Incidence and risk factors of poor mobilization in adult autologous peripheral blood stem cell transplantation: a single-centre experience

Outcomes of patients after mobilization failure of hematopoietic stem cells for autologous stem cell transplantation

INTRODUCTION

Autologous hematopoietic stem cell transplantation (ASCT) is the long-term consolidation treatment for various hematological malignancies. The collection of hematopoietic stem cell yield is critical to successful ASCTs, but not always achieved due to hematopoietic stem cell mobilization failure (HSCMF). Details regarding the cell collection and outcomes of those who fail mobilization are still lacking. Therefore, this study aimed to yield data on clinical outcomes and cellular products after HSCMF.

METHODS

Retrospective, unicentric study assessing clinical outcomes and characteristics of collected progenitor cells. The data were collected from patient databases. The results were reported in median, rates and percentages and absolute values. Patients older than 18 years of age at the time of mobilization and HSCMF were included.

RESULTS

Five hundred ninety-nine patients underwent mobilization protocols. Thirty-five (5.8%) of them failed in the mobilization and fourteen (40%) died. Median time to death was eight months. Disease progression and infection were responsible for all deaths. Median relapse-free survival was 6.5 months (20 patients, 57%). Seven (20%) survivors were receiving salvage therapy and five (14%) were being followed clinically. Six (20.6%) participants underwent collection by apheresis, with insufficient cell collection. The median quantity of peripheral CD34+ cells in those patients was 10.5/mm3. The median CD34+ quantity collected was 0.86 × 106 CD34+ cells/kg.

CONCLUSIONS

The mobilization failure was associated with limited survival. Nonetheless, collected products offered perspectives for ex vivo expansion. Further studies should investigate the feasibility of expanding collected CD34+ cells to use as grafts for ASCT.

Poor Mobilization-Associated Factors in Autologous Hematopoietic Stem Cell Harvest

Peripheral blood stem cell transplantation (PBSCT) is an important therapeutic measure for both hematologic and non-hematologic diseases. For PBSCT to be successful, sufficient CD34+ cells need to be mobilized and harvested. Although risk factors associated with poor mobilization in patients with hematologic diseases have been reported, studies of patients with non-hematologic diseases and those receiving plerixafor are rare. To identify factors associated with poor mobilization, data from autologous PBSC harvest (PBSCH) in 491 patients were retrospectively collected and analyzed. A multivariate analysis revealed that in patients with a hematologic disease, an age older than 60 years (odds ratio [OR] 1.655, 95% confidence interval [CI] 1.049-2.611, p = 0.008), the use of myelotoxic agents (OR 4.384, 95% CI 2.681-7.168, p < 0.001), and a low platelet count (OR 2.106, 95% CI 1.205-3.682, p = 0.009) were associated with poor mobilization. In patients with non-hematologic diseases, a history of radiation on the pelvis/spine was the sole associated factor (OR 12.200, 95% CI 1.934-76.956, p = 0.008). Among the group of patients who received plerixafor, poor mobilization was observed in 19 patients (19/134, 14.2%) and a difference in the mobilization regimen was noted among the good mobilization group. These results show that the risk factors for poor mobilization in patients with non-hematologic diseases and those receiving plerixafor differ from those in patients with hematologic diseases; as such, non-hematologic patients require special consideration to enable successful PBSCH.

On-demand plerixafor added to high-dose cyclophosphamide and pegylated recombinant human granulocyte colony-stimulating factor in the mobilization of patients with multiple myeloma: a treatment with high effectiveness, convenient, and affordable cost

Objective

The combination of high-dose cyclophosphamide (HD-Cy) (3g/m2) plus granulocyte colony-stimulating factor (G-CSF) and on-demand plerixafor (PXF) has been considered an effective mobilization regimen of patients with multiple myeloma(MM). However, the daily multi-injection regimen of G-CSF poses challenges. This study delves into the efficiency and cost implications of a novel approach, using HD-Cy alongside pegylated G-CSF (PEG G-CSF) and on-demand PXF. Unlike G-CSF, which necessitates daily injections, the half-life of PEG G-CSF extended allows for a single injection.

