How to improve efficiency in IO clinical trials: Comprehensive analysis of a decade long reporting bias among 1867 trials.

Abstract

e14661 Background: Immunotherapy has transformed cancer treatment, offering curative potential while sparing patients from aggressive therapies like chemotherapy and surgery. Yet, challenges like poor reporting transparency and trial design undermine efficiency, causing redundancy, resource waste, and delayed progress in optimizing immunotherapy strategies. This study systematically evaluated IO trials over the past decade to uncover critical gaps in endpoint definition, publication rates, outcome transparency, and overall success rates of conducted clinical trials. Methods: We searched clinicaltrials.gov for IO interventional clinical trials that began after 01/01/2015 and completed by 01/01/2024. Trials were assessed for publication availability, endpoint clarity and explicitly reported outcomes. Publications were reviewed to determine if trial objectives, endpoints, and outcomes were clearly stated and reported as positive (primary endpoints met), negative (failed endpoints or unfavorable risk-benefit ratio), or unassessable due to insufficient reporting. Results: Among the 1867 trials, 1/3 were terminated, and 2/3 were completed. Nearly half (45%) of the trials lacked publications; 69% of completed trials had publications, yet only 15% of terminated trials had published final results. Endpoints were not clearly defined in 62% of trials, and only 33% explicitly reported success or failure in meeting endpoints. While 17% of all trials had positive outcomes, 48% failed, and 35% lacked sufficient data for assessment. Of completed trials 25% yielded positive and 23% negative results, while 52% were unassessable due to inadequate reporting. Terminated trials fared worse, reporting only 30% failure and 3% success rate, with 67% lacking sufficient data to evaluate outcomes. Industry-sponsored trials had slightly higher publication rates than non-industry trials (59% vs. 51%, p = 0.006), but endpoint clarity and success rates did not differ. Phase 3 trials were more likely to report both positive and negative outcomes compared to Phase 1 trials (77% vs. 23%, p < 0.00001). Furthermore, trials with positive outcomes were more likely to publish clearly stated results compared to negative trials (92% vs. 67%, p < 0.003), highlighting a persistent bias in favor of publishing successful results. Conclusions: This extensive analysis reveals critical deficiencies in the reporting of IO clinical trials, with nearly half unpublished, endpoints often undefined, and negative outcomes poorly reported. Such gaps hinder scientific progress, waste resources, and delay patient access to optimized therapies. Establishing mandatory reporting policies, ensuring endpoint clarity, and requiring publication of all outcomes, regardless of trial results, are essential for advancing IO research, improving trial efficiency, and delivering more effective treatment to patients.