Large-volume leukapheresis for collection of mononuclear cells for hematopoietic rescue in Hodgkin's disease

Increased mobilization and yield of stem cells using plerixafor in combination with granulocyte-colony stimulating factor for the treatment of non-Hodgkin's lymphoma and multiple myeloma

Multiple myeloma and non-Hodgkin’s lymphoma remain the most common indications for high-dose chemotherapy and autologous peripheral blood stem cell rescue. While a CD34+ cell dose of 1 × 10⁶/kg is considered the minimum required for engraftment, higher CD34+ doses correlate with improved outcome. Numerous studies, however, support targeting a minimum CD34+ cell dose of 2.0 × 10⁶/kg, and an “optimal” dose of 4 to 6 × 10⁶/kg for a single transplant. Unfortunately, up to 40% of patients fail to mobilize an optimal CD34+ cell dose using myeloid growth factors alone. Plerixafor is a novel reversible inhibitor of CXCR4 that significantly increases the mobilization and collection of higher numbers of hematopoietic progenitor cells. Two randomized multi-center clinical trials in patients with non-Hodgkin’s lymphoma and multiple myeloma have demonstrated that the addition of plerixafor to granulocyte-colony stimulating factor increases the mobilization and yield of CD34+ cells in fewer apheresis days, which results in durable engraftment. This review summarizes the pharmacology and evidence for the clinical efficacy of plerixafor in mobilizing hematopoietic stem and progenitor cells, and discusses potential ways to utilize plerixafor in a cost-effective manner in patients with these diseases.

Mobilization strategies for the collection of peripheral blood progenitor cells: Results from a pilot study of delayed addition G-CSF following chemotherapy and review of the literature

OBJECTIVE

Given the potential to limit cost, we conducted a pilot study evaluating delayed, low-dose granulocyte colony-stimulating factor (G-CSF) following chemotherapy for the procurement of peripheral blood progenitor cells (PBPCs) for autologous transplantation and reviewed the relevant literature.

PATIENTS AND METHODS

Twenty-eight patients with various malignancies received cyclophosphamide 4 gm/m(2) and paclitaxel 170 mg/m2 followed by G-CSF 300 microg/d or 480 microg/d starting day +5 until two to four daily large volume leukapheresis yielded > or =5.0 x 10(6) CD34+ cells. We searched MEDLINE, Pubmed, and EMBASE databases from 1990 to the present to identify papers on PBPC procurement using delayed G-CSF (starting day +4 or later) following chemotherapy.

RESULTS

G-CSF was administered for a median of 9 days at an average cost of 1260 USD per 70-kg patient. Collection was initiated at a median of 12 days after chemotherapy. A median 2.5 (range 2-4) apheresis were performed yielding an average daily CD34+ collection of 6.9 x 10(6)/kg (range 0.35-56.7). After one apheresis, 82% and 57% of patients collected > or =2.5 x 10(6)/kg and > or =5.0 x 10(6)/kg, respectively. Ultimately, 89% collected > or =5.0 x 10(6)/kg. Febrile neutropenia and catheter-related infection developed in five and two patients, respectively. All patients proceeded to transplantation and engrafted successfully with a median of 14.9 x 10(6)/kg (range 1.05-113) cells infused. Eleven published reports were identified involving 590 patients of whom 498 received G-CSF at a dose range of 250 microg/d to 10 microg/kg/d starting day +4 to 15 for a period of 4 to 9 days for PBPC procurement. Among these reports, 62 to 100% and 33 to 96% of patients collected > or =2 to 2.5 x 10(6) and > or =5.0 x 10(6) CD34+ cells, respectively.

CONCLUSION

The use of delayed, low-dose G-CSF plus chemotherapy for stem cell mobilization was feasible and provides further evidence supporting this potentially cost-effective strategy. A review of the literature supports our findings and emphasizes the need for larger studies to address this issue.

