PURPOSE Pegylated granulocyte-colony-stimulating factor (G-CSF) is frequently used to prevent febrile neutropenia (FN) in patients undergoing chemotherapy with a high risk of myelosuppression. This phase II/III study was conducted to determine the adequate dose of pegteograstim, a new formulation of pegylated G-CSF, and to evaluate the efficacy and safety of pegteograstim compared to pegfilgrastim.

METHODS In the phase II part, 60 breast cancer patients who were undergoing DA (docetaxel and doxorubicin) or TAC (docetaxel, doxorubicin, and cyclophosphamide) chemotherapy were randomly selected to receive a single subcutaneous injection of 3.6 or 6.0 mg pegteograstim on day 2 of each chemotherapy cycle. The phase III part was seamlessly started to compare the dose of pegteograstim at selected in phase II with 6.0 mg pegfilgrastim in 117 breast cancer patients. The primary endpoint of both the phase II and III parts was the duration of grade 4 neutropenia in the chemotherapy cycle 1.

RESULTS The mean duration of grade 4 neutropenia for the 3.6 mg pegteograstim (n = 33) was similar to that for the 6.0 mg pegteograstim (n = 26) (1.97 ± 1.79 days vs. 1.54 ± 0.95 days, p = 0.33). The 6.0 mg pegteograstim was selected to be compared with the 6.0 mg pegfilgrastim in the phase III part. In the phase III part, the primary analysis revealed that the efficacy of pegteograstim (n = 56) was non-inferior to that of pegfilgrastim (n = 59) [duration of grade 4 neutropenia, 1.64 ± 1.18 days vs. 1.80 ± 1.05 days; difference, -0.15 ± 1.11 (p = 0.36, 97.5 % confidence intervals = 0.57 and 0.26)]. The time to the absolute neutrophil count (ANC) recovery of pegteograstim (≥2000/μL) was significantly shorter than that of pegfilgrastim (8.85 ± 1.45 days vs. 9.83 ± 1.20 days, p < 0.0001). Other secondary endpoints showed no significant difference between the two groups. The safety profiles of the two groups did not differ significantly.

CONCLUSIONS Pegteograstim was shown to be as effective as pegfilgrastim in the reduction of chemotherapy-induced neutropenia in the breast cancer patients who were undergoing chemotherapy with a high risk of myelosuppression.