Methods

A retrospective analysis was conducted on 350 MM patients, which were categorized based on their mobilization regimens: Cy+PEG G-CSF+/-PXF (n=66), Cy+PEG G-CSF (n=91), Cy+ G-CSF (n=169), and G-CSF+PXF (n=24).

Results

Mobilization with Cy+PEG G-CSF+/-PXF(8.79)yielded a notably higher median CD34+ cell count compared to the other regimens: Cy+PEG G-CSF(4.96), Cy+G-CSF (4.65), and G-CSF+PXF (2.99) (P<0.001). The percentage of patients who achieved >6×106/kg CD34+ cells was significantly higher in the Cy+PEG G-CSF+/-PXF group (77.3%) than in the other mobilization regimens: Cy+PEG G-CSF (41.8%), Cy+ G-CSF (37.3%), and G-CSF+PXF (8.3%) (P<0.001). From a cost perspective, the Cy+PEG G-CSF+/-PXF approach was more economical than the G-CSF+PXF strategy but was marginally costlier than the other two methods. A multivariate assessment highlighted that the combination of Cy+PEG G-CSF with on-demand PXF had a superior potential to achieve the desired harvest (6×106/kg) compared to the Cy+PEG G-CSF protocol without PXF. The incremental cost-effectiveness ratio for each 1% increase in the probability of achieving a successful optimal harvest was $ 97.02 per patient. The incidence of neutropenic fever was 3.0% in the Cy+PEG G-CSF+/-PXF group.

Conclusion

The combination of on-demand PXF with HD-Cy and PEG G-CSF offers a cost-effective approach with a high mobilization success rate, manageable side effects, and the convenience of fewer injections. It stands as a promising mobilization strategy for MM patients.

Gata2 noncoding genetic variation as a determinant of hematopoietic stem/progenitor cell mobilization efficiency

Germline genetic variants alter the coding and enhancer sequences of GATA2, which encodes a master regulator of hematopoiesis. The conserved murine Gata2 enhancer (+9.5) promotes hematopoietic stem cell (HSC) genesis during embryogenesis. Heterozygosity for a single-nucleotide Ets motif variant in the human enhancer creates a bone marrow failure and acute myeloid leukemia predisposition termed GATA2 deficiency syndrome. The homozygous murine variant attenuates chemotherapy- and transplantation-induced hematopoietic regeneration, hematopoietic stem and progenitor cell (HSPC) response to inflammation, and HSPC mobilization with the therapeutic mobilizer granulocyte colony-stimulating factor (G-CSF). Because a Gata2 +9.5 variant attenuated G-CSF-induced HSPC expansion and mobilization, and HSC transplantation therapies require efficacious mobilization, we tested whether variation affects mechanistically distinct mobilizers or only those operating through select pathways. In addition to affecting G-CSF activity, Gata2 variation compromised IL-8/CXCR2- and VLA-4/VCAM1-induced mobilization. Although the variation did not disrupt HSPC mobilization mediated by plerixafor, which functions through CXCR4/CXCL12, homozygous and heterozygous variation attenuated mobilization efficacy of the clinically used plerixafor/G-CSF combination. The influence of noncoding variation on HSPC mobilization efficacy and function is important clinically because comprehensive noncoding variation is not commonly analyzed in patients. Furthermore, our mobilization-defective system offers unique utility for elucidating fundamental HSPC mechanisms.

Impact of Clinical Parameters and Induction Regimens on Peripheral Blood Stem-Cell Mobilization and Collection in Multiple Myeloma Patients

Introduction

High-dose chemotherapy (HDCT) followed by autologous blood stem-cell transplantation (ABSCT) remains the standard consolidation therapy for newly diagnosed eligible multiple myeloma (MM) patients. As a prerequisite, peripheral blood stem cells (PBSCs) must be mobilized and collected by leukapheresis (LP). Many factors can hamper PBSC mobilization/collection. Here, we provide a comprehensive multiparametric assessment of PBSC mobilization/collection outcome parameters in a large cohort.

Methods

In total, 790 MM patients (471 [60%] male, 319 [40%] female) who underwent PBSC mobilization/collection during first-line treatment were included. Evaluated PBSC mobilization/collection outcome parameters included the prolongation of PBSC mobilization, plerixafor administration, number of LP sessions, and overall PBSC collection goal/result.