Peripheral blood hematopoietic stem cells: Biology, apheresis collection and cryopreservation

Introduction Hematopoiesis is a continuous, dynamic and highly complex process resulting in production of various mature blood cells from a small population of pluripotent stem and progenitor cells through diverse proliferative and differentiative events. Numerous studies have demonstrated that a complex network of interactive cytokines regulates the survival, maturation, and proliferation of hematopoietic stem and progenitor cells (HSPCs). Application of cell-mediated therapy Massive application of different cell-mediated therapeutic methods has resulted in an increased need for both specific HSPCs and operating procedures providing minimal cell damage during collection, processing and storage in a liquid or frozen state. Therefore, the basic aim of cell harvesting, selection, as well as cryopreservation is to minimize cell damage during these procedures. HSPCs are cells which exhibit extensive self-renewal and proliferative capacity, associated with the capacity to differentiate into all blood cells and other cell lineages (plasticity of HSPC). Thanks to these properties, stem cells can provide complete and permanent restoration of hematopoiesis, which is the basis for clinical employment of HSPC transplantation. In addition, totipotent stem cells can be used for the so called "cell-therapy" in different clinical settings (e.g. myocardial regeneration after acute infarction). Conclusion Despite the fact that HSPC transplantation is already in routine use, some questions related to the optimal blood progenitor/cell collection, selection, storage and clinical use are still unresolved. Therefore, this review only briefly discusses the therapeutic use of HSPCs in different clinical areas and focuses on the recommendations, as well as the specific transfusion policies related to HSPC collection, processing, and cryopreservation with an emphasis on quality control.

The impact of male-to-male sexual experience on risk profiles of blood donors

BACKGROUND

Men who have had sex with men (MSM) since 1977 are permanently deferred from donating blood. Excluding only men who engaged in male-to-male sex within either the prior 12 months or 5 years has been proposed. Little is known about infectious disease risks of MSM who donate blood.

STUDY DESIGN AND METHODS

Weighted analyses of data from an anonymous mail survey of blood donors were conducted to examine the characteristics of men reporting male-to-male sex during specified time periods.

RESULTS

Of the 25,168 male respondents, 569 (2.4%) reported male-to-male sex, 280 (1.2%) since 1977. Compared to donors who did not report male-to-male sex, the prevalence of reactive screening test results was higher among donors who reported the practice within the past 5 years (< or =12 months odds ratio [OR] 5.3, 95% confidence interval [CI] 2.6-10.4; >12 months to 5 years, OR 7.1, 95% CI 1.2-41.7); however, no significant difference was found for donors who last practiced male-to-male sex more than 5 years ago (>5 years-after 1977, OR 1.4, 95% CI 0.7-2.6; 1977 or earlier, OR 1.6, 95% CI 0.7-3.7). The prevalence of unreported deferrable risks (UDRs) other than male-to-male sex was significantly higher for all donors who reported male-to-male sex with ORs ranging from 3.1 to 18.9 (p < or = 0.01).

CONCLUSIONS

No evidence was found to support changing current policy to permit donations from men who practiced male-to-male sex within the past 5 years. For donors with a more remote history of male-to-male sex, the findings were equivocal. A better understanding of the association between male-to-male sex and other UDRs appears needed.

Large-volume leukapheresis yields more viable CD34+ cells and colony-forming units than normal-volume leukapheresis, especially in patients who mobilize low numbers of CD34+ cells

BACKGROUND

Large-volume leukapheresis (LVL) differs from normal-volume leukapheresis (NVL) by increased blood flow and altered anticoagulation regimen. LVL is now regarded as a safe procedure for collection of peripheral blood progenitor cells (PBPCs), but it is not known whether the procedure will alter CD34+ cell quality or will be useful for patients who mobilize few CD34+ cells into peripheral blood.

STUDY DESIGN AND METHODS

The results from 82 LVL and 125 NVL (4.0-5.3 and 2.7-3.5 times the patients' blood volumes processed, respectively) were retrospectively analyzed in altogether 112 consecutive patients with malignant diseases.

RESULTS

The LVL yielded significantly more CD34+ cells (4.2 x 10(6) vs. 3.1 x 10(6)/kg, p = 0.006, all patients; and 1.8 x 10(6) vs. 1.3 x 10(6)/kg, p = 0.004, bad mobilizers) and significantly higher colony-forming units (77 x 10(4) vs. 33 x 10(4)/kg; all patients and 33 x 10(4) vs. 20 x 10(4)/kg, p < 0.001, both groups). Significantly fewer leukapheresis procedures were required to obtain 2 x 10(6) CD34+ cells per kg (one vs. two, p = 0.001, all patients; and two vs. three, p = 0.009, bad mobilizers). No significant differences in CD34+ cell viability and time to hematologic recovery were observed between the patients who received PBPCs harvested by NVL and LVL.

