Treatment with Plerixafor in non-Hodgkin's Lymphoma and Multiple Myeloma Patients to Increase the Number of Peripheral Blood Stem Cells When Given a Mobilizing Regimen of G-CSF: Implications for the Heavily Pretreated Patient

How I treat patients who mobilize hematopoietic stem cells poorly

Transplantation with 2-5 × 106 mobilized CD34+cells/kg body weight lowers transplantation costs and mortality. Mobilization is most commonly performed with recombinant human G-CSF with or without chemotherapy, but a proportion of patients/donors fail to mobilize sufficient cells. BM disease, prior treatment, and age are factors influencing mobilization, but genetics also contributes. Mobilization may fail because of the changes affecting the HSC/progenitor cell/BM niche integrity and chemotaxis. Poor mobilization affects patient outcome and increases resource use. Until recently increasing G-CSF dose and adding SCF have been used in poor mobilizers with limited success. However, plerixafor through its rapid direct blockage of the CXCR4/CXCL12 chemotaxis pathway and synergy with G-CSF and chemotherapy has become a new and important agent for mobilization. Its efficacy in upfront and failed mobilizers is well established. To maximize HSC harvest in poor mobilizers the clinician needs to optimize current mobilization protocols and to integrate novel agents such as plerixafor. These include when to mobilize in relation to chemotherapy, how to schedule and perform apheresis, how to identify poor mobilizers, and what are the criteria for preemptive and immediate salvage use of plerixafor.

[Hematopoietic stem cells mobilization: state of the art in 2011 and perspectives]

High-dose chemotherapy with stem cells support has largely improved in terms of hematopoietic stem and progenitor cells harvest procedures as well as in those, which target or manipulate the cellular composition of autologous graft. Optimal preparative regimens and supportive care had lead to better use of autologous transplantation procedure. For other patients assigned to hematopoietic transplantation, availability of allogeneic donors appears to be an interesting alternative source of hematopoietic stem cells. Since three decades, hematopoietic growth factors development has allowed mobilization optimization and collection of peripheral hematopoietic stem cells leading to reduced days of hospitalization and less blood products requirements, being more cost-effective for patients in autologous transplantation settings and for stem cell collection facilities in allogeneic ones. New perspectives include, besides ex vivo manipulation of graft, development of mobilizing drugs in order to perform transplantation even in poor mobilizers patients. An important goal is achieved with the description of genetic polymorphisms related to optimal mobilization of stem cells. New approach using more promising and selective agents called chemokines, such as plerixafor the main leader among these agents are now available and appear complementary for alternative approach using cytokines alone (G-CSF, GM-CSF, SCF). The aim of this review is to assess the evolution of theses biotechnologies and their role in different steps of autologous transplantation and allogeneic stem cells collection.

Limiting the daily total nucleated cell dose of cryopreserved peripheral blood stem cell products for autologous transplantation improves infusion-related safety with no adverse impact on hematopoietic engraftment

Cryopreserved peripheral blood stem cell (PBSC) products can induce a number of infusion-related adverse reactions, including life-threatening cardiac, neurologic, and other end-organ complications. Preliminary analyses suggested limiting the daily total nucleated cell dose infused might decrease the incidence of these adverse effects. A policy change implemented in December 2007, limiting the total nucleated cell (TNC) dose to <1.63 × 10(9) TNC/kg/day, allowed us to assess the impact of this intervention on infusion-related safety, infusion schedules, engraftment, and costs in cohorts of patients undergoing autologous stem cell transplants (ASCTs) 2 years before (325 ASCTs in 288 patients) and 2 years after the policy change (519 ASCTs in 479 patients). The percentage of autologous transplant patients requiring multiple day infusions increased from 6% to 24%. Concurrently, the incidence of infusion-related grade 3-5 severe infusion-related adverse events (SAEs) decreased significantly, from 4% (13 of 325) prepolicy change to 0.6% (3 of 519) postpolicy change (P < .0004). Multiday infusions were not associated with increased time to neutrophil or platelet engraftment or the costs of transplantation. We conclude that limiting the daily TNC dose improved the safety of this procedure without compromising engraftment or increasing the costs of the procedure.

