Use of Filgrastim for Ticlopidine Induced Neutropenia Following Coronary Stenting.
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Journal Article↗
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Filgrastim.
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Acquired Immunodeficiency Syndrome↗
[Filgrastim--a hematopoietic growth factor (r-metHuC-CSF) for treatment of neutropenia caused by cytostatics].
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Antineoplastic Agents↗
Criteria for use of filgrastim (granulocyte colony-stimulating factor).
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Antineoplastic Agents↗
Cost-effectiveness of autologous bone marrow transplantation.
The impact of filgrastim on the use of health care resources during recovery from autologous bone marrow transplantation (ABMT) was studied. The charts for patients with metastatic breast cancer treated with ABMT at a general hospital between November 1989 and July 1993 were reviewed by Blue Cross of Western Pennsylvania. The 58 patients were divided into five groups: group 1-bone marrow purged, no filgrastim therapy; group 2-bone marrow not purged, no filgrastim therapy; group 3-bone marrow purged, filgrastim therapy after ABMT; group 4-bone marrow not purged, filgrastim therapy after ABMT; and group 5-peripheral blood stem cells (PBSCs) given, followed by filgrastim therapy. The groups were compared for total length of stay (LOS), number of days the absolute neutrophil count (ANC) was < 500/cu mm, total number of days of filgrastim therapy, and total number of cumulative unit days of antimicrobial use. Total LOS was shorter for patients who received filgrastim (groups 3-5) than for patients who did not. Filgrastim was associated with fewer days of ANC < 500/cu mm in groups 4 and 5. The total number of cumulative unit days of antimicrobial use was lower in filgrastim recipients. Patients who received PBSCs needed fewer days of filgrastim therapy than the other filgrastim recipients. The health insurance company determined that, as a result of filgrastim therapy and PBSC transplantation, ABMT costs to the company have dropped by more than 50% since 1990. Patients now have available an alternative to conventional therapy for metastatic breast cancer without prejudice or penalty from their payer.
Bone Marrow Purging↗
Randomized study of recombinant human granulocyte colony-stimulating factor after high-dose chemotherapy and autologous bone marrow transplantation for high-risk lymphoid malignancies.
PURPOSE: The aim of this prospective randomized trial was to examine the efficacy and safety of filgrastim after high-dose chemotherapy and autologous bone marrow transplantation (ABMT). PATIENTS AND METHODS: Patients with poor-risk non-Hodgkin's lymphoma or relapsed Hodgkin's disease were treated in a randomized, open-label trial to study the use of filgrastim as an adjunct to high-dose chemotherapy and ABMT. Of 43 assessable patients, 19 were randomized to receive filgrastim by continuous subcutaneous infusion at a dose of 10 micrograms/kg/d, 10 to filgrastim 20 micrograms/kg/d, and 14 to a parallel control group that received no filgrastim after ABMT. RESULTS: For all filgrastim-treated patients analyzed together, the median time to neutrophil recovery > or = 0.5 x 10(9)/L after the day of ABMT was significantly accelerated to 10 days compared with 18 days in control patients (P = .0001). The median number of platelet transfusions was identical in both groups. Clinical parameters, including the median number of days with fever (1 v 4, P = .0418) and neutropenic fever (5 v 13.5, P = .0001) were significantly shorter in the filgrastim than in the control group. The number of days on intravenous antibiotics and duration of hospitalization were also shorter in the treated groups; however, the differences did not reach statistical significance. For patients treated with the two different dose levels of filgrastim, the neutrophil recovery and clinical results were similar. Filgrastim-associated toxicity appeared to be minimal, with five adverse events considered at least possibly related to filgrastim: two in the higher-dose group and three in the lower-dose group. All of these were rated moderate, except one case of severe bone pain that did not preclude continued filgrastim treatment at a lower dose. Survival and relapse-free survival were similar for control and filgrastim-treated patients. CONCLUSION: Taken together, the results of this first randomized study support the role of filgrastim given as an adjunct to ABMT in accelerating neutrophil recovery, as well as in reducing treatment-related morbidity and overall duration of the treatment procedure.
