Plerixafor (Mozobil ®)Plus G-CSF Is Effective in Mobilizing Hematopoietic Stem Cells in Patients with Concurrent Thrombocytopenia Undergoing Autologous Hematopoietic Stem Cell Transplantation.

Abstract Abstract 3229 Poster Board III-166 Introduction Low platelet count prior to mobilization is a significant predictive factor for mobilization failure in patients with non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD) undergoing autologous hematopoietic stem cell (HSC) transplantation (auto-HSCT; Hosing C, et al, Am J Hematol. 2009). The purpose of this study is to assess the efficacy of HSC mobilization with plerixafor plus G-CSF in patients with concomitant thrombocytopenia undergoing auto-HSCT. Methods Patients who had failed successful HSC collection with any mobilization regimen were remobilized with plerixafor plus G-CSF as part of a compassionate use program (CUP). Mobilization failure was defined as the inability to collect 2 ×106 CD34+ cells/kg or inability to achieve a peripheral blood count of ≥10 CD34+ cells/μl without having undergone apheresis. As part of the CUP, G-CSF (10μg/kg) was administered subcutaneously (SC) every morning for 4 days. Plerixafor (0.24 mg/kg SC) was administered in the evening on Day 4, approximately 11 hours prior to the initiation of apheresis the following day. On Day 5, G-CSF was administered and apheresis was initiated. Plerixafor, G-CSF and apheresis were repeated daily until patients collected the minimum of 2 × 106 CD34+ cells/kg for auto-HSCT. Patients in the CUP with available data on pre-mobilization platelet counts were included in this analysis. While patients with a platelet count <85 × 109/L were excluded from the CUP, some patients received waivers and were included in this analysis. Efficacy of remobilization with plerixafor + G-CSF was evaluated in patients with platelet counts ≤ 100 × 109/L or ≤ 150 × 109/L. Results Of the 833 patients in the plerixafor CUP database, pre-mobilization platelet counts were available for 219 patients (NHL=115, MM=66, HD=20 and other=18.). Of these, 92 patients (NHL=49, MM=25, HD=8 and other=10) had pre-mobilization platelet counts ≤ 150 × 109/L; the median platelet count was 115 × 109/L (range, 50-150). The median age was 60 years (range 20-76) and 60.4% of the patients were male. Fifty-nine patients (64.1%) collected ≥2 × 109 CD34+ cells/kg and 13 patients (14.1%) achieved ≥5 × 106 CD34+ cells/kg. The median CD34+ cell yield was 2.56 × 106 CD34+ cells/kg. The proportion of patients proceeding to transplant was 68.5%. The median time to neutrophil and platelet engraftment was 12 days and 22 days, respectively. Similar results were obtained when efficacy of plerixafor + G-CSF was evaluated in 29 patients with platelet counts ≤ 100 × 109/L (NHL=12, MM=10, HD=3 and other=4). The median platelet count in these patients was 83 × 109/L (range, 50-100). The median age was 59 years (range 23-73) and 60.4% of the patients were male. The minimal and optimal cell dose was achieved in 19(65.5%) and 3(10.3%) patients, respectively. The median CD34+ cell yield was 2.92 × 106 CD34+ cells/kg. The proportion of patients proceeding to transplant was 62.1%. The median time to neutrophil and platelet engraftment was 12 days and 23 days, respectively. Conclusions For patients mobilized with G-CSF alone or chemotherapy ±G-CSF, a low platelet count prior to mobilization is a significant predictor of mobilization failure. These data demonstrate that in patients with thrombocytopenia who have failed prior mobilization attempts, remobilization with plerixafor plus G-CSF allows ∼65% of the patients to collect the minimal cell dose to proceed to transplantation. Thus, in patients predicted or proven to be poor mobilizers, addition of plerixafor may increase stem cell yields. Future studies should investigate the efficacy of plerixafor + G-CSF in front line mobilization in patients with low platelet counts prior to mobilization. Disclosures Micallef: Genzyme Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding. Jacobsen:Genzyme Corporation: Research Funding. Shaughnessy:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Marulkar:Genzyme Corporation: Employment, Equity Ownership. Mody:Genzyme Corporation: Employment, Equity Ownership. van Rhee:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Lower Hematopoietic Progenitor Cell Counts and Yields at Subsequent Donations Is Influenced By a Shorter Inter-Donation Interval between the First and Subsequent Mobilizations

Blood ◽

10.1182/blood-2019-123492 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1962-1962

Author(s):

Sandhya R. Panch ◽

Brent R. Logan ◽

Jennifer A. Sees ◽

Bipin N. Savani ◽

Nirali N. Shah ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Peripheral Blood ◽

Research Funding ◽

Time Interval ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Peripheral Blood Cd34 ◽

