Evaluation of a Pan-Lysyl Oxidase Inhibitor, Pxs-5505, in Myelofibrosis: A Phase I, Randomized, Placebo Controlled Double Blind Study in Healthy Adults

BACKGROUND: Myeloproliferative neoplasms (MPNs) are clonal stem cell neoplasms characterized by terminal expansion of the myeloid cell lineage and include essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF). MF carries the worst prognosis and is characterized by reactive bone marrow fibrosis. Currently bone marrow transplant is the only known therapy that can reverse fibrosis and alter the disease course. Lysyl oxidases (LOX, LOXL1-4) are copper amine oxidase enzymes that facilitate the cross-linking of collagen and elastin through deamination and oxidization of lysine residues, yielding highly reactive aldehydes. This is essential for fibrotic tissue formation. An earlier study identified an important role for LOX in the development of MF in mice (Eliades et al, J. Biol. Chem. 2011; PMID: 21665949). Furthermore, small molecule pan-LOX inhibitors reduced spleen size and bone marrow fibrosis in mouse models of MF (Leiva et al, Int J. Hemat. 2019; PMID: 31637674). This provides clinical rationale for the use of pan-lysyl oxidase inhibition in MF. A Phase 1 study was conducted to establish the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PXS-5505, a pan-lysyl oxidase inhibitor. Plasma levels of LOX and LOXL2 were investigated in a separate cohort of MPN patients, with the ultimate goal to develop PXS-5505-based therapy in MF patients. METHODS: PXS-5505 was dosed orally in a Phase I, randomized, placebo-controlled, single ascending (Part A) and multiple ascending dose (Part B) double-blind study in healthy male volunteers. Plasma LOX and LOXL2 levels were also measured in a separate cohort of MPN patients using ELISA-based Single Molecule Array technology (Simoa; Quanterix). RESULTS: Forty subjects were enrolled in Part A and 16 were enrolled in Part B. In Part A, there were 5 cohorts consisting of 8 subjects (6 active, 2 placebo) with doses of 10, 50, 100, 200 or 300 mg administered once. In Part B, there were 2 cohorts of 8 subjects each (6 active, 2 placebo) at doses of 100 or 200 mg daily for 14 days. There were no significant treatment-related adverse events. Mean age in Part A was 32.0 years (SD 11.14) and 32.1 years (SD 12.14) in Part B. Cmax and AUC increased linearly across the dose range of 10 to 300 mg for single dose administration. In multiple dosing at 200 mg daily, Cmax was 916 ng/mL and AUC0-24 was 7421 hr*ng/mL on Day 14, with median Tmax of 1 hour and t1/2 of 7 hours. When measured in plasma, LOX was dose-dependently inhibited and achieved very strong inhibition (median 80%) with a 200 mg dose around Tmax. The 300 mg dosing did not significantly increase inhibition. Multiple daily doses of 100-200 mg resulted in 60-70% and 50-60% inhibition of plasma LOX at 12 and 24 hours. Average LOX plasma levels were 3.61 ng/mL (range: 3.20-13.42 ng/mL; SD: 2.92 ng/mL). We measured plasma LOX and LOXL2 levels in a separate MPN cohort of 9 ET, 8 PV, and 13 MF patients (mean age 61.4, range:24-84, 65% males). LOXL2 levels were higher in MF (mean 415 pg/mL) compared to ET (mean 209 pg/mL) and PV (mean 322 pg/ml), although this was not significant. However, LOXL2 levels in all MPN patients (mean 333 pg/mL) were significantly higher than LOXL2 levels in normal controls (mean 152 pg/mL, p<0.01). There were no significant differences in LOX levels in the two groups. DISCUSSION: PXS-5505 demonstrated an excellent safety profile and was well tolerated in healthy human subjects. PK/PD properties are consistent with preclinical data and support once or twice daily >100 mg dosing over 14 days. PXS-5505 achieves long-lasting, strong inhibition of lysyl oxidases. Plasma LOXL2 levels are higher in MF patients compared to healthy controls, and we found no significant disease associations of LOX or LOXL2 among MPN subtypes in our small cohort. LOXL2 is likely a more sensitive MF biomarker as it is present at low concentrations in the blood, while LOX is constantly produced from major organs making detection due to disease more difficult. Based on previous mouse studies, it is possible that LOX levels would be higher in MF patients when compared to age-matched controls, which we will investigate further. We will open a Phase IB/II study of PXS-5505 in MF patients resistant to ruxolitinib. Disclosures Neuberg: Madrigak Pharmaceuticals: Current equity holder in publicly-traded company; Celgene: Research Funding; Pharmacyclics: Research Funding. Ravid:Pharmaxis: Research Funding. Jarolimek:Pharmaxis Ltd: Current Employment. Charlton:Pharmaxis Ltd: Current Employment. Hobbs:Novartis: Honoraria; Constellation: Honoraria, Research Funding; Jazz: Honoraria; Celgene/BMS: Honoraria; Merck: Research Funding; Incyte: Research Funding; Bayer: Research Funding.

