Evaluation of mobilized CD34+ cell counts to guide timing and yield of large-scale collection by leukapheresis

Feasibility and kinetics of CD34+ hematopoietic progenitor cell mobilization in response to a single administration of docetaxel chemotherapy and pegfilgrastim in a contemporary cohort of patients with metastatic breast cancer

AIM

Autologous hematopoietic stem cell transplantation (auto-HSCT) remains an experimental therapy for metastatic breast cancer (MBC) and there is no established protocol for cluster of differentiation 34⁺ (CD34⁺ ) hematopoietic progenitor cell (HPC) mobilization with historic studies using growth factors with or without chemotherapy. This study describes the feasibility and kinetics of CD34⁺ HPC mobilization following a single administration of docetaxel and the pegylated form of recombinant human granulocyte colony-stimulating factor analogue filgrastim (pegfilgrastim).

METHODS

The study design was serial measurement of peripheral blood CD34⁺ HPC in patients with MBC following a single administration of intravenous (IV) docetaxel 100 mg/m² on day 1 and subcutaneous (SC) pegfilgrastim 6 mg on day 2.

RESULTS

Eight patients with MBC were enrolled. The median age was 56 years (range 51-75 years). All patients had human epidermal growth factor receptor 2 (HER2) negative disease and either hormone refractory or negative disease. Three patients had bone only disease, four had visceral organ disease with or without bone involvement and one had locally unresectable disease only. All patients had prior therapy for early-advanced stage disease and prior therapy for MBC included seven patients receiving at least one line of hormone therapy and three having palliative chemotherapy. Six patients recorded a rise in the CD34⁺ count greater than 20 cells/μL. The median peak level was 40.2 cells/μL (standard deviation = 28.7) occurring on day 9 and with an average duration of 4 days. Overall, treatment was well tolerated with manageable side-effects.

CONCLUSION

The single administration of docetaxel and pegfilgrastim was effective in mobilization of CD34⁺ HPC and peak levels followed a predictable course. This approach needs validation in prospective studies by preparation of auto-HSCT by leukapheresis and quantification of total CD34⁺ HPC yields.

PBSC harvests individually optimized by using pre-collection CD34(+) values and on-line flow cytometric analysis of the mononuclear cell enrichment

BACKGROUND

We have investigated how the amount of blood processed during collection of PBSC affects the yield of CD34 cells.

METHODS

We first established a method of significantly increasing the enrichment of mononuclear cells (MNC), CD34(+) cells and granulocyte-macrophage progenitors (GM-CFU) by on-line flow cytometric (FCM) analysis of the leukocyte populations in the collect line. A total of 166 PBSC collections from 94 patients, were devided into five groups according to the blood volume processed: < 12 L of processed blood, 12-13L, 13-14L, 14-15L and > 15L.

RESULTS

When the yield of CD34(+) cells war compared between these groups, a positive correlation was seen (r=0.97) between the processed blood volume and the yield, expressed as a ratio between total number of CD34(+) cells in the harvest and the CD34(+) cell concentration in blood. This correlation can be used to estimate the volume that must be processed to exceed a specific target number of CD34(+) cells. The implications of these results on the need for one, two or more leukapheresis procedures in order to collect a sufficient amount of stem and progenitor cells for a given patient are discussed, i n relation to clinical logistics and the benefits for the patients.

DISCUSSION

PBSC harvest can be improved by individually-adjusted leukapheresis according to on-line FCM analysis and pre-harvest levels of CD34(+) cells and the processed blood volume can be used to predict the CD34(+) yield.