Results

741 (94%) patients received cyclophosphamide/adriamycin/dexamethasone (CAD) and granulocyte-colony-stimulating factor (G-CSF) mobilization. Plerixafor was administered in 80 (10%) patients. 489 (62%) patients started LP without delay. 530 (67%) patients reached the PBSC collection goal at the first LP session. The mean overall PBSC collection result was 10.3 (standard deviation [SD] 4.4) × 106 CD34+ cells/kg. In a multiparametric analysis, variables negatively associated with PBSC mobilization/collection outcomes were female gender, age >60 years, an advanced ISS stage, and local radiation pre-/during induction, but not remission status postinduction. Notably, the identified risk factors contributed differently to each PBSC mobilization/collection outcome parameter. In this context, compared to all other induction regimens, lenalidomide-based induction with/without antibodies negatively affected only the number of LP sessions required to reach the collection goal, but no other PBSC mobilization/collection outcome parameters. In contrast, the probability of reaching a high collection goal of ≥6 × 106 CD34+ cells/kg body weight was higher after lenalidomide-based induction compared to VCD/PAD or VAD - taking into account - that a higher G-SCF dosage was given in approximately one-third of patients receiving lenalidomide-based induction with/without antibodies.

Conclusion

Considering the identified risk factors in the clinical setting can contribute to optimized PBSC mobilization/collection. Moreover, our study demonstrates the necessity for a differentiated evaluation of PBSC mobilization/collection outcome parameters.

A novel PEGylated form of granulocyte colony-stimulating factor, mecapegfilgrastim, for peripheral blood stem cell mobilization in patients with hematologic malignancies

BACKGROUND

The Pegylated recombinant human granulocyte colony stimulating factor (PEG-rhG-CSF) has longer half-life and is given once only, which is more comfortable for patients. We aimed to evaluate the efficacy of mecapegfilgrastim for hematopoietic stem cell (HSC) mobilization in patients with hematologic malignancies and to explore the potential factors related to HSC mobilization.

METHODS

A retrospective analysis was performed on patients who underwent HSC mobilization in the hematology department of Mianyang Central Hospital from April 2016 to November 2022. The number of CD34 + cells collected was compared between the patients receiving mecapegfilgrastim (PEG group) and those receiving recombinant human granulocyte colony-stimulating factor (rhG-CSF group), and the possible factors for mobilization failure were analyzed.

RESULTS

The success rates of collecting CD34 + cells in the PEG group and rhG-CSF group were 80.6% and 67.7%, respectively (χ = 1.444, P = 0.229). The median CD34 + cell counts were 3.62 × 10^6/kg and 2.92 × 10^6/kg (P = 0.178), respectively. After combination with plerixafor for mobilization, the median number of CD34 + cells collected in the PEG group and rhG-CSF group were 3.64 × 10^6/kg and 3.92 × 10^6/kg, respectively, with no significant difference (P = 0.754). There was no significant difference in hematopoietic cell recovery or infection between the groups (P > 0.05). Multivariate analysis showed that more than 5 cycles of chemotherapy (OR = 15.897, 95% CI: 1.766-143.127, P = 0.014), a precollection WBC count < 32 × 10^9/L (OR = 14.441, 95% CI: 2.180-95.657, P = 0.006) and a precollection to premobilization lymphocyte ratio < 1.7 (OR = 11.388, 95% CI: 2.129-60.915, P = 0.004) were independent risk factors for HSC mobilization failure.

CONCLUSIONS

The HSC mobilization efficacy of mecapegfilgrastim in patients with hematologic malignancies was comparable to that of rhG-CSF, and combination with plerixafor for mobilization was feasible and effective. Patients with more than 5 cycles of chemotherapy before HSC mobilization, a precollection WBC count lower than 32 × 10^9/L, and a precollection lymphocyte count less than 1.7 times the premobilization lymphocyte count have a high probability of HSC mobilization failure.

