The role of diagnosis in patients failing peripheral blood progenitor cell mobilization

Baseline inflammation indexes and neutrophil-to-LDH ratio for prediction of the first mobilization failure without plerixafor-based regimens in multiple myeloma and lymphoma patients: A single-center retrospective study

BACKGROUND

Many factors were identified for mobilization failure (MF) in autologous hematopoietic stem-cell transplantation. To our knowledge, this is the first study to investigate the efficacy of baseline inflammation indexes and neutrophil-to-lactate dehydrogenase (LDH) ratio to predict MF in multiple myeloma (MM) and lymphoma.

METHODS

A total of 240 patients with lymphoma or MM hospitalized between January 2014 and June 2022 for the first stem cell mobilization were included in this retrospective single-center study. We evaluated the impact of baseline demographic, clinical, and laboratory data (before granulocyte colony-stimulating factor and chemotherapy implementation), including neutrophil, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, systemic immune-inflammation index (SII), systemic inflammatory response index (SIRI), neutrophil-to-C-reactive protein, and neutrophil-to-LDH ratios on MF.

RESULTS

A total of 240 patients were divided into successful (214 patients, 89.16%) and poor mobilizers (26 patients, 10.84%). Poor mobilizers had lower neutrophil, NLR, SII, and neutrophil-to-LDH ratios (P values were .001, .022, .001, and .001, respectively). Among these markers, only the neutrophil-to-LDH ratio was statistically low in both poor mobilizer MM and lymphoma patients. Receiving operator characteristic curve analysis was performed to evaluate neutrophil, SII, and neutrophil-to-LDH ratios for MF. Neutrophil-to-LDH ratio had the highest specificity (93.93%, for ≤9.904 cut-off) compared to the other two variables. Multivariate logistic regression analysis showed that neutrophil-to-LDH ratio ≤ 9.904 (cut-off) (odds ratio: 7.116, P = .001), neutrophil counts ≤3300/mm3 (cut-off) (odds ratio: 3.248, P = .021), and lymphoma diagnosis (odds ratio: 2.674, P = .039) were independent risks for MF.

CONCLUSION

The neutrophil-to-LDH ratio could be a novel marker in lymphoma and MM patients to predict the first MF. New studies should be conducted for the optimization of this index.

Getting blood out of a stone: Identification and management of patients with poor hematopoietic cell mobilization

Hematopoietic cell transplantation (HCT) has become a primary treatment for many cancers. Nowadays, the primary source of hematopoietic cells is by leukapheresis collection of these cells from peripheral blood, after a forced egress of hematopoietic cells from marrow into blood circulation, a process known as "mobilization". In this process, mobilizing agents disrupt binding interactions between hematopoietic cells and marrow microenvironment to facilitate collection. As the first essential step of HCT, poor mobilization, i.e. failure to obtain a desired or required number of hematopoietic cell, is one of the major factors affecting engraftment or even precluding transplantation. This review summarizes the available mobilization regimens using granulocyte-colony stimulating factor (G-CSF) and plerixafor, as well as the current understanding of the factors that are associated with poor mobilization. Strategies to mobilize patients or healthy donors who failed previous mobilization are discussed. Multiple novel agents are under investigation and some of them have shown the potential to enhance the mobilization response to G-CSF and/or plerixafor. Further investigation of the risk factors including genetic factors will offer an opportunity to better understand the molecular mechanism of mobilization and help develop new therapeutic strategies for successful mobilizations.

Low baseline platelet count predicts poor response to plerixafor in patients with multiple myeloma undergoing autologous stem cell mobilization

BACKGROUND AIMS

Baseline platelet count has been shown to be a sensitive predictor of autologous peripheral blood progenitor cell collection yield in patients with multiple myeloma mobilized with granulocyte colony-stimulating factor (G-CSF). Patients who mobilize poorly with G-CSF are often treated with plerixafor to enhance mobilization. There are no surrogate markers available to predict response to plerixafor.

METHODS

We retrospectively analyzed data from 73 patients with multiple myeloma who did not have adequate mobilization with G-CSF alone and were treated with plerixafor as a rescue agent.

