Fig. 1.

In vivo therapeutic activity of PD-1 antibody in combination with cisplatin or gemcitabine. (A) HPNE/K-Ras^G12D cell line was incubated without (OFF) or with doxycycline for 24–72 h to induce mutant K-ras expression. K-ras (21 kDa), PD-L1 (45 kDa) and beta-actin (43 kDa) proteins were detected by immunoblotting. (B) Mouse pancreatic cancer (KPC) cells harboring K-ras^G12D mutation (2x10⁶ cells per injection) were inoculated in C57BL/6 mice. The mice were randomly divided into 6 groups (7 mice for each group). Drug treatment started on day 7. PD-1 antibody (PD-1Ab, 100 μg, i.p.), gemcitabine (Gem, 30 mg/kg; i.p.), and cisplatin (Cis, 3 mg/kg; i.p) were injected as indicated. The control mice were treated with PBS. (C-D) Tumor volumes are means ± SD, and were log-transformed before performing GLM analysis. The number on the right side of each curve indicates the number of tumor-free mice at the end of the study. Groups treated with PBS or PD-1Ab are same in (C) and (D). (E) Mice were inoculated with syngeneic PDAC, and divided into 6 groups for treatment with PBS, gemcitabine, cisplatin, and PD-1 antibody as indicated (3 mice/group). (F-G) Tumor tissues were processed on day 15 for TUNEL staining (green). DAPI was used to stain nuclei (blue). Representative images are shown in (G), and quantitative data are means ± SEM and shown in (F). *, P < 0.05; **, P < 0.01; ***, P < 0.001 (one-way ANOVA and Tukey post hoc test).