Increase In Peripheral Blood CD34 Research Articles

A Phase I Safety and Feasibility Study to Evaluate Motixafortide (CXCR4/SDF-1 Inhibition) and Natalizumab (VLA-4/VCAM-1 Inhibition) As a Novel Regimen to Mobilize CD34+ Hematopoietic Stem Cells for Gene Therapy in Sickle Cell Disease

Background: Sickle cell disease (SCD) is one of the most common genetic diseases globally. Clinical manifestations of SCD commonly include anemia, pain, vaso-occlusive events and cumulative end organ damage leading to significant morbidity and mortality. Historically, allogeneic hematopoietic cell transplantation (HCT) represented the only curative therapy for SCD, but is associated with significant HCT-related morbidity and mortality which limit its use (PMID: 8663884, PMID: 20007560). Autologous hematopoietic stem cell (HSC) -based gene therapies now offer curative potential with decreased toxicity (PMID: 28249145). However, effective HSC-based gene therapy depends on collection of sufficient HSCs (ideally >10x106 CD34+ cells/kg), typically from peripheral blood (PB) (PMID: 33956057). G-CSF and CXCR4 inhibition (CXCR4i) with plerixafor are the most widely used mobilization strategies (PMID: 19363221, PMID: 19720922). However, G-CSF is associated with risk of fatal vaso-occlusive events in SCD (PMID: 9734950, PMID: 11368061, PMID: 19513902). Meanwhile, short-acting CXCR4i with plerixafor alone does not reliably yield optimal HSC numbers for gene therapy applications (PMID: 30282642, PMID: 29419425, PMID: 29472357). Therefore, developing novel HSC mobilization regimens to rapidly and reliably mobilize optimal CD34+ HSCs for gene therapy in SCD represents an unmet need. Motixafortide (M) is a high-affinity, long-acting CXCR4 inhibitor. The recent Phase III, randomized, controlled GENESIS Trial demonstrated combination M+G-CSF resulted in 88.8% of patients collecting ≥6x106 CD34+ cells/kg (median 10.8x106) within 1 leukapheresis (LP) for HCT. This compares favorably to historical data with plerixafor+G-CSF where 54.2% collected to goal in 1 LP. Motixafortide also mobilized more immunophenotypically primitive HSCs and multi-potent progenitors compared to plerixafor. Meanwhile, transcriptional profiling by single-cell RNA sequencing revealed HSCs mobilized with M have gene expression profiles associated with enhanced regeneration and self-renewal, compared to G-CSF or plerixafor (DOI: 10.1182/blood-2021-144296). Motixafortide alone also mobilized an average of 11.6×106 CD34+ cells/kg in healthy volunteers, while mobilizing 91.6% of allogeneic HSC donors to goal in ≤2 LPs (median 6.07x106) (DOI: 10.1182/blood-2018-99-109701, PMID: 28835380). Natalizumab (N) is a monoclonal antibody to the a4 integrin subunit of a4b1 (VLA-4) capable of VLA4 inhibition (VLA4i). In mice and primates, N led to an ~8-fold increase in PB CD34+ HSCs in 24 hrs (PMID: 7692447). In humans, a single N infusion resulted in a 5- to 6-fold increase PB CD34+ HSCs. Meanwhile, the average PB CD34+ HSC levels after a single dose were similar to levels with repeated doses, indicating rapid mobilization of maximal PB HSCs by 24 hrs after N infusion (PMID: 18195093). Combination CXCR4i and VLA-4i has been well-tolerated and resulted in synergistic mobilization of HSCs in preclinical studies (PMID: 21886173). Therefore, we hypothesize that combination CXCR4i and VLA-4i with M+N represents a safe and effective strategy for robust, rapid and synergistic mobilization of HSCs to PB in patients with SCD. Study Design and Methods: This is a single center, single-arm, dose de-escalation, Phase 1 safety and feasibility study. Key eligibility criteria include patients with SCD (SS or Sβ0) age 18-35 years receiving automated RBC exchanges. Patients with prior HCT or gene therapy will be excluded. We estimate 5 patients in this pilot feasibility study will provide sufficient safety and preliminary efficacy data to guide further development of this novel mobilization strategy. All patients will have baseline labs prior to M (1.25mg/kg, subcutaneous), N (300mg, IV) and M+N dosing. Each patient will then undergo mobilization and LP (1 blood volume), per protocol (see Figure 1). The primary outcome will be to assess the safety and tolerability of M, N and M+N in each SCD patient, defined by dose-limiting toxicities and maximum tolerated dose. Key secondary outcomes include: kinetics of CD34+ HSC mobilization to PB (CD34+ cells/uL), number of CD34+ HSCs collected via LP (CD34+ cells/kg/L), incidence of AEs, pharmacokinetics and the recommended phase 2 dose. Correlative studies include immunophenotypic and single cell transcriptional profiling of CD34+ HSCs from LP product mobilized with M, N and M+N. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Пул гемопоэтических стволовых клеток в периферической крови хронически облученных лиц в отдаленном периоде

