A randomized double-blind multicenter phase III study of fixed-dose single-administration pegfilgrastim versus daily filgrastim in patients receiving myelosuppressive chemotherapy

Chemotherapy Dose Density in Early-Stage Breast Cancer and Non-Hodgkin’s Lymphoma

Delivering standard-dose chemotherapy on schedule is important for survival in early-stage breast cancer and non-Hodgkin's lymphoma. Trials of dose-escalated regimens, in which higher-than-standard doses of chemotherapy are used, have produced equivocal results. In contrast, dose-dense regimens, in which standard doses are given with shorter (usually 14-day) intervals between cycles, have been more efficacious than standard 21-day regimens in trials in both early-stage breast cancer and non-Hodgkin's lymphoma. Furthermore, a shorter course of chemotherapy is likely to cause less disruption in patients' lives. Despite the evidence of the importance of maintaining chemotherapy dose intensity (the amount of drug administered/unit of time), undertreatment of patients with early-stage breast cancer and non-Hodgkin's lymphoma is common. Neutropenia is the primary dose-limiting toxicity of many chemotherapy regimens, and it is frequently managed by dose reductions and delays that decrease dose intensity. Colony-stimulating factors reduce the prevalence and severity of neutropenia and its complications, and their proactive use can improve adherence to the planned schedule of both standard-dose and dose-dense chemotherapy The promising results with dose-dense chemotherapy in early-stage breast cancer and non-Hodgkin's lymphoma indicate that it should be tested in patients with other chemosensitive tumors.

Dose Density in Adjuvant Chemotherapy for Breast Cancer

BACKGROUND

Dose-dense chemotherapy increases the dose intensity of the regimen by delivering standard-dose chemotherapy with shorter intervals between the cycles. This article discusses the rationale for dose-dense therapy and reviews the results with dose-dense adjuvant regimens in recent clinical trials in breast cancer.

METHODS

The papers for this review covered evidence of a dose-response relation in cancer chemotherapy; the rationale for dose-intense (and specifically dose-dense) therapy; and clinical experience with dose-dense regimens in adjuvant chemotherapy for breast cancer, with particular attention to outcomes and toxicity.

RESULTS

Evidence supports maintaining the dose intensity of adjuvant chemotherapy within the conventional dose range. Disease-free and overall survival with combination cyclophosphamide, methotrexate, and fluorouracil are significantly improved when patients receive within 85% of the planned dose. Moderate and high dose cyclophosphamide, doxorubicin, and fluorouracil within the standard range results in greater disease-free and overall survival than the low dose regimen. The sequential addition of paclitaxel after concurrent doxorubicin and cyclophosphamide also significantly improves survival. Disease-free and overall survival with dose-dense sequential or concurrent doxorubicin, cyclophosphamide, and paclitaxel with filgrastim (rhG-CSF; NEUPOGEN) support are significantly greater than with conventional schedules (q21d).

CONCLUSIONS

The delivered dose intensity of adjuvant chemotherapy within the standard dose range is an important predictor of the clinical outcome. Prospective trials of high-dose chemotherapy have shown no improvement over standard regimens, and toxicity was greater. Dose-dense adjuvant chemotherapy improves the clinical outcomes with doxorubicin-containing regimens. Filgrastim support enables the delivery of dose-dense chemotherapy and reduces the risk of neutropenia and its complications.

Pegfilgrastim: a recent advance in the prophylaxis of chemotherapy-induced neutropenia

Chemotherapy-induced neutropenia is a frequent complication in cancer patients receiving myelosuppressive chemotherapy. Chemotherapy-induced neutropenia can result in febrile neutropenia and potentially life-threatening infections requiring hospitalization and intravenous anti-infectives. Chemotherapy dose may be reduced or delayed as a result of chemotherapy-induced neutropenia, which can negatively impact treatment outcomes. Granulocyte colony-stimulating factors, such as filgrastim, stimulate neutrophil production and can therefore reduce the incidence and severity of chemotherapy-induced neutropenia. Filgrastim undergoes rapid renal clearance and needs to be administered daily. The development of pegfilgrastim represents a significant advance in the management of chemotherapy-induced neutropenia as the longer serum half-life allows once-per-chemotherapy administration, and evidence supports increased prophylactic effectiveness in reducing the incidence of febrile neutropenia. This paper reviews the development of pegfilgrastim and summarizes recent clinical data on the use of this simple, effective and well-tolerated option for the management of chemotherapy-induced neutropenia in patients with cancer.