Adolescent↗
A randomized study of granulocyte colony-stimulating factor applied during and after chemotherapy in patients with poor risk myelodysplastic syndromes: a report from the HOVON Cooperative Group. Dutch-Belgian Hemato-Oncology Cooperative Group.
The purpose of this study was to determine the safety and efficacy of filgrastim as an adjunct to induction and consolidation chemotherapy in poor risk patients with myelodysplastic syndrome (MDS). Filgrastim was given both during and after chemotherapy with the objective to accelerate hematopoietic repopulation and enhance the efficacy of chemotherapy. In a prospective randomized multicentre phase II trial, a total of 64 patients with poor risk primary MDS were randomized to receive either granulocyte colony-stimulating factor (G-CSF, filgrastim, AMGEN, Breda, The Netherlands) 5 microg/kg/day subcutaneously or no G-CSF in addition to daunomycin (30 mg/m2/days 1, 2 and 3 intravenous bolus) and cytarabine (200 mg/m2 days 1-7, continuous infusion). The overall complete response rate was 63%: 73% for patients receiving filgrastim as compared to 52% in the standard arm (P = 0.08). Overall survival at 2 years was estimated at 29% for patients assigned to the filgrastim arm and 16% for control patients (P = 0.22). The median time for recovery of granulocytes towards 1.0 x 10(9)/l post-chemotherapy was 23 days in the filgrastim-treated patients vs 35 days in the standard arm (P = 0.015). There were no differences in time of platelet recovery, length of hospital stay, duration of antibiotic use or infectious complications between the two treatment groups. However the earlier recovery of neutrophils in the filgrastim group was associated with a reduced interval of 9 days between the induction and consolidation cycle. In patients with poor risk MDS the use of filgrastim during and after induction therapy results in a significantly reduced neutrophil recovery time. Further study may be warranted to see if the apparent trend of the improved response to chemotherapy in combination with filgrastim can be confirmed in greater number of patients and to assess the effect of the addition of filgrastim on survival.
Adult↗
Comparison of two different schedules of granulocyte-colony-stimulating factor during treatment for acute lymphocytic leukemia with a hyper-CVAD (cyclophosphamide, doxorubicin, vincristine, and dexamethasone) regimen.
BACKGROUND: Although the safety and efficacy of granulocyte-colony-stimulating factor (G-CSF) (filgrastim) in the treatment of hematologic malignancies has been well established, to the authors' knowledge the optimal timing of filgrastim administration during remission induction chemotherapy and consolidation chemotherapy has not been determined. The purpose of the current study was to determine whether a delay in the administration of filgrastim from Day 5 to Day 10 during chemotherapy with a hyper-CVAD (cyclophosphamide, doxorubicin, vincristine, and dexamethasone) regimen resulted in a longer time to neutrophil or platelet count recovery or increased the incidence of infection. METHODS: One hundred ninety-nine patients who achieved complete disease remission after a single course of induction chemotherapy were considered for evaluation. Induction chemotherapy was with hyper-CVAD (fractionated cyclophosphamide, 300 mg/m2, twice daily for Days 1-3; doxorubicin, 50 g/m2, on Day 4; vincristine, 2 mg, on Days 4 and 11; and dexamethasone, 40 mg, on Days 1-4 and Days 11-14), which also was given in odd-numbered consolidation Courses 3, 5, and 7. Even-numbered courses (Courses 2, 4, 6, and 8) were comprised of methotrexate, 200 mg/m2, over 2 hours followed by 800 mg/m2 over 24 hours on Day 1; cytarabine, 3 g/m2, every 12 hours for 4 doses over 2 days (Days 2 and 3); and intravenous methylprednisolone, 50 mg, twice daily on Days 1-3 (MTX/ara-C regimen). Two sequential treatment groups were assessable based on timing of the filgrastim administration; 151 patients received filgrastim starting on Day 5 (D5) of induction chemotherapy and 48 patients received filgrastim starting on Day 10 (D10). RESULTS: Time to neutrophil recovery was shorter for the D5 group than for the D10 group during induction chemotherapy (18 days vs. 19 days; P = 0.04) and hyper-CVAD Courses 3 and 5 (12 days vs. 15 days during Course 3, P < 0.001; and 13 days vs. 16 days during Course 5, P = 0.002). There was no apparent significant difference between the two groups with regard to time to neutrophil recovery during the MTX/ara-C courses or the last hyper-CVAD course. Delay in the administration of filgrastim did not appear to result in an increase in time to platelet count recovery or in the incidence of infection; however, there was an increased incidence of mucositis during induction chemotherapy. CONCLUSIONS: For a hyper-CVAD and MTX/ara-C regimen, the results of the current study have shown that the administration of filgrastim can be delayed until Day 10 without increasing the risk of treatment-related morbidity during consolidation chemotherapy. During induction chemotherapy, delay in the administration of filgrastim may result in a slight increase in the time to neutrophil count recovery and risk of mucositis, but there is no apparent associated increase in the risk of infection.
