Evaluation of an algorithm based on peripheral blood hematopoietic progenitor cell and CD34+ cell concentrations to optimize peripheral blood progenitor cell collection by apheresis

Hematopoietic progenitor cell count as a potential quantitative marker in apheresis products during allogeneic stem cell transplantation

BACKGROUND

The quality and quantity of hematopoietic stem cells in apheresis products are essential to the success of peripheral blood hematopoietic stem cell transplantation (PB-HSCT). While the flow cytometry measurement of CD34+ cells as a golden standard for stem cell count is labor and cost-intensive, hematopoietic progenitor cell number evaluated by XN Sysmex series automated hematology analyzers (XN-HPC) is suggested as a surrogate marker.

MATERIALS AND METHODS

We evaluated the correlation and consistency of XN-HPC and CD34+ cell count in apheresis samples from both allogeneic donors and autologous patients during PB-HSCT.

RESULTS

Good correlation and consistency were observed between XN-HPC and CD34+ cell counts in harvests collected from healthy donors (R = .852) rather than autologous patients (R = .375). Subgroup analysis showed that the correlation was especially poor when autologous patients used plerixafor as an additional mobilizer or were diagnosed with multiple myeloma (MM). In the setting of allogeneic transplantation, the correlation coefficients were even better in samples from non-first-round apheresis (R = .951), with high white blood cell (WBC) counts (R = .941), or having successful engraftment within 2 weeks (R = .895). ROC analysis suggested that an optimal XN-HPC count of 1127 × 106 /L best predicted a sufficient yield of CD34+ stem cells, with diagnostic sensitivity and specificity being 92% and 72%, respectively (AUC = 0.852).

CONCLUSIONS

XN-HPC is a sufficient quantitative marker for stem cell assessment of harvest yield in allogeneic but not autologous HSCT.

Retrospective comparison of two different cell separators for autologous peripheral blood stem cell collection: Single center experience

INTRODUCTION

Autologous peripheral blood stem cell (PBSC) transplantation has become a standard treatment option for certain hematological malignancies. The collection of PBSCs for transplantation is a well-established process and the effectiveness can vary depending on the cell separator.  We aimed to compare the effectivity of two  devices, the Spectra Optia and the Amicus for autologous PBSC collection. We also evaluated the effect of the peripheral white blood cell (WBC) count on the CD34+ collection efficiency (CE2).

METHODS

We retrospectively evaluated 262 apheresis procedures performed in patients between 2015 and 2021 at the Apheresis Unit of our transplantation center. The PBSCs were collected by the Spectra Optia cell separator with continuous Mononuclear Collection (cMNC) (128 procedures) or the Amicus (MNC) (134 procedures). In addition to the apheresis parameters and product characteristics, we also evaluated the effect of the pre-apheresis peripheral WBC count on the CE2.

RESULTS

There was no significant difference in the CD34+ CE2 between the Spectra Optia and Amicus devices (median 65.06% and 68.24%, respectively, p = 0.070). In the Amicus group, the CE2 ratio was found to be statistically significantly higher in patients with a pre-apheresis peripheral WBC count of 15 × 10⁹/L (median 81.70%, 68.06%, 61.35% and 58.13%, respectively, p < 0.001).

CONCLUSION

While both devices collected autologous PBSC effectively and safely, the Amicus provided a higher rate of CE2 at low pre-apheresis WBC counts. To our knowledge, this is the first study to evaluate the CE2 in autologous PBSC collection devices based on pre-apheresis WBC counts.

Correlation between peripheral blood automated hematopoietic progenitor cell counts and flow cytometric CD34+ cell counts differs according to diagnosis in patients undergoing autologous peripheral blood stem cell transplantation

BACKGROUND

An automated hematopoietic progenitor cell count measurement in Sysmex XN analyzer (XN-HPC) has been developed to assist flow cytometry CD34⁺ cell count measurement, which requires technical expertise and a long turnaround time. Here, we evaluated the correlation between XN-HPC count and flow cytometric CD34⁺ cell count in pre-harvest peripheral blood (PB) samples from patients undergoing autologous peripheral blood stem cell (PBSC) transplantation according to diagnosis and investigated the possible cause of the decreased correlation in plasma cell neoplasm patients.