Day -1 CD34+ Cells and Platelet Count Predict the Number of Apheresis in Poor-Mobilizer Patients Rescued by Plerixafor

Plerixafor is widely used as up-front treatment with G-CSF to enhance peripheral blood hematopoietic stem cell output in patients failing previous mobilizations. Less frequently, plerixafor is used to rescue an unsatisfactory mobilization following chemotherapy (CT) and G-CSF. This study investigates if pre-collection factors affect the CD34+ cell harvest in chemotherapy and G-CSF mobilizations rescued by plerixafor. Clinical and hematological data relative to patients, mobilization, and apheresis products were retrospectively examined. The outcome was completing a target cell dose ≥ 2 × 10⁶ CD34+ cells/kg at first apheresis. The effect exerted on the outcome by patient- and disease-related factors was investigated by univariate and multivariate logistic regression analysis. The analysis included data from 42 patients affected by hematological (39 patients) and non-hematological malignancies (three patients). Twenty-nine patients (69%) attained the target cell dose at first apheresis. Twelve out of the remaining 13 patients received an additional plerixafor administration, and all accomplished the transplant dose at a second apheresis procedure. Day -1 CD34+ PB count (OR1.46, 95% CI 1.1-1.9, p = 0.008) and platelet count (OR1.0, 95% CI 1.0-1.0, p = 0.033) predicted the achievement of the target dose at first apheresis, independently of pre-mobilization CT, radiation therapy, and disease status at mobilization. At ROC curve analysis, the best cut-off value predicting the successful collection at first apheresis was 7.5/µL for Day -1 CD34+ cell count (AUC 0.830, 0.69 sensitivity, and 0.92 specificity) and 75 × 10⁹/L for Day -1 platelet count (AUC = 0.736, 0.65 sensitivity and 0.85 specificity). In conclusion, on-demand plerixafor rescue allows a successful stem cell collection, irrespectively of disease type and status, prior CT lines, and radiation exposure. Pre-apheresis CD34+ cells and platelet count predict the need for one or two aphereses.

Does myeloma genetic have an effect on stem cell mobilization?

BACKGROUND

Autologous stem cell transplantation (ASCT) after induction treatment is the standard of care. Our understanding of myeloma genetics has been very limited and its effect to stem cell mobilization is not widely investigated. We aimed to investigate the effect of genetic abnormalities on stem cell mobilization in myeloma.

METHODS

The data of 150 MM patients who underwent stem cell mobilization at our center between 2009-2020 were included and analyzed retrospectively. Pre-treatment bone marrow cytogenetics and fluorescence in situ hybridization tests were performed for each patient.

RESULTS

Groups were divided into two as patients with normal cytogenetic and abnormal cytogenetic. No difference observed between groups regarding age, gender and ECOG (p = 0.4; p = 0.2; p = 0.3). Groups were similar concerning myeloma characteristics, received treatment and treatment response. Median CD34+ cells/kg harvested was 444(2-11.29) in normal cytogenetic group whereas it was 4,8(2.4-8.6) in abnormal cytogenetic group(p = 0.2). Optimal CD34+ cells level achievement was 73 (67 %) in normal cytogenetic group while it was 25(71.4 %) in abnormal cytogenetic group(p = 0.6). Neutrophil and platelet engraftment durations were similar among cytogenetic groups (p = 0.7; p = 0.9). R-ISS based groups were also did not differ regarding harvested CD34+ cells and achievement optimal CD34 level (p = 0.79, p = 0.74). Engraftment durations for neutrophil and platelet were comparable between R-ISS based groups (p = 0.59, p = 0.65) CONCLUSIONS: Here we were not able to find any impact of genetic abnormalities on stem cell mobilization in myeloma patients. Expanded studies can aid to identify the effect of particular genetic anomalies on the stem cell mobilization.

Circulatory miR-155 correlation with platelet and neutrophil recovery after autologous hematopoietic stem cell transplantation, a multivariate analysis

The involvement of microRNAs in the regulation of hematopoietic stem cells paves the way for their use in the management of autologous HSC transplantation (AHSCT). We aimed to evaluate the predictive value of circulatory microRNAs in extracellular vesicles (EVs) and plasma in platelet and neutrophil engraftment. Circulatory miR-125b, mir-126, miR-150, and miR-155 expression was assessed in isolated EVs and plasma in samples collected from AHSCT candidates. Multivariate analysis, COX models, and ROC assessment were performed to evaluate the predictive values of these microRNAs in platelet and neutrophil engraftment. miR-155 expression following conditioning with other clinical factors such as chemotherapy courses after diagnosis was the most significant predictors of platelet/neutrophil engraftment. A CD34⁺ cell count ≥ 3.5 × 10⁶/kg combined with miR-155 could be used as an engraftment predictor; however, in cases where the CD34⁺ cell count was < 3.5 × 10⁶/kg, this parameter lost its predictive value for engraftment and could be replaced by miR-155. The correlation between miR-155 and platelet/neutrophil engraftment even with lower numbers of CD34⁺ cells suggests the importance of this microRNA in the prediction of AHSCT outcome. Moreover, miR-155 could be utilized in therapeutic approaches to provide a better outcome for patients undergoing AHSCT.

