Comparison of the pharmacodynamic profiles of a biosimilar filgrastim and Amgen filgrastim: results from a randomized, phase I trial

Effectiveness and Safety of Filgrastim (Neupogen™) versus Filgrastim-aafi (Nivestim™) in Primary Prophylaxis of Chemotherapy-Induced Febrile Neutropenia: An Observational Cohort Study

BACKGROUND

Despite the demonstrated efficacy and safety of biosimilar filgrastim-aafi (Nivestim™), few studies have compared its use in real-life clinical practice to the originator filgrastim (Neupogen™).

OBJECTIVES

This study aimed to compare the effectiveness and safety of filgrastim and filgrastim-aafi for the primary prophylaxis of chemotherapy induced-febrile neutropenia in the real-life setting.

PATIENTS AND METHODS

A retrospective cohort study included all adult cancer patients at the King Hussein Cancer Centre requiring primary prophylaxis for chemotherapy-induced febrile neutropenia between 2014 and 2016. Two cohorts were selected: patients who received filgrastim and those who received filgrastim-aafi. The primary endpoint was the incidence of febrile neutropenia; the secondary endpoints were the incidence of adverse drug reactions (ADRs), hospital admissions due to febrile neutropenia, and the mean length of hospitalization. Chi-squared tests were performed to evaluate differences between groups. Logistic regression was conducted to adjust for confounding factors.

RESULTS

A total of 268 patients were identified, with 88 in the filgrastim cohort and 180 in the filgrastim-aafi cohort; 64%were females. The mean age was 47 (±15) years. The incidence of febrile neutropenia was 21.6% in the filgrastim cohort and 15% in the filgrastim-aafi cohort (P = 0.179). No statistically significant differences were detected in the incidence of hospital admission (P = 0.551) or ADRs (P = 0.623) between the two cohorts. Upon adjusting for the confounding factors, results remained statistically insignificant.

CONCLUSION

Filgrastim and filgrastim-aafi had comparable effectiveness and safety as primary prophylaxis for chemotherapy-induced febrile neutropenia. More extensive prospective studies with additional insight on the cost implications are required.

Mobilization of Hematopoietic Stem Cells into Peripheral Blood for Autologous Transplantation Seems Less Efficacious in Poor Mobilizers with the Use of a Biosimilar of Filgrastim and Plerixafor: A Retrospective Comparative Analysis

Introduction

Biosimilars of granulocyte colony-stimulating factors (G-CSF) have shown similar efficacy to originator filgrastim (Neupogen® [NEU]; Amgen Inc.) as prophylaxis in neutropenia and in the mobilization of stem cells in patients receiving combination chemotherapy with G-CSF.

Methods

This was a retrospective study in which the characteristics of stem cell mobilization treated with a G-CSF alone were compared in 216 patients and 56 donors. The two G-CSF compared were NEU and the biosimilar filgrastim Zarzio® (Sandoz GmbH) (referred to hereafter as BIO). Primary objectives were mobilization rate (minimum of 10 × 10³/ml CD34+ on day 4 of treatment [day +4]) and use of the immunostimulant plerixafor (PLEX) in each group.

Results

The general characteristics of the patients receiving NEU (n = 138) and those receiving BIO (n = 78) did not differ significantly. PLEX was used in 24% of BIO patients and in 25.7% of NEU patients. The median CD34+ cell count on day +4 was significantly lower in BIO patients who needed PLEX than in those who did not (2.4 vs. 4.8 × 10³/ml; p = 0.002), as was the final CD34+ cell count (2.5 vs. 3.3 × 10⁶/kg; p 0.03). Mobilization failure rate was higher in the BIO group than in the NEU group (20 vs. 0%; p = 0.01). With respect to donors, more than one apheresis was needed in three BIO donors, one of them with PLEX. The use of BIO was the only risk factor for mobilization failure in patients who needed PLEX (hazard ratio 10.3; 95% confidence interval 1.3–77.8).