Neulasta (pegfilgrastim): a once-per-cycle option for the management of chemotherapy-induced neutropenia

Neutropenia is a significant hematologic complication induced by cytotoxic chemotherapy. The clinical consequences of chemotherapy-induced neutropenia are often severe and can be potentially life-threatening. Patients who develop febrile neutropenia often need to be hospitalized, reducing their quality of life and increasing costs. Neutropenia can also compromise the ability to deliver chemotherapy at the full dose and on schedule. To help prevent the occurrence of neutropenia, patients with a high risk of developing chemotherapy-related infections may be given prophylactic colony-stimulating factors. Filgrastim is a recombinant human granulocyte colony-stimulating factor that has been widely used (in over 3 million patients) for over 12 years in the management of neutropenia. Pegfilgrastim is an approved, long-acting, next generation of granulocyte colony-stimulating factor that has similar clinical benefits to filgrastim but has novel pharmacokinetic properties. Pegfilgrastim shows at least comparable safety and efficacy to filgrastim, with the added benefit of simplified once-per-chemotherapy-cycle dosing. In addition, two randomized, controlled pivotal trials have shown that a single dose of pegfilgrastim given once per cycle led to a lower observed incidence of febrile neutropenia following myelosuppressive chemotherapy, compared with daily injections of filgrastim. Clinical trials are currently expanding the clinical experience with pegfilgrastim in a variety of solid tumors and hematologic malignancies. In addition to prevention of chemotherapy-induced neutropenia in 21- and 28-day regimens, future studies are examining the suitability of pegfilgrastim in dose-dense therapy and other cancer settings.

Optimising management of neutropenia and anaemia in cancer chemotherapy-advances in cytokine therapy

Neutropenia and anaemia are serious complications of myelosuppressive chemotherapy. They have a negative impact on patient quality of life and may reduce response to treatment. Febrile neutropenia, a potentially life-threatening complication of neutropenia, frequently requires hospital admission, while fatigue and weakness from anaemia reduce patient's capacity for activity. Pegfilgrastim and darbepoetin alfa, were designed to simplify and optimise treatment for patients with cancer. Once-per-cycle pegfilgrastim is as effective as daily filgrastim with respect to duration of severe neutropenia (DSN) and may have a lower incidence of febrile neutropenia than filgrastim. Darbepoetin alfa has enhanced biological activity and a serum terminal half-life three-fold longer than that of erythropoietin (EPO), which translates into rapid and sustained correction of anaemia with less frequent dosing. These novel cytokines have the potential to simplify the management of neutropenia and anaemia with fewer injections and less disruption to patients daily lives.

Medical visits for chemotherapy and chemotherapy-induced neutropenia: a survey of the impact on patient time and activities

Background

Patients with cancer must make frequent visits to the clinic not only for chemotherapy but also for the management of treatment-related adverse effects. Neutropenia, the most common dose-limiting toxicity of myelosuppressive chemotherapy, has substantial clinical and economic consequences. Colony-stimulating factors such as filgrastim and pegfilgrastim can reduce the incidence of neutropenia, but the clinic visits for these treatments can disrupt patients' routines and activities.

Methods

We surveyed patients to assess how clinic visits for treatment with chemotherapy and the management of neutropenia affect their time and activities.

