Defining a therapeutic dose of peripheral blood stem cells

Autologous peripheral blood stem cell harvest timing by absolute neutrophil count in children and young adult patients: Single-institute experience

BACKGROUND

Myeloablative, high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT) improves outcome in some high-risk malignant solid tumors and lymphomas in children and young adults.

METHODS

We performed 16 peripheral blood stem cell (PBSC) harvests in 12 children and 2 young adult patients with a high-risk malignant solid tumor or refractory/relapsed Hodgkin's lymphoma from August 2015 to December 2020. In our chemotherapy mobilization protocol, we used an absolute neutrophil count (ANC) of >1 × 109/L following the nadir after chemotherapy as the criterion for undertaking the apheresis.

RESULTS

The median CD34+ cell count per kg body weight of the 33 apheresis products was 4.92 × 106 cells/kg (range, 0.34-22.53 × 106 cells/kg). Thirteen of the 14 patients (93%) had successful PBSC collections that met their goals for PBSCT. Three patients did not receive PBSCT due to disease progression prior to transplantation. Prompt engraftment occurred in all the remaining 11 patients with 17 PBSCTs.

CONCLUSION

Our data suggest that ANC can be helpful as a surrogate parameter in clinical decision-making when the peripheral blood CD34+ count is unavailable.

Comparison of peripheral blood automated hematopoietic progenitor cell count and flow cytometric CD34+ cell count

BACKGROUND

Stem cell apheresis in the context of autologous stem cell transplantation requires an accurate cluster of differentiantion 34 (CD34+) count determined by flow cytometry as the current gold standard. Since flow cytometry is a personnel and time-intensive diagnostic tool, automated stem cell enumeration may provide a promising alternative. Hence, this study aimed to compare automated hematopoietic progenitor enumeration carried out on a Sysmex XN-20 module compared with conventional flow cytometric measurements.

METHODS

One hundred forty-three blood samples from 41 patients were included in this study. Correlation between the two methods was calculated over all samples, depending on leukocyte count and diagnosis.

RESULTS

Overall, we found a high degree of correlation (r = 0.884). Furthermore, correlation was not impaired by elevated leukocyte counts (>10 000/μL, r = 0.860 vs <10 000/μL, r = 0.849; >20 000/μL, r = 0.843 vs <20 000/μL, r = 0.875). However, correlation was significantly impaired in patients with multiple myeloma (multiple myeloma r = 0.840 vs nonmyeloma r = 0.934).

SUMMARY

Stem cell measurement carried out on the Sysmex XN-20 module provides a significant correlation with flow cytometry and might be implemented in clinical practice. In clinical decision-making, there was discrepancy of under 15% of cases. In multiple myeloma patients, XN-20 should be used with caution.

Use of subgroup-specific hematopoietic stem cell collection efficiencies to improve truncation calculations for large-volume leukapheresis procedures

PURPOSE

A critical component of optimizing peripheral blood (PB) hematopoietic stem cell (HSC) collections is accurately determining the processed blood volume required to collect the targeted number of HSCs. Fundamental to most truncation equations employed to determine this volume is the procedure's estimated collection efficiency (CE), which is typically applied uniformly across all HSC collections. Few studies have explored the utility of using different CEs in subpopulations of donors that have substantially different CEs than the institutional average.

METHODS

Initial procedures from 343 autologous and 179 allogeneic HSC collections performed from 2018 to 2021 were retrospectively analyzed. Predictive equations were developed to determine theoretical truncation rates in various donor subgroups.

RESULTS

Quantitative variables (pre-procedure cell counts) and qualitative variables (relatedness to recipient, gender, method of venous access, and mobilization strategy) were found to significantly impact CE. However, much of the variability in CE between donors could not be explained by the variables assessed. Analyses of procedures with high pre-collection PB cell counts identified lower CE values for these donors' truncation equations which still allow truncation but minimize risk of collecting less CD34+ cells than requested.

CONCLUSIONS

Individualized CE does not substantially improve truncation volume calculations over use of a fixed CE and adds complexity to these calculations. The optimal fixed CE varies between autologous and allogeneic donors, and donors with high pre-collection PB cell counts in either of these groups. This model will be clinically validated and continuously refined through analysis of future HSC collections.

Primed for change: The effect of a blood prime on peripheral blood stem cell collection and accuracy of a prediction tool in pediatric patients

Pediatric apheresis collection of peripheral blood stem cells for autologous transplantation often requires use of a blood prime. We evaluated the relationship between pre-apheresis blood CD34+ counts and final CD34+ yield with use of a blood prime. Forty patients underwent apheresis stem cell collection in a 5 year period in our hospital, of which 27 required blood priming of the apheresis machine. Despite the blood prime group having significantly higher pre-apheresis CD34+ cell counts, this group processed a relatively higher volume of blood due to a higher dilutional effect and collected significantly less than predicted CD34+ cell yield. Use of weight-specific collection efficiencies and dilution-adjusted pre-apheresis CD34+ counts will help in accurately estimating the whole blood volume to process for PBSC collection and therefore increase efficiency and decrease the overall cost of collection.

Fifty years of BMT: risk stratification, donor matching, and stem cell collection for transplantation

In this review, we discuss recipient risk assessment for allo-HCT regarding comorbidities present at baseline to predict non relapse mortality. We further reviewed the incorporation of remission status and cytogenetic risk prior to allograft transplantation to predict relapse rates for hematologic malignancies. HCT-CI and DRI are tools available to physicians to assess the risk-benefit of allo-HCT in patients referred for transplantation. Next, we discuss our algorithm for donor selection and criteria for donor selection in case matched donors are not available. Finally, we discuss our approach for stem cell mobilization, especially in donors failing G-CSF, and our approach for the use of plerixafor and data supporting its use.