RESULTS

We found that baseline platelet count directly correlated with peripheral blood CD34⁺ (PB-CD34⁺) count after plerixafor treatment (r = 0.36, P < 0.0001) and the number of PB-CD34⁺ cells collected on the first day of apheresis and inversely correlated with the number of apheresis sessions needed to collect the target number of PB-CD34⁺ cells (P = 0.0015). Baseline platelet count of 153 000/µL or less was associated with 90% specificity of predicting poor response to plerixafor with a sensitivity of 33%.

CONCLUSIONS

Baseline platelet count is a good predictor of mobilization response to plerixafor in patients with multiple myeloma.

Clinical and equipment-related factors associated with the adequate peripheral blood stem cell collection in autologous transplant at a tertiary cancer center in Kerala - A retrospective cohort study

BACKGROUND

PBSC collection using apheresis is the preferred source of hematopoietic stem cells transplantation. However, apheresis procedures fail to harvest adequate CD34 yield in 5 to 40% of patients during the first collection. Therefore, this study aimed to study both the clinical- and equipmentrelated factors influencing CD34 yield among the autologous patients and to compare the collection efficiency of two apheresis equipments(Haemonetics MCS+ and Terumo Spectra Optia).

METHODS

Retrospective analysis of 69 patients underwent PBSC collection from 2015 to 2018. Frequency, clinical- and equipment-related factors responsible for adequate CD34+ cells (≥2 x106 cells/kg) yield during the first collection was studied. Factors such as collection efficiency, percentage platelet loss and percentage hemoglobin loss were considered to compare the two apheresis system.

RESULTS

Two-third (72%) patients of the study population had adequate CD34 stem cells yield during the first collection. Factors such as exposure to lenalidomide-based pretreatment regimen, peripheral blood WBC count and CD34 count are associated with the adequate CD34 yield. Optia had a slightly better collection efficiency than MCS+ (50 and 44; p=0.37). Optia had lower product volume (237 vs 298 ml) and lesser procedure duration (277 vs 360 min), whereas the median Hb loss (3.0% and 2.3%) and mean platelet loss (49% and 34%) were higher with MCS.

CONCLUSION

This study infers that the collection efficiency of both the equipments in collecting CD34 stem cells was similar. However, during PBSC collection, procedures using Optia can be preferred to MCS+ on the patients with risk of anemia and thrombocytopenia.

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.

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.

A novel association between relaxin receptor polymorphism and hematopoietic stem cell yield after mobilization

Mobilization of hematopoietic stem cells (HSCs) from the bone marrow to the peripheral blood is a complex mechanism that involves adhesive and chemotactic interactions of HSCs as well as their bone marrow microenvironment. In addition to a number of non-genetic factors, genetic susceptibilities also contribute to the mobilization outcome. Identification of genetic factors associated with HSC yield is important to better understand the mechanism behind HSC mobilization. In the present study, we enrolled 148 Korean participants (56 healthy donors and 92 patients) undergoing HSC mobilization for allogeneic or autologous HSC transplantation. Among a total of 53 polymorphisms in 33 candidate genes, one polymorphism (rs11264422) in relaxin/insulin-like family peptide receptor 4 (RXFP4) gene was significantly associated with a higher HSC yield after mobilization in Koreans. However, in a set of 101 Europeans, no association was found between circulating CD34+ cell counts and rs11264422 genotype. Therefore, we suggest that the ethnic differences in subjects’ genetic background may be related to HSC mobilization. In conclusion, the relaxin—relaxin receptor axis may play an important role in HSC mobilization. We believe that the results of the current study could provide new insights for therapies that use relaxin and HSC populations, as well as a better understanding of HSC regulation and mobilization at the molecular level.