Results

The mean amounts of time affected by these visits ranged from approximately 109 hours (hospitalization for neutropenia) and 8 hours (physician and chemotherapy) to less than 3 hours (laboratory and treatment with filgrastim or pegfilgrastim). The visits for filgrastim or pegfilgrastim were comparable in length, but treatment with filgrastim requires several visits per chemotherapy cycle and treatment with pegfilgrastim requires only 1 visit.

Conclusions

This study provides useful information for future modelling of additional factors such as disease status and chemotherapy schedule and provides information that should be considered in managing chemotherapy-induced neutropenia.

The economics of the colony-stimulating factors in the prevention and treatment of febrile neutropenia

Healthcare costs continue to rise with hospitalization representing the single largest component of direct medical costs associated with cancer care. Neutropenia and its complications including febrile neutropenia remain the major dose-limiting toxicity associated with systemic cancer chemotherapy. Febrile neutropenia often occurs early in the course of chemotherapy and is associated with substantial morbidity, mortality and cost. The colony-stimulating factors (CSFs) have been used effectively in a variety of clinical settings to prevent or treat febrile neutropenia and to assist patients receiving dose-intensive chemotherapy. A meta-analysis of the available randomized controlled trials (RCTs) has confirmed the efficacy of prophylactic CSFs. Economic models based on measures of resource utilization derived from RCTs have provided estimates of expected treatment costs along with febrile neutropenia risk threshold estimates for the cost saving use of the CSFs. Recent studies have demonstrated the potential value of targeting the CSFs toward patients at greatest risk based on accurate and valid predictive models.

Open-label, randomized study of pegfilgrastim vs. daily filgrastim as an adjunct to chemotherapy in elderly patients with non-Hodgkin's lymphoma

Pegfilgrastim is composed of the protein filgrastim to which a 20-kDa polyethylene glycol (PEG) is covalently bound at the N-terminal residue resulting in decreased renal clearance and increased plasma half-life compared with filgrastim. This open-label, randomized, phase 2 study compared two doses of single administration pegfilgrastim (60 and 100 microg/kg) with daily doses of filgrastim (5 microg/kg/day) or no cytokine treatment after standard CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone) chemotherapy for non-Hodgkin's lymphoma in 50 elderly patients. The primary endpoint was the duration of grade 4 (severe) neutropenia (absolute neutrophil count < 0.5 x 10(9)/l) in cycle 1. Duration of grade 4 neutropenia in cycle 1 was 2.2 (SD 1.2), 1.5 (SD 1.1), 0.8 (1.2) and 5.0 (2.0) days for patients who received pegfilgrastim 60 microg/kg, pegfilgrastim 100 microg/kg, filgrastim 5 microg/kg and no cytokine, respectively. The baseline characteristics of the pegfilgrastim and filgrastim groups were imbalanced with increased bone-marrow involvement and prior therapy in the former. When the treatment groups were balanced for these risk factors, duration of grade 4 neutropenia was comparable with 2.0 and 3.0 vs. 0.6 and 0.5 days for pegfilgrastim 100 microg/kg and filgrastim patients with and without these risk factors, respectively. The incidence of febrile neutropenia (defined as ANC < 0.5 x 10(9)/l and temperature > 38.2degrees C) was low (10% of patients). Pegfilgrastim was well tolerated with a safety profile similar to daily filgrastim. Once per chemotherapy cycle administration of pegfilgrastim was comparable to filgrastim in this clinical setting.

