Donor body mass index is an important factor that affects peripheral blood progenitor cell yield in healthy donors after mobilization with granulocyte-colony-stimulating factor

Scoping Review of Factors Associated with Stem Cell Mobilization and Collection in Allogeneic Stem Cell Donors

There is wide interindividual variation in the efficacy of CD34+ cell mobilization and collection in healthy allogenic hematopoietic stem cell donors. Donor characteristics, blood cell counts, and various factors related to mobilization and collection have been associated with blood CD34+ cell count and CD34+ cell yield after granulocyte colony-stimulating factor (G-CSF) mobilization and collection. Given the heterogenous nature of the literature reporting these associations, in this scoping review we clarify the determinants of CD34+ count and yield. Studies published between 2000 and 2023 reporting allogeneic donors undergoing G-CSF mobilization and peripheral blood stem cell (PBSC) collection were evaluated. Eligible studies were those that 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, sex, weight, ethnicity), mobilization factors (G-CSF scheduling or dose), collection factors (venous access, processed blood volume [PBV]) or laboratory factors (blood cell counts at baseline or after mobilization). The 52 studies evaluated between 15 and 20,884 donors. Forty-three studies were retrospective, 33 assessed blood CD34+ cell counts, and 39 assessed CD34+ cell yield from PBSCs. 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 donors of non-European ancestry had higher blood CD34+ cell counts after mobilization and higher CD34+ cell yields from collection. The poor consensus about the best predictors of blood CD34+ cell count and yield necessitates further prospective studies, particularly of the role of donor ancestry. The current focus on donor sex as a major predictor requires re-evaluation.

Improving cellular therapy operations through pre-harvest measurement of peripheral CD34-positive cell counts in allogeneic stem cell harvest

INTRODUCTION

Previously, our institution measured peripheral blood CD34 cell counts both pre- and post-peripheral blood stem cell harvest (PBSCH), with both samples analyzed simultaneously post-PBSCH. Since 2021, we have measured pre-CD34 cell counts during PBSCH, adjusting the processed blood volume based on these results. We retrospectively evaluated how this change impacted cellular therapy.

METHODS

Related healthy donors were included and divided into 1-day and 2-day harvest cohorts. Donors with CD34 cell counts measured post- and during PBSCH were categorized into the previous and current sub-cohorts, respectively.

RESULTS

Regarding the 1-day cohort (n = 212), the current sub-cohort had a significantly shorter average harvest duration (151 [standard deviation, SD = 45.1] vs. 180 [SD = 27.8] minutes, respectively) and higher average infusion rates (87.6% [SD = 21.1] vs. 78.1% [SD = 25.7], respectively) than the previous sub-cohort.

CONCLUSION

Adjusting the processed blood volume based on pre-PBSCH CD34 cell counts measured during the harvest may reduce donor burden and enhance workflow efficiency.

Peripheral Blood Allogeneic Stem Cell Mobilization: Can We Predict a Suboptimal Mobilization?

Allogeneic peripheral blood stem cells mobilization is now the basis of most stem cell transplants. In a very limited number of cases, mobilization is suboptimal leading to further collection procedures, to suboptimal cell doses infusion with delayed engraftment time, increased risks of transplant procedure and of related costs. To date we have no recognized and shared criteria for early estimating the probability of poor mobilization in healthy donors. We then analyzed allogeneic peripheral blood stem cell donations performed at the Fondazione Policlinico Universitario A.Gemelli IRCCS Hospital from January 2013 to December 2021 in order to identify premobilization factors associated with successful mobilization. The following data were collected: age, gender, weight, complete blood cell count at baseline, G-CSF dose, number of collection procedures, CD34+ cell count in peripheral blood on the first day of collection, CD34+ cell dose per kg body weight of recipient. Mobilization efficacy was defined according to the number of CD34+ cells in peripheral blood on day +5 of G-CSF administration. We classified donors as sub-optimal mobilizers or good mobilizers according to the achievement of the 50 CD34+ cell/μL threshold. We observed 30 suboptimal mobilizations in 158 allogeneic peripheral blood stem cell donations. Age and baseline white blood cell count were factors significantly associated with negative or positive impact on mobilization, respectively. We did not find significant differences in mobilization based on gender or G-CSF dose. Using cut-off values of 43 years and 5.5×10⁹/L WBC count, we built a suboptimal mobilization score: donors who reach 2, 1 or 0 points have a 46%, 16% or 4% probability of suboptimal mobilization, respectively. Our model explains 26% of the variability of mobilization confirming that most of the mobilization magnitude depends on genetically determined factors; however, suboptimal mobilization score is a simple tool providing an early assessment of mobilization efficacy before G-CSF administration begins in order to support allogeneic stem cells selection, mobilization and collection. Through a systematic review, we looked for confirmation of our findings. According to the published articles, all the variables we included in our model are confirmed to be strongly related to the success of mobilization. We believe that score system approach could be applied in clinical practice to assess the risk of mobilization failure at baseline allowing for a priori intervention.

