Rationale for setting the number of enrolled participants
EVENTS, DISEASE PROGRESSION
The study will randomize approximately 64 eligible patients 1:1 to durvalumab with anlotinib and durvalumab monotherapy group. The primary analysis of PFS (from randomization) will occur when approximately 50 progression events have been observed in the 64 randomized patients. If the true PFS HR for the comparison of durvalumab plus anlotinib versus durvalumab is 0.6 (5 vs. 3 m), 50 progression events will provide 70% power to demonstrate a statistically significant difference in PFS at a 20% two‐sided significance level. And assuming about 20% patients will experience disease progression in the first four cycles treatment (from CASPIAN) and 5% patients will lose of follow‐up, the overall sample size is 80.