Characterization and outcomes of patients enrolled to multiple phase I cancer trials.

PURPOSE: Some patients who participate in early phase cancer trials enroll to more than one trial. Whether these patients have different characteristics or outcomes than patients who enroll to a single phase I trial is unknown.

METHODS: The study included all patients who participated in the solid tumor drug development program of the Princess Margaret Cancer Centre, a specialized academic cancer center, from July 2014 to January 2017. Patients sequentially enrolled to multiple phase I trials were compared to those enrolled in a single trial according to demographics, clinical characteristics, reported toxicities and prognosis.

RESULTS: The study cohort included 328 patients, including 61 (19%) enrolled to multiple phase I trials and 267 (81%) enrolled to a single phase I trial. Demographics, comorbidities, performance status, cancer site and time between initial diagnosis and initial enrollment to the phase I program were comparable between both groups. Patients enrolled to multiple phase I trials received more previous non-trial treatment lines (median 3 versus 2, p < 0.001) and had a higher average response rate on phase I trials (18% versus 10%, p = 0.03). Toxicity data, including number of any adverse events (AEs), grade 3/4 AEs, serious AEs and dose-limiting toxicities were comparable between both groups. Time to disease progression and time to last documented follow-up were also comparable between both groups.

CONCLUSIONS: Patients enrolled to multiple phase I trials and those enrolled to a single trial had similar toxicity and prognostic profiles. These patients do not introduce bias into early-phase cancer trials results.