Chemotherapy-induced neutropenia

Cytotoxic chemotherapy suppresses the hematopoietic system, impairing host protective mechanisms and limiting the doses of chemotherapy that can be tolerated. Neutropenia, the most serious hematologic toxicity, is associated with the risk of life-threatening infections as well as chemotherapy dose reductions and delays that may compromise treatment outcomes. The authors reviewed the recent literature to provide an update on research in chemotherapy-induced neutropenia and its complications and impact, and they discuss the implications of this work for improving the management of patients with cancer who are treated with myelosuppressive chemotherapy. Despite its importance as the primary dose-limiting toxicity of chemotherapy, much concerning neutropenia and its consequences and impact remains unknown. Recent surveys indicate that neutropenia remains a prevalent problem associated with substantial morbidity, mortality, and costs. Much research has sought to identify risk factors that may predispose patients to neutropenic complications, including febrile neutropenia, in an effort to predict better which patients are at risk and to use preventive strategies, such as prophylactic colony-stimulating factors, more cost-effectively. Neutropenic complications associated with myelosuppressive chemotherapy are a significant cause of morbidity and mortality, possibly compromised treatment outcomes, and excess healthcare costs. Research in quantifying the risk of neutropenic complications may make it possible in the near future to target patients at greater risk with appropriate preventive strategies, thereby maximizing the benefits and minimizing the costs.

The development of supportive-care agents for patients with cancer

As the population ages, a dramatic increase in the number of cases of cancer is expected and the need for supportive-care agents, those used to ameliorate some of the side effects of cancer or its treatment, becomes more urgent. At present, supportive-care products are available and new agents are being developed with novel mechanisms of action or modifications of existing agents that improve performance. Because of the urgent need for such products, efficient development is required to deliver useful products to patients as rapidly as possible. This chapter uses actual examples to illustrate the stages of drug development, phase I through phase 3.

Filgrastim-Mediated Neutrophil Recovery in Patients with Breast Cancer Treated with Docetaxel and Doxorubicin

STUDY OBJECTIVES

To study the impact of filgrastim 5 microg/kg given once/day through absolute neutrophil count (ANC) recovery on the duration of grade 4 neutropenia (ANC < 0.5 x 10(3)/mm3) and time to ANC recovery. Additional objectives were to study the average number of filgrastim injections/cycle required to achieve ANC recovery and differences in outcome by cycle.

DESIGN

Combined analysis of two double-blind, randomized, multicenter trials.

PATIENTS

Two hundred twenty-two patients treated for breast cancer.

MEASUREMENTS AND MAIN RESULTS

All patients but one were evaluable for efficacy end points. Mean +/- SD duration of grade 4 neutropenia was 1.7 +/- 1.3 days in cycle 1; the duration decreased in cycles 2-4 to between 1.0 and 1.2 days. Fifty percent of patients had ANC recovery to 10 x 10(3)/mm3 or greater by day 11 of the cycle, and 90% by day 13, corresponding to 10 and 12 days of filgrastim administration, respectively. Across all cycles, the mean +/- SD number of filgrastim injections/cycle was 10.51 +/- 1.70, with little variation among cycles.

CONCLUSION

When filgrastim is administered as recommended, starting 24 hours after chemotherapy and continuing through an ANC of 10 x 10(3)/mm3 or greater, neutrophil recovery is rapid and predictable. Because the first cycle of chemotherapy has the highest rates of neutropenia and febrile neutropenia, it seems prudent to administer growth factor support preemptively.

The impact of frequent injections for hematopoietic growth factor support on patients receiving chemotherapy: an observational study

BACKGROUND: Quality of life may be affected by daily injections of supportive hematopoietic growth factor medication, which is frequently required by patients with cancer undergoing chemotherapy. The objective of the study was to identify areas where long-acting derivatives of current proteins, which require less frequent administration, may provide advantages over existing therapies that require more frequent administration. METHODS: An observational study was conducted to assess the impact of daily injections of Filgrastim (NeupogencircledR;; Amgen Inc.) on patients' quality of life. A Subject Outcome Questionnaire was administered to patients after chemotherapy on 2 consecutive cycles. Time spent for treatment and patient attitude towards injection frequency were measured. The effect on patients' daily activities, including their ability to work, was analyzed. RESULTS: Thirty patients completed the first, and 24 the second, administration of the Questionnaire across 3 participating sites in the United States. The average patient time commitment for each daily injection was 78 minutes. Forty-five percent of patients were moderately to extremely bothered by travel during the first chemotherapy cycle, which increased to 59% during the second cycle. Forty-four percent and 18% of patients reported having to rearrange their daily schedules and take time off from work to accommodate each injection at least some of the time, respectively. Eighty-nine percent of the patients reported a preference for a longer-acting drug that required fewer injections. CONCLUSION: Results indicate that frequent injections represent a significant burden on patients' lives and that the majority would prefer longer-acting medications that require less frequent administration and potentially fewer clinic visits.