Priming with r-metHuSCF and filgrastim or chemotherapy and filgrastim in patients with malignant lymphomas: a randomized phase II pilot study of mobilization and engraftment

SCF has been shown to synergize with G-CSF to mobilize CD34(+) PBPCs. In this study we report results from this combination after a phase II trial of 32 patients with malignant lymphoma randomized to receive recombinant methionyl human SCF (ancestim, r-metHuSCF) in combination with recombinant methionyl human G-CSF (filgrastim, r-metHuG-CSF) (experimental arm A) or routine chemotherapy plus filgrastim (conventional arm B). The primary objective was to evaluate the side effects and toxicity during priming and mobilization. The secondary objectives were efficacy by the level of blood-circulating PBPCs, the number of harvest days and the time to three-lineage engraftment after autografting. First, during priming 5 patients had 8 serious events, 4 in each arm. A summary of all adverse events revealed 30 (94%) patients suffering from 132 events of all grading. Second, neutropenia and thrombocytopenia was documented in arm B. Third, 9/14 (64%) patients in arm A reached the target of 5 million CD34(+) cells/kg body weight (bw) compared with 13/15 (87%) in arm B. The results represent the first randomized trial of growth factor plus chemotherapy priming and indicate that a formal phase III trial very unlikely may challenge chemotherapy plus r-metHuG-CSF priming in candidates for high-dose therapy.

Progenitor cell recruitment during individualized high-flow, very-large-volume apheresis for autologous transplantation improves collection efficiency

BACKGROUND

Individual adaptation of processed patient's blood volume (PBV) should reduce number and/or duration of autologous peripheral blood progenitor cell (PBPC) collections.

STUDY DESIGN AND METHODS

The durations of leukapheresis procedures were adapted by means of an interim analysis of harvested CD34+ cells to obtain the intended yield of CD34+ within as few and/or short as possible leukapheresis procedures. Absolute efficiency (AE; CD34+/kg body weight) and relative efficiency (RE; total CD34+ yield of single apheresis/total number of preapheresis CD34+) were calculated, assuming an intraapheresis recruitment if RE was greater than 1, and a yield prediction models for adults was generated.

RESULTS

A total of 196 adults required a total of 266 PBPC collections. The median AE was 7.99 x 10(6), and the median RE was 1.76. The prediction model for AE showed a satisfactory predictive value for preapheresis CD34+ only. The prediction model for RE also showed a low predictive value (R2 = 0.36). Twenty-eight children underwent 44 PBPC collections. The median AE was 12.13 x 10(6), and the median RE was 1.62. Major complications comprised bleeding episodes related to central venous catheters (n = 4) and severe thrombocytopenia of less than 10 x 10(9) per L (n = 16).

CONCLUSION

A CD34+ interim analysis is a suitable tool for individual adaptation of the duration of leukapheresis. During leukapheresis, a substantial recruitment of CD34+ was observed, resulting in a RE of greater than 1 in more than 75 percent of patients. The upper limit of processed PBV showing an intraapheresis CD34+ recruitment is higher than in a standard large-volume leukapheresis. Therefore, a reduction of individually needed PBPC collections by means of a further escalation of the processed PBV seems possible.

Prediction of target CD34 positive cells following leukopheresis in children with neuroblastoma

BACKGROUND

Myeloablative chemotherapy followed by autologous stem cell transplantation (ASCT) may improve long-term survival in children with disseminated neuroblastoma. In children it is important to be able to ascertain when to start the leukopheresis in order to keep the number of procedures to a minimum.

PROCEDURE

Twenty-three children with high-risk neuroblastoma with a median weight of 13 kg (range 8-16 kg). Stem cell collection was planned to start at day 14 after the start of the preceding induction standard chemotherapy and after 4 days of G-CSF treatment at 10 microg/kg body weight once daily subcutaneously. Normal volume leukopheresis (median 2.2 times the blood volume of the child) was carried out using a CS-3000 Plus Blood Cell Separator. A pre-collection peripheral blood CD34+ count of >20/microl was a prerequisite for initiating the stem cell collection.

RESULTS

Timely leukopheresis was carried out in 19/23 patients. In 17 (74%) of the patients the target number of CD34+ cells/kg body weight was obtained in one procedure; in the remaining the target number of stem cells was obtained after leukopheresis on the following day. A highly significant correlation was found between the pre-harvest CD34+ count from the peripheral blood and the total number of collected CD34+ cells/kg (r = 0.79, P < 0.001).