Cell Counts ◽

Cd34 Cells

Introduction: Approximately 7% of unrelated hematopoietic stem cell (HSC) donors are asked to donate a subsequent time to the same or different recipient. In a recent large CIBMTR study of second time donors, Stroncek et al. incidentally found that second peripheral blood stem cell (PBSC) collections had lower total CD34+ cells, CD34+ cells per liter of whole blood processed, and CD34+ cells per kg donor weight. Based on smaller studies, the time between the two independent PBSC donations (inter-donation interval) as well as donor sex, race and baseline lymphocyte counts appear to influence CD34+ cell yields at subsequent donations. Our objective was to retrospectively evaluate factors contributory to CD34+ cell yields at subsequent PBSC donation amongst NMDP donors. Methods. The study population consisted of filgrastim (G-CSF) mobilized PBSC donors through the NMDP/CIBMTR between 2006 and 2017, with a subsequent donation of the same product. evaluated the impact of inter-donation interval, donor demographics (age, BMI, race, sex, G-CSF dose, year of procedure, need for central line) and changes in complete blood counts (CBC), on the CD34+ cell yields/liter (x106/L) of blood processed at second donation and pre-apheresis (Day 5) peripheral blood CD34+ cell counts/liter (x106/L) at second donation. Linear regression was used to model log cell yields as a function of donor and collection related variables, time between donations, and changes in baseline values from first to second donation. Stepwise model building, along with interactions among significant variables were assessed. The Pearson chi-square test or the Kruskal-Wallis test compared discrete variables or continuous variables, respectively. For multivariate analysis, a significance level of 0.01 was used due to the large number of variables considered. Results: Among 513 PBSC donors who subsequently donated a second PBSC product, clinically relevant decreases in values at the second donation were observed in pre-apheresis CD34+ cells (73.9 vs. 68.6; p=0.03), CD34+cells/L blood processed (32.2 vs. 30.1; p=0.06), and total final CD34+ cell count (x106) (608 vs. 556; p=0.02). Median time interval between first and second PBSC donations was 11.7 months (range: 0.3-128.1). Using the median pre-apheresis peripheral blood CD34+ cell counts from donation 1 as the cut-off for high versus low mobilizers, we found that individuals who were likely to be high or low mobilizers at first donation were also likely to be high or low mobilizers at second donation, respectively (Table 1). This was independent of the inter-donation interval. In multivariate analyses, those with an inter-donation interval of >12 months, demonstrated higher CD34+cells/L blood processed compared to donors donating within a year (mean ratio 1.15, p<0.0001). Change in donor BMI was also a predictor for PBSC yields. If donor BMI decreased at second donation, so did the CD34+cells/L blood processed (0.74, p <0.0001). An average G-CSF dose above 960mcg was also associated with an increase in CD34+cells/L blood processed compared to donors who received less than 960mcg (1.04, p=0.005). (Table 2A). Pre-apheresis peripheral blood CD34+ cells on Day 5 of second donation were also affected by the inter-donation interval, with higher cell counts associated with a longer time interval (>12 months) between donations (1.23, p<0.0001). Further, independent of the inter-donation interval, GCSF doses greater than 960mcg per day associated with higher pre-apheresis CD34+ cells at second donation (1.26, p<0.0001); as was a higher baseline WBC count (>6.9) (1.3, p<0.0001) (Table 2B). Conclusions: In this large retrospective study of second time unrelated PBSC donors, a longer inter-donation interval was confirmed to be associated with better PBSC mobilization and collection. Given hematopoietic stem cell cycling times of 9-12 months in humans, where possible, repeat donors may be chosen based on these intervals to optimize PBSC yields. Changes in BMI are also to be considered while recruiting repeat donors. Some of these parameters may be improved marginally by increasing G-CSF dose within permissible limits. In most instances, however, sub-optimal mobilizers at first donation appear to donate suboptimal numbers of HSC at their subsequent donation. Disclosures Pulsipher: CSL Behring: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Research Funding; Bellicum: Consultancy; Amgen: Other: Lecture; Jazz: Other: Education for employees; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Medac: Honoraria. Shaw:Therakos: Other: Speaker Engagement.

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Final Results from an International, Multi-Center, Single-Arm Study Evaluating the Safety and Efficacy of Romiplostim in Adults with Primary Immune Thrombocytopenia (ITP),

Blood ◽

10.1182/blood.v118.21.3279.3279 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3279-3279 ◽

Cited By ~ 6

Author(s):

Ann Janssens ◽

Michael D. Tarantino ◽

Robert Bird ◽

Maria Gabriella Mazzucconi ◽

Ralph Vincent V. Boccia ◽

...

Keyword(s):

Bone Marrow ◽

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

Platelet Response ◽

Employment Equity ◽

Advisory Committees ◽

Platelet Production ◽

Platelet Counts ◽

Equity Ownership

Abstract Abstract 3279 Background: ITP is an autoimmune disorder characterized by increased platelet destruction and suboptimal platelet production. Romiplostim stimulates platelet production via the TPO-receptor, and is recommended for second- and third-line treatment of chronic ITP in adults. We report final data from a large prospective study of romiplostim in adults with ITP of varying duration and severity. Methods: Eligibility criteria were broad: patients ≥18 years of age, who had received prior ITP therapies (final protocol amendment: ≥1, previous amendments: ≥3), with low platelet counts (final amendment: ≤ 30 × 109/L, previous amendments: ≤ 10, ≤ 20 × 109/L) or experiencing uncontrolled bleeding. The only excluded comorbidities were: hematological malignancy, myeloproliferative neoplasms, MDS and bone marrow stem cell disorder. Romiplostim was initiated at 1 (final amendment) or 3 (previous amendments) μg/kg/week, with dose adjustments allowed to maintain platelet counts ≥50 × 109/L. Patients could continue on study until they had access to commercially available romiplostim. Rescue medications were allowed at any time; concurrent ITP therapies could be reduced when platelet counts were > 50 × 109/L. Primary endpoint was incidence of adverse events (AEs) and antibody formation. Secondary endpoint was platelet response, defined as either (1) doubling of baseline count and ≥ 50 × 109/L or (2) ≥20 × 109/L increase from baseline. Results: A total of 407 patients received romiplostim, 60% of whom were female. Median (Q1, Q3) time since ITP diagnosis was 4.25 (1.20, 11.40) years (maximum 57.1 years), with 51% of patients splenectomised and 39% receiving baseline concurrent ITP therapies. Seventy-one percent of patients completed the study, with requirement for alternative therapy and withdrawn consent the most common reasons for discontinuation (5% each). Median (Q1, Q3) on-study treatment duration was 44.29 (20.43, 65.86) weeks (maximum 201 weeks), with a total of 20,201 subject-weeks on study. Incidence and type of AEs were consistent with previous studies. The most common serious treatment-related AEs were cerebrovascular accident, headache, bone marrow reticulin fibrosis (with no evidence of positive trichrome staining for collagen and no evidence suggesting primary idiopathic myelofibrosis), nausea, deep vein thrombosis, hemorrhage and pulmonary embolism, with each reported in 2 of 407 (0.5%) patients. All other serious treatment-related AEs were each reported in one patient. Eighteen patients died; 3 deaths (hemolysis, intestinal ischaema, aplastic anemia) were considered treatment-related. No neutralizing antibodies to romiplostim or TPO were reported. Approximately 90% of patients achieved each of the platelet response definitions, regardless of splenectomy status. Overall, median (Q1, Q3) time to response was 2 (1, 4) weeks for response definition 1, and 1 (1, 3) week for response definition 2. Median (Q1, Q3) baseline platelet count was 14 (8, 21) × 109/L. After 1 week of treatment median (Q1, Q3) platelet count had increased to 42 (18, 101) × 109/L. From week 8 onwards, and excluding counts within 8 weeks of rescue medication use, median platelet counts were consistently above 100 × 109/L (range 101.0–269.5 × 109/L). Median (Q1, Q3) average weekly romiplostim dose was 3.62 (1.99, 6.08) μg/kg. Summary/conclusions: This is the largest prospective study in adult ITP reported to date. The data reported here are similar to those reported for previous romiplostim studies, with romiplostim able to safely induce a rapid platelet response in adult ITP patients with low platelet counts or bleeding symptoms. Romiplostim is an important, well-tolerated, treatment option for adult ITP patients, which significantly increases and maintains platelet counts. Adverse Event Subject Incidence Platelet Response Disclosures: Janssens: Amgen: Consultancy; Roche: Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees. Tarantino:Cangene corporation: Research Funding; Baxter: Research Funding; Talecris: Honoraria, Speakers Bureau; Up-to-date: Patents & Royalties; The Bleeding and Clotting Disorders Institute: Board Member. Bird:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees. Boccia:Amgen: Equity Ownership, Honoraria, Speakers Bureau. Lopez-Fernandez:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kozak:Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Steurer:Amgen: Honoraria. Dillingham:Amgen Limited: Employment, Equity Ownership. Lizambri:Amgen: Employment, Equity Ownership.

