Relationship between phase I study duration and symptom burden

Phase I clinical trials are critical to development of cancer therapeutics. Adverse events (AEs) and symptom burden contribute to early treatment withdrawal, and it is often difficult to ascertain whether these events are disease- or treatment-related. Regardless, early withdrawal may delay determination of the effectiveness of potential new therapies. We sought to characterize the reasons for early treatment termination to identify potential modifiable events.

A retrospective chart review was conducted on solid tumor patients enrolled in institutional phase I clinical trials from 2003 to 2013 through the Case Comprehensive Cancer Center.

Two hundred fifty-five patients were included in the analysis. The mean duration on study was 78.4 days (SD 63.4 days), and 23% of the patients were on study ≤ 30 days. Patients experienced an average of 25.1 AEs, of which 46.9% were non-laboratory. Constitutional symptoms (29.3%), gastrointestinal symptoms (24%), and pain (12.8%) were the most common non-laboratory AEs. Disease progression (57.6%) was the most common reason for study discontinuation, followed by adverse events (16.5%). Approximately 13% of the patients discontinued treatment for other reasons, of which 41.7% were identified as related to symptom burden on further review. Increased rates of AEs negatively correlated with duration on study (r = - 0.331; p < 0.01).

AEs may lead to early termination of trial participation and confound clinical assessment of investigational treatments. Designing interventions to reduce AE burden may extend duration on trial, affect the recommended phase II dose, and benefit the quality of life of participants on phase I trials.