CONCLUSION

When the pre-harvest CD34+ count was >40/microl, a sufficient number of CD34+ stem cells was collected in a single procedure in 15 out of 16 cases.

Comparison of flow cytometry vs. a haematology cell analyser-based method to guide the optimal time-point for peripheral blood stem cell apheresis

BACKGROUND AND OBJECTIVES

For timing the onset of apheresis, parameters obtained by flow cytometry and by a haematological cell analyser were compared.

MATERIALS AND METHODS

Haematopoietic cell counts (n = 159) were performed by two different methods; CD34 analyses by flow cytometry, immature myeloid information (IMI) and human progenitor cell counts (HPC) by a haematological cell analyser.

RESULTS

Comparing the IMI total results with CD34+ analyses (n = 159) revealed a correlation of r = 0.46 (P < 0.05). Similar results were obtained for HPC (r = 0.44; P < 0.05).

CONCLUSION

The haematology analyser-based method does not allow the precise determination of absolute haematopoietic stem cell numbers and is thus not able to replace flow cytometry for the monitoring of peripheral blood stem cell counts.

A phase II study of escalated-dose docetaxel with granulocyte colony-stimulating factor support in patients with advanced breast cancer

PURPOSE

Docetaxel is highly active in the treatment of patients with breast cancer. The principal dose-limiting toxicities of the 3-weekly regimen are neutropenia and febrile neutropenia. In a previous phase I dose-escalation study with granulocyte colony-stimulating factor (G-CSF) support, the recommended dose was determined to be docetaxel 160 mg/m(2) 3-weekly. The objectives of this phase II study were to determine the response rate and toxicity of this dose and schedule, given as first-line in patients with advanced breast cancer. Mobilisation of peripheral blood stem cells (PBSCs) was also investigated.

PATIENTS AND METHODS

Eligible women had metastatic breast cancer and were aged 18-75 years with ECOG performance status < or =2. Strict criteria for liver function were followed, and adjuvant chemotherapy must have been completed at least 6 months previously. Treatment was docetaxel 160 mg/m(2) over 60-90 min every 21 days with G-CSF 5 micro g/kg/day until neutrophil recovery, for up to six cycles. A 3-day corticosteroid prophylaxis was given. Bloods samples to determine PBSC levels [CD34+, granulocyte-macrophage colony-forming cells (GM-CFC) and burst-forming units-erythroid (BFU-E)] were taken on days 6, 8, 9 and 11 following docetaxel.

RESULTS

Twenty-five women with median age 50 years (range 35-66) were included. Seventeen (68%) had previously received adjuvant chemotherapy. In total, 112 cycles were delivered (median four per patient), with dose reductions required in 12.5% of cycles. G-CSF was given for a median of 6 days. The median neutrophil nadir was 0.5 x 10(9)/l and occurred a median 5 days after treatment. The median duration of grade 3 or 4 neutropenia was 2 days (range 1-7). Grade 4 neutropenia occurred in 44% of patients, but there was only one episode of febrile neutropenia. Five patients were taken off study due to toxicities that included oedema, neurosensory toxicity and asthenia. Confirmed partial response was seen in nine patients (37.5%; 95% confidence interval 19% to 59%). CD34+ cells, GM-CFC and BFU-E levels peaked at day 8 following docetaxel administration. The median CD34+ cell peak was 6.5 x 10(4)/ml, with only 20% of patients <2 x 10(4)/ml, a level below which leukapheresis is not usually attempted.

CONCLUSIONS

Docetaxel 160 mg/m(2) was delivered with G-CSF support with a very low rate of febrile neutropenia. Non-haematological toxicity was significant, causing five patients to go off study. Effective mobilisation of PBSCs was seen. The response rate of 37.5% was less than that obtained in first-line studies using standard-dose docetaxel 100 mg/m(2), suggesting that there is no additional benefit in dose escalation of this cytotoxic agent in breast cancer patients using this schedule.

