A case of acute lung injury in a peripheral blood stem cell donor mobilized with pegylated recombinant human granulocyte colony-stimulating factor.

Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) has been introduced for the mobilization of peripheral blood stem cells (PBSCs). However, no cases of acute lung injury (ALI) in healthy donors have been reported, and the underlying mechanisms remain poorly understood. We first reported a case of ALI caused by PEG-rhG-CSF in a healthy Chinese donor, characterized by hemoptysis, hypoxemia, and patchy shadows. Ultimately, hormone administration, planned PBSC collection, leukocyte debridement, and planned PBSC collection resulted in active control of the donor's ALI. The donor's symptoms improved without any adverse effects, and the PBSC collection proceeded without incident. Over time, the lung lesion was gradually absorbed and eventually returned to normal. PEG-rhG-CSF may contribute to ALI in healthy donors via mechanisms involving neutrophil aggregation, adhesion, and the release of inflammatory mediators in the lung. This case report examines the clinical manifestations, treatment, and mechanism of lung injury induced by PEG-rhG-CSF-mobilized PBSCs.

Psychological and physical side effects during G-CSF mobilization in related donors of allo-HCT.

The psychological side effects of granulocyte colony-stimulating factor mobilization in related donors of allogeneic hematopoietic cell transplantation (allo-HCT) and impacts of psychological/physical side effects on harvest outcomes remain largely unknown. We prospectively analyzed 349 consecutive related peripheral blood stem cell (PBSC) donors for allo-HCT at the First Affiliated Hospital, Zhejiang University, School of Medicine from March 2021 to August 2023. Higher baseline peripheral blood white blood cell counts (p = 0.046), monocyte counts (p < 0.001), platelet counts (p = 0.001), and hemoglobin (p < 0.001) had a positive correlation to CD34+ cell counts in the first leukapheresis, while female donors (male vs. female, p < 0.001) and older age (> 40 vs. < = 40, p = 0.003) were negatively related to CD34+ cell counts. Bone pain was the most observed physical side effect and was more frequent in female donors (p = 0.032). The incidence of fatigue was higher in female donors and older donors (female vs. male, p = 0.016; > 40 vs. < = 40, p = 0.015). Donor depression (pre vs. during mobilization, p < 0.001), anxiety (pre vs. during mobilization, p = 0.043) and insomnia (pre vs. during mobilization, p = 0.011) scores increased during the mobilization period. Donors with higher depression, anxiety and stress scores at admission were more likely to experience nausea. At 1 month after the last leukapheresis, the counts of white blood cell, neutrophil, monocyte and hemoglobin were significant lower than baseline counts, while the platelet counts recovered to baseline. The mobilization and harvest process can increase the depression, anxiety and insomnia scores. Poor psychological status of the donor can aggravate the occurrence of physical side effects.

Incidence of cardiovascular disease in healthy Swedish peripheral blood stem cell donors - a nationwide study.

Granulocyte colony-stimulating factor (G-CSF) is used in a majority of healthy donors to obtain peripheral blood stem cells for allogeneic stem cell transplantation. Since high levels of G-CSF activates endothelial cells and can induce a pro-coagulatory state, and fuelled by case reports of cardiovascular events in donors, some concerns have been raised about a potential for an increased risk of cardiovascular events for the donors after donation. We studied the incidence of cardiovascular disease following stem cell donation in a Swedish national register based cohort of 1098 peripheral blood stem cell donors between 1998 and 2016. The primary objective was to evaluate if the incidence of cardiovascular disease was increased for donors treated with G-CSF. The incidence of any new cardiovascular disease was 6.0 cases per 1000 person years, with a median follow up of 9.8 years. The incidence did not exceed that of age- sex- and residency-matched population controls (hazard ratio 0.90, 95% confidence interval (CI) 0.76-1.07, p-value 0.23), bone marrow donors, or non-donating siblings. Long-term cardiovascular disease incidence was not increased in this national register based study of peripheral blood stem cell donors treated with G-CSF.