Adolescent↗
Albugranin, a recombinant human granulocyte colony stimulating factor (G-CSF) genetically fused to recombinant human albumin induces prolonged myelopoietic effects in mice and monkeys.
PURPOSE: Albugranin fusion protein is recombinant granulocyte colony stimulating factor (rG-CSF) genetically fused at its N-terminus to the C-terminus of recombinant serum human albumin and is expected to have a relatively long half-life compared with rG-CSF alone. In this study, the pharmacodynamics and pharmacokinetics of Albugranin were evaluated in BDF1 mice and cynomolgus monkeys. METHODS: Single doses of Albugranin (0.25-5 mg/kg) or Filgrastim (methionyl rG-CSF, 0.25, or 1.25 mg/kg) were administered subcutaneously (SC) to mice and multiple doses of Albugranin (25-100 microg/kg every 4 or 7 days) or Filgrastim (5 microg/kg daily) were administered SC for 14 days to monkeys for hematologic evaluation. For pharmacokinetics studies, mice were injected intravenously (IV) or SC with single doses of Albugranin (0.25-1.25 mg/kg) or Filgrastim (0.25 mg/ kg) and monkeys were injected SC with multiple doses of Albugranin (100-1,000 microg/kg once weekly for 5 weeks). Plasma levels of Albugranin and Filgrastim were measured by enzyme-linked immunosorbent assay. RESULTS: In mice, administration of Albugranin effectively increased the number of peripheral granulocytes and mobilized hematopoietic progenitor cells for up to 5 days. The magnitude and duration of this effect were dose-dependent. In contrast, administration of Filgrastim resulted in a small increase in both cell types on day 1 only. Albugranin administered to cynomolgus monkeys caused an increase in peripheral neutrophils, with a less prominent increase in peripheral monocytes. Albugranin-induced neutrophilia peaked 24 h following each dose administration. Administration of Filgrastim daily in monkeys resulted in moderate increases in neutrophils that were maximal on days 8-12 during the course of treatment. Compared with Filgrastim, Albugranin had a longer terminal half-life (t(1/2,term)) and mean residence time (MRT), and slower clearance (CL/F) in mice. The t(1/2,term), MRT, and CL/F of Albugranin following SC administration to BDF1 mice were 5.6-5.7 h, 16.7-20.7 h, and 6.37-12.2 mL/h/kg, respectively, compared with 2.54 h, 4.9 h, and 164 mL/h/kg, respectively for Filgrastim. In cynomolgus monkeys, the corresponding values of t(1/2,term), MRT, and CL/F for Albugranin were 7.73-133 h, 19.4-27.3 h, and 7.90-27.5 mL/h/kg, respectively, for doses of 100-1000 microg/kg. An exposure-response relationship that could be empirically described with a simple Emax model with baseline was found between day 15 absolute neutrophil count and area under the curve following the first dose in cynomolgus monkeys. CONCLUSION: The sustained activity of Albugranin in mice and monkeys demonstrated in these studies suggests that this agent could be given less frequently than Filgrastim to achieve similar therapeutic effects in patients.
