Pharmacokinetic and Pharmacodynamic Characteristics of Tripegfilgrastim, a Pegylated G-CSF, in Pediatric Patients with Solid Tumors.

A long-acting granulocyte colony-stimulating factor, tripegfilgrastim, was approved in Korea for the prevention of chemotherapy-induced neutropenia in adult patients. In this study, we evaluated the pharmacokinetics, pharmacodynamics, and safety of tripegfilgrastim in pediatric patients. A phase I, open-label, single ascending-dose study was performed in pediatric patients with solid tumors or lymphoma (ClinicalTrials.gov, NCT02963389). The patients were stratified according to age groups (aged 6 to 12 or 12 to 19 years) and received a single subcutaneous dose of tripegfilgrastim 60 µg/kg or 100 µg/kg. Tripegfilgrastim was administered 24 hours after the end of the chemotherapy, and serial blood sampling and safety monitoring were conducted. Twenty-seven patients with solid tumors were enrolled in this study. Tripegfilgrastim was detectable in plasma for an extended period (terminal half-life > 40 hours), and plasma concentrations increased slightly less than dose proportionally. The mean duration of grade 4 neutropenia was reduced as the average tripegfilgrastim concentration during the initial neutrophil recovery process increased. No substantial differences in the pharmacokinetic and pharmacodynamic responses were observed between the two age groups. When stratified by body weight, weighing more than 45 kg has a higher risk of a prolonged neutropenia period when receiving the lower dose (60 µg/kg) of tripegfilgrastim. Tripegfilgrastim was generally safe and well-tolerated in the pediatric patients. These results justify further clinical investigations of tripegfilgrastim at 100 µg/kg dose in pediatric patients.

A prospective study of filgrastim pharmacokinetics in morbidly obese patients compared with non-obese controls.

INTRODUCTION: Filgrastim is a human granulocyte colony-stimulating factor (G-CSF). There are limited data on dosing filgrastim in obesity. The objective of this study was to compare filgrastim pharmacokinetic parameters for morbidly obese and non-obese patients after a single subcutaneous dose of filgrastim dosed per actual body weight. METHODS: This prospective, matched-pair study (NCT01719432) included patients ≥18 years of age, receiving filgrastim at 5 µg/kg with a weight >190% of their ideal body weight (IBW) for "morbidly obese" patients or within 80%-124% of IBW for matched-control patients. The control group was prospectively matched for age (within 10 years), degree of neutropenia, and gender. Filgrastim doses were not rounded to vial size, to allow more accurate assessment of exposure. Blood samples were collected at 0 (prior to dose), 2, 4, 6, 8, 12, and 24 h after the first subcutaneous administration of filgrastim. RESULTS: A total of 30 patients were enrolled in this prospective pharmacokinetic study, with 15 patients assigned to each arm. Non-compartmental analysis showed that the systemic clearance (Cl) was 0.111 ± 0.041 ml/min in the morbidly obese group versus 0.124 ± 0.045 ml/min in the non-obese group (p = 0.44). Additionally, the mean area under the curve (AUC0-24h ) was 49.3 ± 13.9 ng/ml × min in the morbidly obese group versus 46.3 ± 16.8 ng/mL x min in the non-obese group (p = 0.6). No differences were seen in maximum concentrations (Cmax ) between the two groups (morbidly obese: 48.1 ± 14.7 ng/ml vs. non-obese: 49.2 ± 20.7 ng/ml (p = 0.87)). The morbidly obese group had a numerically higher, but not statistically significant, increase in time to maximum concentration (Tmax ) compared to the non-obese group (544 ± 145 min vs 436 ± 156 min (p = 0.06), respectively). CONCLUSION: Calculating subcutaneous filgrastim doses using actual body weight appears to produce similar systemic exposure in morbidly obese and non-obese patients with severe neutropenia.

Pharmacokinetics and Pharmacodynamics of a Proposed Pegfilgrastim Biosimilar MSB11455 Versus the Reference Pegfilgrastim Neulasta in Healthy Subjects: A Randomized, Double-blind Trial.