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown. We wanted to analyze the relationship between CD34+ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs. A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008 to 2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34+ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM. One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×106/kg CD34+ cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 106/kg. Relapse rates were lower in patients receiving >3.6 × 106/kg CD34+ cells (p = .05). Higher CD34+ doses were not associated with increased NRM (p = .59). Stratification of CD34+ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p = .66), OS (p = .29), risk of relapse (p = .57), or EIC (p = .87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4 × 108/kg did not experience superior PFS (p = .26), superior OS (p = .14), reduced risk of relapse (p = .37), or reduced NRM (p = .25). Children with medulloblastoma had superior PFS (p < .001), OS (p = .01), and relapse rates (p = .001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days versus 12 days in the highest and lowest infused CD34+ quartiles, respectively. For children undergoing autologous HSCT for CNSTs, increasing CD34+ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Human Hematopoietic Stem Cells Co-cultured in 3D with Stromal Support to Optimize Lentiviral Vector-mediated Gene Transduction

HSC transplantation (HSCT) has emerged as a promising treatment option for hematological and immunological disorders. Unfortunately, many viral vectors are inefficient at transduction, limiting the number of cells available for gene therapy in cord blood HSC transplantation. Combining ex vivo expansion and genetic manipulation of cord blood cells is a potential gene therapy approach. We present a 3D co-culture method using a demineralized bone matrix scaffold to optimize lentiviral vector-mediated gene transduction. pLenti-III-miR-GFP-has-miR-124 was transduced into cord blood HSCs. Transduced CD34 + cells co-cultured on the stromal layer for 72 h under cytokine-free conditions. We performed flow cytometry, colony assays, real-time polymerase chain reaction, and SEM morphological analysis. Seventy-two hours after transduction, when pLentiIII-miR-GFP-has-miR-124 and control vector-transduced expanded cord blood HSCs were compared to non-transduced expanded cord blood HSCs, the findings revealed 15 ± 3.04 and 55 ± 3.05-fold increases in miR-124 mRNA expression, respectively. Compared to a control culture on the same day, the expansion of CD34+, CD38-HSCs in 3D culture increased 544 ± 31.09 fold. This result demonstrated that the 3D-culture system could emerge as a novel approach to overcoming the current limitations of cord blood HSC transduction. In the future, this research could be applied in a therapeutic setting.

Determination of the relationship between CD34+ stem cell amount and DMSO in hematopoetic stem cell transplantation

It is important to calculate the CD34+ stem cell (SC) count at the right time in patients with hematological malignancies who will undergo Hematopoietic Stem Cell Transplantation (HSCT). The amount of SC infused into the patient affects the engraftment time and healing process of the patient. In this study, we aimed to compare which of the DMSO-not removed and DMSO-removed samples showed the CD34 + SC amount more accurately as the SC amount determination method after the SC was dissolved after cryopreservation in patients who will undergo HSCT. A total of 22 patients were included in the study. All 22 patients were transplanted from frozen samples using DMSO. After the SC products were dissolved in a 37 °C water bath, they were washed 2 times and the amount of CD34+ SC was studied from the samples taken by removing DMSO and without removing DMSO. In the findings, the amounts of CD34+ SC studied with both methods were compared. The increase in the number and percentage of CD34+ SC after DMSO-removed was found to be statistically significant both in terms of difference and proportionally, and the calculated effect sizes also showed that the increase was clinically significant (Cohen's d is between 0.43 and 0.677). After thawing the frozen SCs of the patients who will undergo HSCT, the analysis of CD34+ SCs from which DMSO is removed provides a more accurate calculation of the CD34+ SC amount in the AP.

The Effect of the COVID-19 Pandemic on Unrelated Allogeneic Hematopoietic Donor Collections and Safety

BACKGROUND AND OBJECTIVES

The COVID-19 pandemic profoundly influenced unrelated donor (UD) allogeneic peripheral blood stem cell (PBSC) collections. Changes included efforts to minimize COVID-19 exposure to donors and cryopreservation of products. The extent to which the efficacy and safety of PBSC donations were affected by the pandemic is unknown.

METHODS

Prospective cohort analysis of PBSC collections comparing pre-pandemic (01 April 2019-14 March 2020) and pandemic (15 March 2020-31 March 2022) eras.

RESULTS

Of a total of 291 PBSC collections, cryopreservation was undertaken in 71.4% of pandemic donations compared to 1.1% pre-pandemic. The mean requested CD34⁺ cell dose/kg increased from 4.9 ± 0.2 × 10⁶ pre-pandemic to 5.4 ± 0.1 × 10⁶ during the pandemic. Despite this increased demand, the proportion of collections that met or exceeded the requested cell dose did not change, and the mean CD34⁺ cell doses collected (8.9 ± 0.5 × 10⁶ pre-pandemic vs. 9.7 ± 0.4 × 10⁶ during the pandemic) remained above requested targets. Central-line placements were more frequent, and severe adverse events in donors increased during the pandemic.

CONCLUSION

Cryopreservation of UD PBSC products increased during the pandemic. In association with this, requested cell doses for PBSC collections increased. Collection targets were met or exceeded at the same frequency, signaling high donor and collection center commitment. This was at the expense of increased donor or product-related severe adverse events. We highlight the need for heightened vigilance about donor safety as demands on donors have increased since the pandemic.

The density of bone marrow mononuclear cells and CD34+ cells in patients with three neurologic conditions

BACKGROUND

This study aimed to identify the density of mononuclear cells (MNCs) and CD34+ cells in the bone marrow of patients with three neurologic conditions.

METHODS

The study included 88 patients with three neurologic conditions: 40 with cerebral palsy (CP) due to oxygen deprivation (OD), 23 with CP related to neonatal icterus (NI), and 25 with neurological sequelae after traumatic brain injury. Bone marrow aspiration was conducted from the patients' bilateral anterior iliac crest under general anesthesia in an operating theater. MNCs were isolated by Ficoll gradient centrifugation and then infused intrathecally.

RESULTS

There was a significant difference in the average MNC per ml and percentage of CD34+ cells by the type of disease, age group, and infusion time (p value < 0.05). The multivariable regression model showed the percentage of CD34+ association with the outcome (gross motor function 88 items- GMFM-88) in patients with CP.

CONCLUSIONS

The density of MNCs was 5.22 million cells per mL and 5.03% CD34+ cells in patients with three neurologic conditions. The highest density of MNCs in each ml of bone marrow was found in patients with CP due to OD, whereas the percentage of CD34+ cells was the highest among patients with CP related to NI.