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Efficacy, Safety, and Confirmation of the Recommended Phase 2 Dose of Ruxolitinib Plus Panobinostat in Patients with Intermediate or High-Risk Myelofibrosis

Blood ◽

10.1182/blood.v124.21.711.711 ◽

2014 ◽

Vol 124 (21) ◽

pp. 711-711 ◽

Cited By ~ 6

Author(s):

Jean-Jacques Kiladjian ◽

Florian H Heidel ◽

Alessandro M. Vannucchi ◽

Vincent Ribrag ◽

Francesco Passamonti ◽

...

Keyword(s):

Bone Marrow ◽

High Risk ◽

Board Of Directors ◽

Research Funding ◽

Phase Iii ◽

Spleen Volume ◽

Bone Marrow Fibrosis ◽

Advisory Committees ◽

Expansion Phase ◽

Marrow Fibrosis

Abstract Background: Myelofibrosis (MF) is a clonal neoplastic disease resulting in bone marrow fibrosis, splenomegaly, and debilitating constitutional symptoms. The Janus kinase (JAK) pathway is often dysregulated in MF, and agents targeting this pathway have demonstrated efficacy in this disease. Ruxolitinib (RUX), a potent JAK1/JAK2 inhibitor, demonstrated superiority in spleen volume reduction, symptom improvement, and survival compared with the control arm in the phase III COMFORT-I and COMFORT-II studies. Panobinostat (PAN), a potent pan-deacetylase inhibitor (pan-DACi), inhibits JAK signaling through disruption of the interaction of JAK2 with the protein chaperone heat shock protein 90. In phase I/II studies, PAN has shown splenomegaly reduction and improvement of bone marrow fibrosis. The combination of RUX and PAN demonstrated synergistic anti-MF activity in preclinical studies. These preliminary results led to the initiation of a phase Ib study evaluating the combination of RUX and PAN in patients (pts) with MF. The updated results from the expansion phase of this trial are presented here. Methods: Eligible pts had intermediate-1, -2, or high-risk primary MF, post-polycythemia vera MF, or post-essential thrombocythemia MF by International Prognostic Scoring System criteria, with palpable splenomegaly (≥ 5 cm below the costal margin). The primary objective was determination of the maximum tolerated dose (MTD) and/or recommended phase II dose (RPIID). Secondary objectives included safety, efficacy, and pharmacokinetics. Exploratory endpoints included assessment of improvement in bone marrow fibrosis and reduction of JAK2 V617F allele burden. The treatment schedule was RUX (5-15 mg) twice daily (bid) every day and PAN (10-25 mg) once daily 3 times per week (tiw; days 2, 4, and 6) every other week (qow) in a 28-day cycle. Following dose escalation and identification of the potential RPIID, additional pts were enrolled into the expansion phase and treated at this dose. Results: As of March 14, 2014, a total of 61 pts were enrolled (38 escalation phase and 23 expansion phase). The median duration of exposure to PAN and to RUX was 24.6 weeks and 24.0 weeks, respectively, for pts treated in the expansion phase. Three DLTs were observed in the escalation phase (grade 4 thrombocytopenia [n = 2], grade 3 nausea [n = 1]). No MTD was reached. The RPIID was confirmed to be RUX 15 mg bid and PAN 25 mg tiw qow in May 