Plerixafor and granulocyte colony stimulating factor for poor mobilizers in patients undergoing autologous peripheral hematopoietic stem cell transplantation: Single institution study

Background

Autologous hematopoietic stem cell transplantation (ASCT) has become the mainstay treatment for many hematological malignancies and solid tumors. An adequate number of stem cells must be collected for better ASCT outcomes, which is challenging in 5%-30% of patients. To improve mobilization, plerixafor is used along with granulocyte colony-stimulating factor (G-CSF).

Patients and methods

We conducted a retrospective single center study involving patients who received plerixafor pre-ASCTs between January 2013 and December 2020 at a tertiary care center in Lebanon. We identified a total of 84 consecutive adult patients. All patients identified were poor mobilizers and have eventually received plerixafor either as pre-emptive use before first apheresis in those with peripheral CD34 + of less than 20 cells/ul, or after failure of first apheresis in those with peripheral stem cells (PSC) >2.0 × 106 cells/Kg.

Results

The median age at ASCT was 52.7 years (22-74) with 61% male predominance. Multiple myeloma was the most prevalent disease 64% followed by Lymphoma 32%. The majority of patients were in complete remission 64% at the time of ASCT. Most patients received proteasome inhibitor-based induction therapy 67% and Melphalan-based conditioning therapy 68%. The median follow-up from ASCT was 9 months (1-59). It was noted that greater body mass index (BMI) is a significant factor for better PSC collection whether premobilization (P = 0.003), or post plerixafor mobilization (P = 0.024). Moreover, Multiple Myeloma patients showed better mobilization using Plerixafor (P = 0.049). Using Plerixafor along with G-CSF in poor mobilizers post G-CSF alone showed a statistically significant increase in the collected PSC mean from 0.67 × 106 cells/Kg to 4.90 × 106 cells/Kg (P < 0.001) with a failure rate only for 12 patients (15%). The infusion of PSC > 2.5 × 106 cells/Kg has shown 3 days decrease in time to platelet engraftment (P = 0.021) and a 36% decrease in progression/relapse rate (P = 0.025).

Conclusion

Plerixafor is effective in increasing the PSC yield in poor mobilizers. Low BMI and hematologic malignancies other than Multiple Myeloma are risk factors for poor mobilization. More studies should be performed to establish more risk factors, helping us to identify poor mobilizers more accurately and initiate plerixafor mobilization early on.

Long-acting granulocyte colony-stimulating factor pegfilgrastim (lipegfilgrastim) for stem cell mobilization in multiple myeloma patients undergoing autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is a standard of care in newly-diagnosed multiple myeloma (MM) patients. Several studies before the introduction of novel therapies in MM, demonstrated a pegylated G-CSF to be successful in mobilizing peripheral blood stem cells (PBSCs). Lipegfilgrastim is a novel long-acting G-CSF that is produced by the conjugation of a single 20-kDa polyethelene glycol to the natural O-glycosylation site of G-CSF. Twenty-four MM patients were included for PBSCs mobilization with a single SC injection of 6 mg lipegfilgrastim. PBSC collection was started when the CD34⁺ count was > 10 × 10⁶ cells/L. The target progenitor cells were 6 × 10⁶ cells/kg. The median day of apheresis was + 3 (range 2-5) following lipegfilgrastim. Median peripheral blood CD34⁺ count pre-mobilization was of 22.65 (range 3.36-105) × 10⁶ cells/L. The median number of leukaphaeresis procedures was 2 (range 1-4). The median mobilized CD34⁺ cells/kg were 8.26 (range 0.77-12.42). One patient failed to mobilize and two patients mobilized < 6 × 10⁶ cells/kg. Toxicity was mild and transient. Twenty-three patients underwent ASCT following high dose melphalan. All patients engrafted. As lipegfilgrastim is administered only once, it is conceivable that it improves both compliance and quality-of-life (NCT02488382).

