Poor Mobilizer Patients Research Articles

A German-Wide Systematic Study on Mobilization and Collection of Hematopoietic Stem Cells in Poor Mobilizer Patients with Multiple Myeloma prior to Autologous Stem Cell Transplantation

Introduction: In patients with a clinical indication for autologous hematopoietic stem cell transplantation (ASCT), sufficient mobilization of CD34+ precursor cells into peripheral blood is essential to ensure adequate hematopoietic stem cell (HSC) collection prior to intensive therapy. However, with standard granulocyte-colony stimulating factor (G-CSF)-based mobilization schemes, an important minority of patients fail to mobilize sufficient (e.g., >10/µL) CD34+ cell counts into the peripheral blood and are considered as poor mobilizers (PM). Because failure to achieve sufficient CD34+ cell mobilization can negatively affect important clinical treatment endpoints, the use of plerixafor (PLX) was approved to increase CD34+ mobilization in PM patients. Methods: The German non-interventional, multicenter, open-label, prospective OPTIMOB study evaluated HSC mobilization strategies prior to planned ASCT in adult patients with hematologic malignancies (lymphomas or multiple myeloma [MM]) focusing on PM patients. PM patients were defined as follows: (1) never achieving ≥20 CD34+ cells/µL before 1st apheresis, (2) receiving PLX at any timepoint of mobilization, (3) their initially planned stem cell yield had to be reduced, or (4) they had not received apheresis due to low CD34+ count in peripheral blood. Results: 168 of 475 MM patients (35%) participating in the OPTIMOB study were classified as PM, and 155 of them (92%) received PLX (PM+PLX) during the study. PM patients were 40–78 years old, slightly more often male (n = 97, 58%), mostly newly diagnosed (n = 146, 87%) and received highly individualized previous treatments. Ninety-four of the PMs underwent chemotherapy mobilization (65%), and 51 patients (35%) received steady-state mobilization with G-CSF only during 1st mobilization attempt. 92% of the total PM population (n = 155) underwent apheresis, 78% of them (n = 117) achieved >2.0 × 106 CD34+ cells/kg body weight on the 1st day of apheresis. PM+PLX had a higher median total collection result than those PM patients without PLX support (7.2 vs. 5.7 × 106 CD34+ cells/kg body weight). In total, ASCT was performed in 136 PM+PLX (88%) versus 8 PM−PLX patients (62%). Conclusion: The OPTIMOB study showed that a considerable proportion of adult MM patients in Germany are PMs. Even though most of PMs were supported with PLX in the OPTIMOB study, PM-PLX also successfully mobilized HSCs, allowing ASCT in majority of all PMs. However, further analyses are required for treatment optimization in PMs.

Day -1 CD34+ Cells and Platelet Count Predict the Number of Apheresis in Poor-Mobilizer Patients Rescued by Plerixafor.

Plerixafor is widely used as up-front treatment with G-CSF to enhance peripheral blood hematopoietic stem cell output in patients failing previous mobilizations. Less frequently, plerixafor is used to rescue an unsatisfactory mobilization following chemotherapy (CT) and G-CSF. This study investigates if pre-collection factors affect the CD34+ cell harvest in chemotherapy and G-CSF mobilizations rescued by plerixafor. Clinical and hematological data relative to patients, mobilization, and apheresis products were retrospectively examined. The outcome was completing a target cell dose ≥ 2 × 106 CD34+ cells/kg at first apheresis. The effect exerted on the outcome by patient- and disease-related factors was investigated by univariate and multivariate logistic regression analysis. The analysis included data from 42 patients affected by hematological (39 patients) and non-hematological malignancies (three patients). Twenty-nine patients (69%) attained the target cell dose at first apheresis. Twelve out of the remaining 13 patients received an additional plerixafor administration, and all accomplished the transplant dose at a second apheresis procedure. Day -1 CD34+ PB count (OR1.46, 95% CI 1.1-1.9, p = 0.008) and platelet count (OR1.0, 95% CI 1.0-1.0, p = 0.033) predicted the achievement of the target dose at first apheresis, independently of pre-mobilization CT, radiation therapy, and disease status at mobilization. At ROC curve analysis, the best cut-off value predicting the successful collection at first apheresis was 7.5/µL for Day -1 CD34+ cell count (AUC 0.830, 0.69 sensitivity, and 0.92 specificity) and 75 × 109/L for Day -1 platelet count (AUC = 0.736, 0.65 sensitivity and 0.85 specificity). In conclusion, on-demand plerixafor rescue allows a successful stem cell collection, irrespectively of disease type and status, prior CT lines, and radiation exposure. Pre-apheresis CD34+ cells and platelet count predict the need for one or two aphereses.

