Figure 1.

IL-6 blockade impairs the therapeutic efficacy of a therapeutic cancer vaccine. (A) The serum level of IL-6 (pg/mL) in TC-1.contol and TC-1 IL-6 tumor-bearing mice at different time points after tumor challenge. (B) The serum level of IL-6 (pg/mL) in TC-1.contol and TC-1 IL-6 tumor-bearig mice with and without IL-6R blockade or isotype control at day 16 post-tumor challenge. Tumor outgrowth graphs of the untreated or SLP vaccinated TC-1.control (C) and TC-1.IL-6 (D) tumor-bearing mice treated with or without IL-6 or IL-6R antibodies as described in the material and methods. The number shown above the x-axis is the number of alive mice from the total. (E) The average tumor outgrowth (upper panel) and the mean response rate (%) according to RECIST criteria (upper panel) of the major groups shown in (D). Lower panel: NR, no response; PR, partial response; CR, complete response. Graphs indicate mean values with SEM (F) survival graph of the mice shown in (D). Data in (A, B) is representative of three independent experiments, yielding similar results. Data shown in C–F are pooled from four independent experiments with similar results. Significance was determined by Mann-Whitney U test in B and student unpaired t-test for difference in endpoint tumor size in the vaccinated groups and χ² for trend for response rate in (E). Significance was determined by a log-rank (Mantel–Cox) test in (F). *P<0.05; **p<0.01; ***p<0.001. IL-6, interleukin 6; SLP, synthetic long peptide.