Syngeneic tumor mouse models

Cohorts of 6–7 weeks old female black C57BL/6, white BALB/c, or nude BALB/c mice were purchased from Vital River Laboratory Animal Technology (Beijing, China). Mice were first kept for an acclimation period of 7–14 days in a controlled pathogen-free environment before study began. Mouse KPC pancreatic cancer cells (1-2x10⁶) or CT26 colon cancer cells (0.3x10⁶) were injected into the right flanks of the 7–8 weeks old mice. Before drug administration, mice were randomly divided into the indicated groups without blinding. For drug treatment, anti-mouse PD-1 antibody (BioXcell, West Lebanon, NH, USA; #BE0146), cisplatin (Hospira, Lake Forest, IL, USA; CAS 15663-27-1), and gemcitabine (Eli Lilly and Company, Indianapolis, IN, USA; CAS 122111-03-9) were administrated twice a week for 3 weeks as indicated. Body weights and tumor volumes were measured twice per week. Tumor volume was calculated using the following formula: tumor volume (mm³) = (length (mm) × width² (mm))/2. Moribund mice or animals with tumors of greater than 15 mm in length or with ulcerated tumors were promptly sacrificed to avoid unnecessary pain and suffering.