PURPOSE: MSB11455 is a proposed biosimilar to the reference pegfilgrastim (Neulasta®). This pivotal equivalence study (NCT03251248) assessed the pharmacokinetic and pharmacodynamic equivalence of MSB11455 to the reference product. METHODS: This 2-way, 2-sequence, group-sequential, crossover study was conducted in healthy subjects. Subjects received a single subcutaneous dose of MSB11455 or the reference product (both 6 mg/0.6 mL) on Day 1 of each study period. Pharmacokinetic and pharmacodynamic (absolute neutrophil count; ANC) samples were taken predose and up to day 16 post-dose. Non-compartmental parameters were calculated. Immunogenicity samples were taken pre-dose and up to day 84 after the first dose. Safety was assessed throughout the study. FINDINGS: A total of 292 subjects were randomized to therapy and treated; 244 received both treatments. For all primary pharmacokinetic and pharmacodynamic parameters, 90% repeated confidence intervals of geometric means ratio of MSB11455 to the reference product were within the pre-defined equivalence range (80.00%-125.00%) for AUC0-∞ (96.59-112.82); AUC0-last (97.29-113.96), Cmax (97.13-114.99), maximum observed effect on ANC (98.74-102.39), and area under the effect-time curve from time zero to time to last quantifiable concentration (97.30-100.23). Safety, tolerability, and immunogenicity were comparable between treatments. No filgrastim-specific neutralizing antibodies were detected with either treatment sequence. IMPLICATIONS: Pharmacokinetic and pharmacodynamic equivalence of MSB11455 and the reference product was shown, with comparable immunogenicity, safety, and tolerability between treatments. The study supports the biosimilarity of MSB11455 to the reference product. ClinicalTrials.gov identifier: NCT03251248.

The ELISA Detectability and Potency of Pegfilgrastim Decrease in Physiological Conditions: Key Roles for Aggregation and Individual Variability.

PEGylated recombinant human granulocyte colony stimulating factor (pegfilgrastim) is used clinically to accelerate immune reconstitution following chemotherapy and is being pursued for biosimilar development. One challenge to overcome in pegfilgrastim biosimilar development is establishing pharmacokinetic (PK) similarity, which is partly due to the degree of PK variability. We herein report that commercially available G-CSF and PEG ELISA detection kits have different capacities to detect pegfilgrastim aggregates that rapidly form in vitro in physiological conditions. These aggregates can be observed using SDS-PAGE, size-exclusion chromatography, dynamic light scattering, and real-time NMR analysis and are associated with decreased bioactivity as reflected by reduced drug-induced cellular proliferation and STAT3 phosphorylation. Furthermore, individual variability in the stability and detectability of pegfilgrastim in human sera is also observed. Pegfilgrastim levels display marked subject variability in sera from healthy donors incubated at 37 °C. The stability patterns of pegfilgrastim closely match the stability patterns of filgrastim, consistent with a key role for pegfilgrastim's G-CSF moiety in driving formation of inactive aggregates. Taken together, our results indicate that individual variability and ELISA specificity for inactive aggregates are key factors to consider when designing and interpreting studies involving the measurement of serum pegfilgrastim concentrations.

Differential role of r-met-hu G-CSF on male reproductive function and development in prepubertal domestic mammals.