CONCLUSION

Although a median platelet loss of 36 percent can be expected, LVL can be recommended as the standard apheresis method for PBPC collections in patients with malignant diseases. LVL is particularly useful in patients who mobilize a low number of CD34+ cells into the peripheral blood.

The whys and hows of hematopoietic progenitor and stem cell mobilization

Intentional mobilization of hematopoietic/stem cells into the circulation has improved the efficiency of their collection. Transplantation of mobilized blood stem cells to patients with marrow aplasia results in a faster pace of hematopoietic recovery than transplantation of marrow-derived stem cells. Autologous and allogeneic hematopoietic stem cell transplantation are increasingly performed with blood-derived cells. Donors of both autologous and allogeneic blood stem cells do not always respond well to therapies designed to produce mobilization. Autologous donors may respond poorly as a result of myelotoxic damage inflicted by prior antitumor therapy, but this explanation is not valid for allogeneic donors. The mechanism(s) involved in the process of mobilization are incompletely understood. Until these mechanisms are elucidated, methods to improve mobilization vigor on a rational basis will not be obvious. In the meanwhile, clinical observations may provide some hints regarding the whys and hows of mobilization and permit incremental improvements in this process.

Prospective, randomized, sequential, crossover trial of large-volume vs. normal-volume leukapheresis procedures: effects on subpopulations of CD34(+) cells

Some data exist on the influence of leukapheresis volume on the number of harvested peripheral blood hematopoietic progenitor cells (HPC), but less is known about the influence on the composition of HPC. We therefore performed a prospective, randomized crossover trial to evaluate the effect of large-volume (LVL) vs. normal-volume leukapheresis (NVL) on subpopulations of CD34(+) cells in the harvest product of 15 patients with breast cancer and 8 patients with non-Hodgkin's lymphoma. Patients were randomly assigned to start either with an LVL on day 1 followed by an NVL on day 2 or vice versa. The number of HPC, the extraction efficiency defined as difference between yield in the harvest and decrease in peripheral blood, and the relative proportion as well as the absolute numbers of CD34(+) cells coexpressing CD38, CD90, HLA-DR, CD117, CD7, CD19, CD41, or CD33 were evaluated. There was no significant difference with regard to the percentages of the subsets on comparison of LVL to NVL procedures. Only the absolute median number of CD34(+)HLA-DR(-) cells was significantly (P=0.02) higher in LVL harvests compared with the corresponding NVL components, which can be explained on the basis of the higher yield and the higher extraction efficiency in LVL compared with NVL. LVL results in a higher yield of CD34(+) cells and leads to an intra-apheresis recruitment of HPC but the relative composition of the harvested CD34(+) cells is not changed significantly. In addition, the amount of early, HLA-DR(-), hematopoietic HPC seems to be increased by an LVL.

Trafficking of CD34+ cells into the peripheral circulation during collection of peripheral blood stem cells by apheresis

The number of CD34+ cells collected during apheresis is related to the volume of blood processed. In large-volume apheresis (LVL) procedure, more cells can be collected than were originally present in the peripheral blood at the start of the collection procedure. We prospectively studied the levels of CD34+ cells in the blood and apheresis product during LVL procedures for 21 patients with acute myelogenous leukemia or multiple myeloma. These patients experienced a slow decline in blood CD34+ cell concentrations during the apheresis procedure. No patient demonstrated a sustained rise in CD34+ cell counts as a result of the procedure. The number of CD34+ cells collected exceeded the number calculated to be in the peripheral blood at the start of the procedure by an average of 3.0-fold. The efficiency of collection for CD34+ cells averaged 92.6% and did not vary with speed of blood processing, diagnosis, or mobilization regimen. The calculated release of CD34+ cells from other reservoirs into the peripheral blood averaged 3.71 x 10(6)/min (range, 0.36-13.7 x 10(6)/min), and correlated (r = 0.82) with the concentration of these cells in the peripheral blood at the start of the procedure. These data show that the apheresis procedure used in this study does not affect the release of CD34+ cells in a cytokine-treated patient. LVL will result in collection of larger quantities of CD34+ cells than procedures involving processing of smaller volumes of blood, but the number of cells collected is limited by the rate of release of these cells into the peripheral circulation where they are accessible for collection.

