A multi-center pragmatic, randomized, feasibility trial comparing standard of care schedules of filgrastim administration for primary febrile neutropenia prophylaxis in early-stage breast cancer.

Introduction: The most effective duration of filgrastim as primary febrile neutropenia (FN) prophylaxis in early breast cancer (EBC) patients is unknown. Despite significant differences in cost and toxicity, no prospective trial has been performed to optimize practice. We assessed the feasibility of using a novel pragmatic trial model to compare the most commonly used schedules of filgrastim.

Methods: Early breast cancer patients receiving chemotherapy were randomized to 5, 7, or 10 days of filgrastim as primary FN prophylaxis. The trial methodology integrated broad eligibility criteria, simply defined endpoints, an integrated consent model incorporating oral consent, and web-based randomization in the clinic. Feasibility was reflected through a combination of primary endpoints including patient and physician engagement (if > 50% of appropriate patients approached agree to participate, and if > 50% of physicians approached patients for the study). Secondary endpoints included the first occurrence rates of FN, treatment-related hospital admission, or chemotherapy dose reductions/delays/discontinuation.

Results: From May 2015 to August 2016, 142/149 (95.3%) patients approached agreed to participate and were randomized. Seventeen of 24 (70.8%) medical oncologists approached and randomized patients. The 142 patients received a total of 495 cycles of chemotherapy. Aggregate incidences of a first event by patient were FN (8/142, 5.6%), treatment-related hospitalization (6/142, 4.2%), chemotherapy discontinuation (7/142, 4.9%), chemotherapy delays (5/142, 3.5%), and chemotherapy dose reduction (18/142, 12.7%). Overall, 31.7% (45/142) of patients and 9.0% (45/495) of chemotherapy cycles were associated with one of these first events.

Conclusion: This study met its feasibility endpoints. This novel pragmatic trial approach offers a means of comparing standard of care treatments in a practical and cost-effective manner. The trial will now be expanded to compare rates of FN between the three filgrastim schedules.

Trial Registration: ClinicalTrials.gov: NCT02428114.