The understanding of mammalian spermatogenesis niche factors active during sexual development may be leveraged to impact reproduction in farm animals. The aim of this study was to evaluate the effects of r-met-hu/G-CSF (filgrastim) on prepubertal sexual development of guinea pigs (Cavia porcellus) and ram lambs (Ovis aries). Individuals of both species were administered r-met-hu/G-CSF daily for 4 days. During and after administration protocols, testicular function and development were assessed through hematological responses, hormonal profiles (gonadotropins, testosterone and cortisol) testicular morphometry and germ cell kinetics. As expected, r-met-hu/G-CSF acutely mobilized white-lineage blood cells in both species. LH was increased by r-met-hu/G-CSF in guinea pigs (P<0.01) but T remained unchanged. In ram lambs gonadotropins and T increased in dose-response fashion (P<0.01) while cortisol values were stable and similar in treated and control animals (P>0.05). In guinea pigs there were no differences in testicular weights and volumes 2-mo after r-met-hu/G-CSF application (P>0.05). However, ram lambs showed a dose-response effect regarding testis weight (P<0.05). 66.66% of ram lambs had initial testes not yet in meiosis or starting the first spermatogenic wave. After 60-days only 25% of control animals were pubertal while all treated animals (1140-µg) had reached puberty. We propose an integrated hypothesis that G-CSF can stimulate spermatogenesis through two possible ways. 1) r-met-hu/G-CSF may go through the brain blood barrier and once there it can stimulate GnRH-neurons to release GnRH with the subsequent release of gonadotrophins. 2) a local testicular effect through stimulation of steroidogenesis that enhances spermiogenesis via testosterone production and a direct stimulation over spermatogonial stem cells self-renewal. In conclusion, this study shows that r-met-hu/G-CSF differentially affects prepubertal sexual development in hystricomorpha and ovine species, a relevant fact to consider when designing methods to hasten sexual developmental in mammalian species.

Pharmacokinetics, pharmacodynamics, safety, and immunogenicity of Pelmeg®, a pegfilgrastim biosimilar in healthy subjects.

A pharmacokinetics (PK)/pharmacodynamics (PD) study (EudraCT number 2015-002966-21) was conducted to investigate the biosimilarity of Pelmeg® (pegfilgrastim), a biosimilar to EU-authorized Neulasta®, which is used in the clinic for prevention of chemotherapy-induced neutropenia. The single-dose, randomized, double-blind, two-way crossover study comprised 171 healthy male subjects, receiving Pelmeg and Neulasta (6 mg as subcutaneous injection) in a sequential manner. Primary PK endpoints were the area under the concentration curve from time zero to last measurable concentration (AUC0-last) and the maximum concentration (Cmax). The primary PD endpoint was the area under the effect curve (AUEC0-last) for absolute neutrophil count (ANC). Safety and immunogenicity were also assessed. Comparability was demonstrated for both PK endpoints, with geometric mean ratios (test/reference) for AUC0-last and Cmax of 95.2% and 92.8%, respectively. The corresponding confidence intervals (CIs; 94.3%) were [86.6%;104.7%] for AUC0-last and [84.4%;102.2%] for Cmax, both being within the equivalence margin of 80.0% to 125.0%. Likewise, PD comparability was demonstrated, with the geometric mean ratio (test/reference) of AUEC0-last of 100.2%, with a corresponding CI (95%) of 98.7%-101.8%. No clinically meaningful differences were observed for safety and immunogenicity between Pelmeg and Neulasta. Pelmeg was found to be highly similar to the reference product.

Pharmacodynamics, safety, and immunogenicity of Pelmeg®, a pegfilgrastim biosimilar in healthy subjects.

A pharmacodynamics (PD) and immunogenicity study was conducted to investigate biosimilarity of Pelmeg®, a pegfilgrastim biosimilar to EU-authorized Neulasta®. The multiple-dose, randomized, double-blind, two-sequence, and three-period cross-over study comprised 96 healthy male subjects, receiving Pelmeg (Test [T]) and Neulasta (Reference [R]) in a sequential manner (T-T-R vs R-R-T). Subjects were dosed with 3 mg pegfilgrastim, as this dose was previously shown to be in the ascending part of the dose-response curve for PD. The primary PD endpoint was the area under the effect curve (AUEC0-last) for absolute neutrophil count (ANC). The primary immunogenicity endpoint was proportion of anti-drug antibody (ADA)-positive subjects at the end of Period 2 (ie, after administration of two doses of the same study drug). Comparability was demonstrated for the PD endpoint, with the geometric mean ratio (T/R) of AUEC0-last being 101.59%, with a corresponding 95% CI of [99.58; 103.63]. Of note, when using tighter acceptance limits (90.00%-111.00%), comparability between test and reference was shown as well. Only two confirmed ADA positive samples were detected, one after treatment with Pelmeg and one after Neulasta. These had a low ADA titer, no filgrastim reactivity, and no neutralizing capacity. No clinically meaningful differences in safety between Pelmeg and Neulasta were observed. Overall, the results from this study confirmed the biosimilarity of Pelmeg and Neulasta for PD and immunogenicity, as shown already at the bioanalytical level and in the pivotal PK/PD study with Pelmeg.

