Pegfilgrastim administration after 24 or 72 or 96 h to allow dose-dense anthracycline- and taxane-based chemotherapy in breast cancer patients: a single-center experience within the GIM2 randomized phase III trial.

Purpose: To evaluate the safest timing of pegfilgrastim administration in dose-dense anthracycline- and taxane-based chemotherapy, three different cohorts of patients enrolled in the Gruppo Italiano Mammella (GIM) 2 study and treated at the coordinating center received pegfilgrastim 24 h (cohort A) or 72 h (cohort B) or 96 h (cohort C) after chemotherapy.

Methods: A total of 41 patients were included. The safety of pegfilgrastim administration in terms of occurrence of early and late leukocytosis and the behavior of white blood cells (WBC) counts in the three cohorts across all chemotherapy cycles were evaluated. Anthracycline and taxane cycles were analyzed separately.

Results: The occurrence of early leukocytosis was a more common event in patients in cohort A in both anthracycline and taxane cycles (75 and 66.7%) as compared to cohort B (50 and 60%) and cohort C (66.7 and 33.3%). More patients in cohort C developed late leukocytosis in both anthracycline and taxane cycles (50 and 100%) as compared to cohort A (0 and 66.7%) and cohort B (35.7 and 86.7%). Patients in cohort A experienced the highest median value of WBC count 24 h after pegfilgrastim administration in both anthracycline and taxane cycles (61.2 × 10(3)/μl and 67.8 × 10(3)/μl). Patients in cohort C experienced the highest median value of WBC count at day 13 in both anthracycline and taxane cycles (19.4 × 10(3)/μl and 24.2 × 10(3)/μl).

Conclusions: For the prevention of leukocytosis, the safest timing of pegfilgrastim administration based on WBC count in dose-dense anthracycline- and taxane-based regimens seems to be 72 h after chemotherapy.

Trial Registration: This study is registered with https://clinicaltrials.gov/ct2/show/NCT00433420.