HPC enumeration with the Sysmex XE-2100 can guide further flow cytometric CD34+ measurements and timing of leukaphereses

BACKGROUND

The aim of this study was to evaluate whether HPC counts measured with the hematology analyzer can predict CD34+ levels in peripheral blood and in the apheresis product, as detected by standard flow cytometry. The main focus was the evaluation of HPC counts in poor mobilizers.

METHODS

Progenitor cell quantification was performed measuring HPC counts provided by the Sysmex XE-2100 hematology analyzer and CD34+ counts obtained in parallel by flow cytometry. Peripheral blood of patients who had received chemotherapy and G-CSF (142 measurements) and healthy donors mobilized with G-CSF alone (106 measurements) was investigated HPC counts in peripheral blood were also correlated with apheresis yield.

RESULTS

HPC counts were significantly higher than CD34+ counts (3.5 fold inpatients and 1.7 fold in healthy donors, p= 0.0015). Our data indicate that HPC counts < or = 10/microL in pretreated patients predict a low probability of adequate CD34+ counts in peripheral blood and yields < 2 x 10(6)/kg in subsequent aphereses. Furthermore, repetitive low HPC enumerations in an individual were followed by insufficientCD34+ counts in peripheral blood or aphereses in 81% of investigations. In healthy donors low HPC counts (< or = 10/microL; 12/106 measurements) did not exclusively predict low CD34+ counts (median 23/microL).

DISCUSSION

HPC counts can be used to schedule the start of CD34+ measurements(threshold > 10 HPC/microL) in patients mobilized after chemotherapy for autologous donation. Thus, expensive and time-consuming CD34+ enumerations can perhaps be minimized HPC measurements cannot completely replace flow cytometric CD34+ enumeration. In particular healthy stem-cell donors should be monitored with both methods to exclude false negative HPC measurements.

Change in CD34+ cell concentration during peripheral blood progenitor cell collection: effects on collection efficiency and efficacy

BACKGROUND

An understanding of factors affecting CD34+ cell collection efficacy is essential to minimize donor toxicity and cost.

STUDY DESIGN AND METHODS

Peripheral blood CD34+ cell (CD34) measurements were determined at various intervals before, during, and after automated cell collection (Cobe Spectra 6.0). The serial mean of multiple, intraprocedural CD34 levels was calculated for each procedure as an estimate of the mean, inlet-line CD34 level.

RESULTS

The CD34+ concentration fell a mean of 30 percent in the first 30 to 70 minutes of collection. The degree of decline was inversely correlated with donor blood volume (BV), but was not due to hemodilution. The mean of the CD34 level before and after collection slightly overestimated the serial mean CD34 level. Cell yields, normalized for the CD34 level before collection, were higher from donors with larger BVs.

CONCLUSIONS

The CD34 concentration rapidly decreased to a relative equilibrium level during the collection procedure. The degree of decrease in the CD34 level inversely correlated with the BV of the donor and was consistent with cell pooling in the collection set. The higher equilibrium CD34 levels in donors with larger BVs resulted in increased collection of CD34+ cells, and therefore, large-volume apheresis should be most efficient in these donors.

Assessing agreement between CD34 enumeration by flow cytometry and volumetric analysis

Prior to replacement of an established method for CD34 enumeration by an alternative approach, evaluation of the agreement between the methods is essential. In this study, the comparison of two assays was evaluated according to the recommendation of Bland and Altman describing the agreement between two methods where the true value is not known. CD34 enumeration was performed on blood or leukapheresis product from 105 patients by flow cytometry (dual platform assay) and volumetric analysis (single platform assay). Both the flow cytometric and the volumetric analysis showed poor reproducibility for measures lower than approximately 9 CD34+ cells/mm3. For values higher than 29 CD34+ cells/mm3, evaluation of the agreement demonstrated a difference between the single and dual platform assay, where CD34 enumeration by the volumetric analysis demonstrated values 73-80% of the flow cytometric value. The difference between the two assays could be due to several technical pitfalls which are discussed.

