The insufficient publication of early-phase clinical trials in oncology.

Two retrospective cohorts were formed: one included early-phase trials supporting European Medicines Agency marketing authorization applications (2017-2020), while the second cohort included early-phase trials of discontinued compounds. Trials were matched with database registry and their corresponding publications.

Timely and complete publication of early-phase clinical trial results remains inadequate. Forty percent of trials with discontinued drugs are not publicly reported, and even among approved compounds, 11% of early-phase trial results cannot be found in the public domain.

The first cohort consisted of 73 trials. Nine ongoing trials were excluded. No full publication or full report was found for 11% (n = 7/64) of trials. Median time from registered closure date to publication of trial results as full publication or full report was 109 days [IQR -733-597]. Trials sponsored by large size firms (HR 2.25 [95%CI 1.23-4.1]), with >100 patients (HR 2.15 [95%CI 1.19-3.88]) and duration >2 years (HR 6.83 [95%CI 3.03-14.38]) were more likely to be published. The cohort with discontinued compounds consisted of 66 clinical trials. After exclusion of nine ongoing trials, 39% (n = 22/57) lacked full publication or full report. Median time from registered closure date to publication of trial results as full publication or full report was 702 days [IQR 263-2200]. No covariates influencing publication status were found.

Early-phase oncology clinical trials are often underrepresented in studies regarding publication of trial results. This study investigated the publication status of early-phase clinical trials, focusing on trials of compounds discontinued in clinical development.