Changes in the peripheral blood cellular composition were observed in the long term period in the residents of the Techa riverside villages chronically exposed to radiation, which may be the consequence of structural and functional disorders in the pool of hematopoietic stem cells (HSC) and progenitor cells. Therefore, the study was aimed to quantify peripheral blood CD34+ cell pool in individuals chronically exposed to radiation over a long-term period. Sixty years after the onset of exposure, a total of 153 individuals were examined, who were divided into four groups: individuals exposed in utero and postnatally (the average postnatal absorbed dose was 570 mGy); individuals exposed only postnatally (the average postnatal absorbed dose was 790 mGy), and two comparison groups, in which the average postnatal absorbed dose to red bone marrow did not exceed 70 mGy. Absolute and relative peripheral blood CD34+ cell counts in chronically exposed individuals were assessed by flow cytometry. No changes in CD34+ cell counts compared to comparison group were revealed in the group of individuals exposed in utero and postnatally; no age-related changes were registered as well. However, a significant decline in absolute HSC and progenitor cell counts with increased absorbed dose to red bone marrow was observed. In the group of individuals exposed only postnatally, there was a significant increase in peripheral blood CD34+ cell counts compared to comparison group (p = 0.004 for absolute cell count; p = 0.009 for relative cell count), dose-dependent increase in peripheral blood HSC and precursor cell counts (p = 0.02 for absolute cell count; p = 0.03 for relative cell count), along with age-related decline in these cells’ counts (р = 0.02 for absolute cell count; p = 0.04 for relative cell count).

A multicenter report on the safety and efficacy of plerixafor based stem cell mobilization in children with malignant disorders.

Pleraxifor for peripheral blood stem cell (PBSC) mobilization in children with malignancies is often given following failure of standard mobilization (SM) rather than as a primary mobilizing agent. In this retrospective multicenter study, we report the safety of plerixafor-based PBSC mobilization in children with malignancies and compare outcomes between patients who received plerixafor upfront with SM (Group A) with those who received plerixafor following failure of SM (Group B). In the latter pleraxifor was given either following a low peripheral blood (PB) CD34 (<20 cells/cu.mm) (Group B1) or as a second collection process due to an unsuccessful yield (CD34 + < 2 × 106 /kg) (Group B2) following failed SM and first apheresis attempts. The study cohort (n = 47) with a median age of 8 (range 0.6-21) year, comprised 19 (40%) Group A and 28 (60%) Group B patients (B1 = 12 and B2 = 16). Pleraxifor mobilization was successful in 87.2% of patients, similar between Groups A and B (84.2% vs 89.2%) and resulted in a median 4-fold increase in PB CD34. Median number of apheresis attempts was 2 in Groups A and B1 but 4 in Group B2. In Group B2, median total CD34+ yield post-plerixafor was 9-fold higher than after SM (P = .0013). Mild to moderate transient adverse events affected 8.5% of patients. Among patients who proceeded to autologous transplant (n = 39), all but one engrafted. Plerixafor-based PBSC collection was safe and effective in our cohort and supports consideration as a primary mobilizing agent in children with malignancies.

EMA Recommendation for the Pediatric Indications of Plerixafor (Mozobil) to Enhance Mobilization of Hematopoietic Stem Cells for Collection and Subsequent Autologous Transplantation in Children with Lymphoma or Malignant Solid Tumors.

On March 28, 2019, the Committee for Medicinal Products for Human Use adopted a positive opinion recommending the marketing authorization for the medicinal product plerixafor. The marketing authorization holder for this medicinal product is Genzyme Europe B.Th. The adoption was for an extension of the existing adult indication in combination with granulocyte colony-stimulating factor (G-CSF) to pediatric patients (aged 1 year to <18 years) to enhance mobilization of hematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation in children with lymphoma or solid malignant tumors. This treatment is indicated either preemptively, when circulating stem cell count on the predicted day of collection after adequate mobilization with G-CSF (with or without chemotherapy) is expected to be insufficient with regard to desired hematopoietic stem cells yield, or in children who previously failed to collect sufficient hematopoietic stem cells. The efficacy and safety of plerixafor were evaluated in an open label, multicenter, phase I/II, dose-ranging, and randomized controlled study (DFI12860) in pediatric patients with solid tumors, including neuroblastoma, sarcoma, Ewing sarcoma, or lymphoma, who were eligible for autologous hematopoietic stem cell transplantation. Forty-five patients (aged 1 year to <18 years) were randomized, 2:1, using 0.24 mg/kg of plerixafor plus standard mobilization (G-CSF with or without chemotherapy) versus control (standard mobilization alone). The primary analysis showed that 80% of patients in the plerixafor arm experienced at least a doubling of the peripheral blood (PB) CD34+ count, observed from the morning of the day preceding the first planned apheresis to the morning prior to apheresis, versus 28.6% of patients in the control arm (p = .0019). The median increase in PB CD34+ cell counts from baseline to the day of apheresis was 3.2-fold in the plerixafor arm versus by 1.4-fold in the control arm. The observed safety profile in the pediatric population was consistent with that in adults, with adverse events mainly related to injection site reactions, hypokalemia, and increased blood bicarbonate. Importantly, plerixafor exposure did not seem to negatively affect transplant efficiency. This article summarizes the scientific review of the application leading to regulatory approval in the European Union. IMPLICATIONS FOR PRACTICE: This review of the marketing authorization of plerixafor will raise awareness of pediatric indication granted for this medicinal product.

Therapeutic targeting and rapid mobilization of endosteal HSC using a small molecule integrin antagonist.