In and out of the niche: perspectives in mobilization of hematopoietic stem cells

Several stem cell mobilization strategies have been employed in the past 2 decades, including chemotherapy, hematopoietic growth factors, and chemotherapy plus growth factors. Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage CSF are standard agents approved for peripheral blood stem cell mobilization since the early 1990s. Between 5% and 20% of patients, however, fail to mobilize a sufficient numbers of peripheral blood stem cells in response to G-CSF with or without chemotherapy. Recent advances in defining the basic mechanisms regulating the interactions between hematopoietic stem cells and their marrow niche had led to the discovery that CXCR4 and stromal-cell-derived factor 1α axis play a significant role. Plerixafor, an antagonist of the CXCR4-stromal-cell-derived factor 1α axis has been shown to result in a significant mobilization of hematopoietic stem cells. Numerous clinical trials have demonstrated that the combination of G-CSF and AMD3100 (G+A) resulted in a significant increase in CD34(+) cell yield as compared to the administration of G-CSF alone. In particular, the progenitors mobilized have been shown to comprise a significantly higher proportion of primitive and possibly more potent CD34(+)/CD38(-) subpopulation. Transplantation of PBSC mobilized by G+A administration have led to a rapid and sustained neutrophil and platelet engraftment. Another prospective role of this new class of agents might lie in the mobilization of dormant leukemia stem cells that are well protected by the niche. The future role of CXCR4 antagonists in treatment of hematologic malignancies includes mobilization of hematopoietic stem cells for transplantation and mobilization of leukemia-initiating cells for long-term cure.

Plerixafor for autologous CD34 cell mobilization

High-dose chemotherapy and autologous transplantation of hematopoietic cells is a crucial treatment option for hematologic malignancy patients. Current mobilization regimes often do not provide adequate numbers of CD34(+) cells. The chemokine receptor CXCR4 and ligand SDF-1 are integrally involved in homing and mobilization of hematopoietic progenitor cells. Disruption of the CXCR4/SDF-1 axis by the CXCR4 antagonist, plerixafor, has been demonstrated in Phase II and Phase III trials to improve mobilization when used in conjunction with granulocyte colony-stimulating factor (G-CSF). This approach is safe with few adverse events and produces significantly greater numbers of CD34(+) cells when compared to G-CSF alone. New plerixafor initiatives include use in volunteer donors for allogeneic hematopoietic cell transplant and in other disease targets.

Plerixafor mobilization leads to a lower ratio of CD34+ cells to total nucleated cells which results in greater storage costs

BACKGROUND

Plerixafor (Mozobil, AMD3100) with granulocyte-colony stimulating factor (G-CSF) mobilizes more CD34+ cells/kg compared to G-CSF alone. Given that plerixafor enhances mobilization of multiple white blood cell lineages, we determined if more storage space is required for products collected from patients mobilized with plerixafor.

METHODS

A review of the medical records of 15 patients mobilized with chemotherapy and G-CSF (control) and 14 patients mobilized with plerixafor plus G-CSF (plerixafor) was performed. Data on demographics, baseline characteristics, CD34+ cells/kg, total nucleated cells, total mononuclear cells, total apheresis sessions, and total bags for storage were collected. Mean values were determined and compared using Student's t-test.

RESULTS

We found that the proportion of CD34+ cells among total nucleated cells was less in the plerixafor group compared to the control group (P = 0.0427). More nucleated cells (10.7 x 10(10) vs. 7.1 x 10(10), P =0.0452) and mononuclear cells (9.7 x 10(10) vs. 5.9 x 10(10), P = 0.0059) were mobilized with plerixafor plus G-CSF. However, there was no significant difference in CD34+ cells/kg, total CD34+ cells or the proportion of mononuclear cells among total nucleated cells between the two groups. More storage bags were required for the plerixafor group compared to the control group (15 vs. 9, P = 0.0299).

