Hematopoietic Stem Cell Mobilization Research Articles

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 Analy

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 Analy

Interference of daratumumab and efficacy of plerixafor on haematopoietic stem cell collection in Multiple Myeloma

The impact of daratumumab on CD34+ hematopoietic stem cell (HSC) mobilization has recently been a matter of concern. To address this issue, we compared CD34+ HSC-related outcomes in patients with multiple myeloma treated with daratumumab-based quadruplets (N = 44) and bortezomib/thalidomide/dexamethasone (N = 50) before cyclophosphamide-based mobilization. Plerixafor was more often required in the daratumumab group (52% vs. 20%, p = 0.002) and, despite a lower total yield, retained its efficacy in boosting HSC harvesting (+90% vs. +79%, p = 0.463). As a result, the same proportion of patients reached their planned collection goal in the two groups, suggesting its potential to overcome the interference of daratumumab on HSC mobilization. No clinically significant differences were observed in the immediate post-autologous HSC transplant interval in the two groups.

Survivors of polymicrobial sepsis are refractory to G-CSF-induced emergency myelopoiesis and hematopoietic stem and progenitor cell mobilization

Sepsis survivors exhibit immune dysfunction, hematological changes, and increased risk of infection. The long-term impacts of sepsis on hematopoiesis were analyzed using a surgical model of murine sepsis, resulting in 50% survival. During acute disease, phenotypic hematopoietic stem and progenitor cells (HSPCs) were reduced in the bone marrow (BM), concomitant with increased myeloid colony-forming units and extramedullary hematopoiesis. Upon recovery, BM HSPCs were increased and exhibited normal function in the context of transplantation. To evaluate hematopoietic responses in sepsis survivors, we treated recovered sham and cecal ligation and puncture mice with a mobilizing regimen of granulocyte colony-stimulating factor (G-CSF) at day 20 post-surgery. Sepsis survivors failed to undergo emergency myelopoiesis and HSPC mobilization in response to G-CSF administration. G-CSF is produced in response to acute infection and injury to expedite the production of innate immune cells; therefore, our findings contribute to a new understanding of how sepsis predisposes to subsequent infection.

Comparison of two autologous hematopoietic stem cell mobilization strategies in patients with multiple myeloma: CE plus G-CSF versus G-CSF only: A single-center retrospective analysis.

Despite recent advances in the treatment of multiple myeloma, high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (ASCT) remains an essential therapeutic keystone. As for the stem cell mobilization procedure, different regimens have been established, usually consisting of a cycle of chemotherapy followed by application of granulocyte-colony stimulating factor (G-CSF), although febrile neutropenia is a common complication. Following national guidelines, our institution decided to primarily use G-CSF only mobilization during the COVID-19 pandemic to minimize the patients' risk of infection and to reduce the burden on the health system. In this retrospective single-center analysis, the efficacy and safety of G-CSF only mobilization was evaluated and compared to a historic control cohort undergoing chemotherapy-based mobilization by cyclophosphamide and etoposide (CE) plus G-CSF. Although G-CSF only was associated with a higher need for plerixafor administration (p < .0001) and a higher number of apheresis sessions per patient (p = .0002), we were able to collect the target dose of hematopoietic stem cells in the majority of our patients. CE mobilization achieved higher hematopoietic stem cell yields (p = .0015) and shorter apheresis sessions (p < .0001) yet was accompanied by an increased risk of febrile neutropenia (p < .0001). There was no difference in engraftment after ASCT. G-CSF only mobilization is a useful option in selected patients with comorbidities and an increased risk of serious infections, especially in the wintertime or in future pandemics.

Clinical Analysis of PEG-rhG-CSF in Mobilization of Autologous Hematopoietic Stem Cells in Hematological Tumors

To investigate the efficiency and optimal time of stem cell apheresis mobilized by pegylated recombinant human granulocyte colony stimulating factor (PEG-rhG-CSF) in autologous stem cell transplantation (ASCT) for hematological malignancies without monitoring pre-collection CD34+ cells. Forty-six patients underwent stem cell mobilization were retrospectively analyzed between August 2017 and January 2022 at the First Affiliated Hospital of Fujian Medical University. 27 patients using high dose chemotherapy combined with PEG-rhG-CSF mobilization were enrolled in the PEG-rhG-CSF group, and other 19 patients mobilized with recombinant human granulocyte colony stimulating factor (G-CSF) were enrolled in G-CSF group. The mobilization and collection effects of the patients in two groups were compared. A total of 46 patients underwent 86 apheresis procedures, the median amount of mononuclear cell (MNC) in the PEG-rhG-CSF group and G-CSF group was 6.54（3.85-12.61）×108/kg and 6.15（1.13-11.58）×108/kg, respectively (P >0.05), the total CD34+ cells of the grafts were 11.44(1.33-65.02)×106/kg and 4.95(0.30-24.02)×106/kg (P < 0.05), with harvest timing of 14(10-20) days and 14(4-22) days, respectively (P >0.05). In the PEG-rhG-CSF group, there was a significant difference between the number of CD34+ cells collected when white blood cells (WBC) ≥10×109/L and WBC<10×109 /L, 19.04(2.85-65.02)×106/kg and 6.22(0.81-34.86)×106/kg, respectively (P < 0.05). Stem cells mobilization with PEG-rhG-CSF was highly efficient with a median mobilization time of 14 days. In the absence of peripheral blood CD34 monitoring, peripheral blood WBC≥10×109/L can be considered as a threshold for a single stem cell apheresis to collect sufficient stem cells.

