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

Optimizing autologous stem cell collections for patients with multiple myeloma receiving G-CSF and Plerixafor: A single center project

BACKGROUND

Increasing indications for cellular therapy collections have stressed our healthcare system, with autologous collections having a longer than desired wait time until apheresis collection. This quality improvement initiative was undertaken to accommodate more patients within existing resources.

STUDY DESIGN AND METHODS

Patients with multiple myeloma who underwent autologous peripheral blood stem cell collection from October 2022 to April 2023 were included. Demographic, mobilization, laboratory, and apheresis data were retrospectively collected from the medical record.

RESULTS

This cohort included 120 patients (49.2% male), with a median age of 60 years. All received G-CSF and 95% received pre-emptive Plerixafor approximately 18 hours pre-collection. Most (79%) had collection goals of at least 8 × 106/kg CD34 cells, with 63% over 70 years old having this high collection goal (despite 20 years of institutional data showing <1% over 70 years old have a second transplant). With collection efficiencies of 55.9%, 44% of patients achieved their collection goal in a single day apheresis collection. A platelet count <150 × 103/μL on the day of collection was a predictor for poor mobilization; among 27 patients with a low baseline platelet count, 17 did not achieve the collection goal and 2 failed to collect a transplantable dose.

CONCLUSIONS

With minor collection goal adjustments, 15% of all collection appointments could have been avoided over this 6-month period. Other strategies to accommodate more patients include mobilization modifications (Plerixafor timing or substituting a longer acting drug), utilizing platelet counts to predict mobilization, and modifying apheresis collection volumes or schedule templates.

Evaluating the efficiency and safety of large-volume leukapheresis using the Spectra Optia continuous mononuclear cell collection protocol for peripheral blood stem cell collection from healthy donors: A retrospective study

BACKGROUND

Large-volume leukapheresis (LVL) refers to processing of more than three volumes of blood in a single session for peripheral blood stem cell collection. Recently, continuous mononuclear cell collection (cMNC) protocol has been developed using the Spectra Optia system, which is a widely used apheresis device. LVL using the novel protocol has been investigated in patients. However, the efficiency and safety of LVL in healthy donors using this protocol has not been characterized. Therefore, this study aimed to evaluate the efficiency and tolerability of CD34+ collection of LVL with the cMNC protocol in healthy donors.

STUDY DESIGN AND METHODS

We retrospectively collected data on LVL (>3 total blood volume) and normal-volume leukapheresis (NVL) performed in healthy donors between October 2019 and December 2021. All procedures were performed using the cMNC protocol.

RESULTS

Although pre-apheresis CD34+ cell count was lesser in LVL (23.5 vs. 58.0/μL, p < .001), CD34+ collection efficiency was comparable between LVL and NVL (61.2% vs. 61.4%, p = .966). Platelet loss was significantly higher in LVL compared to NVL (38.0% vs. 29.4%, p < .001), with no correlation between attrition of platelet and processing blood volume. Moreover, the incidence of citrate toxicity during procedures was comparable between the two groups (31.6% vs. 21.4%, p = .322). All LVL procedures could be completed without any adverse events.

CONCLUSION

Allogeneic LVL procedure using Spectra Optia cMNC protocol was well tolerated by the donors and resulted in efficient collection of CD34+ cells, which was comparable to that of NVL.

Validation of simple prediction algorithms to consistently achieve CD3+ and postselection CD34+ targets with leukapheresis

BACKGROUND

Cellular therapies using engineered T cells, haploidentical transplants, and autologous gene therapy are increasing. Specified CD3+ or high CD34+ doses are typically required for subsequent manufacturing, manipulation, or CD34+ selection. Simple, practical, and reliable lymphocyte and hematopoietic progenitor cell (HPC) collection algorithms accounting for subsequent CD34+ selection have not been published.

STUDY DESIGN AND METHODS

In this analysis of 15 haploidentical donors undergoing tandem lymphocyte and HPC collections, we validated one-step, practical prediction algorithms (Appendix S1, available as supporting information in the online version of this paper) that use conservative facility-specific collection efficiencies, CD34+ selection efficiency, and donor-specific peripheral counts to reliably achieve the target CD3+ and CD34+ product doses. These algorithms expand on our previously published work regarding predictive HPC collection algorithms.