[Efficacy and Safety of Etoposide Combined with Cyclophosphamide for Autologous Peripheral Blood Stem Cell Mobilization in Patients with Multiple Myeloma].

OBJECTIVE: To evaluate the efficacy and safety of etoposide combined with cyclophosphamide (EC) regimen for mobilization of autologous peripheral blood stem cells (APBSCs) in patients with multiple myeloma (MM). METHODS: The clinical data of 48 MM patients who received APBSC transplantation (APBSCT) in Department of Hematology of the First Affiliated Hospital of Nanchang University from January 2015 to October 2021 were retrospectively analyzed. The mobilization success rate and mobilization optimal rate of EC regimen were counted, and its effect on transplant efficacy, adverse reactions, hematopoietic reconstitution after transplantation, and survival time of MM patients were analyzed. RESULTS: APBSCs were collected on day 14 (10-19) after EC administration. The median of collected CD34+ cells was 6.82 (1.27-22.57)×106/kg, and the median number of apheresis session was 2 (1-4). The mobilization success rate (collecting CD34+ cells≥2×106 cells/kg after completion of apheresis) was 98% (47/48), and mobilization optimal rate (collecting CD34+ cells≥5×106 cells/kg after completion of apheresis) was 71% (34/48). The depth of remission were improved after APBSCT, and the complete remission (CR) rate increased from 45.8% before transplantation to 87.5% after transplantation (P <0.01). There was no transplant-related death, no blood transfusion during mobilization, and no mucositis occurred in the patients. The most common complication was neutropenia, with an incidence of 75.0% (36/48). After transplantation, all the patients successfully achieved hematopoietic reconstitution. The median time to neutrophil engraftment was 10 (9-26) days, and median time to platelet engraftment was 10 (8-33) days. By the end of follow-up, both the median progression-free survival (PFS) and overall survival (OS) time were not reached. The 5-year estimated PFS rate and OS rate was 53.8% and 82.4%, respectively. CONCLUSION: The EC regimen for mobilization of APBSC has a high acquisition success rate and controllable adverse reactions, which can be an effective and safe mobilization regimen in MM patients.

A phase III randomized crossover trial of plerixafor versus G-CSF for treatment of WHIM syndrome.

BACKGROUNDWarts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a primary immunodeficiency disorder caused by heterozygous gain-of-function CXCR4 mutations. Myelokathexis is a kind of neutropenia caused by neutrophil retention in bone marrow and in WHIM syndrome is associated with lymphopenia and monocytopenia. The CXCR4 antagonist plerixafor mobilizes leukocytes to the blood; however, its safety and efficacy in WHIM syndrome are undefined.METHODSIn this investigator-initiated, single-center, quadruple-masked phase III crossover trial, we compared the total infection severity score (TISS) as the primary endpoint in an intent-to-treat manner in 19 patients with WHIM who each received 12 months treatment with plerixafor and 12 months treatment with granulocyte CSF (G-CSF, the standard of care for severe congenital neutropenia). The treatment order was randomized for each patient.RESULTSPlerixafor was nonsuperior to G-CSF for TISS (P = 0.54). In exploratory endpoints, plerixafor was noninferior to G-CSF for maintaining neutrophil counts of more than 500 cells/µL (P = 0.023) and was superior to G-CSF for maintaining lymphocyte counts above 1,000 cells/µL (P < 0.0001). Complete regression of a subset of large wart areas occurred on plerixafor in 5 of 7 patients with major wart burdens at baseline. Transient rash occurred on plerixafor, and bone pain was more common on G-CSF. There were no significant differences in drug preference or quality of life or the incidence of drug failure or serious adverse events.CONCLUSIONPlerixafor was not superior to G-CSF in patients with WHIM for TISS, the primary endpoint. Together with wart regression and hematologic improvement, the infection severity results support continued study of plerixafor as a potential treatment for WHIM syndrome.TRIAL REGISTRATIONClinicaltrials.gov NCT02231879.FUNDINGThis study was funded by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases.

