < .003) between the 2 groups occurred at the indicated (*) time points (TRP-2180-188 vaccinated, n = 14; OVA257-264 vaccinated, n = 13). (B) In the mice described in (A), overall survival was increased in mice that received vaccines containing TRP-2180-188 compared with mice that received vaccines containing the negative control peptide OVA257-264. (C) Mice underwent BMT on day 0. On day 14, the mice were injected with 10 000 B16F1 cells subcutaneously (a 10-fold lower dose of B16F1 than in the experiments described in A-B). Mice were then vaccinated and treated with IL-2 in an identical fashion as the mice described in (A). Mice that received vaccines containing TRP-2180-188 had increased survival compared with mice that received vaccines containing the negative control peptide OVA257-264. A fraction of mice that received vaccines containing TRP-2180-188 survived long term (greater than 6 months) without evidence of tumors. Both groups were treated identically except for the difference in peptide (TRP-2180-188 vaccinated, n = 15; OVA257-264 vaccinated, n = 13). (D) Mice underwent BMT and were injected with B16F1. One group received TRP-2180-188 + CpG–containing vaccines and IL-2 as described in Figure 2A, while a second group received identical regimens except that the negative control peptide OVA257-264 replaced TRP-2180-188 in vaccines. TRP-2180-188–specific CD8+ T-cell responses were detected at tumor sites of mice that received TRP-2180-188–containing vaccines, but not at tumor sites of mice that received OVA257-264–containing vaccines (TRP-2180-188–containing vaccines, n = 7; OVA257-264–containing vaccines, n = 6).