Conclusion

The study revealed that BIO had a lower efficacy for stem cell mobilization when the only treatment was G-CSF, especially in poor mobilizers needing PLEX.

Efficacy and Safety of Nivestim Versus Neupogen for Mobilization of Peripheral Blood Stem Cells for Autologous Stem Cell Transplantation

A retrospective cohort study was conducted in Singapore General Hospital to study the safety and efficacy of biosimilar granulocyte-colony stimulating factor (G-CSF) Nivestim for chemo-mobilization of stem cells for autologous stem cell transplant (autoSCT). All patients who underwent an autoSCT between January 2011 and December 2016 were screened for eligibility. A total of 194 patients were screened, and 131 were included. Nivestim was used in 65 patients and the originator G-CSF (Neupogen) in 66. Patient characteristics were similar between both arms except for chemo-mobilization regimen used (p < 0.0001). Mobilization success rates were found to be comparable, at 96.9% (Nivestim) and 97% (Neupogen). Adverse events rates were also similar. Median duration of G-CSF use and hospitalization were both found to be shorter in the Nivestim arm. Median drug acquisition cost per mobilization cycle was significantly lower in the Nivestim arm at $533.40 (range $213.40–$1280.20) as compared to $1261.90 (range $574–$2755.20) in the Neupogen arm (p < 0.0001). No difference was observed for neutrophil and platelet engraftment after autoSCT. Nivestim was found to be safe and non-inferior to Neupogen for chemo-mobilization of stem cells for autoSCT, and associated with lower cost and shorter length of hospitalization.

Biosimilars in oncology: A decade of experience with granulocyte colony-stimulating factor and its implications for monoclonal antibodies

Biosimilars offer the potential for improved sustainability of cancer care. In oncology, granulocyte colony-stimulating factor and erythropoiesis-stimulating agent biosimilars have been available for almost a decade, with biosimilars of monoclonal antibodies a more recent development. Sandoz biosimilar filgrastim was approved based on Phase III confirmatory studies conducted in patients with breast cancer experiencing chemotherapy-induced neutropenia, with other indications granted based on extrapolation. Despite the fact that extrapolation is a well-established scientific principle in regulation of biological medicines, it is a commonly misunderstood part of the biosimilar concept. Broad experience from almost a decade of use of Sandoz biosimilar filgrastim includes >21 million patient-days exposure and >9 years of real-world clinical evidence, indicates extrapolation successfully at work. Together, this can help reassure oncologists that extrapolation is based on sound scientific principles. Efforts to improve understanding of extrapolation are critical to ensure the acceptance of future oncology biosimilar monoclonal antibodies.

Trial Design and Statistical Considerations on the Assessment of Pharmacodynamic Similarity

Pharmacodynamics (PD) similarity is an important component to support the claim of similarity between two drugs or devices. This article investigates the trial design and statistical considerations in the equivalence test of PD endpoints. Using bone resorption marker CTX as a case study, the relationship between the PD readouts and drug potency was explored to evaluate the sensitivity of the PD endpoint and guide equivalence margin selection. For PD data that have high baseline variability, one conventional similarity assessment method was to apply baseline-normalization followed by the standard bioequivalence (BE) test (Lancet Haematol. 4:e350-61, 2017, Ann Rheum Dis. 2017). This study showcased the drawbacks of the conventional method for PD data that were close to inhibition saturation, as the baseline-normalization significantly skewed the distribution of the PD data toward non-log-normal. In such cases, the standard BE test can produce an inflated type I error. Alternatively, ANCOVA, when applied to the un-normalized PD data with the baseline as a covariate, produced a satisfactory type I error with sufficient power. Therefore, ANCOVA was recommended for equivalence test of PD markers that has a saturated inhibition profile and high variability at baseline. Moreover, the relationship between PD readouts and drug potency was used to explore the sensitivity of the PD endpoint and it could help justify the equivalence margins, since the standard 80% to 125% BE margin often does not apply to PD. Finally, a decision tree was proposed to help guide the design of the PD equivalence study in the choice of PD endpoints and statistical methods.

