Disparities in positive results and dissemination of randomized controlled trials in immuno-oncology

This cross-sectional and longitudinal analysis aimed to demonstrate the disparities in positive results and dissemination patterns of randomized controlled trials (RCTs) in global immuno-oncology (IO).

Phase II-IV RCTs with results reported by article publications registered on ClinicalTrials.gov in 2007-2018 studying immune checkpoint inhibitors (ICIs), adoptive cell transfer, cancer vaccines, and immune modulators were included.

Twenty-eight percent of trials were positive (72 of 258), most of which were pharma-sponsored and focused on ICI and multiple IO therapies in lung cancer, melanoma, and multiple cancer types. The recent period of trial start year, upfront registration, large sample size, high strictness score on corticosteroid/infection-related criteria, and survival endpoints were associated with positive results. Trials from Mainland China had a faster publication timeline of positive results but lacked study diversity or full reporting of negative results compared with US and multinational trials. Compared with phase II trials, phase III-IV trials had a higher average proportion of positive results (28.9% vs. 22.2%) and a more stable change over the past decade (23.65% vs. 49.24%). Positive trials yielded more secondary manuscripts (10 vs. 4), a shorter publication process of approximately two years (P < 0.001), and a superiority in the dissemination of journals with an h-index >90 (P < 0.001) compared with negative trials.

Disparities in positive result dissemination are widespread in IO RCTs and affected by trial features. We proposed improvements in upfront registration, procedural integrity, and adequate inclusion of rival trials reporting negative results within the earlier two years in future reviews.