Abstract 732: Toward optimizing CXCR4 inhibition with beta adrenergic blockade to enhance chemotherapy response in acute myeloid leukemia

Abstract Introduction: CXCR4 is a chemokine receptor for CXCL12 that plays a critical role in homing of hematopoietic stem cells (HSCs) to the bone marrow microenvironment. The CXCR4 inhibitor plerixafor is used to increase mobilization of peripheral blood stem cells in combination with filgrastim. This pathway has also been investigated for applications in hematologic malignancies such as acute myeloid leukemia (AML), including clinical trials, with the goal of disrupting AML from the protective marrow environment. These have included use of plerixafor with 7+3 or MEC, BL-8040 with cytarabine, and ulocuplumab with MEC. For the ulocuplumab trial, at the study site of the authors, CR/CRi correlated with &amp;gt;10% CXCR4 expression (Becker et al. ASH 2014). The objective of this preclinical study is to identify the AML patient population most likely to respond to CXCR4 inhibition, and the role of combined beta-adrenergic blockade, as the latter has been shown pre-clinically to augment mobilization of HSCs when combined with a CXCR4 inhibitor, GPC-100 (Sukhtankar et al. PLoS One, 2023). Procedures: AML patient samples (N=124 including 90 blood and 34 bone marrow samples, and 21 with both) were obtained with informed consent on an IRB approved protocol. Multicolor flow cytometry was performed with sequential gating on blasts (by FSC/SSC, CD45/SSC, CD34 or phenotype), and leukemia stem cells (LSCs:CD34+CD38−,CD123+), then analysis for CXCR4 and beta-2 adrenergic receptor (ADRB2) surface expression. Correlations between CXCR4 expression and clinical characteristics including age, gender, new diagnosis vs. relapse, ELN2022 risk, cytogenetics, FLT3/NPM1 mutation status, CR1 duration, and overall survival were performed. GraphPad Prism9 was used for statistical analysis, and Mann Whitney test (two groups) and ordinary one-way ANOVA (&amp;gt;2 groups) were used for comparisons. Results: The range of CXCR4 expression by AML blasts is 0.05 to 99.7% (median 13.1%; mean 16.2%), and by AML LSCs 0 to 99% (median 2%, mean 15.7%). The expression by blasts and LSCs for each patient exhibited tight correlation, R2=0.88 p=1.23 × 10e-25). There was higher % expression of CXCR4 by both blasts and LSCs for new diagnosis, as compared to relapsed, patient samples (p=0.002). There was no correlation between level of CXCR4 expression and the other clinical features. For a subset of 20 patient samples analyzed for both CXCR4 and ADBR2 expression by AML blasts, ADBR2 expression ranged from 0.4 to 20.1%. For the samples that express ADBR2, there was high level expression of CXCR4, range 35.9 to 98.7% (median 78.4%, mean 76%). Conclusion: These studies support further investigation of whether simultaneous blockade of CXCR4 and ADBR2 may potentiate chemotherapy response in AML by limiting microenvironment mediated chemotherapy protection and reveal that patients with new diagnosis may be more susceptible to this approach. Citation Format: Brenda Loera, Chunxiao Zhang, Pina M. Cardarelli, Niña G. Caculitan, Sylvia Chien, Jin Dai, Vivian G. Oehler, Jianying Zhang, Guido Marcucci, Pamela S. Becker. Toward optimizing CXCR4 inhibition with beta adrenergic blockade to enhance chemotherapy response in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 732.

G-CSF + plerixafor versus G-CSF alone mobilized hematopoietic stem cells in patients with multiple myeloma and lymphoma: a systematic review and meta-analysis

Aim The combination of granulocyte-colony stimulating factor (G-CSF) and plerixafor is one of the approaches for hematopoietic stem cell mobilization in patients with multiple myeloma (MM), non-Hodgkin’s lymphoma (NHL), and Hodgkin’s lymphoma (HL). This systematic review and meta-analysis aimed to determine the ability of G-CSF + plerixafor to mobilize peripheral blood (PB) CD34+ cells and examine its safety profile. Methods We performed a database search using the terms ‘granulocyte colony stimulating factor’, ‘G-CSF’, ‘AMD3100’, and ‘plerixafor’, published up to May 1, 2023. The methodology is described in further detail in the PROSPERO database (CRD42023425760). Results Twenty-three studies were included in this systematic review and meta-analysis. G-CSF + plerixafor resulted in more patients achieving the predetermined apheresis yield of CD34+ cells than G-CSF alone (OR, 5.33; 95%, 4.34–6.55). It was further discovered that G-CSF + plerixafor could mobilize more CD34+ cells into PB, which was beneficial for the next transplantation in both randomized controlled (MD, 18.30; 95%, 8.74–27.85) and single-arm (MD, 20.67; 95%, 14.34–27.00) trials. Furthermore, G-CSF + plerixafor did not cause more treatment emergent adverse events than G-CSF alone (OR, 1.25; 95%, 0.87–1.80). Conclusions This study suggests that the combination of G-CSF and plerixafor, resulted in more patients with MM, NHL, and HL, achieving the predetermined apheresis yield of CD34+ cells, which is related to the more effective mobilization of CD34+ cells into PB.