A systems pharmacology model for gene therapy in sickle cell disease

We developed a mathematical model for autologous stem cell therapy to cure sickle cell disease (SCD). Experimental therapies using this approach seek to engraft stem cells containing a curative gene. These stem cells are expected to produce a lifelong supply of red blood cells (RBCs) containing an anti‐sickling hemoglobin. This complex, multistep treatment is expensive, and there is limited patient data available from early clinical trials. Our objective was to quantify the impact of treatment parameters, such as initial stem cell dose, efficiency of lentiviral transduction, and degree of bone marrow preconditioning on engraftment efficiency, peripheral RBC numbers, and anti‐sickling hemoglobin levels over time. We used ordinary differential equations to model RBC production from progenitor cells in the bone marrow, and hemoglobin assembly from its constituent globin monomers. The model recapitulates observed RBC and hemoglobin levels in healthy and SCD phenotypes. Treatment simulations predict dynamics of stem cell engraftment and RBC containing the therapeutic gene product. Post‐treatment dynamics show an early phase of reconstitution due to short lived stem cells, followed by a sustained RBC production from stable engraftment of long‐term stem cells. This biphasic behavior was previously reported in the literature. Sensitivity analysis of the model quantified relationships between treatment parameters and efficacy. The initial dose of transduced stem cells, and the intensity of myeloablative bone marrow preconditioning are predicted to most positively impact long‐term outcomes. The quantitative systems pharmacology approach used here demonstrates the value of model‐assisted therapeutic design for gene therapies in SCD.

Race/ethnicity and underlying disease influences hematopoietic stem/progenitor cell mobilization response: A single center experience

BACKGROUND

Whether race/ethnicity plays a role in hematopoietic stem/progenitor cells (HSPC) mobilization in autologous donors has not been studied. We hypothesize that donor characteristic including race/ethnicity, age, sex, body mass index, and diagnostic groups influences HSPC mobilization. Diagnostic groups include healthy allogeneic donors, autologous multiple myeloma (MM) and non-MM donors.

STUDY DESIGN AND METHODS

Here, we conducted a single-center retrospective study in 64 autologous patients and 48 allogeneic donors. Autologous donors were patients diagnosed with MM or non-MM. All donors were grouped as African American (AA), White (W), or "Other"(O).

RESULTS

Multivariate analysis demonstrated diagnostic group differences for CD34+ cell yields between race/ethnicity. Specifically, non-MM patients had the lowest CD34+ cell yields in AA and O, but not in W. For pre-apheresis peripheral blood (PB) CD34+ cell numbers, race/ethnicity had a significant effect both in bivariate and multivariate analyses. Non-MM patients had the lowest, and AA patients had the highest PB CD34+ cells. The results support the view that past therapies used in MM are likely more conducive of recovery of HSPC.

CONCLUSIONS

Our study shows that race/ethnicity and diagnostic group differences influenced CD34+ cell mobilization response across donor types. Interestingly, autologous MM donors with the aid of plerixafor displayed comparable CD34 yields to allogeneic donors. Even though both MM and non-MM donors received plerixafor, non-MM donors had significantly lower CD34 yields among AA and O donors but not in W donors. Larger studies would be required to validate the role of diagnostic groups and race/ethnicity interactions.

Repurposing of glycine transport inhibitors for the treatment of erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is a rare disease in which patients experience severe light sensitivity. It is caused by a deficiency of ferrochelatase (FECH), the last enzyme in heme biosynthesis (HBS). The lack of FECH causes accumulation of its photoreactive substrate protoporphyrin IX (PPIX) in patients' erythrocytes. Here, we explored an approach for the treatment of EPP by decreasing PPIX synthesis using small-molecule inhibitors directed to factors in the HBS pathway. We generated a FECH-knockout clone from K562 erythroleukemia cells, which accumulates PPIX and undergoes oxidative stress upon light exposure. We used these matched cell lines to screen a set of publicly available inhibitors of factors in the HBS pathway. Inhibitors of the glycine transporters GlyT1 and GlyT2 lowered levels of PPIX and markers of oxidative stress selectively in K562^11B4 cells, and in primary erythroid cultures from an EPP patient. Our findings open the door to investigation of glycine transport inhibitors for HBS disorders.

Optimizing pediatric peripheral blood stem cell collection

INTRODUCTION

Pediatric PBSC harvests pose specific challenges during apheresis and a knowledge of the same and variables affecting PBSC collection are very important in planning these procedures. In the present study safety profile of pediatric PBSC procedures and variables influencing the successful collection were analyzed.

METHOD

Pediatric PBSC harvest data for 3 years was reviewed for donor, procedural and product parameters and any specific challenges faced during the procedures. Successful PBSC collection was defined when CD34 dose obtained was ≥2 × 10⁶ cells/Kg of recipients' body weight.

RESULTS

85 PBSC collections performed on 46 children (age range 1.5-15 years) were included. Sixty-two procedures were on autologous donors and 23 on allogenic donors. The median CD34+ cell dose in the PBSC product per procedure was 2.12 × 10⁶ cells/Kg for autologous procedures and 4.6 × 10⁶ cells/Kg for allogenic procedures. Systemic adverse reaction was observed during only one procedure (0.01 %) and was managed conservatively. Successful dose was collected in 52 procedures (61.17 %) and was significantly associated with CD34+ count of more than 19.7/μL, monocyte count of more than 1.65 × 10⁶/μL, allogenic collection and female gender (p = 0.00001, p = 0.011, p = 0.00052, and p = 0.0001, respectively).

CONCLUSION

PBSC collection is safe in pediatric age groups and pre-procedure CD34 count of ≥20/μL on the day of collection may result in successful collection of stem cell dose. It is important to identify factors associated with failed collection for appropriate counselling and justifying pre-emptive use of stem cell mobilizing agents.

