Upfront use of plerixafor and granulocyte-colony stimulating factor (GCSF) for stem cell mobilization in patients with multiple myeloma: efficacy and analysis of risk factors associated with poor stem cell collection efficiency

Effect of prior lenalidomide or daratumumab exposure on hematopoietic stem cell collection and reconstitution in multiple myeloma

BACKGROUND

The roles of Lenalidomide (Len) and Daratumumab (Dara) in multiple myeloma treatment are well-established, yet their influences on hematopoietic stem cell harvesting and reconstitution remain disputed.

METHODS

We conducted a systematic database review to identify cohort studies or RCTs evaluating the effect of the use of Len or Dara on hematopoietic stem cell collection and peripheral blood count recovery in multiple myeloma patients. Effects on hematopoietic collection or reconstitution were estimated by comparing standardized mean differences (SMD) and mean differences (MD), or median differences.

RESULTS

Eighteen relevant studies were identified, summarizing mobilization results. For Len, data from 13 studies were summarized, including total CD34+ cell yield, collection failure rate, and time to neutrophil and platelet engraftment. Results indicated that Len exposure led to decreased stem cell collection [SMD=-0.23, 95% CI (-0.34, -0.12)]. However, collection failure (<2×106) could be mitigated by plerixafor [OR=2.14, 95% CI (0.96, 4.77)]. For Dara, two RCTs and three cohort studies were included, showing that Dara exposure resulted in a reduction in total stem cells even with optimized plerixafor mobilization [SMD=-0.75, 95% CI (-1.26, -0.23)], and delayed platelet engraftment recovery [MD=1.20, 95% CI (0.73, 1.66)].

CONCLUSIONS

Our meta-analysis offers a comprehensive view of Len and Dara's impacts on hematopoietic stem cell collection and reconstitution in multiple myeloma. Len usage could lead to reduced stem cell collection, counteracted by plerixafor mobilization. Dara usage could result in diminished stem cell collection and delayed platelet engraftment.

Mobilization Strategies in Myeloma Patients Intended for Autologous Hematopoietic Cell Transplantation

Background

Multiple myeloma is currently the leading indication for autologous hematopoietic cell transplantation (AHCT). A prerequisite for AHCT is mobilization and collection of adequate blood graft to support high-dose therapy. Current mobilization strategies include granulocyte colony-stimulating factor (G-CSF) alone or in combination with chemotherapy most commonly cyclophosphamide (CY). More recently, plerixafor has become into agenda especially in patients who mobilize poorly. In the selection of a mobilization method, several factors should be considered.

Summary

Preplanned collection target is important as G-CSF plus plerixafor is more effective in the mobilization of CD34+ cells than G-CSF alone. On the other hand, CY plus G-CSF is superior to G-CSF only mobilization. Previous therapy and age of the patients are important considerations as G-CSF alone may not be effective enough in patients with risk factors for poor mobilization. These factors include extensive lenalidomide exposure, irradiation to bone marrow-bearing sites, higher age, or a previous mobilization failure. Also, local preferences and experiences as well as the number of apheresis needed are important issues as well as cost-effectiveness considerations. Mobilization method used may have implication for cellular composition of collected grafts, which might have an impact on posttransplant events such as hematologic and immune recovery in addition to also potential long-term outcomes.

Key Message

Currently, G-CSF alone and preemptive plerixafor if needed might be considered as a standard mobilization strategy in MM patients intended for AHCT.

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.

Successful autologous peripheral blood stem cell collection using large volume leukapheresis in patients with very low or undetectable peripheral blood CD34+ progenitor cells

Autologous stem cell transplantation provides some patients with hematolymphoid and solid organ malignancies an opportunity for cure. Management of peripheral hematopoietic stem cell (HSC) collections differs among institutions, especially if a very low pre-procedure peripheral blood CD34+ cell count (PBCD34) is demonstrated. This study retrospectively analyzed results of large-volume peripheral HSC collections in 91 patients over approximately two years. Fifteen patients with PBCD34 < 10 × 10e6/l (eleven with undetectable PBCD34) were compared to 76 patients with higher counts on the first collection day (adequate mobilizers). The poor mobilizer group had significantly lower pre-collection WBC and platelet counts as well as collection yields. However, most patients with PBCD34 < 10 × 10e6/l (80 %) collected the minimum target for HSC transplant (2.0 × 10e6 CD34+ cells/kg) in <5 consecutive days of collection, and those who did collect the minimum successfully underwent autologous transplantation, with hematopoietic engraftment and long-term survival comparable to the adequate mobilizers. Successful HSC collection may often be achieved regardless of d 1 PBCD34 counts.