Optimizing mobilization strategies in difficult-to-mobilize patients: The role of plerixafor

Peripheral blood stem cell collection is currently the most widely used source for hematopoietic autologous transplantation. Several factors such as advanced age, previous chemotherapy, disease and marrow infiltration at the time of mobilization influence the efficacy of CD34(+) progenitor cell mobilization. Despite the safety and efficiency of the standard mobilization protocols (G-CSF ± chemotherapy), there is still a significant amount of mobilization failure rate (10-40%), which necessitate novel agents for effective mobilization. Plerixafor, is a novel agent, has been recently approved for mobilization of hematopoietic stem cells (HSCs). The combination of Plerixafor with G-CSF provides the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail with standard mobilization regimens. The development and optimization of practical algorithms for the use Plerixafor is crucial to make hematopoietic stem cell mobilization more efficient in a cost-effective way. This review is aimed at summarizing how to identify poor mobilizers, and define rational use of Plerixafor for planning mobilization in hard-to-mobilize patients.

Hematopoietic stem and progenitor cell harvesting: technical advances and clinical utility

Hematopoietic stem and progenitor cell (HSPC) transplantations require prior harvesting of allogeneic or autologous HSPCs. HSPCs are usually present in bone marrow (BM) during the entire life, in cord blood (CB) at birth, or in peripheral blood (PB) under particular circumstances. HSPCs were first harvested in BM and later in CB and PB, as studies showed interesting features of such grafts. All harvesting methods were in use throughout the years, except BM harvesting for HSPC autologous transplantation, which was replaced by PB harvesting. BM, CB, and PB harvesting methods have been developed, and materials and devices technically improved to increase the number of HSPCs harvested. In parallel, knowing the features of the donors or patients associated with successful numbers of HSPCs allows the adaptation of appropriate harvesting methods. Moreover, it is important to ensure the safety of donors or patients while harvesting. This review describes the methods used for harvesting based on recent studies or developments around these methods, and more particularly, the means developed to increase the numbers of HSPCs harvested in each method. It also explains briefly the influence of technical improvements in HSPC harvesting on potential changes in HSPC graft composition.

GCSF with or without chemotherapy compared to Plerixafor with GCSF as salvage mobilization regimen in patients with multiple myeloma and lymphoma: collection effectiveness and cost effectiveness analysis

INTRODUCTION

Plerixafor is a novel mobilizing agent of peripheral blood stem cells (PBSCs) in lymphoma and multiple myeloma (MM) patients whose cells mobilize poorly. Due to the substantial cost associated with its use, we aimed to compare the effectiveness and cost effectiveness of Plerixafor + GCSF (PG) versus GCSF ± Chemotherapy (GC) as salvage mobilization regimens.

METHODS

The charts of consecutive lymphoma and MM patients who had undergone at least one previous attempt of PBSCs mobilization that failed or resulted in an insufficient cell dose for transplant between 2007 and 2010 were retrospectively reviewed. Patients identified received salvage mobilization with GC (prior to 2009) or PG after Plerixafor's FDA approval. Data collected included demographics, medical histories, apheresis yields and transplant outcome. The cost effectiveness analysis was from the perspective of the Jordanian Ministry of Health. The incremental cost effectiveness ratio (ICER) was calculated by dividing the difference in cost by the difference in effectiveness for the two regimens.

RESULTS

Five patients received GC and twelve received PG. A minimum CD34+ cell dose of 2 × 10(6) cells/kg was collected from 8 patients (67%) in the PG group compared to 3 (60%) in the GC group (p=0.79). The average costs were US$8570 and US$25,700 for the GC group and the PG group, respectively. The ICER was US$244,714 per successful stem cell collection.

CONCLUSION

Salvage Plerixafor use showed a non-significant improvement in PBSCs collection with a significant increase in cost. Prospective comparative effectiveness studies are warranted to inform the optimal salvage mobilization regimen. To our knowledge, this is the first study from the Middle East to describe the effectiveness and cost effectiveness of Plerixafor.

Predictive factors for poor peripheral blood stem cell mobilization and peak CD34(+) cell count to guide pre-emptive or immediate rescue mobilization

BACKGROUND AIMS

Failure in mobilization of peripheral blood (PB) stem cells is a frequent reason for not performing hematopoietic stem cell transplantation (HSCT). Early identification of poor mobilizers could avoid repeated attempts at mobilization, with the administration of pre-emptive rescue mobilization.

METHODS

Data from the first mobilization schedule of 397 patients referred consecutively for autologous HSCT between 2000 and 2010 were collected. Poor mobilization was defined as the collection of < 2 × 10(6) CD34(+)cells/kg body weight (BW).