Weighty choices: selecting optimal G-CSF doses for stem cell mobilization to optimize yield

There are limited data on the effect of donor body mass index (BMI) on peripheral blood stem cell (PBSC) mobilization response to granulocyte colony-stimulating factor (G-CSF), especially in unrelated donors. Obesity has been associated with persistent leukocytosis, elevated circulating progenitor cells, and enhanced stem cell mobilization. Therefore, we hypothesized that adequate collection of CD34+ cells may be achieved with lower doses (per kilogram of body weight) of G-CSF in donors with higher BMI compared with donors with lower BMI. Using the Center for International Blood and Marrow Transplant Research database, we evaluated the impact of donor BMI on G-CSF-mobilized PBSC yield in healthy unrelated donors. We examined 20 884 PBSC donations collected at National Marrow Donor Program centers between 2006 and 2016. We found significantly higher collection yields in obese and severely obese donors compared with normal and overweight donors. An increase in average daily G-CSF dose was associated with an increase in stem cell yield in donors with normal or overweight BMI. In contrast, an increase in average daily G-CSF dose beyond 780 μg per day in obese and 900 μg per day in severely obese donors did not increase cell yield. Pain and toxicities were assessed at baseline, during G-CSF administration, and postcollection. Obesity was associated with higher levels of self-reported donation-related pain and toxicities in the pericollection and early postdonation recovery periods. This study suggests a maximum effective G-CSF dose for PBSC mobilization in obese and severely obese donors, beyond which higher doses of G-CSF add no increased yield.

Shorter Interdonation Interval Contributes to Lower Cell Counts in Subsequent Stem Cell Donations

Approximately 7% of unrelated hematopoietic stem cell donors are asked to donate stem cells a subsequent time to the same or a different recipient. Recent studies have shown that donation-related symptoms for second donations are similar to those for the first donation. Little is known about differences in stem cell mobilization and yields for subsequent peripheral blood stem cell (PBSC) and bone marrow (BM) collections. We hypothesized that CD34⁺ cell yields and total nucleated cell (TNC) concentrations for subsequent PBSC or BM donations are lower than those at the first donation. We also evaluated the factors influencing stem cell yields in healthy unrelated second-time donors. Data were gathered from the Center for International Blood and Marrow Transplant Research database on 513 PBSC and 43 BM donors who donated a second time between 2006 and 2017 through the National Marrow Donor Program. Among the second-time PBSC donors, we found significantly lower preapheresis peripheral blood CD34⁺ cell counts (68.6 × 10⁶/L versus 73.9 × 10⁶/L; P = .03), and collection yields (556 × 10⁶ versus 608 × 10⁶; P = .02) at the second donation compared to the first. This decrease at the subsequent donation was associated with a shorter interdonation interval, lower body mass index (BMI), and a lower total G-CSF dose. In most instances, suboptimal mobilizers at their first donation donated suboptimal numbers of stem cells at their subsequent donations. Among repeat BM donors, the TNC concentration was lower at the second donation. The small size of this group precluded additional analysis. Overall, when considering repeat donations, increasing the interdonation intervals and evaluating for BMI changes should be considered to optimize stem cell yields. Some of these parameters may be improved by increasing G-CSF dose in PBSC donors within permissible limits.

Getting blood out of a stone: Identification and management of patients with poor hematopoietic cell mobilization

Hematopoietic cell transplantation (HCT) has become a primary treatment for many cancers. Nowadays, the primary source of hematopoietic cells is by leukapheresis collection of these cells from peripheral blood, after a forced egress of hematopoietic cells from marrow into blood circulation, a process known as "mobilization". In this process, mobilizing agents disrupt binding interactions between hematopoietic cells and marrow microenvironment to facilitate collection. As the first essential step of HCT, poor mobilization, i.e. failure to obtain a desired or required number of hematopoietic cell, is one of the major factors affecting engraftment or even precluding transplantation. This review summarizes the available mobilization regimens using granulocyte-colony stimulating factor (G-CSF) and plerixafor, as well as the current understanding of the factors that are associated with poor mobilization. Strategies to mobilize patients or healthy donors who failed previous mobilization are discussed. Multiple novel agents are under investigation and some of them have shown the potential to enhance the mobilization response to G-CSF and/or plerixafor. Further investigation of the risk factors including genetic factors will offer an opportunity to better understand the molecular mechanism of mobilization and help develop new therapeutic strategies for successful mobilizations.

Smoking is an important factor that affects peripheral blood progenitor cells yield in healthy male donors

BACKGROUND

Smoking could reduce the CD34+ cells in peripheral blood of healthy individual. This study aimed to investigate the correlation between smoking load and the effect of peripheral blood hematopoietic progenitor cells (PBPCs) mobilization by granulocyte colony-stimulating factor (G-CSF) alone in healthy donors.