Successful "on-demand" plerixafor for autologous peripheral blood stem-cells transplantation for relapsed/refractory germ cell tumors.

BackgroundGerm cell tumors represent, among solid cancers, a potentially curable disease even if up to 20% to 30% of patients (pts) relapse after first‐line treatment especially considering intermediate and poor prognosis groups. In this scenario, patients are candidates for high‐dose chemotherapy and autologous stem‐cells transplantation as second‐line treatment even though stem‐cells mobilization potential can be affected by several cycles and regimens of chemotherapy. To date, plerixafor is authorized in poor mobilizer adult pts diagnosed with lymphoma or multiple myeloma and in pediatric solid tumors or lymphoma. Therefore, the use of plerixafor in adult pts with relapsing/refractory GCT is still off label.Materials and methodsIn our study, we describe mobilization and collection of peripheral blood stem cells for 10 pts with germ cell tumors. Six patients underwent plerixafor administration since classified as poor mobilizers based on WBC count (>5.000/μL) and CD34+ cell count (<15/μL) the day before apheresis procedure.ResultsOn the first day of apheresis, plerixafor administration in poor mobilizers made possible a remarkable boost of CD34+ cells in such a way to overlap that of good mobilizers' (32/μL vs 35/μL, respectively, P > .05).ConclusionTherefore, in our experience, plerixafor made a good fraction of poor mobilizer patients eligible for mobilization and collection and able to undergo the predicted autologous stem‐cells transplantation; thus, the lack of access to the use of plerixafor in this setting of patients risks jeopardizing an effective treatment, especially in case of poor prognosis.

Combined G-CSF and Plerixafor enhance hematopoietic recovery of CD34+ cells from poor mobilizer patients in NSG mice

Transplantable CD34+ hematopoietic stem/progenitor cells (HSPCs) are currently isolated mainly from peripheral blood after mobilization with granulocyte colony-stimulating factor (G-CSF). These mobilized CD34+ cells have the potential to generate all blood cell types. For autologous transplantation, the minimal number of mobilized CD34+ cells is 2 × 106 CD34+ cells/kg body weight. However, up to 30% of patients fail to mobilize enough peripheral CD34+ cells after G-CSF treatment. To overcome this limitation, a combination of G-CSF and Plerixafor, a CXCR4 chemokine receptor inhibitor, is proposed to enhance CD34+ cell mobilization in poor mobilizer patients. However, only limited data are available on quantification of the functional quality of such patients' mobilized hematopoietic stem cells. Here, for six poor mobilizer patients, a head-to-head comparison of their CD34+ cells mobilized without versus with Plerixafor was performed to assess their properties with respect to the reconstitution of human hematopoiesis in vivo in immune-deficient mice. Our results indicate that mobilized CD34+ cells recovered after the G-CSF + Plerixafor mobilization protocol have an enhanced intrinsic hematopoietic reconstitution potential compared with CD34+ cells mobilized with G-CSF alone.

Agreements and uncertainties in autologous haematopoietic stem cell mobilization and collection. A Spanish consensus document

Although many experts position statements on autologous stem cell mobilization have been published, there are some aspects that are still under discussion. A Spanish Hematologist expert group was summoned to settle on agreements and uncertainties on PBSCs mobilization, including factors not always considered; as apheresis and cytometry key factors that determine a successful PBSC collection. This document reviews critical factors that define poor mobilizer patients and the tools to better collect the desired stem cells for a successful autologous haematopoietic stem cell transplant.

Outcome Comparison of Lymphoma and Myeloma Patients after Autologous Stem Cell Transplantation (ASCT) with Peripheral Blood Stem Cell Mobilization Between Plerixafor (P) Mobilized in Poor Mobilizer Patients and Non-Plerixafor Mobilized Patients