Mobilization of Hematopoietic Stem Cells into Peripheral Blood for Autologous Transplantation Seems Less Efficacious in Poor Mobilizers with the Use of a Biosimilar of Filgrastim and Plerixafor: A Retrospective Comparative Analysis

Introduction

Biosimilars of granulocyte colony-stimulating factors (G-CSF) have shown similar efficacy to originator filgrastim (Neupogen® [NEU]; Amgen Inc.) as prophylaxis in neutropenia and in the mobilization of stem cells in patients receiving combination chemotherapy with G-CSF.

Methods

This was a retrospective study in which the characteristics of stem cell mobilization treated with a G-CSF alone were compared in 216 patients and 56 donors. The two G-CSF compared were NEU and the biosimilar filgrastim Zarzio® (Sandoz GmbH) (referred to hereafter as BIO). Primary objectives were mobilization rate (minimum of 10 × 10³/ml CD34+ on day 4 of treatment [day +4]) and use of the immunostimulant plerixafor (PLEX) in each group.

Results

The general characteristics of the patients receiving NEU (n = 138) and those receiving BIO (n = 78) did not differ significantly. PLEX was used in 24% of BIO patients and in 25.7% of NEU patients. The median CD34+ cell count on day +4 was significantly lower in BIO patients who needed PLEX than in those who did not (2.4 vs. 4.8 × 10³/ml; p = 0.002), as was the final CD34+ cell count (2.5 vs. 3.3 × 10⁶/kg; p 0.03). Mobilization failure rate was higher in the BIO group than in the NEU group (20 vs. 0%; p = 0.01). With respect to donors, more than one apheresis was needed in three BIO donors, one of them with PLEX. The use of BIO was the only risk factor for mobilization failure in patients who needed PLEX (hazard ratio 10.3; 95% confidence interval 1.3–77.8).

Conclusion

The study revealed that BIO had a lower efficacy for stem cell mobilization when the only treatment was G-CSF, especially in poor mobilizers needing PLEX.

Preemptive and Upfront Plerixafor: Safe and Effective Strategy for Patients Undergoing Autologous Stem Cell transplant and at High Risk for Mobilization Failure

Introduction: Approximately 10%–30% of patients are unable to collect the minimum number of stem cells to support high-dose chemotherapy and autologous stem cell transplant (hematopoietic stem cell transplantation). Plerixafor alone or in combination with granulocyte colony-stimulating factor (G-CSF) has been shown to significantly increase the CD34 cell collection, especially in patients who failed their initial harvest strategy. This is a retrospective study of 17 preselected patients (relapsed lymphoma and myeloma), who were considered to have high risk of mobilization failure and who had undergone upfront and preemptive plerixafor mobilization. Patients and Methods: The mobilization protocol consisted of G-CSF (10–15 μg/kg) subcutaneously daily for 4 days before the initiation of plerixafor on evening of day 4. The patients then underwent apheresis on day 5. Results: Among 17 patients who underwent apheresis, 16 (93%) yielded the minimum required cell collection of ≥2 × 106 CD34+ cells/kg in a single apheresis session (2 days). Out of these 16 patients, 8 (53%) patients achieved the minimum target dose in a single day. Eight (50%) of all patients achieved the optimum target cell collection in a single apheresis session. Out of these eight patients, five (62%) patients collected optimum yield in a single day. Conclusion: Plerixafor is safe and effective if used upfront and preemptively for patients in whom mobilization of stem cells is considered to be a problem.

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.

The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature.