2014. Among the 34 pts treated at the RPIID, grade 3/4 adverse events (AEs) regardless of causality included anemia (32%), thrombocytopenia (24%), diarrhea (12%), asthenia (9%), and fatigue (9%). AEs led to discontinuation in 6% of pts treated at the RPIID. Two pts treated at the RPIID died due to causes unrelated to study treatment (1 due to myocardial infarction and 1 due to progression of myelofibrosis). Among the pts treated at the RPIID, 79% showed a >50% decrease in palpable spleen length, with 100% decrease (non-palpable spleen) being observed in 53% of pts. Additionally, 48% of pts treated at the RPIID in the expansion phase achieved ≥35% reduction in spleen volume (Figure). These results are similar to those observed for spleen volume response at 24 weeks among pts who received single-agent RUX on the phase III COMFORT-I (41.9%) and COMFORT-II (32%) studies. Conclusions: The combination of the JAK1/JAK2 inhibitor RUX and the pan-DACi PAN was well tolerated and resulted in high rates of reductions in splenomegaly in pts with intermediate- and high-risk MF. Although a relatively larger proportion of patients experienced spleen volume reductions at week 24 as compared to the COMFORT studies, the smaller sample size, shorter follow up times and potential differences in the patient populations preclude definitive comparisons. Similar to COMFORT-I and II trials, hematological AEs, specifically anemia and thrombocytopenia, were the most common AEs observed in pts treated with the combination therapy. Pts continue to be treated in the expansion phase at the RPIID. Updated safety, efficacy, and exploratory analyses on bone marrow fibrosis, JAK V617F allele burden, and biomarkers, including cytokines, will be presented. Figure Change in Spleen Volume in Expansion Phase Figure. Change in Spleen Volume in Expansion Phase Disclosures Kiladjian: Novartis: Honoraria, Research Funding, Speakers Bureau; Shire: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Honoraria, Research Funding. Heidel:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Ribrag:Celgene: Consultancy; Pharmamar: Consultancy; Epizyme: Research Funding; Bayer: Consultancy, Research Funding; Servier: Consultancy, Honoraria, Research Funding. Conneally:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kindler:Novartis: Consultancy. Acharyya:Novartis: Employment. Gopalakrishna:Novartis: Employment. Ide:Novartis: Employment, Equity Ownership. Loechner:Novartis: Employment. Mu:Novartis: Employment. Harrison:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria; CTI: Consultancy, Honoraria; Gilead: Honoraria; SBio: Consultancy; Shire: Speakers Bureau.

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Efficacy and Safety of Eltrombopag for Treatment of Patients with Myelodysplastic Syndromes after Hypomethylating-Agent Failure: A Phase 2 Clinical Trial

Blood ◽

10.1182/blood.v126.23.1691.1691 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1691-1691 ◽

Cited By ~ 2

Author(s):

Maliha Khan ◽

Bodden Kristy ◽

Tapan Kadia ◽

Alessandra Ferrajoli ◽

Yesid Alvarado ◽

...

