Hematopoietic Stem Cell Collection Research Articles

Effect and Influencing Factors of Peripheral Blood Hematopoietic Stem Cells Collection from Unrelated Donors

To analyze the effect of peripheral blood hematopoietic stem cells (PBSC) collection from unrelated donors and its influencing factors. A retrospective analysis was conducted on the mobilization and collection of PBSC from 113 unrelated donors at Yueyang Central Hospital from January 2021 to December 2023. 113 donors were successfully mobilized. The average count of PBSC mononuclear cells (MNC) and CD34+ cells were (12.40±7.41)×108/kg and (10.64±8.07)×106/kg, respectively. Univariate analysis showed that the PBSC CD34+ cells ratio of male donors was significantly higher than that in female donors (P =0.015). The peripheral blood (PB) white blood cell (WBC) count before collection was positively correlated with the PBSC nucleated cells count (r =0.388), and the donor's body weight, the PB CD34+ cell ratio before collection were positively correlated with the PBSC CD34+ cell ratio (r =0.259, r =0.780). The daily dose of rhG-CSF was negatively correlated with the PBSC CD34+ cell ratio (r =-0.285). Both rhG-CSF agents achieved successful mobilization. Multivariate analysis showed that PB WBC count before collection was a factor affecting the count of PBSC nucleated cells (P <0.001), while the PB CD34+cell ratio before collection was a factor affecting the PBSC CD34+ cell ratio (P <0.001). The mobilization and collection of PBSC from unrelated donors are good, and the PB WBC count and CD34+ cell ratio before collection are reliable indicators for predicting the collection effect.

The effect of plerixafor on autologous stem cell mobilization, cell viability, and apheresis challenges

Abstract Objective The aim of this study was to determine the efficacy of plerixafor for hematopoietic stem cell (HSC) mobilization prior to autologous stem cell transplantation (aSCT) for patients with multiple myeloma (MM) and various lymphomas, using an oncologist-guided HSC collection goal and markers of cell viability. Methods A retrospective chart review of all aSCT patients at Yale New Haven Hospital between 2017 and 2021 who met diagnostic criteria for MM, non-Hodgkin, or Hodgkin lymphoma (n = 382) was undertaken. Logistic regression evaluated plerixafor’s effect on meeting the individual’s HSC goal. The use of t-tests determined plerixafor’s relationship to HSC yield and analysis of variance testing assessed its effect on cell viability. Results Mobilization with granulocyte colony–stimulating factor (G-CSF) and plerixafor (odds ratio [OR] = 0.08; P &amp;lt; .05) relative to G-CSF alone was negatively associated with meeting the individual’s HSC goal. Diffuse large B-cell lymphoma in patients mobilized with plerixafor yielded fewer HSCs than those without plerixafor (t = –2.78; P = .03). Mobilization regimen (P = .13) had no association with HSC viability. Mobilization failure with plerixafor was rare but occurred in patients with multiple risk factors, including exposure to several rounds of HSC-affecting chemotherapy. Conclusion Plerixafor is effective across multiple diagnoses using an oncologist-driven HSC collection endpoint. Its association with mobilization failure is likely attributable to its use in patients predicted to be poor mobilizers.

Preemptive Approach to Plerixafor Use Is Optimal in Patients With Relapsed/Refractory Germ Cell Tumors Undergoing Peripheral Blood Hematopoietic Stem Cell Collection: Effect on Collection Days, Yields, and Cost.

Evidence describing the use of plerixafor in the off-label population of relapsed/refractory germ cell tumors (GCT) is limited. Weaim to describe the effect of rescue versus preemptive plerixafor use on apheresis collection days, collection yields, and cost. We retrospectively collected data on 77 consecutive patients (at least 15 years of age) with GCT who underwent peripheral blood stem cell (PBSC) collection for autologous stem cell transplant between January 1, 2020 and May 1, 2022. Depending on insurance approval, plerixafor was given either as "rescue" (after a first apheresis collection of < 5 × 106 CD34+ cells/kg) or as "preemptive" on Day 4 of granulocyte-colony stimulating factor (G-CSF) prior to the first apheresis collection, if the Day 4 peripheral blood CD34+ count was < 40 cells/μL. A total of 66% of patients who received preemptive plerixafor completed collection in 1 day, similar to good mobilizers who only needed G-CSF (71%, p = 0.366). In contrast, all poor mobilizers in the rescue group required at least 2 days of collection and had lower CD34+ cell yields than the preemptive group (7.15 vs. 9.81 × 106/kg, p = 0.0055). A cost analysis revealed that preemptive plerixafor may save approximately $7000 per patient compared with a rescue approach. Preemptive plerixafor in GCT patients undergoing PBSC collection allows relatively poor mobilizers to collect in fewer days and with lower overall cost. Fewer apheresis procedures result in less risk to the patient, increased patient satisfaction, and the ability to schedule more patients within the constraints of staffing.

