Predictive parameters for granulocyte colony-stimulating factor-induced peripheral blood stem cell mobilization

Scoping review of factors associated with stem cell mobilization and collection in allogeneic stem cell donors

BACKGROUND

There is a large inter-individual variation in the efficacy of CD34+ cell mobilization and collection in healthy allogenic hematopoietic stem cell donors. Donor characteristics, blood cell counts, and factors related to mobilization and collection have previously been associated with blood CD34+ cell count or CD34+ cell yield after G-CSF mobilization and collection. Since the literature reporting associations is heterogeneous, we clarify the determinants of CD34+ count and yield in a scoping review.

MATERIALS AND METHODS

Studies published between 2000 and 2023 were evaluated if they reported allogeneic donors undergoing G-CSF mobilization and peripheral blood stem cell collection (PBSC). Eligible studies assessed blood CD34+ cell count or CD34+ cell yield in the first PBSC collection after mobilization with 4 or 5 days of G-CSF treatment. Associations were recorded between these outcomes and donor factors (age, gender, weight, ethnicity), mobilization factors (G-CSF scheduling or dose), collection factors (venous access, processed blood volume) or laboratory factors (blood cell counts at baseline or after mobilization).

RESULTS

The 52 studies each evaluated between 15 and 20,884 donors. 43 studies were retrospective, 33 assessed blood CD34+ cell counts and 39 assessed CD34+ cell yield from PBSC. Blood CD34+ cell counts consistently predicted CD34+ cell yield. Younger donors usually had higher blood CD34+ cell counts and CD34+ cell yield. Most studies that investigated the effect of donor ancestry found that non-European ancestry donors had higher blood CD34+ cell counts after mobilization and CD34+ cell yields from collection.

CONCLUSIONS

There remains poor consensus about the best predictors of blood CD34+ cell counts and yield that requires further prospective study, particularly of the role of donor ancestry. The current focus on donor gender as a major predictor requires re-evaluation.

Lactate dehydrogenase as a hematopoietic stem cell mobilization biomarker in autologous transplantation

INTRODUCTION

Pre-apheresis peripheral blood CD34+ cell count (PBCD34+) is the most important predictor of good cell mobilization before hematopoietic stem cell transplantation, albeit flow cytometry is not always immediately available. Identification of surrogate markers can be useful. The CD34+ cells proliferate after mobilization, resulting in elevated lactate dehydrogenase (LDH) activity and correlating with the PBCD34+ count.

OBJECTIVE

To determine the LDH cut-off value at which adequate CD34+ cell mobilization is achieved and its diagnostic yield.

MATERIALS AND METHODS

A total of 103 patients who received an autologous stem cell transplantation (ASCT) between January 2015 and January 2020 were included. Demographic and laboratory characteristics were obtained, including complete blood count, pre-apheresis PBCD34+ and LDH levels. Receiver operating characteristic (ROC) curves were performed to identify the optimal serum LDH activity cut-off points for ≥ 2 and ≥ 4 × 106 cells/kg post-mobilization CD34+ count and their diagnostic yield.

RESULTS

A post-mobilization serum LDH cut-off value of 462 U/L yielded a sensitivity (Se) = 86.8% (positive predictive value [PPV] = 72.7%), a pre- and post-mobilization serum LDH difference cut-off value of 387 U/L, an Se = 45.7% (PPV = 97%) and an LDH ratio of 2.46, with an Se = 47.1% (PPV = 97%) for an optimal mobilization count (CD34+ ≥ 4 × 106).

CONCLUSION

The LDH measurement represents a fast and affordable way to predict PBCD34+ mobilization in cases where flow cytometry is not immediately available. According to the LDH diagnostic yield, it could be used as a surrogate marker in transplant centers, supporting the CD34+ count, which remains the gold standard.

In vivo HSC transduction in rhesus macaques with an HDAd5/3+ vector targeting desmoglein 2 and transiently over-expressing cxcr4