Keyword(s):

Clinical Trial ◽

Bone Marrow ◽

Myelodysplastic Syndromes ◽

Research Funding ◽

Phase 2 ◽

Open Label ◽

Bone Marrow Fibrosis ◽

First Response ◽

Transfusion Requirements ◽

Marrow Fibrosis

Abstract Background: Myelodysplastic syndromes (MDS) are malignant clinical disorders characterized by ineffective hematopoiesis, bone marrow dysplasia, peripheral cytopenias and a property to transform into acute myeloid leukemia (AML). Standard of care for MDS includes the hypomethylating agents (HMAs) (i.e. azacitidine, decitabine) to improve quality of life, decrease transfusion requirements and improve clinical outcome. However not all patients (pts) respond to HMAs and even in responding pts, cytopenias may persist. HMA-failure MDS has extremely poor prognosis and currently there are no approved therapeutic options for such pts who are often of advanced age with frequent comorbidities. Objectives: The dual primary objectives of this study evaluate the safety and efficacy of the second-generation thrombopoietin-receptor agonist (TPO-RA) eltrombopag (EPAG) for the treatment of MDS pts at the time of HMA-failure. Secondary objectives include incidence of transformation to AML and evaluation of bone marrow fibrosis during therapy. Methods: Eligible pts for this 2-arm phase 2 open-label clinical trial included adults with MDS after completing >4 HMA cycles with failure to achieve at least a partial response, or the presence of ongoing cytopenias per IWG criteria. Arm A includes eltrombopag monotherapy and Arm B includes eltrombopag with continuation of the HMA at the previous dosing schedule. The starting eltrombopag dose is 200mg orally daily, which can be increased to 300mg in the absence of toxicity. First response is assessed after 2 cycles with each cycle lasting 28 days. The primary efficacy endpoint was overall response rate based on the IWG-2006 criteria. Results: To date, 23 pts with a median age of 72 years (range 42-84 years) have been enrolled. Prior to study entry, pts had received a median of 6 (range 4-25) HMA cycles. Cytogenetics were diploid in 12 (53%), intermediate in 7 (30%), and high risk in 4 (17%) pts by IPSS. Median bone marrow blasts at study start was 3% (range 0-15%). Arm A has enrolled 7 pts with a median age of 74 years; Arm B has enrolled 16 pts with median age of 69 years. In Arm B, ongoing HMA therapy includes azacitidine in 7 (44%) and decitabine in 9 (56%). Nine (39%) pts increased to 300mg EPAG after median of 8 weeks on study. Median total cycles received on study is 5 (1-17); median OS has not been reached. Overall, 16 pts are response-evaluable; 7 pts discontinued prior to the first response assessment at 2 months (4 due to AEs including myalgias/fatigue (n=2), hyperbilirubinemia (n=1), and pneumonia (n=1), 2 per pt request and 1 for pt inability to comply with protocol requirements). Of the 16 response-evaluable pts, 3 (19%) in Arm B demonstrated platelet improvement, including one pt necessitating EPAG dose-reduction to 100mg due to platelet count exceeding 450 x10⁹/L with concomitant ANC recovery at 200mg EPAG dose level. An additional 8 (35%) pts have remained on study for a median of 5 cycles (2-17) with stable disease. Two pts discontinued therapy due to disease progression, including 1 (4%) that progressed to AML. The most common non-hematologic AEs regardless of attribution included hyperbilirubinemia (n=14, 61%), fatigue (n=13, 56%) myalgias (n=11, 48%), fever (7, 30%), dyspnea (7, 30%), nausea (6, 26%) and transaminitis (4, 17%). No significant increase in bone marrow fibrosis has been observed. Conclusion: Eltrombopag orally daily appears to be a safe and beneficial supportive adjunct for pts with MDS while receiving HMA-therapy or after HMA-failure due to persistent cytopenias. Treatment on this study continues and larger prospective clinical trials are needed to confirm these preliminary findings. Disclosures Off Label Use: Eltrombopag for the treatment of MDS-related cytopenias". Pemmaraju:Stemline: Research Funding; Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; LFB: Consultancy, Honoraria. Konopleva:Novartis: Research Funding; AbbVie: Research Funding; Stemline: Research Funding; Calithera: Research Funding; Threshold: Research Funding. DiNardo:Novartis: Research Funding.