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Thromboembolic Events Observed in Eltrombopag Clinical Trials in Chronic Immune Thrombocytopenic Purpura.

Blood ◽

10.1182/blood.v114.22.2423.2423 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2423-2423 ◽

Cited By ~ 8

Author(s):

James B. Bussel ◽

Gregory Cheng ◽

Mansoor N. Saleh ◽

Sandra Vasey ◽

Manuel Aivado ◽

...

Keyword(s):

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

Thromboembolic Events ◽

Study Medication ◽

Normal Range ◽

Advisory Committees ◽

Thrombocytopenic Purpura ◽

Platelet Counts ◽

Equity Ownership

Abstract Abstract 2423 Poster Board II-400 BACKGROUND: Eltrombopag (PROMACTA®; GlaxoSmithKline, Collegeville, PA, USA), an oral, small molecule, thrombopoietin receptor agonist, was recently approved in the United States for the treatment of patients with chronic immune thrombocytopenic purpura (ITP). Limited published data indicate that patients with chronic ITP experience thromboembolic events (TEEs) with a frequency of 3% to 6%. (Aledort, Am J Hematol, 2004; Bennett, Haematologica, 2008). OBJECTIVE: To evaluate the incidence of TEEs in patients with chronic ITP treated with eltrombopag and to determine if the occurrence of TEEs was associated with elevated platelet counts. METHODS: Data from 446 patients from 3 placebo-controlled eltrombopag studies (TRA100773A, TRA100773B, and RAISE) and 2 open-label studies (REPEAT and EXTEND) were analyzed. The frequency of TEEs or suspected TEEs before and after the first dose of study medication (placebo or eltrombopag) was examined across the program. Potential risk factors, including platelet counts proximal to the event, were evaluated in patients experiencing a TEE. RESULTS: Prior to the initiation of study medication (placebo or eltrombopag), 16/493 (3.2%) of the patients entering the program had a history of TEEs (one of these patients experienced 2 additional TEEs [TIA, MI] while on treatment with eltrombopag). Across the ITP clinical program, 17/446 patients treated with eltrombopag (3.8%) experienced 22 TEEs. No patient treated with placebo experienced a TEE. The patient-years (PYs) of exposure to study medication was approximately 14 times greater for patients treated with eltrombopag compared to placebo (eltrombopag 377 PYs; placebo 26 PYs). Most patients (13/17) experienced 1 TEE; 3 patients experienced 2, and 1 patient experienced 3 (2 TEEs were 6 months off-therapy). The most common TEEs were deep vein thrombosis (n=8) and pulmonary embolism (n=6). A total of 18/22 events were resolved or resolving at the time of this analysis; all patients experiencing a TEE had at least 1 risk factor for these events other than ITP (eg, use of IVIg [n=3], hospitalization with no prophylactic anticoagulation [n=4], oral corticosteroids [n=6]). The platelet counts proximal to the event ranged from 14,000/μL to 420,000/μL. The majority of patients had platelet counts below 150,000/μL (9; 53%) or between 150,000/μL and 400,000/μL (5; 29%); 2 had platelet counts above 400,000/μL and the platelet count in 1 was unknown. All 446 patients were categorized by the maximum platelet count achieved during treatment with eltrombopag (above normal [>400,000/μL], normal range [150–400,000/μL], below normal range [<150,000/μ]; Table 1). The majority of patients (14; 82%) experienced the TEEs at a platelet count lower than their maximum platelet count, while 3 patients (18%) experienced a TEE proximal to their maximum platelet count. CONCLUSION: TEEs occurred with eltrombopag. None occurred with placebo; however, the PYs of exposure was considerably less with placebo than with eltrombopag. The frequency of TEEs observed during eltrombopag treatment (3.8%) is similar to that reported in the literature and prior to enrollment in the eltrombopag program (3.2%). No discernible correlation has been observed between platelet count increases and TEEs, and these events do not appear to be associated with maximum platelet counts during treatment with eltrombopag. Disclosures: Bussel: Sysmex: Research Funding; Eisai, Inc: Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; Amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; GlaxoSmithKline: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genzyme: Research Funding; Scienta: Speakers Bureau; Shionogi: Membership on an entity's Board of Directors or advisory committees. Cheng:GlaxoSmithKline: Research Funding. Saleh:GlaxoSmithKline: Speakers Bureau; Amgen: Speakers Bureau. Vasey:GlaxoSmithKline: Employment. Aivado:GlaxoSmithKline: Employment. Brainsky:GlaxoSmithKline: Employment.

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The Effect of Eltrombopag on Platelet Resistance to Apoptosis: The Role of the Bcl-Xl Pathway

Blood ◽

10.1182/blood.v118.21.1158.1158 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1158-1158

Author(s):

W. Beau Mitchell ◽

Michele N Edison ◽

Mariana P Pinheiro ◽

Nayla Boulad ◽

Bethan Psaila ◽

...

Keyword(s):

