Outcomes in Patients With Curative Malignancies Receiving Filgrastim as Primary Prophylaxis.

Background: Granulocyte colony-stimulating factor prophylaxis has been shown to reduce the risk and duration of chemotherapy-induced neutropenia and febrile neutropenia and is recommended for at-risk patients receiving chemotherapy. Within the South Texas Veterans Health Care System, daily filgrastim injections remain the preferred formulation of granulocyte colony-stimulating factor for primary prophylaxis of febrile neutropenia.

Methods: This retrospective, single-center cohort study included 59 patients who received daily filgrastim as primary prophylaxis with a curative cancer diagnosis and a chemotherapy regimen at the South Texas Veterans Health Care System from September 1, 2015 to September 24, 2020. Patients had either a high risk for febrile neutropenia or a chemotherapy regimen with an intermediate risk for febrile neutropenia and additional risk factors. The primary outcome was the incidence of neutropenia/febrile neutropenia leading to treatment delays. Secondary outcomes included chemotherapy dose decreases or discontinuations, hospitalizations, days of hospitalization, infections, extended duration of filgrastim, and transitions to pegfilgrastim due to neutropenia/febrile neutropenia.

Results: Patients received a median (IQR) of 7 (5-10) doses of filgrastim for primary prophylaxis. Overall, 10 patients (17%) experienced treatment delays due to neutropenia/febrile neutropenia. Fifteen patients (25%) were hospitalized with a median (IQR) length of stay of 5 (4-7) days, 9 patients (15%) had documented infections, and 2 patients (3%) required a chemotherapy dose reduction. Additionally, 9 patients (15%) required an additional median (IQR) of 2 (2-5) doses of filgrastim, and 9 (15%) patients were transitioned to pegfilgrastim.

Conclusions: These results suggest that additional measures such as tracking postnadir absolute neutrophil counts should be performed to ensure patients receive an appropriate number of filgrastim doses to prevent complications associated with neutropenia/febrile neutropenia.