Pharmacoeconomics of hematopoietic stem cell mobilization: an overview of current evidence and gaps in the literature

MEdical Database AnaLysIS of Japanese multiple myeloma patienTs with apheresis #2 (MEDALIST-2): the impact of plerixafor use on costs and healthcare resources during mobilization and stem cell transplantation

Treatment for multiple myeloma (MM) can involve apheresis to mobilize hematopoietic stem cells for later autologous stem cell transplantation (ASCT), which can become costly over time. This retrospective claims database study examined healthcare resource use and medical costs associated with plerixafor, a selective CXCR4 inhibitor that mobilizes hematopoietic stem cells and minimizes apheresis times. Medical data were sampled from Japanese MM patients between April 2017 and September 2019, after the Japanese launch of plerixafor. The study population (190 plerixafor users and 180 non-users) was identified from the Medical Data Vision database, and further stratified into those using granulocyte-colony stimulating factor in monotherapy or in combination with cyclophosphamide to trigger apheresis. A descriptive comparison of patient characteristics, healthcare resource use, and medical costs across the mobilization and ASCT phases indicated plerixafor is associated with higher average total medical costs. However, plerixafor-treated patients received fewer concomitant medications and spent less time in apheresis than non-users. A comparison of non-users with a similar analysis conducted pre-plerixafor launch (2013-2017) showed general improvements to treatment independent of plerixafor. The results of this research can inform guidelines for the role of plerixafor in balancing cost-effectiveness and drug efficacy in MM treatment.

Collection and Processing of Mobilized Mouse Peripheral Blood at Lowered Oxygen Tension Yields Enhanced Numbers of Hematopoietic Stem Cells

Mobilized peripheral blood (mPB) hematopoietic stem (HSCs) and progenitor (HPCs) cells are primary sources for hematopoietic cell transplantation (HCT). Successful HCT requires threshold numbers of high-quality HSCs to reconstitute hematopoiesis long-term. Nevertheless, considerable percentages of patients and healthy donors fail to achieve required thresholds of HSCs with current mobilization regimens. In this present study we demonstrate that similar to mouse bone marrow (BM) and human cord blood, collection and processing of mouse Granulocyte Colony Stimulating Factor (G-CSF)-, AMD3100/Plerixafor- or G-CSF plus AMD3100/Plerixafor-mobilized HSCs in 3% O₂ results in enhanced numbers of rigorously-defined phenotypic and for G-CSF - and G-CSF plus AMD3100/Plerixafor - mPB enhanced functionally-engrafting HSCs. These results may be of potential clinical utility. Graphical Abstract.

Chemotherapy-based versus chemotherapy-free stem cell mobilization (± plerixafor) in multiple myeloma patients: an Italian cost-effectiveness analysis

Given the availability and efficacy of the mobilizing agent plerixafor in augmenting hematopoietic progenitor cell mobilization with granulocyte colony-stimulating factor (G-CSF), there is a strong case for comparing the cost-effectiveness of mobilization with G-CSF + cyclophosphamide versus G-CSF alone. This study investigated the cost and effectiveness (i.e., successful 4 million-CD34⁺ collection) of G-CSF alone versus high-dose cyclophosphamide (4 g/m²) + G-CSF mobilization (± on-demand plerixafor) in patients with multiple myeloma (MM) eligible for autograft in Italy. A decision tree-supported cost-effectiveness analysis (CEA) model in MM patients was developed from the societal perspective. The CEA model compared G-CSF alone with cyclophosphamide 4 g/m² + G-CSF (± on-demand plerixafor) and was populated with demographic, healthcare and non-healthcare resource utilization data collected from a questionnaire administered to six Italian oncohematologists. Costs were expressed in Euro (€) 2019. The CEA model showed that G-CSF alone was strongly dominant versus cyclophosphamide + G-CSF ( ± on-demand plerixafor), with incremental savings of €1198.59 and an incremental probability of a successful 4 million-CD34⁺ apheresis (+0.052). Sensitivity analyses confirmed the robustness of the base-case results. In conclusion, chemotherapy-free mobilization (± on-demand plerixafor) is a “good value for money” option for MM patients eligible for autograft.