We developed a new in vivo hematopoietic stem cell (HSC) gene therapy approach that involves only intravenous injections and does not require myeloablation/conditioning and HSC transplantation. In this approach, HSCs are mobilized from the bone marrow into the peripheral blood stream and transduced with intravenously injected helper-dependent adenovirus (HDAd) vectors. A fraction of transduced HSCs returns to the bone marrow and persists there long-term. Here, we report desmoglein 2 (DSG2) as a new receptor that can be employed for in in vivo HSC transduction. We developed HDAd5/3+ vectors that use DSG2 as a high-affinity attachment receptor and studied in vivo HSC transduction and safety after intravenous injection of an HDAd5/3+GFP vector in G-CSF/AMD3100(Plerixafor)-mobilized rhesus macaques. Unlike previously used CD46-targeting HDAd5/35++ vectors, HDAd5/3+ virions were not sequestered by rhesus erythrocytes and therefore mediated ~10-fold higher GFP marking rates in primitive HSCs (CD34+/CD45RA-/CD90+ cells) in the bone marrow at day 7 after vector injection. To further increase the return of in vivo transduced, mobilized HSCs to the bone marrow, we transiently expressed CXC motif chemokine receptor 4 (cxcr4) in mobilized HSCs from the HDAd5/3+ vector. In vivo transduction with a HDAd5/3+GFP/cxcr4 vector at a low dose of 0.4x1012vp/kg resulted in up to 7% of GFP-positive CD34+/CD45RA-/CD90+ cells in the bone marrow. This transduction rate is a solid basis for in vivo base or prime editing in combination with natural or drug-induced expansion of edited HSCs. Furthermore, our study provides new insights into HSC biology and trafficking after mobilization in non-human primates.

Plerixafor-based mobilization in pediatric healthy donors with unfavorable donor/recipient body weight ratio resulted in a better CD34+ collection yield: A retrospective analysis

INTRODUCTION

In order to propose risk-adapted mobilization algorithms, several authors have tried to look for predictive factors of the CD34⁺ yield in healthy pediatric donors. Donor recipient body weight ratio (D/R ratio) was identified as one of the main variables related with the success to achieve the target cell dose for transplantation. According to this variable we modified the mobilization schedule.

MATERIAL AND METHODS

We report the results of 46 mobilizations and apheresis procedures performed in our center with unfavorable D/R ratio. Mobilization was attempted by the standard regime of G-CSF (10 mcg/kg/24 hours) in 28 cases (60.9%), with high dose G-CSF (10 mcg/kg/12 hours) in 9 cases (19.6%), and with plerixafor and G-CSF single dose regime in 9 cases (19.6%).

RESULTS

CD34⁺ cell quantification before apheresis is closely related to CD34⁺ yield, being the only factor related to collected CD34⁺ cells (beta .71; P < .0001). The mobilization efficiency was higher in plerixafor group compared to the other two schedules (P < .0001). By using plerixafor for mobilization, we achieved the target CD34⁺ cell dose of ≥2 × 10⁶ /kg per recipient body weight in all cases with unfavorable D/R ratio. It was observed that 17.4% of cases that not reached the established target cell dose were located in the standard or high-dose mobilization regimes. This difference is even greater for optimal collections (≥5 × 10⁶ /kg), since of the 54.3% cases that did not reach this goal none was mobilized by plerixafor.

CONCLUSION

Tailoring the mobilization regime we can reach the target cell dose, even in those cases with the worst D/R ratio.

Analysis of a large single institution cohort of related donors fails to detect a relation between SDF1/CXCR4 or VCAM/VLA4 genetic polymorphisms and the level of hematopoietic progenitor cell mobilization in response to G-CSF

We studied a cohort of 367 healthy related donors who volunteered to donate their hematopoietic stem cells for allogeneic transplantation. All donors were homogeneously cared for at a single institution, and received rhG-CSF as a mobilization treatment prior to undergoing apheresis. Peripheral blood CD34+ cell counts were used as the main surrogate marker for rhG-CSF induced mobilization. We searched whether inter-individual variations in known genetic polymorphisms located in genes whose products are functionally important for mobilization, could affect the extent of CD34+ mobilization, either individually or in combination. We found little or no influence of individual SNPs or haplotypes for the SDF1, CXCR4, VCAM and VLA4 genes, whether using CD34+ cell counts as a continuous or a categorical variable. Simple clinical characteristics describing donors such as body mass index, age and possibly sex are more potent predictors of stem cell mobilization. The size of our cohort remains relatively small for genetic analyses, however compares favorably with cohorts analyzed in previously published reports suggesting associations of genetic traits to response to rhG-CSF; notwithstanding this limitation, our data do not support the use of genetic analyses when the choice exists of several potential donors for a given patient.

The healthy donor profile of immunoregulatory soluble mediators is altered by stem cell mobilization and apheresis

BACKGROUND

Peripheral blood stem cells from healthy donors mobilized by granulocyte colony-stimulating factor (G-CSF) and thereafter harvested by leukapheresis are commonly used for allogeneic stem cell transplantation.

METHODS

Plasma levels of 38 soluble mediators (cytokines, soluble adhesion molecules, proteases, protease inhibitors) were analyzed in samples derived from healthy stem cell donors before G-CSF treatment and after 4 days, both immediately before and after leukapheresis.