Peripheral blood progenitor cell transplantation

Peripheral blood progenitor cells (PBPCs) have become increasingly popular over the last 15 years as the source of hematopoietic stem cells for transplantation. In the early 1990s, PBPCs replaced bone marrow (BM) as the preferred source of autologous stem cells, and recently the same phenomenon is seen in the allogeneic setting. Under steady-state conditions, the concentration of PBPCs (as defined by CFU-GM and/or CD34+ cells) is very low, and techniques were developed to increase markedly this concentration. Such mobilization techniques include daily injections of filgrastim (G-CSF) or a combination of chemotherapy and growth factors. Leukapheresis procedures allow the collection of large numbers of circulating white blood cells (and PBPCs). One or two leukapheresis procedures are often sufficient to obtain the minimum number of CD34+ cells considered necessary for prompt and consistent engraftment (i.e., 2.5-5.0 x 10(6)/kg). As compared to BM, autologous transplants with PBPCs lead to faster hematologic recovery and have few, if any, disadvantages. In the allogeneic arena, PBPCs also result in faster engraftment, but at a somewhat higher cost of chronic graft-versus-host disease (GvHD). This may be a double-edged sword leading to both increased graft-versus-tumor effects and increased morbidity. The rapid advances in the study of hematopoietic, and even earlier, stem cells will continue to shape the future of PBPC transplantation.

Clinical practice and future needs in recombinant human granulocyte colony-stimulating factor treatment: a review of randomized trials in clinical haemato-oncology

Recombinant human granulocyte colony-stimulating factor (rHuG-CSF) may have a significant impact on preventing infections associated with chemotherapy-induced neutropenia, as well as shortening time to tree lineage engraftment following high-dose chemotherapy and progenitor transplantation. However, the scientific literature documenting evidence-based practice is insufficient and often misinterpreted. This review presents data and discusses the evidence for actual clinical practice in the use of rHuG-CSF in conventional cyclic chemotherapy, either prophylactic or therapeutic, and high-dose therapy, either in priming for mobilization or post-transplantation. In the past decade, many reports have based their conclusions on surrogate markers, and it is time to move towards evaluation of clinically relevant factors. Data must be generated prospectively based on current clinical practice, and several issues must be considered and evaluated to define the true clinical benefit of rHuG-CSF with or without stem-cell support. Evaluation should include complications and needs for resources as well as impact on toxicity and efficacy of conventional or high-dose chemotherapy.

A European reference protocol for quality assessment and clinical validation of autologous haematopoietic blood progenitor and stem cell grafts

Recently, the regulatory authorities have begun to show interest in haematopoietic stem cell products. On a professional rather than a regulatory basis, the International Society for Hematotherapy and Graft Engineering (ISHAGE) has established the Foundation for the Accreditation of Haematopoietic Cell Therapy (FACHT), which has drawn up guidelines for standards and accreditation of such activity. In Europe, the regulatory environment with regard to haematopoietic stem cell grafts, processing and storage are currently less stringent. However, in 1998 the European Joint Accreditation Committee Euro-ISHAGE/EBMT (JACIE) prepared a regulatory document 'Standards for Blood and Marrow Progenitor Cell Collection, Processing and Transplantation' which was approved by the EBMT General Assembly. The major objectives were to promote quality of medical and laboratory practice in haematopoietic progenitor cell transplantation. The standards extend and detail the pre-existing activity of EBMT centres including all phases of collection, processing and administration of these cells. This is the platform for the proposed reference protocol for CD34(+) cell enumeration and clinical validation of quality assessment to ensure that appropriate standards of work and product quality are established and will be maintained.