Animals↗
Collection of two peripheral blood stem cell concentrates from healthy donors.
When peripheral blood stem cell (PBSC) concentrates are used for allogeneic transplants, two or more apheresis procedures must often be performed. To determine how many cells could be collected from healthy people by two back-to-back apheresis procedures and what effect these collections would have on donors, we gave 19 healthy people 5 micrograms kg-1 day-1 and 21 people 10 micrograms kg-1 day-1 of granulocyte colony stimulating factor, filgrastim, for 5 days. We then collected two PBSC concentrates, one on day 5 and one on day 6. A third group of six people was given filgrastim 10 micrograms kg-1 day-1 for 5 days but had no PBSC concentrates collected. PBSC concentrate cell counts and donor cell counts, symptoms, and blood chemistries were assessed for up to 1 year. On day 5, three times more CD34+ cells were collected from donors given 10 micrograms kg-1 day-1 than those given 5 micrograms kg-1 day-1 (P = 0.009) but on day 6 the quantity of cells collected was the same (P = 0.23). The total number of CD34+ cells collected was two times greater in donors given the higher dose of filgrastim (median = 579 x 10(6); range = 174-1639 x 10(6) compared to 237 x 10(6); 103-1670 x 10(6); P = 0.061). Platelet counts fell after each PBSC concentrate collection, but there were no differences between the two groups of donors in platelet counts measured immediately after each collection. The platelet counts also fell in people who did not donate PBSC concentrates. The lowest counts in all three groups of people also occurred on day 10. In PBSC donors given 10 micrograms kg-1 day-1 of filgrastim the absolute neutrophil count (ANC) fell below premobilization counts on day 14. In donors given 5 micrograms kg-1 day-1 the ANC fell below premobilization counts on days 21, 28 and 49, CD34+ cell counts were significantly lower than premobilization counts on days 14 and 28 in donors given 10 micrograms kg-1 day-1 of filgrastim and on day 14 in those given 5 micrograms kg-1 day-1. No decrease in neutrophil or CD34+ cell counts occurred after filgrastim was given in the people who did not donate PBSC concentrates. The incidence of symptoms was similar in both groups of PBSC concentrate donors, except that those given 10 micrograms kg-1 day-1 were more than twice as likely to experience myalgias as those receiving the lower dose (P = 0.029). Several blood chemistries changed. Levels of alkaline phosphatase, LDH, SGPT, SGOT, uric acid and sodium increased. Levels of bilirubin, total protein, potassium, calcium and chloride decreased. In conclusion, twice as many CD34+ cells were collected from donors given 10 micrograms kg-1 day-1 of filgrastim. Platelet, neutrophil and CD34+ cell counts fell after the PBSC concentrate collections. The fall in platelet counts was due to both the collection and the administration of filgrastim. The falls in neutrophil and CD34+ cell counts were due to the loss of haematopoietic progenitor cells in the PBSC concentrates. Allogeneic PBSC concentrate donors should be given 10 micrograms kg-1 day-1 of filgrastim, and if possible only one component should be collected in order to avoid thrombocytopenia.
Adult↗
Evidence that the granulocyte colony-stimulating factor (G-CSF) receptor plays a role in the pharmacokinetics of G-CSF and PegG-CSF using a G-CSF-R KO model.