The inherent disadvantages of using granulocyte colony-stimulating factor (G-CSF) for hematopoietic stem cell (HSC) mobilization have driven efforts to identify alternate strategies based on single doses of small molecules. Here, we show targeting α9β1/α4β1 integrins with a single dose of a small molecule antagonist (BOP (N-(benzenesulfonyl)-L-prolyl-L-O-(1-pyrrolidinylcarbonyl)tyrosine)) rapidly mobilizes long-term multi-lineage reconstituting HSC. Synergistic engraftment augmentation is observed when BOP is co-administered with AMD3100. Impressively, HSC in equal volumes of peripheral blood (PB) mobilized with this combination effectively out-competes PB mobilized with G-CSF. The enhanced mobilization observed using BOP and AMD3100 is recapitulated in a humanized NODSCIDIL2Rγ−/− model, demonstrated by a significant increase in PB CD34+ cells. Using a related fluorescent analogue of BOP (R-BC154), we show that this class of antagonists preferentially bind human and mouse HSC and progenitors via endogenously primed/activated α9β1/α4β1 within the endosteal niche. These results support using dual α9β1/α4β1 inhibitors as effective, rapid and transient mobilization agents with promising clinical applications.

Plerixafor and G-CSF for autologous stem cell mobilization in patients with NHL, Hodgkin’s lymphoma and multiple myeloma: results from the expanded access program

Before US regulatory approval, an expanded access program provided plerixafor to patients with non-Hodgkin's lymphoma (NHL), Hodgkin's lymphoma (HD) or multiple myeloma (MM) who had not previously failed mobilization and were otherwise candidates for auto-SCT. Patients received granulocyte-CSF (G-CSF) 10 mcg/kg daily and plerixafor 0.24 mg/kg starting on day 4 with apheresis on day 5; all repeated daily until collection was complete. Overall, 104 patients received 1 dose of plerixafor. The addition of plerixafor to G-CSF resulted in a median threefold increase in peripheral blood CD34+ cell count between days 4 and 5. Among 43 NHL patients, 74% met the target of 5 × 10(6) CD34+ cells/kg (median, 1 day apheresis, range 1-5 days); among 7 HD patients, 57% met the target of 5 × 10(6) CD34+ cells/kg (median, 2 days apheresis, range 1-3); and among 54 MM patients, 89% met the target of 6 × 10(6) CD34+ cells/kg (median, 1 day apheresis, range 1-4). Overall, 93% of patients had 2 × 10(6) CD34+ cells/kg collected within 1-3 days. Plerixafor-related toxicities were minimal. Engraftment kinetics, graft durability and transplant outcomes demonstrated no unexpected outcomes. Efficacy and safety results were similar to results in phase II and III clinical trials.

Plerixafor Salvage Is Safe and Effective in Hard-to-Mobilize Patients Undergoing Chemotherapy and Filgrastim-Based Peripheral Blood Progenitor Cell Mobilization

The combination of filgrastim (G-CSF) and plerixafor is currently approved for mobilizing peripheral blood progenitor cells in patients with non-Hodgkin lymphoma and multiple myeloma undergoing autologous peripheral blood hematopoietic cell transplantation. However, chemotherapy and G-CSF-based mobilization remains a widely used strategy for peripheral blood progenitor cell collection. In this paper we describe our experience from two North American transplant centers in a series of patients who received salvage plerixafor while failing chemotherapy and G-CSF mobilization. Patients received a median of two doses of plerixafor salvage upon failure to mobilize adequate number of peripheral blood progenitor cells at neutrophil recovery. The use of plerixafor was associated with a 2.4-fold increase in peripheral blood CD34+ cell count and 3.9-fold increase in total CD34+ cell yield. All patients were able to collect ≥2 × 106 CD34+ cells/kg with this approach. These results were more pronounced in patients with a higher CD34+ cell count at the time of the first plerixafor dose. Interestingly, peripheral blood white blood cell count was not shown to correlate with a response to plerixafor. Our results provide safety and efficacy data for the use of plerixafor in patients who are destined to fail chemomobilization.

Plerixafor (Mozobi ®)Plus G-CSF Is More Effective Than Placebo Plus G-CSF in Mobilizing CD34+ Hematopoietic Stem Cells in Patients with Multiple Myeloma Who Have Low (