Cytofluorometric methods for assessing absolute numbers of cell subsets in blood. European Working Group on Clinical Cell Analysis

The enumeration of absolute levels of cells and their subsets in clinical samples is of primary importance in human immunodeficiency virus (HIV)+ individuals (CD4+ T- lymphocyte enumeration), in patients who are candidates for autotransplantation (CD34+ hematopoietic progenitor cells), and in evaluating leukoreduced blood products (residual white blood cells). These measurements share a number of technical options, namely, single- or multiple-color cell staining and logical gating strategies. These can be accomplished using single- or dual-platform counting technologies employing cytometric methods. Dual-platform counting technologies couple the percentage of positive cell subsets obtained by cytometry and the absolute cell count obtained by automated hematology analyzers to derive the absolute value of such subsets. Despite having many conceptual and technical limitations, this approach is traditionally considered as the reference method for absolute cell count enumeration. As a result, the development of single-platform technologies has recently attracted attention with several different technical approaches now being readily available. These single-platform approaches have less sources of variability. A number of reports clearly demonstrate that they provide better coefficients of variation (CVs) in multicenter studies and a lower chance to generate aberrant results. These methods are therefore candidates for the new gold standard for absolute cell assessments. The currently available technical options are discussed in this review together with the results of some cross-comparative studies. Each analytical system has its own specific requirements as far as the dispensing precision steps are concerned. The importance of precision reverse pipetting is emphasized. Issues still under development include the establishment of the critical error ranges, which are different in each test setting, and the applicability of simplified low-cost techniques to be used in countries with limited resources.

Stem Cell Collection using the Dideco Excel Continuous Flow Blood Cell Separator: Parameters for Optimal Stem Cell Collection Timing

This study evaluates stem cell collection procedures performed with the Dideco Excel blood cell separator, with particular attention given to yields and separator collection efficiencies. Patients’ blood precounts and yield parameters related to the harvest capacity of the collection system were investigated. Fifty-five collection procedures were analyzed in 32 patients suffering from hematological malignancies and solid tumors and mobilized with chemotherapy plus G-CSF. The median blood volume processed in each procedure was 15.8 liters (12–19.750), with a blood flow rate of 70 ml/min. Patients had the following median blood precount value: NC 7.81×109/L, CD34+ cells 49.08×103/ml. Leukapheresis procedures gave the following yields: NC 14.95×109, MNC 10.83×109, CD34+ cells 4.37×106; yields/kg, NC 0.21×109kg, MNC 0.15×109/kg CD34+ cells 4.26×106/kg. Procedures show the following collection efficiencies: NC 10.79%, MNC 29.06%, CD34+ 42.33%, PLT 26.5%. The RBC (red blood cell) contamination of the product was (median value) 20.9 ml for each procedure, and for platelets 1.76×1011 per procedure. The CD34+ cell precounts strongly correlated with the CD34+ yields/kg (r=0.82. p=0.000). Furthermore the NC and MNC precounts correlated with the CD34+ yields/kg but only the MNC precount correlation is notable (r=0.57, p=0.000). The logistic regression analysis shows that CD34+ (p=0.008) but not NC (po=0.14), MNC (p=0.09), or PLT (p=0.53) precounts significantly influenced the collection of a sufficient dose of CD34+ cells for transplantation (≥ 2.5×106/kg). Eleven of the thirty-two patients have been transplanted till now, and all had a prompt and lasting trilineage engraftment NC >1×109/L on day 12 (10–17). Our data show that the collection system analyzed in this report is able to collect large amounts of progenitor cells, harvesting ≥2.5×106/kg CD34+ cells with a single procedure in 68.8% of patients and assuring complete recovery after stem cell transplantation.

Technical aspects and clinical impact of hematopoietic progenitor subset quantification

As high-dose therapy for malignancies is now being applied to newly diagnosed patients as adjuvant therapy, it has become a requirement that quality and safety assessment of hematopoietic stem cell grafts be evidence-based. This process has developed a new institution in medicine, the stem cell laboratory. In most cases this speciality has evolved from or within hematological research laboratories. However, the increased routine technologies applied in quality evaluation, ex vivo manipulation and safety assessment in stem cell handling naturally places this activity in transfusion medicine. Multiparametric flow cytometry can identify progenitor subsets in normal human bone marrow and peripheral blood, and such subset quantification has been used retrospectively to predict three-lineage engraftment following high-dose therapy for malignancies. Published single center data have suggested an impact on clinical outcome, and a standardized technique for subset enumeration needs to be established before prospective multicenter trials can be initiated to document the prognostic value of such quality assessment in autografting. Based on experiences of CD34 enumeration, which we consider to be the first step in quality assessment of hematopoietic stem cell grafts, this review discusses flow cytometry subset identification by lineage-specific differentiation markers, stromal-dependent adherence molecules, and regulatory growth factor receptors from a technical point of view. The aim of this review is:To recommend a simple method based on the experiences of the Nordic workshop III on subset identification; To present new molecular genetic-based methods for future use in quality assessment; and To propose new endpoints necessary for validation of the likely clinical impact of subsets in prospective trials. As sample differences between blood and marrow result in technical difficulties, this review only focuses on the methodology of identifying subsets in blood and leukapheresis products. Methods for subset analysis in diagnostic bone marrow samples will be covered in a forthcoming review.