The covalent attachment of polyethylene glycol to filgrastim results in a new molecule pegfilgrastim, which has a significantly longer half-life than filgrastim. It is likely that the clearance of both filgrastim and pegfilgrastim involves granulocyte colony simulating factor (G-CSF) receptor binding, but the pharmacokinetics of these drugs have not been compared in mice with and without a functional G-CSF receptor. We sought to clarify the role of receptor-mediated clearance of filgrastim and pegfilgrastim using wild-type (WT) mice or mice with a non-functional G-CSF-R (knockout, KO). We administered single doses of filgrastim or pegfilgrastim (10 or 100 microg kg(-1)) intravenously to WT and KO mice. Plasma levels of protein were measured by enzyme-linked immunosorbent assay (ELISA) at preset time points, and AUC, MRT, CL, V(d), and T(1/2) were calculated. When compared with WT mice, the G-CSF-R KO mice had significantly greater AUC, longer MRT, longer T(1/2), and lower clearance. This was the case whether animals received 10 or 100 microg kg(-1) and whether they received filgrastim or pegfilgrastim. The volume of protein distribution was identical among WT and KO mice. However, the V(d) was larger after pegfilgrastim dosing than after filgrastim dosing. In both WT and KO mice, increasing the dose of figrastim or pegfilgrastim resulted in a proportional increase in the AUC. A functional G-CSF-R is an important mechanism in the plasma clearance of both filgrastim and pegfilgrastim.
Animals↗
Once-per-cycle pegfilgrastim (Neulasta) for the management of chemotherapy-induced neutropenia.
Filgrastim (r-metHuG-CSF) was approved in the United States in 1991 for use in decreasing the incidence of infection, as manifested by febrile neutropenia, in patients with nonmyeloid malignancies treated with myelosuppressive chemotherapy. Colony-stimulating factors such as filgrastim are a significant advance in the supportive care of patients with cancer. However, because of its short half-life, filgrastim requires daily dosing by injection to maintain its effects on the bone marrow. Pegfilgrastim (Neulasta; Amgen, Thousand Oaks, CA) is a longer-acting, self-regulating form of filgrastim created by the covalent linkage of a 20-kd polyethylene glycol molecule to the N-terminal of the filgrastim molecule. The molecular characteristics of pegfilgrastim result in a longer terminal half-life, making once-per-chemotherapy-cycle administration possible. The results from two randomized double-blind phase III clinical trials in patients with breast cancer treated with myelosuppressive chemotherapy showed that a single dose of pegfilgrastim provides neutrophil support comparable with that provided by an average of 11 daily injections of filgrastim. Pegfilgrastim has also been shown to be comparable to filgrastim in reducing neutropenic complications in patients treated with chemotherapy for lymphoma. Data from three clinical trials have been presented: a randomized controlled trial in elderly patients treated with CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone) for relapsed or refractory non-Hodgkin's lymphoma; a randomized controlled trial in patients treated with ESHAP (etoposide/methylprednisolone/cisplatin/cytarabine) for relapsed or refractory lymphoma; and a study in patients with newly diagnosed non-Hodgkin's lymphoma. The safety profile of pegfilgrastim is comparable to that of filgrastim in the clinical settings studied to date. The once-per-cycle administration of pegfilgrastim may improve patient quality of life because it is less disruptive to patients and caregivers, and increase adherence because no doses are missed, thus further advancing the management of chemotherapy-induced neutropenia and its consequences.
Antineoplastic Agents↗
Phase I study of topotecan and cisplatin in patients with advanced solid tumors: a cancer and leukemia group B study.