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

De Novo ◽

Apoptosis Resistance ◽

Advisory Committees ◽

Apoptotic Pathway ◽

Akt Activation ◽

Platelet Counts ◽

Equity Ownership

Abstract Abstract 1158 INTRODUCTION: Immune thrombocytopenia (ITP) is typically characterized by increased platelet destruction and reduced platelet production. Eltrombopag and Romiplostim are thrombopoietin receptor (TPO-R) agonists that are known to increase platelet counts in patients with ITP by stimulating thrombopoiesis. Platelets also express TPO-R on their surface, but it is unknown whether the thrombopoietin mimetics (TPO-M) have a direct effect on the circulating platelets. Although controversial, in a very small number of ITP patients, TPO-M agents may increase platelet counts in 2–5 days, earlier than would be expected from de novo megakaryocytopoiesis. Platelet survival is hypothesized to be mediated by two molecular intermediates in an apoptotic pathway, Bcl-xL and Bak. Bcl-xL/Bak protein expression in megakaryocytes is regulated in part by TPO-mediated activation of Akt pathways through Jak2 and Stat5. We hypothesized that an increase in platelet count in the first week of treatment might be mediated by TPO-R signaling, resulting in decreased platelet apoptosis. This study explored whether Eltrombopag or Romiplostim treatment has anti-apoptotic effects on platelets of patients with ITP. METHODS: Following a treatment wash out period, 75 mg of Eltrombopag once daily or 10 mcg/kg weekly of Romiplostim was initiated for 2 weeks. Blood counts were measured on days 1, 3, 5, 8, 10, 12, and 15. Platelet function and survival was assessed on days 1, 8, and 15 by: immature platelet fraction (IPF), glycocalicin index, Bcl-xL inhibitor (ABT-737) assay, measurement of Bcl-xL by western blot, measurement of several members of the Bcl-xL Akt mediated, apoptotic pathway by flow cytometry (FACS), bleeding score, measurement of thrombin-anti-thrombin complexes (TATs), and quantification of microparticles. RESULTS: Eight of 10 patients responded to treatment with Eltrombopag with a platelet count ≥ 50,000/μL, and 6 of the 8 responders at least doubled their counts during the 2 weeks of treatment. All 3 patients treated with Romiplostim responded with platelet count ≥ 50,000/μL. In both treatment groups there was a significant increase in median platelet count (p<0.001), median large platelet count (p<0.01), and median absolute IPF (A-IPF, p<0.01), while there was no significant change in median % IPF. The dose of ABT-737 required to kill half of the platelets in the sample (IC50) in the Eltrombopag group was lower in patients at day 1 than in non-ITP controls, and there was an increase in resistance to apoptosis between days 1 and 8, but these changes did not reach statistical significance. Between days 8 and 15 the IC50 declined to pre-treatment levels. In the Romiplostim group there was no significant difference in IC50 between the control and the patients over the 2 weeks of study. There was no significant correlation between the platelet counts and the IC50 values. FACS analysis of members of the AKT signal transduction pathway revealed increased activation of each of the markers between days 1 and 8, followed by a decrease between days 8 and 15. The levels of Bcl-xL and phosphor-AKT(308) decreased from day 1 to day 15. The other lab tests are pending. DISCUSSION: Because the A-IPF increased by less than the platelet increase and because the lifespan of the A-IPF is not known, it is unclear if the platelet count increase is solely a result of increased platelet production. Platelet lifespan may be enhanced by Eltrombopag treatment as there was a parallel albeit transient increase in AKT activation markers and platelet apoptosis resistance in the Eltrombopag group. Treatment with Romiplostim did not appear to affect apoptosis resistance although it did result in transient AKT activation. Our data suggest that platelets are more resistant to apoptosis when the levels of anti-apoptotic factors (eg. PTEN, Phospho-GSK3β) involved in the AKT/Bcl-xL pathway are greatest despite a concomitant increase in pro-apoptotic factors (eg. Bak, Bax). Since both the increased AKT activation and apoptotic resistance returned to baseline at day 15, megakaryocytes and platelets already present at the start of treatment may respond differently than those generated de novo in the presence of TPO mimetics. Disclosures: Bussel: Portola: Consultancy; Eisai: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; GlaxoSmithKline: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Cangene: Research Funding; Genzyme: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shionogi: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sysmex: Research Funding.

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Effects of Anti-Glycoprotein Antibodies on Response of Immune Thrombocytopenia Patients to Thrombopoietin Receptor Agonists and on Megakaryocytes Viability

Blood ◽

10.1182/blood.v126.23.1048.1048 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1048-1048

Author(s):

Marina Izak Karaev ◽

Alexandra Kruse ◽

Margaret Morrisey ◽

Heyu Ni ◽

Zhu Guangheng ◽

...

Keyword(s):

Platelet Count ◽

Board Of Directors ◽

Treatment Option ◽

Research Funding ◽

Immune Thrombocytopenia ◽

Advisory Committees ◽

Thrombopoietin Receptor Agonists ◽

Platelet Counts ◽

Thrombopoietin Receptor ◽

Equity Ownership

Abstract Background Immune Thrombocytopenia (ITP) is a bleeding disorder due to a combination of increased platelet destruction and reduced production, often secondary to anti-platelet/megakaryocyte antibodies. The presence of antibodies to glycoproteins (GP) IIb/IIIa (integrin αIIbβ3) and GPIb/IX, detected in majority of ITP patients, may correspond to different responses to treatment, i.e., anti-GPIb is associated with more severe disease, and less responsive to intravenous immunoglobulins and steroids. Thrombopoietin Receptor Agonists (TPO-RA) increase platelet production by stimulation of megakaryopoesis. Predictors of response to TPO-RA and influence of antibody profile on response are currently unknown. In our previous study we investigated Absolute Immature Platelet Fraction (A-IPF) prior to TPO-RA treatment and did not find a correlation between A-IPF, anti-GP antibodies, and platelet counts. The aims of this study were to further investigate: 1. The role of anti-GP antibodies in response to TPO-RA; 2. Effect of patients' antibodies on megakaryocyte (MK) viability, maturation, apoptosis and formation of proplatelets (in vitro); 3. The influence of patients' clinical characteristics on response to TPO-RA. Materials and Methods 91 patients with persistent or chronic ITP, were treated at Weill Medical College of Cornell University until January 2015 with TPO-RAs: 52 patients received eltrombopag, 22 romiplostim and 17 avatrombopag. Serum samples of 84 patients were analyzed for the presence of anti-GP by MAIPA assay as previously described. Patients with baseline platelet counts less than <30x109/L were defined as responders to TPO-RA if the average of their six median monthly platelet counts was ≥50x109/L and doubled from average baseline counts (prior to TPO-RA). Patients with baseline platelet counts 30-50x109/L were responders if the average platelet count was ≥75x109/L. MKs were derived from human umbilical cord blood stem cells as previously described. Cells were grown using SFEM medium, adding on day 0 of culture 50 ng/ml recombinant TPO and aliquots of serum of ITP patients or healthy controls. The percentages of immature (CD41+/CD42-), mature (CD41+/CD42+), viable and apoptotic MKs were analyzed by flow cytometry on day 12. Apoptosis was analyzed by measuring Mitochondrial Outer Membane Potential (MOMP) and Phosphatidyl Serine (PS) externalization. MKs were considered apoptotic if they had positive staining for PS externalization, viable if positive for MOMP, and dead if positive for 7-Aminoactinomycin D (7AAD). Proplatelet formation by MKs was analyzed by microscopy. Statistical analysis using unpaired T-test and Pearson correlation test were performed. Results Ninety-one patients were included, 40 male (44%) and 51 female (56%), with a median age of 37.4 years (range 2-87). Median duration of ITP before TPO-RA treatment was 8 years (range 0.3-45). The 18/91 (19.8%) non-responders to TPO-RA were not different from the 73/91 responders in age, gender, number of prior treatments, duration of ITP, and past splenectomy. The presence of either or both anti-GP antibodies was correlated with average lower platelet counts on TPO-RA: 82.3 x109/L versus 123x109/L in patients without detected antibodies ("neither") (p=0.003). However, the response to TPO-RA was not influenced by the type of antibody: in patients with anti-GPIb the average platelet count was 76.1x109/L, and with anti-GPIIb/IIIa 80.7x109/L (Figure 1). In culture, excess dead MKs were found in anti-GPIb group and antiGPIb&antiGPIIb/IIIa group compared to "neither" group (p=0.0013 and p=0.027 respectively) and comparing antiGPIb&antiGPIIb/IIIa to control (p=0.0025). We did not observe changes in the degree of MK apoptisis or in MK maturation in the presence of serum antibodies. In cultures treated with serum of patients having anti-GPIb, less proplatelets were detected comparing to control (p=0.044) or to "neither" (p=0.0039). We conclude that patients with anti-GP antibodies respond less to TPO-RA, however there is no difference in response to TPO-RA between patients having anti-GPIb and anti-GPIIb/IIIa, unlike responses to other treatment modalities (e.g., steroids or immunoglobulins). TPO-RA could be a preferable treatment option in ITP patients having anti-GPIb. Figure 1. Average 6-months platelet counts of TPO-RA-treated ITP patients divided into groups by presence of antibody/ies. Figure 1. Average 6-months platelet counts of TPO-RA-treated ITP patients divided into groups by presence of antibody/ies. Disclosures Off Label Use: Eltrombopag, romiplostim and avatrombopag are a thrombopoietin receptor agonist approved for the treatment of thrombocytopenia in adults with chronic ITP. In some preliminary studies these medicines found as safe and effective treatment option in children and adolescents. Bussel:amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; GlaxoSmithKline: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Novartis: Consultancy, Research Funding; Genzyme: Consultancy; BiologicTx: Research Funding; Ligand: Consultancy, Research Funding; Eisai: Consultancy, Research Funding; Shionogi: Consultancy, Research Funding; momenta: Consultancy; Protalex: Consultancy; Symphogen: Consultancy.