CONCLUSION

Mobilization with plerixafor plus G-CSF resulted in a smaller proportion of CD34+ cells collected and a greater number of storage bags. An increase in the number of bags required for stem cell storage may be logistically problematic and will also lead to increased costs for storage of stem cells.

Current status of stem cell mobilization

New advances in effective mobilization of peripheral blood stem cells have permitted a greater proportion of patients to benefit from autologous stem cell transplantation. In this review, the relative merits of peripheral blood and mobilized bone marrow are discussed. All available agents are reviewed. A critical assessment of the appropriate dosing and frequency of available growth factors is undertaken, and the most commonly used chemotherapy plus growth factor combinations are covered. Specific recommendations for patients who are poor mobilizers are dealt with including the role of plerixafor.

Ancestim (r-metHuSCF) plus filgrastim and/or chemotherapy for mobilization of blood progenitors in 513 poorly mobilizing cancer patients: the French compassionate experience

Ancestim (r-MetHuSCF) is available in France for compassionate use in patients who are candidates for high-dose chemotherapy and autologous transplantation, and who failed in previous attempts at mobilization and collection. We report here data from 513 adult patients who benefited from this program, between January 1998 and July 2007. Given with systematic premedication, ancestim was generally well tolerated, although severe but not life-threatening adverse events were reported in 12 individuals. Overall, a graft was obtained or completed for 235 patients (46%). The median number of collected CD34+ cells was 3.00 × 10(6)/kg (range: 0.03-39.50). The target threshold of 2 × 10(6) CD34+ cells/kg was reached in 161 patients (31%). Factors associated with collection were diagnosis of myeloma, no previous autologous transplant, no more than one previous failed attempt and a mobilization regimen including cytotoxic agents. A total of 207 patients (40%) proceeded to high-dose chemotherapy and autologous transplantation. The median time to reach 0.5 × 10(9)/L neutrophils and 20 × 10(9)/L platelets was 12 (6-40) and 13 (0-31) days, respectively. We conclude that a combination of ancestim with filgrastim successfully mobilized CD34+ cells in peripheral blood, and allowed adequate collection in preparation for autologous transplantation in approximately one-third of poorly mobilizing patients.

Hematopoietic stem cell mobilization with the reversible CXCR4 receptor inhibitor plerixafor (AMD3100)-Polish compassionate use experience

Recent developments in the field of targeted therapy have led to the discovery of a new drug, plerixafor, that is a specific inhibitor of the CXCR4 receptor. Plerixafor acts in concert with granulocyte colony-stimulating factor (G-CSF) to increase the number of stem cells circulating in the peripheral blood (PB). Therefore, it has been applied in the field of hematopoietic stem cell mobilization. We analyzed retrospectively data regarding stem cell mobilization with plerixafor in a cohort of 61 patients suffering from multiple myeloma (N = 23), non-Hodgkin’s lymphoma (N = 20), or Hodgkin’s lymphoma (N = 18). At least one previous mobilization attempt had failed in 83.6% of these patients, whereas 16.4% were predicted to be poor mobilizers. The median number of CD34+ cells in the PB after the first administration of plerixafor was 22/μL (range of 0–121). In total, 85.2% of the patients proceeded to cell collection, and a median of two (range of 0–4) aphereses were performed. A minimum of 2.0 × 10⁶ CD34+ cells per kilogram of the patient’s body weight (cells/kg b.w.) was collected from 65.6% of patients, and the median number of cells collected was 2.67 × 10⁶ CD34+ cells/kg b.w. (0–8.0). Of the patients, 55.7% had already undergone autologous stem cell transplantation, and the median time to neutrophil and platelet reconstitution was 12 and 14 days, respectively. Cases of late graft failure were not observed. We identified the diagnosis of non-Hodgkin’s lymphoma and previous radiotherapy as independent factors that contributed to failure of mobilization. The current report demonstrates the satisfactory efficacy of plerixafor plus G-CSF for stem cell mobilization in heavily pre-treated poor or predicted poor mobilizers.

