Timing of peripheral blood stem cell yield: comparison of alternative methods with the classic method for CD34+ cell determination

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.

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.

Correlation of various methods of hematopoietic progenitor cell estimation with standard flowcytometric CD34 enumeration

BACKGROUND AND OBJECTIVES

Enumeration of hematopoietic progenitor cell (HPC) is vital to decide the time to initiate harvest (TTIH) and adequacy of harvest dose (AOHD). Standard of care used for HPC enumeration is flowcytometric CD34+ enumeration, but it is expensive, time-consuming and requires skilled staff to perform the test. Alternatively, HPC-count by advanced automated cell analyzer is cheaper, quicker, and easy-to-perform test. Our objective was to find a correlation of HPC count with CD34+ enumeration in leukapheresis.

MATERIALS AND METHODS

An observational, prospective study was conducted in the year 2018-2019. A total of 126 samples were included in the study, the peripheral blood (PB) group comprised of 42samples and apheresis group of 84 samples. The samples were simultaneously tested for CD34+ expression and complete blood count which included the HPC count, white blood cells (WBC) count and multinational corporation (MNC) count and correlation analysis was performed with CD34+ flowcytometric count. The cut-off of PB HPC count for the target dose of 5 × 106 CD34+ cells/kg was established using Receiver Operator Curve.

RESULTS

The correlation coefficient (r) of HPC with CD34+ count was 0.617 and 0.699 for PB group and apheresis group sample respectively, which was statistically significant. The correlation with MNC and WBC count was not very significant. A cut-off value of PB HPC was established to be 66 HPC/μl with a positive predictive value of 94.12%. The cost of CD34 + flow cytometric enumeration was six times that of HPC enumeration by analyzer.

CONCLUSION

The HPC count is a cheaper, rapid and easy test and can be clinically applied to predict TTIH and AOHD but requires more studies to validate its efficacy in clinical use.

High D-index during mobilization predicts poor mobilization of CD34+ cells after anti-lymphoma salvage chemotherapy

BACKGROUND

Performing stem cell collection after mobilization chemotherapy was a well-balanced strategy between anti-tumor effect and efficient collection of CD34+ cells, but deep and prolonged nadir exposed patients to risk of febrile neutropenia. Febrile neutropenia was known to be associated with lower yields of CD34+ cells, but quantitative data referring to association between yields of CD34+ cells and severity of neutropenia was lacking. We hypothesized that D-index, which was developed for quantitative evaluation of severity of neutropenia especially in the field of hematologic malignancies, could predict yields of CD34+ cells.

METHODS

We performed a single center, retrospective analysis of patients with relapsed or refractory aggressive lymphoma who were mobilized with ESHAP or modified ESHAP. We evaluated the association between yields of CD34+ cells at first apheresis and D-index.

RESULTS

Thirty-six patients were included, and we demonstrated that yields of CD34+ cells from patients with higher D-index were significantly lower than those from patients with lower D-index. Multivariate linear regression analysis and logistic regression analysis also demonstrated the significant predictive power of D-index. Further, D-index was significantly correlated to platelet count before starting mobilization chemotherapy. Platelet count was known to predict yields of CD34+ cells, and combination of platelet count and D-index could identify patients with lowest CD34+ yields.

CONCLUSION

D-index could predict yields of CD34+ cells and it seemed that its predictive power was not less than that of platelet count. Prospective studies including more heterogeneous patients were needed to validate our study.

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.

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.

Assessment of haematopoietic progenitor cell counting with the Sysmex® XN-1000 to guide timing of apheresis of peripheral blood stem cells

BACKGROUND

Successful peripheral blood stem cell (PBSC) collection depends on optimal timing of apheresis, as usually determined by flow cytometry CD34-positive (⁺) cell count in peripheral blood (PB). Since this method is costly and labour-intensive, we evaluated the use of the Hematopoietic Progenitor Cell count programme on a Sysmex^® XN haematologic analyser (XN-HPC) as a rapid and inexpensive alternative for predicting CD34⁺ cell count in PB samples.

MATERIALS AND METHODS

Haematopoietic progenitor cell and CD34⁺ cell counts were compared using 273 PB samples collected from 78 healthy donors and 72 patients who underwent PBSC transplantation. We assessed the effectiveness of the XN-HPC in safely predicting pre-harvest CD34⁺ counts. The most efficient cut-off values of XNHPC were identified. We also evaluated the imprecision (coefficient of variation, CV) and functional sensitivity.

RESULTS

Imprecision of the XN-HPC count was <6.3% on daily measurement of three levels of quality control material. Functional sensitivity was 8.9×10⁶/L. A cut-off value of ≥62×10⁶/L XN-HPC for multiple myeloma (MM) patients and ≥30×10⁶/L for all other subjects had both 100% specificity and 100% positive predictive value for identifying samples with CD34⁺ cells ≥20×10⁶/L. An XN-HPC threshold of <13×10⁶/L identified preharvest CD34⁺ cell count <10×10⁶/L with 100% sensitivity and 100% negative predictive value.

DISCUSSION

The XN-HPC is a fast, easy and inexpensive test that can safely improve apheresis workflow thus possibly replacing other more expensive CD34 counts currently performed and promoting optimal timing of PBSC collection.

Method comparison study of peripheral blood CD34+ count performed on an Abbott CELL-DYN Sapphire hematology analyzer versus flow cytometry reference procedure (modified ISHAGE)

Introduction

CD34+ cell enumeration is a critical parameter used to determine the timing of apheresis collections of hematopoietic progenitor cell products (HPC(A)). Automated hematology analyzers equipped with flow cytometry capabilities may be a solution to the problem of limited access to standard flow cytometry testing.

Methods

We compared CD34+ cell enumeration using a reference flow cytometry procedure employing modified International Society of Hematotherapy and Graft Engineering (ISHAGE) analysis with a hematology analyzer /flow cytometer hybrid (CELL DYN (CD)Sapphire) using a sequential gating analysis designed to emulate the ISHAGE gating strategy.

Results

CD34+ cell values obtained from the ISHAGE and CD Sapphire analysis were plotted and compared in a linear regression analysis which showed a high degree of correlation (R²=0.96). No statistically significant (p=0.53) differences in CD34+ cell enumeration values were observed between the flow cytometer and automated hematology analyzer using manual analysis schema.

Conclusions

We have demonstrated that an automated hematology analyzer equipped with a flow module can provide CD34+ cell enumeration results in the peripheral blood for clinical decision algorithms without the need for a dedicated flow cytometry laboratory.

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.