MATERIALS AND METHODS

We retrospectively included 399 patient data that had matched PB XN-HPC count and CD34⁺ cell count of PB and apheresis product from Samsung Medical Center (SMC) and the Hematopoietic Stem Cell (HSC) registry. We assessed the diagnostic accuracy and the potential cutoff values of XN-HPC count for predicting adequate PBSC collection.

RESULTS

The PB XN-HPC count was 1.6 and 1.3-fold higher than the CD34⁺ cell count in SMC (25.0 vs 15.9/μl) and the HSC registry (20.0 vs 15.2/μl), respectively. Overall the correlation between the PB XN-HPC and CD34⁺ cell count was moderate (SMC, r = 0.71; HSC registry, r = 0.66). A significant proportional and systemic bias with overestimation of XN-HPC count were noted in the plasma cell neoplasm patients in both SMC and the HSC registry. However, no significant difference in correlation was observed according to myeloma-related laboratory parameters in plasma cell neoplasm patients.

CONCLUSION

Our results suggest that XN-HPC count should be interpreted cautiously in cancer patients undergoing autologous PBSC transplantation, especially in those with plasma cell neoplasm.

Analysis of laboratory parameters for optimal autologous peripheral blood stem cell collection from lymphoma and myeloma patients

BACKGROUND

Peripheral blood stem cell (PBSC) collection is important for successful hematopoietic stem cell transplantation. This study aimed to investigate the laboratory parameters associated with the optimal timing of autologous PBSC collection from lymphoma and multiple myeloma patients.

METHODS

We retrospectively evaluated data from 1105 PBSC apheresis procedures performed on 379 adult patients at the National Cancer Center between June 2005 and December 2019. Laboratory parameters, including cutoff values for the number of hematopoietic progenitor cells (HPCs) and circulating CD34+ cells, were analyzed to determine their association with CD34+ cell yield.

RESULTS

The pre-apheresis HPC and CD34+ cell count were statistically significant variables associated with harvested CD34+ cell in lymphoma and MM patients. The optimal cutoff values were 18 × 10⁶ /L for pre-HPC count (66.8% sensitivity, 66.4% specificity) and 11/μL for pre-CD34+ cell count (85.8% sensitivity, 87.2% specificity), to achieve CD34+ cell yields ≥ 1.0 × 10⁶ /kg for each apheresis procedure. Moreover, the optimal cutoff values were 23 × 10⁶ /L for pre-HPC count (71.0% sensitivity, 69.0% specificity) and 18/μL for pre-CD34+ cell count (87.5% sensitivity, 86.3% specificity) to achieve CD34+ cell yields ≥ 2.0 × 10⁶ /kg for each apheresis procedure.

CONCLUSION

HPC count is a potential surrogate marker for monitoring the starting time for PBSC collection. Applying cutoff values for the number of HPC and CD34+ cells may be clinically useful for optimizing the timing of PBSC collection.

Comparison of spectra optia and amicus cell separators for autologous peripheral blood stem cell collection

INTRODUCTION

Autologous peripheral blood stem cell (PBSC) transplantation has become a standard treatment option for many oncology patients. The aim of this study was to evaluate the performance of two cell separators, Spectra Optia (Terumo BCT, Japan) and Amicus (Fresenius-Kabi) for autologous PBSC collection.

METHODS

We retrospectively evaluated 56 apheresis by Spectra Optia with Continuous Mononuclear Cell Collection (cMNC) from 20 patients, and 50 apheresis by Amicus from 27 patients between December 2018 and December 2019. CD34+ collection efficiency (CE2) and platelet (PLT) loss were evaluated.