Comparative Efficacy of Autologous Hematopoietic Stem Cell Mobilization Regimens in Multiple Myeloma Patients

Aim. To compare the efficacy of mobilization regimens (MR) differing in their composition and intensity, with the purpose of defining the criteria to personalize the choice of MR based on clinical and hematological characteristics of multiple myeloma (MM) patients.&#x0D; Materials &amp; Methods. A retrospective analysis of the autologous hematopoietic stem cell (HSC) mobilization and autograft harvesting results was performed in 177 patients with newly diagnosed MM. The patients were divided into 4 groups. Group 1 included 62 patients with the median age of 53 years who were treated with single injection of cyclophosphamide (CF) dose 3 g/m2 as MR. Group 2 consisted of 71 patients with the median age of 58 years who received vinorelbine 35 mg/m2. Granulocyte colony-stimulating factor (G-CSF) as a monoregimen was administered to group 3 consisting of 33 patients with the median age of 55 years. Group 4 included 11 patients with the median age of 57 years who received G-CSF enhanced by plerixafor administration. G-CSF 10 µg/kg was used as MR. In all chemomobilization cases, daily G-CSF 10 µg/kg started on Day 4 from the administration of the chemotherapy drug prescribed as MR.&#x0D; Results. In the analyzed groups, the median time from MR start to the first leukocyte apheresis session was 11, 8, 5, and 5 days, respectively. On the first leukocyte apheresis day, the median CD34+ cell collection in group 3 was significantly lower than in groups 1, 2, and 4: 2.2 × 106/kg vs. 3.79 × 106/kg, 7.22 × 106/kg, and 3.9 × 106/kg, respectively. The total CD34+ cell collection after two leukocyte apheresis sessions was also the lowest in group 3 compared with groups 1, 2, and 4: 3.22 × 106/kg vs. 5.2 × 106/kg, 4.95 × 106/kg, and 7.5 × 106/kg, respectively. In the analyzed groups, the rate of mobilization with CD34+ cell collection &lt; 2.0 × 106/kg was 6.5 %, 5.6 %, 18.2 %, and 9.1 %. The evaluation of the results in all patients showed a direct correlation of CD34+ cell collection with lenalidomide administered before autologous HSC mobilization. A significant difference in CD34+ cell collection in lenalidomide recipients vs. non-recipients was reported when vinorelbine as MR and G-CSF as monoregimen (р = 0.001 and р = 0.022, respectively) were used. No significant differences were observed either with CF or G-CSF combined with plerixafor treatment.&#x0D; Conclusion. Based on the findings, age of a MM patient, comorbidities, and prior lenalidomide administration can be regarded as key criteria for choosing one of 4 MRs.

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.

Targeting CXCR4, VLA-4, and CXCR2 for hematopoietic stem cell mobilization

Targeting CXCR4, VLA-4, and CXCR2 for hematopoietic stem cell mobilization

G-CSF–induced hematopoietic stem cell mobilization from the embryonic hematopoietic niche does not require neutrophils and macrophages

Hematopoietic stem cell transplantation requires the collection of hematopoietic cells from patients or stem cell donors. Granulocyte colony-stimulating factor (G-CSF) is widely used in the clinic to mobilize hematopoietic stem and progenitor cells (HSPCs) from the adult bone marrow niche into circulation, allowing a collection of HSPCs from the blood. The mechanism by which G-CSF acts to mobilize HSPCs is unclear, with some studies showing a direct stimulation of stem cells and others suggesting that myeloid cells are required. In this study, we developed a heat-inducible G-CSF transgenic zebrafish line to study HSPC mobilization in vivo. Live imaging of HSPCs after G-CSF induction revealed an increase in circulating HSPCs, demonstrating a successful HSPC mobilization. These mobilized HSPCs went on to prematurely colonize the kidney marrow, the adult zebrafish hematopoietic niche. We eliminated neutrophils or macrophages using a nitroreductase-based cell ablation system and found that G-CSF still mobilizes HSPCs from the niche. Our findings indicate that neutrophils and macrophages are not required for G-CSF-induced HSPC mobilization from the embryonic hematopoietic niche.

Biological and mutational analyses of CXCR4-antagonist interactions and design of new antagonistic analogs.

The chemokine receptor CXCR4 has become an attractive therapeutic target for HIV-1 infection, hematopoietic stem cell mobilization, and cancer metastasis. A wide variety of synthetic antagonists of CXCR4 have been developed and studied for a growing list of clinical applications. To compare the biological effects of different antagonists on CXCR4 functions and their common and/or distinctive molecular interactions with the receptor, we conducted head-to-head comparative cell-based biological and mutational analyses of the interactions with CXCR4 of eleven reported antagonists, including HC4319, DV3, DV1, DV1 dimer, V1, vMIP-II, CVX15, LY2510924, IT1t, AMD3100, and AMD11070 that were representative of different structural classes of D-peptides, L-peptide, natural chemokine, cyclic peptides, and small molecules. The results were rationalized by molecular modeling of CXCR4-antagonist interactions from which the common as well as different receptor binding sites of these antagonists were derived, revealing a number of important residues such as W94, D97, H113, D171, D262, and E288, mostly of negative charge. To further examine this finding, we designed and synthesized new antagonistic analogs by adding positively charged residues Arg to a D-peptide template to enhance the postulated charge-charge interactions. The newly designed analogs displayed significantly increased binding to CXCR4, which supports the notion that negatively charged residues of CXCR4 can engage in interactions with moieties of positive charge of the antagonistic ligands. The results from these mutational, modeling and new analog design studies shed new insight into the molecular mechanisms of different types of antagonists in recognizing CXCR4 and guide the development of new therapeutic agents.