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Effect of Daratumumab-Containing Induction on CD34+ Hematopoietic Stem Cells before Autologous Stem Cell Transplantation in Multiple Myeloma

Blood ◽

10.1182/blood-2021-150360 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 2764-2764

Author(s):

Ondrej Venglar ◽

Tereza Sevcikova ◽

Anjana Anilkumar Sithara ◽

Veronika Kapustova ◽

Jan Vrana ◽

...

Keyword(s):

Multiple Myeloma ◽

Stem Cell ◽

Board Of Directors ◽

Research Funding ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Platelet Recovery ◽

Cd34 Cells ◽

Fcm Analysis ◽

D 12

Abstract Introduction: Daratumumab (Dara) is an anti-CD38 monoclonal antibody representing a novel treatment agent for multiple myeloma (MM). Nonetheless, several studies have reported a Dara-related impairment of CD34+ hematopoietic stem cell (HSC) mobilization and post-autologous stem cell transplantation (ASCT) complications, including low yields of mobilized HSCs and delayed neutrophil engraftment. Impact of Dara on the mobilization process and HSCs remains poorly understood even though sufficient yields of CD34+ cells are necessary for a successful ASCT and subsequent patient recovery. Aims: To compare the effect of the Dara-containing (Dara-Bortezomib-Dexamethasone [D-VCd]) and conventional (Bortezomib-Thalidomide-Dexamethasone [VTd]) therapy on CD34+ HSCs. Methods: Transplant eligible MM patients were treated with D-VCd or VTd induction regimen followed by a cyclophosphamide + G-CSF mobilization and a high-dose melphalan D -1 before ASCT. Flow cytometry (FCM) screening of CD34+ subsets was performed in the bone marrow (BM) or apheresis product (AP) at three consecutive time points: 1) diagnostic BM (DG), 2) mobilization AP (MOB), 3) a day prior ASCT BM (D-1). Furthermore, RNA sequencing (RNAseq) of sorted CD34+ cells was performed on total RNA with ribo-depletion protocol in AP after the induction. D-VCd samples had lower RNA yields thus the D-VCd or VTd groups were processed as independent batches. Results: Clinical data revealed no significant differences in mobilization (p >0.050) likely due to a small cohort sizes (D-VCd n=5 vs VTd n=9), though a trend towards worse performance in D-VCd was observed. Median CD34+ cell yield was 3.08 vs 10.56 x 10 6/kg. Platelet recovery of >20x10 9/L was D+14 vs D+12 (range: 11-18 vs 10-16). Neutrophil recovery of >0.5x10 9/L was D+12 in both groups (range: 11-17 vs 11-12). In FCM analysis, DG (n=14), MOB D-VCd (n=5) vs VTd (n=9), D-1 D-VCd (n=7) vs VTd (n=15) were compared. CD34+ frequency (Fig. 1A) difference in MOB D-VCd vs VTd was insignificant (median: 1.15% vs 1.89%), whereas CD34+ fraction dropped in D-1 D-VCd (median: 0.52% vs 0.72%, p=0.027), albeit there was no significant reduction in D-1 D-VCd vs initial DG (median: 0.52% vs 0.45%). Differences in the distribution of certain HSC subsets were detected in the CD34+ pool (Fig. 1B-E). Frequency of multipotent progenitors (MPPs) (Fig. 1B) was increased in MOB D-VCd (median: 82.1% vs 66.2%, p=0.004). Frequency of lympho-myeloid-primed progenitor + granulocyte-monocyte progenitor (LMPP+GMP) (Fig. 1C) subset was reduced in D-VCd in both MOB (median: 1.7% vs 16.9%, p=0.042) and D-1 (median: 5.3% vs 14.0%; p=0.026). Erythro-myeloid progenitors (EMPs) (Fig. 1D) were reduced in MOB D-VCd (median: 10.7% vs 19.5%, p=0.042), while the frequency of EMPs increased in D-1 D-VCd (median: 20.8% vs 12.4%, p=0.045). No considerable differences were found in the expression of adhesion molecules CD44/HCAM or CD184/CXCR4. CD38 was strongly diminished in the whole D-VCd CD34+ fraction of MOB and D-1. To understand whether the differences in the mobilization efficacy after D-VCd induction were reflected in the expression profile of mobilized CD34+ cells, differential expression analysis was performed. Overall 133 significantly deregulated genes (p<0.05; log fold change >(-)1) between cohorts (D-VCd n=5 vs VTd n=5) were revealed (Fig. 2). Pathway analysis showed cellular response and localization as the most deregulated categories. The list of deregulated genes contained 25% of non-coding RNAs, some of which were linked to a protein localization in the cell (RN7SL1/2). The expression of adhesion molecules was inspected independently. Out of 59 HSC hallmark genes, only 8 were significantly altered in D-VCd. Interestingly, the main homing molecule CXCR4 seemed to be downregulated in D-VCd, while integrins A3 and B4 were upregulated. Conclusions: Despite the limited cohort sizes, a prospective trend of delayed neutrophil and platelet recovery was observed after D-VCd therapy. FCM analysis revealed a significant reduction of CD34+ subsets responsible, among others, for a reconstitution of neutrophils and megakaryocytes. A strong signal in transcriptome data which would potentially explain differential mobilization in D-VCd cohort was not detected, nevertheless, several genes with adhesive/homing and stem cell differentiation function were indeed altered. The results warrant further investigation. Figure 1 Figure 1. Disclosures Hajek: BMS: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharma MAR: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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PETIT and PETIT 2: Treatment with Eltrombopag in 171 Children with Chronic Immune Thrombocytopenia (ITP)

