Plerixafor on-demand combined with chemotherapy and granulocyte colony-stimulating factor: significant improvement in peripheral blood stem cells mobilization and harvest with no increase in costs

Impact of plerixafor use in the mobilization of blood grafts for autologous hematopoietic cell transplantation

Plerixafor (PLER), a reversible antagonist of the CXC chemokine receptor type 4, has been in clinical use for mobilization of blood grafts for autologous hematopoietic cell transplantation (AHCT) for about 15 years. Initially PLER was investigated in placebo-controlled trials with the granulocyte colony-stimulating factor (G-CSF) filgrastim. It has also been used in combination with chemotherapy plus G-CSF in patients who had failed a previous mobilization attempt or appeared to mobilize poorly with current mobilization (preemptive use). This review summarizes what is known regarding addition of PLER to standard mobilization regimens. PLER increases mobilization of CD34+ cells, decreases the number of apheresis sessions needed to achieve collection targets and increases the proportion of patients who can proceed to AHCT. It appears also to increase the amount of various lymphocyte subsets in the grafts collected. In general, hematologic recovery after AHCT has been comparable to patients mobilized without PLER, although slower platelet recovery has been observed in some studies of patients who mobilize poorly. In phase III studies, long-term outcome has been comparable to patients mobilized without PLER. This also appears to be the case in patients receiving plerixafor for poor or suboptimal mobilization of CD34+ cells. In practice, PLER is safe and has not been shown to increase tumor cell mobilization.

Mobilization and Hematopoietic Stem Cell Collection in Poor Mobilizing Patients with Lymphoma: Final Results of the German OPTIMOB Study

Introduction

Successful mobilization and collection of peripheral hematopoietic stem cells (HSCs) are necessary for lymphoma patients eligible for myeloablative chemotherapy with subsequent autologous stem cell transplantation (ASCT). Albeit G-CSF alone or combined with chemotherapy is well-established methods for HSC mobilization, up to 40% of the patients fail to mobilize (poor mobilizer, PM). Plerixafor (PLX) is commonly used in PM patients resulting in increased migration of HSCs into peripheral blood and thus improves the collection outcome.

Methods

The prospective, multicenter, open-label, non-interventional OPTIMOB study assessed mobilization and collection parameter of patients with lymphoma or multiple myeloma to get deep insights in the treatment of those patients in clinical routine focusing on PM patients. PM was defined as follows: (1) no achievement of ≥20 CD34+ progenitor cells/µL before first apheresis, (2) PLX administration at any time point during the observational period, (3) reduction of the initially planned CD34+ progenitor cell yield as necessity due to failed mobilization or HSC collection, and (4) no performance of apheresis due to low CD34+ progenitor level. Primary objective of the study was to assess mobilization success by the proportion of PM patients achieving >2 × 106 CD34+ progenitor cells/kg body weight on the first day of apheresis. Here, the data of the lymphoma cohort are presented.

Results

Out of 238 patients with lymphoma documented in the study, 32% were classified as PM. 87% of them received PLX. Demographic data revealed no obvious differences between PM and good mobilizing (GM) patients. All patients were treated highly individualized prior to mobilization. Majority of all PM patients were able to undergo apheresis (95%) and reached their individual requested CD34+ progenitor cell target (72%). 57% of the PM patients achieved >2.0 × 106 CD34+ progenitor cells/kg body weight on day 1 of apheresis and nearby 70% of them underwent ASCT. Median time to engraftment was similar in PM and GM patients of the lymphoma cohort.

Conclusions

Majority of PM patients with lymphoma were successfully mobilized and underwent ASCT. Most of them received PLX during the study.

Stem cell mobilization in multiple myeloma: challenges, strategies, and current developments

Among hematological malignancies, multiple myeloma (MM) represents the leading indication of autologous hematopoietic stem cell transplantation (auto-HCT). Auto-HCT is predominantly performed with peripheral blood stem cells (PBSCs), and the mobilization and collection of PBSCs are essential steps for auto-HCT. Despite the improved success of conventional methods with the incorporation of novel agents for PBSC mobilization in MM, mobilization failure is still a concern. The current review comprehensively summarizes various mobilization strategies for mobilizing PBSCs in MM patients and the evolution of these strategies over time. Moreover, existing evidence substantiates that the mobilization regimen used may be an important determinant of graft content. However, limited data are available on the effects of graft characteristics in patient outcomes other than hematopoietic engraftment. In this review, we discussed the effect of graft characteristics on clinical outcomes, mobilization failure, factors predictive of poor mobilization, and potential mobilization regimens for such patients.

Outcomes of poor peripheral blood stem cell mobilizers with multiple myeloma at the first mobilization: A multicenter retrospective study in Japan

Autologous stem cell transplantation (ASCT) remains an important therapeutic strategy for multiple myeloma; however, a proportion of patients fail to mobilize a sufficient number of peripheral blood stem cells (PBSCs) to proceed to ASCT. In the present study, we aimed to clarify the characteristics and outcomes of poor mobilizers. Clinical data on poorly mobilized patients who underwent PBSC harvest for almost 10 years were retrospectively collected from 44 institutions in the Japanese Society of Myeloma (JSM). Poor mobilizers were defined as patients with less than 2 × 10⁶/kg of CD34⁺ cells harvested at the first mobilization. The proportion of poor mobilization was 15.1%. A sufficient dataset including overall survival (OS) was evaluable in 258 poor mobilizers. Overall, 92 out of 258 (35.7%) poor mobilizers did not subsequently undergo ASCT, mainly due to an insufficient number of PBSCs. Median OS from apheresis was longer for poor mobilizers who underwent ASCT than for those who did not (86.0 vs. 61.9 mon., p = 0.02). OS from the diagnosis of poor mobilizers who underwent ASCT in our cohort was similar to those who underwent ASCT in the JSM database (3y OS rate, 86.8% vs. 85.9%). In this cohort, one‐third of poor mobilizers who did not undergo ASCT had relatively poor survival. In contrast, the OS improved in poor mobilizers who underwent ASCT. However, the OS of extremely poor mobilizers was short irrespective of ASCT.