RESULTS

Donors could be classified into two main subsets based on their plasma mediator profile before G-CSF treatment. Seventeen of 36 detectable mediators were significantly altered by G-CSF; generally an increase in mediator levels was seen, including pro-inflammatory cytokines, soluble adhesion molecules and proteases. Several leukocyte- and platelet-released mediators were increased during apheresis. Both plasma and graft mediator profiles were thus altered and showed correlations to graft concentrations of leukocytes and platelets; these concentrations were influenced by the apheresis device used. Finally, the mediator profile of the allotransplant recipients was altered by graft infusion, and based on their day +1 post-transplantation plasma profile our recipients could be divided into two major subsets that differed in overall survival.

DISCUSSION

G-CSF alters the short-term plasma mediator profile of healthy stem cell donors. These effects together with the leukocyte and platelet levels in the graft determine the mediator profile of the stem cell grafts. Graft infusion also alters the systemic mediator profile of the recipients, but further studies are required to clarify whether such graft-induced alterations have a prognostic impact.

The kinetics of hematopoietic niche cytokines and their influence on mobilization efficacy and timing in patients with hematological malignancies

The bone marrow niche functions are modulated by complicated cytokines network. The aim of our study was to evaluate the levels of VCAM-1, VEGF, MMP-9 and SDF during mobilization of CD34+ cells in patients with hematological malignancies. Thirty four patients were enrolled to the study (19F, 15 M) at median age of 57 years. The group consisted of patients with multiple myeloma (26) and lymphoma (8). The mobilization procedures comprised chemotherapy and then G-CSF. Blood samples were collected before chemotherapy (N = 34) and on the day of the first apheresis (N = 26). Cytokines were evaluated with ELISA assay. We observed significant increase in VCAM-1 levels during mobilization. On contrary, VEGF and SDF levels decreased during mobilization procedure. The levels of MMP-9 were stable during mobilization. We divided patients according to baseline cytokines levels below and above median into "low" and "high" expressors. The group of VEGF "low" expressors had longer median time of G-CSF treatment before first apheresis than 'high' expressors. Baseline VEGF levels correlated adversely with duration of G-CSF treatment before first apheresis. Patients were also divided according to median cytokines levels at apheresis into "low" and "high" expressors. "High" VCAM-1 expressors had higher CD34+in peripheral blood as well as higher CD34+numbers collected during first apheresis than "low" expressors. In conclusion, the levels of niche cytokines change significantly during mobilization in patients with hematopoietic malignancies. Baseline VEGF can influence timing of mobilization. Higher VCAM-1 corresponds with higher mobilization efficacy.

Angiopoietins in haematopoietic stem cell mobilisation in patients with haematological malignancies

BACKGROUND

The bone marrow niche contains different types of cells including osteoblasts and endothelial progenitors, all of which interact and take part in the process of mobilisation. The aim of our study was to evaluate the levels of cytokines (osteopontin and angiopoietins 1 and 2) active in the bone marrow niche during the mobilisation of haematopoietic stem cells for autologous transplantation.

MATERIALS AND METHODS

Forty-eight patients (24 females, 24 males), median age 56.5 years, entered the study. The group consisted of patients with multiple myeloma (n=34), lymphoma (n=13) and acute myeloid leukaemia (n=1). Blood samples were collected before chemotherapy and on the day of the first apheresis. Cytokines were evaluated by enzyme-linked immunosorbent assays. Additionally, circulating endothelial cells were assessed by flow cytometry.

RESULTS

The median concentration of angiopoietin 1 at the time of apheresis was lower than that at baseline (2.7 vs 7.8 ng/mL, p<0.001). In contrast, the median level of angiopoietin 2 increased during the mobilisation procedure (3.6 vs 2.8 ng/mL, p=0.001). The patients were divided according to the number of days of granulocyte colony-stimulating factor treatment before the first apheresis into "early" (<median=11 days) and "late" (>median) mobilisers. The group of "early mobilisers" had higher baseline angiopoietin 1 levels (median=11.6 ng/mL) than those of the "late mobilisers" (median=6.0 ng/mL, p=0.05). An adverse correlation was observed between duration of granulocyte colony-stimulating factor treatment and baseline angiopoietin 1 level. Baseline angiopoietin 1 levels correlated with numbers of circulating endothelial cells. Low angiopoietin 2 level increased the chance of poor mobilisation.

CONCLUSIONS

The angiogenic processes can influence the timing of mobilisation. Angiopoietins 1 and 2 need further evaluation in the context of mobilisation.

Circulating endothelial cell kinetics and their potential predictive value during mobilization procedure

OBJECTIVE

Circulating endothelial cells (CECs) in patients with hematological malignancies are assessed as a noninvasive marker of angiogenesis. The aim of this study was to evaluate the numbers of CECs and their subsets during mobilization of hematopoietic stem cells.