Presence of Promyelocytes in Peripheral Blood as a Novel Predictor of Optimal Timing for Single-Step Peripheral Blood Stem Cell Collection

BACKGROUND

Because peripheral blood stem cell (PBSC) collection places a burden on the patient and should ideally be completed in a single procedure, a convenient clinical predictive factor is needed.

METHODS

This retrospective study included 72 patients who underwent autologous PBSC collection. A median volume of 3.9 × 10⁶ CD34-positive cells/kg (range: 0.3-47.4 × 10⁶ cells/kg) was collected on the first day. We defined failure as inability to collect 2.0 × 10⁶ cells/kg on the first day. PBSC collection was classified as failed (n = 25, 34.7%) and successful (n = 47, 65.3%), and patient clinical characteristics were analyzed.

RESULTS

The success group had significantly more cases in which a differential white blood cell count in peripheral blood on the day of PBSC collection detected promyelocytes (n = 34 [72.3%] vs. n = 11 [44.0%] in the failure group; P = 0.008). Sixty-two patients underwent autologous PBSC transplantation (median number of transplanted cells, 5.6 × 10⁶/μL; range: 1.60-47.4 × 10⁶ cells/μL). Among transplanted patients, the success and failure groups did not significantly differ in relation to the interval until neutrophil, platelet, or red blood cell engraftment.

CONCLUSION

The presence of promyelocytes in peripheral blood may be a useful indicator of the optimal timing for single-step PBSC collection.

Is absence of CD56 a predictive factor for peripheral blood stem cell mobilization failure in patients with multiple myeloma?

BACKGROUND

CD56 is believed to play a major role in MM pathogenesis with a 70% to 80% expression rate in malignant plasma cells at the time of diagnosis. Our objective in this study was to investigate the relationship between the characteristics of CD56 expression in bone marrow aspiration material at the time of diagnosis and the success of stem cell mobilization in patients diagnosed with MM.

METHODS

This monocenter study included 94 patients who were diagnosed with MM and had a stem cell mobilization procedure for autologous hematopoietic stem cell transplantation. The primary endpoint of the study was to compare the mobilization success between the groups with and without CD56 expression. The secondary endpoint was to identify other factors affecting mobilization failure outside CD56.

RESULTS

At the time of diagnosis, 49 (52.1%) patients had CD56 expression and 45 (47.9%) did not. Mobilization failed in 11 (11.7%) patients. Age, gender, ISS stage and the number of premobilization treatment regimens were not found predictive of mobilization failure. CD56 negativity was 42.2% in the group that had mobilization success and 90.9% in the group that had mobilization failure (P = .001).

CONCLUSIONS

The fact that CD56 residing on the membrane enables interaction between bone marrow cells and ECM and functions as a signal molecule increases sensitivity to the chemotherapy and G-CSF that are used for mobilization. We found that absence of CD56 can be used as a predictive factor for mobilization failure at the time of diagnosis.

CD34+ cell mobilization, blood graft composition, and posttransplant recovery in myeloma patients compared to non-Hodgkin's lymphoma patients: results of the prospective multicenter GOA study

BACKGROUND

Autologous stem cell transplantation is an established treatment option for patients with multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL).

STUDY DESIGN AND METHODS

In this prospective multicenter study, 147 patients with MM were compared with 136 patients with NHL regarding the mobilization and apheresis of blood CD34+ cells, cellular composition of infused blood grafts, posttransplant recovery, and outcome.