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

Background

Germ 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 methods

In 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.

Results

On 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).

Conclusion

Therefore, 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.

Use of Plerixafor for Stem Cell Mobilization in the Setting of Autologous and Allogeneic Stem Cell Transplantations: An Update

Mobilization failure is an important issue in stem cell transplantations. Stem cells are yielded from the peripheral blood via apheresis. Granulocyte colony-stimulating factor (G-CSF) is the most commonly used mobilization agent among patients and donors. G-CSF is administered subcutaneously for multiple days. However, patients with mobilization failure cannot receive autologous stem cell transplantation and, therefore, cannot be treated adequately. The incidence rate of mobilization failure among patients is about 6–23%. Plerixafor is a molecule that inhibits the binding of chemokine receptor-4 with stromal-cell-derived factor-1, thereby resulting in the release of CD34+ cells in the peripheral blood. Currently, plerixafor is used in patients with mobilization failure with G-CSF and is administered subcutaneously. Several studies conducted on different clinical settings have shown that plerixafor is effective and well tolerated by patients. However, more studies should be conducted to explore the optimal approach for plerixafor in patients with mobilization failure. The incidence of mobilization failure among donors is lower. However, plerixafor is not approved among donors with mobilization failure. Moreover, several clinical studies in donors have shown a beneficial effect of plerixafor. In addition, the adverse events of plerixafor are mild and transient, which can overcome the adverse events due to G-CSF. This review assessed the current role and effects of plerixafor in stem cell mobilization for autologous and allogeneic stem cell transplantations.

Optimization of repeat plerixafor dosing for autologous peripheral blood stem-cell collection

INTRODUCTION

Peripheral CD34+ cells may be mobilized using filgrastim alone or in combination with chemotherapy. The addition of plerixafor can be efficacious, though guidelines for repeat dosing are lacking.

MATERIAL AND METHODS

This quality improvement project was initiated to generate guidelines for repeat plerixafor dosing after retrospective evaluation of data in adult patients undergoing autologous peripheral blood stem cell mobilization and collection.

RESULTS

Analysis included 195 patients: 119 (61 %) with multiple myeloma and 76 (39 %) with lymphoma. Patients given at least one dose of plerixafor (n = 109) were further divided: Group 1) (A) goal of 3 × 10E6/kg and day 1 peripheral blood CD34+ count < 30 × 10E6/L, vs (B) ≥ 30 × 10 E6/L; Group 2) (A) goal of 6 × 10E6/kg and day 1 peripheral blood CD34+ count < 50 × 10E6/L or < 50 % of collection goal after day 1, vs (B) ≥ 50 % of collection goal after day 1. Ninety five percent of cases in Group 1B and 88 % of cases in Group 2B did not receive additional plerixafor doses and all of them achieved their collection goals. In contrast, those in Groups 1A and 2A required additional plerixafor dosing and some mobilizations/collections were futile.

CONCLUSION

Based on these data, with consideration of collection goal, peripheral blood CD34+ count, and CD34+ cell bag count on collection day 1, we have generated institutional guidelines for collection initiation and repeat plerixafor dosing. Long term, we predict these guidelines will optimize pharmacy, apheresis, and stem cell processing resources while improving the patient experience.

Threshold for optimal administration of plerixafor in autologous peripheral blood stem cell collections through CD34+ cell monitoring based on the experience from two Japanese university hospitals

Plerixafor was introduced to Japan in 2017 as a stem cell mobilization enhancement reagent, but the threshold for its use remains unclear. In this study, we assessed 57 patients treated with plerixafor (33 patients with multiple myeloma (MM) and 24 with malignant lymphoma (ML) and 152 patients without plerixafor administration. When CD34+ cell pre-counts were between 5.5 and 20 cells/μL in MM or 6 and 21 cells/μL in ML, the CD34+ cell count increased significantly, attaining the highest yield in response to plerixafor (achievement rate by one leukapheresis is 93.3% and 91.7% in MM and ML, at P < .001 and P = .012, respectively). In case the CD34+ cell pre-count was less than 5.5 cells/μL, an increase of at least 7 cells/μL from baseline by plerixafor was the necessary condition to achieve successful collection through a two-time leukapheresis. Monitoring CD34+ cell numbers might improve the collection efficiency and reduce the cost.

Plerixafor on-demand in association with low-dose cyclophosphamide and G-CSF in the mobilization of patients with multiple myeloma: High effectiveness, low toxicity, and affordable cost

•

In CD34 mobilization of Multiple Myeloma patients, Cyclophosphamide at the dose of 4 gr/m2 is usually administered. A lower dose of Cyclophosphamide (1.5–2.0 gr/m2) has a lower mobilizing effect and, for this reason, this dose is not widely used in CD34+ cells mobilization.

•

The use of Plerixafor on demand, however, could have changed these conclusions. We hypothesized that when used in conjunction with on-demand Plerixafor, low lose CTX is more advantageous than the higher dose.

•

The results of this prospective trial support, indeed, the view that low dose Cyclophosphamide in association to on-demand PLX allows the reaching efficacy and low toxicity.

In CD34+ cells mobilization of patients with multiple myeloma (MM), the use of Cyclophosphamide (CTX) at a dose of 2 g/m² has low efficacy although also lower toxicity. The suboptimal mobilizing effect of low-dose CTX, however, may be overcome by plerixafor (PLX) on demand.

We conducted a prospective multicenter study in 138 patients with MM to evaluate CTX 2 g/m² in association with granulocyte-colony stimulating factor (G-CSF) and on-demand PLX. We compared results with a historical group of MM patients (n = 138) mobilized using CTX at a dose of 4 g/m².

CD34+ cells greater than 2 × 10⁶/kg in max three aphereses were harvested in 98.6% of patients in the on-demand PLX study group while in 84.0% in the historical group, (p = 0.0001). In the on-demand-PLX study group, a successful harvest greater than 5 × 10⁶/kg in max three aphereses was observed in 85.5% of patients versus 62.3% of patients in the historical control group, (p=0.0001). In the on-demand-PLX study group, 4.3% (6/138) of patients had febrile complications. Salvage mobilization in the on-demand PLX study group was 1.4%.