Abstract 3230Poster Board III-167 BackgroundPre-apheresis peripheral blood (PB) CD34+ cells of < 20 cells/μl is a significant risk factor for poor hematopoietic stem cell (HSC) mobilization and collection in patients with multiple myeloma (MM) undergoing autologous HSC transplantation (auto-HSCT). PB CD34+ cells are routinely monitored to optimize the timing and success of HSC collection after mobilization with cytokines ± chemotherapy. This analysis was designed to compare the efficacy of plerixafor + G-CSF to placebo + G-CSF for mobilization in patients with MM who had pre-apheresis PB CD34+ cell counts < 20 cells/μl. We hypothesized that the addition of plerixafor to G-CSF would improve the stem cell yield in these patients with baseline CD34+ cells < 20 cells/μl. MethodsData were obtained from a prospective, randomized, double-blind, placebo-controlled, phase 3 clinical trial that compared the safety and efficacy of plerixafor (0.24 mg/kg/day SC) + G-CSF (10 μg/kg/day) to placebo + G-CSF for mobilization and auto-HSCT in patients with MM. PB CD34+ cell count was measured on Day 4, prior to first plerixafor/placebo dose, and on Day 5, 10-11 hours post study treatment. The proportion of patients achieving the minimal (≥2 × 106 CD34+ cells/kg) or optimal (≥6 × 106 CD34+ cells/kg) cell doses in 2 apheresis days, apheresis yields, and time to engraftment were compared between the plerixafor and placebo groups for PB CD34+ cell count <10 cells/μl (PB<10) and <20 cells/μl (PB<20). ResultsIn the plerixafor group (n=148), 27 (18%) and 56 (38%) patients had Day 4 PB CD34+ cells/μl <10 and <20 which was as expected identical to the 30 (19%) and 60 (39%) patients in the placebo group, respectively (n=154). Patient characteristics were similar in both groups. Plerixafor + G-CSF resulted in a statistically significant increase in the absolute PB CD34+ cells/ml on Day 5 compared to placebo + G-CSF (p<0.001; Table 1). For patients with PB <10, the median fold increase in PB CD34+ cells in the plerixafor (n = 27) vs. placebo (n = 30) groups was 9.6 vs. 2 (p<0.001). Similarly, for patients with PB <20 the median fold increase in PB CD34+ cells in the plerixafor (n = 56) vs. placebo (n = 60) groups was 6.6 vs. 2 (p<0.001).The median CD34+ cell yield after 2 aphereses was significantly higher in the plerixafor vs. placebo group: 5.44 vs.1.68 × 106 cells/kg (p<0.001; PB<10) and 7.06 vs. 3.27 × 106 cells/kg (p<0.001; PB <20). The proportion of patients achieving ≥2 × 106 CD34+ cells/kg in 2 aphereses was significantly higher in the plerixafor group compared to the placebo group: 92.6% vs. 43.3 % in patients with PB<10 (p<0.001), and 94.6% vs. 66.7% in patients with PB<20 (p<0.001). Similarly, the proportion of patients achieving ≥6 × 106 CD34+ cells/kg in 2 apheresis days was significantly higher in the plerixafor vs. placebo group: 40.7% vs. 3.3 % in patients with PB<10 (p<0.001), and 55.4% vs. 15% in patients with PB<20 (p<0.001). The median time to platelet (19-20 days) and neutrophil (11 days) engraftment was similar in both groups. ConclusionsThese data demonstrate that in patients with MM who are predicted to fail mobilization based on low PB CD34+ cell count, the addition of plerixafor to G-CSF allows for 2-day collection of the minimal and optimal cell dose in a greater proportion of patients compared to G-CSF alone. Thus, addition of plerixafor to G-CSF can decrease the risk of poor mobilization in patients with MM who have PB CD34+ cell counts < 20 or even < 10 cells/μl.Table 1Plerixafor + G-CSF n=148Placebo + G-CSF n=154P-ValueNumber of Patients with Day 4 Absolute PB CD34+ cells/μl< 102730-< 205660-Day 5 Absolute PB CD34+ cells/μl*< 1048.50 (4-314.6)11.61 (1.2- 27)<0.001< 2066.00 (4-314.6)20.20 (1.2-55.8)<0.001Fold Increase in PB CD34+ cells/μl from Day 4 to Day 5*#< 109.6 (4-70.1)2.0 (0.4-5.5)<0.001< 206.6 (2.7-70.1)2.0 (0.4-5.5)<0.001Cumulative CD34+ cells/kg x 106 after 2 apheresis days*< 105.44 (0.63-25.81)1.68 (0.11-11.37)<0.001< 207.06 (0.63-25.81)3.27 (0.11-11.37)<0.001% Patients achieving ≥2 × 106 CD34+ Cells/Kg in 2 days< 1092.643.3<0.001< 2094.666.7<0.001% Patients achieving ≥6 × 106 CD34+ Cells/Kg in 2 days< 1040.73.3<0.001< 2055.415.0<0.001Days to Platelet Engraftment*< 1020 (10-92)19 (1-95)0.370< 2020 (1-92)19 (1-95)0.153Days to Neutrophil Engraftment*< 1011 (10-22)11 (7-18)0.993< 2011 (2-22)11 (7-18)0.504*Values represent Median (Range)#Expressed as a ratio of the pre-G-CSF CD34+ cells/μL on Day 5 to pre-G-CSF CD34+ cells/μL on Day 4 DisclosuresNademanee:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Stadtmauer:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Micallef:Genzyme Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding. Stiff:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Marulkar:Genzyme Corporation: Employment, Equity Ownership. Calandra:Genzyme Corporation: Consultancy, Equity Ownership. DiPersio:Genzyme: Honoraria.

Plerixafor Plus G-CSF Is An Effective Regimen to Mobilize Hematopoietic Stem Cells in NHL Patients with Circulating Peripheral Blood CD34+ Cells/μl < 10.

