Safety profile of EP2006 biosimilar filgrastim: A combined analysis of two independent phase III studies.

Abstract

e21701 Background: The biosimilar filgrastim Zarzio (EP2006) was approved in Europe in 2009 and in 2015 became the first biosimilar approved by the FDA for use in the USA, marketed as Zarxio. Two phase III registration studies were performed to confirm the efficacy and safety of biosimilar filgrastim in women with breast cancer receiving myelotoxic chemotherapy. Methods: Data were combined from the studies to evaluate safety. Study 1 (US registration trial) was a randomized, double-blind comparative study of biosimilar and reference filgrastim (Neupogen, Amgen) in women ≥18 years with breast cancer receiving (neo)adjuvant treatment for 6 consecutive cycles with TAC (docetaxel 75 mg/m2, doxorubicin 50 mg/m2, and cyclophosphamide 500 mg/m2). Study 2 (EU registration trial) was a single-arm, open-label study of biosimilar filgrastim in women ≥18 years with breast cancer receiving doxorubicin 60 mg/m2 and docetaxel 75 mg/m2 for 4 consecutive cycles. In/exclusion criteria and statistical definitions used for both studies were similar. Data of the patients treated with biosimilar filgrastim only were combined for Cycles 1-4. Results: A total of 277 patients (mean±SD age: 51.1±10.8 years) received biosimilar filgrastim (5 μg/kg bw/day sc). Treatment-emergent adverse events (TEAEs) were consistent with the known safety profile of filgrastim. The most frequently reported filgrastim-related TEAEs were musculoskeletal/connective tissue disorders (9.4%), including bone pain (5.8%) (Cycle 1). No neutralizing anti-filgrastim antibodies were detected. Mean±SD duration of severe neutropenia was 1.04±1.51 days in Cycle 1. Mean±SD depth of absolute neutrophil count nadir in Cycle 1 was 0.94±1.40 x 109/L. Conclusions: Safety data for biosimilar filgrastim EP2006 is consistent with reference filgrastim in women with breast cancer undergoing myelotoxic chemotherapy. Clinical trial information: NCT01519700. [Table: see text]