In conclusions, on-demand PLX + CTX 2 g/m2 + G-CSF 10 μg/kg has higher efficacy and lower toxicity compared with CTX 4 g/m2 + G-CSF. An analysis of costs is presented.

Factors that predict delayed platelet recovery after autologous stem cell transplantation for lymphoma or myeloma

The amount of infused CD34⁺ cells has been reported to be the strongest predictor of platelet recovery after autologous stem cell transplantation (ASCT). However, the timing of platelet recovery varies widely among patients even after the infusion of similar amounts of CD34⁺ cells. Therefore, we retrospectively assessed 99 patients who underwent their first ASCT for lymphoma or myeloma at our center. Thirteen patients (13%) did not achieve platelet engraftment, defined as a platelet count of at least 2.0 × 10⁴/μL without transfusion, at day 28 after transplantation, whereas 58 of 60 patients (97%) who received at least 2.0 × 10⁶/kg CD34⁺ cells achieved platelet engraftment within 28 days. Multivariate analysis identified the following significant risk factors for delayed platelet recovery: hemoglobin level and platelet count before stem cell harvest, body temperature of > 39 °C within 5 days after ASCT, and infusion of a small amount (< 2.0 × 10⁶/kg) of CD34⁺ cells. In a subgroup analysis of 39 patients infused with < 2.0 × 10⁶/kg CD34⁺ cells, a need for repeated apheresis for stem cell harvest and a body temperature of > 39 °C within 5 days after ASCT were identified as independent factors for delayed platelet recovery. In summary, platelet recovery following ASCT was affected by insufficient hematopoietic recovery at stem cell harvest, a need for repeated apheresis, and high fever early after ASCT, particularly when the amount of infused stem cells was insufficient.

Impact of Plerixafor Use at Different Peripheral Blood CD34+ Thresholds on Autologous Stem Cell Collection in Patients with Multiple Myeloma

Patients with multiple myeloma (MM) scheduled for autologous stem cell transplantation must undergo autologous stem cell mobilization; unfortunately, however, many do not obtain an adequate collection yield. Despite the availability of plerixafor, its widespread and uniform use is limited by its cost, and consequently, many institutions have adopted various risk-adapted algorithms. We report our mobilization experience as we have modified our plerixafor algorithm to a more liberal one, with the expectation of greater collection efficiency and mobilization success with higher plerixafor use. A total of 344 mobilization attempts were analyzed over 3 time periods and using 3 different peripheral blood CD34⁺ cell counts to guide plerixafor use: <15/µL (n = 66), <20/µL (n = 130), and <40/µL (n = 148). The primary endpoints were evaluation of changes in mean plerixafor utilization and apheresis days and assessment of the impact on overall mobilization costs. Secondary endpoints were a description of the impact of lenalidomide use on mobilization and evaluation of the rate of mobilization failure. We found that mean plerixafor use increased from 1.32 to 1.65 to 1.74 doses per mobilization (P = .026) and the mean days of apheresis decreased from 2.15 to 2.17 to 1.89 days per mobilization for the <15/µL, <20/µL, and <40/µL cohorts, respectively (P = .011). The combined cost of plerixafor and apheresis procedures at a threshold of 40/µL is close to that at a threshold of 15/µL, while saving 26 apheresis days per 100 patients. In general, there were low rates of mobilization failure across all thresholds. Patients who received more than 6 cycles of lenalidomide demonstrated impaired mobilization and required more apheresis sessions (P < .013) and greater plerixafor use (P < .001) to achieve target stem cell yields. Overall, using plerixafor in patients with MM, with a day 4 pCD34 count of <40/µL is a reasonable and cost-effective strategy to optimize apheresis utilization.

Mobilization and collection of cells in the hematologic compartment for cellular therapies: Stem cell collection with G-CSF/plerixafor, collecting lymphocytes/monocytes

An essential and influential first step in all cellular therapies is collecting donor or patient cells. In hematopoietic progenitor cell transplantation, autologous or allogeneic hematopoietic progenitor cells (HPCs) are collected from either the bone marrow or the peripheral blood. Peripheral blood collection by apheresis requires mobilization with chemotherapy, granulocyte colony stimulating factor (G-CSF), plerixafor, or a combination. The modalities of mobilization and collection each carry a unique set of risks and benefits for both the donor and the recipient. In other types of cell therapy, most notably chimeric antigen receptor T cells, lymphocytes or monocytes are collected from the peripheral blood. The risks of collecting these cells by apheresis are similar to HPCs, but less is known about the composition, timing and qualitative cell characteristics which contribute to an optimal collection. Here, we review the mobilization and collection of HPCs and the collection of lymphocytes and monocytes. Donor safety is of primary importance when collecting material for any type of cell therapy. Every aspect of mobilization and collection can be studied and potentially optimized to improve patient outcomes.

Comparison and cost analysis of three protocols for mobilization and apheresis of haematopoietic progenitor cells

INTRODUCTION

Autologous bone marrow transplantation is a component of the malignant hemopathy therapy. The preferred mobilization and collection method is apheresis. The aim of this study is to compare three protocols analyzing the effect of plerixafor, higher dose of G-CSF and large volume leukapheresis (LVL).

MATERIALS AND METHODS

A retrospective cohort study including 119 patients referred for mobilization. Three protocols were compared: (a) G-CSF 10 μg/kg/day subcutaneous (sc) × 4 days mobilizing 1 to 1.5 blood volumes. (b) G-CSF 10 μg/kg/day sc × 4 days + plerixafor 0.24 mg/kg/day sc preventively or as a rescue agent mobilizing 1 to 1.5 blood volumes. (c) G-CSF 20 μg/kg/day sc × 4 days ± plerixafor 0.24 mg/kg/day sc preventively or as a rescue agent mobilizing 3 to 4 blood volumes.

RESULTS

The average number of days of apheresis was reduced to 1.37 with protocol 3. The average cost per patient was reduced by 67% compared with protocol 2 and increased by only 5% compared with protocol 1, reducing the failure rate to 0%.