Chemokines as therapeutic targets for atherosclerotic plaque destabilization and rupture

Chemokines are instrumental in the initiation and progression of atherosclerosis. Recent advances in genomic technologies and the recognition of atherosclerosis as an inflammatory disease have given great impetus to studies addressing the relevance of chemokines for the clinically manifest stages of atherosclerosis and acute cardiovascular syndromes. In this paper, we will review the current status of these studies, highlighting those chemokines that have already been associated with plaque destabilization and rupture. We will recapitulate recent epidemiologic, genomic, histopathological and experimental support for the prominent role of particular chemokines in acute cardiovascular syndromes. Collectively, these data underpin the potential of chemokines as biomarkers and/or therapeutic targets, but also expose the lacunae in our understanding of the precise function of chemokines in the atherosclerosis-related disorders and in the efficacy of chemokine-targeted clinical trials.

Update on clinical experience with AMD3100, an SDF-1/CXCL12-CXCR4 inhibitor, in mobilization of hematopoietic stem and progenitor cells

PURPOSE OF REVIEW

Mobilized peripheral blood stem cells are increasingly used for the reconstitution of hematopoiesis in autologous and allogeneic transplants. New agents and approaches are emerging to improve mobilization efficacy while reducing duration and toxicity of mobilization. The purpose of this review is to overview clinical experience with AMD3100 (plerixafor) and its role in stem cell mobilization.

RECENT FINDINGS

AMD3100 is a bicyclam molecule that selectively and reversibly antagonizes the binding of stromal cell-derived factor-1 (SDF-1) to its receptor CXC motif receptor-4 (CXCR4) with subsequent egress of hematopoietic stem cells to the peripheral blood. AMD3100 safely and rapidly mobilizes stem cells in patients with lymphoma, myeloma and healthy donors, and is synergistic in combination with granulocyte-colony stimulating factor. In addition, AMD3100 disrupts the interaction between mouse and human leukemic blasts and the bone marrow stroma, mobilizing blasts to the peripheral blood and sensitizing them to chemotherapy.

SUMMARY

AMD3100 was recently FDA-approved for stem cell mobilization in combination with granulocyte-colony stimulating factor in patients with non-Hodgkin's lymphoma and multiple myeloma. Studies are underway testing AMD3100 as an adjunct to chemotherapy in patients with refractory acute myelogenous leukemia (and other hematologic malignancies), as a strategy to sensitize leukemic cells to chemotherapy and improve clinical outcomes.

Recent advances on the use of the CXCR4 antagonist plerixafor (AMD3100, Mozobil™) and potential of other CXCR4 antagonists as stem cell mobilizers

AMD3100 was originally discovered as an anti-HIV agent effective in inhibiting the replication of HIV in vitro at nanomolar concentrations. We found it to be a potent and selective antagonist of CXCR4, the receptor for the chemokine SDF-1 (now called CXCL12). AMD3100 was then developed, and marketed, as a stem cell mobilizer, and renamed plerixafor (Mozobil™). The path to the discovery of Mozobil™ as a stem cell mobilizer was described in Biochem. Pharmacol. 77: 1655-1664 (2009). Here I review the recent advances that have consolidated the role of plerixafor in mobilizing hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) from the bone marrow into the blood circulation. Plerixafor acts synergistically with granulocyte colony-stimulating factor (G-CSF), and its usefulness has been proven particularly for the mobilization of HSCs and HPCs for autologous stem cell transplantation in patients with non-Hodgkin's lymphoma (NHL) or multiple myeloma (MM). Plerixafor also has great potential for the treatment of hematological malignancies other than NHL and MM, and non-hematological malignancies, and, eventually, several other diseases depending on the CXCL12-CXCR4 interaction. Various AMD3100 analogs have been described (i.e. AMD11070, AMD3465, KRH-3955, T-140, and 4F-benzoyl-TN14003), primarily as potential anti-HIV agents. They are all strong CXCR4 antagonists. Their role in stem cell mobilization remains to be assessed.