Abstract 33 Background:Circulating levels of peripheral blood (PB) CD34+ cells/μl are a strong predictor of hematopoietic stem cell (HSC) yields in patients with non-Hodgkin's lymphoma (NHL) undergoing autologous HSC transplantation (auto-HSCT), and are routinely monitored to optimize the timing and success of HSC collection after cytokine ± chemotherapy mobilization. The threshold PB CD34+ cell count to initiate apheresis varies from 5-20 cells/μl, depending on the institution. This analysis compared the efficacy of plerixafor + G-CSF to placebo + G-CSF for HSC mobilization in NHL patients with pre-apheresis PB CD34+ cells/μl <10. Methods:Data were obtained from a randomized, double-blind, phase 3 clinical trial comparing the safety and efficacy of plerixafor (0.24 mg/kg/day SC) + G-CSF (10 μg/kg/day) to placebo + G-CSF for mobilization and auto-HSCT in NHL patients. PB CD34+ cell count was measured on Day 4, before the first plerixafor/placebo dose, and on Day 5, 10-11 hours post study drug treatment. The proportion of patients collecting ≥2 × 106 (minimal) or ≥5 × 106 (optimal) CD34+ cells/kg, apheresis yields, and time to engraftment were compared between the plerixafor and placebo groups for patients with PB CD34+ cells/μl <10. Results:77/150 (51%) patients and 73/148 (49%) patients in the plerixafor and placebo groups, respectively, had PB CD34+ cells/μl <10 on Day 4, prior to the first dose of study drug. Patient characteristics were similar between both groups. As shown in Table 1, addition of plerixafor to G-CSF resulted in a statistically significant increase in the absolute PB CD34+ cells/μl on Day 5 compared to G-CSF alone (p<0.001). The median fold increase in PB CD34+ cells from Day 4 to Day 5 was significantly higher in plerixafor-treated patients vs. placebo-treated patients: 6.0-fold vs. 1.6-fold (p<0.001). In these hard to mobilize patients, the median CD34+ cell yield after 2 days was significantly higher with plerixafor + G-CSF compared to placebo + G-CSF: 2.92 vs.0.94 × 106 cells/kg (p<0.001), respectively. The median CD34+ cell yield after 4 days was also significantly higher in the plerixafor vs. placebo groups: 3.96 vs.1.25 × 106 cells/kg (p<0.001). Plerixafor + G-CSF allowed a significantly greater proportion of patients with PB CD34+ cells/μl <10 to collect the minimal cell dose in 4 apheresis days: 77.9% vs. 34.2 % patients in the plerixafor and placebo group, respectively collected ≥2 × 106 CD34+ cells/kg in 4 days (p<0.001). The success rate of collecting the ≥5 × 106 CD34+ cells/kg in 4 days was 40.3% with plerixafor + G-CSF compared to only 9.6% with placebo + G-CSF (p<0.001). The proportion of patients collecting the optimal or minimal cell dose in 2 days was also significantly higher in the plerixafor vs. placebo group (p<0.001). The median time to platelet (19-21 days) and neutrophil (10-11 days) engraftment was similar in both groups. Similar, statistically significant increases in PB CD34+ cell collections were obtained when the efficacy of plerixafor + G-CSF was compared to placebo + G-CSF, in patients with a Day 4 PB CD34 cells/μl<20 (data not shown).Table 1:Mobilization efficacyPlerixafor + G-CSF n=77Placebo + G-CSF n=73P-ValueDay 5 Absolute PB CD34+ cells/μl *21.71 (0.46-126.4)5.80 (0-28)<0.001Fold Increase in PB CD34+ cells/μl *#61.6<0.001Cumulative CD34+ cells/kg x 106 after 2 apheresis days*2.92 (0.03-29.22)0.94 (0.06-9.16)<0.001Cumulative CD34+ cells/kg x 106 after 4 apheresis days*3.96 (0.03-29.22)1.25 (0.06-10.58)<0.001% Patients achieving ≥2 × 106 CD34+ Cells/Kg in 4 days77.934.2<0.001% Patients achieving ≥5 × 106 CD34+ Cells/Kg in 4 days40.39.6<0.001% Patients achieving ≥2 × 106 CD34+ Cells/Kg in 2 days67.521.9<0.001% Patients achieving ≥5 × 106 CD34+ Cells/Kg in 2 days23.44.1<0.001*Values represent Median (Range)#Expressed as a ratio of the pre-G-CSF CD34+ cells/μL on Day 5 to pre-G-CSF CD34+ cells/μL on Day 4 Conclusions:Plerixafor + G-CSF allowed collection of the minimal transplantable cell dose in 78% patients with PB CD34+ cells/μl <10. These data show that adding plerixafor to G-CSF substantially reduces the risk of mobilization failure in patients with NHL predicted to be poor mobilizers based on low PB CD34+ cell counts. Thus, mobilization with plerixafor + G-CSF in patients with PB CD34+ cells/μl <10 increases stem cell collection efficiency allowing patients to pursue auto-HSCT with more optimal cell doses. Disclosures:Maziarz:Genzyme Corp.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Micallef:Genzyme Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding. Stiff:Genzyme Corp.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Bolwell:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Marulkar:Genzyme Corporation: Employment, Equity Ownership. Calandra:Genzyme Corporation: Consultancy, Equity Ownership. DiPersio:Genzyme Corporation: Honoraria.

Successful Stem Cell Remobilization Using Plerixafor (Mozobil) Plus Granulocyte Colony-Stimulating Factor in Patients with Non-Hodgkin Lymphoma: Results from the Plerixafor NHL Phase 3 Study Rescue Protocol

In a phase 3 multicenter, randomized, double-blinded, placebo-controlled study of 298 patients with non-Hodgkin lymphoma (NHL), granulocyte colony-stimulating factor (G-CSF) plus plerixafor increased the proportion of patients who mobilized >or=5 x 10(6) CD34(+) hematopoietic stem cells (HSCs)/kg compared with placebo plus G-CSF (P < .001). Patients in either study arm who failed mobilization (< 0.8 x 10(6) CD34(+) cells/kg in 2 collections or <2 x 10(6) CD34(+) cells/kg in 4 collections) were eligible to enter the opened-label rescue protocol. Following a 7-day minimum rest period, these patients received G-CSF (10 microg/kg/day) for 4 days, followed by daily plerixafor (0.24 mg/kg) plus G-CSF and apheresis for up to 4 days. Of the 68 patients failing initial mobilization (plerixafor, n = 11; placebo, n = 57), 62 patients (91%) entered the rescue procedure (plerixafor, n = 10; placebo, n = 52). Four of 10 patients (40%) from the plerixafor group and 33 of 52 (63%) from the placebo group mobilized sufficient CD34(+) cells (>or= 2 x 10(6) cells/kg) for transplantation from the rescue mobilization alone (P = .11). Engraftment of neutrophils (11 days) and platelets (20 days) was similar to that in patients who did not fail initial mobilization, and all patients had durable grafts at the 12-month follow-up. Common plerixafor-related adverse events (AEs) included mild gastrointestinal (GI) effects and injection site reactions. There were no drug-related serious AEs. These data support that plerixafor plus G-CSF can safely and effectively remobilize patients with NHL who have failed previous mobilization.