CD34+ stem cell counting using labeled immobilized anti-CD34 antibody onto magnetic nanoparticles and EasyCounter BC image cytometer

The ability of immobilized conjugate anti-CD34⁺ monoclonal antibody-dR110 and free conjugate anti-CD45⁺ monoclonal antibody-ATTO620 to precisely enumerate CD34⁺ stem cells and CD45⁺ cells in apheresis samples were evaluated. The conjugates anti-CD34⁺ antibody-dR110 and anti-CD45⁺- antibody-ATTO620 were prepared. Functionalized magnetic nanoparticles (MNPs) were synthesized. The anti-CD34⁺ antibody-dR110 conjugate was immobilized on the modified MNPs using a carbodiimide method. The stem cell count in thawed apheresis samples was determined using the free and the immobilized conjugate anti-CD34⁺ antibody-dR110 on MNPs and an image cell counter EasyCounter BC. A higher stem cell count and more accurate results were obtained with the immobilized conjugate, because a separation and concentration of the stem cells bound to antibody-dR110 on MNPs by external magnet were performed. Coefficients of variation of CD34⁺ cell count in apheresis samples, determined by EasyCounter BC, were ranged from 5.5 to 6.9% and those of CD45⁺ cell count from 3.8 to 4.7%. The viability of CD34⁺ cells was high from 98.5 to 99.6%. It was found that correlation coefficient between the flow cytometer and automatic cell counter, using free anti-CD34⁺ antibody-dR110 was 0.94, and when using immobilized anti-CD34⁺antibody-dR110 on MNPs, the correlation coefficient was 0.97.

A study to compare Hematopoietic Progenitor Cell count determined on a next-generation automated cell counter with flow cytometric CD34 count in peripheral blood and the harvested peripheral blood stem cell graft from autologous and allogenic donors

INTRODUCTION

A successful bone marrow transplant requires a minimum of 2-4 × 10⁶ cells/kg patient body weight of CD 34+ cells to be transfused, where peripheral blood CD34+ cell count being and ideal predictor. We compared the correlation and predictive capacity of both hematopoietic progenitor cell count (HPC) determined on the Sysmex XN-9000 and flow cytometric CD34 in autologous and allogenic donors.

METHODS

Autologous and allogenic donors were taken as per criteria. TLC (Total Leukocyte Count), MNC (Mononuclear cell count), HPC, and CD34 assay were done in both the peripheral blood prior to apheresis, and the harvest product postapheresis. Sysmex XN-9000 was used for TLC, MNC, and HPC tests, and a modified ISH-AGE protocol was used to enumerate CD34 by flow cytometry. Statistical analysis was done using SPSS 16.0.

RESULTS

Sixty-seven allogenic and 35 autologous donors were enrolled. 45% were females, and 55% were males. Correlation between HPC and CD34 was found to be 0.887 with P value < .01 in peripheral blood and 0.847 with P value < .01 in the harvested product. On the other hand, TLC had a correlation of 0.424 and 0.520 in peripheral blood and harvested, respectively. MNC had a weak association. The cutoff value for a target dose of 2 × 10⁶ CD34 cells/kg was 37 × 10⁶ /L for pre-HPC. For a target of 4 × 10⁶ CD34 cells/kg, the cutoff value calculated to be 54 × 10⁶ /L (Sensitivity: 85%, Specificity: 89%) for peripheral blood HPC.

CONCLUSION

We conclude that HPC is comparable to CD34 in predicting harvest product's adequacy.

Peripheral Blood Stem Cell Harvest HPC Count Is an Effective Surrogate Marker for CD34+ Cell Count in Allogeneic Stem Cell Transplant Setting

OBJECTIVE: We assessed the predictive potential of XN-HPC for CD34+ cell count as obtained through Sysmex automated hematology analyzers (XN-1000). METHODS: This study was conducted at the National Institute of Blood Diseases and Bone Marrow Transplantation in 84 donors between December 2012 and December 2017 in the first phase and later validated in 112 donors between December 2017 and December 2018. Sysmex XN-1000 and BD FACS Calibur estimated XN-HPC and CD34+ cells of peripheral blood apheresis product, respectively. Spearman's correlation was assessed between XN-HPC and CD34+ cell count followed by receiver operating characteristic curve calculation to determine the XN-HPC cutoff for a CD34+ count of ≥2 million cells/kg of recipient's body weight RESULTS: There is a moderately positive correlation (P value = .003) between XN-HPC and CD34+ count. Receiver operating characteristic curve analyses demonstrated that a cutoff value for XN-HPC of ≥1·845×10⁶cells/kg of recipient's body weight has a specificity and sensitivity of 100% and 78·2%, respectively, for predicting the CD34+ count of ≥2 million cells/kg of recipient's body weight. This cutoff value of XN-HPC was prospectively validated in 112 donors. The positive predictive value was found to be 100%, while negative predictive value was 17%. CONCLUSION: XN-HPC has a highly promising potential to serve as a cost-effective and time-saving surrogate for CD34+ cell count.

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.

Enumeration of CD34-positive Stem Cells Using the ADAMII Image-based Fluorescence Cell Counter

Background

It is very important to accurately enumerate CD34-positive (CD34+) cells for successful hematopoietic stem cell transplantation (HSCT). We evaluated the ability of the newly developed image based-immunofluorescence cell counter ADAMII (NanoEntek, Seoul, Korea) to enumerate CD34+ cells, which was improved through simultaneous CD45 analysis.

Methods

We enumerated CD34+ cells with ADAMII using 19 peripheral blood (PB) and 91 leukapheresis samples from HSCT donors. Analytical performance, including precision and linearity, was analyzed, and sample stability during storage was evaluated. Viable CD34+ cell count (vCD34) and viable CD45+ cell count (vCD45) and the percentage of viable CD34+ cells among viable CD45+ cells (CD34/CD45) as measured by ADAMII were compared with the corresponding values from two flow cytometry assays, using regression analysis.

Results

ADAMII demonstrated acceptable precision, as CV values of vCD34 from six samples with different counts were all <10% (range: 3.49–9.51%). CV values of the vCD45 and CD34/45 ranged from 4.03% to 9.67% and from 2.48% to 10.07%, respectively. The linearity of vCD34 showed an excellent R² value (0.99) when analyzed using the intended count and flow cytometry data. The ADAMII and two flow cytometry-based assays generated very similar data for the PB and leukapheresis samples.

Conclusions

ADAMII demonstrated excellent performance for use as a routine clinical assay in terms of CD34+ cell enumeration from PB and leukapheresis samples. Moreover, it could be used as a point-of-care-test for determining mobilization time and predicting an adequate apheresis stem cell product.