RESULTS

Multiple myeloma patients mobilized CD34+ cells more effectively (6.3 × 10⁶ /kg vs. 3.9 × 10⁶ /kg, p = 0.001). The proportion of poor mobilizers (peak blood CD34+ cell count <20 × 10⁶ /L) was higher in NHL patients (15% vs. 3%, p < 0.001). Plerixafor was added to rescue the mobilization failure in 17 MM patients (12%) and in 35 NHL patients (26%; p = 0.002). The infused grafts contained more natural killer (NK) and CD19+ cells in MM patients. Blood platelet and NK-cell counts were higher in MM patients posttransplant. Early treatment-related mortality was low in both groups, but NHL patients had a higher late (>100 days) nonrelapse mortality (NRM; 6% vs. 0%, p = 0.003).

CONCLUSIONS

Non-Hodgkin's lymphoma and MM patients differ in terms of mobilization of CD34+ cells, graft cellular composition, and posttransplant recovery. Thus, the optimal graft characteristics may also be different.

Optimized peripheral blood progenitor cell mobilization for autologous hematopoietic cell transplantation in children with high-risk and refractory malignancies

BACKGROUND

Autologous hematopoietic stem cell transplantation (aHSCT) using hematopoietic progenitor cells (HPCs) has become an important therapeutic modality for patients with high-risk malignancies. Current literature on standardized method for HPC apheresis in children is sparse and failure rate reported as high as 30%.

PATIENTS/METHODS

A retrospective study of 125 pediatric patients with high-risk malignancies undergoing aHSCT in Western Australia between 1997 and 2016 was conducted.

RESULTS

Mobilization was achieved by means of chemotherapy and granulocyte colony-stimulating factor (G-CSF). Patients underwent apheresis the day after CD34⁺ counts reached ≥20/µL and an additional dose of G-CSF. Peripheral arterial and intravenous lines were inserted in pediatric intensive care unit under local anesthetic and/or sedation, omitting the need for general anesthesia as well as facilitating an uninterrupted apheresis flow. Larger apheresis total blood volumes were processed in patients weighing ≤20 kg. The minimal dose of ≥2 × 10⁶ CD34⁺ cells/kg was successfully collected in 98.4% of all patients. The optimal dose of 3-5 × 10⁶ CD34⁺ cells/kg was collected in 96% of patients scheduled for a single aHSCT, 87.5% for tandem, and 100% for triple aHSCT. All HPC collections were completed in one apheresis session. Mobilization after ≤3 chemotherapy cycles and cycles including cyclophosphamide resulted in a significantly higher yield of CD34⁺ cells.

CONCLUSION

Our approach to HPC mobilization by means of chemotherapy and single myeloid growth factor combined with optimal collection timing facilitated by continuous apheresis flow resulted in highly effective HPC harvest in children and adolescents with high-risk cancers.

Results from a multicenter, noninterventional registry study for multiple myeloma patients who received stem cell mobilization regimens with and without plerixafor

Plerixafor plus granulocyte-colony stimulating factor (G-CSF) enhances the mobilization of hematopoietic stem cells (HSCs) for collection and subsequent autologous hematopoietic stem cell transplantation (HSCT) in patients with multiple myeloma (MM). This international, multicenter, noninterventional registry study (NCT01362972), evaluated long-term outcomes for MM patients who received plerixafor versus other mobilization regimens. The comparisons were: G-CSF + plerixafor (G-CSF + P) versus G-CSF-; G-CSF + P versus G-CSF + chemotherapy (G-CSF + C); and G-CSF + P + C versus G-CSF + C. Propensity score matching was used to balance groups. Primary outcome measures were progression free survival (PFS), overall survival (OS), and cumulative incidence of relapse (CIR) after transplantation. After propensity matching, 77 versus 41 patients in the G-CSF + P versus G-CSF cohorts, 129 versus 129 in the G-CSF + P versus G-CSF + C cohorts, and 117 versus 117 in the G-CSF + P + C versus G-CSF + C cohorts were matched, respectively. Propensity score matching resulted in a smaller sample size and imbalances were not completely overcome. For both PFS and OS, the upper limits of the hazard ratio 95% confidence intervals exceeded prespecified boundaries; noninferiority was not demonstrated. CIR rates were higher in the plerixafor cohorts. G-CSF + P remains an option for the mobilization of HSCs in poor mobilizers with MM with no substantial differences in PFS, OS, and CIR in comparison with other regimens.