Effectiveness of oral calcium to prevent citrate-related toxicity during peripheral blood hematopoietic stem cell collection – An experience from a tertiary care center

Abstract: BACKGROUND: Apheresis procedures use citrate as an anticoagulant to ensure the fluidity of extracorporeal blood. Citrate-related toxicities are common adverse effects in peripheral blood stem cell (PBSC) collections as they are lengthy procedures resulting in prolonged citrate exposure. Intravenous (IV) calcium administration during therapeutic apheresis procedures is commonly used to reduce the citrate-related toxicity in adults and pediatric population. Very few literature on the use of oral calcium for the prevention of citrate toxicity during PBSC collection are present. OBJECTIVE: The objective of this study was to evaluate the effect of prophylactic oral calcium in reducing citrate-related toxicities during PBSC collections. MATERIALS AND METHODS: A prospective cross-sectional study was carried out at a tertiary care hospital of Southern India. All participants received calcium carbonate – 1 g before and at each 100 ml of collection. Preprocedure, interim, and postprocedure serum calcium were measured. All procedures were done using Spectra Optia. The ACD (acid-citrate-dextrose) rate were between 1:8 to 1:14 and were adjusted for inlet draw rate. The total blood volume processed between 2.5 to 3 based on body weight. Reduction in calcium levels and adverse reactions due to hypocalcemia were observed. Data were analyzed using SPSS 23 software. RESULTS: The majority of the procedures were undisturbed and tolerable to oral calcium. A total of 97.3% of the study subjects did not experience any symptoms of hypocalcemia. Only 2.7% (One autologous and one allogenic donor) had symptoms attributable to hypocalcemia though they had preprocedure calcium &gt;9 mg/dl. Pre- and postprocedure calcium were compared using a paired t-test which was statistically significant. CONCLUSION: Prophylactic oral calcium in PBSC collection is an effective and easy way to the prevention of citrate-related adverse effects without affecting technical performance and product efficacy.

Impact of Anti-CD38 Monoclonal Antibody Therapy on CD34+ Hematopoietic Stem Cell Mobilization, Collection, and Engraftment in Multiple Myeloma Patients-A Systematic Review.

This systematic review examines the available clinical data on CD34+ cell mobilization, collection, and engraftment in multiple myeloma patients treated with the anti-CD38 monoclonal antibodies daratumumab and isatuximab in clinical trials and in real life. Twenty-six clinical reports were published between 2019 and February 2024. Most studies documented lower circulating CD34+ cells after mobilization compared to controls, leading to higher plerixafor requirements. Although collection yields were significantly lower in approximately half of the studies, the collection target was achieved in similar proportions of daratumumab- and isatuximab-treated and nontreated patients, and access to autologous stem cell transplant (ASCT) was comparable. This could be explained by the retained efficacy of plerixafor in anti-CD38 monoclonal antibody-treated patients, while no chemotherapy-based or sparing mobilization protocol proved superior. Half of the studies reported slower hematopoietic reconstitution after ASCT in daratumumab- and isatuximab-treated patients, without an excess of infectious complications. While no direct effect on stem cells was observed in vitro, emerging evidence suggests possible dysregulation of CD34+ cell adhesion after daratumumab treatment. Overall, anti-CD38 monoclonal antibodies appear to interfere with CD34+ cell mobilization, without consistently leading to significant clinical consequences. Further research is needed to elucidate the underlying mechanisms and define optimal mobilization strategies in this patient population.

Isolation of Human Hematopoietic Stem Cells from an Apheresis Sample.

The hematopoietic system constantly produces new blood cells through hematopoiesis, and maintaining this balance is vital for human health. This balance is maintained by self-renewing hematopoietic stem cells (HSCs) and various progenitor cells. Under typical circumstances, HSCs are not abundantly found in peripheral blood; hence, their mobilization from the bone marrow is vital. Hematopoietic growth factors achieve this effectively, enabling mobilization and thus allowing blood sample and thus HSC collection via apheresis. Securing a sufficient supply of HSCs is vital for successful hematopoietic reconstitution and the rapid integration of committed cells. Thus, isolation and expansion of HSCs are crucial for convenient extraction, production of transplantable quantities, genetic modifications for enhanced therapeutic efficacy, and as a source of increased/expanded/synthesized blood cells in vitro. In conclusion, the isolation and expansion of HSCs play pivotal roles in both regenerative medicine and hematology. This protocol describes the isolation of human HSCs by providing an overview of the primary method for isolating human hematopoietic stem cells from apheresis blood samples and sheds light on human HSC studies and developments in research and medicine.