Choosing the right mouse model: comparison of humanized NSG and NBSGW mice for in vivo HSC gene therapy

AbstractIn vivo hematopoietic stem cell (HSC) gene therapy is an emerging and promising area of focus in the gene therapy field. Humanized mouse models are frequently used to evaluate novel HSC gene therapy approaches. Here, we comprehensively evaluated 2 mouse strains, NSG and NBSGW. We studied human HSC engraftment in the bone marrow (BM), mobilization of BM-engrafted HSCs into circulation, in vivo transduction using vesicular stomatitis virus glycoprotein–pseudotyped lentiviral vectors (VSV-G LVs), and the expression levels of surface receptors needed for transduction of viral vectors. Our findings reveal that the NBSGW strain exhibits superior engraftment of human long-term HSCs compared with the NSG strain. However, neither model resulted in a significant increase in circulating human HSCs after mobilization. We show that time after humanization as well as human chimerism levels and platelet counts in the peripheral blood can be used as surrogates for human HSC engraftment in the BM. Furthermore, we observed low expression of the low-density lipoprotein receptor, a requirement for VSV-G LV transduction, in the human HSCs present in the murine BM. Our comprehensive characterization of humanized mouse models highlights the necessity of proper validation of the model and methods to study in vivo HSC gene therapy strategies.

Chinese expert consensus on the management of patients with hematologic malignancies infected with SARS-CoV-2.

In December 2022, the Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became dominant in China due to its high infectivity and lower mortality rate. The risk of critical illness and mortality among patients with hematologic malignancies who contracted SARS-CoV-2 was particularly high. The aim of this study was to draft a consensus to facilitate effective treatments for these patients based on the type and severity of the disease. Following the outbreak of the novel coronavirus in China, a steering committee consisting of experienced hematologists was formed by the Specialized Committee of Oncology and Microecology of the Chinese Anti-Cancer Association. The expert group drafted a consensus on the management and intervention measures for different types of hematologic malignancies based on the clinical characteristics of the Omicron variant of the SARS-CoV-2 infection, along with relevant guidelines and literature. The expert group drafted independent recommendations on several important aspects based on the epidemiology of the Omicron variant in China and the unique vulnerability of patients with hematologic malignancies. These included prophylactic vaccinations for those with hematologic malignancies, the use of plasma from blood donors who recovered from the novel coronavirus infection, the establishment of negative pressure wards, the use of steady-state mobilization of peripheral blood hematopoietic stem cells, the provision of psychological support for patients and medical staff, and a focus on maintaining a healthy intestinal microecology.

Impact of Daratumumab on Hematopoietic Stem Cell Mobilization with G-CSF and on-Demand Plerixafor in Newly-Diagnosed Multiple Myeloma Patients

