2.13. Non‐small‐cell lung cancer xenograft model

Ba/F3 (EML4‐ALK‐WT) cells in logarithmic phase were utilized in this study. Adherent cells were digested, harvested, counted, and resuspended in PBS. The density of cells was adjusted to 5.0 × 10⁷ cells/mL. Tumor cell suspension (100 μL/mouse) was implanted carefully s.c. into the right flank of the back of C3H mice. When the tumors reached 100 mm³ approximately 10 days after inoculation, mice were randomized into 4 groups (8 mice/group) and give an i.p. injection or gavage (p.o.) of vehicle (5% methylcellulose), CER (25 mg/kg, p.o., qd × 5), PD‐L1 inhibitor (PDL1, 10 mg/kg, i.p., q2w × 3), and combination (CER, 25 mg/kg, p.o., qd × 5; PDL1, 10 mg/kg, i.p., q2w × 3). The doses were determined on the basis of previous studies. ²⁸ Tumor volume was measured and determined every 2 days by electronic caliper measurements. The calculation method was according to the formula (length × width²)/2, where length represents the larger tumor diameter and width represents the smaller tumor diameter. Mice were monitored twice weekly for body weight and daily for general condition. The percentage of ∆T/C (% of control for ∆growth) was calculated using the following formula: (∆T/∆C) ×100%, where ∆T and ∆C are the changes in tumor volume (∆growth) for the treated and control groups, respectively. ²⁹ The experiment was terminated when the size of tumors in either the treated or control group reached 2000 mm³. After approximately 20 days, mice were killed under deep anesthesia and tumors were immediately harvested and weighed. All animal experiments were approved by the Institutional Committee for Animal Care and Use, Capital Medical University, and were undertaken in good accordance to the institutional guidelines.