RESULTS

There was no significant difference in CD34+ CE2 between Spectra Optia with cMNC (median, 28.8%) and Amicus (median, 33.1%; P = 0.537). PLT loss was significantly lower in Amicus (median, 28.6%) than in Spectra Optia with cMNC (median, 37.8%; P = 0.009).

CONCLUSION

CD34+ CE2 was comparable between Spectra Optia and Amicus, and PLT loss was significantly lower in Amicus. To the best of our knowledge, this is the first report comparing autologous PBSC collection of the Spectra Optia and Amicus. These results may provide general guidance with regard to device selection to apheresis clinics that use both separators for optimal outcomes depending on each patient's characteristics.

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.

Comparison of Two Apheresis Systems of COBE and Optia for Autologous Peripheral Blood Stem Cell Collection

Peripheral blood stem cell (PBSC) transplantation following myeloablative therapy is a mainstay of treatment for various types of malignancies. This study aimed to evaluate the differences between the Optia MNC and COBE Spectra MNC systems (Terumo BCT, Japan) according to apheresis procedures and the parameters of apheresis, products, and collection. The clinical data of 74 patients who underwent autologous PBSC collection from July 2012 to July 2015 were reviewed retrospectively. The patients comprised 48 (65%) men and 26 (35%) women with a median age of 56 yr (range, 23–66 yr). Of 216 procedures, 111 (51%) and 105 (49%) were processed by using COBE and Optia MNC, respectively. PBSC collection rates, throughput, numbers of stem cells retrieved, collection efficacy, and platelet loss were compared. There were no significant differences in the median CD34+ cell counts of collected products (0.61×10⁸ vs 0.94×10⁸), CD34 collection efficiency (43.5% vs 42.1%), and loss of platelets (40.1% vs 44.7%). The Spectra Optia MNC apheresis system was comparable to the COBE Spectra system in collecting autologous CD34+ hematopoietic stem cells and retention of platelets.

Autologous Stem Cell Mobilization and Collection

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

Algorithms utilizing peripheral blood hematopoietic progenitor cell counts in lieu of some CD34+ cell counts predict successful peripheral blood stem cell collections with substantial time and cost savings

Background and Objectives

Hematopoietic progenitor cell (HPC) counts from Sysmex hematology analyzers have been shown to correlate with peripheral blood (PB) CD34+ cell counts by flow cytometry. Algorithms utilizing HPC counts to guide stem cell collections have been proposed but rarely tested. This study describes the development and validation of algorithms utilizing HPC and PB CD34+cell counts to predict adequate peripheral blood stem cell (PBSC) collections for chemomobilized and cytokine-mobilized individuals.

Materials and Methods

Utilizing a test set of 83 PB samples from chemomobilized or cytokine-mobilized PBSC collection patients, PB CD34+ counts were correlated with HPC counts and a receiver operating characteristic curve was constructed. Cut-offs of ≤0.5 HPC/μl and ≥7 HPC/μl were established to maximize sensitivity and specificity for using HPC to predict PB CD34+ ≥ 10 cells/μl. These cut-offs were subsequently validated using a separate prospective validation set of 88 HPC/CD34+ cell sample pairs.

Results

Using the algorithms, all patients in the prospective validation data set achieved adequate collections of ≥1 × 10⁶ CD34⁺ cells/kg, and a 67% reduction in the number of CD34⁺ cell counts performed was achieved. This lead to a direct cost savings of at least $18,700 USD over a 21-month period (88% reduction in direct costs).

Conclusion

Use of the algorithms provides significant time and cost savings for the laboratory while accurately predicting (i) timing of PBSC collections to obtain adequate CD34⁺ product yields for chemomobilized patients and (ii) when to administer plerixafor to cytokine-mobilized patients to improve the likelihood of achieving adequate collections.