Plerixafor (Mozobil) for stem cell mobilization in patients with multiple myeloma previously treated with lenalidomide

Lenalidomide and other new agents have considerable activity in multiple myeloma (MM) and have changed the landscape of treatment. Data suggest that lenalidomide therapy before autologous hematopoietic stem cell transplantation has a detrimental effect on stem cell mobilization. This retrospective study examined the efficacy of plerixafor in combination with G-CSF among patients with MM previously treated with lenalidomide (median, 4 cycles; range, 1-20 cycles). Data were analyzed for 60 patients who received plerixafor plus G-CSF for frontline mobilization in a phase 3 clinical trial or an expanded access program (n=20) or for remobilization in a compassionate use program (n=40). The overall median number of CD34+ cells collected was 5.6 × 10(6) per kg (range, 0.45 × 10(6)-37.2 × 10(6)). The minimum number of CD34+ cells (2 × 10(6) per kg) was collected from 86.7% of patients in a median of 1 day. This minimum was collected from 100% of patients who underwent frontline mobilization and 80% of patients who underwent remobilization. These data suggest that CD34+ hematopoietic stem cells can be successfully and predictably collected with combination plerixafor plus G-CSF for primary or secondary mobilization in the majority of patients with MM who have been previously treated with lenalidomide.

Development and validation of a decision-making algorithm to guide the use of plerixafor for autologous hematopoietic stem cell mobilization

Plerixafor is an inhibitor of CXCR-4 (CXC chemokine receptor-4)/SDF (stromal cell-derived factor)-1 binding used in combination with granulocyte colony-stimulating factor (G-CSF) for mobilization of autologous peripheral blood hematopoietic stem cells (HSCs). We developed a data-generated, cost-saving decision-making algorithm that uses the CD34+ count in the peripheral blood on the fourth day of G-CSF administration (PB-CD34+), and the collection target (T-CD34+) to decide between continuing G-CSF only (G approach) or adding plerixafor to the mobilization regimen (G+P approach) aiming at the lowest cost. The G+P approach was more cost-effective with lower PB-CD34+. It was possible to determine, for each T-CD34+, the maximum PB-CD34+ for which the G+P approach is cost-effective, generating an algorithm for the use of plerixafor. We validated this algorithm in a cohort of 34 patients undergoing HSC mobilization. In all, 11 patients completed collection on the G approach and 23 patients on the G+P approach, with 91% of the patients completing collection within the predicted number of apheresis sessions. All patients who underwent transplantation engrafted with minimal differences in engraftment time between G and G+P approaches. This validated algorithm provides a potential cost-saving decision tool for the use of plerixafor in autologous HSC mobilization.

Plerixafor for Stem Cell Mobilization Prior to Autologous Stem Cell Transplant in Non-Hodgkin's Lymphoma and Multiple Myeloma

Objective:

To review the pharmacology, pharmacokinetics, dosage, administration, clinical efficacy, safety, and place in therapy of plerixafor, a CXCR4 receptor antagonist used to mobilize stem cells prior to hematopoietic stem cell transplantation.

Data Sources:

Articles were identified by searching MEDLINE (1950-August 2009) and the American Society of Hematology abstract database using the key terms plerixafor, AMD3100, hematopoietic stem cell transplant, mobilization, multiple myeloma, and non-Hodgkin's lymphoma. Additional articles were obtained by using the reference sections of articles found during the literature search.

Study Selection and Data Extraction:

All articles identified from the literature search were reviewed for relevant information. Appropriate information was included in this review. The search was restricted to available English-language articles, including those on both preclinical and clinical trials.