RESULTS

The median age was 53 years (range 4-70) and 228 (57%) were males. Diagnoses were multiple myeloma in 133 cases, non-Hodgkin's lymphoma in 114, acute myeloid leukemia or myelodysplastic syndrome in 81, Hodgkin's lymphoma in 42, solid tumors in 17 and acute lymphoblastic leukemia in 10. The mobilization regimen consisted of recombinant human granulocyte-colony-stimulating factor (G-CSF) in 346 patients (87%) and chemotherapy followed by G-CSF (C + G-CSF) in 51 (13%). Poor mobilization occurred in 105 patients (29%), without differences according to mobilization schedule. Diagnosis, previous therapy with purine analogs and three or more previous chemotherapy lines were predictive factors for poor mobilization. A CD34(+)cell count in PB > 13.8/μL was enough to ensure ≥ 2 × 10(6) CD34(+)cells/kg, with high sensitivity (90%) and specificity (91%).

CONCLUSIONS

The prevalence of poor mobilization was high, being associated with disease type, therapy with purine analogs and multiple chemotherapy regimens. The threshold of CD34(+) cell count in PB identified poor mobilizers, in whom the administration of immediate or pre-emptive plerixafor could be useful to avoid a second mobilization.

Mobilisation strategies for normal and malignant cells

This review evaluates the latest information on the mobilisation of haemopoietic stem cells for transplantation, with the focus on what is the current best practice and how new understanding of the bone marrow stem cell niche provides new insights into optimising mobilisation regimens. The review then looks at the mobilisation of mesenchymal stromal cells, immune cells as well as malignant cells and what clinical implications there are.

Hematopoietic recovery kinetics predicts for poor CD34+ cell mobilization after cyclophosphamide chemotherapy in multiple myeloma

Autologous stem cell transplantation is an important part of therapy in patients with multiple myeloma. Some patients fail to collect the desired number of stem cells while others require multiple apheresis to reach the desired apheresis target. The aim of this study was to determine the predictive factors and if the hematopoietic kinetics of recovery were predictive for outcome of stem cell mobilization in cyclophosphamide + growth factor (CY-GF) mobilized patients. Three hundred and ninety six consecutive CY-GF mobilization attempts between January 2000 and December 2009 at Mayo Clinic, Rochester, MN were analyzed. Patients were divided into three groups: optimal (>5 × 10(6) CD34/kg), suboptimal (2-5 × 10(6) CD34/kg) and poor (<2 × 10(6) /kg CD34+ cells) mobilization groups. About 86% of patients had optimal stem cell collection, whereas 8% had suboptimal collection and 6% had poor (or failed) collections. Age, Hb, WBC, and platelet levels had an impact on mobilization results. Time to peripheral blood (PB) CD34+cells >10/μL predicted for efficiency of collection and the interval between recovery of WBC>1 post-CY to PB CD34+ cells>10 was shorter in the optimal collection groups. These findings suggest that for patients with a PB CD34+ cell count below 10/μL on Day 13 following CY or 1 day after the WBC>1 × 10(9) /L, addition of plerixafor may be helpful to salvage the mobilization attempt.

How I treat patients who mobilize hematopoietic stem cells poorly

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

Plerixafor with and without chemotherapy in poor mobilizers: results from the German compassionate use program

The CXCR4-inhibitor plerixafor mobilizes hematopoietic stem cells amplifying the effects of granulocyte-CSF (G-CSF). Before approval plerixafor was used in a compassionate use program (CUP) for patients who failed a previous mobilization. In the German CUP 60 patients from 23 centers (median age 56.5 years (2-75)) were given 240 μg/kg plerixafor SC 9-11 h before apheresis. A total of 78.3% (47/60) received G-CSF for 4 days before plerixafor administration; 76.6% of those (36/47) yielded at least 2.0 × 10(6) CD34(+) cells/μL. The median cell yield was 3.35 × 10(6) CD34+ cells/kg (0-29.53). Nine patients received plerixafor alone or with G-CSF for less than 4 days mobilizing a median of 3.30 × 10(6) CD34+ cells/kg (1.6-5.6). There was no significant difference between G-CSF application for 4 days and for a shorter period of time (P=0.157). A total of 47 patients received plerixafor plus G-CSF combined with chemotherapy yielding a median of 3.28 × 10(6) CD34+ cells/kg (0-24.79). In all, 40 of 60 patients (66.7%) proceeded to transplantation, and achieved a timely and stable engraftment. Side effects were rare and manageable. In conclusion, mobilization with plerixafor in poor mobilizers is safe and results in a sufficient stem cell harvest in the majority of patients.

