Safety and efficacy of same-day administration of eflapegrastim in patients with early-stage breast cancer receiving chemotherapy

BACKGROUND: Febrile neutropenia (FN) is a common complication with myelosuppressive chemotherapy regimens, significantly affecting patients with breast cancer (BC) receiving docetaxel and cyclophosphamide (TC). Treatment with granulocyte colony-stimulating factor (G-CSF) is established for prophylactic and therapeutic use to reduce risk of FN. Eflapegrastim-xnst, a novel long-acting G-CSF, has a favorable safety profile and is effective in reducing neutropenia risk in patients with early-stage BC receiving TC, when administered 24 h after chemotherapy. The benefits of eflapegrastim-xnst given same day as TC have not been evaluated in a randomized controlled trial. PATIENTS AND METHODS: This phase 1, multicenter, open-label trial evaluated efficacy and safety of eflapegrastim-xnst administered 0.5 h post-TC chemotherapy for four cycles in patients with early-stage BC. The primary end point was time to recovery of absolute neutrophil count (ANC) from nadir to ≥1.5 × 109/L in cycle 1. Secondary end points included safety, duration of severe neutropenia, incidence of FN, and neutropenic complications. RESULTS: Of 53 patients enrolled, 49 completed the study. Mean time to ANC recovery in cycle 1, the primary end point, was 1.8 days. Only 1 patient (2%) experienced an FN episode in cycle 1 (1 episode/228 cycles received [0.4%]). Incidence of severe neutropenia decreased from 42.9% (cycle 1) to 27.3% (cycle 4). Eflapegrastim-xnst was well tolerated; common treatment-emergent adverse events included fatigue, nausea, alopecia, and bone pain. CONCLUSIONS: Eflapegrastim-xnst, administered same day as TC chemotherapy was effective and well tolerated evidenced by short time to neutrophil recovery and low incidence of FN, with an adverse event profile similar to that of next-day dosing.