A retrospective study of autologous stem cell mobilization by G-CSF in combination with chemotherapy in patients with multiple myeloma and lymphoma

Factors affecting peripheral blood hematopoietic stem cell (PBSC) mobilization and collection were investigated in patients with multiple myeloma (MM) and lymphoma who were undergoing chemotherapy. Clinical data from 128 patients, including 53 MM and 75 malignant lymphoma (7 Hodgkin's lymphoma and 68 non-Hodgkin's lymphoma) cases were retrospectively analyzed. Autologous PBSCs were mobilized using granulocyte-colony stimulating factor (G-CSF) during chemotherapy, and collected using a continuous flow cell separation instrument. The yields of CD34+ cells per kilogram of patient body weight <2.0×10⁶/kg, >2.0×10⁶/kg or >5.0×10⁶/kg were defined as a failure, a success or ideal mobilization, respectively. In MM and lymphoma patients, the success rates of CD34+ cell acquisition were 73.6 (39/53) and 58.7% (44/75), the ideal rates were 43.4 (23/53) and 30.7% (23/75), and the failure rates were 26.4 (14/53) and 41.3% (31/75), respectively. Univariate and multivariate statistical analysis revealed that negative factors for PBSC mobilization in patients with MM were lenalidomide treatment, multiple chemotherapies, incomplete disease remission and low-level blood hemoglobin; in patients with lymphoma, the negative factors were the histological disease type, incomplete disease remission, being beyond the first-line of previous chemotherapy, multiple chemotherapies, chemotherapy with the HyperCVAD-B mobilization scheme, high-dose MTX/Ara-c (methotrexate/cytarabine) treatment, prolonged administration of G-CSF and low-hematocrit levels. In the present study, different factors influencing PBSC mobilization and collection in MM and lymphoma cases were identified. PBSC mobilization yielded sufficient CD34+ cell counts both in MM and lymphoma patients; however, the failure rates were relatively high.

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.

Peripheral blood stem cell mobilization failure

Autologous hematopoietic stem cell transplantation (HSCT) is an important and often life saving treatment for many hematological malignancies and selected solid tumors. To rescue hematopoiesis after high-dose chemotherapy in autologous HSCT depends on maintaining sufficient stem cells. Hematopoietic stem cells and progenitor cells expressing CD34 in the BM are mobilized into the circulation with granulocyte-colony stimulating factor ± chemotherapy prior to autologous HSCT. One of the most important factors for success of autologous HSCT is hematopoietic stem cell (HSC) count. Minimum threshold for the engraftment of hematopoietic cells is accepted as 2 × 10(6) CD34 + cells/kg especially for platelet engraftment. Below this level it is defined as stem cell mobilization failure. There are several factors affecting stem cell mobilization: prior chemotherapy (such as fludarabine, melphalan, lenalidomide) and radiotherapy, age, type of disease, bone marrow cellularity. We tried to summarize the reasons of peripheral stem cell mobilization failure.

A novel hematopoietic progenitor cell mobilization and collection algorithm based on preemptive CD34 enumeration

BACKGROUND

The collection of autologous peripheral blood (PB) stem cells can be challenging in the subgroup of patients deemed "poor mobilizers" with granulocyte-colony-stimulating factor. Plerixafor, a CXCR-4 antagonist, is an alternative mobilizing agent, but is costly, and the optimal mobilization algorithm has yet to be determined.

STUDY DESIGN AND METHODS

To address the question we developed a protocol measuring PB CD34 on Day 4 of mobilization. We examined 26 patients before initiating the protocol versus 24 patients after initiation.

RESULTS

Significant differences (p ≤ 0.05) included fewer days of collection (1.25 days vs. 2.42 days), lower total blood volume processed (25.9 L vs. 57.2 L), lower total product volume (324 mL vs. 691 mL), lower RBC content (9 mL vs. 18 mL), and lower granulocyte percentage per collection (35% vs. 11%). There were no significant differences between the two groups in demographics, baseline platelet count, total CD34, or CD34/kg harvested.

CONCLUSION

Use of a protocol to assess PB CD34 1 day before collection allows for preemptive administration of plerixafor to augment mobilization. Subsequently, days of collection and processed blood volume are reduced while there is less RBC and granulocyte contamination in the collected stem cell product.