Plerixafor as preemptive strategy results in high success rates in autologous stem cell mobilization failure

Plerixafor in combination with granulocyte-colony stimulating factor (G-CSF) is approved for autologous stem cell mobilization in poor mobilizing patients with multiple myeloma or malignant lymphoma. The purpose of this study was to evaluate efficacy and safety of plerixafor in an immediate rescue approach, administrated subsequently to G-CSF alone or chemotherapy and G-CSF in patients at risk for mobilization failure. Eighty-five patients mobilized with G-CSF alone or chemotherapy were included. Primary endpoint was the efficacy of the immediate rescue approach of plerixafor to achieve ≥2.0 × 10⁶ CD34⁺ cells/kg for a single or ≥5 × 10⁶ CD34⁺ cells/kg for a double transplantation and potential differences between G-CSF and chemotherapy-based mobilization. Secondary objectives included comparison of stem cell graft composition including CD34⁺ cell and lymphocyte subsets with regard to the mobilization regimen applied. No significant adverse events were recorded. A median 3.9-fold increase in CD34⁺ cells following plerixafor was observed, resulting in 97% patients achieving at least ≥2 × 10⁶ CD34+ cells/kg. Significantly more differentiated granulocyte and monocyte forming myeloid progenitors were collected after chemomobilization whereas more CD19⁺ and natural killer cells were collected after G-CSF. Fifty-two patients underwent transplantation showing rapid and durable engraftment, irrespectively of the stem cell mobilization regimen used. The addition of plerixafor in an immediate rescue model is efficient and safe after both, G-CSF and chemomobilization and results in extremely high success rates. Whether the differences in graft composition have a clinical impact on engraftment kinetics, immunologic recovery, and graft durability have to be analysed in larger prospective studies.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Evaluation of ABX Pentra DX 120 and Sysmex XE-2100 in umbilical cord blood

INTRODUCTION

Cord blood (CB) is an important source of hematopoietic stem cells and reflects the hematologic status of neonates. ABX Pentra DX 120 (Horiba Medical, Montpellier, France) and Sysmex XE-2100 (Sysmex, Kobe, Japan) were compared in 200 CB specimens.

METHODS

Complete blood count parameters including white blood cell (WBC) differential counts were compared between the two analyzers. Double differential matrix (DDX) by ABX Pentra DX 120 and hematopoietic progenitor cell (HPC) by Sysmex XE-2100 were compared with CD34(+) cells by flow cytometry.

RESULTS

Most of the parameters showed acceptable correlation between the two analyzers. Although WBC differential of both analyzers showed acceptable correlation with manual counts, mononuclear cells (MNC) by ABX Pentra DX 120 better correlated with manual count than MNC by Sysmex XE-2100. NRBC by Sysmex XE-2100 better correlated with manual count than NRBC by ABX Pentra DX 120. ABX Pentra DX 120 showed better flagging performances. DDX better correlated with CD34(+) cells than HPC.

CONCLUSION

Although the results from both analyzers are mostly interchangeable and reliable in CB specimens, flagging performance of ABX Pentra DX 120 seems to be superior to that of Sysmex XE-2100. DDX by ABX Pentra DX 120 would be valuable to evaluate the quality of CB for further therapeutic utilization.

Validation of a formula for predicting daily CD34(+) cell collection by leukapheresis

BACKGROUND AIMS

The ability to predict how many CD34(+) cells a donor will collect on a given day is vital for efficient leukapheresis.

METHODS

We validated a formula to predict daily CD34(+) cell collections by leukapheresis, calculated as follows: (peripheral blood CD34(+) cells/L) × (adjusted collection efficiency of 30%)/body weight (kg), multiplied by the number of liters processed. This validation was performed from 234 donors undergoing 30 L large volume leukapheresis (LVL) and 162 donors undergoing smaller collections (non-LVL). The LVL group consisted of 811 collection events (625 multiple myeloma, 186 non-myeloma). The non-LVL group consisted of 224 collection events (196 multiple myeloma, 28 non-myeloma). All predicted and observed CD34(+) cell collection numbers were plotted (predicted versus observed) and assessed using linear regression analyses. Linear correlation coefficients (r-values), slopes and intercepts of the regression lines were evaluated.