Blood ◽

10.1182/blood.v124.21.1450.1450 ◽

2014 ◽

Vol 124 (21) ◽

pp. 1450-1450 ◽

Cited By ~ 1

Author(s):

James B. Bussel ◽

John D. Grainger ◽

Purificacion Garcia de Miguel ◽

Jenny M. Despotovic ◽

Franco Locatelli ◽

...

Keyword(s):

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

Employment Equity ◽

Advisory Committees ◽

Platelet Counts ◽

Chronic Itp ◽

Thrombopoietin Receptor ◽

Count Response ◽

Equity Ownership

Abstract Background: Eltrombopag (EPAG), an oral thrombopoietin receptor agonist, is approved for treating thrombocytopenia in adults with chronic immune thrombocytopenia (ITP) with insufficient response to prior therapy. Pooled data from 2 similarly designed, randomized, double-blind, placebo (PBO)-controlled studies investigating safety and efficacy of EPAG in pediatric ITP are presented here. Methods: Subjects aged 1 to <18 years with a confirmed diagnosis of persistent or chronic ITP and a platelet count <30 Gi/L at day 1 were randomized 2:1 to EPAG or PBO and stratified by age: 12–17 years (Cohort 1), 6–11 years (Cohort 2), and 1–5 years (Cohort 3). Subjects could continue baseline ITP medications. After the PBO-controlled randomized phase, subjects were permitted to complete 17 or 24 weeks of treatment with open-label (OL) EPAG. Dose was adjusted based on platelet counts to a maximum of 75 mg daily. Results: A total of 174 subjects were enrolled in both studies; 171 received ≥1 dose of EPAG. 159 subjects were randomized (intent-to-treat population), and 157 received ≥1 dose of randomized study treatment (safety population). In the randomized period, 3 EPAG and 1 PBO subject discontinued study treatment, of which 2 EPAG and 1 PBO discontinued due to adverse events (AEs). In the OL-EPAG period, an additional 14 EPAG subjects discontinued study treatment, 6 due to AEs. Males comprised 47% of the EPAG and PBO groups and 20% and 24% were East Asians, respectively. Most subjects (93%) were diagnosed with ITP for ≥12 months, and 13% were receiving ITP medications at baseline. The majority of subjects (81%) received ≥2 prior ITP therapies. Most subjects (59%) had a baseline platelet count <15 Gi/L. All 9 (6%) splenectomized subjects were randomized to the EPAG group. Randomized Period A higher proportion of EPAG versus PBO subjects (62% vs 24%; P < 0.001) achieved a response with platelet counts ≥50 Gi/L at least once between weeks 1–6 (Cohort 1, 64% vs 11%; Cohort 2, 64% vs 27%; Cohort 3, 54% vs 36%, respectively). At each week, a higher proportion of EPAG subjects had a response versus PBO (Fig. 1). A lower proportion of EPAG subjects (13%) received rescue treatment compared with PBO subjects (31%; P = 0.009). The odds of having World Health Organization (WHO) bleeding grades 1–4 (0.19; P = 0.011) and clinically significant (WHO grades 2–4) bleeding (0.29; P = 0.007) were lower for EPAG versus PBO subjects. EPAG-Only Period Sustained reduction or discontinuation of baseline ITP medications, primarily corticosteroids, was achieved by 50% of subjects; 81% of subjects had a platelet count response at least once; 52% (n = 80/154) had a platelet count response for ≥50% of assessments; and 38% (n = 58/154) responded for ≥75% of assessments. For >13 of 24 weeks, 47% of subjects achieved responses (Fig. 2). The median average daily dose for EPAG-exposed patients in Cohorts 1, 2, and 3 were 64.0 mg (0.93 mg/kg), 57.6 mg (1.50 mg/kg), and 37.0 mg (2.02 mg/kg), respectively. AEs Similar proportions of subjects in the EPAG and PBO groups reported an AE during the randomization period. The most common AEs (≥10% of subjects) were headache, upper respiratory tract infection, and nasopharyngitis in the EPAG group, and headache, epistaxis, and vomiting in the PBO group. Serious AEs (SAEs) were reported in 8% of EPAG subjects versus 12% of PBO subjects. No SAEs were reported by >1 subject in either treatment group except epistaxis, which was reported by 2 subjects in the PBO group. No SAEs were common to both treatment groups. In the randomized period, an ALT elevation of ³3 x ULN occurred in 5 (4.7%) subjects in the EPAG group and no subjects in the PBO group. In the OL period, there were an additional 7 subjects with ALT ³3 x ULN. All elevations resolved either while still on treatment or after discontinuation of study treatment. Overall, the hepatobiliary laboratory findings were mostly mild, reversible, and not accompanied by impaired liver function. Fewer EPAG than PBO subjects reported bleeding AEs (17% vs 36%, respectively). No thromboembolic events were reported. Cataract events were experienced by 2 subjects who received EPAG; both had used corticosteroids and 1 had pre-existing cataracts. Conclusions: EPAG was safe and raised platelet counts in 62% of pediatric patients with persistent and chronic ITP during the randomized phase. Treatment with EPAG was well tolerated in both studies as evidenced by the low incidence of treatment discontinuations due to AEs. Disclosures Bussel: Shionogi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Honoraria; Novartis: Honoraria; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; IgG of America: Research Funding; GlaxoSmithKline: Equity Ownership, Honoraria, Research Funding; Genzyme: Research Funding; Eisai, Inc.: Research Funding; Cangene: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Amgen: Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Symphogen: Membership on an entity's Board of Directors or advisory committees; Sysmex: Research Funding. Off Label Use: Eltrombopag is a thrombopoietin receptor agonist approved for the treatment of thrombocytopenia in adults with chronic ITP. Use in children and adolescents will be discussed.. Grainger:GlaxoSmithKline: Honoraria; Baxter: Honoraria, Research Funding; Amgen: Honoraria. Pongtanakul:GlaxoSmithKline: Research Funding. Komvilaisak:GlaxoSmithKline: I am an investigator on this study. Other. Sosothikul:CSL Behring: Research Funding; GlaxoSmithKline: Research Funding. Drelichman:GlaxoSmithKline: I am investigator on this study. Other. David:GlaxoSmithKline: Research Funding. Marcello:GlaxoSmithKline: Employment. Iyengar:GlaxoSmithKline: Employment. Chan:GlaxoSmithKline: Employment. Chagin:GlaxoSmithKline: Employment. Theodore:GlaxoSmithKline: Employment, Equity Ownership. Bakshi:GlaxoSmithKline: Employment, Equity Ownership. Bailey:GlaxoSmithKline: Employment, Equity Ownership.