LA-EP2006: A Pegfilgrastim Biosimilar.

LA-EP2006 (Ziextenzo®) is the fifth biosimilar of pegfilgrastim, a pegylated recombinant granulocyte colony-stimulating factor, to be approved in the EU. It is approved for use in adults treated with cytotoxic chemotherapy for malignancy (with the exception of chronic myeloid leukaemia and myelodysplastic syndromes) to reduce the duration of neutropenia and the incidence of febrile neutropenia. LA-EP2006 matched reference pegfilgrastim in terms of physicochemical characteristics and functional properties, and the pharmacodynamic and pharmacokinetic similarity of the medicines has been shown in healthy volunteers. LA-EP2006 demonstrated clinical efficacy equivalent to that of EU-sourced reference pegfilgrastim in adult women with breast cancer receiving chemotherapy. The tolerability and safety profile of and the incidence of anti-drug antibodies with LA-EP2006 were similar to those of EU-sourced reference pegfilgrastim in this patient population. The role of reference pegfilgrastim in the management of chemotherapy-induced neutropenia is well established and LA-EP2006 provides an effective biosimilar alternative for patients requiring pegfilgrastim therapy.

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.

Pharmacokinetic and pharmacodynamic bioequivalence study of a pegfilgrastim biosimilar INTP5 in healthy subjects.

PURPOSE: This study compared pharmacokinetics, pharmacodynamics, safety and immunogenicity profiles of INTP5 (a potential pegfilgrastim biosimilar) with that of Neulasta®. METHODS: In this randomised, assessor-blind, crossover study, 344 healthy subjects received single subcutaneous dose of both INTP5 and Neulasta at 3 mg/0.3 ml (n = 172) or 6 mg/0.6 ml (n = 172) dose. The primary endpoints were AUC0-t, AUC0-∞ and Cmax of pegfilgrastim; and AUEC0-t and Emax of absolute neutrophil count (ANC). RESULTS: All 344 subjects dosed were included in the safety and immunogenicity analyses, and 292 subjects in the pharmacokinetic and pharmacodynamic analyses. At 6 mg dose, test to reference ratio (90% CI) of AUC0-t was 105.65% (99.60-112.06%), AUC0-∞ was 105.72% (99.55-112.28%) and Cmax was 103.62% (98.19-109.35%); while test to reference ratio (95% CIs) of ANC AUEC0-t was 100.79% (97.75-103.92%) and Emax was 98.70% (95.52-101.98%). Both the primary endpoints met the bioequivalence criteria (CIs within 80-125%). Similarly, at 3 mg dose, these endpoints were within the acceptance range of 80-125%. CD34+ profiles were similar and 95% CIs were within acceptance range at both doses. Adverse events were reported in 54 (15.7%; 8.72% in INTP5 vs. 8.39% in Neulasta) subjects; most events were mild. The incidences of anti-drug antibodies were low and similar between INTP5 and Neulasta and no neutralising antibodies were detected. CONCLUSIONS: Pharmacokinetic and pharmacodynamic bioequivalence was established between INTP5 and Neulasta following 3 and 6 mg doses. Safety and immunogenicity profiles were similar between INTP5 and Neulasta.

A pharmacokinetics and pharmacodynamics equivalence trial of the proposed pegfilgrastim biosimilar, MYL-1401H, versus reference pegfilgrastim.

