Introduction: The pivotal trials of pegfilgrastim and filgrastim demonstrated their value as primary protection if initiated 24 hours after chemotherapy (CT) administration from CT cycle 1. Current clinical use patterns for pegfilgrastim and filgrastim may differ and may include primary protection in cycle (C) 1 or secondary protection in later cycles. Additionally, the initiation day within a CT cycle could be early (primary protection), late (reactive use), or for treatment of established neutropenia or febrile neutropenia (FN). A retrospective chart review is underway to determine current use patterns and applications of once-per-cycle pegfilgrastim (approved in 2002) and daily filgrastim.
Methods: Patient (pt) medical records are being retrospectively collected from 100 randomly selected US private oncology practices. Eligible pts are ≥18 years of age, diagnosed with non-Hodgkin’s lymphoma (NHL), Hodgkin’s disease (HD), lung (LC), ovarian (OC), colorectal (CRC) or breast (BC) cancers, and have received ≥1 CT cycle. This planned interim analysis evaluates pegfilgrastim and filgrastim utilization in cancer pts receiving CT in 2003.
Results: Medical records of 624 pts from 34 sites receiving pegfilgrastim or filgrastim have been abstracted to date. Pegfilgrastim was initiated in 351(56%) pts and filgrastim was initiated in 273 (44%) pts. Of the 624 pts, 120 (19%) received both pegfilgrastim and filgrastim (no pt used both products in the same cycle). Of these, 94 (78%) received pegfilgrastim after initially receiving filgrastim while 26 (22%) received filgrastim after initially receiving pegfilgrastim.
The distribution of tumor types for the 325 pts receiving only pegfilgrastim was BC 43%; LC 24%; NHL 20%; HD 5%; OC 5%; CRC 3%. The planned CT cycle length (days) for pts receiving pegfilgrastim was: Q21 (56%), Q14 (11%), Q28 (11%), Q7 (2%). In C1, 58% of pts received pegfilgrastim; in C2, 86% received pegfilgrastim. In C1, pegfilgrastim was administered ≤3 days after CT in 76% (142/187) of pts and in 83% (200/240) of pts in C2. C1 use of pegfilgrastim was 68% for lymphoma and 54% for solid tumor pts.
The distribution of tumor types for the 179 pts receiving only filgrastim was BC 46%; LC 24%; CRC 12%; NHL 9%; HD 6%; OC 4%. The planned CT cycle length (days) for pts receiving filgrastim was: Q21 (35%), Q28 (17%), Q14 (15%), Q7 (12%). In C1, 62% of pts received filgrastim; in C2, 83% received filgrastim. In C1, filgrastim was administered ≤3 days after CT in 31% (34/111) of pts increasing to 48% (52/108) of pts in C2. Filgrastim was initiated ≥10 days after CT in C1 in 48% (53/111) of pts and in 26% of pts (28/108) in C2. C1 use of filgrastim was 58% for lymphoma and 63% for solid tumor pts.
Conclusions: From this interim analysis, most pts initiated pegfilgrastim in C1 and early within a cycle, suggesting primary protection. Most pts initiated filgrastim also in C1, however the day of initiation is much later, suggesting reactive use or treatment of established neutropenia or FN. Future analyses will evaluate factors associated with use (or non-use) of pegfilgrastim and filgrastim including baseline and treatment characteristics.