INVOLVEMENT OF UROKINASE-TYPE PLASMINOGEN ACTIVATOR RECEPTOR IN HEMATOPOIETIC STEM CELL MOBILIZATION (81.7)

Abstract Cleaved forms of soluble urokinase-receptor (c-suPAR) have been detected in body fluids from patients affected by various tumors. We reported increased c-suPAR levels in sera of healthy donors during granulocyte colony-stimulating factor (G-CSF)-induced mobilization of CD34+hematopoietic stem cells (HSCs). Then, we investigated the effects of uPAR84–95, a c-suPAR-derived chemotactic peptide, on mobilization of mouse CD34+ hematopoietic stem/progenitor cells (HSCs/HPCs). We first demonstrated that uPAR84–95 stimulated in vitro dose-dependent migration of mouse CD34+ M1 leukemia cells and inactivated CXCR4, the chemokine receptor primarily responsible for HSC retention in bone marrow (BM). uPAR84–95 intraperitoneal administration induced rapid leukocytosis, which was associated with an increase in peripheral blood CD34+ HSCs/HPCs. In vitro colony assays confirmed that uPAR84–95 mobilized hematopoietic progenitors, showing an absolute increase in circulating colony-forming cells. uPAR84–95 mobilizing activity was comparable to that of G-CSF; however, neither synergistic nor additive effect was observed combining the two molecules. These findings demonstrate for the first time in vivo biological effects of c-suPAR. Its capability to mobilize HSCs suggests potential clinical applications in HSC transplantation.

AMD3100 with G-CSF for Autologous Peripheral Blood Progenitor Cell (PBPC) Mobilization in Non-Hodgkin's Lymphoma (NHL) and Multiple Myeloma (MM): Mobilization, Engraftment, and Pharmacokinetics (PK).

Background: AMD3100 potentiates the effect of G-CSF (Filgrastim) to mobilize hematopoietic PBPCs from the bone marrow into peripheral blood (PB) and may decrease the number of aphereses required to collect sufficient PBPCs for transplantation.Methods: Mobilization treatment consisted of subcutaneous G-CSF 10 ug/kg given in the morning on 5 consecutive days and a single dose of AMD3100 240 ug/kg in the evening of day 4, 10 – 11 hours prior to leukapheresis. These doses of G-CSF and AMD3100 were continued for up to 4 additional days in order to reach the target of ≥ 5 × 10^6 CD34+ cells/kg. Blood samples for FACS analysis of CD34+ cells were obtained immediately prior to dosing with AMD3100 and pre-apheresis the next morning. PK parameters were determined from samples obtained immediately prior to dosing, 0.25, 0.5, 1, 2, 4, 6 and 8 hours after the injection of AMD3100, and just prior to apheresis.Clinical Results: Nineteen pts have thus far been enrolled, 11 MM and 8 relapsed NHL. AMD3100 was well tolerated. Mobilization characteristics are summarized in table 1; 100% of MM pts and 63% of NHL pts reached the target of 5 × 10^6 CD34+ cells/kg; all collected > 2 ×10^6 CD34+ cells/kg. For apheresis day 1, AMD3100 increased absolute CD34+ counts ≥ 2-fold in 100% of pts; the median increase for MM pts was 3-fold (range: 2–7.7 fold) or an absolute increase of 108 CD34+ cells/uL (range: 40–166), whereas the median increase for NHL pts was 2.7-fold (range: 2.2–3.7 fold) or an absolute increase of 35.5 CD34+ cells/uL (range: 11–99). Among the relapsed NHL pts, who were characterized by lower pre-AMD3100 CD34+ counts, 4 had increase in PB CD34+ cells/ul from < 20 to > 20 and one other increased from 6 to 17. Of the 17 pts who have subsequently been transplanted; median time to engraftment of neutrophils >0.5 ×10^9/L and platelets >20 ×10^9/L was 11 and 18 days, respectively.PK Results: PK determinations for AMD3100 were completed in a subset of patients (4 MM; 3 NHL) using plasma samples obtained after the first dose. AMD3100 was rapidly absorbed following subcutaneous injection with a median tmax of 30 (range, 15–60) minutes and Cmax of 0.84 (range, 0.77–1.03) ug/ml. Plasma concentrations declined in a bi-exponential manner, with a median elimination half-life of 4.6 (range, 2.71–5.32) hours. The median AUC 0-infinity was 4410 (range, 2682–5165) ug-hr/ml. AMD3100 pharmacokinetics were consistent with results previously obtained in studies conducted using healthy volunteers in the absence of G-CSF.Conclusions:AMD3100 was generally safe and well tolerated in both groups.PK in the cancer patients was similar to that in previously studied healthy volunteers.AMD3100 increased PBPC mobilization following 4 days of G-CSF, and resulted in collecting large numbers of PBPCs in MM patients and facilitated adequate PBPC collections for poor mobilizers within the relapsed NHL group.Table 1:Mobilization characteristicsNo. of ptsNo. apheresis days (range)Median CD34+ cells collected (×10^6/kg)>2×10^6/kg collected on day 1>5×10^6/kg collected on day 1MM111 (1–2)13.1 (5.8–19.7)100%82%NHL82 (1–5)5.6 (2.8–10.6)88%50%All191 (1–5)9.0 (2.8–19.7)95%68%

In vivo Activity of the Cleaved Form of Soluble Urokinase Receptor: A New Hematopoietic Stem/Progenitor Cell Mobilizer