Background: P is used in combination with G-CSF to improve the mobilization of peripheral blood hematopoietic stem cells in poor mobilizers. Limited data are available in regard to effects of P on post-transplant outcomes in comparison with non-P chemomobilized patients.Methods: In this retrospective study, we compare the engraftment and the outcomes of 34 patients mobilized with P + G-CSF or just-in-time rescue P in combination with chemotherapy and G-CSF to 143 patients (control group) mobilized with G-CSF with or without chemotherapy in lymphoma and myeloma patients who underwent ASCT between February 2012 and April 2014 at the University of Maryland Greenebaum Cancer Center. Post-transplantation outcomes including infections, hematologic recovery, relapse, progression and survival were recorded.Results: The median number of collected of CD34+ cells/Kg was 5.9 x 10(6) in the P group and 12.3 x 10(6) in the control group (p=0.0002). Median time to neutrophil engraftment (>0.5 × 10(9) /L) was comparable between the 2 groups: 12 days for the P group and 11 for the control group (p=0.28). There was a trend toward a shorter time to platelet engraftment (>20 × 10(9) /L) in the control (12 days) compared to the P group (14 days) (p=0.056). Progression-free survival at 1 year after (ASCT) was 88.2% in the P group and 81.8% in the control group. There was no difference in the overall survival of both groups (p=0.62)Conclusions: Short and long-term engraftment and outcomes after ASCT seem to be comparable in lymphoma and myeloma patients receiving plerixafor compared to chemomobilized patients without plerixafor. This observation support the use of plerixafor + G-CSF or just-in-time rescue P in patients who mobilize poorly without P. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Peptides targeting chemokine receptor CXCR4: structural behavior and biological binding studies

CXCR4 is a G-protein-coupled receptor involved in a number of physiological processes in the hematopoietic and immune systems. CXCL12/CXCR4 axis plays a central role in diseases, such as HIV, cancer, WHIM syndrome, rheumatoid arthritis, pulmonary fibrosis, and lupus and, hence, indicated as putative therapeutic target. Although multiple CXCR4 antagonists have been developed, there is only one marketed drug, plerixafor, indicated for stem cell mobilization in poor mobilizer patients. In this work, we have designed and synthesized two peptides, six and seven residues long, using as template the N-terminal region of CXCL12; analyzed their conformations by CD, NMR, and molecular dynamics simulations; simulated their complexes with CXCR4 by docking methods; and validated these data by in vitro studies. The results showed that the two peptides are rather flexible in aqueous solution lacking ordered secondary structure elements and present a promising affinity for CXCR4. This affinity is not revealed for CXCR7, indicating a specificity for CXCR4.

Mobilization Scheme With Cytarabine In Poor Mobilizers Patients Diagnosed With Lymphoma

IntroductionMobilization regimens for hematopoietic stem cell transplantation have not undergone major changes except for the introduction of new drugs such as plerixafor. However, in patients receiving multiple lines of treatment, to obtain a suitable amount of hematopoietic progenitors (PH) is often difficult even with the addition of new drugs. We present our experience with a protocol of mobilization for poor mobilizer patients based on the use of cytarabine. Material and MethodsFrom a total of 111 patients diagnosed with lymphoma who underwent autologous hematopoietic progenitors in our center from January 2005 to March 2013, 32 patients (35% of total) with previous mobilization failure, received cytarabine 400 mg/m2 /day x3 days + G-CSF (filgrastim or lenograstim) 10-16 mg /kg/day from day 7 to the end of collection. Cell blood cound and CD34 assays in peripheral blood were performed from day +11 postchemotherapy, and apheresis was started when CD34 > 10 x10e6/L. Results30 patients had non-Hodgkin lymphoma (NHL) (13 diffuse large B-cell lymphoma, 7 mantle cell lymphoma, 5 follicular lymphoma, 2 MALT lymphoma, 1 angioimmunoblastic lymphoma, 2 cutaneous lymphomas) and 2 Hodgkin's lymphoma (HL). Median age was 49 years (range 27-67). Median number of treatment lines prior to mobilization was 3 (1-5). In all 30 patients with NHL, an adequate amount of CD34 + cells was obtained. Only one patient with HL, who had previously received 5 lines of chemotherapy, did not mobilize. The average time from the end of chemotherapy to start of apheresis was 13.7 days (12-20). The average number of CD34 + cells circulating the starting day of apheresis was 41/μL (11-109). The mean of apheresis performed was 1.8 (1-3) with an average amount of CD34 obtained of 4.69 x10e6/kg (1.5-6.8). All patients received outpatient treatment and only 2 required hospitalization: one for short-term neutropenic fever and another due to a limited cutaneous hemorrhage during the neutropenia phase. All patients were transplanted without incidence and successfully engrafted. None required G-CSF early postransplant. ConclusionsMobilization with intermediate-dose cytarabine has proven to be a cost-effective regimen in lymphoma patients with prior mobilization failure. Disclosures:No relevant conflicts of interest to declare.