Severe CD8+ T Lymphopenia in WHIM Syndrome Caused by Selective Sequestration in Primary Immune Organs.

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is an ultra-rare combined primary immunodeficiency disease caused by heterozygous gain-of-function mutations in the chemokine receptor CXCR4. WHIM patients typically present with recurrent acute infections associated with myelokathexis (severe neutropenia due to bone marrow retention of mature neutrophils). Severe lymphopenia is also common, but the only associated chronic opportunistic pathogen is human papillomavirus and mechanisms are not clearly defined. In this study, we show that WHIM mutations cause more severe CD8 than CD4 lymphopenia in WHIM patients and WHIM model mice. Mechanistic studies in mice revealed selective and WHIM allele dose-dependent accumulation of mature CD8 single-positive cells in thymus in a cell-intrinsic manner due to prolonged intrathymic residence, associated with increased CD8 single-positive thymocyte chemotactic responses in vitro toward the CXCR4 ligand CXCL12. In addition, mature WHIM CD8+ T cells preferentially home to and are retained in the bone marrow in mice in a cell-intrinsic manner. Administration of the specific CXCR4 antagonist AMD3100 (plerixafor) in mice rapidly and transiently corrected T cell lymphopenia and the CD4/CD8 ratio. After lymphocytic choriomeningitis virus infection, we found no difference in memory CD8+ T cell differentiation or viral load between wild-type and WHIM model mice. Thus, lymphopenia in WHIM syndrome may involve severe CXCR4-dependent CD8+ T cell deficiency resulting in part from sequestration in the primary lymphoid organs, thymus, and bone marrow.

Splenic rupture following lenograstim in post-autologous stem cell transplantation treated with emergency open splenectomy: a case report and literature review.

Granulocyte-colony stimulating factors (G-CSFs) are the cornerstone of peripheral blood stem cell mobilization and apheresis. However, splenic rupture following G-CSF treatment represents a serious and potentially fatal adverse event. Here, we report the case of a patient in their late 50s with severe pancytopenia post-autologous stem cell transplantation reinfusion suffering from splenic rupture after treatment with lenograstim. We also reviewed the literature describing cases of splenic rupture during G-CSF administration.

[Efficacy and safety of autologous hematopoietic stem cell transplantation in elderly multiple myeloma patients: a single center retrospective study].

Objective: To evaluate the efficacy and safety of autologous hematopoietic stem cell transplantation (auto-HSCT) in elderly patients (≥65 years old) with multiple myeloma (MM) . Methods: From June 1, 2006 to July 31, 2020, 22 MM patients (≥65 years old) who were diagnosed in the First Affiliated Hospital, Sun Yat-sen University and received novel drug induction followed by auto-HSCT were analyzed retrospectively. These patients were evaluated for important organ functions before transplantation, and the International Myeloma Working Group frail score was used in 2016 to screen out transplant-eligible patients. Results: The median (interquartile range, IQR) age at the time of transplantation of the 22 patients was 66.75 (IQR 4.50) years. A total of 20 patients received stem cell mobilization. The median number of mononuclear cells collected was 4.53×10(8)/kg, that of CD34(+) cells was 3.37×10(6)/kg, and the median number of apheresis procedures performed was 2. After stem cell transfusion, the median time of neutrophil implantation was 11 days, that of platelet implantation was 13 days, and the treatment-related mortality was 0 at 100 days after transplantation. The median follow-up was 48.7 months. The median time to progression time was not reached, and the median overall survival time was 111.8 months. Conclusion: Auto-HSCT is a safe and effective treatment for selected elderly patients of 65 years or older with MM.

Diffuse alveolar hemorrhage in a healthy stem cell donor following administration of granulocyte colony - stimulating factor.

