Statistical analysis
Overall survival (OS) was calculated using the Kaplan–Meier method from the first day of IREC administration to death or the last follow-up visit. The cumulative incidence of relapse and non-relapse mortality was calculated using the Gray test. We used the Chi-squared test to analyze categorical variables and the Mann–Whitney U test to analyze continuous variables. All statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University), which is a graphical user interface for R (The R Foundation for Statistical Computing, Vienna, Austria)14.