Data Synthesis:

Plerixafor is a CXCR4 receptor antagonist approved by the FDA to assist in the mobilization of hematopoietic stem cells in patients with non-Hodgkin's lymphoma or multiple myeloma undergoing autologous stem cell transplant. Plerixafor is used in combination with granulocyte colony-stimulating factor. Plerixafor has been compared with placebo in both Phase 2 and Phase 3 clinical trials and has been shown to allow for a greater collection of hematopoietic stem cells in fewer apheresis sessions. Plerixafor demonstrated good tolerability in clinical trials.

Conclusions:

Plerixafor has demonstrated efficacy and tolerability when used for stem cell mobilization in patients with non-Hodgkin's lymphoma and multiple myeloma. Further studies are warranted to determine the safety and efficacy of plerixafor in patients with malignancies other than non-Hodgkin's lymphoma or multiple myeloma who are undergoing stem cell transplant and to determine its potential use in healthy stem cell donors.

Comparison of unmobilized and mobilized graft characteristics and the implications of cell subsets on autologous and allogeneic transplantation outcomes

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) are considered the standard of care for many malignancies, including lymphoma, myeloma, and some leukemias. In many cases, mobilized peripheral blood has become the preferred source of hematopoietic stem cells. The efficacy of different mobilization regimens and transplantation outcomes based on cell doses has been well studied; however, the characteristics of the stem cell graft may be of equal importance with respect to patient outcomes following autologous or allogeneic HSCT. This review summarizes available preclinical and clinical data for bone marrow and mobilized peripheral blood HSCT characteristics, defined as the cell types found in the graft as well as their gene expression profiles. It also explores how graft characteristics can affect bone marrow homing, engraftment, immune reconstitution, and other posttransplantation outcomes in both the allogeneic and autologous HSCT settings.

Clinical impact and resource utilization after stem cell mobilization failure in patients with multiple myeloma and lymphoma

High-dose chemotherapy in conjunction with auto-SCT is the preferred treatment of relapsed Hodgkin disease and non-Hodgkin lymphoma and newly diagnosed multiple myeloma. Failure to achieve optimal stem cell mobilization results in multiple subsequent attempts, which consumes large amounts of growth factors and potentially requires antibiotics and transfusions. We retrospectively reviewed the natural history of stem cell mobilization attempts at our institution from 2001 to 2007 to determine the frequency of suboptimal mobilization in patients with hematologic malignancy undergoing autologous transplant and analyzed the subsequent resource utilization in patients with initially failed attempts. Of 1775 patients undergoing mobilization during the study period, stem cell collection (defined by the number of CD34+ cells/kg) was 'optimal' (> or = 5 x 10(6)) in 53%, 'low' (> or = 2-5 x 10(6)) in 25%, 'poor' (<2 x 10(6)) in 10%, and 'failed' (<10 CD34+ cells/microl) in 12%. In the 47% of collections that were less than optimal, increased resource consumption included increased use of growth factors and antibiotics, subsequent chemotherapy mobilization, increased transfusional support, more apheresis procedures, and more frequent hospitalization. This usually unappreciated resource utilization associated with stem cell mobilization failure highlights the need for more effective mobilization strategies.

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.

CXCR4 in clinical hematology

Pharmacological manipulation of CXCR4 has proven clinically useful for mobilization of stem and progenitor cells and in several preclinical models of disease. It is a key component in the localization of leukocytes and stem cells. For patients with multiple myeloma and non-Hodgkin's Lymphoma, treatment with plerixafor, an inhibitor of CXCL12 binding to CXCR4, plus G-CSF mobilizes stem cells for autologous transplantation to a greater degree than the treatment with G-CSF alone, and in some cases when patients could not be mobilized with cytokines, chemotherapy, or the combination. Stem cells from healthy donors mobilized with single agent plerixafor have been used for allogeneic transplantation in acute myelogenous leukemia (AML) patients, although this is still in the early phase of clinical development. Plerixafor is also undergoing evaluation to mobilize tumor cells in patients with AML and chronic lymphocytic leukemia (CLL) to enhance the effectiveness of chemotherapy regimens. Plerixafor's effect on neutrophils may also restore circulating neutrophil counts to normal levels in patients with chronic neutropenias such as in WHIMs syndrome. Other areas where inhibition of CXCR4 may be useful based upon preclinical or clinical data include peripheral vascular disease, autoimmune diseases such as rheumatoid arthritis, pulmonary inflammation, and HIV.