CONCLUSION

Adding preemptive or rescue plerixafor (protocol 2) to G-CSF 10 μg/kg/day alone (protocol 1) did not improve the days of apheresis nor the number of CD34+ cells collected but had higher cost and failure rate. Using LVL, plerixafor and G-CSF 20 μg/kg/day (protocol 3) decreased the number of sessions to 1.37, reduced the failure rate to 0% and led to a significant increase in the number of CD34+ cells collected without toxicity and with a similar cost to protocol 1.

Predicting failure of hematopoietic stem cell mobilization before it starts: the predicted poor mobilizer (pPM) score

Predicting mobilization failure before it starts may enable patient-tailored strategies. Although consensus criteria for predicted PM (pPM) are available, their predictive performance has never been measured on real data. We retrospectively collected and analyzed 1318 mobilization procedures performed for MM and lymphoma patients in the plerixafor era. In our sample, 180/1318 (13.7%) were PM. The score resulting from published pPM criteria had sufficient performance for predicting PM, as measured by AUC (0.67, 95%CI: 0.63-0.72). We developed a new prediction model from multivariate analysis whose score (pPM-score) resulted in better AUC (0.80, 95%CI: 0.76-0.84, p < 0001). pPM-score included as risk factors: increasing age, diagnosis of NHL, positive bone marrow biopsy or cytopenias before mobilization, previous mobilization failure, priming strategy with G-CSF alone, or without upfront plerixafor. A simplified version of pPM-score was categorized using a cut-off to maximize positive likelihood ratio (15.7, 95%CI: 9.9-24.8); specificity was 98% (95%CI: 97-98.7%), sensitivity 31.7% (95%CI: 24.9-39%); positive predictive value in our sample was 71.3% (95%CI: 60-80.8%). Simplified pPM-score can "rule in" patients at very high risk for PM before starting mobilization, allowing changes in clinical management, such as choice of alternative priming strategies, to avoid highly likely mobilization failure.

Platelet Count before Peripheral Blood Stem Cell Mobilization Is Associated with the Need for Plerixafor But Not with the Collection Result

BACKGROUND

A low platelet count before mobilization has recurrently been identified as risk factor for poor mobilization.

METHODS

To determine the relevance of this finding for peripheral blood stem cell (PBSC) mobilization, including pre-emptive or rescue plerixafor in the case of poor mobilization, we retrospectively analyzed all patients undergoing PBSC collection at our institution between January 2014 and December 2015 (n = 380).

RESULTS

In total, 99% of the patients (377/380) successfully collected a minimum of 2 × 106 CD34+ cells/kg body weight sufficient for a single transplant. Rescue or pre-emptive plerixafor was administered to 11% of the patients (42/380). No correlations between the platelet count before mobilization and the number of peripheral blood CD34+ cells or the CD34+ cell collection result were detected in the entire population or the subgroups according to diagnosis (newly diagnosed multiple myeloma, relapsed multiple myeloma, lymphoma, amyloid light-chain amyloidosis, sarcoma, or germ cell tumor). However, patients requiring pre-emptive or rescue plerixafor had a significantly lower platelet count before mobilization (217/nl vs. 245/nl; p = 0.004).

CONCLUSION

With the current state of the art PBSC mobilization strategies, the platelet count before mobilization was not associated with the CD34+ cell collection result but was associated with the need for pre-emptive or rescue application of plerixafor.

Recombinant human thrombopoietin improves the efficacy of intermediate-dose cyclophosphamide plus granulocyte colony-stimulating factor in mobilizing peripheral blood stem cells in patients with multiple myeloma: A cohort study

The combination of intermediate-dose cyclophosphamide (ID-CTX) and granulocyte colony-stimulating factor (G-CSF) fails to mobilize peripheral blood stem cells (PBSCs) in approximately 20% of treated patients with multiple myeloma (MM).In this cohort study, patients with MM underwent PBSC mobilization with either an ID-CTX plus G-CSF plus recombinant human thrombopoietin (rhTPO) regimen (72 patients; TPO group), or an ID-CTX plus G-CSF regimen (70 patients; non-TPO group).In the TPO group, the median CD34+ harvest was 5.36 × 10 per kg of body weight (0.50-22.39 × 10 per kg of body weight), with a harvest success rate of 91.7% (66/72), and an excellence rate of 55.6% (40/72). In the non-TPO group, the median CD34+ harvest was 3.30 × 10 per kg of body weight (0.20-21.14 × 10 per kg of body weight), with a harvest success rate of 75.7% (53/70), and an excellence rate of 25.7% (18/70). The median count of the CD34+ cells collected, success rate of collection, and excellence rate of collection were significantly higher in the TPO group than in the non-TPO group (P=.0001, P=.01, and P = .0001, respectively). Time to granulocyte and platelet engraftment was faster among patients in the TPO group than that in those from the non-TPO group. No platelet engraftment delay (>21 days) was observed among patients in the TPO group, while 3 patients in the non-TPO group displayed delayed platelet engraftment.Adding rhTPO to the ID-CTX chemotherapy plus G-CSF regimen improved treatment efficacy in mobilizing PBSCs for autologous hematopoietic stem cell transplantation.

Management of mobilization failure in 2017

In contemporary clinical practice, almost all allogeneic transplantations and autologous transplantations now capitalize on peripheral blood stem cells (PBSCs) as opposed to bone marrow (BM) for the source of stem cells. In this context, granulocyte colony-stimulating factor (G-CSF) plays a pivotal role as the most frequently applied frontline agent for stem cell mobilization. For patients classified as high-risk, chemotherapy based mobilization regimens can be preferred as a first choice and it is notable that this also used for remobilization. Mobilization failure occurs at a rate of 10%-40% with traditional strategies and it typically leads to low-efficiency practices, resource wastage, and delayed in treatment intervention. Notably, however, several factors can impact the effectiveness of CD34⁺ progenitor cell mobilization, including patient age and medical history (prior chemotherapy or radiotherapy, disease and marrow infiltration at the time of mobilization). In recent years, main (yet largely ineffective) approach was to increase G-CSF dose and add SCF, but novel and promising pathways have been opened up by the synergistic impact of a reversible inhibitor of CXCR4, plerixafor, with G-CSF. The literature shows to its favorable results in upfront and failed mobilizers, and it is necessary to use plerixafor (or equivalent agents) to optimize HSC harvest in poor mobilizers. Different CXCR4 inhibitors, growth hormone, VLA4 inhibitors, and parathormone, have been cited as new agents for mobilization failure in recent years. In view of the above considerations, the purpose of this paper is to examine the mobilization of PBSC while focusing specifically on poor mobilizers.