PURPOSE: The objectives of this phase I trial were to determine the dose-limiting toxicities (DLTs) of the novel topoisomerase I inhibitor topotecan combined with cisplatin, to define the maximum-tolerated doses (MTDs) of the combination without and with the use of filgrastim, and to define recommended doses for phase II trials. PATIENTS AND METHODS: Patients with advanced solid tumors were eligible if they had normal bone marrow, renal, and hepatic function and had not previously been treated with platinum compounds. Topotecan was administered intravenously on days 1 through 5 and cisplatin was administered intravenously on day 1 of a 21-day cycle. The topotecan dose was fixed at 1.0 mg/m2/d on the first four dose levels, and cisplatin was escalated in 25-mg/m2 increments from 25 to 100 mg/m2 without filgrastim. After encountering DLT, the dose of cisplatin was decreased by one level and topotecan dose escalation was attempted. After defining the MTD without growth factor, the study proceeded with escalating cisplatin doses to define the MTD with filgrastim 5 micrograms/kg subcutaneously (SC) daily starting on day 6 of treatment. Priming with filgrastim 5 micrograms/kg SC on days -6 to -2 before the first course was explored last. RESULTS: Of 38 patients entered, 37 were eligible, 35 assessable for toxicity in the first course, and 28 assessable for response. The principal toxicity was grade 4 neutropenia, which had to last more than 7 days to be considered dose-limiting. No DLT was observed at the starting cisplatin dose of 25 mg/m2 (dose level 1). On level 2 (cisplatin 50 mg/m2, one patient had dose-limiting neutropenia and one patient had grade 3 renal toxicity. On level 3 (cisplatin 75 mg/m2), two patients had dose-limiting neutropenia. Therefore, cisplatin dose escalation was stopped. On dose level 5 (cisplatin 50 mg/m2 and topotecan 1.25 mg/m2/d), one patient had grade 4 neutropenia that lasted more than 7 days and one patient died of neutropenic sepsis. The remaining dose levels used topotecan 1.0 mg/m2/d plus cisplatin 75 mg/m2 (level 6) and 100 mg/m2 (levels 7 and 8) with filgrastim. No DLT was observed on level 6. On level 7, two patients had dose-limiting neutropenia and one patient had grade 3 hyperbilirubinemia. Priming with filgrastim on level 8 demonstrated no obvious advantage over level 7, and one patient had grade 4 thrombocytopenia that lasted more than 7 days. Three patients with non-small-cell lung cancer achieved a partial response and one patient with breast cancer had a complete response. CONCLUSION: Topotecan and cisplatin in combination cause more neutropenia than expected from either drug given alone at the same dosage. The recommended phase II doses are topotecan 1.0 mg/m2/d for 5 days in combination with cisplatin 50 mg/m2 on day 1 without filgrastim or cisplatin 75 mg/m2 on day 1 with filgrastim support.
Adult↗
Benefits of granulocyte-colony-stimulating factor after stem cell transfusion in intensive sequential chemotherapy for breast cancer.
The aim of this study was to evaluate the clinical and economic benefit of filgrastim given with intensive sequential chemotherapy. Women with poor-prognosis breast cancer received four cycles of high-dose cyclophosphamide (3 g/m2) and doxorubicin (75 mg/m2), followed by filgrastim 5 microg/kg/dy, stem cell collection after the cycle 1, and stem cell infusion after cycle 3 and cycle 4. The first cohort received filgrastim after the fourth cycle but the second cohort did not.Thirty three patients were included in the first cohort and 13 in the second. The results indicate that the duration of grade IV neutropenia was shorter in the group given filgrastim as was the median time to recover an absolute neutrophil count (ANC) > 1.0 x 10(9)/L. The rate and duration of the rehospitalizations were higher in the group not receiving filgrastim. We found that costs such as drugs and hospitalizations were significantly higher (p = 0.032 and p = 0.049) in the non-filgrastim-treated group. Using ANC > 1.0 x 10(9)/L as an intermediary efficiency criterion it was more cost effective to give filgrastim. It can be concluded from this study that filgrastim can decrease the duration of grade IV neutropenia in patients receiving intensive sequential chemotherapy. This, in turn, reduces the cost of hospitalization. However, in our study, this reduction of neutropenia did not have any impact on further therapy.
Adult↗
A predictive model for neutropenia associated with cancer chemotherapy.