RESULTS

Ninety-three percent of lymphocyte and 93% of CD34+ collections achieved the final target CD3+ and CD34+ product dose when our algorithm-calculated process volumes were used. Linear regression analysis of our algorithms for CD3+, preselection CD34+, and postselection CD34+ showed statistically significant models with R² of 0.80 (root mean square error [RMSE], 31.3), 0.72 (RMSE, 385.7), and 0.56 (RMSE, 326.0), respectively, all with p values less than 0.001.

CONCLUSION

Because achievement of CD3+ or CD34+ dose targets may be critical for safety and efficacy of cell therapies, these simple, practical, and reliable prediction algorithms for lymphocyte and HPC collections should be very useful for collection facilities.

Comparison of two apheresis systems for autologous stem cell collections in pediatric oncology patients

BACKGROUND

Peripheral stem cell collections can be challenging in the pediatric population and respective experience is limited. Since February 2015 our institution is utilizing the new Spectra Optia (Optia) apheresis device, which has replaced the former COBE Spectra (COBE) device. As a quality initiative we collected and compared collection efficiency (CE2) and other collection variables between the two devices.

STUDY DESIGN AND METHODS

In this retrospective study we collected and compared clinical, laboratory, and technical collection data from stem cell collection procedures done with the Optia and COBE devices. The collected data included patient demographics, precollection peripheral CD34+ cell counts, total CD34+ cells collected, complete blood count, electrolytes before and after collection, side effects attributed to the collection, total blood volumes processed (TBVs), collection times, and calculated CE2 and collection ratios.

RESULTS

Forty-one collection procedures performed on 29 pediatric patients with the Optia device were compared to 41 collections performed on 27 patients with the COBE device. The TBVs through the Optia device were significantly smaller than the COBE (3.9 ± 0.2 × TBV vs. 5.5 ± 0.1 × TBV, respectively; p < 0.001), requiring significantly less anticoagulant and providing similar amounts of stem cells while collection times were significantly shorter (mean, 238 ± 9 min vs. 264 ± 9 min, respectively; p < 0.05). Collections on the Optia caused significantly smaller reductions of plasma calcium and magnesium. No significant side effects attributed to the procedure were noted.

CONCLUSION

Stem cell apheresis with the Optia device in children is safe and feasible with smaller blood volumes with shorter collection times.

Comparison between intermittent and continuous spectra optia leukapheresis systems for autologous peripheral blood stem cell collection

Terumo BCT recently introduced a new system for mononuclear cell (MNC) collection that uses a Spectra Optia apheresis machine equipped with a redesigned disposable kit and software program (version 11.2). It allows for the continuous collection of MNCs, unlike the original Spectra Optia system (version 7.2), which included a chamber for two-step cell separation. The aim of this study was to compare the two apheresis systems in regard to specific performance parameters. A retrospective data analysis of 150 patients who had undergone peripheral blood stem cell collection between March of 2014 and May of 2015 at our institution was performed. For the matched comparison, patients were divided into two groups by diagnosis and by previous forms of therapy received: a homogeneous group of patients with multiple myeloma (MM) that had received first line therapy ("MM" group, n = 88) and a heterogeneous group that included all of the other patients ("other" group, n = 62). No significant differences in CD34+ collection yields between both collection regimens were found (p_MM  = 0.19, p_other  = 0.74) in either group. Moreover, similar performance ratios (collected/predicted CD34+ cell number in %) were observed (p_MM  = 0.89, p_other  = 0.1). No relevant variations in platelet or hemoglobin loss were found between the two systems. We conclude that the new continuous Spectra Optia MNC system is equally efficient in collecting CD34+ cells and can be used without sacrificing collection efficiency levels when treating a broad variety of autologous patients. J. Clin. Apheresis 32:27-34, 2017. © 2016 Wiley Periodicals, Inc.

