Abstract P1-13-05: Efficacy and safety of eflapegrastim confirmed in reducing severe neutropenia in breast cancer patients treated with myelosuppressive chemotherapy in the second Phase 3 randomized controlled multinational trial compared to pegfilgrastim (RECOVER trial) (2019)

Abstract Background: Eflapegrastim is a novel investigational biologic comprised of recombinant human G-CSF covalently linked to the human immunoglobulin G4FC fragment using proprietary LAPSCOVERY™ technology with potentially unique distribution to areas rich in FcRn receptors. RECOVER is the second Phase 3 study to investigate the non-inferiority (NI) of eflapegrastim to pegfilgrastim in patients receiving chemotherapy for breast cancer. The first Phase 3 study, ADVANCE, has demonstrated the non-inferiority of eflapegrastim comparing to pegfilgrastim in the duration of severe neutropenia (DSN) in breast cancer patients receiving docetaxel and cyclophosphamide (TC) and was previously published at ASCO 2018 meeting. TrialDesign: Patients with Stage I to Stage IIIA breast cancer from centers in the USA, Canada, Poland, Hungary, South Korea and India were treated on Day 1 of each of four 21-day cycles with adjuvant or neo-adjuvant TC. On Day 2 of each cycle, patients received a single subcutaneous dose of either eflapegrastim 13.2 mg/0.6 mL (equivalent to 3.6 mg G-CSF) or pegfilgrastim (6 mg) in a 1:1 ratio. Patients had CBCs drawn on Day 1 prior to chemotherapy and Days 4-15 daily or until recovery of neutropenia in Cycle 1. CBC was also collected on Days 1, 4, 7, 10 and 15 in Cycles 2-4. The primary endpoint was to demonstrate the non-inferiority of eflapegrastim comparing to pegfilgrastim as measured by the mean DSN in Cycle 1 with NI margin of &lt;0.62 day. Results: In a total of 237 intent-to-treat patients (randomized to 118 eflapegrastim; 119 pegfilgrastim), median age was 59 years (range 29 to 88 years); mean (SD) DSN was 0.31 (0.688) days for eflapegrastim and 0.39 (0.949) days for pegfilgrastim, demonstrating the non-inferiority (95% CI of ΔDSN: [-0.292, 0.129]; p&lt;0.0001). Non-inferiority of eflapegrastim for DSN was maintained across all 4 cycles. There were no statistically significant differences in secondary endpoints: time to ANC recovery, depth of ANC nadir and incidence of FN at Cycle 1. The common Grade 3/4 adverse events observed in≥5%of patients were similar across both arms and were mainly hematologic including neutropenia, lymphopenia, anemia and leukopenia. Grade 3/4 bone pain and febrile neutropenia rates were similar across both arms and were less than 5%. Conclusions: Eflapegrastim, a novel long acting G-CSF demonstrated non-inferiority to pegfilgrastim in the reduction of DSN in breast cancer patients treated with TC and has validated the results from the first Phase 3 ADVANCE study. Eflapegrastim was safe and well-tolerated with a similar safety profile to pegfilgrastim. Citation Format: Schwartzberg L, Bhat G, Mezei K, Lang I, Moon YW, Senviratne L, Chawla S, Cobb P, Yang Z. Efficacy and safety of eflapegrastim confirmed in reducing severe neutropenia in breast cancer patients treated with myelosuppressive chemotherapy in the second Phase 3 randomized controlled multinational trial compared to pegfilgrastim (RECOVER trial) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-13-05.