Cost saving, patient centered algorithm for progenitor cell mobilization for autologous hematopoietic cell transplantation

Administration of plerixafor with granulocyte-colony stimulating factor (G-CSF) mobilizes CD34+ cells much more effectively than G-CSF alone, but cost generally limits plerixafor use to patients at high risk of insufficient CD34+ cell collection based on low peripheral blood (PB) CD34+ counts following 4 days of G-CSF. We analyzed costs associated with administering plerixafor to patients with higher day 4 CD34+ cell counts to decrease apheresis days and explored the use of a fixed split dose of plerixafor instead of weight-based dosing. We analyzed 235 patients with plasma cell disorders or non-Hodgkin's lymphoma who underwent progenitor cell mobilization and autologous hematopoietic cell transplantation (AHCT) between March 2014 and December 2017. Two hundred ten (89%) received G-CSF plus Plerixafor and 25 (11%) received G-CSF alone. Overall, 180 patients (77%) collected in 1 day, 53 (22%) in 2 days and 2 (1%) in 3 days. Based on our data, we present a probabilistic algorithm to identify patients likely to require more than one day of collection using G-CSF alone. CD34+ cell yield, ANC and platelet recovery were not significantly different between fixed and standard dose plerixafor. Plerixafor enabled collection in 1 day and with estimated savings of $5000, compared to patients who did not receive plerixafor and required collection for three days. While collection and processing costs and patient populations vary among institutions, our results suggest re-evaluation of current algorithms.

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.

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors

BACKGROUND

Guidelines recommend treatment with 4-5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection.

METHODS

HLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34⁺ counts ≥0.04 × 10⁶/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34⁺ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm.

RESULTS

Of the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34⁺ cell count of 0.06 × 10⁶/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34⁺ count was significantly greater, whereas total nucleated, mononuclear and CD3⁺ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection.

DISCUSSION

Day 4 PB CD34⁺ threshold of ≥0.04 × 10⁶/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.

Mobilization and Collection of Peripheral Blood Stem Cells in Adults: Focus on Timing and Benchmarking

Peripheral blood stem cells (PBSCs) are preferentially used as a hematopoietic stem cell source for autologous blood stem cell transplantation (ABSCT) upon high-dose chemotherapy (HDT) in a variety of hemato-oncologic diseases. As a prerequisite, hematopoietic stem cells have to be mobilized into the peripheral blood (PB) and collected by leukapheresis (LP). Despite continuous improvements, e.g., the introduction of plerixafor, current challenges are the further optimization regarding the leukapheresis procedure, preventing collection failures, as well as benchmarking and harmonization of mobilization approaches between institutions.This chapter summarizes the current PBSC mobilization and collection approaches and is focusing on timely orchestration of mobilization therapy, granulocyte colony-stimulating factor (G-CSF) application, and peripheral blood (PB) CD34⁺ cell assessment. Moreover, strategies for prediction and performance assessment of the PBSC collection yield are discussed.

Peripheral blood stem cell mobilization; a look ahead

THE PURPOSE OF REVIEW

Mobilized peripheral blood is the predominant source of stem and progenitor cells for hematologic transplantation. Successful transplant requires sufficient stem cells of high enough quality to recapitulate lifelong hematopoiesis, but in some patients and normal donors, reaching critical threshold stem cell numbers are difficult to achieve. Novel strategies, particularly those offering rapid mobilization and reduced costs, remains an area of interest.This review summarizes critical scientific underpinnings in understanding the process of stem cell mobilization, with a focus on new or improved strategies for their efficient collection and engraftment.

RECENT FINDINGS

Studies are described that provide new insights into the complexity of stem cell mobilization. Agents that target new pathways such HSC egress, identify strategies to collect more potent competing HSC and new methods to optimize stem cell collection and engraftment are being evaluated.

SUMMARY

Agents and more effective strategies that directly address the current shortcomings of hematopoietic stem cell mobilization and transplantation and offer the potential to facilitate collection and expand use of mobilized stem cells have been identified.

