Biosimilar rhG-CSFs: how similar are they?

Parallelism of Chemicostructural Properties between Filgrastim Originator and Three of Its Biosimilar Drugs

The approval and granting of marketing authorization for a putative biosimilar is based on strong comparability studies with its biological reference product. This is due to the complexity of the structure and nature of the manufacturing process of biological drugs. Hence, a rigorous analytical workflow for chemical characterization and clinical trials to evaluate the efficacy and safety is required to demonstrate their high similarities to the reference drug. This work is focused on the comparison of the originator of filgrastim with three of its biosimilars by evaluating their structural similarity and biological activity. Qualiquantitative analyses were performed by MALDI-TOF/TOF-MS and RP-HPLC-UV. An innovative functional assay using zebrafish as the animal model was developed to evaluate the biological activities of the drugs. The different analyses performed in this study highlighted the structural similarity of biosimilar drugs and their originator. This result was further confirmed by a similar in vivo biological activity.

Two-Dimensional Isoelectric Focusing OFFGEL, Micro-Fluidic Lab-on-Chip Electrophoresis and FTIR for Assessment of Long-Term Stability of rhG-CSF Formulation

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been increasingly recognized from among one of the most abundant families of biosimilars. Upon long-term storage, the rhG-CSF is subject to subtle chemical modifications that rapidly occur and, in particular, produce deaminated variants with divergent charge. Indeed, changes in charge from glutamine deamination may alter the way rhG-SCF will refold and the structure of resulting molecule. To assess this charge heterogeneity, 2-D gel electrophoresis has limited application. Recent micro-fluidic- based technical advances offer a great alternative method to better control liquid volumes on a minute scale. Here, we used IEF OFFGEL-lab-on-chip electrophoresis for 2-D separation of the rhG-CSF peptides according to their isoelectric point (pI) and molecular weight (kDa). We used an rhG-CSF commercial therapeutic formulation, kept refrigerated 24 months after expiry. The samples were analyzed for particulate matter and charge variants. Subsequently, the secondary structure was assessed by FTIR spectroscopy and residual biological activity was recorded. Interestingly, we showed an additional band in the acidic gel area above and below the most intense protein band (fractions 10, 11, and 12 at 22.84s). This observation reveals the presence of the rhG-CSF variant charges without any additional high molecular weight impurity or biological activity decrease. We conclude that after two years of storage, the rhG-CSF solution maintained its native secondary structure with little -sheet deviation, as reflected in the 1622 cm-1 and 1695 cm-1. These data demonstrated that a combined strategy is a more suitable and accurate analytical assessment of the rhG-CSF and recombinant protein-based biosimilars.

Study design: two long-term observational studies of the biosimilar filgrastim Nivestim™ (Hospira filgrastim) in the treatment and prevention of chemotherapy-induced neutropenia

Background

Nivestim™ (filgrastim) is a follow-on biologic agent licensed in the EU for the treatment of neutropenia and febrile neutropenia induced by myelosuppressive chemotherapy. Nivestim™ has been studied in phase 2 and 3 clinical trials where its efficacy and safety was found to be similar to its reference product, Neupogen^®. Follow-on biologics continue to be scrutinised for safety. We present a design for two observational phase IV studies that are evaluating the safety profile of Nivestim™ for the prevention and treatment of febrile neutropenia (FN) in patients treated with cytotoxic chemotherapy in general clinical practice.

Methods/Design

The NEXT (Tolérance de Nivestim chez les patiEnts traités par une chimiothérapie anticancéreuse cytotoXique en praTique courante) and VENICE (VErträglichkeit von NIvestim unter zytotoxischer Chemotherapie in der Behandlung malinger Erkrankungen) trials are multicentre, prospective, longitudinal, observational studies evaluating the safety profile of Nivestim™ in 'real-world’ clinical practice. Inclusion criteria include patients undergoing cytotoxic chemotherapy for malignancy and receiving Nivestim as primary or secondary prophylaxis (NEXT and VENICE), or as treatment for ongoing FN (NEXT only). In accordance with European Union pharmacovigilance guidelines, the primary objective is to evaluate the safety of Nivestim™ by gathering data on adverse events in all system organ classes. Secondary objectives include obtaining information on patient characteristics, efficacy of Nivestim™ therapy (including chemotherapy dose intensity), patterns of use of Nivestim™, and physician knowledge regarding filgrastim prescription and the reasons for choosing Nivestim™. Data will be gathered at three visits: 1. At the initial inclusion visit, 2. At a 1-month follow-up visit, and 3. At the end of chemotherapy.

Recruitment for VENICE commenced in July 2011 and in November 2011 for NEXT. VENICE completed recruitment in July 2013 with 407 patients, and NEXT in September 2013 with 2123 patients. Last patient, last visit for each study will be December 2013 and March 2014 respectively.

Discussion

The NEXT and VENICE studies will provide long-term safety, efficacy and practice pattern data in patients receiving Nivestim™ to support myelosuppressive chemotherapy in real world clinical practice. These data will improve our understanding of the performance of Nivestim™ in patients encountered in the general patient population.

Trial registration

NEXT NCT01574235, VENICE NCT01627990

Simplified large-scale refolding, purification, and characterization of recombinant human granulocyte-colony stimulating factor in Escherichia coli

Granulocyte-colony stimulating factor (G-CSF) is a pleiotropic cytokine that stimulates the development of committed hematopoietic progenitor cells and enhances the functional activity of mature cells. Here, we report a simplified method for fed-batch culture as well as the purification of recombinant human (rh) G-CSF. The new system for rhG-CSF purification was performed using not only temperature shift strategy without isopropyl-l-thio-β-d-galactoside (IPTG) induction but also the purification method by a single step of prep-HPLC after the pH precipitation of the refolded samples. Through these processes, the final cell density and overall yield of homogenous rhG-CSF were obtained 42.8 g as dry cell weights, 1.75 g as purified active proteins, from 1 L culture broth, respectively. The purity of rhG-CSF was finally 99% since the isoforms of rhG-CSF could be separated through the prep-HPLC step. The result of biological activity indicated that purified rhG-CSF has a similar profile to the World Health Organization (WHO) 2^nd International Standard for G-CSF. Taken together, our results demonstrate that the simple purification through a single step of prep-HPLC may be valuable for the industrial-scale production of biologically active proteins.