Unstimulated leukapheresis in patients and donors: comparison of two apheresis systems

BACKGROUND

Unstimulated mononuclear cell (MNC) apheresis plays a role in the generation of donor lymphocytes (DLIs; healthy donors) and in extracorporeal photopheresis (ECP; patients). The new apheresis system Spectra Optia MNC has been shown in small studies to be capable of performing the desired cell collections, but larger data sets from real-life clinical apheresis procedures are lacking.

STUDY DESIGN AND METHODS

Presented are comparative data from DLI collections randomly performed with either the new technology or a clinical standard technology, COBE Spectra MNC, as well as data from patients with chronic graft-versus-host disease undergoing MNC collections alternating between the two apheresis systems to generate products for ECP. Target cell yield and collection efficiency, product volume, nontarget cell contamination, platelet (PLT) attrition, and some process variables such as process volume and time were analyzed.

RESULTS

For most relevant apheresis outcomes, differences between the devices were at best marginal. Spectra Optia MNC collections in patients, but not in donors, took 10% longer to achieve the target process volume. Not unexpectedly, given previous observations for granulocyte-colony-stimulating factor-stimulated leukapheresis, the novel device collected smaller products with less red blood cell contamination. PLT attrition with Spectra Optia MNC was markedly lower in donors. ECP apheresis outcome variability was, to a significant degree, donor dependent, irrespective of the device used.

CONCLUSION

Based on more than 200 unstimulated apheresis procedures, we conclude that both apheresis systems are safe, robust, and equally suitable for unstimulated MNC collections. Both can be successfully run with manufacturer-recommended settings and algorithms.

The effective use of plerixafor as a real-time rescue strategy for patients poorly mobilizing autologous CD34(+) cells

Plerixafor enhances CD34(+) cell mobilization, however, its optimal use is unknown. We hypothesized that plerixafor could "rescue" patients in the midst of mobilization when factors indicated a poor CD34(+) yield. Of 295 consecutive autologous peripheral blood mobilization attempts at our center, 39 (13%) used plerixafor as rescue strategy due to a CD34(+) cell concentration <10/μl (median 5.95/μl, n = 30), low CD34(+) cell yield from prior apheresis day (median 1.06 × 10(6) CD34(+) cells/kg, n = 7), or other (n = 2). Patients received a median of one plerixafor dose (range: 1-4). Thirty-four (87%) collected =2 × 10 (6) CD34(+) cells/kg and 26 (67%) collected =4 × 10 (6) CD34(+) cells/kg. Median collections for lymphoma (n = 24) and myeloma (n = 15) patients were 4.1 × 10(6) and 8.3 × 10(6) CD34/kg, respectively. A single dose of plerixafor was associated with an increase in the mean peripheral blood CD34(+) concentration of 17.2 cells/μl (P < 0.001) and mean increased CD34(+) cell yield following a single apheresis of 5.11 × 10(6) /kg (P < 0.03). A real-time rescue use of plerixafor is feasible and may allow targeted use of this agent. J. Clin. Apheresis, 2012. © 2012 Wiley Periodicals, Inc.