Method comparison between hematopoietic progenitor cell and CD34+ cell counts in hematopoietic stem cell collection.

The reference method for hematopoietic stem cell enumeration is flow cytometric CD34+ cell analysis. We evaluated using the hematopoietic progenitor cell (HPC) count on the Sysmex hematology analyzer to safely replace some flow cytometric measurements performed in peripheral blood samples to guide apheresis timing. We compared HPC and CD34+ cell counts in 133 preharvest peripheral blood samples and 124 apheresis products. Pre-apheresis HPC counts ≥24 × 106/L in healthy donors and ≥36 × 106/L in lymphoma patients predicted adequate mobilization with 100% specificity and positive predictive value, saving 79% and 63% of flow cytometry analyses, respectively. Due to a positive bias (mean bias 50.26; 95% CI 36.24-64.29), a higher threshold was needed in multiple myeloma patients (HPC 132 × 106/L), saving only 24% of flow cytometry analyses. When the HPC count is above the corresponding threshold, apheresis could be safely initiated without waiting for the flow cytometry result, thereby reducing time-to-decision. Lower HPC values, however, require confirmation by flow cytometry.

Predictive model of the efficiency of hematopoietic stem cell collection in patients with multiple myeloma and lymphoma based on multiple peripheral blood markers.

Autologous hematopoietic stem cell transplantation (ASCT) has gained extensive application in the treatment of lymphoma and multiple myeloma (MM). Plenty of studies demonstrate that peripheral blood indicators could be considered potential predictive biomarkers for hematopoietic stem cells (HSCs) collection efficiency, including white blood cell count (WBC), monocyte count (Mono), platelet count (PLT), hematocrit, and hemoglobin levels. Currently, clinically practical predictive models based on these peripheral detection indicators to quickly, conveniently, and accurately predict collection efficiency are lacking. In total, 139 patients with MM and lymphoma undergoing mobilization and collection of ASCT were retrospectively studied. The study endpoint was successful collection of autologous HSCs. We analyzed the effects of clinical characteristics and peripheral blood markers on collection success, and screened variables to establish a prediction model. We determined the optimal cutoff value of peripheral blood markers for predicting successful stem cell collection and the clinical value of a multi-marker prediction approach. We also established a prediction model for collection efficacy. Univariate and multivariate logistic regression analyses showed that the mobilization regimen, Mono, PLT, mononuclear cell count (MNC), and peripheral blood CD34+ cell count (PB CD34+ counts) were significant predictors of successful collection of peripheral blood stem cells (PBSC). Two predictive models were constructed based on the results of multivariate logistic analyses. Model 1 included the mobilization regimen, Mono, PLT, and MNC, whereas Model 2 included the mobilization regimen, Mono, PLT, MNC, and PB CD34+ counts. Receiver operating characteristic (ROC) curve analysis showed that the PB CD34+ counts, Model 1, and Model 2 could predict successful HSCs collection, with cutoff values of 26.92 × 106/L, 0.548, and 0.355, respectively. Model 1 could predict successful HSCs collection with a sensitivity of 84.62%, specificity of 75.73%, and area under the curve (AUC) of 0.863. Model 2 could predict successful HSCs collection with a sensitivity of 83.52%, specificity of 94.17%, and AUC of 0.946; thus, it was superior to the PB CD34+ counts alone. Our findings suggest that the combination of the mobilization regimen, Mono, PLT, MNC, and PB CD34+ counts before collection has predictive value for the efficacy of autologous HSCs collection in patients with MM and lymphoma. Using models based on these predictive markers may help to avoid over-collection and improve patient outcomes.

Plerixafor for pathogen-agnostic treatment in murine thigh infection and zebrafish sepsis.

Plerixafor is a CXCR4 antagonist approved in 2008 by the FDA for hematopoietic stem cell collection. Subsequently, plerixafor has shown promise as a potential pathogen-agnostic immunomodulator in a variety of preclinical animal models. Additionally, investigator-led studies demonstrated plerixafor prevents viral and bacterial infections in patients with WHIM syndrome, a rare immunodeficiency with aberrant CXCR4 signaling. Here, we investigated whether plerixafor could be repurposed to treat sepsis or severe wound infections, either alone or as an adjunct therapy. In a Pseudomonas aeruginosa lipopolysaccharide (LPS)-induced zebrafish sepsis model, plerixafor reduced sepsis mortality and morbidity assessed by tail edema. There was a U-shaped response curve with the greatest effect seen at 0.1 μM concentration. We used Acinetobacter baumannii infection in a neutropenic murine thigh infection model. Plerixafor did not show reduced bacterial growth at 24 h in the mouse thigh model, nor did it amplify the effects of a rifampin antibiotic therapy, in varying regimens. While plerixafor did not mitigate or treat bacterial wound infections in mice, it did reduce sepsis mortality in zebra fish. The observed mortality reduction in our LPS model of zebrafish was consistent with prior research demonstrating a mortality benefit in a murine model of sepsis. However, based on our results, plerixafor is unlikely to be successful as an adjunct therapy for wound infections. Further research is needed to better define the scope of plerixafor as a pathogen-agnostic therapy. Future directions may include the use of longer acting CXCR4 antagonists, biased CXCR4 signaling, and optimization of animal models.