The value of the post-thaw CD34+ count with and without DMSO removal in the setting of autologous stem cell transplantation

BACKGROUND

CD34+ cell count correlates with engraftment potency after autologous stem cell transplantation. Assessment of CD34+ mainly occurs after apheresis and before cryopreservation with dimethyl sulfoxide (DMSO). The influence of postthaw CD34+ cell numbers over time to engraftment is not well studied, and determination of postthaw CD34+ cell counts is challenging for a variety of reasons. The aim of this retrospective study was to systematically assess the value of postthaw CD34+ cell counts in autologous grafts with and without DMSO removal.

STUDY DESIGN AND METHODS

Between January 2008 and December 2015, 236 adult patients underwent a total of 292 autologous stem cell transplantations. Median age at transplantation was 56 years, and the main indication was multiple myeloma (60%). DMSO removal was done in 96 grafts (33%), either by centrifugation or by Sepax method.

RESULTS

Patients receiving grafts containing DMSO showed a significantly faster platelet (p = 0.02) and RBC (p = 0.001) engraftment. DMSO removal was not associated with fewer infusion-related adverse events. We observed a good correlation between CD34+ cell count after apheresis and CD34+ cell count after thawing/washing (r = 0.931). Ninety grafts (31%) showed a significant loss of viable CD34+ cells, which translated into a delayed engraftment.

CONCLUSION

DMSO removal was associated with delayed platelet and RBC engraftment without preventing adverse events. CD34+ cell enumeration after thawing remains difficult to perform, but grafts showing higher cell loss during cryopreservation and thawing are associated with slower engraftment. Prospective studies on the role of DMSO removal and postthaw CD34+ enumeration using defined protocols are needed.

Quantification of peripheral blood CD34+ cells prior to stem cell harvesting by leukapheresis: a single center experience

Background

Due to laboratory logistic issues, our center has traditionally scheduled peripheral blood stem cell harvests based on timing from the start of mobilization. This has proved to be useful in some cases, but also resulted in many fruitless harvests due to poor mobilization. In order to improve the efficiency of collections and compare the effectiveness of peripheral blood CD34⁺ cells as a predictor with data from other reports, this study analyzed the implementation of this routine.

Methods

Peripheral blood and leukapheresis samples were quantified by flow cytometry and the association between these parameters was assessed.

Results

Sixty-six consecutive leukapheresis samples were collected from 34 patients after the collection of peripheral blood samples for CD34⁺ quantification. A moderate positive correlation was observed between peripheral blood CD34⁺ cell count and total CD34⁺ cell count/kg (r = 0.596; p-value < 0.001). A multivariable regression model also confirmed this association and allowed the estimation that for every increase in five CD34⁺ cells/μL in the peripheral blood, a mean increase of 0.38 × 10⁶ CD34⁺ cells/kg could be predicted. Demographic characteristics, baseline comorbidities and mobilization regimen did not influence final CD34⁺ cell count in this sample.

Conclusions

As observed in other centers, quantification of peripheral blood CD34⁺ progenitor cells is a strong predictor of effectiveness to guide stem cell harvesting. Due to the results of this study, a modification in the peripheral blood stem cell harvesting logistics was implemented at our center in order to incorporate this routine.

Selection of Tissue Factor-Deficient Cell Transplants as a Novel Strategy for Improving Hemocompatibility of Human Bone Marrow Stromal Cells

Intravascular transplantation of tissue factor (TF)-bearing cells elicits an instant blood-mediated inflammatory reaction (IBMIR) resulting in thrombotic complications and reduced engraftment. Here we studied the hemocompatibility of commonly used human white adipose tissue (WAT), umbilical cord (UC) and bone marrow stromal cells (BMSC) and devised a possible strategy for safe and efficient stromal cell transplantation.

Methods: Stromal cell identity, purity, and TF expression was tested by RTQ-PCR, flow cytometry and immunohistochemistry. Pro-coagulant activity and fibrin clot formation/stabilization was measured In Vitro by viscoelastic rotational plasma-thromboelastometry and in vivo by injecting sorted human stromal cells intravenously into rats. The impact of TF was verified in factor VII-deficient plasma and by sort-depleting TF/CD142⁺ BMSC.

Results: We found significantly less TF expression by a subpopulation of BMSC corresponding to reduced pro-coagulant activity. UC and WAT stroma showed broad TF expression and durable clotting. Higher cell numbers significantly increased clot formation partially dependent on coagulation factor VII. Depleting the TF/CD142⁺ subpopulation significantly ameliorated BMSC's hemocompatibility without affecting immunomodulation. TF-deficient BMSC did not produce thromboembolism in vivo, comparing favorably to massive intravascular thrombosis induction by TF-expressing stromal cells.

Conclusion: We demonstrate that plasma-based thromboelastometry provides a reliable tool to detect pro-coagulant activity of therapeutic cells. Selecting TF-deficient BMSC is a novel strategy for improving cell therapy applicability by reducing cell dose-dependent IBMIR risk. The particularly strong pro-coagulant activity of UC and WAT preparations sounds an additional note of caution regarding uncritical systemic application of stromal cells, particularly from non-hematopoietic extravascular sources.

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.

[Absolute numbers of peripheral blood CD34+ hematopoietic stem cells prior to a leukapheresis procedure as a parameter predicting the efficiency of stem cell collection]

AIM

To identify a parameter predicting a collection of at least 2·106 CD34+ hematopoietic stem cells (HSC)/kg body weight per leukapheresis (LA) procedure.

SUBJECTS AND METHODS

The investigation included 189 patients with hematological malignancies and 3 HSC donors, who underwent mobilization of stem cells with their subsequent collection by LA. Absolute numbers of peripheral blood leukocytes and CD34+ cells before a LA procedure, as well as a number of CD34+ cells/kg body weight (BW) in the LA product stored on the same day were determined in each patient (donor).

RESULTS

There was no correlation between the number of leukocytes and that of stored CD34+ cells/kg BW. There was a close correlation between the count of peripheral blood CD34+ cells prior to LA and that of collected CD34+ cells calculated with reference to kg BW.

CONCLUSION

The optimal absolute blood CD34+ cell count was estimated to 20 per µl, at which a LA procedure makes it possible to collect 2·106 or more CD34+ cells/kg BW.

