(A) KPC1199 luciferase-expressing Slfn5-WT or Slfn5-KO cells (5 × 10⁴ cells/mouse) were injected into the pancreatic tails of male and female C57BL/6J mice. Mice were randomized into the following treatment groups: Slfn5 WT PBS (n = 7), Slfn5 WT IFN-α (n = 7), Slfn5 KO PBS (n = 7), and Slfn5 KO IFN-α (n = 8). Where indicated, mice were injected subcutaneously with 600 ng murine IFN-α per mouse once per week for 2 weeks. Tumor growth was monitored at least once per week by bioluminescence imaging (BLI). Normalized BLI values are shown. On day 17, model-based estimate of the mean difference in BLI signal between WT IFN-α and Slfn5-KO IFN-α was 3.91 × 10⁹ photons/s/cm²/sr (95% CI 1.72 × 10⁹ to 6.09 × 10⁹). Two-way ANOVA with Šidák’s multiple-comparison test for day 17. Comparison of BLI signals on day 17 is based on mixed-effects model up to day 17. Data are expressed as mean ± SEM of tumor BLI signals for each genotypic treatment group; ****P < 0.0001. (B) Survival curves of mice bearing Slfn5-WT and Slfn5-KO pancreatic tumors. Survival was estimated using the method of Kaplan-Meier and groups were compared using the log-rank test; **P < 0.01; ***P < 0.001; ****P < 0.0001. (C) Median survival time (days) for indicated genotypic treatment groups was estimated using Simple Survival Analysis (Kaplan-Meier) in GraphPad.