Factors affecting autologous peripheral blood hematopoietic stem cell collections by large-volume leukapheresis: a single center experience

OBJECTIVE

To evaluate factors affecting peripheral blood hematopoietic stem cell yield in patients undergoing large-volume leukapheresis for autologous peripheral blood stem cell collection.

METHODS

Data from 304 consecutive autologous peripheral blood stem cell donors mobilized with hematopoietic growth factor (usually G-CSF), associated or not with chemotherapy, at Hospital Israelita Albert Einstein between February 1999 and June 2010 were retrospectively analyzed. The objective was to obtain at least 2 × 106 CD34+ cells/kg of body weight. Pre-mobilization factors analyzed included patient's age, gender and diagnosis. Post mobilization parameters evaluated were pre-apheresis peripheral white blood cell count, immature circulating cell count, mononuclear cell count, peripheral blood CD34+ cell count, platelet count, and hemoglobin level. The effect of pre and post-mobilization factors on hematopoietic stem cell collection yield was investigated using logistic regression analysis (univariate and multivariate approaches).

RESULTS

Pre-mobilization factors correlating to poor CD34 + cell yield in univariate analysis were acute myeloid leukemia (p = 0.017) and other hematological diseases (p = 0.023). Significant post-mobilization factors included peripheral blood immature circulating cells (p = 0.001), granulocytes (p = 0.002), hemoglobin level (p = 0.016), and CD34+ cell concentration (p < 0.001) in the first harvesting day. However, according to multivariate analysis, peripheral blood CD34+ cell content (p < 0.001) was the only independent factor that significantly correlated to poor hematopoietic stem cell yield.

CONCLUSION

In this study, peripheral blood CD34+ cell concentration was the only factor significantly correlated to yield in patients submitted to for autologous collection.

Proposed definition of 'poor mobilizer' in lymphoma and multiple myeloma: an analytic hierarchy process by ad hoc working group Gruppo ItalianoTrapianto di Midollo Osseo

Many lymphoma and myeloma patients fail to undergo ASCT owing to poor mobilization. Identification of poor mobilizers (PMs) would provide a tool for early intervention with new mobilization agents. The Gruppo italianoTrapianto di Midollo Osseo working group proposed a definition of PMs applicable to clinical trials and clinical practice. The analytic hierarchy process, a method for group decision making, was used in setting prioritized criteria. Lymphoma or myeloma patients were defined as ‘proven PM' when: (1) after adequate mobilization (G-CSF 10 μg/kg if used alone or ⩾5 μg/kg after chemotherapy) circulating CD34⁺ cell peak is <20/μL up to 6 days after mobilization with G-CSF or up to 20 days after chemotherapy and G-CSF or (2) they yielded <2.0 × 10⁶ CD34⁺ cells per kg in ⩽3 apheresis. Patients were defined as predicted PMs if: (1) they failed a previous collection attempt (not otherwise specified); (2) they previously received extensive radiotherapy or full courses of therapy affecting SC mobilization; and (3) they met two of the following criteria: advanced disease (⩾2 lines of chemotherapy), refractory disease, extensive BM involvement or cellularity <30% at the time of mobilization; age ⩾65 years. This definition of proven and predicted PMs should be validated in clinical trials and common clinical practice.