PURPOSE: Pegfilgrastim is a long-acting granulocyte colony-stimulating factor indicated for prevention of febrile neutropenia in patients receiving myelosuppressive chemotherapy by promoting neutrophil recovery. METHODS: This phase 1, randomized, double-blind, three-way crossover trial in healthy volunteers evaluated the pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability of the proposed biosimilar, comparing MYL-1401H, reference pegfilgrastim (Neulasta®, Amgen Inc, Thousand Oaks, CA, USA) sourced from the European Union, and reference pegfilgrastim sourced from the USA. Primary PK end points were peak plasma concentration of pegfilgrastim (Cmax) and area under the plasma concentration-time curve from the time of dosing to infinity (AUC0-inf). Primary PD end points were area under the curve above baseline for absolute neutrophil counts (ANC AUC0-t) and maximum change from baseline for ANC (ANC Cmax). Adverse events were also recorded. RESULTS: The primary PK and PD end points were similar across all groups. For the PK parameters, the 90% confidence intervals (CIs) of the ratios of geometric means ranged between 0.91 and 1.18, which were within the predefined bioequivalence interval of 0.8000 to 1.2500 for all comparisons. For the PD parameters, the 95% CIs of the ratios of geometric means ranged between 0.94 and 1.06 for all comparisons, which were within the predefined PD equivalence interval of 0.8500 to 1.1765. The safety profiles were similar, with the most common adverse events being back pain and headache. CONCLUSIONS: MYL-1401H demonstrated similar PK, PD, and safety to reference pegfilgrastim in healthy volunteers and may be an equivalent option for the prevention of febrile neutropenia.

Pharmacokinetic-pharmacodynamic modelling of neutrophil response to G-CSF in healthy subjects and patients with chemotherapy-induced neutropenia.

AIM: The objective of the present study was to use pharmacokinetic-pharmacodynamic modelling to characterize the effects of chemotherapy on the granulopoietic system and to predict the absolute neutrophil counts (ANCs) for patients with chemotherapy-induced neutropenia treated with filgrastim and pegfilgrastim. METHODS: Data were extracted from 10 phase I-III studies conducted in 110 healthy adults, and 618 adult and 52 paediatric patients on chemotherapy following administration of filgrastim or pegfilgrastim. The structural model accounted for ANC dynamics and the effects of filgrastim and pegfilgrastim, chemotherapy and corticosteroids. The impact of neutrophils on drug disposition was based on a drug receptor-binding model that assumed quasi-equilibrium and stimulation of the production and maturation of neutrophils upon treatment. The chemotherapy and corticosteroid effects were represented by kinetic-pharmacodynamic-type models, where chemotherapy stimulated elimination of neutrophil precursors at the mitotic stage, and corticosteroids stimulated neutrophil production. RESULTS: The systemic half-lives of filgrastim (2.6 h) and pegfilgrastim (10.1 h) were as expected. The effective half-life of chemotherapy was 9.6 h, with a 2-day killing effect. The rate of receptor elimination from mitotic compartments exhibited extreme interindividual variability (% coefficient of variation >200), suggesting marked differences in sensitivity to chemotherapy effects on ANCs. The stimulatory effects of pegfilgrastim were significantly greater than those of filgrastim. Model qualification confirmed the predictive capability of this model. CONCLUSION: This qualified model simulates the time course of ANC in the absence or presence of chemotherapy and predicts nadir, time to nadir and time of recovery from different grades of neutropenia upon treatment with filgrastim and pegfilgrastim.

Model-based optimization of G-CSF treatment during cytotoxic chemotherapy.

PURPOSE: Although G-CSF is widely used to prevent or ameliorate leukopenia during cytotoxic chemotherapies, its optimal use is still under debate and depends on many therapy parameters such as dosing and timing of cytotoxic drugs and G-CSF, G-CSF pharmaceuticals used and individual risk factors of patients. METHODS: We integrate available biological knowledge and clinical data regarding cell kinetics of bone marrow granulopoiesis, the cytotoxic effects of chemotherapy and pharmacokinetics and pharmacodynamics of G-CSF applications (filgrastim or pegfilgrastim) into a comprehensive model. The model explains leukocyte time courses of more than 70 therapy scenarios comprising 10 different cytotoxic drugs. It is applied to develop optimized G-CSF schedules for a variety of clinical scenarios. RESULTS: Clinical trial results showed validity of model predictions regarding alternative G-CSF schedules. We propose modifications of G-CSF treatment for the chemotherapies 'BEACOPP escalated' (Hodgkin's disease), 'ETC' (breast cancer), and risk-adapted schedules for 'CHOP-14' (aggressive non-Hodgkin's lymphoma in elderly patients). CONCLUSIONS: We conclude that we established a model of human granulopoiesis under chemotherapy which allows predictions of yet untested G-CSF schedules, comparisons between them, and optimization of filgrastim and pegfilgrastim treatment. As a general rule of thumb, G-CSF treatment should not be started too early and patients could profit from filgrastim treatment continued until the end of the chemotherapy cycle.

