Abstract OT2-21-01: A randomized, multicenter pragmatic trial comparing bone pain from a single dose of pegfilgrastim to 5 doses of daily filgrastim in breast cancer patients receiving neoadjuvant/adjuvant chemotherapy (REaCT-5G)

Abstract Background: Current guidelines recommend the use of granulocyte colony-stimulating factors (G-CSF) as primary prophylaxis to prevent febrile neutropenia (FN) associated with commonly used breast cancer chemotherapy regimens. Filgrastim (FIL) is a short-acting G-CSF injection that requires daily subcutaneous injection starting 24-72 hours after chemotherapy for 5 to 10 days. Pegfilgrastim (PEG) is a long-acting, pegylated formulation that requires a single injection 24-72 hours after chemotherapy. G-CSF causes bone pain in approximately 70% of patients, which can be severe in over 25% of cases. While registration trials for PEG showed bone pain from PEG was comparable to FIL when given for a median duration of 11 days, many oncologists are now only prescribing FIL for 5 days based on a multicenter RCT showing that 5 days of FIL is non-inferior to 7 or 10 days of FIL in terms of FN and treatment-related hospitalizations. Furthermore, the cost of 5 days of FIL ($CA 721.55 for 300 mcg dose) is half of the price of a single dose of PEG ($CA 1424.63). Therefore, if 5 days of FIL leads to significantly less bone pain, this may improve health-related quality of life (HR-QoL) for patients, improve adherence to G-CSF, and improve cost-effectiveness. Methods: Patients receiving neo-/adjuvant chemotherapy for early stage breast cancer requiring primary FN prophylaxis with G-CSF will be approached for this pragmatic, multicenter, open-label superiority RCT. Using the Rethinking Clinical Trials (REaCT) methodology that incorporates an integrated oral consent model, eligible and consented patients will be randomized to either 5 days of FIL or one day of PEG with each cycle of chemotherapy. The primary endpoint is bone pain during the first 5 days after G-CSF injection using area under the curve (AUC) of the daily pain score from days 1-5 (AUC score 0 to 40) of the Bone Pain Diary. Secondary endpoints include incidence of FN and treatment-related hospitalizations, incidence of chemotherapy delay, dose-reduction, or discontinuation, incidence of chemotherapy-related mortality, rate of G-CSF compliance, healthcare resource utilization, HR-QoL, and cost-effectiveness. Participants will also complete a Treatment Preference Questionnaire (TPQ) exploring the relative importance of different factors in deciding between PEG vs. 5 days of FIL both before randomization and at the end of the study. To achieve 80% power in an ANCOVA analysis and assuming 5% are loss to follow-up, the planned sample size is 232 patients (116 per arm). The randomization (1:1 ratio) will be stratified by treatment center (4 centers) and chemotherapy regimen (taxane-based vs. anthracycline-based in the first 4 cycles). Results: The study opened for enrollment on June 9, 2021. As of July 6, 2021, the study has opened at one site, and 13 patients have been randomized.Conclusion: This will be the first RCT using a patient-reported Bone Pain Diary that was co-developed by patient partners to measure bone pain between 5 days of FIL vs. PEG. In collaboration with patient partners, the study incorporates a tool (TPQ) that explores factors that may be important in deciding between PEG and FIL, with the aim of translating the findings of this study into real world clinical practice. Citation Format: Terry L. Ng, Monica Taljaard, Marie-France Savard, Carol Stober, Stuart Nicholls, Lisa Vandermeer, Kednapa Thavorn, Claudia Hampel, Jennifer Shamess, Natalie Mills, John F. Hilton, Mark Clemons. A randomized, multicenter pragmatic trial comparing bone pain from a single dose of pegfilgrastim to 5 doses of daily filgrastim in breast cancer patients receiving neoadjuvant/adjuvant chemotherapy (REaCT-5G) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-21-01.