Advances in mobilization for the optimization of autologous stem cell transplantation

In autologous stem cell transplantation, mobilized peripheral blood has replaced the bone marrow as the preferred source of hematopoietic stem cells (HSCs). Because HSCs normally exist in the blood in very low numbers, the use of agents to "mobilize" HSCs from the marrow niche to the peripheral blood is essential for successful transplantation. Until recently, granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor were the only approved agents by the US Food and Drug Administration for use as peripheral blood stem cell (PBSC)-mobilizing agents in the United States, but G-CSF has become the gold standard. Unfortunately, some patients fail to mobilize sufficient numbers of PBSCs for transplantation in response to G-CSF with or without chemotherapy. Recently, a new agent, plerixafor (AMD3100) added to G-CSF has been approved to enhance PBSC mobilization. This review will discuss the current methodologies to improve hematopoietic stem cell mobilization.

Management of poor peripheral blood stem cell mobilization: incidence, predictive factors, alternative strategies and outcome. A retrospective analysis on 2177 patients from three major Italian institutions

CD34+ peripheral blood hematopoietic stem cells (HSC) are usually collected following mobilization therapy accomplished by using growth factors (GF) such as rHuG-CSF or rHuGM-CSF with or without chemotherapy. A target dose of yielded CD34+ is usually prescribed by the attending physician depending on different protocols, which may include single or double transplantation. HSC collection usually is performed when at least 20 CD34+ HSC/microL are detected by means of flow cytometry. A cumulative dose of at least 2 x 10(6)/Kg/bw CD34+ HSC has been considered as the threshold to allow a prompt and persistent hematopoietic recovery. Unfortunately, this goal is not achieved by the totality of patients undergoing mobilization regimen. In fact, 5-46% of patients who underwent mobilization therapy fail HSC collection due to very low peripheral blood HSC CD34+ count. Patients' characteristics, including age, sex, stage of the underlying disease (complete or partial remission), diagnosis, previously administered radio/chemotherapy regimens, time-lapse from last chemotherapy before mobilization and mobilization schedule (including dose of GF) were considered as possibly predictive of poor or failed mobilization. We performed a retrospective analysis in 2177 patients from three large Italian academic institutions to assess the incidence of poor mobilizers within our patients' series. Therefore, a patient who fails a first mobilization (and when an HLA-compatible related on unrelated donor is not available) could undergo a second attempt either with different mobilization schedule or by using different GF, such as stem cell factor, growth hormone (GH), or more recently newly introduced drugs such as AMD3100, alone or in combination with rHuG- or -rHuGM-CSF. Thus, we investigated the fate of those who failed a first mobilization and subsequently underwent a second attempt or alternative therapeutic approaches.

Poor hematopoietic stem cell mobilizers: a single institution study of incidence and risk factors in patients with recurrent or relapsed lymphoma

The purpose of this retrospective study was to determine the incidence and predictive factors if any, of mobilization failure in lymphoma patients referred for autologous stem cell transplantation. A total of 588 lymphoma patients were referred for transplant consultation from January 2003 to December 2004. Predictors of mobilization failure were evaluated using logistic regression analysis including diagnosis, mobilization regimen, age, sex, type and number of prior chemotherapies, bone marrow cellularity, platelet count, white count, prior bone marrow involvement with malignancy, and prior radiation therapy. Two hundred and six patients were eligible for transplantation and underwent stem cell mobilization. Twenty-nine (14%) patients failed to mobilize adequate stem cells after the first attempt. For the entire group age (>or=60 versus <60 years), diagnosis (Hodgkin's versus non-Hodgkin's lymphoma), use of cytokines alone, platelet count <150 x 10(9)/L, and bone marrow cellularity <30% were significant predictors for mobilization failure on univariate analysis. In view of small number of patients multivariate analysis was not possible. However, a low platelet count (150 x 10(9)/L) was the only significant predictor when the analysis was restricted to non-Hodgkin's lymphoma patients who were mobilized with chemotherapy. Mobilization failure rates are higher in patients with non-Hodgkin's lymphoma compared with those with Hodgkin's lymphoma. In the subset of patients who undergo chemomobilization for non-Hodgkin's lymphoma platelet count at the time of mobilization is a predictor of mobilization failure.