RESULTS

Predicted versus observed data points across all quantities of CD34(+) cells/kg collected by both LVL and non-LVL had strong r-values of 0.947 and 0.913, respectively, demonstrating near perfect positive linear correlations. Data for LVL collections subgrouped by number of cells collected (poor, intermediate and good), mobilization regimen, collection day and diagnosis were analyzed the same way and showed consistent findings.

CONCLUSIONS

We have validated a formula with a strong ability to predict collection of CD34(+) cells/kg that would allow for individualization of collection for any donor once the peripheral blood CD34(+) cell count and optimal goal of collection were known; to date this has not been published by other groups.

Immunophenotyping of hematopoietic progenitor cells: Comparison between cord blood and adult mobilized blood grafts

AIM

To study the immunophenotype of hematopoietic progenitor cells from cord blood (CB) grafts (n = 39) in comparison with adult apheresis grafts (AG, n = 229) and pre-apheresis peripheral blood (PAPB) samples (n = 908) using flow cytometry analysis.

METHODS

First, we performed a qualitative analysis of CD34+ cell sub-populations in both CB and PAPB grafts using the standardized ISHAGE protocol and a wide panel of 20 monoclonal antibodies. Next, we studied some parameters, such as the age of mothers and the weight of newborns, which can influence the quality and the quantity of CD34+ cells from CB.

RESULTS

We found that the percentage of apoptotic cells was high in CB in comparison to PAPB (PAPB: 4.6% ± 2.6% vs CB: 53.4% ± 5.2%, P < 0.001). In CB, the weight of newborn and the age of the mother have the influence on CD34+ cells. The follow-up of Ag CD133 in the ISHAGE double platform protocol in association with CD45, CD34 and the 7'AAD shows an equal rate between the two cell populations CD133+CD45+CD34+ high and CD34+CD45+ high with a higher percentage. So, is the inclusion of Ac CD133 necessary in the present panel included in the ISHAGE method? Last part, we showed a significant presence of interferon γ in CB in comparison to PAPB, the annexin showing the high number of apoptotic cells in CB.

CONCLUSION

This study demonstrates that many different obstetric factors must be taken into account when processing and cryo-banking umbilical CB units for transplantation.

Mobilization and collection of peripheral blood stem cells: guidelines for blood volume to process, based on CD34-positive blood cell count in adults and children

We report 189 mobilizations and 489 collections of peripheral blood stem cells (PBSC) performed in 139 autologous transplantation patients and in 28 donors for allogeneic transplantations whose ages ranged from 2-68 years. We observed a correlation (P < .001; Pearson's coefficient 0.64) between CD34-positive cells and granulocyte-macrophage colony-forming units examined to estimate PBSC. In a subset of 287 collections (97 adults and 49 children) we obtained peripheral blood (PB) CD34-positive cell counts at 2 to 4 hours before leukapheresis. We noted a correlation between PB CD34-positive cell counts before leukapheresis and the number of CD34-positive cells per kilogram of body weight collected in the whole apheresis of the day (P < .001; Pearson's coefficient 0.82). An even better correlation was obtained between PB CD34-positive cells preapheresis and the yield of each individual blood volume (BV) processed (P < .001; Pearson's coefficient 0.87). Healthy donors and patients in each age group behaved similarly. In addition, the collection yield was greater among children than adults. These findings allowed us to develop a simple predictive model to estimate the BV to process for a target dose of CD34-positive cells per kilogram, based on the level of PBSC before apheresis in children and adults.

Use of the haematopoietic progenitor cell parameter in optimizing timing of peripheral blood stem cell harvest

BACKGROUND AND OBJECTIVES

Timing of peripheral blood stem cell (PBSC) harvest is typically based on quantification of peripheral blood (PB) CD34+ cells. CD34 enumeration is expensive, requires expertise and takes a minimum of 1-2 h to perform. The Sysmex XE2100 is an automated haematology analyser that can rapidly and inexpensively identify haematopoietic progenitor cell (HPC) populations in PB. The aim of this study was to examine if HPC can be used to optimize timing of PBSC harvest.