BACKGROUND: Granulocyte colony - stimulating factor (G-CSF) is frequently used in healthy adults prior to stem cell donation in order to mobilize stem cells to peripheral blood. Adverse events of G-CSF occur in about 30% and mainly include bone pain, fatigue, and headache. Pulmonary adverse events are rare. CASE PRESENTATION: Here, we describe a case of a healthy donor who developed diffuse alveolar hemorrhage after G-CSF administration. We suggest the underlying mechanism of this injury. CONCLUSION: Diffuse alveolar hemorrhage can occur following G-CSF administration. Treating physicians should be aware of this infrequent but often life-threatening pulmonary side effect of G-CSF.

Safety of outpatient stem cell mobilization with low- or intermediate-dose cyclophosphamide in newly diagnosed multiple myeloma patients.

OBJECTIVES: Autologous stem cell transplantation is the gold standard for eligible newly diagnosed multiple myeloma patients. Patients are usually hospitalized for administration of mobilization chemotherapy. We aimed to assess safety and efficacy of mobilization therapy with low-dose (2 g/m2 ) and intermediate-dose (3-4 g/m2 ) cyclophosphamide administered as outpatient. METHODS: A total of 176 consecutive newly diagnosed transplant-eligible myeloma patients receiving outpatient mobilization were retrospectively evaluated. Induction therapy was mainly performed with new drugs (91%). RESULTS: Chemotherapy was very well tolerated with 16.6% of patients having all-grade adverse events (AEs) and only 1.2% having severe AEs. The most frequently reported AEs were nausea and vomiting grade 1-2 (6.8%). Only 5.7% of patients required hospitalization for AEs. Stem cell collection was successful in 93.1% of patients, with a median CD34+ harvest of 8.7 × 106 /kg. Target for 2 autologous stem cell transplantation (at least 6 CD34+  × 106 /kg) was reached by 76.3% of patients. Administration of plerixafor on demand was necessary in 12.1% of patients. CONCLUSIONS: Outpatient mobilization with low- and intermediate-dose cyclophosphamide appears an efficient and safe procedure, with minimal and manageable AEs and low rate of hospitalization.

Granulocyte Colony-Stimulating Factor Effectively Mobilizes TCR γδ and NK Cells Providing an Allograft Potentially Enhanced for the Graft-Versus-Leukemia Effect for Allogeneic Stem Cell Transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potential cure for patients with hematological malignancies but substantial risks of recurrence of the malignant disease remain. TCR γδ and NK cells are perceived as potent innate effector cells in HSCT and have been associated with post-transplant protection from relapse in clinical studies. Immunocompetent cells from the donor are crucial for patient outcomes and peripheral blood stem cells (PBSC) are being increasingly applied as graft source. G-CSF is the preferential mobilizing agent in healthy donors for PBSC grafts, yet effects of G-CSF on TCR γδ and NK cells are scarcely uncovered and could influence the graft composition and potency of these cells. Therefore, we analyzed T and NK cell subsets and activation markers in peripheral blood samples of 49 donors before and after G-CSF mobilization and-for a subset of donors-also in the corresponding graft samples using multicolor flowcytometry with staining for CD3, CD4, CD8, TCRαß, TCRγδ, Vδ1, Vδ2, HLA-DR, CD45RA, CD197, CD45RO, HLA-DR, CD16, CD56, and CD314. We found that TCR γδ cells were mobilized and harvested with an efficiency corresponding that of TCR αß cells. For TCR γδ as well as for TCR αß cells, G-CSF preferentially mobilized naïve and terminally differentiated effector (TEMRA) cells over memory cells. In the TCR γδ cell compartment, G-CSF preferentially mobilized cells of the nonVδ2 types and increased the fraction of HLA-DR positive TCR γδ cells. For NK cells, mobilization by G-CSF was increased compared to that of T cells, yet NK cells appeared to be less efficiently harvested than T cells. In the NK cell compartment, G-CSF-stimulation preserved the proportion of CD56dim NK effector cells which have been associated with relapse protection. The expression of the activating receptor NKG2D implied in anti-leukemic responses, was significantly increased in both CD56dim and CD56bright NK cells after G-CSF stimulation. These results indicate differentiated mobilization and altering properties of G-CSF which could improve the effects of donor TCR γδ and NK cells in the processes of graft-versus-leukemia for relapse prevention after HSCT.