ОЦЕНКА БЕЗОПАСНОСТИ И ЭФФЕКТИВНОСТИ МЕТОДИКИ МОБИЛИЗАЦИИ И СБОРА ГЕМОПОЭТИЧЕСКИХ СТВОЛОВЫХ КЛЕТОК У ДЕТЕЙ РАЗНЫХ ВОЗРАСТНЫХ ГРУПП СО ЗЛОКАЧЕСТВЕННЫМИ НОВООБРАЗОВАНИЯМИ: ОПЫТ ОДНОГО ЦЕНТРА

High dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT) is used currently as a consolidating stage in cancer treatment protocols for children from different age groups with various malignant neoplasms. Auto-HSCT can improve both progression-free survival and overall survival of such patients. At the same time the optimization of the collection of autologous hematopoietic stem cells (HSCs) seems to be an important factor in the successful implementation of auto-HSCT. The purpose of this research was to evaluate the safety and effectiveness of the HSCs mobilization and collection method in children from different age groups with various malignancies. Materials and methods used: a single-center retrospective cohort study of 258 pediatric patients (median body weight 20.0 [13.8; 42.0] (7.0-95.0) kg and median height 116 [97; 155] (55.0-189) cm) with various cancers aged 1 to 18 y/o (median 78.0 [36; 144] (3-215) months old) who received treatment in Jan. 2020-Jan. 2023 at the Research Institute of Pediatric Oncology and Hematology named after Academician L.A. Durnov with the N.N. Blokhin Russian Cancer Research Center (Moscow, Russia). Patients were divided into 3 age groups: younger than 1 y/o, 1 to 10 y/o and 11 to 18 y/o. Results: 242 (93.8%) of HSC apheresis procedures were successful on the first attempt, 16 patients underwent repeated apheresis (a total of 274 procedures were performed). The median number of CD34+ cells obtained was 110.95 [45.6; 276.4] (0.70-2338.2) cells/µl, median apheresis duration was 253.5 [189; 338] (82-575) min. No serious complications were observed during the HSCs mobilization and collection in any patient. None of the patients developed hemodynamic disturbances. The main criteria for effectiveness was the CD34+/kg level, the median of which was 5.1 [2.4; 12.7] (0.01-95.6)•106. One of the safety criteria for the patients from all the three age groups was the absence of hemodynamic disorders and citrate reactions in the form of numbness, cyanosis of the skin and respiratory disorders. Another important safety criteria were the absence of a significant decrease in both platelet and hemoglobin levels. The median platelet levels prior to the procedure was 125.5 [68; 210] (14.0-815)•109/l and 129 [73; 210] (17.0-823)•109/l at the end of the procedure (p&lt;0.001). Hemoglobin levels before and after the procedure were 100 [94; 110] (75-242) g/l and 99 [93; 109] (70-142) g/l, respectively (p&lt;0.001). Considering it safe to reduce hemoglobin (g/l) and/or platelets (•109/l) by no more than 10 units in each measurement, in 87.6±4.1% (83.0-91.1) of observed cases the procedure was safe without statistically significant differences in all age groups. The effectiveness of the HSCs mobilization and collection method proposed by the Authors in children of the older age group (11 to 18 y/o) was the lowest and was statistically significantly different from the effectiveness in the group of children aged 1 to 10 y/o (p&lt;0.001) with cancer and amounted to 84.5±4.4% (79.6-88.4). Conclusion: with the multidisciplinary team of practitioners, HSC apheresis in children is a safe and effective technique used as part of the complex cancer treatment in patients from poor prognosis groups. The apheresis algorithm that the Authors have proposed allows high-quality collection of CD34+ positive cells in amounts sufficient for further auto-HSCT.

Impact of the Addition of Daratumumab to the Standard Bortezomib-Thalidomide-Dexamethasone Regimen on Hematopoietic Stem Cell Mobilization and Collection, Post-Transplant Engraftment and Infectious Complications: A Case-Control Multicentre Real-Life Analysis.

Impact of the Addition of Daratumumab to the Standard Bortezomib-Thalidomide-Dexamethasone Regimen on Hematopoietic Stem Cell Mobilization and Collection, Post-Transplant Engraftment and Infectious Complications: A Case-Control Multicentre Real-Life Analysis.