Studies of primary prophylaxis of febrile neutropenia (FN) with recombinant human granulocyte colony-stimulating factor (rHu-G-CSF, filgrastim) administered to all patients starting their initial course of chemotherapy have demonstrated clinical effectiveness and an economic advantage in a wide range of settings. A recent meta-analysis confirmed the ability of filgrastim to reduce the risk of FN and documented infection in a variety of malignancies in both adults and children. The threshold risk for FN at which a cost saving is achieved by using filgrastim is inversely related to the daily cost of the drug and duration of hospitalization. Clinical practice guidelines for the use of filgrastim were developed based on these observations. Recent studies incorporating indirect institutional costs demonstrated that a cost saving can be achieved at substantially lower FN risk thresholds than previously estimated. Despite the demonstrated efficacy of filgrastim in primary prophylaxis, its value may be further increased by appropriately selecting patients and better understanding the importance of sustaining dose intensity in specific malignancies. Clinical prediction models capable of identifying individuals at high risk for neutropenic complications yield further reductions in FN risk thresholds and treatment costs in patients receiving cancer chemotherapy. These models also may be used to evaluate the cost-effectiveness or cost-efficiency of filgrastim. A clinical prediction model recently was presented and validated incorporating both baseline clinical characteristics as well as the results of the first cycle of chemotherapy in patients with early-stage breast cancer. A cost-effectiveness ratio of $34,297/year of life saved was estimated based on dose-response assumptions derived from a previously reported adjuvant breast cancer trial studying the impact of dose reduction on disease-free survival. The cost-effectiveness of filgrastim was evident over a wide range of clinical and cost assumptions. Clinical prediction models permit the rational and cost-effective identification of patients for filgrastim support. Existing clinical practice guidelines should be reevaluated in light of new information available on both the total costs associated with FN as well as the cost-effectiveness of these agents in patients receiving chemotherapy for sensitive and potentially curable malignancies.
Antineoplastic Agents↗
Comparison of the potency of glycosylated and nonglycosylated recombinant human granulocyte colony-stimulating factors in neutropenic and nonneutropenic CD rats.
Recent studies in human bone-marrow culture and healthy human volunteers suggest that lenograstim [glycosylated, recombinant human granulocyte colony-stimulating factor (rHuG-CSF) produced in Chinese hamster ovary (CHO) cells] has greater in vivo potency than filgrastim [nonglycosylated, methionine-extended recombinant human granulocyte colony-stimulating factor (rmetHuG-CSF) produced in Escherichia coli]. To confirm and extend these results we investigated the in vivo potency of both products in normal rats and neutropenic CD rats as an animal model of chemotherapy-induced neutropenia. In normal rats, groups of eight normal male CD rats received four subcutaneous doses of 10, 30, or 100 micrograms/kg filgrastim or lenograstim on days 1-4 of the study, whereas a control group received the vehicle. Blood samples were collected from each animal before treatment (day -5) and on days 2, 3, 5, 8, and 12 of the study for determination of red blood cell (RBC), platelet, white blood cell (WBC), and differential counts. rHuG-CSF and r-metHuG-CSF produced increased WBC counts, principally due to elevated absolute neutrophil counts (ANCs); on days 2, 3, and 5, all groups receiving rG-CSF had ANCs that increased in a progressive and dose-related manner. With the exception of a single value, mean ANCs obtained on days 2, 3, and 5 in lenograstim-treated groups were higher (statistically significant on day 3 at 30 and 100 micrograms/kg and on day 5 at 10, 30, and 100 micrograms/kg) than the respective values obtained in filgrastim-treated groups. No compound-related effect was noted in RBC or platelet parameters. Neutropenia was induced in male CD rats (12 animals/group) with a single intraperitoneal dose of 50 mg/kg cyclophosphamide (CPA) on day 0. On days 1-4, CPA-treated groups were treated with the vehicle (control) or with filgrastim or lenograstim at 30 or 100 micrograms/kg per day. An additional group was not treated with CPA and served as the absolute control group. Blood was collected from alternating subgroups on study day -5 (pretest) and on days 2, 3, 4, 5, 6, 8, 9, and 12 for determination of RBC, platelet, WBC, and differential counts. No major adverse in-life effect was noted in neutropenic rats. Maximal depression of WBCs and ANCs occurred on day 5, followed by recovery to normal values by days 9 (ANC) and 12 (WBC). On day 3 and days 5-9, rHuG-CSF- and metHuG-CSF-treated groups had marked and dose-related increases in WBCs as compared with CPA-treated controls, principally due to elevated ANCs. With the exception of a few values, mean ANC values obtained in lenograstim-treated groups were consistently higher than the respective values obtained in filgrastim-treated groups; the difference was statistically significant on day 3 (30-microgram/kg groups) and on days 6 and 8 (100-microgram/kg groups). In conclusion, treatment of normal and neutropenic CD rats with lenograstim resulted in a dose-related elevation of ANCs that was consistently and significantly higher than the response to identical doses of filgrastim. These results suggest that lenograstim, the glycosylated form of rG-CSF, has superior in vivo potency in normal and neutropenic animals as compared with filgrastim, the nonglycosylated form of rG-CSF.