Stem cell mobilization in multiple myeloma patients relapsing after previous autologous hematopoietic stem cell transplantation: A multicenter report by the Polish Myeloma Study Group.

BACKGROUND: Salvage autologous hematopoietic stem cell transplantation (autoHSCT) may be used to treat relapse of multiple myeloma occurring after previous autoHSCT. When insufficient number of hematopoietic stem cells was stored from the initial harvest, remobilization of stem cells is necessary. PURPOSE: The analysis of stem cell remobilization after previous autoHSCT. PATIENTS AND METHODS: Fifty-eight patients, 60% males, median 59 years, were included. Median time interval between autoHSCT and remobilization was 42 months. The first remobilization was performed mostly after chemotherapy: cyclophosphamide (33%), cytarabine (43%), and etoposide (19%). RESULTS: The first remobilization was successful in 67% patients. About 19% patients required plerixafor rescue, among whom it allowed for successful harvesting in 14%. Use of cyclophosphamide, cytarabine, and etoposide allowed for successful remobilization in 53%, 84%, and 55% patients, respectively. Patients treated with cytarabine had the highest yield of CD34+ cells (median 7.5 × 106 /kg vs 5.8 and 2.4 for etoposide and cyclophosphamide, P = .001). Higher percentage of patients was able to collect ≥2 × 106 CD34+ cells/kg during one leukapheresis after cytarabine (76% vs 21% for cyclophosphamide vs 36% for etoposide, P = .001). Cytarabine use was associated with lower risk of remobilization failure OR = 0.217, P = .02. Toxicity comprised mostly hematological toxicity (thrombocytopenia and neutropenia). One patient succumbed to septic shock. CONCLUSION: Remobilization after previous autoHSCT is feasible only in a proportion of patients. Cytarabine is associated with the highest rate of successful mobilization and the highest yield of mobilized CD34+ cells. The toxicity requires careful surveillance of these patients.

Vascular access for optimal hematopoietic stem cell collection.

BACKGROUND: Autologous and allogeneic hematopoietic stem cell transplantation of cytokine-mobilized peripheral blood stem cells (PBSCs) is increasingly used to treat patients with hematologic disorders. Different types of vascular access have been exploited for the apheresis procedure, including peripheral veins (PV) and central venous catheter (CVC). In some cases, PV access is unavailable. There are few published data on the efficiency and quality of harvesting with different types of vascular access. This study brings out complications and morbidity of this procedure linked to these different access. METHODS: We performed a comparative, retrospective, single-center study of hematopoietic stem cell collection using these two types of vascular access. We compared the efficiency and complication rate for 617 adults apheresis sessions in 401 patients and healthy donors, for PBSC collection via PV or CVC between 2010 and 2016. The quality of the HSC product was evaluated in terms of the total CD34 + count and neutrophil contamination. RESULTS: The PV and CVC groups did not differ significantly in terms of the quality of the apheresis product, mean ± SD CD34 + cells collected in PV group was 383.1 ± 402.7 × 10e6 and 298.8 ± 372.7 × 10e6 and the level of neutrophil contamination was 21.0 ± 17.8% in the PV group and 20.6 ± 18.4% in the CVC group. The complication rate did not differ between the two groups. CONCLUSION: The type of vascular access for apheresis hematopoietic stem cell harvesting must be determined by trained staff. Successful harvesting can be performed via PV then CVC is not needed or not available.

Transplant in Aplastic Anemia Using Combined Granulocyte Colony-Stimulating Factor Primed Blood and Bone Marrow Stem Cells: A Retrospective Analysis.

