Balugrastim: A long-acting, once-per-cycle, recombinant human albumin-fusion filgrastim.

Abstract

e13551 Background: Balugrastim is a once-per-cycle fixed-dose genetic fusion protein composed of human serum albumin (HSA) and granulocyte colony-stimulating factor (G-CSF) in development for prevention of severe neutropenia in cancer patients receiving chemotherapy. Albumin fusion is a clinically validated technology that extends product half-life, allowing for infrequent dosing, better tolerability, lower cost, and improves drug design, potentially lowering immunogenicity risk. Here, we describe the technology used to produce balugrastim and summarize preclinical findings compared with pegfilgrastim (Neulasta). Methods: Design and production of balugrastim was described previously (Halpern et al. Pharmaceut Res 2002;19:1720−1729). Biologic activity of balugrastim was assessed in an NFS-60 cell line proliferation assay vs filgrastim and pegfilgrastim. PK and PD properties were studied in healthy and neutropenic animal models. Results: Albumin fusion produces a long-acting G-CSF with comparable pharmacologic properties to pegfilgrastim. In vitro, balugrastim had binding affinity and cell proliferation activity comparable to pegfilgrastim, and both were lower than non-PEGylated filgrastim on a molar basis. Overall increases in leukocytes, neutrophilic granulocytes, and monocytes were dose dependent and consistent with the effects expected for a long-acting G-CSF with some variation based on the specific animal model used. A single balugrastim dose in BDF1 mice elicited a dose-dependent increase in peripheral granulocytes and mobilized hematopoietic progenitor cells. In cynomolgus monkeys, balugrastim caused an increase in peripheral neutrophils similar to pegfilgrastim, with higher responses after 2nd, 3rd, and 4th doses. In mice, balugrastim had shorter terminal half-life and mean residence time, and faster clearance than pegfilgrastim. In monkeys, terminal half-life of balugrastim was slightly longer than pegfilgrastim. Conclusions: An albumin fusion technology platform was used to produce balugrastim – a novel, biologically active albumin G-CSF fusion protein with greater structural homogeneity and comparable pharmacologic properties to conventionally PEGylated G-CSFs.