Evaluation of blood cell count using an automatic hematology analyzer to optimize collection of peripheral blood progenitor cells by leukapheresis

BackgroundAutologous stem cell transplantation is a treatment modality for several diseases. Prediction of successful mobilization may be useful to optimize hematopoietic stem cell collection. Study design and methodsThis was a retrospective study with data from transplantation candidates between September 2015 and December 2021 being analyzed. The medical record of each patient was reviewed to mine mobilization information. The laboratory data analyzed were CD34+ cell enumeration and pre-collection peripheral blood cell count. The primary outcome, good mobilization, was defined as a CD34+ cell count ≥20/μL. ResultsThis study included 807 patients. Increased patient weight, low mean corpuscular volume, high nucleated red blood cells, peripheral blood mononuclear cell and immature granulocyte counts were significantly associated with good mobilization. In addition, patients diagnosed with multiple myeloma were two times more likely to be good mobilizers than patients with lymphoma. The model was applied to a validation set to identify patients who underwent apheresis (CD34+ cell count ≥10 µL), resulting in a sensitivity of 69 %, a specificity of 95 %, positive predictive value of 98 %, and a negative predictive value of 50 %. ConclusionSuccess in mobilization was greater in patients who underwent the first mobilization cycle and who had a diagnosis of multiple myeloma. Furthermore, higher body weight, and nucleated red blood cells, immature granulocytes and mononuclear cell counts, as well as low mean corpuscular volumes, were associated with successful mobilization.

Effect of prior lenalidomide or daratumumab exposure on hematopoietic stem cell collection and reconstitution in multiple myeloma.

The roles of Lenalidomide (Len) and Daratumumab (Dara) in multiple myeloma treatment are well-established, yet their influences on hematopoietic stem cell harvesting and reconstitution remain disputed. We conducted a systematic database review to identify cohort studies or RCTs evaluating the effect of the use of Len or Dara on hematopoietic stem cell collection and peripheral blood count recovery in multiple myeloma patients. Effects on hematopoietic collection or reconstitution were estimated by comparing standardized mean differences (SMD) and mean differences (MD), or median differences. Eighteen relevant studies were identified, summarizing mobilization results. For Len, data from 13 studies were summarized, including total CD34+ cell yield, collection failure rate, and time to neutrophil and platelet engraftment. Results indicated that Len exposure led to decreased stem cell collection [SMD=-0.23, 95% CI (-0.34, -0.12)]. However, collection failure (<2×106) could be mitigated by plerixafor [OR=2.14, 95% CI (0.96, 4.77)]. For Dara, two RCTs and three cohort studies were included, showing that Dara exposure resulted in a reduction in total stem cells even with optimized plerixafor mobilization [SMD=-0.75, 95% CI (-1.26, -0.23)], and delayed platelet engraftment recovery [MD=1.20, 95% CI (0.73, 1.66)]. Our meta-analysis offers a comprehensive view of Len and Dara's impacts on hematopoietic stem cell collection and reconstitution in multiple myeloma. Len usage could lead to reduced stem cell collection, counteracted by plerixafor mobilization. Dara usage could result in diminished stem cell collection and delayed platelet engraftment.

Motixafortide Enables Consistent, Robust Hematopoietic Stem Cell Collection (HSC) across Populations with Increased Impaired HSC Mobilization: A Sub-Group Analysis of the Genesis Study

Motixafortide Enables Consistent, Robust Hematopoietic Stem Cell Collection (HSC) across Populations with Increased Impaired HSC Mobilization: A Sub-Group Analysis of the Genesis Study

Effect of voxelotor on murine bone marrow and peripheral blood with hematopoietic progenitor cell mobilization for gene therapy of sickle cell disease

In preparation for hematopoietic stem cell mobilization and collection, current ex vivo gene therapy protocols for sickle cell disease require patients to undergo several months of chronic red cell transfusion. For health care equity, alternatives to red cell transfusion should be available. We examined whether treatment with GBT1118, the murine analog of voxelotor, could be a safe and feasible alternative to red cell transfusion. We found that 3 weeks of treatment with GBT1118 increased the percentage of bone marrow hematopoietic stem cells and upon plerixafor mobilization, the percentage of peripheral blood hematopoietic stem cells. Our data suggest that voxelotor should be further explored for its potential safety and utility as preparation for hematopoietic stem cell mobilization and collection.