Enhancement of the anti-tumor activity of a peripheral blood progenitor cell graft by mobilization with interleukin 2 plus granulocyte colony-stimulating factor in patients with advanced breast cancer

OBJECTIVE

Autologous interleukin 2 (IL-2)-activated natural killer (NK) cells kill a broad spectrum of tumor targets, including breast cancer. We hypothesized that mobilization with IL-2 and granulocyte colony-stimulating factor (G-CSF) for collection of peripheral blood progenitor cells (PBPC) may enhance the anti-tumor activity of the graft in autograft recipients. We determined the dose-limiting toxicity and maximum tolerated dose of subcutaneous IL-2 given with G-CSF for PBPC mobilization, the ability of IL-2 + G-CSF mobilized stem cells to reconstitute hematopoiesis, and the in vitro immunologic function of the graft in patients with advanced breast cancer. MATERIALS AID METHODS: Forty-three women with stage IIIA/B or metastatic breast cancer underwent mobilization of PBPC with IL-2 administered subcutaneously for 14 days along with G-CSF for the latter 7 days. IL-2 was given in a dose-escalated manner, with the maximum tolerated dose determined to be 1.75 x 10(6) IU/m(2)/day. Fifteen women with stage IIIA/B or metastatic breast cancer underwent G-CSF mobilization alone and served as a control group.

RESULTS

[corrected] Fifty-two percent of the patients mobilized with 1L-2 at the maximum tolerated dose reached the target number of CD34(+) cells for transplantation with three aphereses compared to 93% of control patients who were mobilized with G-CSF alone. [corrected] There was no significant impact on time to engraftment of neutrophils or platelets using either mobilization regimen. The addition of subcutaneous IL-2 to mobilization increased the cytotoxicity of IL-2-activated mononuclear cells from the PBPC product against the breast cancer cell target, MCF-7, and increased the percentage of NK cells and activated T cells in the PBPC product. The enhanced NK cell number was sustained in the early posttransplant period.

CONCLUSIONS

[corrected] IL-2 + G-CSF mobilization is safe, may lead to a more immunologically functional graft without impairing hematologic recovery, and thus merits further exploration to evaluate the clinical anti-tumor efficacy of these immunocompetent grafts. [corrected] Limitations of this combined approach to stem cell mobilization include a decrease in the number of CD34(+) cells mobilized with the combined cytokines and the short duration of the increased number of anti-tumor effector cells after transplant.

Toward standardization of CD34+ cell enumeration: an international study. Biomedial Excellence for Safer Transfusion Working Party

BACKGROUND

An international multicenter study, involving six sites in North America and six sites in Europe, was undertaken to assess the performance of standardized methods for the enumeration of CD34+ cells in peripheral blood over the dynamic range from 200 cells per microL to zero. Two commercially available techniques were studied, a flow cytometry method and a microvolume fluorimetry method.

STUDY DESIGN AND METHODS

Coded samples were centrally prepared and sent to test sites by overnight mail. Samples included internal replicates, linear dilutions, and specimens at the lower limit of detection. In addition, commercially available reagent positive control cells were sent to a subset of laboratories.