Use of Plerixafor in Predicted and Proven Poor Mobilizer (according to GITMO criteria). Experience of Policlinico Universitario Tor Vergata

AbstractAbstract 4415 BACKGROUND.Autologous stem cell transplantation (ASCT) of PBSCs has become a widely applied treatment for Multiple Mieloma (MM), non- Hodgking’s lymphoma (NHL) and Hodgking’s lymphoma (HL). Successful engraftment correlates with the number of CD34 hemopoietic progenitors cells infused. However, a part of MM or lymphoma patients (5% to 40%) fail to mobilize adequate numbers of PBSCs and thus cannot undergo to ASCT. The success of PBSCs mobilization is usually assessed by the total number of CD34+ stem cells collected, with a cutoff of 2.0–2.5 ×106 CD34+ cells/kg recipient body weight being considered as a minimum requirement for transplant. Poor mobilization of PBSCs is a major limitation to ASCT. Recently GITMO Working Group worked to define operational criteria for the identification/prediction of the poor mobilizer (PM) patients (Olivieri et al. 2011). Plerixafor, a CXCR4 chemochine antagonist, has been showed to improve significantly PBSC mobilization in PM patients. We present our experience using Plerixafor in PM patients classified according to GITMO criteria. METHODS.Between September 2009 and June 2012, a total of 17 patients (9F-8M) were enrolled. The diagnosis were: 10 MM (5F-5M), 1HL (1M), 6 NHL (4F-2M). The median age was 57 (range 15–66). 7 patients (3MM, 4NHL) were defined “Proven PM” and 10 patients (7MM, 2NHL, 1HL) “Predicted PM” according to GITMO criteria. The mobilization protocol included G-CSF, administered at a dose of 10μg/kg daily on 4 consecutive days. In the evening of the fourth day, patients received subcutaneous plerixafor at a dose of 0,24 mg/kg. Apheresis was initiated on the fifth day, 10–12 h after plerixafor and 1 h after G-CSF administration. Apheresis and daily administration of G-CSF and plerixafor continued until the patient collected enough CD34+ cells for auto- HSCT (> 2 ×106/kg; max 7 plerixafor injections if required). PBSC collection was initiated if peripheral CD34+ cells count was >10μl. A successful mobilization was defined as a total yeld of > 2×106/kg. RESULTS.13 patients (76,5%) collected the minimum number of CD34 cells > 2×106/kg. The diagnosis were: 8MM, 1HL,1 NHL. 7 patients (2NHL; 4 MM; 1 LH; 7 predicted) were able to collect > 5×106/Kg. Only 4 patients (3 MM; 1 LNH; 4 proven) failed the mobilization because the numbers of cells CD34 were < 10μL and these patients did not undergo to apheresis procedures. The collection target of 2×106/Kg was reached in a median of 2 apheresis session (range 1–3). The technical characteristics of the procedures were (median value): blood volume processed 12 L (range 9–14), total CD34+/Kg collected 3,06 × 106(range 2,21-8,62), procedure efficiency 47,5% (range 35,3–79), duration of the procedure 261 minutes (range 210–309). Plerixafor was well tolerated and mild side effects were: reactions in the injection site, gastrointestinal disturbs, muscle pain. During administration of plerixafor we did not observe any significant laboratory abnormalities of liver or renal function. CONCLUSION.Unsuccessful mobilization represents an important limitation to ASCT in lymphoma and MM. In our experience plerixafor allowed to collect an appropriate amount of CD34 also in patients defined “proven PM” significantly reducing the percentage of patients that could not undergo ASCT (target value obtained in 43% of “proven PM”). Confirming the recent literature plerixafor is well tolerated with minimal side effects. We retrospectively applied GITMO criteria for PM patients and our experience, although limited, confirm that the use of a correct definition of PM allows the appropriate use of new mobilizing agents like plerixafor increasing significantly the therapeutic options also in patients who had no possibilities to receive an ASCT with the traditional mobilizing therapy. Disclosures:No relevant conflicts of interest to declare.

A prospective study on the efficacy of mobilization of autologous peripheral stem cells in pediatric oncohematology patients

Peripheral blood stem cells (PBSCs) are the preferred source in autologous transplantation. We assessed prospectively the efficacy of mobilization in pediatric patients and risk factors associated with its failure. Patients, aged 0 to 17 years, needing a first collection of PBSCs for autologous stem cell transplantation were eligible. The study period was from July 2008 to September 2010. A blood peak of fewer than 20 × 10(6) CD34+ cells/L was used as the cutoff to define a poor mobilizer. A total of 145 patients, 57% male (82) and 43% female (63), with a median age of 7 years, affected by solid tumor, 79% (114), and acute leukemia or lymphoma, 21% (31), were enrolled. Granulocyte-colony-stimulating factor used was filgrastim in 69%, lenograstim in 26%, and pegfilgrastim in 5% of patients. A total of 83% (121) of patients mobilized successfully, the median CD34+ count being 120 × 10(6) /L (range, 23 × 10(6) -1840 × 10(6) /L). A single leukapheresis procedure was sufficient to achieve the target CD34+ cell dose in 82% (99/121) of patients. Among 24 poor mobilizer patients, 15 underwent a second mobilizing course and nine required a marrow harvest. Factors associated with poor mobilization were metastatic disease and relapse. Among 99 patients who underwent autologous stem cell transplantation, the median times to neutrophil and platelet engraftment and of hospitalization were longer by 2, 12, and 6 days in poor versus good mobilizer group. In pediatric patients undergoing a first mobilization, the incidence of poor mobilization was 17%. Failure of mobilization resulted in an increase in health costs and a longer hospitalization for those who underwent autologous stem cell transplantation.