The Italian registry of therapeutic apheresis in SISTRA: Year of activity 2022

Therapeutic apheresis refers to a group of extracorporeal blood processing procedures used in the treatment of a variety of systemic diseases. These complex procedures are burdened by adverse reactions related to both procedures and underlying medical conditions.Given the importance of centralizing the collection and the analysis of information on therapeutic apheresis, the Italian National Blood Center (NBC), at the request of the Italian Scientific Society of Hemapheresis and Cell Manipulation (SIdEM), implemented the Italian Registry of Therapeutic Apheresis (IRTA) including it in the Information System of Transfusion Services (SISTRA), coordinated by the NBC.In 2022, a total of 34,702 therapeutic apheresis procedures was carried out in 8,781 patients, including paediatric patients, with an average of 3.9 procedures per patient. The 2022 IRTA data indicate that the patient with hematological and/or neurological disorders mainly turns to the apheresis centers. These results confirm the IRTA data from years 2020 and 2021. In the hematological field, the apheresis centers supply hematopoietic stem cells collection for autologous transplantation as well as mononuclear cell collection for extracorporeal photopheresis. With regard to the neurological field, myasthenia, chronic inflammatory demyelinating polyneuropathy and Guillain-Barré syndrome along with other neurological pathologies related to immune disorders are the most treated.In conclusion, this manuscript presents 2022 activity data of IRTA providing institutions and scientific societies with a wide range of information including type and number of therapeutic procedures, adverse events and patients’ outcome.

Comparison of Various Stem Cell Mobilization Regimens for Multiple Myeloma - a 15-Year Retrospective Institutional Analysis from India

Introduction For multiple myeloma (MM), Cyclophosphamide (Cy) based chemo-mobilization offers advantage in term of higher stem cell yield and can overcome adverse impact of prior lenalidomide therapy on stem cell harvest. However, considering need for hospital stay and risk of febrile neutropenia, steady state mobilization with G-CSF and pre-emptive plerixafor (PEF) is becoming increasingly popular. Until few years back, cost of PEF was prohibitive thereby limiting its use and prompting a search for alternative cheaper drugs. Mouse models have shown that Proteasome Inhibitors aid in hematopoietic stem-cell (HSC) mobilization by down-regulating very-late antigen-4 (VLA-4) on bone marrow stromal cells which interacts with vascular cell adhesion molecule (VCAM-1) on HSC. We previously reported that bortezomib (Bort) in combination with Cy-G-CSF showed a trend towards higher CD34 yield and reduced need for apheresis sessions, without additional toxicity. There is limited data comparing mobilization regimens, especially from low-middle income countries where HSC collection may not be done after 4-6 cycles of first-line therapy. We hereby report our 15-year experience of various mobilization regimens for MM. Methods All patients with MM who underwent HSC mobilization from September 2007 - December 2022 were included in this analysis. Various mobilization regimens [Group 1 - G-CSF + Bort (August 2018 - December 2022); Group 2 - G-CSF + plerixafor (August 2018 - December 2022); Group 3 - Bort-Cy-GCSF (April 2016 - July 2018); Group 4 - Cy + G-CSF (September 2007 - March 2016)] were used as per respective time-periods (Table 1). Our aim was to collect CD34 cell dose of 5million/kg to suffice for 2 transplants. G-CSF (5 mcg/kg subcutaneously BD) was given on days 1-5 (Groups 1 and 2). Bort (1.3mg/m 2 iv / sc) (Group 1) or PEF (Group 2) were given on day 4 twelve hours prior to planned apheresis on day 5. Apheresis was done on day 5, and additionally on day 6, if first harvest was inadequate for 2 transplants. In group 3, Bort (1.3mg/m 2 iv) was given on days-1,4,8,11, with Cy (1gm/m 2 iv) on days 8 and 9, followed by G-CSF from day 11 onwards. Cy (1gm/m 2 iv) was given on day 1 and 2 (Group 4), followed by G-CSF from day 4 onwards. Stem cell harvest was done in groups 3 and 4 once peripheral blood CD34 (PB CD34) was &amp;gt;20/µL. In groups 3 and 4, if PB CD34 was &amp;lt;20/µL for 2 subsequent days, PEF was used according to physician's discretion, if available. Similarly in Group 1, if PB CD34 was between 10-20/µl on day 4, PEF was used according to physician's discretion. PEF was used in any group after the first harvest if the cell dose was deemed inadequate, at physician's discretion. Primary objective was to determine proportion of patients with CD34 + dose ≥5x10 6/kg in first apheresis in various groups. Secondary objectives were to determine total median CD34 + dose (x10 6/kg) collected, median CD34 + (x10 6/kg) in first apheresis, and frequency of mobilization failure. Mobilization failure was defined as total collected CD34 + dose of &amp;lt;2x10 6/kg or abandoned harvest attempt anticipating a poor collection.Analysis was done as per planned regimen (intention to treat analysis). Results Total 205 patients were analyzed. Median age was 48 years (27-65 years) and 143 (70%) were males (Table 1). Median day of first collection in groups 3 and 4 was day10 from the first dose of cyclophosphamide. Percentage of patients who collected ≥5x10 6 CD34 + cells/kg in first apheresis were 26%, 53%, 69% and 63%, respectively in Groups 1-4 (p=0.0001) (Table 1). CD34+ cell-dose in first apheresis and total dose collected are shown in Table 1. In comparison to groups 1 and 2, both chemo-mobilization groups (group 3 and 4) had a significantly higher total cell dose (Figure 1). In comparison to group 1, both Cy chemo-mobilization groups had a significantly higher cell dose in first harvest, but there was no significant difference between group 2 and group 4 (p=0.23) (Figure 1). PEF was required additionally in 47%, 22%, and 7% of patients in groups 1, 3 and 4 respectively (P&amp;lt;0.00001). Amongst transplanted patients, there was no difference in neutrophil or platelet engraftment and the frequency of engraftment syndrome in various groups. Conclusion Cy-based chemo-mobilization regimens have advantage of higher total stem cell yield, while they are equivalent to G-CSF + Plerixafor for harvest in single apheresis. Addition of Bortezomib to Cyclophosphamide may help to increase stem cell yield.