Proposed biosimilar pegfilgrastim shows similarity in pharmacokinetics and pharmacodynamics to reference pegfilgrastim in healthy subjects

AIMS

This study aimed to demonstrate that the pharmacokinetic (PK) and pharmacodynamic (PD) profile of Sandoz proposed biosimilar pegfilgrastim (LA-EP2006) matches reference pegfilgrastim (Neulasta® ) in healthy subjects. Safety and immunogenicity were also assessed.

METHODS

The phase I, randomized, double-blind, two-period crossover study consisted of two treatment periods separated by an 8-week washout period. Healthy subjects aged 18-45 were randomized to either proposed biosimilar/reference pegfilgrastim or reference pegfilgrastim/proposed biosimilar. Proposed biosimilar and reference pegfilgrastim were administered on Day 1 of each treatment period (single 6 mg subcutaneous injection). Blood samples for PK/PD analysis were taken predose and ≤336 h postdose. PK/PD similarity was claimed if 90% (PK) and 95% (PD) confidence intervals (CI) for geometric mean ratios of the area under the serum concentration-time curve (AUC) from time of dosing and extrapolated to infinity (AUC0-inf ), or to the last measurable concentration (AUC0-last ), maximum observed serum concentration (Cmax ), absolute neutrophil count (ANC) area under the effect curve from the time of dosing to the last measurable concentration (AUEC0-last ) and ANC maximum effect attributable to the therapy under investigation (Emax ) were completely contained within the predefined margin (0.8 to 1.25).

RESULTS

Overall, 169 subjects completed the study. PK/PD similarity was demonstrated; 90% CIs of geometric mean ratio of proposed biosimilar/reference for PK: AUC0-inf (1.0559-1.2244), AUC0-last (1.0607-1.2328), Cmax (1.0312-1.1909) and 95% CIs for PD (ANC): AUEC0-last (0.9948-1.0366), Emax (0.9737-1.0169) were completely contained within predefined margin of 0.8 to 1.25. Both biologics had similar safety profiles, were well tolerated and had low incidence of anti-drug antibodies. No neutralizing or clinically relevant antibodies were detected.

CONCLUSIONS

PK/PD similarity of Sandoz proposed biosimilar pegfilgrastim and reference pegfilgrastim was confirmed. No clinically meaningful differences in safety, tolerability and immunogenicity were observed in healthy subjects.

Comparison of biosimilar filgrastim with a reference product: pharmacokinetics, pharmacodynamics, and safety profiles in healthy volunteers

Purpose

Filgrastim, a granulocyte-colony stimulating factor, is used to treat patients with neutropenia, including neutropenic fever. Leucostim^® is a recombinant filgrastim product tested for biosimilarity with its reference product, Neupogen^®. We conducted a comparative clinical trial of the 2 products.

Patients and methods

A randomized, open-label, 2-way crossover, single-dose Phase I study was conducted for 56 healthy subjects. After a 5 and 10 μg/kg single subcutaneous administration of test and reference product, pharmacokinetic and pharmacodynamic parameters (absolute neutrophil count and CD34⁺ cell count) were compared. During the study, safety tests and adverse event monitoring were performed.

Results

The test and the reference products had a comparable pharmacokinetic, pharmacodynamic, and safety profile. In both 5 and 10 μg/kg dosing, the 90% CIs of the test to reference ratio for primary parameters (peak plasma concentration and area under the plasma concentration vs time curve from time 0 extrapolated to the infinite time for plasma filgrastim concentration; maximal effect and area under the time-effect curve from time 0 to time of the last quantifiable effect for absolute neutrophil count) were within the 0.8–1.25 range. In addition, safety profiles between the 2 products were similar without any serious adverse events.

Conclusion

This study has provided firm clinical evidence that the test filgrastim product is similar to its reference filgrastim product.