RESULTS

Over the sample range studied, the intersite precision among different laboratories was good with coefficients of variation ranging from 14 percent to 24 percent for microvolume fluorimetry and from 20 percent to 31 percent for flow cytometry. Intrasite precision ranged from 7 percent to 21 percent. Test linearity was excellent with sites demonstrating a mean r2 = 0.992 for microvolume fluorimetry and r2 = 0.984 for flow cytometry. The lower limit of detection was 5 CD34+ cells per microL for both commercial assays. Over the range of 5 to 50 CD34+ cells per microL, the microvolume fluorimetry assay reported slightly higher values than the flow cytometry assay. Preliminary analysis of reagent positive control cells showed very good precision and accuracy.

CONCLUSIONS

Standardization of CD34+ cells enumeration is improving and commercially available assays provide accurate and precise methods. More investigation of reagent positive control cells is warranted.

Endogenous Interleukin-8 (IL-8) Surge in Granulocyte Colony-Stimulating Factor–Induced Peripheral Blood Stem Cell Mobilization

The relationship between stem cell mobilization with granulocyte colony-stimulating factor (G-CSF) and the endogenous production of interleukin-8 (IL-8), macrophage inflammatory protein-1 (MIP-1), tumor necrosis factor- (TNF-), and interferon-γ (IFN-γ) was studied in normal donors for allogeneic peripheral blood stem cell (PBSC) transplantation. G-CSF was administered to 20 normal donors at a dose of 10 μg/kg/d for 5 days with aphereses on days 5 and 6 of G-CSF treatment. Cytokine serum levels were measured using an enzyme-linked immunosorbent assay (ELISA) before and during G-CSF treatment. Before treatment, the average level of IL-8 was 7.1 pg/mL, increasing to 207.0 pg/mL on day 5 and 189.1 pg/mL on day 6. Serum IL-8 levels correlated CD34+ cell numbers (P = .0151 and P = .0005 on days 5 and 6, respectively) and colony-forming unit–granulocyte-macrophage (CFU-GM) numbers (P = .0019 andP = .0010 on days 5 and 6, respectively). Furthermore, preapheresis serum IL-8 levels correlated with the yield of CD34+ cells (P = .0027). In contrast, before treatment, the average levels of MIP-1, TNF-, and IFN-γ were 70.1, 4.03, and 3.84 pg/mL, respectively, and no significant changes in the levels of these cytokines were observed during G-CSF treatment. These studies suggest that IL-8 production may be critical to G-CSF–induced stem cell mobilization, although the underlying mechanism could not be clarified.

Endogenous Interleukin-8 (IL-8) Surge in Granulocyte Colony-Stimulating Factor–Induced Peripheral Blood Stem Cell Mobilization

The relationship between stem cell mobilization with granulocyte colony-stimulating factor (G-CSF) and the endogenous production of interleukin-8 (IL-8), macrophage inflammatory protein-1 (MIP-1), tumor necrosis factor- (TNF-), and interferon-γ (IFN-γ) was studied in normal donors for allogeneic peripheral blood stem cell (PBSC) transplantation. G-CSF was administered to 20 normal donors at a dose of 10 μg/kg/d for 5 days with aphereses on days 5 and 6 of G-CSF treatment. Cytokine serum levels were measured using an enzyme-linked immunosorbent assay (ELISA) before and during G-CSF treatment. Before treatment, the average level of IL-8 was 7.1 pg/mL, increasing to 207.0 pg/mL on day 5 and 189.1 pg/mL on day 6. Serum IL-8 levels correlated CD34+ cell numbers (P = .0151 and P = .0005 on days 5 and 6, respectively) and colony-forming unit–granulocyte-macrophage (CFU-GM) numbers (P = .0019 andP = .0010 on days 5 and 6, respectively). Furthermore, preapheresis serum IL-8 levels correlated with the yield of CD34+ cells (P = .0027). In contrast, before treatment, the average levels of MIP-1, TNF-, and IFN-γ were 70.1, 4.03, and 3.84 pg/mL, respectively, and no significant changes in the levels of these cytokines were observed during G-CSF treatment. These studies suggest that IL-8 production may be critical to G-CSF–induced stem cell mobilization, although the underlying mechanism could not be clarified.