Introduction Autologous stem cell transplantation (ASCT) is a standard of care for transplant eligible (TE) patients with newly diagnosed (ND) multiple myeloma (MM); therefore, an adequate hematopoietic stem cell (HSC) collection is crucial to allow patients to proceed to ASCT and ensure optimal hematologic recovery. A more frequent use of plerixafor (PLX) and lower HSC yields have been reported in patients treated with daratumumab, a backbone of induction therapy for NDMM patients. Chemotherapy-free mobilization with G-CSF and on-demand PLX is an effective mobilization strategy lacking chemotherapy-related toxicities. Here we present the results of a multicenter, retroprospective and prospective, observational study, aiming to compare the impact of daratumumab on HSC mobilization with G-CSF + on-demand PLX in patients with NDMM treated with bortezomib-thalidomide-dexamethasone (VTd) or VTd plus daratumumab (D-VTd). Methods NDMM patients undergoing a first HSC mobilization attempt with G-CSF (10 mcg/kg/day) were enrolled and observed up to 30 days after ASCT. According to its label, on-demand PLX was administered in patients with &amp;lt;20 CD34 + cells/µL after ≥ 4 days of G-CSF or in case &amp;lt;1×10 6 CD34 + cells/kg were collected on the first day of apheresis. The primary endpoint of the study was the rate of poor mobilizing patients (≤2x10 6 CD34 + cells/Kg collected or need for PLX to reach an adequate HSC harvest). Key secondary endpoints included: the rate of suboptimal (2 to 4 CD34 + cells/kg) and optimal (≥4 CD34 + cells/Kg) collection; the median number of apheresis required to obtain ≥2x10 6 CD34 + cells/Kg; the impact of daratumumab on HSC engraftment. Results A total of 190 NDMM patients (median age, 62 years) were enrolled in 2 Italian centres (IRCSS Istituto Clinico Humanitas and Città della Salute e della Scienza di Torino) and analyzed; of these, 70% (133/190) were treated with VTd and 30% (57/190) with D-VTd. The median number of induction cycles was 4 in both groups. Best response after the induction phase was at least very good partial response (VGPR) in 87/133 (65%) and 41/57 (72%) of patients treated with VTd or D-VTd, respectively (p=0.4). The median time from the end of induction to G-SCF administration was 24 days in the VTd group and 29 days in the D-VTd group (p=0.5). The rate of poor mobilizing patients was 31% (41/133) in the VTd group and 54% (31/57) in the D-VTd group (p=0.002), mainly due to a higher rate of PLX use in the D-VTd as compared to the VTd group (53% vs. 28%; p=0.001), while the rate of patients who failed HSC mobilization (≤2x10 6 CD34 + cells/kg collected) was similar in the two groups (2% vs. 3%; p=1). Despite a numerically higher median number of CD34 + cells collected in the VTd group (7.9) as compared to the D-VTd group (7.1; p=0.009), no difference in the rate of patients who collected 2-4 (5% vs. 5%; p=1) and ≥4 CD34 + cells/Kg (95% vs. 95%; p=1) was observed in the VTd and D-VTd groups, respectively. A higher median number of CD34 +/µL on the first day of count was observed in the VTd as compared to the D-VTd group (24.5 vs. 19, p=&amp;lt;0.001). Among patients who had &amp;lt;20 CD34 +/µL [32% (43/133) vs. 51% (29/57)] on the first day of count, a similar increase in the CD34 +/µL (48.5 vs. 55) was observed in the two groups after PLX administration. The median number of apheresis session needed to complete the harvestwas 1 fo the VTd group and 2 in the D-VTd group (p=0.1). Neutrophil and platelet recovery were achieved in 100% of patients with a median time to neutrophil recovery of 15 and 13 days in the VTd and D-VTd groups, respectively (p=&amp;lt;0.001) and a median time to platelet recovery of 16 and 14 days in the VTd and D-VTd groups, respectively (p=0.001). Conclusion G-CSF plus on-demand PLX for HSC mobilization demonstrated to be an effective strategy in NDMM patients treated with VTd with or without daratumumab, resulting in very low rates of mobilization failures irrespective of the use of daratumumab during induction. Despite a higher rate of patients requiring PLX for HSC collection and lower CD34 + yields, the incorporation of daratumumab as part of the induction treatment did not negatively impact the possibility to achieve an optimal HSC collection. Our results, along with the lack of chemotherapy-associated toxicity, support the use of a chemotherapy-free HSC mobilization with G-CSF and on-demand plerixafor also in patients receiving daratumumab upfront.

Hijacking of the Fibrinolytic System By B-Cell Acute Lymphoblastic Leukaemia and Its Therapeutic Targeting

The fibrinolytic system plays a role in the mobilization of hematopoietic stem cells from their bone marrow microenvironment (BMM), but its function in leukemias is not well understood. The fibrinolytic system consists of the proenzyme plasminogen and its active form, plasmin, a serine protease. The activation of plasmin is tightly regulated by activators such as tissue plasminogen activator (tPA) and various inhibitors. A role of this plasminogen activation system in the microenvironment of solid tumors is being unravelled, but a function of this pathway in the BMM, where hematological cancers usually originate, has so far been elusive. Transcriptome analysis of mesenchymal cells in the BMM of mice with different leukemias had revealed annexin A2 ( Anxa2), an initiator of fibrinolysis, to be differentially expressed. Using an ANXA2-deficient BMM as a model for impaired fibrinolysis, we showed that ANXA2 promotes the activation of plasmin, leading to decreased levels of the extracellular matrix (ECM) protein fibronectin in the BMM and accelerating the progression of BCR-ABL1 + B-cell acute lymphoblastic (B-ALL), but not MLL-AF9 + acute myeloid leukemia. Consistently, induction of B-ALL in tPA-deficient mice led to fibronectin accumulation in the BMM and significant survival prolongation. The dense ECM in an ANXA2-deficient BMM is shown to entrap insulin-like growth factor (IGF) and to specifically reduce mTORC2-dependent signalling and proliferation in B-ALL cells. Conversely, B-ALL cell-derived interleukin (IL)-6 conditions hepatic generation of plasminogen, the precursor of plasmin, perpetuating this circuit. Treatment with -aminocaproic acid (EACA), an anti-hemorrhagic drug, which inhibits plasmin activation, reduces tumor burden and prolongs survival in syngeneic and xenogeneic murine models via increased fibronectin in the BMM. Human data confirm that IGF1 and fibronectin staining in trephine biopsies are correlated and that the mTORC2 pathway is distinctly activated in B-ALL. Higher expression of SERPINF2 (α2-antiplasmin), an inhibitor of plasmin, in human B-ALL cells leads to superior outcome. In summary, B-ALL-derived IL-6 impacts hepatic generation of fibrinolytic agents influencing B-ALL progression via ECM remodeling and regulation of the availability of B-ALL-supportive growth factors. Inhibition of plasmin-mediated degradation of the ECM by EACA may be beneficial as adjunct therapy in B-ALL.

