An observational, prospective, open label, multicenter study to evaluate the safety and effectiveness of pegfilgrastim as secondary prophylaxis to decrease the incidence of febrile neutropenia in Korean female patients with breast cancer.

Purpose: Pegfilgrastim is a widely used long-acting granulocyte colony-stimulating factor (G-CSF) that prevents febrile neutropenia (FN) in patients with breast cancer receiving chemotherapy. This study aimed to evaluate the incidence of chemotherapy-related FN events and other adverse events (AEs) during chemotherapy in Korean patients with breast cancer treated with pegfilgrastim as secondary prophylactic support.

Materials And Methods: This was a multicenter, open-label, prospective, observational study. A total of 1255 patients were enrolled from 43 institutions. The incidence of FN was evaluated as the primary endpoint. The secondary endpoints included (1) incidence of bone pain, (2) proportion of patients with a relative dose intensity (RDI) of ≥85%, and (3) proportion of patients with AE.

Results: Pegfilgrastim administration reduced FN by 11.8-1.6%. The highest incidence of bone pain was observed at the time point of the 1st day after the administration and mild bone pain was the most common of all bone pain severity. The mean RDI was 98.5 ± 7.3%, and the proportion of the patients with and RDI≥85% was 96.9% (1169/1233). AEs were reported in 52.6% of the patients, and serious drug reactions occurred in only 0.7%.

Conclusion: The use of pegfilgrastim as secondary prophylaxis was effective and safe for preventing FN in patients with breast cancer who were treated with chemotherapy.