Blood Stem Cell Collection: Factors Influencing the Recovery of Granulocyte-Macrophage Colony Forming Cells

We evaluated data from all blood cell (BC) collections performed in our institution between 1989 and 1995 to determine factors influencing the outcome of collection. One hundred and thirty-three collections were performed on 106 patients. Malignant diagnoses were: non-Hodgkins lymphoma (NHL) in 35%, multiple myeloma in 31%, breast cancer in 26%, and Hodgkin's disease in 8%. Collections were obtained routinely in myeloma and breast cancer and due to bone marrow involvement with malignancy or inaspirable bone marrow in lymphoma patients. Collections were obtained on a Cobe Spectra or Baxter-Fenwall CS3000+. Engraftment potential was determined by methylcellulose colony assay (CFU-GM), with a target of >10 × 104 CFU-GM/kg. Apheresis nucleated cell count correlated significantly, albeit weakly (r = 0.26), with CFU-GM with a cell count of >5 × 10s/kg resulting in an adequate number of CFU-GM in 78% of patients. In univariant analysis outcome of collection was significantly influenced by the patients age (p = 0.01), malignant diagnosis (p < 0.001), reason for collection (p = 0.002), and the mobilization regimen (p = 0.01). The nature of the apheresis device used did not influence outcome. Only malignant diagnosis was significant (p < 0.001) in multivariate analysis. We conclude that the outcome of BC is most strongly influenced by patient factors such as malignant diagnosis. These factors must be considered when comparing the outcome of different mobilization regimens and when planning collection strategies.

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.

Novel strategies of adoptive immunotherapy: How natural killer cells may change the treatment of elderly patients with acute myeloblastic leukemia

Although many attempts have been made to identify novel molecular-targeted therapies for patients with acute myeloid leukemia, their translation into the clinic have had limited impact. In particular, the question of effective and curative treatments for elderly patients, who are not eligible for stem cell transplantation, remains an unmet medical need. To answer this question, a wide range of immunologic therapeutic strategies, mostly T cell based, have been proposed and investigated. At present, however, the clinical results have been largely unsatisfactory. Natural killer cells have recently been used as a means of adoptive immunotherapy with promising clinical results. On the basis of recent clinical reports and moving from the basic immunobiology of natural killer cells, here we discuss some open issues in the clinical translation of natural killer-based adoptive immunotherapy for the management of elderly patients with acute myeloid leukemia.

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.

Relapse risk after autologous stem cell transplantation in patients with lymphoma based on CD34+ cell dose

It is unclear whether higher CD34 + cell doses infused for ASCT have any influence on survival or relapse in patients with lymphoma. We analyzed the correlation of infused CD34 + cell dose with relapse, survival, and hematopoietic recovery in 146 consecutive patients undergoing ASCT for lymphoma. Higher doses (>5 × 10⁶/kg) were significantly correlated with earlier hematopoietic recovery, fewer infectious episodes, lower transfusion needs. No differences were observed in lymphoma outcomes (4-year relapse incidence of 38% [95%CI: 29%-48%] in the lower dose group versus 51% [95%CI: 30%-69%] in the higher dose group, 10-year OS probabilities of 58% [95%CI: 48%-68%] versus 75% [95%CI: 59%-91%], 10-year DFS probabilities of 47% [95%CI: 37%-57%] versus 42% [95%CI: 23%-61%], p = NS for all outcomes). In this series, a higher infused CD34 + cell dose did not correlate with survival or relapse but correlated with earlier hematopoietic recovery and lower resource consumption.

Autologous peripheral blood stem cell harvest: Collection efficiency and factors affecting it

BACKGROUND

Harvest of hematopoietic progenitor cells via leukapheresis is being used increasingly for transplants in India. Adequate yield of cells per kilogram body weight of recipient is required for successful engraftment. Collection efficiency (CE) is an objective quality parameter used to assess the quality of leukapheresis program. In this study, we calculated the CE of the ComTec cell separator (Fresenius Kabi, Germany) using two different formulae (CE1 and CE2) and analyzed various patient and procedural factors, which may affect it.

MATERIALS AND METHODS

One hundred and one consecutive procedures in 77 autologous donors carried out over 3 years period were retrospectively reviewed. Various characteristics like gender, age, weight, disease status, hematocrit, preprocedure total leukocyte count, preprocedure CD34 positive (CD34+) cells count, preprocedure absolute CD34+ cell count and processed apheresis volume effect on CE were compared. CE for each procedure was calculated using two different formulae, and results were compared using statistical correlation and regression analysis.

RESULTS

The mean CE1 and CE2 was 41.2 and 49.1, respectively. CE2 appeared to be more accurate indicator of overall CE as it considered the impact of continued mobilization of stem cells during apheresis procedure, itself. Of all the factors affecting CE, preprocedure absolute CD34+ was the only independent factor affecting CE.

CONCLUSION

The only factor affecting CE was preprocedure absolute CD34+ cells. Though the mean CE2 was higher than CE1, it was not statistically significant.

Efficacy of biosimilar granulocyte colony-stimulating factor versus originator granulocyte colony-stimulating factor in peripheral blood stem cell mobilization in de novo multiple myeloma patients

BACKGROUND AIMS

Filgrastim and lenograstim are the standard granulocyte colony-stimulating factor (G-CSF) agents for peripheral blood stem cell mobilization (PBSC) in patients who undergo autologous stem cell transplantation.

METHODS

To assess whether biosimilars are effective, we conducted a single-center, prospective study that included 40 consecutive de novo multiple myeloma patients who received cyclophosphamide 4 g/m(2) per day plus biosimilar filgrastim G-CSF to mobilize PBSC. These patients were compared with a group of 37 patients matched for age, diagnosis, previous chemotherapy and mobilization who had been treated with originator G-CSF. The mean number of CD34+ cells/μL in the peripheral blood was 199.6 ± 207.4 in the biosimilar and 192.8 ± 154.7 in the originator group (P = 0.87). The median number of CD34+ cells/kg recipient collected was 11.5 ± 5.8 and 12.3 ± 5.3 in the biosimilar and originator groups, respectively (P = 0.51). The mobilization failure rate was 2.5% and 2.7% in the biosimilar filgrastim and originator filgrastim cohorts (P = NS), respectively.

RESULTS

Twenty-nine patients in the biosimilar group and 28 patients in the originator group underwent autologous transplantation. There were no statistically significant differences between the biosimilar and originator G-CSF cohorts in terms of hematopoietic recovery parameters and transplant-related toxicities.