Improvement in Iron Burden in Patients with Transfusion-Dependent β-Thalassemia (TDT) Treated with Betibeglogene Autotemcel (Beti-cel) Gene Therapy: Up to 9 Years of Follow-up

Introduction: Beti-cel is an approved, one-time gene therapy treatment for adult and pediatric patients with TDT. Beti-cel consists of autologous hematopoietic stem and progenitor cells transduced with the BB305 lentiviral vector encoding a modified β-globin gene (β A-T87Q), which produces functional hemoglobin (Hb) and addresses the underlying genetic cause of TDT. While transfusion independence (TI) remains a critical component for assessing patient response to gene therapy, other measures, including markers of iron overload, are important for evaluating the impact of therapy and management of disease burden over time. Previously, we demonstrated that iron markers stabilized in patients who achieved TI and stopped chelation therapy. Here, we report iron management outcomes in patients who completed either a phase 1/2 or phase 3 beti-cel parent study and subsequently enrolled in the long-term follow-up study. Methods: Patients with TDT who completed a parent beti-cel study (phase 1/2 studies: HGB-204 [NCT01745120]; HGB-205 [NCT02151526]; phase 3 studies: HGB-207 [NCT02906202]; HGB-212 [NCT03207009]) could enroll in a long-term study (LTF-303 [NCT02633943]) for up to an additional 13 years of follow-up. In these studies, TI was defined as a weighted average Hb ≥9 g/dL without packed red blood cell transfusions for ≥12 months. Iron removal therapy was at the discretion of the treating physician. Liver and cardiac magnetic resonance imaging evaluated liver iron concentration (LIC) and cardiac T2*; serum ferritin and transferrin receptor (TfR) were assessed at regular intervals according to protocol. Results:As of January 30, 2023, 63 patients received beti-cel; median (range) follow-up was 60.1 (23.8-109.5) months. In phase 3 studies, 37/41 (90%) patients achieved TI and maintained TI through the last follow-up, which was 5+ years for 10 patients ( Figure 1). In phase 1/2 studies, 15/22 (68%) patients achieved TI; 14 of these patients maintained TI through the last follow-up, which was up to 9 years. One patient no longer meets protocol-defined TI as a result of Hb level &amp;lt;9g/dL at year 6 due to acute health events unrelated to β-thalassemia, which were not attributed to loss of beti-cel treatment effect. In total, 51 patients across phase 1/2 and 3 studies achieved and maintained TI through last follow-up with 35/51 (69%) patients off chelation. Thirty of 51 patients had an LIC measurement at month 48. Of these 30 patients, 21 had an LIC &amp;lt;5 mg/g at month 48 post infusion. Among these 21 patients, 5 never restarted chelation after infusion (2 received phlebotomy only), 11 restarted chelation and then were able to discontinue after iron stores normalized (1 also received phlebotomy), and 5 continue to receive chelation (none had phlebotomy). The other 9 patients who had an LIC measurement at month 48 had an iron burden ≥5 mg/g. All 9 of these patients restarted chelation; 4 were able to discontinue (2 had phlebotomy) and 5 continue to receive chelation (1 had phlebotomy). Analysis of iron marker stabilization after discontinuation of chelation will be presented. The median (range) change from baseline in LIC levels at month 48 was -3.9 (-22.3 to 10.5) mg Fe/g dry weight; the median (range) change from baseline in serum ferritin was -2119.0 (-7211 to 3889) pmoL/L. Reductions from baseline in serum TfR were observed at month 36; cardiac T2* remained stable at month 48 ( Table 1). Safety of beti-cel treatment largely reflected the known side effects of hematopoietic stem cell collection and the busulfan conditioning regimen. Conclusion: In this analysis with up to 9 years of follow up, patients treated with beti-cel who achieved TI also demonstrated sustained improvements in iron burden, and the majority of patients were able to stop chelation. Collectively, these results demonstrate the long-term durability and stability of response after beti-cel gene therapy in patients with TDT.