PATIENTS AND METHODS

Thirty-eight patients were enrolled to the study (19 females and 19 males) at median age of 56.5 years. The group consisted of patients with multiple myeloma (26), lymphoma (10), and acute myeloid leukemia (2). Blood samples were collected before chemotherapy (0), 1 day after chemotherapy (Cht+1), on the day G-CSF commenced (G0), after 1 day of G-CSF (G+1), and on the day of the first apheresis. CECs were evaluated by four-color flow cytometry. Circulating progenitor cells were defined as CD45-/CD34+/CD31+/CD133+. Apoptotic CECs (ApoCECs) were defined as CD146+/AnnexinV+.

RESULTS

Median (Me) CECs number was 10.5/µl and it decreased after chemotherapy (Me = 8.3/µl, P < 0.001 when compared with baseline). Based on the number of aphereses needed to obtain 2 × 10(6)/kg CD34+ cells, patients were divided into "highly efficient" (one apheresis) and "poorly efficient" mobilizers (two or more aphereses). Median ApoCEC at Day G+1 was lower in highly efficient than in poorly efficient mobilizers (Me = 3.1/µl vs. Me = 5.1/µl, P = 0.02). ApoCEC at Day G+1 correlated with the number of aphereses (r = 0.48, P = 0.03). In multivariate analysis, ApoCEC at Day G+1 was an independent factor for successful mobilization during one apheresis.

CONCLUSIONS

CECs and their subsets change significantly during mobilization of HSCs. ApoCECs measured at the time of G-CSF commencement can predict the efficacy of HSC collection.

Basal levels of CD34 positive cells in peripheral blood differ between individuals and are stable for 18 months

BACKGROUND

Detection of basal levels of CD34 progenitor cells is a rare event analysis enumerating cells down to 1 cell/μl. A reproducible analytic approach was used in three independent clinical trials in which multiple sequential assays were obtained from the same individual.

METHODS

A 4 color panel combining, HLA-DR, CD34, CD45, and CD11b was used in a dual platform analysis to quantify CD34 progenitor cells in peripheral blood, with quality control focused at the lowest measurements (i.e., basal levels), where assay error is greatest.

RESULTS

Repeat testing of individuals every 4 h over the course of 6 days provided a unique opportunity to assess the precision of the analytic technique and identified basal differences between individuals. In a second study, the basal levels were stable for 10 weeks while in a third study the individual differences were maintained for 18 months. This approach was then used to monitor the kinetics of mobilization of CD34 cells following G-CSF stimulation every 4 h.

CONCLUSIONS

The differences between individuals in basal levels of CD34 were shown to be a biologic constant, stable for 18 months and not a result of the variability of the assay, shown by low coefficients of variation for each individual. These results can be used to augment a quality control program by monitoring individuals over time to establish intra and inter-laboratory assay precision. In addition, the response of six individuals to G-CSF demonstrated differences in absolute numbers of mobilized CD34 progenitor cells but showed identical kinetics, peaking at 80-110 h.

Impact of constitutional polymorphisms in VCAM1 and CD44 on CD34+ cell collection yield after administration of granulocyte colony-stimulating factor to healthy donors

Background The number of CD34(+) cells mobilized from bone marrow to peripheral blood after administration of granulocyte colony-stimulating factor varies greatly among healthy donors. This fact might be explained, at least in part, by constitutional differences in genes involved in the interactions tethering CD34(+) cells to the bone marrow.

DESIGN AND METHODS

We analyzed genetic characteristics associated with CD34(+) cell mobilization in 112 healthy individuals receiving granulocyte colony-stimulating factor (filgrastim; 10 μg/kg; 5 days).

RESULTS

Genetic variants in VCAM1 and in CD44 were associated with the number of CD34(+) cells in peripheral blood after granulocyte colony-stimulating factor administration (P = 0.02 and P = 0.04, respectively), with the quantity of CD34(+) cells ×10⁶/kg of donor (4.6 versus 6.3; P < 0.001 and 7 versus 5.6; P = 0.025, respectively), and with total CD34(+) cells ×10⁶ (355 versus 495; P = 0.002 and 522 versus 422; P = 0.012, respectively) in the first apheresis. Of note, granulocyte colony-stimulating factor administration was associated with complete disappearance of VCAM1 mRNA expression in peripheral blood. Moreover, genetic variants in granulocyte colony-stimulating factor receptor (CSF3R) and in CXCL12 were associated with a lower and higher number of granulocyte colony-stimulating factor-mobilized CD34(+) cells/μL in peripheral blood (81 versus 106; P = 0.002 and 165 versus 98; P=0.02, respectively) and a genetic variant in CXCR4 was associated with a lower quantity of CD34(+) cells ×10⁶/kg of donor and total CD34(+) cells ×10⁶ (5.3 versus 6.7; P = 0.02 and 399 versus 533; P = 0.01, respectively). Conclusions In conclusion, genetic variability in molecules involved in migration and homing of CD34(+) cells influences the degree of mobilization of these cells.