Compatibility of Biosimilar Filgrastim with Cytotoxic Chemotherapy during the Treatment of Malignant Diseases (VENICE): A Prospective, Multicenter, Non-Interventional, Longitudinal Study

Introduction

Febrile neutropenia (FN) is a serious and frequent complication of cytotoxic chemotherapy. Biosimilar filgrastim (Nivestim™, Hospira Inc, A Pfizer Company, Lake Forest, IL, USA) is a granulocyte-colony stimulating factor licensed for the treatment of neutropenia and FN induced by myelosuppressive chemotherapy. The primary goal of this VENICE study (ClinicalTrials.gov identifier, NCT01627990) was to observe the tolerability, safety and efficacy of biosimilar filgrastim in patients receiving cancer chemotherapy.

Methods

This was a prospective, multicenter, non-interventional, longitudinal study. Consenting adult patients with solid tumors or hematologic malignancies for whom cytotoxic chemotherapy and treatment with biosimilar filgrastim was planned were enrolled.

Results

Among the enrolled patients (N = 386), 81% were female, with a median age (range) of 61 (22–92) years, with 39% >65 years old. Most patients (n = 338; 88%) had solid tumors and the remainder (n = 49; 13%) had hematological malignancies. The majority of the patients (64%) received biosimilar filgrastim as primary prophylaxis and 36% as secondary prophylaxis. At the follow-up visits, for the majority of patients (95.6%) there had been no change in chemotherapy dose due to FN. For two patients (0.5%) the chemotherapy was discontinued due to FN and for four patients (1.0%) the chemotherapy dose was reduced due to FN. For the majority of patients (96.9%) the chemotherapy cycle following the first biosimilar filgrastim treatment was not delayed due to FN. For 3 patients (0.8%), the chemotherapy was delayed following the first biosimilar filgrastim treatment. Less than one-third (29.8%) of the patients experienced ≥1 adverse event that was at least potentially related to biosimilar filgrastim treatment.

Conclusions

Biosimilar filgrastim was effective and well-tolerated in both the primary and secondary prophylactic setting in patients undergoing chemotherapy for solid tumors and hematological malignancies.

Trial Registration

ClinicalTrials.gov identifier, NCT01627990.

Funding

Hospira Inc, A Pfizer Company, Lake Forest, IL, USA.

Algorithms utilizing peripheral blood hematopoietic progenitor cell counts in lieu of some CD34+ cell counts predict successful peripheral blood stem cell collections with substantial time and cost savings

Background and Objectives

Hematopoietic progenitor cell (HPC) counts from Sysmex hematology analyzers have been shown to correlate with peripheral blood (PB) CD34+ cell counts by flow cytometry. Algorithms utilizing HPC counts to guide stem cell collections have been proposed but rarely tested. This study describes the development and validation of algorithms utilizing HPC and PB CD34+cell counts to predict adequate peripheral blood stem cell (PBSC) collections for chemomobilized and cytokine-mobilized individuals.

Materials and Methods

Utilizing a test set of 83 PB samples from chemomobilized or cytokine-mobilized PBSC collection patients, PB CD34+ counts were correlated with HPC counts and a receiver operating characteristic curve was constructed. Cut-offs of ≤0.5 HPC/μl and ≥7 HPC/μl were established to maximize sensitivity and specificity for using HPC to predict PB CD34+ ≥ 10 cells/μl. These cut-offs were subsequently validated using a separate prospective validation set of 88 HPC/CD34+ cell sample pairs.

Results

Using the algorithms, all patients in the prospective validation data set achieved adequate collections of ≥1 × 10⁶ CD34⁺ cells/kg, and a 67% reduction in the number of CD34⁺ cell counts performed was achieved. This lead to a direct cost savings of at least $18,700 USD over a 21-month period (88% reduction in direct costs).

Conclusion

Use of the algorithms provides significant time and cost savings for the laboratory while accurately predicting (i) timing of PBSC collections to obtain adequate CD34⁺ product yields for chemomobilized patients and (ii) when to administer plerixafor to cytokine-mobilized patients to improve the likelihood of achieving adequate collections.