Preemptive plerixafor injection added to pegfilgrastim after chemotherapy in non-Hodgkin lymphoma patients mobilizing poorly

Filgrastim is usually combined with chemotherapy to mobilize hematopoietic progenitor cells in non-Hodgkin lymphoma (NHL) patients. Limited information is available on the efficacy of a preemptive plerixafor (PLER) injection in poor mobilizers after chemotherapy and pegfilgrastim. In this prospective study, 72 patients with NHL received chemotherapy plus pegfilgrastim, and 25 hard-to-mobilize patients received also PLER. The usefulness and efficacy of our previously developed algorithm for PLER use in pegfilgrastim-containing mobilization regimen were evaluated as well as the graft cellular composition, hematological recovery, and outcome after autologous stem cell transplantation (auto-SCT) according to the PLER use. A median 3.4-fold increase in blood CD34⁺ cell counts was achieved after the first PLER dose. The minimum collection target was achieved in the first mobilization attempt in 66/72 patients (92%) and 68 patients (94%) proceeded to auto-SCT. An algorithm for PLER use was fulfilled in 76% of the poor mobilizers. Absolute numbers of T-lymphocytes and NK cells were significantly higher in the PLER group, whereas the number of CD34⁺ cells collected was significantly lower. Early neutrophil engraftment was slower in the PLER group, otherwise hematological recovery was comparable within 12 months from auto-SCT. No difference was observed in survival according to the PLER use. Chemotherapy plus pegfilgrastim combined with preemptive PLER injection is an effective and convenient approach to minimize collection failures in NHL patients intended for auto-SCT. A significant effect of PLER on the graft cellular composition was observed, but no difference in outcome after auto-SCT was detected.

UK consensus statement on the use of plerixafor to facilitate autologous peripheral blood stem cell collection to support high-dose chemoradiotherapy for patients with malignancy

Plerixafor is a CXC chemokine receptor (CXCR4) antagonist that mobilizes stem cells in the peripheral blood. It is indicated (in combination with granulocyte-colony stimulating factor [G-CSF]) to enhance the harvest of adequate quantities of cluster differentiation (CD) 34+ cells for autologous transplantation in patients with lymphoma or multiple myeloma whose cells mobilize poorly. Strategies for use include delayed re-mobilization after a failed mobilization attempt with G-CSF, and rescue or pre-emptive mobilization in patients in whom mobilization with G-CSF is likely to fail. Pre-emptive use has the advantage that it avoids the need to re-schedule the transplant procedure, with its attendant inconvenience, quality-of-life issues for the patient and cost of additional admissions to the transplant unit. UK experience from 2 major centers suggests that pre-emptive plerixafor is associated with an incremental drug cost of less than £2000 when averaged over all patients undergoing peripheral blood stem cell (PBSC) transplant. A CD34+ cell count of <15 µl^-1 at the time of recovery after chemomobilization or after four days of G-CSF treatment, or an apheresis yield of <1 × 10⁶ CD34+ cells/kg on the first day of apheresis, could be used to predict the need for pre-emptive plerixafor.

Autologous Stem Cell Mobilization and Collection

Peripheral blood stem cell collection is an effective approach to obtain a hematopoietic graft for stem cell transplantation. Developing hematopoietic stem/progenitor cell (HSPC) mobilization methods and collection algorithms have improved efficiency, clinical outcomes, and cost effectiveness. Differences in mobilization mechanisms may change the HSPC content harvested and result in different engraftment kinetics and complications. Patient-specific factors can affect mobilization. Incorporating these factors in collection algorithms and improving assays for evaluating mobilization further extend the ability to obtain sufficient HSPCs for hematopoietic repopulation. Technological advance and innovations in leukapheresis have improved collection efficiency and reduced adverse effects.

Mobilization, Isolation and Characterization of Stem Cells from Peripheral Blood: a Systematic Review

Objectives

The purpose of this article is to systematically review the methods of mobilization, isolation and characterization of stem cells from peripheral blood and to discuss their potential therapeutic applications for bone tissue regeneration.

Material and Methods

An electronic literature search was performed through MEDLINE (PubMed) electronic database. The search was restricted to English language articles published during the last 10 years, from January 2006 to November 2016.

Results

In total, 37 literature sources were reviewed, and 11 of the most relevant articles that are suitable to the criteria were selected. Articles were analysed with data on animals and humans for mobilization, isolation and characterization of stem cells from peripheral blood. From the examination of selected articles, the mobilization materials, side effects, alternatives and factors affecting the extracted amount of mesenchymal stem cells (MSC) from mobilized peripheral blood of healthy individuals, as well as characterization of mobilized MSC were reviewed in this article.

Conclusions

Bone tissue engineering is a potential alternative strategy in bone regeneration and bone defect repair, however, insufficiency data display in the literature on potential therapeutic applications of peripheral blood stem cells for bone tissue regeneration.

How to manage poor mobilizers for high dose chemotherapy and autologous stem cell transplantation?

Today, peripheral blood stem cells are the preferred source of stem cells over bone marrow. Therefore, mobilization plays a crutial role in successful autologous stem cell transplantation. Poor mobilization is generally defined as failure to achieve the target level of at least 2×10⁶ CD34⁺ cells/kg body weight. There are several strategies to overcome poor mobilization: 1) Larger volume Leukapheresis (LVL) 2) Re-mobilization 3) Plerixafor 4) CM+Plerixafor (P)+G-CSF and 5) Bone Marrow Harvest. In this review, the definitions of successful and poor mobilization are discussed. Management strategies for poor mobilization are defined. The recent research on new agents are included.

