Economic evaluation of filgrastim, sargramostim, and sequential sargramostim and filgrastim after myelosuppressive chemotherapy

Increased mobilization and yield of stem cells using plerixafor in combination with granulocyte-colony stimulating factor for the treatment of non-Hodgkin's lymphoma and multiple myeloma

Multiple myeloma and non-Hodgkin’s lymphoma remain the most common indications for high-dose chemotherapy and autologous peripheral blood stem cell rescue. While a CD34+ cell dose of 1 × 10⁶/kg is considered the minimum required for engraftment, higher CD34+ doses correlate with improved outcome. Numerous studies, however, support targeting a minimum CD34+ cell dose of 2.0 × 10⁶/kg, and an “optimal” dose of 4 to 6 × 10⁶/kg for a single transplant. Unfortunately, up to 40% of patients fail to mobilize an optimal CD34+ cell dose using myeloid growth factors alone. Plerixafor is a novel reversible inhibitor of CXCR4 that significantly increases the mobilization and collection of higher numbers of hematopoietic progenitor cells. Two randomized multi-center clinical trials in patients with non-Hodgkin’s lymphoma and multiple myeloma have demonstrated that the addition of plerixafor to granulocyte-colony stimulating factor increases the mobilization and yield of CD34+ cells in fewer apheresis days, which results in durable engraftment. This review summarizes the pharmacology and evidence for the clinical efficacy of plerixafor in mobilizing hematopoietic stem and progenitor cells, and discusses potential ways to utilize plerixafor in a cost-effective manner in patients with these diseases.

Peripheral Blood Stem Cell Mobilization Tactics

OBJECTIVE

To evaluate the methods and collection techniques currently used in stem cell mobilization for patients undergoing autologous transplantation.

DATA SOURCES

Literature search was performed through PubMed (1948-August 2009) and MEDLINE (1977-August 2009). Reference citations from publications identified were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All literature identified was reviewed for inclusion. Original research and retrospective cohorts, along with previously published systematic reviews of stem cell mobilization and growth factors, were evaluated. Abstract data on plerixafor were also reviewed.

DATA SYNTHESIS

Successful mobilization of an adequate number of progenitor cells can help ensure and improve time to neutrophil and platelet engraftment. A variety of methods have been studied to find the safest and most predictable mobilization of CD34+ progenitor cells, including use of single agents or the combinations of hematopoietic growth factors, chemotherapy, and a novel chemokine receptor 4 antagonist. Currently, granulocyte colony-stimulating factor (G-CSF) 10 Mg/kg daily started 4 days prior to apheresis remains the standard of care for initial mobilization therapy. In patients who fail to mobilize or who are at high risk for mobilization failure, cyclophosphamide in conjunction with G-CSF may be used. Plerixafor, a novel chemokine receptor antagonist, in combination with G-CSF has demonstrated superiority for achieving collection goals compared to G-CSF alone in 2 Phase 3 trials.

CONCLUSIONS

The optimal mobilization strategy is still unknown; however, colony-stimulating factors remain the most commonly used mobilization agents. Currently, chemotherapy or plerixafor in combination with G-CSF is a reasonable option in heavily pretreated and hard-to-mobilize patients with non-Hodgkin's lymphoma and multiple myeloma.

Use of filgrastim for stem cell mobilisation and transplantation in high-dose cancer chemotherapy

Myeloablative or high-dose chemotherapy regimens utilise doses that are significantly greater than those used in standard treatments. The neutropenia caused by these high-dose therapies can be associated with an increased incidence of bacterial and fungal infections and remains an important clinical issue among patients with advanced-stage cancers. Filgrastim is approved for stem cell mobilisation in both chemotherapy-treated patients and normal donors. Harvested peripheral blood progenitor cells have been used effectively in allogeneic and autologous transplantation, increasing the speed and extent of neutrophil and platelet recovery. Accelerated haematopoietic recovery is associated with a significantly shorter hospital stay and, therefore, leads to a reduction in treatment costs. The contribution of filgrastim to the acceleration of haematopoietic recovery after peripheral blood progenitor cell transplant has been assessed in a number of prospective clinical trials after high-dose chemotherapy. Controversy remains over whether growth factors should be administered shortly after stem cell infusion or after several days. The recently approved, once-weekly form of filgrastim, pegfilgrastim, has been shown to have efficacy comparable to that of the native molecule and can be expected to enhance patient quality of life through the need for fewer injections. This article will review the role of filgrastim for stem cell mobilisation and transplantation in patients receiving high-dose chemotherapy.

Colony-stimulating factors for the management of neutropenia in cancer patients

Neutropenia and its subsequent infectious complications represent the most common dose-limiting toxicity of cancer chemotherapy. Febrile neutropenia (FN) occurs with common chemotherapy regimens in 25 to 40% of treatment-naive patients, and its severity depends on the dose intensity of the chemotherapy regimen, the patient's prior history of either radiation therapy or use of cytotoxic treatment, and comorbidities. The occurrence of FN often causes subsequent chemotherapy delays or dose reductions. It may also lengthen hospital stay, increase monitoring, diagnostic and treatment costs, and reduce patient quality of life. A decade after their introduction, colony-stimulating factors (CSFs) such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are now an integral part of the prevention of potentially life-threatening FN; however, only G-CSF has US Food and Drug Administration approval for use in chemotherapy-induced neutropenia. These adjunctive agents accelerate formation of neutrophils from committed progenitors, thereby reducing the duration and severity of neutropenia. Important uses of CSFs in oncology are prevention of FN after chemotherapy, treatment of febrile neutropenic episodes and support following bone marrow transplantation, and collection of CSF-mobilised peripheral blood progenitor cells. G-CSF is used more frequently than GM-CSF for all of these indications because of fewer associated adverse effects. Clinical trials to date have not demonstrated a significant effect on overall survival or disease-free survival, which is most likely to be due to small sample size and lack of power to prove effect. However, they have demonstrated clinical utility in allowing the delivery of planned chemotherapy dose on schedule, an important clinical goal especially in curative tumour settings. The high cost of these agents limits their widespread use. Current American Society of Clinical Oncology guidelines recommend primary prophylaxis, or first cycle use, with CSFs being confined to patients with > or = 40% risk of FN, which may include elderly patients and other high-risk patients. In addition to the risk of FN, primary prophylaxis should also be considered if the patient has risk factors that place them in the Special Circumstances category. These risk factors may include decreased immune function in patients who are already at an increased risk of infection and pre-existing neutropenia due to disease, extensive prior chemotherapy, or previous irradiation to the pelvis or other areas containing large amounts of bone marrow. Future studies are needed to better define the patients most likely to benefit from CSF therapy, both for prophylaxis and as an adjunct to antibiotics for treatment of FN. Other potential uses include combination therapy with stem cell factors and other cytokines to boost progenitor cell development, maintaining dose intensity of salvage therapy in metastatic cancer patients, and application in patients with pneumonia, Crohn's fistulas, diabetic foot infections and a variety of other infectious conditions.