Constructing a Machine Learning-Based Rating Model to Predict the Outcome of GCSF Mobilization of Hematopoietic Stem Cells in Peripheral Blood

Objective Peripheral blood stem cells serve as the primary source of hematopoietic stem cells for both autologous and allogeneic stem cell transplantation. Granulocyte colony-stimulating factor (G-CSF) stands as the most commonly employed mobilizing agent in clinical practice. While the majority of donors receiving G-CSF mobilization demonstrate high mobilization efficiency, there remains a subset of donors who fail to yield a sufficient quantity of hematopoietic stem cells. Inefficient mobilization not only leads to wastage of valuable resources but also significantly impacts transplant outcomes for recipients. Therefore, addressing the challenges associated with predicting mobilization outcomes, optimizing donor selection strategies, and further enhancing mobilization approaches is of paramount importance. Methods In this study, we conducted a retrospective analysis of mobilization data from 1008 donors who underwent hematopoietic stem cell mobilization using G-CSF at the Bone Marrow Transplantation Center, the First Affiliated Hospital, Zhejiang University School of Medicine, over the past 5 years. We meticulously examined the correlation between mobilization outcomes (quantified by the quantity of collected CD34+ cells) and various factors, including mobilizing agent usage, demographic data, complete blood count, and blood biochemistry. Furthermore, we harnessed the power of machine learning algorithms, such as linear regression, decision tree, and AdaBoost, to develop a robust scoring model capable of predicting mobilization outcomes. The primary objective of this model is to furnish a predictive tool for assessing mobilization outcomes with accuracy and precision. Results (1) Prior to receiving G-CSF, several factors exhibited a significant positive correlation with the quantity of CD34+ cells in the collection: donor's body weight (R=0.37, p&amp;lt;0.001), peripheral blood leukocytes (R=0.24, p&amp;lt;0.001), hemoglobin (R=0.23, p&amp;lt;0.001), monocytes (R=0.22, p&amp;lt;0.001), lymphocytes (R=0.18, p&amp;lt;0.001), platelets (R=0.18, p&amp;lt;0.001), red blood cells (R=0.12, p&amp;lt;0.001), neutrophils (R=0.15, p&amp;lt;0.001), hematocrit (R=0.21, p&amp;lt;0.001), mean corpuscular-hemoglobin concentration (R=0.15, p&amp;lt;0.001), low-density lipoprotein (R=0.11, p&amp;lt;0.01), albumin (R=0.09, p&amp;lt;0.05), ferritin (R=0.19, p&amp;lt;0.001), triglycerides (R=0.17, p&amp;lt;0.001), creatinine (R=0.17, p&amp;lt;0.001), and uric acid (R=0.29, p&amp;lt;0.001). (2) Age exhibited a significant negative correlation with the quantity of collected CD34+ cells in the collection (R=-0.11, p&amp;lt;0.001). (3) When the total dose of G-CSF administration was fixed, mobilization with twice-daily dosing yielded superior results compared to once-daily dosing (collected CD34+ cell count: 1268/μl vs. 1044/μl, p&amp;lt;0.001). (4) The ratio of G-CSF dosage to body weight demonstrated a significant negative correlation with the quantity of CD34+ cells (R=-0.09, p&amp;lt;0.01). Mobilization with a ratio of 6-7 μg/kg/day showed better results compared to a ratio of 7-12 μg/kg/day (p=0.07). (5) A scoring model was developed using machine learning methods to predict the mobilization outcomes of donors. Validation on the test dataset exhibited a high predictive ability of the model (AUC&amp;gt;0.7). Conclusion This study provides valuable insights for selecting hematopoietic stem cell donors and serves as a reference for future strategies aimed at improving mobilization outcomes. The identified factors, such as donor weight, peripheral blood parameters, G-CSF dosing regimen, and the ratio of dosage to body weight, can be considered when selecting donors and optimizing mobilization protocols. By incorporating machine learning techniques, a scoring model was developed, demonstrating a high predictive ability that can assist in forecasting mobilization outcomes for potential donors. These findings contribute to the optimization of donor selection and mobilization strategies.

Incidence, Clinical Characteristics and Risk Factors for Poor Mobilization of Hematopoietic Stem Cells in a Colombian Bone Marrow Transplantation Unit: A Retrospective Cohort Study