INTRODUCTION: Aplastic anemia (AA) is characterized by diminished hematopoietic precursors in the bone marrow, most often due to injury to the pluripotent stem cell. In Pakistan, AA is not uncommon, and allogeneic hematopoietic stem cell transplant remains the only curative option for these patients. OBJECTIVE: The objective of this study was to determine the transplant outcome of combined granulocyte colony-stimulating factor (G-CSF) primed blood and bone marrow grafts in adult and pediatric patients with AA. METHODS: We retrospectively collected the data of all transplant procedures performed from 2004 to 2019 at Aga Khan University in Karachi, Pakistan. Variables analyzed included age, sex, type of stem cells used, conditioning regimens, and overall survival for patients undergoing transplant in AA. RESULTS: A total of 351 transplants were performed during the study period. Out of these, 239 were allogeneic transplants, whereas 112 were autologous procedures. We performed 70 transplants for AA during the study period, of which 52 were male patients and 18 were female patients. The median age ± standard deviation (SD) was 17.5 ± 9.4 years (range, 2-43 years). Cyclophosphamide/antithymocyte globulin (ATG) was used as a conditioning regimen in 65 patients, while ATG/cyclophosphamide/fludarabine was used in 5 patients. In 60 patients, a combination of G-CSF primed blood and bone marrow stem cells were used. The mean CD34 count was 5.2 × 106/kg. Graft-vs-host disease (GVHD) prophylaxis was done with cyclosporine and methotrexate. All patients received standard infection prophylaxis. Engraftment was achieved in 86% of patients. The median day of myeloid engraftment was 15 (range, 10-22 days). Chronic GVHD was present in 3 patients while 4 had acute GVHD. The overall survival was 71.2% (median duration of 80 months). The main cause of mortality was gram-negative sepsis. CONCLUSION: A combination of blood and bone marrow stem cells results in early engraftment with decreased frequency of GVHD in AA. The overall survival was comparable to international literature.

Severe, Reversible Acute Lung Injury During Autologous Hematopoietic Stem Cell Mobilization After Filgrastim in a Child With Neuroblastoma: A Case Report.

Peripheral blood hematopoietic stem cell mobilization is widely performed in a variety of clinical facilities and is believed to be a safe outpatient procedure. In this report, we describe a child with neuroblastoma who developed an extremely severe acute lung injury after granulocyte colony-stimulating factor was used for peripheral hematopoietic stem cell mobilization. A 3-year-old boy with a medical history of patent foramen ovale and secundum atrial septal defect was diagnosed with an MYCN-amplified neuroblastoma and treated with chemotherapy. During stem cell mobilization with filgrastim, the boy was in very good clinical condition, with a peripheral white blood cell (WBC) count of 57.17 K/µL, but he suddenly deteriorated, and nausea, seizures, and nystagmus were observed. The patient developed dyspnea with hemoptysis, and lung computed tomography showed bilateral asymmetrical pulmonary opacification demonstrating an anteroposterior density gradient. Because of rapidly progressing circulatory and respiratory failure, the child was hospitalized in the intensive care unit. Corticosteroid therapy, broad-spectrum antibiotic therapy, and cardiovascular support with mechanical ventilation were immediately instituted, and the child recovered without sequelae. The presented case emphasizes that life-threatening complications can occur during granulocyte colony-stimulating factor administration, and patient surveillance is warranted, especially if high leukocyte counts are observed or the patient exhibits cardiopulmonary signs.

Stem cell mobilization with plerixafor and healing of diabetic ischemic wounds: A phase IIa, randomized, double-blind, placebo-controlled trial.