Orchestration of Chemomobilization and G-CSF Administration for Successful Hematopoietic Stem Cell Collection

Successful collection of peripheral blood stem cells (PBSCs) depends on the optimal orchestration of mobilization chemotherapy, granulocyte colony stimulating factor (G-CSF) application, and CD34⁺ cell number assessment in the peripheral blood (PB). However, determining the optimal timing in accordance to the applied chemomobilization regimen can be challenging. Although most centers apply their own local timing schedules, a reliable timetable including the currently most often used mobilization regimens is lacking. We present a comprehensive analysis of the timing modalities for 11 of the most commonly used chemomobilization regimens. A retrospective analysis was performed on the clinical and PBSC collection parameters (including duration of G-CSF application, time point of CD34⁺ assessment, PB CD34⁺ cell count, number of leukapheresis [LP] sessions, processed blood volume, and CD34⁺ collection results) of 91 representatively selected patients who had undergone stem cell mobilization at 2 collection centers. Six to 10 patients were analyzed per regimen with a variety of diagnoses, including multiple myeloma, malignant lymphoma, and sarcoma. No collection failures (<2 × 10⁶ CD34⁺ cells/kg body weight) were observed. All analyzed patients successfully reached their individual collection goal in adherence to the given schedule of chemotherapy, application of G-CSF, measurement of CD34⁺ cells, and subsequent LP. The presented data on the timing of chemomobilization, G-CSF application, and stem cell collection may be helpful in clinical decision making and contribute to a more transparent and predictable treatment process.

Rapid Mobilization Reveals a Highly Engraftable Hematopoietic Stem Cell

Hematopoietic stem cell transplantation is a potential curative therapy for malignant and nonmalignant diseases. Improving the efficiency of stem cell collection and the quality of the cells acquired can broaden the donor pool and improve patient outcomes. We developed a rapid stem cell mobilization regimen utilizing a unique CXCR2 agonist, GROβ, and the CXCR4 antagonist AMD3100. A single injection of both agents resulted in stem cell mobilization peaking within 15 min that was equivalent in magnitude to a standard multi-day regimen of granulocyte colony-stimulating factor (G-CSF). Mechanistic studies determined that rapid mobilization results from synergistic signaling on neutrophils, resulting in enhanced MMP-9 release, and unexpectedly revealed genetic polymorphisms in MMP-9 that alter activity. This mobilization regimen results in preferential trafficking of stem cells that demonstrate a higher engraftment efficiency than those mobilized by G-CSF. Our studies suggest a potential new strategy for the rapid collection of an improved hematopoietic graft.

Plerixafor in poor mobilizers with non-Hodgkin's lymphoma: a multi-center time-motion analysis

High-dose chemotherapy alongside peripheral blood stem cell (PBSC) infusion has become the standard of care in different hematologic malignancies. The goal of PBSC mobilization is to allow collection of sufficient CD34+ cells to proceed to transplantation. The current mobilization regimen with granulocyte colony-stimulating factor (G-CSF), alone or in combination with chemotherapy, still fails in 10-25% of patients. Plerixafor is able to rescue most of these patients from mobilization failure. In this study, we investigated the impact of plerixafor on the cost and time spent on apheresis in patients who were considered poor mobilizers, with <20 × 10⁶/µl peripheral CD34+ cells after mobilization but prior to apheresis. Patient hospital records from ten centers in three European countries were reviewed and compared during two time periods, namely prior and after plerixafor introduction to the market. During the plerixafor period, patients spent less time on apheresis (350 vs. 461  min). Poor mobilizers given plerixafor collected more CD34+ cells during the first apheresis session, leading to a decrease in the average number of apheresis sessions needed. The total apheresis yield was unaffected. This analysis shows that the use of plerixafor lessens the time-effort associated with the management of poor mobilizers and reduces apheresis costs.