Harvesting, processing and inventory management of peripheral blood stem cells

By 2003, 97% autologous transplants and 65% of allogeneic transplants in Europe used mobilised peripheral blood stem cells (PBSC). Soon after their introduction in the early 1990's, PBSC were associated with faster haemopoietic recovery, fewer transfusions and antibiotic usage, and a shorter hospital stay. Furthermore, ease and convenience of PBSC collection made them more appealing than BM harvests. Improved survival has hitherto been demonstrated in patients with high risk AML and CML. However, the advantages of PBSC come at a price of a higher incidence of extensive chronic GVHD. In order to be present in the blood, stem cells undergo the process of “mobilisation” from their bone marrow habitat. Mobilisation, and its reciprocal process – homing – are regulated by a complex network of molecules on the surface of stem cells and stromal cells, and enzymes and cytokines released from granulocytes and osteoclasts. Knowledge of these mechanisms is beginning to be exploited for clinical purposes. In current practice, stem cell are mobilised by use of chemotherapy in conjunction with haemopoietic growth factors (HGF), or with HGF alone. Granulocyte colony stimulating factor has emerged as the single most important mobilising agent, due to its efficacy and a relative paucity of serious side effects. Over a decade of use in healthy donors has resulted in vast experience of optimal dosing and administration, and safety matters. PBSC harvesting can be performed on a variety of cell separators. Apheresis procedures are nowadays routine, but it is important to be well versed in the possible complications in order to avoid harm to the patient or donor. To ensure efficient collection, harvesting must begin when sufficient stem cells have been mobilised. A rapid, reliable, standardized blood test is essential to decide when to begin harvesting; currently, blood CD34+ cell counting by flow cytometry fulfils these criteria. Blood CD34+ cell counts strongly correlate with the apheresis yields. These are, in turn, predictive of the speed of haemopoietic recovery after transplantation, which has helped establish the adequate cell dose for transplantation. Following collection, PBSC may be transfused unmanipulated, processed to select specific cell subtypes, or stored for future use. Cryopreservation techniques allow long term storage of stem cells without significant loss of viability. Increasingly demanding calls for safety led to introduction of vapour phase storage, separate storage of infected material, and mandatory quality control measures at all stages of the cryopreservation process and subsequent thawing and transfusion. At the same time, safety of the personnel working in stem cell processing and storage laboratories is safeguarded by a set of regulations devised to minimize the risk of infection, injury or hypoxia. Requirements for quality and safety have been shaped into a number of documents and directives in Europe and USA, emphasising the importance of product traceability, reporting of adverse reactions, quality management systems (standard operating procedures, guidelines, training records, reporting mechanisms and records), requirements for cell reception, quarantine, process control, validation and storage. Establishments that collect, process and store stem cells must be accredited or licensed by appropriate national or international authorities on a regular basis. These regulatory measures have recently become law across the European Union.

Automatic interface-controlled apheresis collection of stem/progenitor cells: results from an autologous donor validation trial of a novel stem cell apheresis device

BACKGROUND

Cryopreserved hematopoietic progenitor cells collected by apheresis from granulocyte-colony-stimulating factor with or without chemotherapy-mobilized patients have become the preferred type of autograft to support treatment of diseases amenable to high-dose chemotherapy. A novel apheresis system, the Spectra Optia v.5.0 (CaridianBCT), was constructed to meet certain shortcomings of manual apheresis systems such as the COBE Spectra MNC (CaridianBCT), including the need for continuous optical or manual monitoring and readjustment of buffy coat position and sensitivity to inconsistent blood flow. By use of optical sensors, which provide real-time automatic interface (buffy coat) and collection line control, the Spectra Optia promises to automatically guide apheresis procedures, potentially freeing up operator time and reducing variability in collection efficiency (CE2).

STUDY DESIGN AND METHODS

In a two-center clinical trial, 35 autologous stem cell donors were subjected to apheresis with the Spectra Optia to validate feasibility and effectiveness of apheresis procedures. Results were compared to data from 80 autologous apheresis procedures with the COBE Spectra MNC.

RESULTS

Usability and function of the automatic interface management were excellent. CD34+ cell quality, assessed by viability staining, colony-forming unit-culture frequency, and engraftment kinetics, was equally good with both systems. CE2 of the Spectra Optia, calculated as CD34+ contents in the product divided by the number of CD34+ cells presented to the collection port, exceeded that of the COBE Spectra MNC. Spectra Optia product volumes were significantly smaller. Very high white blood cell and platelet counts modestly reduced CE2 with the Spectra Optia.

CONCLUSION

The Spectra Optia is a novel automatic apheresis system supporting autologous stem cell collection with at least equal efficiency and superior user-friendliness compared to the COBE Spectra MNC.

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

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

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.

CD34+ cell adhesion molecule profiles differ between patients mobilized with granulocyte-colony-stimulating factor alone and chemotherapy followed by granulocyte-colony-stimulating factor

BACKGROUND

High-dose therapy with autologous peripheral blood progenitor cell support is widely utilized but requires successful CD34+ cell mobilization and collection. Chemotherapy plus growth factors appear to mobilize more CD34+ cells than growth factors alone. Because alterations in expression of adhesion molecules are important in the trafficking of hematopoietic progenitors, the possibility was explored that the mechanism of this superior mobilization may be greater down regulation of adhesion molecules.