Background: mobilized peripheral hematopoietic stem cells (PHSC) are the main cell source for autologous bone marrow transplantation. Failure to mobilize an appropriate number of PHSC can jeopardize autologous bone marrow transplantation procedure. Objective: our aim was to describe the clinical and demographics characteristics, the incidence of mobilization failure and the prevalence of risks factors for poor mobilization in patients in whom PHSC mobilization were attempted for autologous bone marrow transplantation between January 1st 2017 and 31 December 2022. A univariate and multivariate analysis (binary logistic regression) were done to determinate the association between risk factors and mobilization failure. Results: 129 patients were included , the patients median age was 54 years. Indications for autologous bone marrow transplantation were multiple myeloma in 50,4 %, lymphoma in 46,5 % and systemic sclerosis in 2,3 % of patients respectively. Mobilization was attempted with Filgrastim in 71,1 %, Filgrastim plus Plerixafor in 26,6 % and chemotherapy (Cyclophosphamide) plus Filgrastim in 2,3 % of patients respectively. Mobilization failure occurred in 9,3 % of patients (12 patients) occurring in 11 % of patients who received Filgrastim, in 5,6 % who received Filgrastim plus Plerixafor and in none of patients who received chemotherapy plus Filgrastim. No difference in mobilization failure was found between patients who received Filgrastim monotherapy versus those who received Filgrastim plus Plerixafor ( χ 2 p=0,388, relative risk: 1,8, confidence interval 95% 0,43 - 8,1). Patients who received Filgrastim plus Plerixafor had been treated more frequently (four of more cycles of Lenalidomide) compared with patients who received Filgrastim alone (63,3 % versus 18,7 %, χ 2 p &amp;lt; 0,001, RR=4,01, CI 95 %; 2,32-6,87).The median age of patients was superior in patients who received Filgrastim plus Plerixafor compared with those who received Filgrastim (58 vs 51 years, U Mann Whitney p = 0,02). The median number of treatment lines tended to be superior in patients receiving Filgrastim plus Plerixafor compared to those receiving Filgrastim (2 lines versus 1 line of therapy, U Mann Withney p= 0,054). Patients who had been treated with intensive chemotherapy regimens like DHAP, ESHAP or Hyper CVAD (p=0,004, RR: 4,3, CI 1,5-12,3)) and patients older than 60 years (p=0,018, RR: 3,4 (1,2-9,85)) were significant more prone to mobilization failure in bivariate and multivariate analysis. Conclusion: mobilization failure occurred in 9,3 % of patients , Filgrastim monotherapy was more frequently used, no difference in mobilization failure was found between those who received Filgrastim versus Filgrastim plus Plerixafor, history of treatment with more than 4 cycles of lenalidomide and older age were more frequently in patients who received Filgrastim plus Plerixafor. History of a treatment intensive chemotherapy regimen and being older than 60 years were consistently associated with mobilization failure in univariate and multivariate analysis.

The Combination of Pegfilgrastim and Filgrastim Improves the Outcomes of Mobilization and Engraftment after Transplantation of Autologous Hematopoietic Stem Cells for the Treatment of Lymphoma

BACKGROUND : Hematopoietic stem cell transplantation (HSCT) is broadly utilized for the treatment of lymphoma. Autologous peripheral blood stem cell (PBSC) transplantation (ASCT) requires mobilization of hematopoietic stem cell/ hematopoietic progenitor cell (HSC/HPC) in peripheral blood (PB) to collect HSCs. The high mobilization failure rate with the mobilization strategy of combining chemotherapy and filgrastim (rhG-CSF, recombinant human granulocyte colony-stimulating factor) in ASCT is one of the unresolved issues. Whether the combination of polyethylene glycol filgrastim [pegfilgrastim (PEG-FIL), PEG-rhG-CSF] and filgrastim (FIL) improves the mobilization success rate and the timing of combination therapy has not been studied. METHODS: To test the hypothesis that the combination of pegfilgrastim and filgrastim schedule has superiority, we retrospectively investigated a cohort of 107 lymphoma patients who received auto-HSCT and collection in the First Hospital of Jilin University from Jan 1st 2015 to Dec 1st 2022. These patients were categorized into PEG+FIL group and FIL group. The group of PEG+FIL received pegfilgrastim (9 mg) on the third day of the chemotherapy, followed by filgrastim (10 μg/kg/day) based on the counts of peripheral blood stem cells (PBSC). The group of FIL received filgrastim 10 μg /kg/day depending on the number PBSCs. Demographic information, laboratory results, and treatment plans were collected for these two groups of patients. RESULTS：We compared their mobilization efficacy (mononuclear cell [MNC] and CD34 + cell counts) and transplantation efficacy (days to leukocyte and platelet recovery post-transplantation). Successful ASCT mobilization was achieved in 93 patients (86.9%), with the PEG+FIL group exhibiting a higher success rate compared to the FIL group (89.2% [58/65] vs. 83.3% [35/42], p = 0.032). The PEG+FIL group also demonstrated significantly higher CD34+ cell counts [MNC: 8.9 (6.9, 11.2) vs. 7.8 (6.2, 9.8) × 10 8 cells/kg, p = 0.024; CD34 + cell count: 7.5 (5.6, 13.0) vs. 4.9 (3.2, 9.2) × 10 6 cells/kg, p = 0.008] and a lower incidence of neutropenic fever compared to the FIL group (11.8% vs. 24.3%, p = 0.038). The PEG+FIL group also demonstrated a shorter mean leukocyte recovery time in autologous stem cell transplantation than the FIL group (10.02 ± 0.73 vs. 10.9 ± 1.1 days, p &amp;lt; 0.001). To delve deeper into the safety considerations of both groups, we evaluated the advantages of each regimen and the methodologies for selecting time windows. A bone marrow aspiration and biopsy were performed on all patients before stem cell collection. Among 18 patients who had a hematopoietic area less than 30% and a fat area greater than 40%, 10 were in the PEG+FIL group and 8 in the FIL group. For patients who required only one collection, the durability was 80% in the PEG+FIL group compared to 0% in the FIL group (p &amp;lt; 0.01), indicating a superior recommendation for patients with a bone marrow hematopoietic area of less than 30%. In the PEG+FIL group, monitoring was carried out for PB CD34 + percentage and WBC count following pegfilgrastim administration, with subsequent computation of CD34 + cells in PB. Filgrastim administration was found to be optimal 5-6 days post-pegfilgrastim administration. CONCLUSIONS: In conclusion, relative to conventional filgrastim mobilization, the conjunctive use of pegfilgrastim and filgrastim demonstrates superior efficacy, non-inferior safety during ASCT. The schedule enhanced the the outcomes of mobilization in the patients of less hematopoietic area. KEY WORDS: Pegylated recombinant human granulocyte-stimulating factor (pegfilgrastim, PEG-rhG-CSF), recombinant human granulocyte-colony stimulating factor (filgrastim, rhG-CSF), lymphoma, hematopoietic stem cell transplantation (HSCT) autologous hematopoietic stem cell mobilization.