Poor mobilizer and its countermeasures

Mobilization failure is a major concern in patients undergoing hematopoietic cell transplantation, especially in an autologous setting, as almost all donor harvests can be accomplished with granulocyte-colony stimulating factor (G-CSF) alone. Poor mobilizers, defined as those with a peripheral blood CD34⁺ cell count ≤20 cells/μl after mobilization preceding apheresis is a significant risk factor for mobilization failure. We recommend preemptive plerixafor plus G-CSF (filgrastim, 10 μg/kg daily) as a first mobilization strategy, which yields sufficient peripheral blood progenitor cells (PBPCs) in almost all patients and avoids otherwise unnecessary remobilization. Preemptive plerixafor is administered in patients with a day-4 peripheral blood CD34⁺ count <15, depending on the disease and the target PBPC amount. Cyclophosphamide is reserved for patients who fail the first PBPC collection. We recommend second mobilization for patients who could not achieve a sufficient PBPC amount with the first mobilization. In these patients, a second attempt with plerixafor plus G-CSF or mobilization with plerixafor in combination with cyclophosphamide and G-CSF is recommended. Increased dose and/or twice daily administration of G-CSF can be considered.

Dose capping of plerixafor in patients weighing more than 100 kg at one vial led to successful mobilization outcomes and significant cost savings

BACKGROUND

Plerixafor is frequently used as an adjunct agent to improve mobilization of peripheral blood stem cells in many clinical settings. However, its high cost (>$8000 per single-use 24-mg vial) is a significant concern. The manufacturer-recommended dose is 0.24 mg/kg. Therefore, patients weighing more than 100 kg would require a second vial, thus doubling the drug cost per dose. We implemented a policy of capping the dose of plerixafor at 24 mg, or one vial, for patients weighing more than 100 kg. This retrospective study compares the mobilization of patients more than 100 kg who received capped doses, with historical control patients who received full, uncapped doses.

STUDY DESIGN AND METHODS

Consecutive, eligible patients weighing more than 100 kg who received capped (n = 47) and full doses of plerixafor (n = 40) were identified. Plerixafor was given up-front, as a rescue agent due to suboptimal mobilization, or during remobilization. Baseline characteristics and mobilization data were collected and compared.

RESULTS

Patients in the two groups showed comparable baseline characteristics. They collected similar total numbers of CD34+ cells/kg (median, 4.08 × 10⁶ vs. 3.36 × 10⁶ CD34+ cells/kg; p = 0.86) and achieved comparable collection success rates as defined by collecting more than 2.0 × 10⁶ CD34+ cells/kg (98% vs. 90%, p = 0.21). However, patients who received capped doses required only half of the number of vials of plerixafor (median, 3 vials vs. 6 vials; p < 0.0001).

CONCLUSION

Dose capping plerixafor at 24 mg for patients more than 100 kg is a cost-effective strategy, which achieved comparable mobilization outcomes and reduced the total number of vials of plerixafor used by half.

Chemical Stability of Plerixafor after Opening of Single-Use Vial

BACKGROUND

The addition of the immunostimulant plerixafor to the current standard-of-care regimens of granulocyte colony-stimulating growth factor with or without chemotherapy has improved clinical results in terms of successful stem cell mobilization and the outcomes of stem cell transplant in various settings. With this medical innovation has come an added financial cost for institutions where stem cell transplants are routinely performed, and there may be a further financial burden when the contents of partial vials of the drug are wasted, given that plerixafor vials (Mozobil, Sanofi-Aventis Canada Inc) are currently deemed suitable only for single use.

OBJECTIVE

To determine whether the portion of plerixafor remaining in an opened vial of the Mozobil product after administration of a single dose is chemically stable, by comparison with the original product.

METHODS

Stability testing of partial drug contents of an opened vial, stored at room temperature or under refrigeration (4°C), was conducted using liquid chromatography-tandem mass spectrometry analysis. The mean concentration of plerixafor (μmol/L), standard deviation, coefficient of variation, and bias were determined on days 2, 3, 11, 17, 24, and 31. Method validation included determination of precision, sensitivity, recovery, dilution linearity, and carryover.

RESULTS

Throughout the 4-week testing period, measured plerixafor concentration in aliquots stored at room temperature and under refrigeration, tested in series over time, appeared similar. The mean residual drug concentration after initial opening was slightly, but not significantly, higher for the sample designated for storage at room temperature than the one designated for refrigerated storage (40.4 versus 39.9 μmol/L; p = 0.37).

CONCLUSIONS

Residual plerixafor after initial opening of a vial of the Mozobil product remained chemically stable for at least 2 weeks both at room temperature and under refrigeration. The results of this study provide in vitro evidence to support multiple uses, instead of single use, of vials of this drug in an aseptic, controlled environment.