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A Phase 2 Study to Evaluate the Efficacy and Safety of Simtuzumab in Adult Subjects with Primary, Post Polycythemia Vera (PV) or Post Essential Thrombocythemia (ET) Myelofibrosis

Blood ◽

10.1182/blood.v126.23.2810.2810 ◽

2015 ◽

Vol 126 (23) ◽

pp. 2810-2810

Author(s):

Srdan Verstovsek ◽

Michael R. Savona ◽

Ruben A. Mesa ◽

Stephen Oh ◽

Hua Dong ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Research Funding ◽

Phase 2 ◽

Fibrosis Score ◽

Bone Marrow Fibrosis ◽

Advisory Committees ◽

Equity Ownership ◽

Stage 1 ◽

Marrow Fibrosis

Abstract Background: Simtuzumab (SIM) is a humanized monoclonal antibody that inhibits lysyl oxidase-like molecule 2 (LOXL2), an extracellular matrix enzyme that catalyzes the covalent cross-linking of collagen and is widely expressed across many fibrotic diseases. In pre-clinical models, inhibition of LOXL2 blocks fibroblast activation, which plays an important role in the development of organ fibrosis. In Phase 1 studies, SIM was well-tolerated in patients (pts) with advanced solid tumors, liver fibrosis, and idiopathic pulmonary fibrosis (IPF). A Phase 2, open-label study to determine the efficacy of SIM alone (Stage 1) and combined with ruxolitinib (rux) (Stage 2) in pts with primary myelofibrosis (PMF) and post-ET/PV MF was initiated. Methods: Eligible pts had intermediate-1, intermediate-2, or high risk disease and Eastern Cooperative Oncology Group performance status of <2. The primary endpoint was rate of clinical response as defined by a reduction in bone marrow fibrosis score following 24 weeks of treatment with SIM. Patients were randomized in a 1:1 ratio to receive 200 mg or 700 mg SIM by intravenous infusion every 2 weeks as monotherapy (Stage 1, n=24) or combined with rux (Stage 2, n=30). Patients received SIM for up to 24 weeks. Bone marrow biopsies and aspirates were performed approximately every 3 months. Bone marrow fibrosis scoring was performed and quantified at local investigator sites using the European Consensus on Grading Bone Marrow Fibrosis. Myelofibrosis symptoms were evaluated using the Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) and changes in hematologic parameters and splenomegaly were assessed. Results: Between 7/14/11 and 9/22/14, 54 pts were randomized and treated (200 mg SIM [n=12], 700 mg SIM [n=12], 200 mg SIM/rux [n=15], and 700 mg SIM/rux [n=15]). In Stage 1, 0 subjects (0%) in the SIM 200 mg group and 2 subjects (16.7%; 90% CI 3.0%, 43.8%) in the SIM 700 mg group showed a reduction in bone marrow fibrosis score from Baseline to Week 24. In Stage 2, 1 subject (6.7%; 90% CI 0.3%, 27.9%) in the SIM 200 mg/rux group and 2 subjects (13.3%, 90% CI 2.4%, 36.3%) in the SIM 700 mg/rux group showed a reduction in bone marrow fibrosis score from Baseline to Week 24. In an exploratory analysis, similar numbers of subjects showed increases in bone marrow fibrosis scores. SIM treatment was not associated with meaningful improvements in hematologic parameters or reductions in MPN-SAF score or spleen size. The most frequent adverse events were those commonly associated with MF, including constitutional symptoms and reductions in hematological parameters. Conclusions: SIM treatment alone or in combination with rux is safe but does not reliably reduce bone marrow fibrosis in pts with MF. The reason for reduction of marrow fibrosis in some patients and increase in others is unclear and may be sampling variability. Clinical studies of SIM in IPF and liver fibrosis are ongoing. Disclosures Savona: Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Research Funding; Astex Pharmaceuticals, Inc: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Mesa:Incyte Corporation: Research Funding; CTI Biopharma: Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; Pfizer: Research Funding; Promedior: Research Funding; Genentech: Research Funding; NS Pharma: Research Funding; Gilead: Research Funding. Oh:CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees. Dong:Gilead Sciences: Consultancy, Equity Ownership. Thai:Gilead Sciences: Employment, Equity Ownership. Gotlib:Allakos, Inc.: Consultancy.