Targeting the JAK2V617F Hematopoietic Stem Cell through Beta1 Integrin

The major barrier to progress in treatment of primary myelofibrosis (PMF) is the lack of effective therapies targeting the malignant JAK2 V617F hematopoietic stem cell (HSC), the source of disease progression and relapse. Expression of JAK2 V617F induces abnormal proliferation and differentiation of HSC, affecting all blood lineages but most prominently the erythro-megakaryocytic lineage, leading to clonal megakaryocyte proliferation, erythrocytosis and thrombocytosis. In our previously published work ( Matsuura et al, Blood 2020) we identified elevated expression of the α5 subunit of the α5β1 integrin receptor as a driver of JAK2 V617F megakaryocyte proliferation. Expression of β1 integrin subunit was similar in wild-type (WT) and JAK2 V617F megakaryocytes, but activation of β1 integrin, detected by the conformation-specific 9EG7 antibody, was elevated in JAK2 V617F megakaryocytes. Following up on those findings, we detected elevated β1 integrin activation in long-term hematopoietic stem cells (HSC LT, LSKCD48-CD150+) from JAK2 V617F transgenic mice ( Xing et al, Blood 2008) when compared to WT controls. To determine whether inhibition of β1 integrin in vivo reduces the number of HSC LT in JAK2 V617F transgenic mice, we examined HSC LT 24 hours after intravenous administration of 2mg/Kg of anti-β1 integrin inhibitory antibody HMβ1-1. This regimen led to a sharp reduction in number and percentage of HSC LT in JAK2 V617F transgenic mice, to 45% of control antibody-treated animals. The effect on WT HSC LT was negligible. HSC ST (LSKCD48-CD150-) and MPP2 (LSKCD48+CD150+) were also reduced, but the reduction was not statistically significant. MPP3/4 (LSKCD48+CD150-) and LSK were not affected. Megakaryocyte progenitors (LKCD41+CD150+) were significantly reduced. Inhibition of β1 integrin also sharply reduced peripheral blood platelet numbers in WT animals. The reduction in JAK2 V617F transgenic mice was not statistically significant. A longer observation time of 7 days demonstrated that while WT animals were able to mount a robust regenerative response with slight but significant increases in HSC LT and normalization of platelet numbers, in JAK2 V617F transgenic mice the number of HSC LT remained depressed, as did downstream stem/progenitor populations at various significance levels. To gain insight into the mechanisms that lead to reduction in HSC LT, we examined apoptosis, cell cycle and HSC mobilization, all processes known to be affected by β1 integrin. Although basal expression of the apoptotic marker annexin V was decreased in JAK2 V617F HSC LT compared to WT, no differences were detected upon administration of HMβ1-1 in both genotypes at 4 hours post-administration. Similarly, peripheral blood colony assays revealed a basally higher level of stem/progenitor mobilization in JAK2 V617F, which did not significantly increase upon HMβ1-1 administration. In contrast, the cell cycle profile, examined at 4 hours post-administration to account for the earliest effects, demonstrated a decrease in G0 phase cells and increase in S/G2/M cells indicating cell cycle induction and exit from quiescence in both WT and JAK2 V617F HSC LT. The results indicate that inhibition of β1 integrin disrupts the adhesion-mediated cell cycle suppression in both WT and JAK2 V617F HSC LT leading to exit from quiescence. However, the downstream consequences of cell division in HSC LT differ significantly, with an apparent loss of regenerative potential in JAK2 V617F HSC LT, at least at the observed timepoints. Longer observation times are required to determine whether continuous β1 integrin inhibition can lead to JAK2 V617F HSC LT exhaustion. More sensitive assays to monitor mobilization are warranted to quantify possible minute amounts of mobilized HSC LT. Our preclinical studies indicate that β1 integrin is an attractive target to specifically reduce the number of JAK2 V617F HSC LTin vivo. The role of β1 integrin in HSC LT has not been thoroughly studied due to lack of phenotype in β1 integrin-deficient HSC ( Brakebush et al, Immunity 2002). Our studies using the anti-β1 integrin antibody in WT HSC LT confirm previous findings. However, β1 integrin seems to be critical for maintenance of JAK2 V617F HSC LT, offering a possible therapeutic window. Understanding how β1 integrin supports quiescence in HSC LT will bring us a step closer to understanding the mechanisms that drive malignancy and fitness in JAK2 V617F HSC LT.