Peripheral blood stem cell mobilization: new regimens, new cells, where do we stand

PURPOSE OF REVIEW

Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells are widely used to reconstitute hematopoiesis; however, preclinical and clinical studies show that improvements to this mobilization can be achieved. We discuss the development of new mobilizing regimens and evaluation of new findings on mobilized stem cell populations that may improve the utility and convenience of peripheral blood stem cell transplant.

RECENT FINDINGS

Chemokines and their receptors regulate leukocyte trafficking, and altering chemokine signaling pathways mobilizes stem cells. In recent trials, combination use of the chemokine (C-X-C motif) receptor 4 antagonist AMD3100 and granulocyte colony-stimulating factor mobilized more CD34 cells in fewer days than granulocyte colony-stimulating factor alone and allowed more patients to proceed to autotransplant. In preclinical studies the chemokine GRObeta synergizes with granulocyte colony-stimulating factor and when used alone or with granulocyte colony-stimulating factor mobilizes more primitive hematopoietic stem cells with less apoptosis, higher integrin activation, lower CD26 expression and enhanced marrow homing compared with granulocyte colony-stimulating factor. Hematopoietic stem cells mobilized by GRObeta or AMD3100 demonstrate superior engraftment and contribution to chimerism in primary and secondary transplant studies in mice, and peripheral blood stem cells mobilized by AMD3100 and granulocyte colony-stimulating factor in patients demonstrate enhanced engraftment capabilities in immunodeficient mice.

SUMMARY

Alternate regimens differentially mobilize stem cell populations with unique intrinsic properties with the potential to expand the utility of hematopoietic transplantation. Continued mechanistic evaluation will be critical to our understanding of mechanisms of mobilization and their use in regenerative medicine.

Platelet count is a sensitive predictor of autologous peripheral blood progenitor cell collection yield in previously treated plasma cell disease patients

BACKGROUND

It is often a clinical dilemma to determine when to collect autologous peripheral blood progenitor cells (PBPCs) in patients who received prior chemotherapy. It is also challenging to predict if the collected cells will be enough for one or two transplants.

STUDY DESIGN AND METHODS

A total of 103 PBPC donors were followed to evaluate factors that predict poor autologous PBPC collection. The donors were categorized into three groups: plasma cell disorders (PCDs), lymphomas, and normal allogeneic donors.

RESULTS

Our evaluation showed that platelet (PLT) count before growth factor administration significantly correlated with total CD34+ cell yield (Spearman r = 0.38, p < 0.001). Further analysis showed this correlation was only significant in plasma cell disease patients who received prior chemotherapy (Spearman r = 0.5, p = 0.008). Baseline PLT counts did not correlate with PBPC collection yield in untreated PCD, lymphoma, and normal allogeneic donors. In addition, daily PLT count during PBPC harvest correlated with CD34+ cell yield for that day (Spearman r = 0.41, p < 0.001). With a multiple linear regression model (adjusted R(2) = 0.31, AIC = 63.1), it has been determined that the baseline PLT count significantly correlates with total CD34+ cell yield in treated PCD patients.

CONCLUSION

Baseline PLT count is a sensitive indicator of autologous PBPC mobilization in PCD patients who received prior chemotherapy. This finding may be considered before growth factor administration to determine the optimal period to mobilize treated PCD patients and to predict if enough cells can be collected for one or two transplants.

Improving the Oral Efficacy of Recombinant Granulocyte Colony-Stimulating Factor and Transferrin Fusion Protein by Spacer Optimization

PURPOSE

To improve the oral efficacy of the recombinant fusion protein containing granulocyte colony-stimulating factor (G-CSF) and transferrin (Tf) by inserting a linker between the two protein domains.

MATERIALS AND METHODS

Oligonucleotides encoding flexible and helix-forming peptides were inserted to the recombinant plasmids. The fusion protein without linker insertion was used for comparison. The G-CSF cell-proliferation and Tf receptor-binding activities of the fusion proteins were tested in NFS-60 cells and Caco-2 cells, respectively, and in vivo myelopoietic assay with both subcutaneous and oral administration was performed in BDF1 mice.