Bone marrow-derived cells contribute to tissue repair, but traffic of hematopoietic stem/progenitor cells (HSPCs) is impaired in diabetes. We therefore tested whether HSPC mobilization with the CXCR4 antagonist plerixafor improved healing of ischemic diabetic wounds. This was a pilot, phase IIa, double-blind, randomized, placebo-controlled trial (NCT02790957). Patients with diabetes with ischemic wounds were randomized to receive a single subcutaneous injection of plerixafor or saline on top of standard medical and surgical therapy. The primary endpoint was complete healing at 6 months. Secondary endpoints were wound size, transcutaneous oxygen tension (TcO2 ), ankle-brachial index (ABI), amputations, and HSPC mobilization. Twenty-six patients were enrolled: 13 received plerixafor and 13 received placebo. Patients were 84.6% males, with a mean age of 69 years. HSPC mobilization was successful in all patients who received plerixafor. The trial was terminated after a preplanned interim analysis of 50% of the target population showed a significantly lower healing rate in the plerixafor vs the placebo group. In the final analysis data set, the rate of complete healing was 38.5% in the plerixafor group vs 69.2% in the placebo group (chi-square P = .115). Wound size tended to be larger in the plerixafor group for the entire duration of observation. No significant difference was noted for the change in TcO2 and ABI or in amputation rates. No other safety concern emerged. In conclusion, successful HSPC mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Contrary to what was expected, outside the context of hematological disorders, mobilization of diabetic HSPCs might exert adverse effects on wound healing.

Extracellular Adenosine Triphosphate (eATP) and Its Metabolite, Extracellular Adenosine (eAdo), as Opposing "Yin-Yang" Regulators of Nlrp3 Inflammasome in the Trafficking of Hematopoietic Stem/Progenitor Cells.

Nlrp3 inflammasome plays a pleiotropic role in hematopoietic cells. On the one hand, physiological activation of this intracellular protein complex is crucial to maintaining normal hematopoiesis and the trafficking of hematopoietic stem progenitor cells (HSPCs). On the other hand, its hyperactivation may lead to cell death by pyroptosis, and prolonged activity is associated with sterile inflammation of the BM and, as a consequence, with the HSPCs aging and origination of myelodysplasia and leukemia. Thus, we need to understand better this protein complex's actions to define the boundaries of its safety window and study the transition from being beneficial to being detrimental. As demonstrated, the Nlrp3 inflammasome is expressed and active both in HSPCs and in the non-hematopoietic cells that are constituents of the bone marrow (BM) microenvironment. Importantly, the Nlrp3 inflammasome responds to mediators of purinergic signaling, and while extracellular adenosine triphosphate (eATP) activates this protein complex, its metabolite extracellular adenosine (eAdo) has the opposite effect. In this review, we will discuss and focus on the physiological consequences of the balance between eATP and eAdo in regulating the trafficking of HSPCs in an Nlrp3 inflammasome-dependent manner, as seen during pharmacological mobilization from BM into peripheral blood (PB) and in the reverse mechanism of homing from PB to BM and engraftment. We propose that both mediators of purinergic signaling and the Nlrp3 inflammasome itself may become important therapeutic targets in optimizing the trafficking of HSPCs in clinical settings.

GENESIS: Phase III trial evaluating BL-8040 + G-CSF to mobilize hematopoietic cells for autologous transplant in myeloma.

Effective hematopoietic cell transplantation relies upon collecting adequate numbers of CD34+ hematopoietic stem cells, typically from peripheral blood. A minimum of ≥2 × 106 CD34+ cells/kg are necessary, while transplants of ≥5-6 × 106 CD34+ cells/kg are associated with improved hematopoietic recovery. Granulocyte colony stimulating factor (G-CSF) remains the gold standard for hematopoietic stem cell mobilization. However, in randomized trials for autologous-hematopoietic cell transplantation in multiple myeloma, approximately 45% of patients remain unable to optimally mobilize with G-CSF alone despite multiple injections and apheresis days. Therefore, reducing mobilization failures remains an unmet need. The study objective is to evaluate the superiority of one dose of BL-8040 plus G-CSF over placebo plus G-CSF to mobilize ≥6.0 × 106 CD34+ cells/kg in up to two apheresis days. ClinicalTrials.gov: NCT03246529.