Mobilization of hematopoietic progenitor cells for autologous transportation: consensus recommendations

Selected patients with certain hematological malignancies and solid tumors have the potential to achieve long-term survival with autologous hematopoietic progenitor cell transplant. The collection of these cells in peripheral blood avoids multiple bone marrow aspirations, results in faster engraftment and allows treatment of patients with infection, fibrosis, or bone marrow hypocellularity. However, for the procedure to be successful, it is essential to mobilize a sufficient number of progenitor cells from the bone marrow into the blood circulation. Therefore, a group of Brazilian experts met in order to develop recommendations for mobilization strategies adapted to the reality of the Brazilian national health system, which could help minimize the risk of failure, reduce toxicity and improve the allocation of financial resources.

How do we mobilize and collect autologous peripheral blood stem cells?

Autologous stem cell transplantation (ASCT) with mobilized peripheral blood stem cells (PBSCs) has become a widely applied therapeutic approach for many hematologic and nonhematologic diseases. Adequate PBSC mobilization is critical to the success of ASCT. However, many factors can contribute to poor mobilization. Plerixafor is an effective yet costly adjunct agent that has been increasingly used to improve mobilization in a variety of diagnoses and clinical settings. However, to achieve both optimal cell collection yields and cost-effectiveness, the role of plerixafor in PBSC mobilization needs to be well defined in terms of triggers for initiating its use and criteria for monitoring response. As one of the largest hematopoietic transplant centers in the country, we have developed an approach to PBSC mobilization and collection that incorporates patient laboratory assessments, monitoring of the collection yields, and judicious use of plerixafor as well as various patient support and education programs. These measures have resulted in an increase in our collection success rate and a decrease in the mean number of collection days. In this article we describe our approach to autologous PBSC mobilization and collection. Pertinent reports in the literature are also reviewed and discussed.

Plerixafor for autologous stem-cell mobilization and transplantation for patients in Ontario

BACKGROUND

High-dose chemotherapy with autologous stem-cell transplantation (asct) is an accepted part of standard therapy for patients with hematologic malignancies. Usually, stem-cell mobilization uses granulocyte colony-stimulating factor (g-csf); however, some patients are not able to be mobilized with chemotherapy and g-csf, and such patients could be at higher risk of failing mobilization. Plerixafor is a novel mobilization agent that is absorbed quickly after subcutaneous injection and, at the recommended dose of 0.24 mg/kg, provides a sustained increase in circulating CD34+ cells for 10-18 hours. The main purpose of the present report was to evaluate the most current evidence on the efficacy of plerixafor in enhancing hematopoietic stem-cell mobilization and collection before asct for patients in Ontario so as to make recommendations for clinical practice and to assist Cancer Care Ontario in decision-making with respect to this intervention.

METHODS

The medline and embase databases were systematically searched for evidence from January 1996 to March 2015, and the best available evidence was used to draft recommendations relevant to the efficacy of plerixafor in enhancing hematopoietic stem-cell mobilization and collection before asct. Final approval of this practice guideline report was obtained from both the Stem Cell Transplant Steering Committee and the Report Approval Panel of the Program in Evidence-Based Care.

RECOMMENDATIONS

These recommendations apply to adult patients considered for asct: ■ Adding plerixafor to g-csf is an option for initial mobilization in patients with non-Hodgkin lymphoma or multiple myeloma who are eligible for asct when chemotherapy cannot be used and only g-csf mobilization is available.■ For patients with a low peripheral blood CD34+ cell count (for example, <10/μL) at the time of anticipated stem-cell harvesting, or with an inadequate first-day apheresis collection, it is recommended that plerixafor be added to the mobilization regimen to maximize stem-cell collection and to prevent the need for remobilization.■ It is recommended that patients who have failed a previous mobilization attempt undergo remobilization with g-csf and plerixafor, with or without chemotherapy.

Decision-tree algorithm for optimized hematopoietic progenitor cell-based predictions in peripheral blood stem cell mobilization

BACKGROUND

Enumerating hematopoietic progenitor cells (HPCs) by using an automated hematology analyzer is a rapid, inexpensive, and simple method for predicting a successful harvest compared with enumerating circulating CD34+ cells. However, the optimal HPC cutoff count and the indicating factors to be considered for improved predicting have not yet been determined.

STUDY DESIGN AND METHODS

Between 2007 and 2012, a total of 189 consecutive patients who proceeded to peripheral blood stem cell (PBSC) harvesting were retrospectively recruited. Baseline characteristics were analyzed to identify the risk factors for a failed harvest, which were defined as less than 2 × 10(6) CD34+ cells/kg. Variables identified by multivariate logistic regression and correlation analysis for predicting a successful harvest were subjected to classification and regression tree (CART) analysis.

RESULTS

PBSCs were successfully harvested in 154 (81.5%) patients. An age of at least 60 years, a diagnosis of a solid tumor, at least five prior chemotherapy cycles, prior radiotherapy, and mobilization with granulocyte-colony-stimulating factor alone or high-dose cyclophosphamide were independent baseline predictors of poor mobilization. In CART analysis, patients with zero to two host risk factors and either higher HPC (≥28 × 10(6) /L) or mononuclear cell (MNC; ≥3.5 × 10(9) /L) counts were categorized as good mobilizers and their harvest success rate was 92.3%. By contrast, 30.3% of harvests were adequate in the patients with three to five host risk factors and lower HPC and MNC counts.

CONCLUSION

A CART algorithm incorporating host predictors and HPC and MNC counts improves predictions in a successful harvest and might reduce the necessity of monitoring peripheral CD34+ cells.

Plerixafor is safe and efficacious for mobilization of peripheral blood stem cells in pediatric patients

BACKGROUND

Chemotherapy followed by filgrastim is the most common strategy used to mobilize autologous peripheral blood stem cells (PBSCs) for high-dose chemotherapy and autologous stem cell transplantation. Unfortunately, this method does not always lead to adequate PBSC collection in heavily treated patients with relapsed malignancies or if multiple transplants are required. Plerixafor, a hematopoietic stem cell mobilizer that inhibits the CXCR4 chemokine receptor and blocks binding of its cognate ligand, stromal cell-derived factor-1α (SDF-1α), has been shown to be safe and efficacious in the mobilization of autologous PBSC in adults. Despite its use in adults, little evidence exists to support its use in children.