Safety and efficacy of pegfilgrastim in patients receiving myelosuppressive chemotherapy

The major dose-limiting toxicity associated with myelosuppressive chemotherapy is neutropenia, which can be ameliorated with proactive administration of granulocyte colony-stimulating factor (G-CSF). Pegfilgrastim is a long-acting G-CSF, recently approved by the Food and Drug Administration. The efficacy and safety of pegfilgrastim administered once/chemotherapy cycle have been evaluated in clinical trials involving patients treated with myelosuppressive chemotherapy for breast cancer, lung cancer, non-Hodgkin's lymphoma, and Hodgkin's disease. Two pivotal phase III trials in patients with breast cancer showed that pegfilgrastim is as effective as filgrastim regarding the primary efficacy end point, which was duration of grade 4 (severe) neutropenia in cycle 1 of myelosuppressive chemotherapy. Secondary end points were the frequency of fever with neutropenia (febrile neutropenia), duration of neutropenia in cycles 2-4, depth of the absolute neutrophil count (ANC) nadir, and time to ANC recovery in cycles 1-4. Once/cycle pegfilgrastim 100 microg/kg or 6 mg was as safe and effective as daily filgrastim 5 microg/kg in reducing the frequency and duration of severe neutropenia. A trend toward a greater reduction in the overall frequency of febrile neutropenia with pegfilgrastim was observed. The availability of pegfilgrastim simplifies the use of prophylactic G-CSF, with the potential to increase patient convenience and adherence in management of chemotherapy-induced neutropenia.

Pharmacokinetics of pegfilgrastim

Pegfilgrastim is a granulocyte colony-stimulating factor (G-CSF) with a long half-life and sustained duration of action. Pegfilgrastim is created with pegylation technology, whereby a 20-kD polyethylene glycol moiety is conjugated to filgrastim (recombinant human G-CSF), resulting in a larger molecule. Consequently, its renal clearance by glomerular filtration is minimized, making neutrophil-mediated clearance the predominant route of elimination. Preclinical animal data have shown that the clearance of pegfilgrastim depends on dosage and absolute neutrophil count, with pegfilgrastim having a longer circulating half-life and more sustained duration of action than filgrastim. The biologic effect of pegfilgrastim is prolonged in a neutropenic setting because few mature neutrophils are available to mediate its elimination. Clinical trials have suggested that neutrophil-mediated clearance of pegfilgrastim may be self-regulating and may therefore be specific to each patient's hematopoietic recovery.

Pegfilgrastim, a sustained-duration form of filgrastim, significantly improves neutrophil recovery after autologous marrow transplantation in rhesus macaques

Daily administration of filgrastim decreases the duration of severe neutropenia in the clinical setting. A sustained-duration form of filgrastim, pegfilgrastim, significantly reduces scheduling protocols to a single injection per chemotherapy cycle while maintaining therapeutic efficiency. We examined the ability of a single injection of pegfilgrastim to significantly improve neutrophil recovery following autologous bone marrow transplantation (AuBMT) in rhesus macaques. On day 1, postmyeloablation (920 cGy x-irradiation) and AuBMT, animals received either 0.1% autologous serum for 18 consecutive days (n=13), or single doses of pegfilgrastim via the subcutaneous (s.c.) or intravenous (i.v.) route (300 or 100 micro g/kg), or a single dose of filgrastim at 300 micro g/kg via the s.c. or i.v. route, or filgrastim at 10 micro g/kg via the s.c. route (n=4) on a daily basis (range=days 12-17). Pharmacokinetic parameters and neutrophil recovery were assessed. A single dose of pegfilgrastim via the i.v. or s.c. route was as effective as daily filgrastim administration, resulting in significant improvement of neutrophil recovery after myeloablation and ABuMT. Effective pegfilgrastim plasma concentrations were maintained in neutropenic animals until after the onset of hematopoietic recovery. Enhanced pharmacokinetics in AuBMT cohorts are consistent with self-regulating, neutrophil-mediated clearance.