A prospective, multicenter study on hematopoietic stemcell mobilization with cyclophosphamide plus granulocyte colony-stimulating factor and 'on-demand' plerixafor in multiple myeloma patients treated with novel agents.

High-dose melphalan plus autologous stem cell transplantation (ASCT) is a standard of care for transplant-eligible patients with newly diagnosed multiple myeloma (NDMM), and adequate hematopoietic stem cell (HSC) collection is crucial to ensure hematologic recovery after ASCT. In this prospective, observational study we evaluated HSC mobilization with granulocyte colony-stimulating factor (G-CSF), cyclophosphamide, and 'on-demand' plerixafor (in patients with <20×106 CD34+ cells/L after at least 4 days of G-CSF or failing to collect ≥1×106 CD34+ cells/kg after the first apheresis) in NDMM patients treated with novel agent-based induction therapy. The primary endpoint was the rate of poor mobilizers (patients collecting <2×106 CD34+ cells/kg or requiring plerixafor rescue to reach an adequate HSC harvest). Secondary endpoints included the rate of patients collecting ≥2×106 CD34+ cells/kg after plerixafor administration and the identification of factors predicting mobilization failure or plerixafor need. Overall, 301 patients (median age 60 years) were enrolled. Two hundred and eighty-seven of 301 (95%) and 274 of 301 (93%) patients collected ≥2×106 and ≥4×106 CD34+ cells/kg, respectively, with a median of 9.9×106 CD34+ cells/kg collected. Poor mobilizers were 48 of 301 (16%): 34 of 301 (11%) required plerixafor rescue, and 14 of 301 (5%) failed HSC collection regardless of plerixafor. Thirty-four of 38 (90%) patients receiving plerixafor collected ≥2×106 CD34+ cells/kg. Bone marrow plasmacytosis at diagnosis >60% (odds ratio [OR]=4.14), lenalidomide use (OR=4.45), and grade 3-4 hematologic toxicities during induction (OR=3.53) were independently associated with a higher risk of mobilization failure or plerixafor need. Cyclophosphamide plus G-CSF and 'on-demand' plerixafor is an effective strategy in NDMM patients treated with novel agents, resulting in a high rate of HSC collection and high HSC yield (clinicaltrials gov. identifier: NCT03406091).

Comparison of different plerixafor-based strategies for adequate hematopoietic stem cell collection in poor mobilizers

Objectives: The main objective of the present study was to evaluate whether the use of plerixafor in combination with granulocyte colony-stimulating factor (G-CSF) or subsequent use of isolated G-CSF and then plerixafor following disease-specific chemotherapy, and whether it would allow for adequate peripheral stem cell collection in patients. Methods: The retrospective study evaluated 54 patients with previous mobilization failure who were administered plerixafor in 2 centers. In patients without any side effects, CD 34+ cell counts, the percentage of patients who were found eligible for autologous transplantation, the engraftment kinetics of the patients who underwent transplantation, and their overall survival results were compared between the two groups where G-CSF was used with plerixafor, or where plerixafor was used after isolated G-CSF following chemotherapy. Results: The median age of the patients was 49 years (range: 17-70), and 64.8% (n = 35) were males. It was identified that 31 (57.4%) patients underwent mobilization treatment with isolated G-CSF and plerixafor, and 23 (42.6%) patients underwent mobilization treatment with chemotherapy plus G-CSF and plerixafor. In all patients, mean hemoglobin level (11.3 ± 1.5 g/dL vs. 9.3 ± 1.3 g/dL; p &amp;lt; 0.001) and median platelet level (129.2 ×103/µL vs. 58.4 ×103/µL) were found to be higher, while febrile neutropenia rate (3.3% vs. 60.9%), the percentage of replacement patients (6.7% vs. 65.2%), and median days of G-CSF (6 vs. 9) were found to be lower on the day of plerixafor administration in the isolated G-CSF and plerixafor group compared to the chemotherapy and G-CSF and plerixafor group. Conclusions: In conclusion, our study demonstrated that administration of plerixafor is generally safe and well-tolerated. Regardless of the underlying disease, it offers an effective alternative for patients with previous failed mobilization attempts using conventional regimens, and allows stem cell collection with fewer apheresis sessions.