Single Dose Preemptive Plerixafor for Stem Cell Mobilization for ASCT After Lenalidomide Based Therapy in Multiple Myeloma: Impact in Resource Limited Setting

Peripheral blood stem cell mobilization with cytokines for autologous stem cell transplant in multiple myeloma is adversely affected by initial induction therapy consisting of either Lenalidomide or cytotoxic drugs, with failure rates of up to 45%. The use of Plerixafor with G-CSF for PBSC mobilisation significantly improves the chances of a successful mobilization. Plerixafor is a costly therapy and increases the overall costs of ASCT which can affect the number of patients being taken up for ASCT in resource limited settings. We prospectively studied the impact of single dose preemptive Plerixafor for PBSC mobilization in patients with prior Lenalidomide exposure. 26 patients who had received Lenalidomide based induction protocol underwent PBSC mobilisation during the study period with G-CSF 10 μg/kg/day SC for 4 days and single dose preemptive Plerixafor 240 μg/kg SC stat 11 h before the scheduled PB stem cell harvest on D5, based on a D4 PB CD34+ counts of <20/μL. A median of 07 cycles of Lenalidomide based combination therapy was used for induction therapy prior to ASCT. 84% patients underwent successful mobilization with one sitting of stem cell harvest post a single dose of Inj Plerixafor. 7.6% patients failed to mobilise the predefined minimum cell dose of CD34 and could not be taken up for ASCT. The median CD34% of the harvest bag sample was 0.33% (0.1-0.97%). Injection site erythema (34%), paresthesia's (34%) and nausea (30%) were the commonest adverse events reported post Inj Plerixafor. We did a real-world cost analysis for a resource limited setting for PBSC mobilization and found significant cost savings for the preemptive Plerixafor group.

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.

Hematopoietic progenitor cell mobilization for autologous transplantation - a literature review

The use of high-dose chemotherapy with autologous support of hematopoietic progenitor cells is an effective strategy to treat various hematologic neoplasms, such as non-Hodgkin lymphomas and multiple myeloma. Mobilized peripheral blood progenitor cells are the main source of support for autologous transplants, and collection of an adequate number of hematopoietic progenitor cells is a critical step in the autologous transplant procedure. Traditional strategies, based on the use of growth factors with or without chemotherapy, have limitations even when remobilizations are performed. Granulocyte colony-stimulating factor is the most widely used agent for progenitor cell mobilization. The association of plerixafor, a C-X-C Chemokine receptor type 4 (CXCR4) inhibitor, to granulocyte colony stimulating factor generates rapid mobilization of hematopoietic progenitor cells. A literature review was performed of randomized studies comparing different mobilization schemes in the treatment of multiple myeloma and lymphomas to analyze their limitations and effectiveness in hematopoietic progenitor cell mobilization for autologous transplant. This analysis showed that the addition of plerixafor to granulocyte colony stimulating factor is well tolerated and results in a greater proportion of patients with non-Hodgkin lymphomas or multiple myeloma reaching optimal CD34⁺ cell collections with a smaller number of apheresis compared the use of granulocyte colony stimulating factor alone.

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.

A plerixafor-based strategy allows adequate hematopoietic stem cell collection in poor mobilizers: results from the Canadian Special Access Program

Plerixafor effectively mobilizes hematopoietic stem cells (HSCs). However, most patients' cells are successfully collected using traditional strategies and there is limited cost-effectiveness data. The objectives of this study were to: (1) summarize the published reports of mobilization using a plerixafor-based strategy during compassionate access programs and (2) describe the Canadian experience with plerixafor during its availability by Health Canada's Special Access Program. A literature search identified reports of plerixafor-based mobilization during compassionate access programs. Overall, successful collection of at least 2 × 10(6) CD34+ cells/kg was achieved in ~75% of patients, and about two-thirds of patients went on to HSCT. A greater proportion of patients had successful collections when plerixafor was used in the upfront or preemptive settings. Plerixafor was made available by Health Canada's SAP from September 2008 to December 2010. In 96 of 132 (73%) patients, there was successful collection of at least 2 × 10(6) CD34+ cells/kg. Ninety-nine (75%) patients went on to receive an autologous transplant. Plerixafor-based mobilization is effective in perceived poor mobilizers. The optimal way to incorporate plerixafor into a mobilization strategy, however, remains to be determined. Centre-specific analysis of resource utilization may help to identify the most cost-effective way to implement various plerixafor-based mobilization strategies.