Efficacy and safety of mecapegfilgrastim for prophylaxis of chemotherapy-induced neutropenia in patients with breast cancer: a randomized, multicenter, active-controlled phase III trial

Background: Neutropenia is a common complication from chemotherapy. Mecapegfilgramtim (code name HHPG-19K), a long-acting recombinant human granulocyte colony-stimulating factor (rhG-CSF), has been developed. This study was to evaluate the efficacy and safety of mecapegfilgrastim for reducing neutropenia compared with filgrastim. Methods: This was a randomized, controlled non-inferiority study. A total of 339 breast cancer patients who were eligible for (neo) adjuvant chemotherapy were randomized assigned into three groups to receive mecapegfilgrastim 100 mu g/kg, mecapegfilgrastim fixed dose of 6 mg or filgrastim 5 mu g/kg/day in the first cycle of chemotherapy. The primary endpoint was the duration of grade >= 3 neutropenia in cycle 1. The secondary endpoints included the duration of grade >= 3 neutropenia in cycles 2-4, incidence of grade >= 3 neutropenia, and febrile neutropenia (FN). The safety profile was also evaluated. Results: The mean duration of grade >= 3 neutropenia was 1.06 [95% confidence interval (CI): 0.65, 1.26] days in mecapegfilgrastim 100 mu g/kg group, 1.23 (95% CI: 0.84, 1.88) days in mecapegfilgrastim 6 mg group, and 2.06 (95% CI: 1.66, 2.46) days in the filgrastim group. The mean difference between mecapegfilgrastim 100 mu g/kg and filgrastim was -1.00 (95% CI: -1.52, -0.48), the mean difference between mecapegfilgrastim 6 mg and filgrastim was -0.83 (95% CI: -1.36, -0.30). The upper bounds of 95% CI for the difference between mecapegfilgrastim and filgrastim were all <1 day (the predefined non-inferiority margin). For the incidence of grade >= 3 and grade 4 neutropenia, the mean duration of grade 4 neutropenia, mecapegfilgrastim showed better performance compared with filgrastim. For the incidence of FN, there was no difference between patients treated with mecapegfilgrastim and filgrastim. For safety profile, mecapegfilgrastim of two doses groups were all well-tolerated. Fixed 6 mg dose of mecapegfilgrastim exhibited comparable efficacy and safety in comparison with 100 mu g/kg during 4 cycles. Conclusions: Long-acting mecapegfilgrastim (100 mu g/kg and fixed 6 mg) is very effective and well tolerated when administered in the primary prophylaxis of chemotherapy induced neutropenia and in consecutive-cycle treatment. In some clinical parameters, mecafilgrastim is non-inferior and even superior to filgrastim. The fixed 6 mg-dose regimen showed similar efficacy and safety profile compared with 100 mu g/kg regimen, and would be the preference in clinical practice, due to the convenient once-per-cycle administration and high-degree treatment compliance for the patients. This study provided new evidence for the novel long-acting rhG-CSF, mecapegfilgrastim, which would be a new alternative for clinical practice for prophylaxis of chemotherapy induced neutropenia.