Haematopoietic stem cell transplantation: current concepts and novel therapeutic strategies

INTRODUCTION

Haematopoietic stem cell transplantation (HSCT) is potentially curative for haematological diseases. New developments are improving its applicability and success. Sources of data A literature search was conducted on peripheral blood haematopoietic stem cell (PBHSC) mobilization, umbilical cord blood (UCB) transplantation, reduced intensity conditioning (RIC) and acute graft-versus-host disease (aGVHD).

AREAS OF AGREEMENT

PBHSC mobilization by granulocyte colony-stimulating factor and chemomobilization may fail in up to 30% of patients previously treated with extensive chemotherapy. New mobilization agents, notably the CXCR4 antagonist, have improved mobilization efficacy. UCB-HSCT is equally feasible in children and adults. RIC enables HSCT to be performed in patients who are elderly or with serious medical co-morbidities. RIC-HSCT is associated with increased frequency of graft failure and disease relapse. The prophylaxis and treatment of aGVHD are still problematic.

AREAS OF CONTROVERSY

Novel strategies in PBHSC mobilization, utilization of UCB-HSCT and RIC-HSCT and prophylaxis and treatment of aGVHD, have not been critically appraised or compared with conventional strategies.

AREAS TIMELY FOR DEVELOPING RESEARCH

The safety and efficacy of novel mobilization agents have to be tested in normal allogeneic donors. Methods of increasing the cell dose or efficacy of UCB should be developed, to extend its use to adults. RIC-HSCT should be compared with conventional HSCT in young patients. Continuous efforts in defining the best prophylaxis and treatment of aGVHD should be made.

Plerixafor for stem cell mobilization in patients with non-Hodgkin's lymphoma and multiple myeloma

OBJECTIVE

To evaluate the literature characterizing the mechanism of action, pharmacokinetics, pharmacodynamics, and therapeutic efficacy of plerixafor for hematopoietic stem cell (HSC) mobilization for autologous transplantation in patients with non-Hodgkin's lymphoma (NHL) or multiple myeloma.

DATA SOURCES

A PubMed search (1966-September 2009) was conducted using the key words plerixafor and AMD3100. Manufacturer's prescribing information was also used.

STUDY SELECTION AND DATA EXTRACTION

English-language articles were selected and data were extracted with a focus on clinical studies of HSC mobilization in patients with NHL or multiple myeloma.

DATA SYNTHESIS

Plerixafor exerts its effect by reversibly blocking the ability of HSC to bind to the bone marrow matrix. When used with granulocyte colony-stimulating factor (G-CSF), plerixafor helps increase the number of HSCs in the peripheral blood, where they can be collected for use in autologous transplantation. In clinical studies, plerixafor was rapidly absorbed after subcutaneous injection, reaching a maximum plasma concentration at approximately 0.5 hours. Plerixafor is renally excreted as the parent drug, with an elimination half-life ranging from 3 to 5 hours. Plerixafor increases circulating CD34+ cells in the peripheral blood, with a peak effect about 6-9 hours after subcutaneous administration. An approximate 2- to 3-fold increase in the CD34+ cell count is seen by the first dose of plerixafor after 4 consecutive days of G-CSF treatment. In 2 Phase 3 studies in patients with NHL or multiple myeloma, addition of plerixafor to G-CSF resulted in a higher CD34+ cell collection with fewer apheresis days, but failed to show better graft durability or overall patient survival for up to 12 months of follow-up.

CONCLUSIONS

Clinical trials have demonstrated that the addition of plerixafor to G-CSF was beneficial for HSC mobilization to peripheral blood for collection and subsequent transplantation in patients with NHL or multiple myeloma. Further studies should assess the benefit of the additive use of plerixafor on clinical outcomes.