Cleaved forms of soluble urokinase receptor (c-suPAR) have been detected in body fluids from patients affected by various tumors. We recently reported increased c-suPAR levels in sera of healthy donors during granulocyte colony-stimulating factor (G-CSF)-induced mobilization of CD34(+) hematopoietic stem cells (HSC). In vitro, c-suPAR or its derived chemotactic peptide (uPAR(84-95)) stimulated migration of human CD34(+) HSCs and inactivated CXCR4, the chemokine receptor primarily responsible for HSC retention in bone marrow. These results suggested that c-suPAR could potentially contribute to regulate HSC trafficking from and to bone marrow. Therefore, we investigated uPAR(84-95) effects on mobilization of mouse CD34(+) hematopoietic stem/progenitor cells (HSC/HPC). We first showed that uPAR(84-95) stimulated in vitro dose-dependent migration of mouse CD34(+) M1 leukemia cells and inactivated murine CXCR4. uPAR(84-95) capability to induce mouse HSC/HPC release from bone marrow and migration into the circulation was then investigated in vivo. uPAR(84-95) i.p. administration induced rapid leukocytosis, which was associated with an increase in peripheral blood CD34(+) HSCs/HPCs. In vitro colony assays confirmed that uPAR(84-95) mobilized hematopoietic progenitors, showing an absolute increase in circulating colony-forming cells. uPAR(84-95) mobilizing activity was comparable to that of G-CSF; however, neither synergistic nor additive effect was observed in combining the two molecules. These findings show for the first time in vivo biological effects of c-suPAR. Its capability to mobilize HSCs suggests potential clinical applications in HSC transplantation.

Expansion of Bone Marrow (BM) Progenitors and Mobilization of Multilineage Progenitor Cells Associated with Once Per Cycle Administration of Long-Acting Growth Factors Neulasta and Aranesp with Chemotherapy (CT): Biology and Nature of Response.

Hematopoietic growth factors (HGF) G-CSF and GM-CSF have been utilized widely to facilitate mobilization of progenitor cells that can be used to support high dose CT. Recently long-acting HGF neulasta (pegfilgrastim) and aranesp (darbepoetin alfa) were developed to reduce the frequency of administration. While these agents are effective in reducing CT-induced neutropenia and anemia similar to their parent compounds, very little is known about their efficiency in mobilizing progenitor cells. The purpose of this study was to evaluate biologic effects of these agents, used in combination with CT, on progenitor cells. Chemo-naïve sarcoma patients receiving adriamycin and ifosfamide (AI) were treated once per cycle with aranesp (500 mcg) SC prior to initiating CT (day 0) and neulasta (6 mg) SC after completion of CT (day 4). BM and peripheral blood (PB) samples were studied at the baseline and around day 14 (at the time of WBC recovery) for progenitors and mediators of response. The treatment was associated with a significant increase in PB CD 34 + cells (median increase 36-fold, p=0.005) and marked mobilization (p=0.003) of CFU-GM (24-fold), BFU-E (22-fold), and CFU-GEMM (62-fold) (n=14). To better understand the biology and nature of response, we examined BM before and at the time of mobilization (n=12). There was an expansion of multi-lineage BM progenitors (p=0.06) and CD 34+ cells (P=0.001). BM exam at the time of recovery showed increased cellularity (2-fold) with increased granulopoietic elements. An increased expression of MMP-9 but unchanged expression of TIMP-1 was observed by Immunohistochemistry (IHC). c-kit ligand level by Elisa was decreased in the BM supernatant. In addition, phospho c-kit (phospho site 568) was increased in the myeloid and erythroid precursors by IHC but phospho site 823 was unaltered, indicating the specificity of activation of the downstream pathway in response to c-kit ligand-receptor activation, possibly leading to expansion of progenitor cells. Interestingly, expression of CXCR4 at the protein level (flow cytometry and western blot) and RNA level (RT-PCR) was decreased (p<0.05) in the BM at the time of mobilization (day 14) as compared to the baseline. These findings indicate that long-acting HGFs, administered once per cycle of CT, are a potent stimulus for mobilization of myeloid, erythroid, and multipotential progenitors. Our findings also suggest that increased myelopiesis in the regenerating BM may be associated with increased protease activity such as MMP-9 that may result in the cleavage of c-kit leading to activation of c-kit receptors and expansion of progenitors, and the cleavage of CXCR-4 leading to release of progenitors from the BM anchorage and mobilization into PB.

Mobilization of hematopoietic progenitor cells in healthy volunteers by AMD3100, a CXCR4 antagonist

AbstractStromal cell-derived factor 1 (SDF1/CXCL12) and its cognate receptor, CXCR4, play key regulatory roles in CD34+ cell trafficking. We investigated whether AMD3100, a selective CXCR4 antagonist, could mobilize hematopoietic progenitor cells from marrow to peripheral blood in healthy human volunteers. Initially, 10 persons each received a single dose of AMD3100 (80 μg/kg subcutaneously), which induced rapid, generalized leukocytosis associated with an increase in peripheral blood CD34+ cells, representing pluripotent hematopoietic progenitors by in vitro colony-forming unit assays, from 3.8 ± 0.5/μL to 20.7 ± 3.5/μL at 6 hours. Subsequent dose-response studies showed a maximum increase in circulating CD34+ cells from 2.6 ± 0.3/μL to 40.4 ± 3.4/μL at 9 hours after 240 μg/kg AMD3100. Serial administration of AMD3100 (80 μg/kg/d for 3 days) resulted in consistent, reversible increases in peripheral blood CD34+ cells. AMD3100 was well tolerated and caused only mild, transient toxicity. These findings suggest potential clinical application of AMD3100 for CD34+ cell mobilization and collection for hematopoietic stem cell transplantation.