Non-cryopreserved peripheral blood progenitor cells collected by a single very large-volume leukapheresis: a simplified and effective procedure for support of high-dose chemotherapy

High-dose chemotherapy with autologous peripheral blood progenitor cell (PBPC) support has become a widely used treatment strategy. In order to simplify the procedure, a single very large-volume leukapheresis programme combined with short-term refrigerated storage of the PBPC was developed. Seventy-two patients suffering from various relatively chemosensitive malignancies received high-dose chemotherapy, consisting of agents with short in vivo half-lives and 24 to 48 hours later, the refrigerated PBPC were reinfused. A single very large-volume apheresis was sufficient to obtain at least 2 x 10(6)/kg CD34+ cells in 58 patients (81%), and 63% had at least 2.5 x 10(6) CD34+ cells/kg. Only two patients (3%) were transplanted with less than 1 x 10(6) CD34+ cells/kg. In three patients (4%) leukapheresis was repeated because of insufficient number of PBPC. The median CD34+ cell count was 3 x 10(6)/kg. A median of 38.5 L blood (range, 21 to 59) was processed, which accounted for a median of 9 x patient's total blood volume. Very large-volume leukapharesis was well tolerated with symptomatic hypocalcemia being the most common (18%) side-effect. The median time to neutrophils >1.5 x 10(9)/L, and to self-supporting platelet count >25 x 10(9)/L, was 10 and 12 days after reinfusion of PBPC graft, respectively. There were no treatment-related deaths. Our results indicate that this simplified approach of PBPC transplantation can be associated with prompt hematologic recovery in most patients and that it can be useful in settings where facilities are limited or for certain diseases where conditioning regimens with short half-life are appropriate. J. Clin. Apheresis, 15:236-241, 2000.

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.

Kinetic study of CD34+ cells during peripheral blood stem cell collections

The impact of the separated volume on the yield of CD34+ cells during peripheral blood stem cell collections (PBSCC) remains controversial. We therefore studied the CD34+ cell concentration in the peripheral blood of patients (pts) during PBSCC as well as the total amount of CD34+ cells collected after each blood volume (BV) processed and engraftment data for each cycle of high dose chemotherapy (HD Ctx). A total of 21 PBSCC from 20 patients with different malignancies were analyzed. Stem cells were mobilized by chemotherapy and G-CSF (14 pts) or GM-CSF (6 pts). Samples from the pts peripheral blood and the collection bag were taken after each BV processed and analyzed for CD34+ cells, WBC, platelets (plt), and hemoglobin (Hb). The total volume processed was two to five times the pts calculated BV (mean value 17.4 L, range 9.0-24.0 L). Sixteen pts could be evaluated for engraftment. The mean peripheral blood CD34+ cell count was 116+/-103.5/microl at the start of PBSCC and decreased to 57+/-61.6/microl after processing of four times the pts BV. The mean number of CD34+ cells collected after each BV was 2.3+/-2.4, 5.8+/-5.2, 8.5+/-7.2, and 11.8+/-10.3x10(6) per kg body weight, respectively. The mean plt count decreased by 53+/-40.2/nl, Hb by 1.+/-0.5 g/dl and WBC by 0.+/-6.1/nl after separation of 4 BV. All but two pts reached the target value of 1.5x10(6) CD34+ cells/kg body weight and planned cycle of HD Ctx with 1 PBSCC. All pts engrafted and reached neutrophils>500/microl and plt>20,000/microl at a median of 11 and 13 days, respectively. We could demonstrate, that the yield of CD34+ cells during PBSCC increased continuously with the volume of the separated BV and that up to 5x the patients' BV could be processed safely without serious side effects. Most pts had to undergo only 1 PBSCC to collect sufficient numbers of CD34+ cells to support sequential courses of HD Ctx without delayed engraftment.