Poor mobilization status: a lingering legacy for allograft recipients

Poor mobilization of autologous peripheral blood stem cells (HPC-A) in patients requiring high dose chemotherapy represents an ongoing clinical challenge. A key diffi culty in interpreting the literature in this area is that there is no uniform defi nition of poor mobilization. A mobilization “ failure ” at one institution may represent “ suboptimal mobilization ” at another, and thresholds for defi ning a peripheral blood CD34 count as suffi cient to commence collection vary dramatically between institutions. Th e most common reason for a failure to mobilize and collect HPC-A is prior exposure to cytotoxic chemotherapy, in particular protracted courses of alkylators and purine analogs [1 – 3]. More recently lenalidomide exposure has also been implicated in impairment of HPC-A [4]. A recognition and avoidance of these risk factors and the well-timed use of novel mobilization therapies such as plerixafor have seen a lower incidence and greater ability to salvage those patients demonstrating HPC-A mobilization [5,6]. Where repeated attempts at salvage mobilization have been required to obtain a transplantable dose of cells, there are concerns that this subset of hard-to-mobilize patients have an adverse disease-free and overall survival following autologous transplant [7]. Th e mechanism of the suboptimal outcome in patients with a history of poor HPC-A is likely to be complex. Th is group of patients is enriched for patients with refractory disease, who are likely to have residual tumor involvement within the marrow resulting in cell contamination of the graft (the signifi cance of which remains uncertain [8]), and bone marrow microenvironmental damage as a result of multiple lines of prior therapy and multiple mobilization attempts. As a result of these factors and despite the application of granulocyte-colony stimulating factor (G-CSF) and/or plerixafor there is a small group of patients who ultimately cannot achieve an adequate collection for safe autologous transplant. In this edition of Leukemia and Lymphoma , Crocchiolo and co-authors explore whether a history of poor mobilization continues to impart a similar adverse outcome in a cohort of patients with multiple myeloma or lymphoma despite receiving a normal stem cell donation from an allogeneic donor following reduced intensity conditioning [9]. In a retrospective analysis they identifi ed two cohorts of patients who had previously attempted autologous stem cell mobilization but for various reasons proceeded to allogeneic transplant. Compared to the cohort of prior “ good mobilizers, ” defi ned as a CD34 cell count 20 10 9 /L on the fi rst day of apheresis, the group of “ poor mobilizers, ” who failed to achieve this threshold, had an increased non-relapse mortality. Th is diff erence was not due to impaired myeloid engraftment, as post-allogeneic transplant recovery of neutrophils and platelets was similar in the two cohorts. Somewhat paradoxically, assessment of a sub-cohort who, despite being defi ned as poor mobilizers, ultimately succeeded in the collection of 2 10 6 /kg CD34 cells, showed a slower neutrophil engraftment. Th is fi nding may refl ect a group enriched for patients in whom the disease risk resulted in an imperative to move to transplant, which in turn led to more collection days and/or more repeated mobilization attempts, and who were likely to be more heavily pretreated, with a resultant impairment of the bone marrow microenvironment and delayed allogeneic stem cell engraftment. Overall the poor mobilizer cohort had similar rates of relapse and graft-versus-host disease to those of the good mobilizers. Despite this, the non-relapse mortality and overall survival were signifi cantly worse in the poor mobilizer group. Th is fi nding was independent of the patient/donor gender matching or number of prior autografts. No clear pattern emerged in the cause of death in these patients. In the allograft setting, where the engrafting cells are presumably healthy, the putative “ lesion ” in graft dysfunction is likely to be the marrow microenvironment. Whilst platelet and neutrophil engraftment were not clearly impaired in this study, immune reconstitution was not measured. Recovery of lymphocyte subsets, and perhaps just as importantly lymphocyte function, may lag substantially in poor mobilizer patients. Where it has been studied, posttransplant lymphocyte recovery is directly correlated with post-transplant outcome in the autograft and allograft setting [10 – 12]. Impaired lymphocyte recovery in the poor mobilizer group could translate to increased susceptibility