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Non-Genotoxic Anti-CD117 Antibody Conditioning Results in Successful Hematopoietic Stem Cell Engraftment in Patients with Severe Combined Immunodeficiency

Blood ◽

10.1182/blood-2019-126239 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 800-800 ◽

Cited By ~ 2

Author(s):

Rajni Agarwal ◽

Christopher C. Dvorak ◽

Hye-Sook Kwon ◽

Janel R Long-Boyle ◽

Susan S Prohaska ◽

...

Keyword(s):

Monoclonal Antibody ◽

Stem Cell ◽

Board Of Directors ◽

Research Funding ◽

Severe Combined Immunodeficiency ◽

Combined Immunodeficiency ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Radio Therapy ◽

Equity Ownership

Successful hematopoietic cell transplantation (HCT) requires vacating recipient hematopoietic stem cell (HSC) niches to permit transplanted HSC to engraft. Currently, DNA damaging radiation or chemotherapy are used to eliminate recipient HSC and achieve niche clearance. We have pursued a non-genotoxic approach to target and deplete HSC using a humanized monoclonal antibody, AMG 191, that binds human CD117 (c-Kit), a receptor tyrosine kinase expressed on the surface of HSC and progenitor cells (HSPC). We have shown that AMG 191 suppresses human hematopoiesis in vitro, depletes human HSC in mice xenografted with human cells, and safely depletes HSC of non-human primates. We have initiated a Phase I dose escalation trial to test AMG 191 as the sole conditioning agent to achieve donor CD34-enriched HSPC engraftment in patients undergoing HCT for severe combined immunodeficiency (SCID) (ClinicalTrials.gov: NCT02963064). SCID is a severe genetic immune disorder curable only by HCT. Because of toxicity concerns, infants with SCID often receive donor hematopoietic grafts without conditioning, resulting in a lack of donor HSC engraftment. Instead, mature T lymphocytes and possibly lymphoid progenitors engraft but support only donor T cell development. This approach is associated with incomplete and poorly sustained immune reconstitution, and many patients have either no donor B cells and/or poor B cell function requiring life-long immunoglobulin replacement therapy. Second unconditioned donor HSC "boosts" can be performed, but they do not result in HSC engraftment and immune defects may persist. The primary endpoint of our study is to assess the safety and tolerability of AMG 191 as a conditioning agent in SCID patients. Secondary endpoints include AMG 191 pharmacokinetics (PK), host HSC depletion, and the determination of the dose of AMG 191 that achieves adequate donor HSC engraftment, defined as >5% donor blood granulocyte chimerism in peripheral blood at 24 weeks. Seven patients have been treated to date who are >12 weeks post-HCT (Table 1): three in each of the first two dose cohorts (0.1 and 0.3 mg/kg AMG 191), and one patient in the third cohort (1.0 mg/kg). An eighth patient has been treated at the 1.0 mg/kg dose and is three weeks post-HCT. Patients have a mixture of SCID genotypes. All patients treated to date had prior HCT with lack of donor HSC engraftment as evidenced by 0% donor sorted granulocyte chimerism at study entry. AMG 191 administration and infusion of original donor CD34+-selected cells were uniformly well tolerated. Pre- and post-infusion marrow analyses in five evaluable patients demonstrated dose-dependent decline in CD117+HSPC following AMG 191 treatment. Table 1 shows that four of six patients, who are >24 weeks post-HCT, reached the predefined endpoint of >5% granulocyte chimerism at 24 weeks, demonstrating donor HSC engraftment. The two patients who did not show donor engraftment at 24 weeks had detectable, low level (<5%) engraftment at later time points. All patients with follow up of >36 weeks show the production of recent thymic emigrants and/or de novo production of naïve T and/or B cells. In addition to improved lymphocyte values, patients have demonstrated clinical improvement including resolution of chronic diarrhea, significant weight gain, and reduced IVIG requirements. Conclusion: This study is the first demonstration of HSC engraftment following monoclonal antibody-based conditioning of patients without chemo(radio)therapy. Specifically, this first-in-human HCT trial shows that an anti-CD117 antibody safely clears HSC niches and facilitates donor HSPC engraftment in patients with SCID. Clinical benefit has been observed with minimal to no toxicity. Four of six evaluable patients have sustained evidence of donor myeloid engraftment along with T and B lymphopoiesis, indicative of engraftment of multipotent HSC. These results suggest that antibody conditioning for HCT may be preferable to traditional chemo(radio)therapy conditioning, especially in patients with non-malignant diseases and/or increased risk of toxicities due to such agents, such as certain forms of SCID, Fanconi anemia and sickle cell disease. Anti-CD117 antibody conditioning may also be applicable to gene therapy with genetically corrected autologous HSC. The AMG 191 study is actively enrolling previously transplanted SCID patients and newly diagnosed SCID patients. Disclosures Dvorak: Alexion Inc: Consultancy; Jazz Pharmaceuticals: Consultancy. Prohaska:Forty Seven Inc: Equity Ownership, Patents & Royalties. Weissman:Forty Seven Inc.: Consultancy, Equity Ownership, Patents & Royalties. Cowan:Rocket Pharma: Consultancy; Homology Medicine: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; California Institute Of Regenerative Medicine: Research Funding; UpToDate: Honoraria; Leadiant: Consultancy; NIH NIAD: Research Funding. Logan:Kadmon: Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite: Research Funding; TeneoBio: Consultancy; Novartis: Consultancy; Astellas: Research Funding; Abbvie: Consultancy; Incyte: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Kiadis: Consultancy; Jazz: Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees. Weinberg:U.S. Patent Office: Patents & Royalties: patent pending - submitted for aldehyde dehydrogenase 2 (ALDH2) activators to expand hematopoietic stem cells. Shizuru:Forty Seven Inc: Equity Ownership, Patents & Royalties.

