Efbemalenograstim alfa not inferior to pegfilgrastim in providing neutrophil support in women with breast cancer undergoing myelotoxic chemotherapy: results of a phase 2 randomized, multicenter, open-label trial

Purpose Evaluate the safety and efficacy of efbemalenograstim alfa for neutrophil support in breast cancer patients undergoing myelosuppressive chemotherapy in a phase 2, dose-finding, open-label study (NCT01648322, ClinicalTrials.gov, 2012-07-19).Methods 232 patients received up to 4 cycles of chemotherapy, 141 patients with docetaxel + cyclophosphamide (TC) and 91 patients with docetaxel + doxorubicin + cyclophosphamide (TAC). Patients were randomized to efbemalenograstim alfa (80, 240, or 320 mu g/kg [TC]; 240 or 320 mu g/kg [TAC]) or pegfilgrastim (6 mg) on Day 2 of each cycle.Results Efbemalenograstim alfa was non-inferior to pegfilgrastim in duration of moderate and severe neutropenia (absolute neutrophil count [ANC] < 1.0 x 10(9)/L) in TAC Cycle 1 (mean [SD] of 2.1 [1.58] and 2.1 [1.46] days for 240 <mu>g/kg and 320 mu g/kg efbemalenograstim alfa, respectively, and 1.8 [1.28] days for pegfilgrastim), with a difference (95% CI) of 0.3 (-0.4, 1.1) days. ANC nadir occurred between Days 7-8 of TAC Cycle 1, with mean [SD] of 0.68 [1.064], 0.86 [1.407] and 0.78[1.283] x 10(9)/L for 240 mu g/kg, 320 mu g/kg efbemalenograstim alfa and pegfilgrastim, respectively. Time to ANC recovery post nadir (defined as an ANC > 2.0 x 10(9)/L after the expected ANC nadir) was 2.0-2.4 and 1.9 days for TAC patients treated with efbemalenograstim alfa and pegfilgrastim, respectively. No significant difference was found between any dose of efbemalenograstim alfa and pegfilgrastim in TAC Cycle 1 for incidence of moderate to severe neutropenia (76%-77% of patients) or incidence of severe neutropenia (ANC < 0.5 x 10(9)/L; 63%-72%). Efbemalenograstim alfa exhibited similar safety profile to pegfilgrastim. Febrile neutropenia occurred in 4 (1.8%) patients, 2 patients each for 320 <mu>g/kg efbemalenograstim alfa and pegfilgrastim, with no event considered related to study drug.Conclusion Efbemalenograstim alfa was comparable to pegfilgrastim in efficacy and safety.