METHODS

Retrospective analysis was performed on 145 healthy adult PBPCs donors who underwent PBPCs mobilization and collection. Smoking factors were evaluated and correlated with mobilization responses, as indicated by the collected CD34+ cells concentration.

RESULTS

The collected CD34+ cells concentration was closely related to pre-CD34 (P < .001) and CD34+ cells collected per volume blood processed (P < .001) which suggested that collected CD34+ cells concentration was a reliable indicator of PBPCs mobilization efficiency. The heavy smoking donors revealed significantly lower collected CD34+ cells concentration, compared to that of the nonsmoking (P < .001) and light smoking donors (P < .05). The levels of collected CD34+ cells in light smoking were also obviously lower than that in nonsmoking donors (P < .05).There were no obvious differences in the collected CD34+ cells concentration, overall processed blood volume and total collected CD34+ cells between nonsmoking and smoking cessation groups (P = .490; P = .464; P = .819).

CONCLUSION

Cigarette smoking is an important factor that affects the yield of PBPCs in male donors, especially when the smoking load is more than five pack-years. Mobilization of PBMCs could be restored by smoking cessation in chronic smokers.

Who is the best haploidentical donor for acquired severe aplastic anemia? Experience from a multicenter study

BACKGROUND

Haploidentical transplantation has been proposed as an effective treatment for severe aplastic anemia (SAA). The majority of patients have more than one HLA-haploidentical donor. Herein, we compared the outcomes between different donor-recipient relationships for optimal haploidentical donor selection in acquired SAA.

METHODS

We conducted a multicenter study based on a registered database of 392 patients with SAA treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT) between 2006 and 2018. In total, 223 patients received grafts from father donors, 47 from mother donors, 91 from siblings, 29 from children, and 2 from collateral donors.

RESULTS

Of the 381 patients who survived more than 28 days, 379 (99.5%) recipients were engrafted. The 2-year overall survival (OS) was 86.6 ± 2.5%, 87.1 ± 4.9%, 84.3 ± 3.9%, and 92.2 ± 5.1% for recipients of father, mother, sibling, and child grafts, respectively, (P = 0.706). The 2-year failure-free survival (FFS) was 82.8 ± 2.7%, 86.7 ± 5.1%, 80.8 ± 4.2%, and 92.5 ± 5.1% for recipients of father, mother, sibling, and child grafts, respectively, (P = 0.508). There was no difference in the incidence of either acute or chronic graft-versus-host disease (GVHD) among the different donor sources in multivariate analyses. There were also no differences in the OS or FFS among the different donor sources in the Cox regression analysis. However, OS was significantly better in the patients with a shorter history of aplastic anemia (< 12 months), better performance status (ECOG scores 0-1), or moderate graft mononuclear cell (MNC) counts (6-10 × 10⁸/kg), and in female recipients with male donors. The FFS was also higher in patients with a shorter history of aplastic anemia (< 12 months) and better performance status (ECOG scores 0-1).

CONCLUSIONS

Fathers, mothers, siblings, and children are all suitable haploidentical donors for patients with SAA.

Evaluation of peripheral blood mononuclear cell collection by leukapheresis

BACKGROUND

Adoptive immunotherapy using engineered lymphocytes has shown promising results in treating cancers even in patients who have failed other treatments. As the first essential step, the number of peripheral mononuclear cell (MNC) collection procedures is rapidly increasing. In this retrospective study, we reviewed the collection results to determine factors that affect MNC collection.

STUDY DESIGN AND METHODS

We reviewed 184 collections that were performed on 169 adult allogenic donors and patients with acute lymphoid leukemia, chronic lymphoid leukemia, lymphoma, multiple myeloma, or solid-organ tumors. All the leukapheresis procedures were performed after a complete cell count with differential was obtained. Total blood volume (TBV) was defined as processed blood volume divided by patient blood volume.

RESULTS

There was a significant association between the precollection MNC count (pre-MNC) and the MNC yields normalized by TBV (r = 0.926; p < 0.001) and a regression formula was created to predict MNC yields. Multiple regression analyses showed that pre-MNC, TBV, and precollection hemoglobin were strongly associated with MNC yield (R ² = 0.866; F (3180) = 388.472; p < 0.001), and pre-MNC had the greatest influence on MNC yield (β = 0.960; p < 0.001) followed by TBV (β = 0.302; p < 0.001), and Hgb (β = 0.136; p < 0.001).

CONCLUSION

Our results suggest that the optimal time for MNC collection can be determined based on pre-MNC and that processing volume should be determined based on collection goal and pre-MNC to optimize and personalize the harvesting procedure.

