A prospective cohort study to evaluate the incidence of febrile neutropenia in patients receiving pegfilgrastim on-body injector versus other options for prophylaxis of febrile neutropenia: breast cancer subgroup analysis.

BACKGROUND: Breast cancer chemotherapy often carries a high risk of febrile neutropenia (FN); guidelines recommend prophylaxis with granulocyte colony-stimulating factor (G-CSF), such as pegfilgrastim. Neulasta® Onpro® on-body injector (OBI) is a delivery device administering pegfilgrastim approximately 27 h after application. METHODS: This prospective study examined patients with breast cancer who received chemotherapy with a high risk of FN, receiving OBI ("OBI") or other options (other G-CSF or none; "other"). The primary endpoint was FN incidence; secondary endpoints included chemotherapy delivery, adherence (G-CSF in all cycles), compliance (G-CSF day after chemotherapy), and FN incidence in patients receiving curative or palliative treatment. RESULTS: A total of 1776 patients with breast cancer were enrolled (OBI, n = 1196; other, n = 580). Across all cycles, FN incidence was lower for OBI (4.4% [95% CI, 3.3-5.6%]) than other (7.4% [5.3-9.6%]). For curative treatment, the FN incidence across all cycles was lower for OBI (4.6% [3.4-5.8%]) than for other (7.1% [5.0-9.3%]). For palliative treatment (OBI, n = 33; other, n = 20), 3 patients (15%) in the other and none in the OBI group had FN. After adjusting for baseline covariates, FN incidence remained lower for OBI (4.6% [3.5-6.1%]) versus other (7.8% [5.7-10.5%]). Adherence was higher for OBI (93.8%) than for other G-CSF (69.8%), as was compliance (90.5 and 53.2%, respectively). Chemotherapy dose delays/reductions were similar for OBI (4.7%/32.3%, respectively) and other (4.7%/30.0%) groups. CONCLUSION: Pegfilgrastim OBI was associated with a lower FN incidence in patients with breast cancer compared to other options for FN prophylaxis. TRIAL REGISTRATION: www. CLINICALTRIALS: gov , NCT02178475, registered 30 June, 2014.