A specific time course for mobilization of peripheral blood CD34+ cells after plerixafor injection in very poor mobilizer patients: impact on the timing of the apheresis procedure

This report describes the specific kinetics of the peripheral blood (PB) CD34+ cell concentration in a selected group of very poor stem cell mobilizer patients treated with granulocyte-colony-stimulating factor (G-CSF) and plerixafor and determines the kinetics' impact on apheresis. All patients had previously experienced at least two failures of mobilization (without use of plerixafor). The present salvage therapy consisted in the administration of 10 µg/kg/day G-CSF for 5 days added to a dose of plerixafor administered at between 5 a.m. and 6 a.m. on Day 5. The PB CD34+ cell counts were tested every 3 hours thereafter. Apheresis was initiated as soon as the PB CD34+ cell count reached 10 × 10(6) /L. A PB CD34+ cell count higher than 10 × 10(6) /L was observed as soon as 3 hours after plerixafor administration in 10 of the 11 patients who reached this threshold at some point in the monitoring process. Interestingly, all patients presented an early decrease in the PB CD34+ cell count 8 to 12 hours after plerixafor administration (below 10 × 10(6) /L for seven patients). Had such patients been tested for PB CD34+ cell mobilization according to conventional criteria (i.e., 11 hr after plerixafor administration), apheresis would not have been performed at the optimal timing. For very poor stem cell mobilizer patients, early monitoring of PB CD34+ cell count may be required for the optimal initiation of apheresis.

Plerixafor Added to Chemotherapy Plus G-CSF Is Safe and Allows Adequate PBSC Collection in Predicted Poor Mobilizer Patients with Multiple Myeloma or Lymphoma

We evaluated the safety and efficacy of plerixafor, subsequent to disease-specific chemotherapy followed by granulocyte-colony stimulating factor (G-CSF), in 37 multiple myeloma (MM) or lymphoma patients, who were candidates for autologous stem cell transplantation (ASCT) predicted as poor mobilizers (PMs). Patients were identified as predicted PMs according to the history of a previously failed mobilization attempt or the presence of ≥1 factors predicting an unsuccessful harvest, such as advanced disease, prior extensive radiotherapy, or prolonged treatment, with stem cell poisons, advanced age, or extensive bone marrow involvement. Plerixafor (0.24 mg/kg) was administered subcutaneously for up to 3 consecutive days while continuing G-CSF for 9 to 11 hours before the planned apheresis. Plerixafor administration was safe and no significant adverse events were recorded. We observed a median 4-fold increase (range: 1.4-32) in the number of circulating CD34(+) cells following plerixafor compared with baseline CD34(+) cell concentration (from a median of 5 cells/μL, range: 1-32, to a median of 32 cells/μL, range: 6-201). Twenty-seven of the 37 patients (14 of 17 with MM and 13 of 20 with lymphoma) had ≥2×10(6) CD34(+) cells/kg collected in 1-3 apheretic procedures. Of the 27 patients rescued with plerixafor, 24 (13 MM, 11 lymphoma) have been transplanted with plerixafor-mobilized peripheral blood stem cells, showing a rapid and durable hematologic recovery. Our results suggest that the addition of plerixafor to G-CSF after disease-oriented chemotherapy is safe and allows for a satisfactory harvest in order to perform a safe ASCT, in a relevant proportion of lymphoma and MM patients considered to be PMs.

Plerixafor Plus Single-Dose Pegfilgrastim for Hematopoietic Stem and Progenitor Cell Mobilization: An Efficient and Safe Regimen In Good and Poor Mobilizer Patients