STUDY DESIGN AND METHODS

The expression of eight adhesion molecules (CD11a, b, and c; 15s; 49d and e; 54; and 62L) on the collected CD34+ cells from 15 patients undergoing mobilization with chemotherapy plus granulocyte-colony-stimulating factor (G-CSF) was compared with those of 14 concomitant patients receiving G-CSF alone.

RESULTS

Patients receiving chemotherapy plus G-CSF mobilized more CD34+ cells and did not differ in prior chemotherapy or radiation. There were no significant differences in the percentage of CD34+ cells expressing any of the adhesion molecules examined between the two groups. The chemotherapy plus G-CSF-mobilized cells consistently showed higher expression intensity, and this showed significance or a strong trend for CD11a and c, CD15s, and CD54. Despite these higher expression levels, there were no differences in engraftment kinetics.

CONCLUSIONS

CD34+ cells mobilized by chemotherapy plus growth factors appear to have higher intensities of expression of several adhesion molecules. The significance of this observation will require further study.

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.

Good and poor mobilizing patients differ in mobilized CD34+ cell adhesion molecule profiles

BACKGROUND

Alterations in expression of adhesion molecules are important in the trafficking of hematopoietic progenitors and probably in the mobilization process. Relatively little and conflicting data are currently available on the differences in expression between good and poor mobilizing patients.

STUDY DESIGN AND METHODS

In this study, the expression of eight adhesion molecules on the collected CD34+ cells from 36 patients undergoing mobilization was determined.

RESULTS

Good mobilizing patients, defined as those who collected their target in one apheresis procedure, had significantly fewer cells that expressed CD11a (LFA-1) and CD54 (ICAM-1) and borderline fewer that expressed CD11c, CD49d (VLA-4), and CD49d (VLA-5). No differences were detected in CD11b (Mac-1), CD15s (sLe(x)), or CD62L (L-selectin). Linear regression analysis identified number of prior chemotherapy courses and expression of CD11a (LFA-1) as independent predictive factors for mobilization efficiency. Good and poor mobilizing patients had approximately the same number of total CD34+ cells collected and little difference in times to engraftment.

CONCLUSIONS

CD11a (LFA-1) expression inversely correlates with mobilization efficiency. Elucidation of the mechanism(s) underlying these observations will require further study.

Factors affecting the efficacy of peripheral blood progenitor cells collections by large-volume leukaphereses with standardized processing volumes

BACKGROUND

Peripheral blood progenitor cell (PBPC) collections should be safe and efficient. Therefore, the influence and risk factors in large-volume leukaphereses (LVL) with standardized blood volumes was investigated.

STUDY DESIGN AND METHODS

In a total of 724 autologous LVL performed at our center, either 4x or 6x the patient's blood volume (PBV) was processed. The group with processing 4x the PBV showed a median of 31 circulating CD34+ cells per microL, and the group with processing 6x the PBV had a median of 13 CD34+ cells per microL before LVL. Individual clinical factors, laboratory factors, and apheresis run variables influencing the yields of PBPCs were retrospectively analyzed. Furthermore, the changes of laboratory variables and adverse effects during LVL were investigated.

RESULTS

Multivariate analysis identified "age,""circulating CD34+ cells," and "percentage of mononuclear cells" as only factors influencing the yields of PBPCs. Altogether, processing 6x versus 4x the PBV did not result in significantly higher yields of CD34+ cells for the total group, but requested PBPC yields were achieved more often after processing 6x the PBV in patients below 20 CD34+ cells per microL blood. Processing 6x versus 4x the PBV showed a significant difference for the decrease of platelets, but not for any other laboratory variable. Adverse effects were recorded in 4.97 percent of LVL without accumulation in one group.

CONCLUSION

In particular, patients with low amounts of circulating CD34+ cells profited from enlarged LVL demonstrating higher PBPC yields but comparable rates of adverse effects.