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Targeting CXCR4, VLA4, and CXCR2 for Hematopoietic Stem Cell Mobilization

Blood ◽

10.1182/blood-2019-124373 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1916-1916

Author(s):

Daniel Cancilla ◽

Haresh Thakellapalli ◽

Marvin J Meyers ◽

Michael P. Rettig ◽

Ezhilarasi Chendamarai ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Hematopoietic Stem Cell ◽

Research Funding ◽

Patent Application ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Hematopoietic Stem Cell Mobilization ◽

Equity Ownership ◽

Cell Mobilization

Background: Hematopoietic stem cell (HSC) transplant is an essential treatment for a variety of blood disorders and malignancies. A key step in this procedure is the mobilization of donor stem cells. The most commonly used regimen for donor mobilization is a 5-day course of G-CSF. The length of this regimen coupled with the associated side effects emphasizes a need for superior alternatives. In recent years, there has been a growing understanding of mechanisms governing stem cell retention within the bone marrow niche. This has led to the development of new mobilization drugs that specifically target these processes. Two examples of previously described drugs that target mechanisms of stem cell retention are Plerixafor (a CXCR4 inhibitor already in clinical use), and truncated Gro-Beta (tGroβ; a CXCR2 agonist). Another potential target for inducing mobilization is disruption of the interaction between the VLA-4 integrin and its ligand VCAM-1. In this study, we evaluate the efficacy of novel VLA-4 inhibitors (VLA4i) alone and in combination with Plerixafor and/or tGroβ for the purposes of hematopoietic stem cell mobilization. Methods: We synthesized over 15 novel VLA-4 inhibitor molecules and tested their potency using soluble VCAM-1 binding assays. The 5 inhibitors determined to be most potent were then tested in vivo in DBA mice for their ability to mobilize HSCs alone and in combination with tGroβ and/or Plerixafor (n=5). HSC mobilization was measured in wild-type and splenectomized mice via flow cytometry to quantify the proportion of LSK (Lineage- Sca+ cKit+) cells as well as via Colony Forming Unit (CFU) assays. For competitive transplant, mobilized CD45.1+ BALB/c mouse blood (10 uL) was injected into lethally irradiated CD45.2+ BALB/c recipients alongside 2.5x105 CD45.2+ BALB/c bone marrow cells (n=10 / cohort). HSC engraftment was monitored monthly via flow cytometry for ratio of 45.1+ vs. 45.2+ cells in peripheral blood. Results: Firetagrast and BIO5192 are previously characterized VLA4i that have been administered to humans for indications unrelated to HSC mobilization. Our best VLA4i to date, LGB-2019, exhibited similar potency as BIO5192 in preventing the binding of sVCAM-1 to VLA-4 (IC50: 1.7nM) and was >200-fold more potent than firategrast. LGB-2019 showed increased aqueous solubility and mobilized 1.5-fold more murine LSK cells for a longer time period (peak HSC mobilization maintained for 4 hours) than BIO5192 when administered alone. Simultaneous injection of C57BL/6 mice with LGB-2019 (VLA4i), Plerixafor (CXCR4i) and tGro-β (CXCR2a) resulted in a synergistic increase in circulating CFUs (Fig. 1A; 9.8 x 103 CFUs/mL) and LSKs (Fig. 1B; 12.8 LSKs/uL) at 4 hours post-injection. In contrast, 5 days of G-CSF treatment mobilized approximately 3-fold and 8-fold less CFUs and LSKs, respectively (Fig. 1A-B). We saw no significant difference in mobilization for splenectomized vs. wildtype mice (23.4 x 103 CFUs/mL vs. 23.0 x 103 CFUs/mL) when mobilizing DBA/2 mice via VLA4i+CXCR4i+CXCR2a. Three months after competitive transplantation, blood obtained from BALB/c mice mobilized with the triple combination engrafted significantly better than blood obtained from mice treated with G-CSF or the dual combinations (Fig. 1C). Summary: New insights about the stem cell niche have allowed for the development of targeted drugs for the purposes of mobilization. Here, we show that a novel VLA-4 receptor inhibitor in combination with two other known mobilizers induces mobilization of hematopoietic stem and progenitor cells (CFU/LSK) at levels superior to the standard of care G-CSF and in a dramatically shortened time frame. Mouse transplant data also show superior engraftment in lethally irradiated recipients when using the triple cocktail regimen compared to the G-CSF mobilized graft. Secondary transplants are ongoing and will provide a more complete picture of primitive HSC mobilization and serial engraftment properties of the cells. Disclosures Rettig: WashU: Patents & Royalties: Patent Application 16/401,950. Karpova:WashU: Patents & Royalties: Patent Application 16/401,950. Ruminski:WahU: Patents & Royalties: Patent Application 16/401,950. Morrow:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. DiPersio:Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Equity Ownership; Incyte: Consultancy, Research Funding; Bioline Rx: Research Funding, Speakers Bureau; Macrogenics: Research Funding, Speakers Bureau; Karyopharm Therapeutics: Consultancy; Celgene: Consultancy; Amphivena Therapeutics: Consultancy, Research Funding; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; NeoImmune Tech: Research Funding.

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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 (<20 cells/μl) Peripheral Blood CD34+ Cell Count.

Blood ◽

10.1182/blood.v114.22.3230.3230 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3230-3230 ◽

Cited By ~ 1

Author(s):

Auayporn P. Nademanee ◽

Edward Stadtmauer ◽

Ivana N Micallef ◽

Patrick Stiff ◽

Sachin Marulkar ◽

...

Keyword(s):

Placebo Group ◽

Cell Count ◽

Board Of Directors ◽

Research Funding ◽

Fold Increase ◽

Advisory Committees ◽

Hematopoietic Stem ◽

Cell Counts ◽

Cd34 Cells ◽

Equity Ownership

Abstract Abstract 3230 Poster Board III-167 Background Pre-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. Methods Data 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). Results In 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. Conclusions These 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. Disclosures Nademanee: 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.

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