Femoral vascular access for large-volume collection of peripheral blood progenitor cells

Central venous catheters are used frequently in large-volume leukapheresis to provide high flow rates for peripheral blood progenitor cell (PBPC) collection. In a retrospective study, we evaluated the safety and efficacy of short-term use of large-bore femoral venous catheters for the collection of PBPCs in 63 patients with hematologic and solid organ malignancies. All catheters were placed in an outpatient setting on the day of apheresis and remained in site if subsequent collections became necessary. A total of 101 procedures were performed. Thirty-five patients (56%) reached target levels after 1 collection. Twenty-four patients (38%) had 2 consecutive day collections while 4 patients (6%) required more than 2 collections. In this latter group, 2 patients did not have consecutive day collections. One had 2 consecutive day collections followed by a third collection 48 hours later. In the other, leukapheresis was performed for 2 consecutive days and then resumed 3 days later with 2 subsequent collections. The longest duration the catheter remained in site was 6 days. Catheter care was provided by the apheresis staff. All patients who had more than 1 collection were given instructions on how to care for their catheters at home. Only 1 patient had oozing at the catheter site during the collection. Thrombosis, mechanical, and infectious complications were not encountered. The short-term use of femoral venous catheters appears safe and effective for the collection of PBPCs.

Evaluation of a new protocol for peripheral blood stem cell collection with the Fresenius AS 104 cell separator

In this report we analyzed sixty leukapheresis procedures on 35 patients with a new protocol for the Fresenius AS 104. Yields and efficiencies for MNC, CD 34+ cells, and CFU-GM indicate that the new protocol is able to collect large quantities of hemopoietic progenitors. Procedures were performed processing 8.69 +/- 2.8 liters of whole blood per apheresis and modifying 3 parameters: spillover-volume 7 ml, buffy-coat volume 11.5 ml, centrifuge speed 1,500 rpm; blood flow rate was 50 ml/min and the anticoagulant ratio was 1:12. No side effects were observed during apheresis procedures except for transient paresthesia episodes promptly resolved with the administration of calcium gluconate. Yields show a high capacity of the new program to collect on average MNC 17.28 +/- 10.85 x 10(9), CD 34+ 471 +/- 553.5 x 10(6) and CFU-GM 1278.7 +/- 1346.3 x 10(4) per procedure. Separator collection efficiency on average was 49.91 +/- 23.28% for MNC, 55.1 +/- 35.66% for CFU-GM, and 62.97 +/- 23.09% for CD 34+ cells. Particularly interesting are results for MNC yields and CD 34+ efficiency; these results make the new program advantageous or similar to the most progressive blood cell separators and capable to collect a sufficient number of progenitor cells for a graft with a mean of 1.80 +/- 0.98 procedures per patient.

A prospective, randomized, sequential crossover trial of large-volume versus normal-volume leukapheresis procedures: effects on serum electrolytes, platelet counts, and other coagulation measures

BACKGROUND

LVL procedures with the administration of heparin as an additional anticoagulant are increasingly performed because of the potentially higher yield of autologous peripheral blood HPCs. A prospective, randomized crossover trial was performed to evaluate the influence of leukapheresis volume-that is, large versus normal-on serum electrolytes, platelet count, and other coagulation measures in 25 patients with breast cancer and 14 patients with non-Hodgkin's lymphoma.

STUDY DESIGN AND METHODS

Patients were randomly assigned to start either with an LVL on Day 1 followed by a normal-volume leukapheresis (NVL) on Day 2 or vice versa. In LVL, heparin was administered in addition to ACD-A. Bleeding complications, transfusion support, whole-blood counts, and several coagulation measures as well as plasma heparin levels were evaluated.

RESULTS

Although the duration, the infused amount of ACD-A, the flow rate, the drop in platelet count, and the drop in potassium were significantly greater in LVL, and although LVL patients also received heparin, there was no significant difference in clinical tolerance or bleeding complications. After LVL, patients exhibited a significantly longer activated partial thromboplastin time (APTT), with a median of 70 seconds (range, 44-100 sec), and a median anti-factor Xa activity of 0.69 IU per mL (range, 0.10-1.29 IU/mL). The value of the APTT after LVL correlated with anti-factor Xa activity (r = 0.37, p<0.05), but not with platelet count or heparin infusion rate. Markers for coagulation activation did not increase during NVL or LVL.

CONCLUSION

LVL with heparin as an additional anticoagulant seems to be a safe procedure in patients with low preleukapheresis platelet counts. No activation of coagulation occurred after NVL or LVL procedures.

