Study timeline is shown in (A). MT5 murine pancreatic tumor cells were s.c. injected into C57BL/6 mice with treatment beginning when tumors reached 50–100 mm³. Mice were treated with 200 mg (i.p. injection 3 times/week) of isotype control, cytokine blockade anti–IL-6 and/or anti–CTLA-4 Abs (n = 5 mice/group) until mice met prespecified IACUC-approved early removal criteria. (B) Changes in tumor volume as determined by caliper measurement throughout the course of Ab treatment. Mean ± SD; *P < 0.05 versus isotype control; ‡P < 0.05 versus anti–IL-6; and †P < 0.05 versus anti–CTLA-4 using mixed-effects regression. (C) Representative 20× images of IHC staining for CD3 in FFPE tumor tissue slices from mice in the different treatment groups. (D) Mean ± SD for percent of cells expressing CD3⁺ in s.c. tumors per high-powered field. Symbols represent individual mice; * indicates significance compared with isotype control-treated mice. P values for significant comparisons with ANOVA and LSD for pairwise comparisons are as follows: isotype versus α–IL-6 (0.0013); isotype versus α–CTLA-4 (0.0058); and isotype versus α–IL-6 + α–CTLA-4 (0.0058). (E) Splenocytes were isolated from the mice receiving treatment as stated in B. Flow cytometry was performed with Abs against CD4, CCR6, CXCR3, CCR4, and RORγt. CD4⁺CCR6^–CXCR3⁺CCR4^– were identified as suggestive of a Th1 phenotype and CD4⁺CCR6^–CXCR3^–CCR4⁺ as a Th2 phenotype. (F) Graph of mean percentages of CD4⁺ T cells that have a Th1 or Th2 phenotype. Data shown as mean ± SD; * indicates significance compared with isotype control-treated mice with ANOVA and LSD for pairwise comparisons. P values for significant comparisons are as follows: isotype versus α–CTLA-4 (< 0.0001); isotype versus α–IL-6 + α–CTLA-4 (0.0004); α–IL-6 versus α–CTLA-4 (0.0026); and α–IL-6 versus α–IL-6 + α–CTLA-4 (0.0278).