Xie J, et al. - In China’s registration trial (CFDA: 2006L01305), Researchers explored the advantages with prophylactic PEG-rhG-CSF(PEG-modification recombinant human granulocyte colony stimulating factor) vs rhG-CSF (Recombinant human granulocyte colony stimulating factor) in breast cancer patients receiving multiple cycles of myelosuppressive chemotherapy. They recognized PEG-rhG-CSF as a more convenient and safe formulation and a more effective prophylactic measure for these patients.

Methods

• Researchers performed this open-label, randomized, multicenter phase 3 study randomizing breast cancer patients (n = 569) to receive PEG-rhG-CSF 100 μg/kg, PEG-rhG-CSF 6 mg, or rhG-CSF 5 µg/kg/d after chemotherapy.
• The incidence and duration of grade 3/4 neutropenia during cycle 1 were assessed as the primary endpoints.
• For this study, secondary endpoints included the incidence and duration of grade 3/4 neutropenia during cycles 2–4, the incidence of febrile neutropenia, and the safety.

Results

• In terms of incidence or duration of grade 3/4 neutropenia, a once-per-cycle PEG-rhG-CSF at either 100 μg/kg or 6 mg was not different from daily injections of rhG-CSF.
• Interestingly, there appeared a substantial difference during cycle 2, and the difference became bigger over cycles 3–4, reaching a statistical significance at cycle 4 in either incidence (P=0.0309) or duration (P=0.0289) favoring PEG-rhG-CSF.
• Researchers noticed a significant trend toward a reduced incidence of all-grade adverse events at 129 (68.98%), 142 (75.53%), and 160 (82.47%) in the PEG-rhG-CSF 100 μg/kg and 6 mg and rhG-CSF groups, respectively (P=0.0085).
• The corresponding incidence was 2/187 (1.07%), 1/188 (0.53%), and 8/194 (4.12%), respectively, for grade 3/4 drug-related adverse events (P=0.0477).
• In addition, PFS in metastatic patients preferred PEG-rhG-CSF to rhG-CSF despite no significance observed by Kaplan–Meier analysis (n = 49, P=0.153).