CONCLUSIONS

The efficacy of biosimilar G-CSF appears to be equivalent to the reference G-CSF.

Evaluation of new automated hematopoietic progenitor cell analysis in the clinical management of peripheral blood stem cell collections

BACKGROUND

Successful peripheral blood stem cell transplantation (PBSCT) depends on the collection and infusion of adequate numbers of peripheral blood progenitor cells (PBPCs). Several predictors of PBPC yield are used currently, including white blood cell (WBC) count and CD34 analysis. This study evaluated the utility of the new automated hematopoietic progenitor cell count available on Sysmex XN hematology analyzers (XN-HPCs) in PBSCT.

STUDY DESIGN AND METHODS

The performance characteristics of XN-HPC, CD34+, and WBC analysis were compared using 107 matched peripheral blood and apheresis samples.

RESULTS

Good correlation was observed between XN-HPC and CD34+ cell counts in peripheral blood (r = 0.88; slope, 0.81) and apheresis collections (r = 0.91; slope, 0.89). Moreover, peripheral blood XN-HPC and CD34 analysis showed comparable ability to predict successful PBPC harvests (≥2 × 10(6) CD34+ cells/kg). At a cutoff of 20 × 10(6) progenitor cells/L, peripheral blood XN- HPC and CD34 analysis both showed negative predictive values (NPVs) of 100% and positive predictive values (PPVs) of 55.4 and 63%, respectively. Using an optimized cutoff of 38 × 10(6) progenitor cells/L, derived from receiver operating characteristic analysis, the PPV for XN-HPC and CD34 analysis increased to 71.4 and 78.9%, respectively, with relatively unchanged NPVs (XN-HPC 97.7%, CD34+ 98.0%). In contrast, the correlation between peripheral blood WBC and CD34 analysis was poor (r = 0.48; slope, 669.85), and the peripheral blood WBC count (cutoff, 10 × 10(9) /L) was a poor predictor of PBPC harvest (NPV 60%, PPV 43.1%).

CONCLUSION

XN-HPC compares favorably with CD34 analysis and may be a surrogate for CD34 analysis to predict optimal timing of PBPC collections.

Efficacy of just-in-time plerixafor rescue for Hodgkin's lymphoma patients with poor peripheral blood stem cell mobilization

BACKGROUND

Plerixafor is a Food and Drug Administration-approved agent for improving peripheral blood stem cell (PBSC) mobilization in filgrastim (granulocyte-colony-stimulating factor [G-CSF])-stimulated patients with multiple myeloma and non-Hodgkin's lymphoma. Limited information is available on its use in Hodgkin's lymphoma (HL) patients. We describe our experience with plerixafor as an immediate rescue agent in HL patients with poor PBSC mobilization.

STUDY DESIGN AND METHODS

We retrospectively reviewed the collection data of 27 consecutive HL patients at our center in whom plerixafor was added to rescue a failing PBSC collection after G-CSF and chemotherapy (26) or G-CSF alone (1). Plerixafor was added in 11 patients due to peripheral blood (PB) CD34+ counts that persisted below the threshold (>10 × 10(6) /L) to initiate collection (median, 1.47 × 10(6) ; range 0 × 10(6) -6.28 × 10(6) /L) and in 16 patients due to low collection yields, who had a median yield of 0.33 × 10(6) (0.14 × 10(6) -0.65 × 10(6) ) CD34+ cells/kg on the last collection before plerixafor administration.

RESULTS

After a median of 2 (range, 2-4) collections with plerixafor, the patients collected a median of 1.82 × 10(6) (0.52 × 10(6) -11.14 × 10(6) ) CD34+ cells/kg. The addition of plerixafor enabled 20 patients (74.1%) to reach the 2.0 × 10(6) CD34+ cells/kg minimum required for autologous stem cell transplantation (ASCT) during the same collection cycle. Subsequent remobilization in three patients with plerixafor enabled all three to reach this goal.

CONCLUSION

Plerixafor can be used in HL patients with poor mobilization as a rescue agent and boosts mobilization sufficiently in most patients in the same collection attempt, thus not only permitting ASCT, but also avoiding remobilization and the associated costs, treatment delays, and patient inconvenience.

Hematopoietic stem and progenitor cell mobilization in mice

Hematopoietic stem cell transplantation (HSCT) can be performed with hematopoietic stem and progenitor cells (HSPC) acquired directly from bone marrow, from umbilical cord blood or placental tissue, or from the peripheral blood after treatment of the donor with agents that enhance egress of HSPC into the circulation, a process known as "mobilization." Mobilized peripheral blood stem cells (PBSC) have become the predominate hematopoietic graft for HSCT, particularly for autologous transplants. Despite the success of PBSC transplant, many patients and donors do not achieve optimal levels of mobilization. Thus, accurate animal models and basic laboratory investigations are needed to further investigate the mechanisms that lead to PBSC mobilization and define improved or new mobilizing agents and/or strategies to enhance PBSC mobilization and transplant. This chapter outlines assays and techniques for exploration of hematopoietic mobilization using mice as a model organism.

Plerixafor to the rescue: boosting peripheral blood stem cell mobilization in patients previously treated with hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone/methotrexate, cytarabine (Hyper-CVAD) chemotherapy

Hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone/methotrexate, cytarabine (Hyper-CVAD) chemotherapy exerts deleterious effects on peripheral blood stem cell (PBSC) mobilization. We retrospectively reviewed the use of plerixafor to salvage mobilization in 18 Hyper-CVAD treated patients who initially mobilized poorly with chemotherapy and granulocyte colony stimulating factor (G-CSF). After plerixafor administration the median peripheral blood (PB) CD34 + count rose from 3.74/μL (0-17/μL) to 6.85/μL (0-47.2/μL). The patients collected a median of 1.64 (0.21-5.56) × 10(6) CD34 + cells/kg with a median number of 3 (1-4) doses in the same collection cycle, and 11 patients reached the 2.0 × 10(6) CD34 + cells/kg minimum required for transplant. Six patients were remobilized later with G-CSF and plerixafor, and three additional patients reached this goal. For these 14 patients the median number of doses of plerixafor required to reach 2.0 × 10(6) CD34 + cells/kg was 3 (range 1-4). In conclusion, plerixafor can be utilized successfully in many cases to overcome the effects of Hyper-CVAD on PBSC mobilization.