AbstractAbstract 2256Plerixafor (Mozobil®) is indicated in combination with daily filgrastim for hematopoietic stem and progenitor cell (HSPC) mobilization and subsequent autologous transplantation in patients with non-Hodgkin Lymphoma and multiple myeloma. In off-label use, pegfilgrastim (Neulasta®) is known to mobilize HSPC with a single injection. We hypothesise that pegfilgrastim is an attractive adjunct to plerixafor as a combination mobilizing regimen in both good- and poor-HSPC mobilizer patients, much like filgrastim but with the advantage to the patient of fewer injections. To-date there have been no published trials examining this combination. Aim:To investigate the tolerability, kinetics and efficacy of plerixafor plus pegfilgrastim for HSPC mobilization in patients with lymphoma or myeloma. Method:Twelve patients with lymphoma (n=10) and myeloma (n=2) underwent HSPC mobilization using single-dose pegfilgrastim (6mg SC mane D1) and nightly plerixafor (0.24 mg/kg SC nightly commencing 2200–2300hrs D3). Peripheral blood (PB) CD34+ monitoring commenced D3 and continued until the completion of apheresis. Apheresis commenced in all patients on D4. Nightly plerixafor/daily apheresis continued for up four doses/procedures, or until the target CD34+ yield (5×106/kg) was reached. CD34+ yields and kinetics were compared with historical controls mobilized with pegfilgrastim alone. Historical controls were mobilized with a single pegfilgrastim injection (6mg or 12mg SC mane D1), and PB CD34+ monitoring commenced on D4. Patients:Six ‘predicted poor-mobilizers’ (5 prior failed, 1 fludarabine-exposed) and 6 ‘predicted adequate-mobilizers’ were mobilized with pegfilgrastim plus plerixafor. Historical controls (n=22; 4 poor mobilizers) were mobilized with pegfilgrastim alone. Results:Four of 12(33%) study patients had a PB CD34+ count ≥5×106/L (our institutional threshold for collection) on D3 post-pegfilgrastim, however apheresis was commenced on D4 in all patients; all study patients surpassed this threshold by D4 (i.e. post-D3 evening dose of plerixafor). PB CD34+ counts peaked on D4 in 6/12 study patients and were sustained ≥5×106/L for 4 and 5 days in 8/12(67%) and 4/12(33%), respectively. Compared to historical controls, study patients were more heavily pre-treated (median prior regimens 2(1-4) vs. 1(0-2); P=0.002), and contained a higher proportion of poor mobilizers (50% vs. 18%; P=0.06). All study patients and 20/22 controls collected ≥2×106/kg CD34+ cells within 4 aphereses (P=0.53). Eleven of 12(92%) study patients vs. 16/22(76%) controls achieved this target after 2 apheresis procedures (P=0.37). After a maximum of 4 aphereses, there was a trend to higher median total CD34+ yields in the plerixafor plus pegfilgrastim patients compared to pegfilgrastim-alone patients; 8.0 ×106/kg (2.4-12.9 ×106/kg) vs. 4.8 (0.4-14.0 ×106/kg) (P=0.07), within a median of 1(1-4) vs. 2(1-4) collections (P=0.57). Study patients were assessed for the presence of tumor cells in the PB or apheresis product. One study patient with minimal BM involvement by lymphoplasmacytic lymphoma at baseline developed minimal detectable plasma cells in the PB and the apheresis product on D4 (post-plerixafor). One historical control patient with POEMS syndrome developed hyperleukocytosis after 12mg pegfilgrastim, which resolved without incident. The plerixafor plus pegfilgrastim combination was well tolerated: bone pain (worst grade=3, n=2), gastrointestinal symptoms (diarrhoea: worst grade=2, n=2) and facial paraesthesiae (n=3) were the most frequent adverse events. Engraftment data is currently being collected. Conclusion:Plerixafor plus pegfilgrastim is a simple, safe and effective HSPC mobilization regimen in myeloma and lymphoma, in both poor and good mobilizers. Comparison with historical controls suggests that the addition of plerixafor to pegfilgrastim may overcome risk factors for failed mobilization such as prior mobilization failure and heavy prior chemotherapy exposure, enabling even predicted poor mobilizer patients to achieve target CD34+ yields, often within just two apheresis procedures. Disclosures:Herbert: Genzyme: Research Funding, Speakers Bureau; Amgen: Speakers Bureau. Off Label Use: Pegfilgrastim was used for hematopoietic stem and progenitor cell mobilization, which is an off-label indication. The use of pegfilgrastim for this purpose is widely published. Prince: Amgen: Consultancy, Honoraria, Research Funding.

AML Patients In First CR with Intermediate Risk Cytogenetic and High Level of CD34+ Mobilization Have Better DFS After Allogeneic Transplantation.