STUDY DESIGN AND METHODS

We report a retrospective review of 16 consecutive pediatric patients receiving plerixafor as part of their mobilization regimen at Cincinnati Children's Hospital Medical Center. All patients but one were given 0.24 mg/kg dose of plerixafor and the median number of plerixafor doses received was two (range, one to four doses). One patient received higher doses of plerixafor.

RESULTS

An adequate number of CD34+ cells were obtained in 14 of 16 patients (87.5%). The median number of CD34+ cells collected for patients who reached collection goal was 6 × 10(6) CD34+ cells/kg (range, 1.6 × 10(6) -12.4 × 10(6) /kg). No acute adverse events were noted to be attributable to plerixafor administration.

CONCLUSION

Our findings suggest that plerixafor use in children is safe and efficacious for the mobilization of autologous PBSCs in subjects with relapsed malignancies or requiring stem cells for multiple transplants.

Stem Cell Mobilization with G-CSF versus Cyclophosphamide plus G-CSF in Mexican Children

Fifty-six aphaereses were performed in 23 pediatric patients with malignant hematological and solid tumors, following three different protocols for PBPC mobilization and distributed as follows: A: seventeen mobilized with 4 g/m² of cyclophosphamide (CFA) and 10 μg/kg/day of granulocyte colony stimulating factor (G-CSF), B: nineteen with CFA + G-CSF, and C: twenty only with G-CSF when the WBC count exceeded 10 × 10⁹/L. The average number of MNC/kg body weight (BW)/aphaeresis was 0.4 × 10⁸ (0.1–1.4), 2.25 × 10⁸ (0.56–6.28), and 1.02 × 10⁸ (0.34–2.5) whereas the average number of CD34+ cells/kg BW/aphaeresis was 0.18 × 10⁶/kg (0.09–0.34), 1.04 × 10⁶ (0.19–9.3), and 0.59 × 10⁶ (0.17–0.87) and the count of CFU/kg BW/aphaeresis was 1.11 × 10⁵ (0.31–2.12), 1.16 × 10⁵ (0.64–2.97), and 1.12 × 10⁵ (0.3–6.63) in groups A, B, and C, respectively. The collection was better in group B versus group A (p = 0.007 and p = 0.05, resp.) and in group C versus group A (p = 0.08 and p = 0.05, resp.). The collection of PBPCs was more effective in the group mobilized with CFM + G-CSF when the WBC exceeded 10 × 10³/μL in terms of MNC and CD34+ cells and there was no toxicity of the chemotherapy.

Upfront plerixafor plus G-CSF versus cyclophosphamide plus G-CSF for stem cell mobilization in multiple myeloma: efficacy and cost analysis study

Cyclophosphamide plus G-CSF (C+G-CSF) is one of the most widely used stem cell (SC) mobilization regimens for patients with multiple myeloma (MM). Plerixafor plus G-CSF (P+G-CSF) has demonstrated superior SC mobilization efficacy when compared with G-CSF alone and has been shown to rescue patients who fail mobilization with G-CSF or C+G-CSF. Despite the proven efficacy of P+G-CSF in upfront SC mobilization, its use has been limited, mostly due to concerns of high price of the drug. However, a comprehensive comparison of the efficacy and cost effectiveness of SC mobilization using C+G-CSF versus P+G-CSF is not available. In this study, we compared 111 patients receiving C+G-CSF to 112 patients receiving P+G-CSF. The use of P+G-CSF was associated with a higher success rate of SC collection defined as ⩾5 × 10(6) CD34+ cells/kg (94 versus 83%, P=0.013) and less toxicities. Thirteen patients in the C+G-CSF arm were hospitalized owing to complications while none in the P+G-CSF group. C+G-CSF was associated with higher financial burden as assessed using institutional-specific costs and charges (P<0.001) as well as using Medicare reimbursement rates (P=0.27). Higher rate of hospitalization, increased need for salvage mobilization, and increased G-CSF use account for these differences.

A nationwide survey of the use of plerixafor in patients with lymphoid malignancies who mobilize poorly demonstrates the predominant use of the "on-demand" scheme of administration at French autologous hematopoietic stem cell transplant programs

BACKGROUND

High-dose chemotherapy supported with autologous stem cell transplantation is a standard therapeutic option for a subset of patients with lymphoid malignancies. Cell procurement is nowadays done almost exclusively through cytapheresis, after mobilization of hematopoietic stem and progenitor cells (HSPCs) from the marrow to peripheral blood (PB). The egress of HSPCs out of hematopoietic niches occurs in various physiologic or nonhomeostatic situations; pharmacologic approaches include the administration of acutely myelosuppressive agents or hematopoietic growth factors such as recombinant human granulocyte-colony-stimulating factor (rHuG-CSF). The introduction of plerixafor, a first-of-its-class molecule that reversibly inhibits the interaction between the chemokine CXCL-12 (also known as SDF-1) and its receptor CXCR-4, has offered new opportunities for the so-called "poor mobilizers" who achieve insufficient mobilization and/or collection with conventional approaches.

STUDY DESIGN AND METHODS

Because of the lack of consensus on a definition for poor mobilizers and the relatively high cost of plerixafor, French competent authorities have mandated a postmarketing survey on its use in routine practice.

RESULTS AND CONCLUSION

We report here the results of this nationwide survey that confirms the clinical efficacy of plerixafor, even in the subset of patients who barely increased PB CD34+ cell count in response to rHuG-CSF-containing mobilization regimen. Furthermore, analysis of this registry showed that despite heterogeneity in medical practices, the early-"on-demand" or "preemptive"-introduction of plerixafor was widely used and did not result in an excess of prescriptions, beyond its expected use at the time when marketing authorization was granted.