Volume-dependent collection of peripheral blood progenitor cells during large-volume leukapheresis for patients with solid tumours and haematological malignancies

We investigated the efficacy of peripheral blood progenitor cell (PBPC) collection during large-volume leukapheresis (LVL) in patients with solid tumours and haematological malignancies (n = 18). The time- and volume-dependent harvest of leucocytes (WBC), mononuclear cells (MNC), CD34+ cells and colony-forming cells (CFU-GM) during LVL was analysed in six sequentially filled collection bags processing four times the patient's blood volumes. The amounts of leucocytes (WBC) and the purity of mononuclear cells (MNC%) did not show any significant changes during LVL. The percentage of CD34+ cells remained constant for the first three bags but consecutively decreased from initially 1.71% CD34+ cells in the beginning of LVL to finally 1.34% CD34+ cells (P = 0.02). The mean numbers of colony-forming cells (CFU-GM) decreased from 74 microL-1 to 59 microL-1 during LVL (P = 0.16). Furthermore, the comparison of volume-dependent PBPC collection for patients with high, medium and low total yields of CD34+ cells showed similar kinetics on different levels for the three groups. We concluded that - relative to the initial total amount of PBPC harvested - comparable numbers of progenitor cells can be collected during all stages of LVL with a slight decreasing trend processing four times the patient's blood volumes.

A prospective, randomized, sequential, crossover trial of large-volume versus normal-volume leukapheresis procedures: effect on progenitor cells and engraftment

BACKGROUND

The influence of leukapheresis size on the number of harvested peripheral blood progenitor cells is still unclear. A prospective randomized crossover trial was thus performed, to evaluate the effect of large-volume leukapheresis (LVL) versus normal-volume leukapheresis (NVL) on progenitor cells and engraftment in 26 patients with breast cancer and 15 patients with non-Hodgkin's lymphoma who were eligible for peripheral blood progenitor cell transplantation.

STUDY DESIGN AND METHODS

Patients were randomly assigned to undergo either LVL on Day 1 and on Day 2 or vice versa. The number of progenitor cells was evaluated in the harvest and before and after leukapheresis in the peripheral blood.

RESULTS

The number of harvested CD34+ cells (4.8 x 10(6) vs. 3.4 x 10(6)/kg body weight, p < 0.001) and colony-forming units-granulocyte-macrophage (3.1 x 10(5) vs. 2.4 x 10(5)/kg body weight, p = 0.0026) was significantly higher for LVL procedures than for NVL procedures. The median extraction efficacy, defined as the difference between the yield in the harvest and the decrease in the total number of CD34+ cells in peripheral blood during leukapheresis, was significantly (p < 0.0001) higher for LVL than for NVL (2.6 x 10(8) and 8 x 10(7), respectively). In patients with breast cancer, the median amount of CD34+ cells in the harvest and the median extraction efficacy were higher for LVL than for NVL (p < 0.0001). This was not found for patients with non-Hodgkin's lymphoma.

CONCLUSION

LVL results in a higher yield of CD34+ cells and colony-forming units-granulocyte-macrophage than NVL, but only in patients with breast cancer and with high numbers of CD34+ cells in the peripheral blood before leukapheresis.

Large-volume leukaphereses may be more efficient than standard-volume leukaphereses for collection of peripheral blood progenitor cells

To overcome the need for multiple leukaphereses to collect enough PBPC for autologous transplantation, large-volume leukaphereses (LVL) are used to process multiple blood volumes per session. We compared the efficiency of CD34+ cell collection by LVL (n = 63; median blood volumes processed 11.1) with that of standard-volume leukaphereses (SVL) (n = 38; median blood volumes processed 1.9). To achieve this in patients with different peripheral blood concentrations of CD34+ cells, we analyzed the ratio of CD34+ cells collected per unit of blood volume processed, divided by the number of CD34+ cells in total blood volume at the beginning of apheresis. For LVL, 30% (9%-323%) of circulating CD34+ cells were collected per blood volume compared with 42% (7%-144%) for SVL (p = 0.02). However, in LVL patients, peripheral blood CD34+ cells/L decreased a median of 54% during LVL (similar data for SVL not available). The number of CD34+ cells collected per blood volume processed after 4 and 8 blood volumes and at the end of LVL were 0.32 (0.01-2.05), 0.24 (0.01-1.68), and 0.22 (0.01-2.40) x 10(6) CD34+ cells/kg, respectively (p = 0.0007), despite the 54% decrease in peripheral blood CD34+ cells/L throughout LVL. A median 66% decrease in the platelet count was also observed during LVL. Thus, LVL may be more efficient than SVL for PBPC collection, allowing, in most patients, the collection in one LVL of sufficient PBPC to support autologous transplantation.