AbstractAbstract 4563AML patients having a high apheretic yield in CD34+ cells during mobilization have a poor prognosis, independently from cytogenetic risk (Feller 2004, Keating 2004). It is however not known if prognostic value of PBSC mobilization is retained after different post remissional treatment and clinical usefullness of this prognostic information in dealing with intermediate cytogenetic group patients, the more represented AML subgroup in which post remissional therapy is still a controversial issue. METHODSA group of 64 AML adult patients in 1st CR was prospectively studied. PBSC mobilization was attempted following first consolidation course. Cytogenetic assessment at diagnosis was available in 95% of patients. Post remissional treatment was chosen based on cytogenetic risk, sibling donor availability and presence of others prognostic factors, MUD transplants were proposed in cytogenetic high risk patients or in selected young patients with intermediate cytogenetic, Autologous HSC Transplantation was proposed when allogeneic transplant was felt not indicated, no further therapy was administered in patients deemed ineligible for any kind of transplantation. Prognostic significance of CD34+ cells was evaluated measuring DFS in groups of patients identified from value of CD34+ peak in respect to 50th percentile (CD34 peak: 65×10e6/L) and 75th percentile (197×10e6/L). Those patients having a CD34+ cell peak below median value (65×10e6/L) were categorised as LOW MOBILIZER, those having a CD34+ peak between 65 and 197 ×10e6/L were categorised as GOOD MOBILIZER, and those having a CD34+ peak over 75th percentiles (197 ×10e6/L) were categorised as SUPERMOBILIZER. RESULTSIn our serie 40% of patients received an Allogeneic transplant after a myeloablative treatment, 49% an autologous transplant while 11% no further chemotherapy. Disease Free Survival (DFS) was 60%. CD34+ peak during mobilization, evaluated as a continuous variable, in a Cox regression model resulted important for DFS (hazard ratio:1.001; p=0.01). Importance of CD34+ peak was maintained also when the stratum of patients with intermediate cytogenetic risk was analysed (DFS: p=0.002). POOR MOBILIZER, GOOD MOBILIZER and SUPERMOBILIZER patients had statistically different DFS when cases were analysed as a whole (DFS: POOR M.: 70%; GOOD M. 50%; SUPER M: 30%; log rank: p=0.05); mobilizing efficiency was important for DFS also in intermediate cytogenetic group (DFS: POOR M. 70%; GOOD M. 40% DFS; SUPER M. 28%; log rank p= 0.02), importance was maintained also in patients treated by allogeneic transplantation or with autologous transplantation (fig.1).When allogeneic transplantation was compared to the group of patients receiving autologous transplantation or other post remissional strategies both in the cases as a whole and in the stratum of intermediate cytogenetic (table 1), the group of POOR mobilizer had after autologous transplants results non different from patients receiving allogeneic transplantation, however, the group of GOOD mobilizer patients had after allogeneic transplants a DFS significantly better compared to other treatment while SUPER mobilizer patients had poor results also when allogeneic transplantation was employed.In conclusion in AML in 1st CR, evaluation of CD34 peak during mobilization is a parameter providing prognostic informations useful also within intermediate cytogenetic group.INTERMEDIATE CYTOGENETIC RISK (n.42)DFS (All patients) (n.42)DFS (Autologous Tx Group) (n.16) or no Tx (n.6)Log rankDFS (Allogeneic Tx Group) (n.20)CD34+ LOW MOBILIZER70%65%NS80%CD34+ GOOD MOBILIZER40%0%p=0.0275%CD34+ SUPER MOBILIZER28%0%NS30%Log rankp=0.02p=0.005p=0.04 [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Large‐volume‐apheresis facilitates autologous transplantation of hematopoietic progenitors in poor mobilizer patients

Given that pre-apheresis CD34(+) cell count (PA-CD34) predicts the apheresis' yield, a minimum of 5 to 20 PA-CD34/microl is required in many institutions to initiate cell collection. The aim of this study was to clarify whether large-volume-apheresis (LVA) could facilitate progenitor cell transplantation in patients with low PA-CD34. Apheresis was initiated in 226 patients, disregarding PA-CD34, at days: +5 in G-CSF, +10 in cyclophosphamide+G-CSF, and +15 to +20 in other chemotherapy+G-CSF mobilization, when leucocytes >2.5 x 10(9)/L. Four times the blood volume was processed. Patients were grouped according to their PA-CD34: >or=10/microl (group-A, n = 143); <10/microl but >or=5/microl (group-B, n = 40) and <5/microl (group-C, n = 43). No differences were found in diagnoses, gender, age, previous treatments or mobilization regimen between groups. Enough CD34(+) cells (>1.9 x 10(6)/kg) were obtained in 31 patients (72%) from group-C, although in this group two mobilizations were needed in 20 patients (46.5%), compared to 5 (3.5%) and 1 (2.5%) in groups A and B, respectively (P < 0.01). Evenly three apheresis or more were required in 28 patients (65.1%) from group-C, compared to 8 (5.6%) and 6 (15.0%) in groups A and B, respectively (P < 0.01). In conclusion LVA can facilitate autologous transplantation in poor-mobilizer-patients, low PA-CD34 should not be an inflexible exclusion factor.