Successful stem cell remobilization using plerixafor (mozobil) plus granulocyte colony-stimulating factor in patients with non-hodgkin lymphoma: results from the plerixafor NHL phase 3 study rescue protocol

In a phase 3 multicenter, randomized, double-blinded, placebo-controlled study of 298 patients with non-Hodgkin lymphoma (NHL), granulocyte colony-stimulating factor (G-CSF) plus plerixafor increased the proportion of patients who mobilized >or=5 x 10(6) CD34(+) hematopoietic stem cells (HSCs)/kg compared with placebo plus G-CSF (P < .001). Patients in either study arm who failed mobilization (< 0.8 x 10(6) CD34(+) cells/kg in 2 collections or <2 x 10(6) CD34(+) cells/kg in 4 collections) were eligible to enter the opened-label rescue protocol. Following a 7-day minimum rest period, these patients received G-CSF (10 microg/kg/day) for 4 days, followed by daily plerixafor (0.24 mg/kg) plus G-CSF and apheresis for up to 4 days. Of the 68 patients failing initial mobilization (plerixafor, n = 11; placebo, n = 57), 62 patients (91%) entered the rescue procedure (plerixafor, n = 10; placebo, n = 52). Four of 10 patients (40%) from the plerixafor group and 33 of 52 (63%) from the placebo group mobilized sufficient CD34(+) cells (>or= 2 x 10(6) cells/kg) for transplantation from the rescue mobilization alone (P = .11). Engraftment of neutrophils (11 days) and platelets (20 days) was similar to that in patients who did not fail initial mobilization, and all patients had durable grafts at the 12-month follow-up. Common plerixafor-related adverse events (AEs) included mild gastrointestinal (GI) effects and injection site reactions. There were no drug-related serious AEs. These data support that plerixafor plus G-CSF can safely and effectively remobilize patients with NHL who have failed previous mobilization.

Efficacious but insidious: a retrospective analysis of fludarabine-induced myelotoxicity using long-term culture-initiating cells in 100 follicular lymphoma patients

OBJECTIVE

Fludarabine has been recognized as effective treatment in patients with follicular lymphoma (FL), but can induce myelotoxicity of unknown mechanism.

MATERIALS AND METHODS

Myelotoxicity was assessed by cultivation of two types of hematopoietic progenitor cells: colony-forming units granulocyte-macrophage (CFU-GM) and long-term culture-initiating cells (LTC-IC). Pretreatment amounts of CFU-GM and LTC-IC were correlated to age, gender, stage of disease, bone marrow involvement, and previous therapy. Posttreatment comparison of CFU-GM and LTC-IC was performed after different regimens of chemotherapy: fludarabine-based (FND +/- R), procarbazine-based (COPP +/- R), and CHOP(cyclophosphamide, doxorubicin, vincristine, prednisone) +/- R(Rituximab).

RESULTS

One-hundred patients (median age 55 years; 21 patients relapsed) treated for FL were analyzed. The total number of progenitor hematopoietic cells in both types of cultures varied in wide ranges; for LTC-IC between 0 and 874 cells/mL with a median of 77.71 cells/mL and for CFU-GM between 0 and 531 x 10(2) cells/mL with a median of 30.58 x 10(2) cells/mL. Bone marrow involvement, gender, stage of disease, or previous therapy had no influence on LTC-IC and CFU-GM counts. We identified an increase in LTC-IC, but not CFU-GM, associated with age (p = 0.01). Median figures for CFU-GM and LTC-IC were found to be significantly lower after FND +/- R and COPP +/- R than after CHOP +/- R therapy, compared to baseline values (p < 0.01).

CONCLUSIONS

Fludarabine and procarbazine have a dramatic influence, especially on the most immature hematopoietic cells, mirrored in reduced numbers of LTC-IC. This finding is consistent with clinical observations (poor mobilization after fludarabine) and offers an insight into the mechanism of fludarabine-induced myelotoxicity.