Fig. 1

Induced TiRP tumors resist immunotherapy. a Schedule for tumor induction and immunotherapy. TiRP mice (B10.D2;Ink4a/Arf^flox/flox;TiRP^+/+) injected twice with 4 mg 4OH-tamoxifen on day 0 and 15, were also injected as indicated with anti-CTLA4 (4 × 40 µg) and/or anti-PD1 (4 × 200 µg) and/or a prime/boost vaccine regimen of recombinant adenovirus (Adeno.Ii.P1A_t) and Semliki Forest virus (SFV.P1A) encoding the MAGE-type tumor antigen P1A. Tumor appearance and mice survival were monitored. The figure represents the cumulative data of three experiments. b Tumor-bearing TiRP mice and control mice (B10.D2;Ink4a/Arf^flox/flox mice, which have the same genetic background as TiRP mice but lack the TiRP transgene) were immunized with the P1A vaccine as above, and the P1A-specific CD8⁺ T-cell response was monitored by FACS in spleen cells stimulated one week with P1A-peptide pulsed spleen cells, using antibodies to CD3ε and CD8α, and H-2L^d-P1A tetramers. Five mice were analyzed at each time point for each group. c TiRP mice were immunized simultaneously against P1A as above and against the irrelevant H-2L^d-restricted antigen P91A (mutated peptide) by intramuscular injections of P91A peptide in AS15 adjuvant⁵² one week apart during 1 month. Mice were then treated with 4OH-tamoxifen. At the time of tumor appearance, spleen cells were stimulated one week with P1A or P91A peptide-pulsed spleen cells, and P1A- or P91A-specific CD8⁺ T cells were quantified by FACS analysis using the relevant H-2L^d tetramers. Results are expressed as mean + s.e.m. Unpaired t-test, two-tailed c, *P < 0.05, **P < 0.01