Improving the efficiency of PBPC collection by pre-apheresis peripheral blood and mid-apheresis product measurements of CD34 cells

BACKGROUND

The adequacy of HPC collection for BMT is typically assessed by the number of CD34 cells. However, during a series of leukapheresis procedures (LP) the CD34 value on the final HPC product may not be available for testing until late evening, sometimes resulting in additional, retrospectively unnecessary, LP in order to ensure an adequate HPC collection (>5x10(6) CD34/kg). We hypothesized that an estimate of the CD34 content of HPC products prior to 16:00 h on the day of LP would permit improved HPC collection planning. We therefore assessed the effectiveness of predicting the total amount of CD34 cells that would be collected in a given LP by either (a) the concentration of CD34 cells/microL in peripheral blood prior to LP (pre-CD34) or (b) the predicted total amount of CD34 cells to be collected based on sampling the LP product at the mid-point of each LP. We also compared the number of LP per patient and total HPC collected for the study group with data from the previous calendar year.

METHODS

Allogeneic and autologous BMT donors who completed a 20-L HPC collection between September 2002 and February 2003 were eligible. CD34 cells were measured on blood drawn prior to LP and from the HPC product at the mid-point (10 L) of LP. The CD34 content of the final LP was predicted by doubling the value of total CD34 cells at the mid-run (MRp-CD34). The MRp-CD34/kg and the cumulative CD34/kg collected were made available before 16:00 h and used to determine the need for additional LP. The true CD34 content of each HPC collection was also measured from the final product the next day (CD34-FP).

RESULTS

A 20-L LP was completed and data were available from 31 patients and nine allogeneic donors who underwent a total of 85 LP for diagnoses, including 11 myeloma, 10 lymphoma, seven HD, three acute leukemia and five others. The mean (range) and correlation (R2) vs. the CD34-FP were, for pre-CD34, 54 CD34/microL (0.3-232), R2=0.66 (P<0.01), and for MRp-CD34, 3.2x10(6) CD34/kg (0.04-22.48), R2=0.90 (P<0.01). The mean number of CD34/kg collected per LP in the patients/donors was 3.4x10(6) CD34/kg (0.05-18.94). The median number of CD34 cells employed for transplant in the study group vs. controls (5.7 vs. 5.6x10(6)/kg) and the time to engraftment of neutrophils (12 vs. 11 days) and platelets (12 vs. 12 days) was similar to historical controls. However, the study group had a significantly lower median number of LP (three vs. two; P<0.02) to obtain the required collection of 5x10(6) CD34 cells/kg.

DISCUSSION

Both the pre-CD34 and the MRp-CD34 were significantly correlated with CD34-FP. However, the CD34-FP was more reliably predicted by MRp-CD34. Early availability of mid-run CD34 values was associated with a significant reduction in the number of LP required to collect 5x10(6) CD34 cells/kg, without reduction in the number of CD34 cells for transplant or prolongation of days to neutrophil or platelet engraftment.

Effect of prior chemotherapy on hematopoietic stem cell mobilization

A number of studies have suggested that prior chemotherapy correlates negatively with the efficiency of hematopoietic stem cell mobilization. However, little data exist with regard to the relative effects of the specific chemotherapeutic drug classes. We retrospectively reviewed the records of 201 consecutive patients with nonmyeloid malignancies undergoing CD34+ cell mobilization with chemotherapy+granulocyte colony-stimulating factor (G-CSF). The number of prior chemotherapy courses correlated negatively with the peripheral CD34+ cell concentration (pCD34) on the first day of collection (P<0.001). No significant correlation was found for age, gender, tumor primary, mobilization chemotherapy regimen, disease status, marrow involvement, prior radiation therapy, or dose and timing of G-CSF administration. When the number of courses of individual classes of chemotherapeutic agents was correlated with pCD34, only exposures to platinum compounds (P=0.001) and alkylating agents (P=0.01) were found to be independent negative predictive factors for pCD34. Within classes, DNA crosslinking agents and etoposide appeared possibly more damaging than DNA methylating agents and doxorubicin, respectively. None of the drug classes showed evidence of recovery. We conclude that exposure to chemotherapy, especially platinum compounds and alkylating agents, should be minimized prior to mobilization.