Mobilization of autologous and allogeneic peripheral blood stem cells for transplantation in haematological malignancies using biosimilar G-CSF

BACKGROUND AND OBJECTIVES

Biosimilars of the granulocyte colony stimulating factor (G-CSF) filgrastim were approved by the European Medicines Agency (EMA) for registered indications of the originator G-CSF, including prevention and treatment of neutropenia, as well as mobilization of peripheral blood stem cells in 2008. Nevertheless, there is still an ongoing debate regarding the quality, efficacy and safety of biosimilar G-CSF.

MATERIALS AND METHODS

This article is a meta-analysis of clinical studies on the use of biosimilar G-CSF for mobilization and transplantation of haematopoietic stem cells as available in public databases. All data sets were weighted for the number of patients and parameters and then subjected to statistical meta-analysis employing the Mann-Whitney U-test followed by the Hodges-Lehmann estimator to assess differences between biosimilar and originator G-SCF.

RESULTS

A total of 1892 individuals, mostly with haematological malignancies but also including 351 healthy donors have been successfully mobilized for autologous or allogeneic stem cell transplantation using biosimilar G-CSF (Zarzio(TM) : 1239 individuals; Ratiograstim(TM) /Tevagrastim(TM) : 653 individuals). A total of 740 patients with multiple myeloma, 491 with non-Hodgkin's lymphoma (NHL), 150 with Hodgkin's lymphoma (HL) and other diseases are included in this meta-analysis, as well as 161 siblings and 190 volunteer unrelated donors. For biosimilar and originator G-CSF, bioequivalence was observed for the yield of CD34+ stem cells as well as for the engraftment of the transplants.

CONCLUSION

Biosimilar G-CSF has equivalent effects and safety as originator G-CSF.

Histological study on the protective effect of endogenous stem-cell mobilization in Adriamycin-induced chronic nephropathy in rats

Chronic kidney disease is a global health problem with increasing morbidity and mortality. Therefore, this study was planned to test the protective effect of hematopoietic-stem-cell mobilization by granulocyte colony-stimulating factor (G-CSF) on Adriamycin (ADR)-induced chronic renal disease in rats. Thirty albino rats were equally divided into three groups: control, ADR group [rats received a single intravenous injection of ADR (5 mg/kg)], and G-CSF group [rats received ADR by the same route and the same dose as the previous group, and then G-CSF (70 μg/kg/d) 2 hours after ADR injection then daily for five consecutive days]. At the time of sacrifice (after 6 weeks), blood samples were taken to estimate the blood urea nitrogen and serum creatinine. Kidney sections were stained with hematoxylin and eosin, toluidine blue, Masson's trichrome, periodic acid–Schiff stains, and immunohistochemical staining against CD34 and caspase-3. The G-CSF group exhibited protection against renal injury manifested by reducing blood urea nitrogen and serum-creatinine levels, improving histological architecture, and increasing the proliferative capacity of renal tubules.

Comparison of the pharmacokinetic and pharmacodynamic properties of two recombinant granulocyte colony-stimulating factor formulations after single subcutaneous administration to healthy volunteers

BACKGROUND AND OBJECTIVE

The aim of this randomized, single dose, two-period crossover study with two weeks wash-out period was the demonstration of bioequivalence of two recombinant human granulocyte colony-stimulating factor (rG-CSF) formulations after subcutaneous administration of 300μg comparing their pharmacokinetic (primary endpoints AUC0-24, AUC0-∞ and Cmax) and pharmacodynamic (primary endpoints ANC AUC0-72, ANC AUC0-∞ and ANCmax) profiles in healthy male subjects.

MATERIALS AND METHODS

A total of 36 (23.0±6.0 years, 76.6±7.2kg) healthy subjects were recruited. Using a 1:1 randomization ratio, subjects were randomly assigned to one of two possible treatment-sequence groups to receive the single dose of test formulation (Gp-02) and reference product (Neupogen™) concentrations were measured by enzyme-linked immunosorbent assay (ELISA) up to 24h and the Absolute Neutrophil Count (ANC) was determined using hematology analyzer Coulter STKS™ (Beckman Coulter) up to 72h after injection. The geometric mean of primary pharmacokinetic and pharmacodynamic variables were considered bioequivalent if the 90% confidence intervals (CI) would fall in the bioequivalence range of 80%-125%.