Factors affecting hematopoietic stem cell mobilization and apheresis in allogeneic donors: The role of iron status

Infused CD34 cell count has a significant impact on transplant outcome. In this retrospective study, we aimed to analyze the impact of donor iron parameters on peripheral blood stem cell (PBSC) collection. A total of 303 related donors were included in the study. The mobilization regimen, recombinant G-CSF, was given for four consecutive days. A CD34⁺ cell count below 2×10⁶/kg was defined as mobilization failure which was demonstrated in 23 donors (7.6%). Mobilization failure was more frequent in female donors than male donors (13.7% vs 3.4%). Body mass index, mean corpuscular volume, hemoglobin and ferritin levels were found to be lower in donors with mobilization failure. Body mass index was significantly correlated with PBSC count on the 4th day of G-CSF. Body mass index, male gender, mean corpuscular volume and ferritin levels had significant impact on PBSC count. Although PBSC count was found to be similar between female and male donors, female gender was shown to have an adverse impact on PBSC collection, which may be attributed to lower body weight and concurrent iron deficiency.

Collection and immunoselection of CD34+ cells: the impact of age, sex, and diabetes in patients with chronic heart failure

BACKGROUND

Mobilized peripheral blood is the most common source of CD34+ cells intended for transplantations. The collection and enrichment of CD34+ cells could be affected by various factors and there are some controversies regarding the effects of patient-related factors. The aim of this study was to assess the impact of age, sex, and diabetes on the CD34+ cell grafts in patients with chronic heart failure.

STUDY DESIGN AND METHODS

Cell grafts from 100 adult patients scheduled for autologous CD34+ cell transplantation were investigated. The CD34+ cells were collected using leukapheresis after granulocyte-colony-stimulating factor mobilization and further enriched using the immunomagnetic CD34+ selection. The number of CD34+ cells and their viability were determined by flow cytometry.

RESULTS

Older patients had significantly lower CD34+ cell counts than younger patients. The differences between men and women were not found. There was a trend toward an inverse relationship between diabetes and the CD34+ cell count, however, without any significance. No differences in the CD34+ cell viability (97.6% before and 97.9% after selection) were found. The mean CD34+ cell recovery was 59.7% and was not statistically different between age groups, sex, and diabetic patients.

CONCLUSION

Before the CD34+ cells are collected the patient's age should be considered. The study did not demonstrate a significant impact of sex and diabetes on the CD34+ cell count. While age and sex did not affect the immunoselection process, diabetes slightly reduced cell recovery. Cell viabilities before and after the cell enrichment were comparable between the tested samples.

Hematopoietic stem and progenitor cell harvesting: technical advances and clinical utility

Hematopoietic stem and progenitor cell (HSPC) transplantations require prior harvesting of allogeneic or autologous HSPCs. HSPCs are usually present in bone marrow (BM) during the entire life, in cord blood (CB) at birth, or in peripheral blood (PB) under particular circumstances. HSPCs were first harvested in BM and later in CB and PB, as studies showed interesting features of such grafts. All harvesting methods were in use throughout the years, except BM harvesting for HSPC autologous transplantation, which was replaced by PB harvesting. BM, CB, and PB harvesting methods have been developed, and materials and devices technically improved to increase the number of HSPCs harvested. In parallel, knowing the features of the donors or patients associated with successful numbers of HSPCs allows the adaptation of appropriate harvesting methods. Moreover, it is important to ensure the safety of donors or patients while harvesting. This review describes the methods used for harvesting based on recent studies or developments around these methods, and more particularly, the means developed to increase the numbers of HSPCs harvested in each method. It also explains briefly the influence of technical improvements in HSPC harvesting on potential changes in HSPC graft composition.

Predictors of the yield of mobilized peripheral blood CD34+ cells in HLA-matched sibling donor

We examined the donor factors that may affect the yield of peripheral blood stem cell (PBSC) mobilized from healthy donors. Pre-apheresis PB-CD34(+) cell count was the only factor that correlated with PBSC yield. Leukocyte count (LC) and monocyte count (MC) correlated with PB-CD34(+) cell. Male gender and PB-CD34(+) cell count of at least 87.1/μL and 69.8/μL on day-4 and -5 of G-CSF were associated with the ability to harvest at least 5×10(6)/kg CD34(+) cells after one apheresis. We concluded that gender and PB-CD34(+) cell count are important predictors of PBSC yield. LC and MC may serve as surrogate markers for estimating the PB-CD34(+) cell count.