Autologous peripheral blood stem cells: collection and processing

The rapid development in the area of collecting and processing autologous peripheral blood stem cells (PBSC) is reflected by the escalating number of patients treated with PBSC, and by the increasing amount of literature on the subject. Clinical experience suggests that among the variables with a negative influence on mobilization of PBSC, the most important may be the amount of previous stem cell toxic chemotherapy. In selecting patients suitable for autologous PBSC support, the requirement of an adequate anti-tumor therapy has to be weighed against the risk of chemotherapy related stem cell toxicity which will result in inability to collect a sufficient amount of PBSC. The general consensus is that a sufficient PBSC-autograft should contain 2-5 x 10(6) CD34+/kg body weight, but attempts to provide a recommended optimal or threshold level are hampered by the lack of standardized methods for CD34+ cell enumeration. In addition, the time to haematological recovery depends both on the dose of infused CD34+ cells and also on the amount of previous chemotherapy, which affects both the quality of the graft and the supportive microenvironment of the host. The quality of the autograft may also be contaminated by malignant cells, even if the biological significance of tumor cell detection in the PBSC graft has not yet been established. Recent development of methods for in vitro purging and selection of CD34+ cells for clinical use have provided the means to avoid or reduce reinfusion of malignant cells. Future directions of clinical research include the ability to define and enumerate the proportion of stem cells versus committed progenitor cells among the CD34+ cells in a PBSC collection, which will be important to ensure rapid engraftment as well as long term haematopoiesis.

Successful collection and transplantation of peripheral blood stem cells in cancer patients using large-volume leukaphereses

It was the aim of our study to determine the collection efficiency and yield of CD34+ cells in 88 cancer patients (pts, 44 males/44 females) who underwent 154 large-volume leukaphereses (LV-LPs). The diagnoses were as follows: 18 patients had Non-Hodgkin's lymphoma, 9 Hodgkin's disease, 24 multiple myeloma, 6 acute leukemia, 27 breast cancer, and 4 patients had solid tumors of different types. During the course of LV-LPs, 20 liters (1) of blood were processed at a median flow-rate of 85 ml/min (CS 3000 Baxter) and 130 ml/min (COBE Spectra), respectively. Peripheral blood stem cells (PBSC) were collected following granulocyte colony-stimulating factor (G-CSF)-supported cytotoxic chemotherapy. A 31% and 21% mean decrease in the platelet and white blood count was noted at the end of the LV-LPs when compared with the pre-leukapheresis values. The aphereses were well tolerated without adverse effects. The level of circulating CD34+ cells was closely related to the number of CD34+ cells contained in the respective leukapheresis product (R = 0.89, P < 0.001). Compared with 270 patients who underwent 838 regular 10 1 LPs, the yield of CD34+ cells/kg was almost two-fold greater (4.84 +/- 0.63 x 10(6) [Mean +/- SEM] vs. 2.60 +/- 0.16 x 10(6), P < 0.001). The antigenic profile of CD34+ cells was assessed in 54 separate products collected on the occasion of 27 LV-LPs following the processing of 10 1 and 20 1, respectively. The intra-individual comparison included differentiation- as well as lineage-associated markers (CD38, Thy-1, c-kit, CD33, CD45RA). No difference in the subset composition was observed between the first and second product, arguing against a preferential release of particular CD34+ cell subsets during the procedure. As shown by molecular biological or immunocytochemical examination, the likelihood of harvesting malignant cells using large-volume aphereses was not increased in comparison with regular leukaphereses. Single harvests of > or = 2.5 x 10(6) CD34+ cells/kg could be obtained in 74% of the patients, compared with 52% in case of regular LPs. As the majority of patients were autografted with more than 2.5 x 10(6) CD34+ cells/kg following high-dose therapy, hematological recovery in general was rapid and not related to the type of apheresis product used. Considering patient comfort and savings in resource utilization, large-volume leukaphereses have become the standard procedure for PBSC collection in our center.