Final Results of a Placebo-Controlled Study of Filgrastim in Small-Cell Lung Cancer: Exploration of Risk Factors for Febrile Neutropenia

A phase III study of filgrastim as an adjunct to combination chemotherapy in previously untreated patients with limited- or extensive-stage small-cell lung cancer was conducted. This final analysis explores baseline factors that might predict febrile neutropenia and also reports the results of 463 open-label filgrastim cycles that were delivered after patients' initial episode of the primary endpoint, ie, febrile neutropenia.A total of 244 patients were randomized to receive placebo or filgrastim in/= 6 cycles of chemotherapy (cyclophosphamide/doxorubicin/etoposide).The cumulative percent of patients receiving filgrastim who experienced febrile neutropenia was approximately 50% lower than those given placebo (38% vs. 74%, respectively; P0.0001). Significant treatment-related reductions were also seen in the incidence and duration of grade 4 neutropenia. Cycle 1 displayed the highest incidence of neutropenia with or without fever and the longest duration of neutropenia relative to later cycles. Patients crossing over to open-label filgrastim from their blinded treatment assignment displayed event rates similar to those in the blinded filgrastim group. Patients who experienced febrile neutropenia in cycle 1 were at a significantly higher risk for subsequent events compared with those who were event-free in cycle 1. Women displayed a higher risk for febrile neutropenia than men, but no other baseline risk factors were detected.Given the high rate of febrile neutropenia in cycle 1 and the higher risk for subsequent events in patients with a cycle 1 event, we conclude that growth factor administration starting in cycle 1 should be considered for patients receiving moderately to highly myelosuppressive chemotherapy regimens.