RESULTS

AUC0-24 (ratio of means 103.4, 90% CI: 95.6-111.9), AUC0-∞ (103.4, 90% CI: 95.7-111.7), Cmax (99.6, 90% CI: 89.0-111.4), ANC AUC0-72 (100.0, 90% CI: 96.6-103.5), ANC AUC0-∞ (100.8, 90% CI: 96.5-105.3), and ANCmax (100.2, 90% CI: 95.4-105.1) were determined. Single doses of test and reference formulations were well tolerated. The incidence of AEs was equally distributed across treatment groups with the most frequent AEs being headache, fever, and back pain.

CONCLUSIONS

The study results demonstrated the bioequivalence of Gp-02, a new formulation of filgrastim, and the reference product Neupogen™.

Biosimilars: a cure to the U.S. health care cost conundrum?

As the cost of healthcare continues to rise and patents on biologics near expiration, biosimilars are gaining visibility as a mechanism for cost reduction. Yet, the introduction of biosimilars into the U.S. market will be complex, due to the related complexity of production, research requirements, and regulatory uncertainty. The purpose of this paper is to frame the relevant issues in order to provide context for stakeholders. It is particularly crucial that clinicians understand the scientific, regulatory, legislative and economic considerations involved in order to ensure that the path to approval is consistent with their needs and that appropriate utilization occurs, once approved.

Pharmacokinetics and pharmacodynamics of FSK0808 and Gran after single intravenous drip administration or single subcutaneous administration: comparative study in healthy Japanese adult male subjects

FSK0808 is a recombinant human granulocyte colony-stimulating factor developed by Fuji Pharma Co., Ltd and Mochida Pharmaceutical Co., Ltd. as a biosimilar product of Gran®. We verified the pharmacokinetic/pharmacodynamic equivalence of FSK0808 and commercially available Gran® by a randomized crossover study of single intravenous dose (200 µg/m(2)) and single subcutaneous dose (400 µg/m(2)) in healthy Japanese adult male subjects. According to the bioequivalence guidelines, the area under the blood concentration - time curve by 48 hours after administration (AUC0-48) in a single intravenous drip (IVD) study, and AUC0-48 and maximum blood concentration (Cmax) in a single subcutaneous (SC) dose study were used as primary endpoints, and the pharmacodynamic parameters including absolute neutrophil count (ANC) or number of CD34 positive cells (CD34(+) cells) as secondary endpoints. The safety was evaluated based on the characteristics and incidence of adverse reactions. As a result, the 90% confidence interval (CI) of the difference in mean value for AUC0-48 among drugs ranged from log(0.8) to log(1.25), in the IVD study, and those for Cmax and AUC0-48 were within the range of log(0.8)-log(1.25) in the SC study. Those for secondary endpoints were all within the range of log(0.8)-log(1.25). Thus, the pharmacokinetics/pharmacodynamics of both drugs were considered equivalent for all routes of administration, and the profiles of adverse reactions were also very similar.

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

Clinical experience with Zarzio® in Europe: what have we learned?

