Results reporting and primary endpoint achievement in interventional therapeutic trials for pleural mesothelioma, 2005–2025: a cross-sectional analysis

Abstract

Pleural mesothelioma (PM) is a rare and aggressive malignancy in which therapeutic progress depends on a limited clinical trial evidence base. Although trial registration has improved transparency, the extent to which registered trials generate publicly available and clinically interpretable evidence remains unclear. We evaluated results reporting, primary endpoint achievement, and trial characteristics according to reporting status in registered interventional therapeutic trials for PM. We conducted a cross-sectional analysis of registered interventional therapeutic trials for PM on ClinicalTrials.gov from 2005 to 2025. Trial characteristics, completion status, public results reporting, and whether the prespecified primary endpoint was met were abstracted from ClinicalTrials.gov and complementary public sources. Reporting and primary-endpoint analyses included trials with a primary completion date at least 12 months before data abstraction. Trials were considered reported if results were publicly available from any source. Primary endpoint achievement was defined according to whether the prespecified primary endpoint was reported as met, without reclassification based on perceived clinical relevance or secondary outcomes. Trial characteristics were compared descriptively according to reporting status using Fisher exact tests. We identified 150 interventional therapeutic trials, representing a planned cumulative enrollment of 12,406 participants. Immunotherapy-containing strategies increased from 2.7% of trials in 2005–2015 to 39.5% in 2016–2025. Among 114 trials that had reached primary completion, 28 (24.6%) had no publicly available results. In descriptive comparisons, nonreporting was more frequent among trials with planned enrollment below 50 participants and among nonrandomized studies. Among 86 trials with reported results, the prespecified primary endpoint was met in 33 (38.4%), not met in 41 (47.7%), and not evaluable in 12 (14.0%). Among randomized trials with classifiable primary-endpoint status, 9 of 27 (33.3%) met their prespecified primary endpoint. Registered interventional therapeutic trials for PM have increasingly shifted toward immunotherapy-containing strategies; however, incomplete public reporting and the limited proportion of reported randomized trials with classifiable outcomes that met their prespecified primary endpoints constrain clinical interpretation.