Characterisation of the site-specific monoPEGylated rhG-CSF analogue pegteograstim.

We describe the characterisation of a novel monoPEGylated recombinant human granulocyte colony-stimulating factor analogue, pegteograstim (Neulapeg), prepared by site-specific 20 kDa maleimide-PEG conjugation. An additional cysteine was inserted between Gly136 and Ala137 of filgrastim (methionyl human granulocyte colony-stimulating factor) for site-specific PEGylation, and Cys18 of filgrastim was replaced with Ser18 to prevent unwanted PEGylation. Pegteograstim was produced by Escherichia coli and purified by cation exchange chromatography, and its structural, physicochemical, biological and immunological properties were investigated. Male Sprague-Dawley rats were administered pegteograstim (100 µg/kg) and the pharmacokinetics and pharmacodynamics compared with those of filgrastim. The results of long-term stability testing of pegteograstim revealed no significant change in its quality attributes at 2-8 °C for 36 months. In addition, pegteograstim was stable under the accelerated conditions (25 ± 2 °C, RH of 60 ± 5%) for 6 months. The site-specific monoPEGylated pegteograstim is a highly pure, stable and novel drug for long-lasting treatment of chemotherapy-induced neutropenia.

A phase III, randomized, non-inferiority study comparing the efficacy and safety of biosimilar filgrastim versus originator filgrastim for chemotherapy-induced neutropenia in breast cancer patients.

OBJECTIVES:: To compare the efficacy and safety of two filgrastim formulations for controlling chemotherapy-induced neutropenia and to evaluate the non-inferiority of the test drug relative to the originator. METHODS:: This phase III non-inferiority study had a randomized, multicenter, and open-label design. The patients were randomized at a ratio of 1:1 with a follow-up period of 6 weeks for each patient. In both study arms, filgrastim was administered subcutaneously at a daily dose of 5 mg/kg body weight. The primary endpoint was the rate of grade 4 neutropenia in the first treatment cycle. The secondary endpoints were the duration of grade 4 neutropenia, the generation of anti-filgrastim antibodies, and the rates of adverse events, laboratory abnormalities, febrile neutropenia, and neutropenia of any grade. RESULTS:: The primary efficacy analysis demonstrated the non-inferiority of the test drug compared with the originator drug; the upper limit of the 90% confidence interval (CI) for the rate of neutropenia between the two groups (12.61%) was lower than the established margin of non-inferiority. The two treatments were similar with respect to the secondary endpoints and safety. CONCLUSION:: The efficacy and safety profile of the test drug were similar to those of the originator product based on the rate of grade 4 neutropenia in the first treatment cycle. This study supports Anvisa's approval of the first biosimilar drug manufactured by the Brazilian industry (Fiprima¯).

A phase III, randomized, non-inferiority study comparing the efficacy and safety of biosimilar filgrastim versus originator filgrastim for chemotherapy-induced neutropenia in breast cancer patients

OBJECTIVES: To compare the efficacy and safety of two filgrastim formulations for controlling chemotherapy-induced neutropenia and to evaluate the non-inferiority of the test drug relative to the originator. METHODS: This phase III non-inferiority study had a randomized, multicenter, and open-label design. The patients were randomized at a ratio of 1:1 with a follow-up period of 6 weeks for each patient. In both study arms, filgrastim was administered subcutaneously at a daily dose of 5 mg/kg body weight. The primary endpoint was the rate of grade 4 neutropenia in the first treatment cycle. The secondary endpoints were the duration of grade 4 neutropenia, the generation of anti-filgrastim antibodies, and the rates of adverse events, laboratory abnormalities, febrile neutropenia, and neutropenia of any grade. RESULTS: The primary efficacy analysis demonstrated the non-inferiority of the test drug compared with the originator drug; the upper limit of the 90% confidence interval (CI) for the rate of neutropenia between the two groups (12.61%) was lower than the established margin of non-inferiority. The two treatments were similar with respect to the secondary endpoints and safety. CONCLUSION: The efficacy and safety profile of the test drug were similar to those of the originator product based on the rate of grade 4 neutropenia in the first treatment cycle. This study supports Anvisa’s approval of the first biosimilar drug manufactured by the Brazilian industry (Fiprima¯).