Granulocyte colony-stimulating factor recruitment of CD34+ progenitors to peripheral blood: impaired mobilization in chronic granulomatous disease and adenosine deaminase--deficient severe combined immunodeficiency disease patients

Peripheral blood (PB) CD34+ cells mobilized by granulocyte colony- stimulating factor (G-CSF) administration are potentially useful for transplantation and as a target of gene transfer for therapy of hematopoietic disorders. Efficient harvest and planning for clinical use of PB CD34+ cells ideally requires foreknowledge of the expected mobilization kinetics and yield. We developed a sensitive flow cytometric assay for accurately enumerating CD34+ cells throughout the range seen at baseline to peak mobilization. We used this assay to assess the kinetics of G-CSF-mediated mobilization of CD34+ cells to PB in normal volunteers and in patients with chronic granulomatous disease (CGD) or adenosine deaminase (ADA)-deficient severe combined immunodeficiency disease (SCID). Two dose levels of G-CSF were examined (5 and 10 micrograms/kg/d for 7 days). Both doses were well tolerated. For normal subjects and patients an increase in PB CD34+ cells was first detected only preceding the third dose of G-CSF (day 3), peaked transiently on day 5 or 6, and then decreased thereafter despite additional doses of G-CSF. With 32 normal volunteers mean peak CD34+ cell counts were 57 and 76 cells/mm2 of blood (5 and 10 micrograms doses, respectively), whereas for 18 CGD patients the mean peaks were 31 and 40 cells/mm2 of blood. For 2 ADA-deficient SCID patients studied at a G-CSF dose of 5 micrograms/kg/d, the average peak was 16 cells/mm2 of blood. For both of these patient groups mobilization of CD34+ cells to PB was impaired compared with similarly treated normal subjects (P &lt; .05). By contrast to the kinetics of the CD34+ cell mobilization, the absolute neutrophil count (ANC) increased markedly by 6 hours after the first dose of G-CSF and then increased steadily through day 8. At days 5 and 6 (peak mobilization of CD34+ cells) the mean ANC of CGD and ADA patients was only slightly lower ( &lt; or = 15%) than that seen with normal subjects, whereas the difference in CD34+ cell mobilization was &gt; 48%. Thus, ANC is not a reliable surrogate to predict peak PB CD34+ cell counts and direct enumeration of PB CD34+ counts should be undertaken in decisions regarding timing and duration of apheresis to harvest a specific number of these cells. Finally, unexpected, but significant differences in the PB CD34+ cell mobilization between normal subjects and patients with inherited disorders can occur and underscores the importance of establishing the expected mobilization of PB CD34+ cells in the planning of treatment approaches using these cells.

Granulocyte Colony-Stimulating Factor Recruitment of CD34+ Progenitors to Peripheral Blood: Impaired Mobilization in Chronic Granulomatous Disease and Adenosine Deaminase-Deficient Severe Combined Immunodeficiency Disease Patients

Peripheral blood (PB) CD34+ cells mobilized by granulocyte colony-stimulating factor (G-CSF) administration are potentially useful for transplantation and as a target of gene transfer for therapy of hematopoietic disorders. Efficient harvest and planning for clinical use of PB CD34+ cells ideally requires foreknowledge of the expected mobilization kinetics and yield. We developed a sensitive flow cytometric assay for accurately enumerating CD34+ cells throughout the range seen at baseline to peak mobilization. We used this assay to assess the kinetics of G-CSF-mediated mobilization of CD34+ cells to PB in normal volunteers and in patients with chronic granulomatous disease (CGD) or adenosine deaminase (ADA)-deficient severe combined immunodeficiency disease (SCID). Two dose levels of G-CSF were examined (5 and 10 micrograms/kg/d for 7 days). Both doses were well tolerated. For normal subjects and patients an increase in PB CD34+ cells was first detected only preceding the third dose of G-CSF (day 3), peaked transiently on day 5 or 6, and then decreased thereafter despite additional doses of G-CSF. With 32 normal volunteers mean peak CD34+ cell counts were 57 and 76 cells/mm2 of blood (5 and 10 micrograms doses, respectively), whereas for 18 CGD patients the mean peaks were 31 and 40 cells/mm2 of blood. For 2 ADA-deficient SCID patients studied at a G-CSF dose of 5 micrograms/kg/d, the average peak was 16 cells/mm2 of blood. For both of these patient groups mobilization of CD34+ cells to PB was impaired compared with similarly treated normal subjects (P < .05). By contrast to the kinetics of the CD34+ cell mobilization, the absolute neutrophil count (ANC) increased markedly by 6 hours after the first dose of G-CSF and then increased steadily through day 8. At days 5 and 6 (peak mobilization of CD34+ cells) the mean ANC of CGD and ADA patients was only slightly lower ( < or = 15%) than that seen with normal subjects, whereas the difference in CD34+ cell mobilization was > 48%. Thus, ANC is not a reliable surrogate to predict peak PB CD34+ cell counts and direct enumeration of PB CD34+ counts should be undertaken in decisions regarding timing and duration of apheresis to harvest a specific number of these cells. Finally, unexpected, but significant differences in the PB CD34+ cell mobilization between normal subjects and patients with inherited disorders can occur and underscores the importance of establishing the expected mobilization of PB CD34+ cells in the planning of treatment approaches using these cells.