Temporal trends in oncology clinical trial complexity and duration: A retrospective analysis of 5,261 industry-sponsored trials.

11018 Background: Clinical trial complexity has been cited as a contributor to rising drug development costs and increasing trial duration. We aimed to quantify multidimensional oncology trial complexity and describe temporal trends. Methods: We conducted a retrospective analysis of industry-sponsored interventional drug and biological oncology trials from the Aggregate Analysis of ClinicalTrials.gov (AACT) database, restricted to concluded trials initiated 2007-2017 for post-FDAAA reporting consistency and adequate follow-up. Five complexity dimensions were derived using principal component analysis: protocol (eligibility criteria, arms, outcomes), operational (sites, countries, planned enrollment), disease (MeSH breadth), intervention (modality count), and governance (team structure). Temporal trends were analyzed across completed trials only; Pearson correlations between dimensions and duration/early termination were calculated across all concluded trials. Trends were estimated using linear regression on yearly medians stratified by phase. Results: Among 6,752 concluded oncology trials (78% completion rate), temporal trends were analyzed in the 5,261 completed trials. Protocol complexity significantly increased (+0.083 SD/year), driven by total eligibility criteria (+0.56/year), secondary outcomes (+0.35/year), and exclusion criteria (+0.35/year). Operational complexity showed a significant increasing trend (+0.014 SD/year), with facilities increasing +0.51/year. Overall trial duration significantly increased (+16.7 days/year), with Phase 1 trials increasing +18.2 days/year and Phase 2 trials +18.4 days/year, while Phase 3 trials showed a non-significant trend (+20.7 days/year). Across all trials, protocol complexity was weakly correlated with early termination (r=0.03) and duration (r=0.14). Operational complexity showed the strongest correlation with duration (r=0.36). Conclusions: Among concluded oncology trials, protocol and operational complexity are significantly increasing, particularly eligibility criteria burden, endpoint multiplicity, and study scale. Trial duration is significantly increasing for early-phase trials, driven primarily by operational complexity. Operational and protocol trends in oncology trials. Metric (median) 2007 Value 2017 Value Slope/Year P-value Total I/E Criteria 15 22 +0.56 <0.001 Secondary Outcomes 4 7 +0.35 <0.001 Exclusion Criteria 8 12 +0.35 <0.001 Inclusion Criteria 6 9 +0.22 <0.001 Total Outcomes 8 11 +0.30 <0.001 Number of Sites 6 12 +0.51 <0.001 Phase 1 Duration (days) 1080.5 1220 +18.2 0.010 Phase 2 Duration (days) 1249 1347 +18.4 0.028 Phase 3 Duration (days) 1583 1673 +20.7 0.214 Overall Duration (days) 1247 1378 +16.7 0.006 Observed medians are reported for 2007 and 2017. Slopes and p-values were derived from linear regression on yearly medians.