The potential of cytotherapeutics in hematologic reconstitution and in the treatment and prophylaxis of graft-versus-host disease. Chapter I: current practice and remaining unmet medical needs

Hematopoietic stem cell transplantation is a life-saving treatment for inherited anemias, immunodeficiencies or hematologic malignancies. When using partially HLA-matched allografts, a major complication is graft-versus-host disease (GvHD). The ideal attributes of a transformational new GvHD treatment include improved survival, decreased corticosteroids, decreased antifungals, improved quality of life through decreased infections, reduced number of hospital stay days, reduced risks of developing chronic GvHD impact on lower GI tract and liver, prophylactic benefits and decreased GvHD relapses, but, in the case of cancer, without negatively impacting beneficial graft-versus-tumor effects. The current practice of hematopoietic stem cell transplantation, its incidence and its unmet medical needs are reviewed here and discussed.

Predicting poor peripheral blood stem cell collection in patients with multiple myeloma receiving pre-transplant induction therapy with novel agents and mobilized with cyclophosphamide plus granulocyte-colony stimulating factor: results from a Gruppo Italiano Malattie EMatologiche dell'Adulto Multiple Myeloma Working Party study

INTRODUCTION

A still not well defined proportion of patients with multiple myeloma (MM) and eligible for autologous stem cell transplantation (AuSCT) fails to mobilize CD34+ peripheral blood stem cells (PBSC) at all or to collect an adequate number for a safe procedure or sufficient for multiple transplants. These so-called "poor-mobilizers" are difficult to be predicted, due to marked difference across previous heterogeneous studies.

METHODS

We aimed to develop a method based on simple clinical parameters for predicting unsuccessful (<2×10(6)/kg) or sub-optimal (<5×10(6)/kg) collections of CD34+ PBSC in newly diagnosed MM patients eligible for AuSCT, treated with novel agents and receiving an homogeneous mobilizing therapy with cyclophosphamide and granulocyte-colony stimulating factor (G-CSF). To this purpose, 1,348 patients enrolled in five consecutive Italian clinical trials were retrospectively analysed. Age, baseline low peripheral blood cell counts, use of lenalidomide, and haematological toxicity developed during induction were taken into account as possible factors associated with poor mobilization.

RESULTS

Overall, 280 patients (20.8%) showed either sub-optimal (167 patients, 12.4%) or unsuccessful (113 patients, 8.4%) collections. All analysed parameters negatively influenced the procedure, but only age and haematological toxicity during induction maintained their significance at multivariate analysis. Based on ordinal logistic regression model, we constructed a risk heat-map where the four parameters were pooled and weighted according to their relevance as single or combined variables. This model was predictive for different probabilities of failure, suboptimal or optimal outcomes.

CONCLUSIONS

We found that about one fifth of newly diagnosed MM fails to collect an adequate number of PBSC. Our model, based on a large group of patients treated frontline with novel agents and receiving the most popular mobilizing approach currently employed in Europe, is applicable in individual subjects and may contribute to the early identification of "poor mobilizer" phenotypes.

Plerixafor on demand in ten healthy family donors as a rescue strategy to achieve an adequate graft for stem cell transplantation

BACKGROUND

In allogeneic hematopoietic stem cell (HSC) transplantation, the collection of an appropriate number of HSCs while maintaining a high level of safety for healthy donors is fundamental. Inadequate HSC mobilization can be seen with the standard use of granulocyte-colony-stimulating (G-CSF). Plerixafor (PL) is a chemokine receptor CXC Type 4-stromal-derived factor 1 inhibitor; its HSC-mobilizing properties are synergistic with G-CSF in poor mobilizing patients. The use of PL as adjuvant or alternative to G-CSF in healthy donors has shown a good safety profile but is so far off-label.

STUDY DESIGN AND METHODS

We report 10 healthy HSC donors treated with PL because of insufficient response to G-CSF alone or contraindication to G-CSF. Eight donors did not mobilize enough CD34+ cells with G-CSF alone because poor mobilizers or because insufficient HSCs were harvested according to the clinical need of the patient; in two cases G-CSF administration and marrow harvest were unfeasible or contraindicated in the donor.

RESULTS

The use of PL for mobilization increased the number of circulating CD34+ cells by 2.8-fold and the CD34+/kg collection by 3.0-fold. Only mild adverse events were reported (bone pain or discomfort) and not univocally attributable to PL. Rate of engraftment and graft-versus-host disease were similar to those seen in recipients of grafts from G-CSF only-mobilized donors.

CONCLUSION

We exposed 10 allogeneic donors to mobilization with PL. PL was well tolerated in all cases and ensured procurement of an adequate graft for transplantation resulting in a normal hematopoietic engraftment.

Plerixafor: what we still have to learn

Plerixafor, a hematopoietic stem cell mobilizer, is indicated in combination with G-CSF to mobilize hematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation in patients with non-Hodgkin's lymphoma and multiple myeloma. Current evidence suggests that the addition of plerixafor with chemotherapy plus G-CSF is safe and effective in the large majority of the patients with low blood CD34(+) cell count after mobilization and/or poor yield after the first collection. Nevertheless, there are several questions strongly debated, and in this paper, we would like to identify areas of possible future use and development of the drug.

The prognostic impact of peripheral blood progenitor cell dose following high-dose therapy and autologous stem cell transplant for hematologic malignancies

High-dose chemotherapy (HDT) followed by autologous peripheral blood progenitor cell transplant (PBPCT) has become a standard intervention in certain clinical settings of hematologic malignancies, particularly multiple myeloma and relapsed/refractory lymphoma. While the minimal required PBPCs infused, as defined by number of CD34 + cells, has been relatively well delineated for adequate hematopoietic recovery post-HDT, optimal PBPC dose has not been clearly defined. This is particularly relevant in the context of retrospective data suggesting improved survival outcomes with increased PBPC doses. The potential confounding of these data as they relate to disease risk is discussed within this review. Additionally, other retrospective data have suggested that enhanced quantitative lymphocyte subset reconstitution post-HDT-PBPCT may confer progression-free and overall survival advantage. These reported series herein reviewed may inform discussion of future, prospective clinical trials with the intent of defining optimal autologous PBPC dose following HDT, especially as it may relate to metrics beyond hematopoietic recovery.