Biosimilars are similar, but non-identical, versions of existing biological drugs for which patents have expired. Despite the rigorous approval process for biosimilars, concerns have been expressed about the efficacy and safety of these products in clinical practice. Biosimilars of filgrastim, based on the originator product Neupogen®, have been available since 2008 and are now in widespread clinical use in Europe and elsewhere. Three biosimilar G-CSFs have been approved based on a combination of physicochemical and biological protein characterisation, pharmacokinetic and pharmacodynamic assessment in healthy volunteers and efficacy and safety data in patients with cancer. To assess whether biosimilars are effective in the real-world clinical practice setting, a pooled analysis of five post-approval studies of biosimilar G-CSF (Zarzio®) that included 1,302 adult patients who received at least one cycle of chemotherapy with G-CSF support for the prevention of neutropenia was conducted. A total of 36 % of patients had a febrile neutropenia risk of >20 %, while 39.6 % had a risk of 10-20 % based on chemotherapy regimen. The occurrence of severe or febrile neutropenia was within the range of that observed in previous studies of originator G-CSF. In addition, the safety profile of Zarzio® was consistent with that reported for originator G-CSF and the known safety profile of G-CSF. Initial concerns about the use of biosimilars, at least with regard to biosimilar G-CSFs, appear to be unfounded. Adoption of cost-effective biosimilars should help reduce healthcare costs and improve patient access to biological treatments.

Update on the safety and bioequivalence of biosimilars - focus on enoxaparin

Generic forms of chemically-derived drugs must exhibit chemical identity and be bioequivalent in healthy human subjects. The use of generic drugs results in a considerable savings of healthcare expenditures. Biologic drugs are produced in living systems or are derived from biologic material and extend beyond proteins to include antibodies, polysaccharides, polynucleotides, and live viral material. Such drugs pose a challenge to characterize as they tend to be larger in size than chemically-derived drugs, can exhibit a variety of post-translational modifications, and can have activities that are dependent on specific conformations. Biosimilars are not true generics, but rather, exhibit a high degree of similarity to the reference product and are considered to be biologically and clinically comparable to the innovator product. Therefore, the development process for biosimilars is more complex than for a true generic. Guidance is now available from the US Food and Drug Administration and from the European Medicines Agency for the development of biosimilar drugs. Biosimilar drugs are expected to have a major impact in the management of various diseases in coming years.

Clinical safety of biosimilar recombinant human granulocyte colony-stimulating factors

INTRODUCTION

A 'biosimilar', or 'similar biological medicinal product', is a biologic agent that is similar in terms of quality, safety and efficacy to an authorized reference biological medicine. Since the expiration of the filgrastim patent in Europe, three agents have received marketing authorization from the EMA: Tevagrastim, Zarzio and Nivestim. Tevagrastim has also been approved as a biologic by the FDA as tbo-filgrastim.

AREAS COVERED

Using the EMA dossiers (all three agents), the FDA dossier (Tevagrastim), and journal publications, this article reviews clinical safety data for these products with emphasis on serious/severe adverse events and special consideration of immunogenicity, bone pain, splenomegaly, allergic reactions, acute respiratory distress syndrome and mortality.

EXPERT OPINION

All three agents have similar safety profiles. None were statistically higher on safety parameters to what is known about originator filgrastim (Neupogen). What is known about filgrastim in general regarding safety can be extended to biosimilar filgrastim. Safety profiles may become more differentiated once long-term product-specific safety data are available. Large-sample, long-term, observational studies of real-world practice will provide the heterogeneity and statistical power to demonstrate product-specific safety profiles. Current evidence indicates that statistically no one product is less and no one product is more safe.

Characterization and comparison of commercially available TNF receptor 2-Fc fusion protein products

Because of rapidly increasing market demand and rising cost pressure, the innovator of etanercept (Enbrel®) will inevitably face competition from biosimilar versions of the product. In this study, to elucidate the differences between the reference etanercept and its biosimilars, we characterized and compared the quality attributes of two commercially available, biosimilar TNF receptor 2-Fc fusion protein products. Biosimilar 1 showed high similarity to Enbrel® in critical quality attributes including peptide mapping, intact mass, charge variant, purity, glycosylation and bioactivity. In contrast, the intact mass and MS/MS analysis of biosimilar 2 revealed a mass difference indicative of a two amino acid residue variance in the heavy chain (Fc) sequences. Comprehensive glycosylation profiling confirmed that biosimilar 2 has significantly low sialylated N-oligosaccharides. Biosimilar 2 also displayed significant differences in charge attributes compared with the reference product. Interestingly, biosimilar 2 exhibited similar affinity and bioactivity levels compared with the reference product despite the obvious difference in primary structure and partial physiochemical properties. For a biosimilar development program, comparative analytical data can influence decisions about the type and amount of animal and clinical data needed to demonstrate biosimilarity. Because of the limited clinical experience with biosimilars at the time of their approval, a thorough knowledge surrounding biosimilars and a case-by-case approach are needed to ensure the appropriate use of these products.

