Introduction:
Lipegfilgrastim is a long-acting glycopegylated granulocyte-colony stimulating factor (G-CSF) used to prevent chemotherapy-induced neutropenia (CIN) and febrile neutropenia (FN). The aim of the current study was to obtain data on the drug efficacy and safety in real-world clinical practice.

Material and methods:
This is an exploratory analysis of Polish breast cancer patients participating in a pan-European study of lipegfilgrastim in primary and secondary prophylaxis for patients receiving cytotoxic chemotherapy (Lonquex ObsErvational Cohort Study, LEOS). Patients were followed since the start of neutropenia prophylaxis until 6 to 8 weeks after the last dose of the lipegfilgrastim . The efficacy measures were chemotherapy dose reductions, omissions, delays and the proportion of the planned cumulative dose actually delivered.

Results:
A total of 45 mostly high risk of FN patients were included in the analysis. Overall, 31 of 212 chemotherapy cycles (14.6%) were delayed in 19 patients (42.2%). Cumulative dose of chemotherapy was reduced in 1.4% of the cycles in 4.4% of the patients. The mean percentage of cumulative dose planned actually administrated was 99.95% across all cycles. Only one patient had FN. There were 15 episodes of neutropenia in 3 patients (6.7%), A total of 69 adverse events were reported, which 65% were drug-related. The most common were musculoskeletal pain (17.8%) and myalgia (11.1%) Four adverse events were serious and two of them were related to lipegfilgrastim.

Conclusions:
Lipegfilgrastim proved to be effective and well-tolerated for CIN prophylaxis in patients with breast cancer receiving myelosuppressive chemotherapy in a real-life setting.