Adjuvants, Immunologic↗
Phase I study of paclitaxel and etoposide for metastatic or recurrent malignancies.
The authors define the dose-limiting toxicities and the recommended phase II doses of paclitaxel combined with etoposide, without and with filgrastim support. Patients with advanced solid tumors were eligible if they had a performance status of 0 to 2 and normal renal, hepatic, and bone marrow function. Patients with cardiac arrhythmias or congestive heart failure requiring medical therapy were excluded. Prior radiation was allowed only if it involved less than 30% of the marrow-containing skeleton. The dose of etoposide was fixed at 100 mg/m2/d for 3 days beginning on day 1. Paclitaxel was administered over 3 hours on day 4. The dose of paclitaxel was escalated until the maximum tolerated dose (MTD), without and with filgrastim 5 microg/kg (or 300 microg total dose) subcutaneously beginning on day 5, was reached. Treatment cycles were repeated every 21 days. Of 39 patients entered, 37 were evaluable for toxicity and 30 for response. The principal toxicity was neutropenia. Without filgrastim, the MTD of paclitaxel was 150 mg/m2. With filgrastim, the dose of paclitaxel was escalated to 250 mg/m2 in combination with etoposide 100 mg/m2. One episode of pulmonary toxicity was observed. Five patients responded: two with previously treated non-small-cell lung cancer (NSCLC), two with refractory small-cell lung cancer (SCLC), and one with refractory germ-cell tumor (GCT). We conclude that paclitaxel and etoposide can be given in combination at clinically relevant doses with filgrastim support. In this phase I trial, a dose of paclitaxel of 200 mg/m2 on day 4 and etoposide at 100 mg/m2/d on days 1-3, with filgrastim 5 microg/kg beginning on day 5, was found to be well tolerated, and can be recommended for future studies. Without filgrastim, a paclitaxel dose of 150 mg/m2 with the same dose of etoposide can also be recommended.
Adult↗
The design and development of pegfilgrastim (PEG-rmetHuG-CSF, Neulasta).
Recombinant protein technology produces drugs for human therapy in unprecedented quantity and quality. Research is now focusing on the relationship between pharmacokinetic and pharmacodynamic properties of molecules, with the aim of engineering proteins that possess enhanced therapeutic characteristics in contrast to being used as simple replacements for the natural equivalent. The addition of a polyethylene glycol (PEG) moiety to filgrastim (rmetHu-G-CSF, Neupogen) resulted in the development of pegfilgrastim. Pegfilgrastim is a long-acting form of filgrastim that requires only once-per-cycle administration for the management of chemotherapy-induced neutropenia. The covalent attachment of PEG to the N-terminal amine group of the parent molecule was attained using site-directed reductive alkylation. Pegylation increases the size of filgrastim so that it becomes too large for renal clearance. Consequently, neutrophil-mediated clearance predominates in elimination of the drug. This extends the median serum half-life of pegfilgrastim to 42 hours, compared with between 3.5 and 3.8 hours for Filgrastim, though in fact the half-life is variable, depending on the absolute neutrophil count, which in turn reflects of the ability of pegfilgrastim to sustain production of those same cells. The clearance of the molecule is thus dominated by a self-regulating mechanism. Pegfilgrastim retains the same biological activity as filgrastim, and binds to the same G-CSF receptor, stimulating the proliferation, differentiation and activation of neutrophils. Once-per-chemotherapy cycle administration of pegfilgrastim reduces the duration of severe neutropenia as effectively as daily treatment with filgrastim. In clinical trials, patients receiving pegfilgrastim also had a lower observed incidence of febrile neutropenia than patients receiving filgrastim.
Animals↗