The safety of switching between therapeutic proteins

INTRODUCTION

The approval of several biosimilars in the past years has prompted discussion on potential safety risks associated with switching to and from these products. It has been suggested that switching may lead to safety concerns. However, data is limited on the clinical effects of switching.

AREAS COVERED

In this review we provide an overview of data related to switching between human recombinant growth hormones, erythropoietins and granulocyte colony stimulating agents. We reviewed data from clinical trials, pharmacovigilance databases and an overview of the literature on the frequency of switching between these products. The review covers both switching between innovator products within the same product class and switching to and from biosimilars.

EXPERT OPINION

Data on the frequency of switching in clinical practice is scarce, but it seems most frequent for erythropoietins. We have found no evidence from clinical trial data or post marketing surveillance data that switching to and from different biopharmaceuticals leads to safety concerns.

Intermittent granulocyte colony-stimulating factor maintains dose intensity after ABVD therapy complicated by neutropenia

INTRODUCTION

Granulocyte Colony-Stimulating Factor (G-CSF) is commonly used to maintain dose intensity in patients receiving ABVD chemotherapy (doxorubicin, bleomycin, vinblastine and dacarbazine) for Hodgkin lymphoma. However, the need for growth factor support is unclear, with studies suggesting that dose intensity can be maintained without G-CSF. Moreover, G-CSF is expensive (pegfilgrastim: EUR 1540/cycle; 300 μg filgrastim for 7 days: EUR 700/cycle) and is associated with side effects including bone pain and increased risk of bleomycin lung toxicity. Intermittent G-CSF may be an effective compromise, given that the effect of G-CSF on granulocyte precursors in vitro persists for 4-5 days after administration. After promising results of a pilot study, this schedule has been used subsequently in the majority of our patients receiving G-CSF as secondary prophylaxis for ABVD complicated by neutropenia.

METHODS

Retrospective analysis of the incidence of febrile neutropenia and treatment delay in a variety of different G-CSF schedules used as secondary prophylaxis in patients receiving ABVD.

RESULTS

848 cycles in 85 consecutive patients were evaluated. Most patients (86%) received G-CSF, generally commenced prophylactically for neutropenia when cycle 1B was due. Intermittent G-CSF (typically given on days 4, 8 and 12) was used in 413 cycles compared with daily or pegylated G-CSF in 99 cycles. In patients receiving intermittent G-CSF, the median neutrophil count, across all cycles, was 7.3 × 10(9) /L (range: 1.4-47.1) when the next scheduled chemotherapy was due. There were two cases of febrile neutropenia (0.45%) and no treatment delays. One patient developed possible bleomycin toxicity.

CONCLUSIONS

Intermittent G-CSF is effective in maintaining dose intensity in patients receiving ABVD.

Statistical Considerations in the Design of Biosimilar Cancer Clinical Trials

When the patent of an innovative (brand-name) small-molecule drug expires, generic copies of the innovative drug may be marketed if their therapeutic equivalence to the innovative drug has been shown. The small-molecule drugs are considered therapeutically equivalent and can be used interchangeably if two drugs are shown to be pharmaceutically equivalent with identical active substance and bioequivalent with comparable pharmacokinetics in a crossover clinical trial. However, the therapeutic equivalence paradigm cannot be applied to biosimilars since the active ingredients of biosimilars are huge molecules with complex and heterogeneous structures, and these molecules are difficult to replicate in every detail. The European Medicine Agency (EMEA) has introduced a regulatory biosimilar pathway which mandates clinical trials to show therapeutic equivalence. In this paper, we discuss statistical considerations in the design and analysis of biosimilar cancer clinical trials.