Secondary Endpoint Utilization and Publication Rate among Phase III Oncology Trials

Area of Science:

• Oncology Clinical Trials
• Biostatistics
• Scientific Publication

Background:

• Secondary endpoints (SEPs) are vital for interpreting clinical trial results but their characteristics and publication patterns remain unclear.
• Understanding SEP utilization and publication is crucial for assessing the completeness of trial data.

Purpose of the Study:

• To empirically characterize the scope and publication rates of SEPs in late-phase oncology trials.
• To identify factors associated with SEP publication rates.

Main Methods:

• Analysis of randomized, published phase III oncology trials and their associated ClinicalTrials.gov entries and protocols.
• Logistic regression to evaluate associations between trial characteristics and SEP publication rates.
• Screening of 280 trials with 244,576 patients and 2,562 SEPs.

Main Results:

• Only 22% of trials showed consistent SEP listing between ClinicalTrials.gov and protocols.
• The number of SEPs per trial increased over time, with industry-sponsored trials having more SEPs.
• Overall, 69% of SEPs were published, with significant variation by category.
• Patient-reported outcomes (63%) and translational correlatives (44%) had lower publication rates.
• Trials with more SEPs were associated with lower overall SEP publication rates.

Conclusions:

• SEP publication rates in late-phase oncology trials are highly variable, depending on the endpoint type.
• Underpublication of patient-burdening SEPs like patient-reported outcomes and translational correlatives was observed.
• Trialists should consider the relevance and feasibility of SEPs during trial design to ensure transparency and minimize patient burden.