MATERIALS AND METHODS

White blood cell (WBC), HPC and CD34 counts were determined in a total of 60 mobilized donors. Data were analysed to examine the utility of WBC and HPC counts in predicting preharvest CD34+ counts.

RESULTS

In adults presenting for autologous collection, a PB HPC threshold of > 30/microl predicts a preharvest CD34+ count of > 20/microl with sensitivity of 86% and positive predictive value (PPV) of 100%. Among paediatric patients with a diagnosis of neuroblastoma, an HPC threshold of > 16/microl yielded sensitivity and PPV of 100%, while in children with other diagnoses, an HPC cut-off of > 44/microl yielded sensitivity and PPV of 67% and 100%, respectively. Eighty per cent of adequately mobilized allogeneic donors were identified using an HPC threshold > 15/microl, with a PPV of 100%. PB WBC can also aid in predicting CD34 counts in most patient groups, albeit with lower sensitivity than HPC.

CONCLUSION

By virtue of being a sensitive and accurate predictor of preharvest CD34+ counts, our data support the use of the HPC parameter in optimizing the timing of PBSC harvest.

Turning CD34 Non-Mobilizers into Mobilizers: A Case Report Involving Plerixafor (AMD3100)

SUMMARY: OBJECTIVE: In a significant proportion of patients with hematologic malignancies (5-30%) poor mobilization of hematopoietic stem cells (HSC) is observed. This compromises the application of effective and potentially curative high-dose chemotherapy (HDC) treatment. CASE REPORT: Here we report the case of a 38-year-old female patient who was treated for recurrent follicular B-cell non-Hodgkin's lymphoma grade III. In this patient, we failed twice to mobilize stem cells using chemotherapy followed by granulocyte-colony stimulating factor (G-CSF). Recently a new chemokine receptor CXCR4 antagonist, AMD3100 (plerixafor), was introduced which can be combined with G-CSF mobilization and has been reported to increase the number of harvested stem cells significantly. Using this protocol, we were able to harvest a HSC product. This product was transplanted 3 weeks after the harvest (after HDC), and the patient had an uncomplicated recovery of granulopoiesis (day 11 after transplantation of autologous HSC). CONCLUSION: Plerixafor has the potency to become an important tool in mobilizing HSC, especially in those patients in whom HSC cannot be mobilized by the combination of G-CSF and chemotherapy alone.

An algorithm based on peripheral CD34+ cells and hemoglobin concentration provides a better optimization of apheresis than the application of a fixed CD34 threshold

BACKGROUND

Optimization of peripheral blood stem cell (PBSC) collection for autologous bone marrow transplantation is necessary for a good standard of care and cost-effectiveness. An algorithm was validated for prediction of the day of maximum peripheral CD34+ cell concentration after mobilization chemotherapy (Day(CD34peak)).

STUDY DESIGN AND METHODS

This study compared mobilization and collection variables of a cohort of patients where apheresis was started at the Day(CD34peak) predicted by the algorithm with a patient group where PBSCs were collected when PB CD34+ cell concentration reached 10 per microL per day (Day(CD34threshold)). Day(CD34peak) was calculated according to the equation Day(CD34peak) = -0.41 x Hb(D0) + 0.99 x Day(CD34threshold) + 7.8 (with Hb(D0) representing the hemoglobin value on Day 0).

RESULTS

The mean number of apheresis procedures per patient based on the Day(CD34threshold) was 1.74, but decreased to 1.35 when applying the new method (Day(CD34peak)). For lymphomas, the mean number of apheresis procedures decreased from 1.98 to 1.47 (p = 0.03), while in patients with multiple myeloma it did not change significantly (1.23 and 1.26, respectively). Age and primary disease influenced the number of apheresis procedures needed to achieve the collection target.

CONCLUSION

The application of our algorithm can lower the number of apheresis procedures by improving the timing, especially in patients suffering from malignant lymphomas with a poor marrow potential after several chemotherapy lines.