Pegfilgrastim: using pegylation technology to improve neutropenia support in cancer patients

Pegylation of a protein can improve not only its formulation properties, but also both its pharmacokinetic and pharmacodynamic performance. Pegfilgrastim was made by linking a 20-kDa polyethylene glycol molecule to filgrastim, producing a long-acting cytokine requiring less frequent dosing than its parent drug. This review describes the clinical development of pegfilgrastim, and discusses its potential benefits to patients and caregivers in the prophylaxis of chemotherapy-induced neutropenia. Pegfilgrastim has a longer half-life and slower elimination rate than filgrastim, resulting in an increased serum concentration over time. Serum levels of pegfilgrastim are maintained until after a chemotherapy-induced neutrophil nadir and then decline rapidly as the neutrophil count recovers, consistent with a neutrophil-mediated clearance mechanism. In two pivotal phase III studies of women receiving chemotherapy for breast cancer, a single injection of pegfilgrastim per chemotherapy cycle, dosed either by body weight (100 microg/kg) or as a fixed dose (6 mg), was comparable to daily filgrastim (5 microg/kg) for all efficacy parameters, including duration of severe neutropenia and depth of neutrophil nadir. Analysis of pooled data from these studies showed a significantly lower incidence of febrile neutropenia in patients receiving pegfilgrastim compared with filgrastim (11 versus 19%, p<0.05), and a trend towards a lower risk of hospitalization and use of i.v. anti-infectives. The safety profiles of pegfilgrastim and filgrastim were similar. Pegfilgrastim given once per chemotherapy cycle is as effective and well tolerated as daily injections of filgrastim. With its more convenient dosing regimen, pegfilgrastim has the potential to improve quality of life and compliance in patients, and to be more cost effective.

Bone pain associated with once-per-cycle pegfilgrastim is similar to daily filgrastim in patients with breast cancer

Bone pain is a common side effect of treatment with filgrastim. Pegfilgrastim is a pegylated long-acting analogue of filgrastim that is administered once per chemotherapy cycle. The profile of prospectively defined, patient-reported bone pain judged by the investigators as related to study drug was analyzed retrospectively for each drug using data from two comparable phase III trials. These multicenter, randomized, double-blind, noninferiority trials compared once-per-cycle pegfilgrastim (6 mg, study 1 or 100 microg/kg, study 2) to daily filgrastim 5 microg/kg in patients with stage II-IV breast cancer undergoing multiple cycles of myelosuppressive chemotherapy (doxorubicin/docetaxel). Subcutaneous once-per-cycle pegfilgrastim 6-mg and 100-microg/kg doses were administered to 76 and 150 patients, respectively; subcutaneous daily filgrastim 5 microg/kg was administered to a total of 227 patients. Because bone pain in study 1 was higher (P = 0.044) in every cycle compared with study 2, all analyses were performed separately for each study. No statistically significant differences in incidence, severity, or duration were observed between patients receiving either once-per-cycle pegfilgrastim or daily filgrastim in either study. Bone pain incidence and severity were significantly greater (P < 0.001) in cycle 1 of both studies compared with later cycles. Among patients with bone pain, a trend towards earlier onset with pegfilgrastim was observed but was not associated with increased bone pain severity or duration. In patients who received a fixed 6-mg dose of pegfilgrastim, the overall bone pain incidence was similar when analyzed by body weight (< 60 kg, 60-100 kg, > 100 kg). No patients were withdrawn from either study for bone pain.