RESULTS

All fusion proteins produced from transfected HEK293 cells were positive in Western-blotting assay with anti-G-CSF and anti-Tf antibodies. Among them, the fusion protein with a long helical (H4-2) linker showed the highest activity in NFS-60 cell proliferation assay, with an EC50 about ten-fold lower than that of the non-linker fusion protein. The fusion protein with H4-2 linker also showed a significantly higher myelopoietic effect when administered either subcutaneously or orally in BDF1 mice.

CONCLUSION

The insertion of a linker peptide, such as the helix linker H4-2, between G-CSF and Tf domains in the recombinant fusion protein can improve significantly both in vitro and in vivo myelopoietic activity over the non-linker fusion protein.

Pegfilgrastim effectively mobilizes PBSC in a poor mobilizer multiple myeloma patient

Studies performed on mice and healthy human volunteers have shown that a single dose of pegfilgrastim (Peg-GCSF) is effective in stimulating peripheral blood stem cells (PBSC) mobilization. This prompted us to try the stimulation with pegfilgrastim in a patient previously non-mobilizing with a combination of chemotherapy and filgrastim. In December 2003, a 65-yr-old man was diagnosed as having stage III A IgG/k multiple myeloma. He received three courses of polichemotherapy (DC-IE) obtaining a stable response. Afterwards, the patient was treated with high-dose cyclophosphamide (CPM; 7 g/sqm) plus daily 10 mcg/kg filgrastim in order to mobilize PBSC, without success. After 2 months off therapy, the disease progressed and the patient received alternate cycles VAD (vincristine, dexamethasone, adriblastine)/high-dose dexamethasone. A second attempt to mobilize PBSC, using daily 10 mcg/kg filgrastim after the second and third VAD cycle, failed. In a further attempt to mobilize PBSC, we administered a single dose of 12 mg pegfilgrastim on day 5 after a fourth VAD course. Daily evaluation of circulatory CD34+ cells was started from day 8 after the end of chemotherapy. On day +10 postchemotherapy the CD34+ cell count was 24/microL and two aphaeresis were performed, harvesting 1.6 x 10(6) and 0.89 x 10(6) CD34+ cells/kg respectively (total 2.49 x 10(6) cells/kg). The only side effect was moderate skeletal pain. The patient underwent successful transplantation. The median times necessary to recover 0.5 x 10(9) PMN/L and 20 x 10(9) platelets/L after PBSC reinfusion were 9 and 12 d respectively. The patient did not need red blood cell or platelet transfusions. He experienced a sustained engraftment and maintains complete remission 9 months after the reinfusion. In conclusion, a single dose of pegfilgrastim was able to mobilize a sufficient number of CD34+ in a multiple myeloma patient not responsive to two previous attempts with high or standard dose chemotherapy followed by filgrastim. This approach, if confirmed on larger series and other diseases, could open new opportunities in stem cell mobilization for poor or non-mobilizers.

Prospective randomized comparative observation of single- vs split-dose lenograstim to mobilize peripheral blood progenitor cells following chemotherapy in patients with multiple myeloma or non-Hodgkin’s lymphoma

In patients with hematologic malignancies, granulocyte colony-stimulating factor (G-CSF) following chemotherapy is widely used to mobilize peripheral blood progenitor cells (PBPCs), but there have been no trials comparing schedules of G-CSF following chemotherapy. We conducted a prospective randomized comparative observation of the mobilization with a single dose (10 microg kg once a day) or split dose (5 microg kg twice a day) of lenograstim following chemotherapy in 25 multiple myeloma (MM) and 15 non-Hodgkin's lymphoma (NHL) patients. Chemotherapy was cyclophosphamide 4 g/m2 for MM and ESHAP with or without Rituximab for NHL. The median number of harvested CD34+ cells was 19.4 x 10(6)/kg and 15.8 x 10(6)/kg in the single- and split-dose groups, respectively (p=0.47). Targeted collection of 5 x 10(6) CD34+ cells/kg was achieved in 18/20 patients in the single-dose group and in all 20 patients of the split-dose group (p=0.24), with the median number of sessions 1 and 2 in the single- and split-dose groups, respectively (p=0.13). We could not observe statistically significant differences between a single-dose and split-dose lenograstim following chemotherapy in enhancing the mobilization of PBPCs in MM or NHL patients.