Stem cell mobilization in HIV seropositive patients with lymphoma

High-dose chemotherapy with autologous peripheral blood stem cell rescue has been reported as feasible and effective in HIV-associated lymphoma. Although a sufficient number of stem cells seems achievable in most patients, there are cases of stem cell harvest failure. The aim of this study was to describe the mobilization policies used in HIV-associated lymphoma, evaluate the failure rate and identify factors influencing mobilization results. We analyzed 155 patients who underwent attempted stem cell mobilization at 10 European centers from 2000-2012. One hundred and twenty patients had non-Hodgkin lymphoma and 35 Hodgkin lymphoma; 31% had complete remission, 57% chemosensitive disease, 10% refractory disease, 2% untested relapse. Patients were mobilized with chemotherapy + G-CSF (86%) or G-CSF alone (14%); 73% of patients collected >2 and 48% >5 × 10(6) CD34(+) cells/kg. Low CD4+ count and refractory disease were associated with mobilization failure. Low CD4(+) count, low platelet count and mobilization with G-CSF correlated with lower probability to achieve >5 × 10(6) CD34(+) cells/kg, whereas cyclophosphamide ≥ 3 g/m(2) + G-CSF predicted higher collections. Circulating CD34(+) cells and CD34/WBC ratio were strongly associated with collection result. HIV infection alone should not preclude an attempt to obtain stem cells in candidates for autologous transplant as the results are comparable to the HIV-negative population.

Predictors of the yield of mobilized peripheral blood CD34+ cells in HLA-matched sibling donor

We examined the donor factors that may affect the yield of peripheral blood stem cell (PBSC) mobilized from healthy donors. Pre-apheresis PB-CD34(+) cell count was the only factor that correlated with PBSC yield. Leukocyte count (LC) and monocyte count (MC) correlated with PB-CD34(+) cell. Male gender and PB-CD34(+) cell count of at least 87.1/μL and 69.8/μL on day-4 and -5 of G-CSF were associated with the ability to harvest at least 5×10(6)/kg CD34(+) cells after one apheresis. We concluded that gender and PB-CD34(+) cell count are important predictors of PBSC yield. LC and MC may serve as surrogate markers for estimating the PB-CD34(+) cell count.

Mobilization of hematopoietic progenitor cells with granulocyte colony stimulating factors for autologous transplant in hematologic malignancies: a single center experience

BACKGROUND

In 2006 the Hematology Service of Hospital Maciel published its experience with peripheral blood progenitor cell harvesting for autologous stem cell transplantation using Filgen JP (Clausen Filgrastim). After mobilization with a mean filgrastim dose of 78 mcg/Kg, 4.7 x 10(6) CD34(+) cells/Kg were obtained by apheresis. Age above 50, multiple myeloma as underlying disease and a malignancy that was not in remission were identified as frequent characteristics among patients showing complex mobilization.

OBJECTIVE

The aim of this study was to compare stem cell mobilization using different brands of filgrastim.

METHODS

One hundred and fifty-seven mobilizations performed between 1997 and 2006 were analyzed. This retrospective analysis comparative two groups of patients: those mobilized with different brands of filgrastim (Group A) and those who received Filgen JP (Clausen Filgrastim) as mobilizing agent (Group B). A cluster analysis technique was used to identify four clusters of individuals with different behaviors differentiated by age, total dose of filgrastim required, number of apheresis and harvested CD34(+) cells.

RESULTS

The mean total dose of filgrastim administered was 105 mcg/Kg, the median number of apheresis was 2 procedures and the mean number of harvested stem cells was 4.98 x 10(6) CD34(+) cells/Kg. No significant differences were observed between Groups A and B regarding the number of apheresis, harvested CD34(+) cells and number of mobilization failures, however the total dose of filgrastim was significantly lower in Group B.

CONCLUSIONS

Among other factors, the origin of the cytokine used as mobilizing agent is an element to be considered when evaluating CD34(+) cell mobilization results.

Second time a charm? Remobilization of peripheral blood stem cells with plerixafor in patients who previously mobilized poorly despite using plerixafor as a salvage agent

BACKGROUND

Plerixafor is a recently introduced agent used to improve peripheral blood stem cell (PBSC) mobilization in patients with hematologic malignancies. However, some patients still cannot mobilize adequately even with plerixafor.

STUDY DESIGN AND METHODS

We retrospectively reviewed the PBSC collections of 18 consecutive lymphoma and multiple myeloma patients, who had previously mobilized poorly despite the use of plerixafor and received plerixafor again during remobilization.

RESULTS

During the first mobilization attempt, all 18 recombinant granulocyte-colony-stimulating factor (G-CSF; two) or G-CSF plus chemotherapy-mobilized patients (16) had poor response to plerixafor, with peripheral blood (PB) CD34+ counts ranging from 0 to 7.48 × 10(6)/L after the first dose. They collected only 0.15 × 10(6) to 1.63 × 10(6) (median, 0.40 × 10(6)) CD34+ cells/kg after one to four collections. The median average daily yield was 0.24 × 10(6) CD34+ cells/kg. Remobilization began 1 to 4 weeks later with G-CSF, plerixafor, and with (three) or without (15) cyclophosphamide. The PB CD34+ cell counts after the first dose of plerixafor were 3.04 × 10(6) to 127.54 × 10(6)/L (median, 14.58 × 10(6)/L). After one to four doses of plerixafor, each patient collected an additional 0.39 × 10(6) to 14.02 × 10(6) (median, 1.89 × 10(6)) CD34+ cells/kg, and the median daily average was 0.78 × 10(6) CD34+ cells/kg. Cumulatively, after two rounds of collections, 15 collected more than 2.0 × 10(6) CD34+ cells/kg. Thirteen have proceeded to autologous stem cell transplantation (ASCT) and successfully engrafted.

CONCLUSION

In patients who had responded poorly to the use of plerixafor as a mobilization salvage agent, response to remobilization with plerixafor for the second time was variable, but most (83.3%) patients were able to collect enough PBSCs to proceed to ASCT.