A cell-level model of pharmacodynamics-mediated drug disposition.

We aimed to develop a cell-level pharmacodynamics-mediated drug disposition (PDMDD) model to analyze in vivo systems where the PD response to a drug has an appreciable effect on the pharmacokinetics (PK). An existing cellular level model of PD stimulation was combined with the standard target-mediated drug disposition (TMDD) model and the resulting model structure was parametrically identifiable from typical in vivo PK and PD data. The PD model of the cell population was controlled by the production rate k in and elimination rate k out which could be stimulated or inhibited by the number of bound receptors on a single cell. Simulations were performed to assess the impact of single and repeated dosing on the total drug clearance. The clinical utility of the cell-level PDMDD model was demonstrated by fitting published data on the stimulatory effects of filgrastim on absolute neutrophil counts in healthy subjects. We postulated repeated dosing as a means of detecting and quantifying PDMDD as a single dose might not be sufficient to elicit the cellular response capable of altering the receptor pool to visibly affect drug disposition. In the absence of any PD effect, the model reduces down to the standard TMDD model. The applications of this model can be readily extended to include chemotherapy-induced cytopenias affecting clearance of endogenous hematopoietic growth factors, different monoclonal antibodies and immunogenicity effects on PK.

Confirmation of Biosimilarity in a Pharmacokinetic/Pharmacodynamic Study in Healthy Volunteers for an Analytically Highly Similar Pegfilgrastim.

A phase 1 pharmacokinetic (PK) and pharmacodynamic (PD) study was conducted to demonstrate similarity of a proposed pegfilgrastim biosimilar to its reference product. In a single-dose, randomized, assessor-blinded, 2-way crossover, active-controlled PK/PD study, 66 healthy adults received the proposed pegfilgrastim biosimilar and US-licensed pegfilgrastim reference product. Primary end points were pegfilgrastim AUCt and Cmax (PK), and absolute neutrophil count AUECt and Emax (PD). Safety and immunogenicity were also measured. Fifty-six subjects completed both arms of the study. Mean pegfilgrastim concentration-time profile for both products was similar, with the 90% confidence intervals (CI) of the relative mean ratio for the primary end points falling within the predefined acceptance criteria of 80%-125% (91.7%-116.1% and 86.7%-110.2% for AUCt and Cmax , respectively). PD similarity was also demonstrated by the 95%CI of the relative mean ratio of the primary end point parameters within the predefined acceptance margins of 80%-125% (96.0%-101.6% and 92.6%-100.1% for AUECt and Emax , respectively). No statistically meaningful PK/PD differences were observed. No clinically meaningful safety or immunological differences were observed with the proposed pegfilgrastim biosimilar that were not previously identified with the reference product. The proposed pegfilgrastim biosimilar product is highly similar to the reference product with regard to PK/PD.

Biosimilar Filgrastim in Autologous Peripheral Blood Hematopoietic Stem Cell Mobilization and Post-Transplant Hematologic Recovery.

To date, two kinds of Granulocyte Colony-Stimulating Factors (G-CSF) have been approved for autologous peripheral blood hematopoietic stem cell (PBSCs) mobilization and posttransplant hematologic recovery after high-dose chemotherapy: filgrastim (originator and biosimilar) and lenograstim. Biosimilar filgrastim has been approved on the basis of comparable efficacy and safety in clinical studies where it has been used as chemotherapy-induced febrile neutropenia prophylaxis, but no specific pre-registration studies have been published in the transplant setting. Hence, there is still general skepticism about the role of biosimilar G-CSFs in this setting of patients. This review of biochemical, pre-clinical and clinical data suggests significant comparability of biosimilar filgrastim with both originator filgrastim and lenograstim in autologous PBSCs mobilization and post-autograft hematologic recovery.