Quality evaluation of investigator‐initiated trials using post‐approval cancer drugs in Japan

Investigator‐initiated trials (IIT) are important aspects of medical research and have contributed substantially to modern oncology. IIT using post‐approval drugs have been conducted by domestic institutions in Japan. Data from the present study were obtained by all IIT registered clinical trials for five cancers (lung, colorectal cancer, gastric cancer, liver cancer, and breast cancer) using drugs approved from 1999 to 2009 in Japan. Kaplan–Meier method, analysis of variance (anova), and Kruskal–Wallis test were used to estimate time to enrolment completion (TTEC) and time to enrolment per patient (TTEP). Of 1222 trials eligible for analysis, 465 trials (38%) completed enrolment to the studies, and 203 trials (17%) published results. In the distribution according to trial phase, 98 (8%) were phase I, 1058 (87%) were phase I/II + II, and 66 (5%) were phase II/III + III. Accrual achievement and publication rates were higher in late‐phase than in early‐phase trials. Median TTEC was 1387 days (95% confidence interval [CI], 1302–1472). Median TTEP was 38.5 days (95% CI, 34.5–42.5). The median TTEC and TTEP were significantly different in each trial phase (P < 0.01), funding source (P < 0.01), and publication status (median TTEC published trials versus unpublished trial; 720 days vs 1672 days, median TTEP; 16 days vs 55.8 days; P < 0.001). Many IIT using approved cancer drugs have been conducted; however, the quality of the clinical trials was low in terms of accrual achievement, publication rate, and time to publication of trial results.