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A Phase 3, Double-Blind, Placebo-Controlled, Randomized Study Evaluating Navitoclax in Combination with Ruxolitinib in Patients with Myelofibrosis (TRANSFORM-1)

Blood ◽

10.1182/blood-2020-139758 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 4-4

Author(s):

Jalaja Potluri ◽

Jason Harb ◽

Abdullah A. Masud ◽

Jessica E. Hutti

Keyword(s):

Bone Marrow ◽

Platelet Count ◽

Stock Options ◽

Myeloproliferative Neoplasm ◽

Bone Marrow Fibrosis ◽

Double Blind ◽

Starting Dose ◽

Secondary Endpoints ◽

Marrow Fibrosis

Background: Myelofibrosis (MF) is a rare myeloproliferative neoplasm with poor clinical outcomes. It is characterized by bone marrow fibrosis and an array of constitutional symptoms that impair quality of life. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only potential curative therapy for MF, but HSCT is only accessible to a minority of patients and is associated with high morbidity and high rates of transplant-related mortality. JAK inhibitors (JAKi), including the JAK1/2i ruxolitinib and JAK2i fedratinib, are approved for the treatment of primary and secondary MF based on reduction in splenomegaly and disease-related symptoms; however, they have little impact on bone marrow fibrosis and are not effective at managing all clinical manifestations of MF. Therefore, a substantial clinical need for novel therapies to improve the disease course of MF exists. Navitoclax is an oral, potent, small-molecule inhibitor of the antiapoptotic B-cell lymphoma 2 (BCL-2) family proteins BCL-XL, BCL-2, and BCL-w and has demonstrated cell-killing activity in myeloproliferative neoplasm-derived cell lines and primary specimens ex vivo. Preliminary data from a Phase 2 study (NCT03222609) of ruxolitinib-experienced patients with primary or secondary MF have shown favorable spleen responses and tolerability with navitoclax plus ruxolitinib (Harrison et al. EHA 2020. EP1081). TRANSFORM-1 aims to evaluate the combination of navitoclax and ruxolitinib vs placebo and ruxolitinib in adults with primary or secondary MF who have not previously received a JAK2i. Study Design and Methods: In this Phase 3, double-blind, placebo-controlled study (NCT04472598), patients aged ≥18 years with intermediate-2 or high-risk MF with measurable splenomegaly, evidence of MF-related symptoms, no prior treatment with JAK2i, and Eastern Cooperative Oncology Group Performance Score ≤2 will be eligible for enrollment. Candidates for allo-HSCT and those who have received prior treatment with a BH3-mimetic compound or BET inhibitor will be excluded. Patients will be enrolled across 130 sites in approximately 17 countries. Planned target enrollment is 230 patients. Patients will be randomized 1:1 to receive navitoclax or placebo, plus ruxolitinib. Randomization stratification factors include intermediate-2 vs high-risk MF and platelet count ≤200 × 109/L vs >200 × 109/L. Navitoclax will be administered orally at a starting dose of 200 mg (platelet count >150 × 109/L) or 100 mg escalated to 200 mg once daily if tolerated after ≥7 days (platelet count ≤150 × 109/L). Ruxolitinib will be administered orally at a starting dose of 20 mg (platelet count >200 × 109/L) or 15 mg (platelet count 100-200 × 109/L) twice daily. Treatment may continue until the end of clinical benefit, unacceptable toxicity, or discontinuation criteria have been met. Patients who discontinue without progression will enter post-treatment follow-up; after disease progression or initiation of post-treatment cancer therapy, patients will enter survival follow-up. The primary endpoint of the study is ≥35% reduction in spleen volume from baseline (SVR35) at Week 24, as measured by magnetic resonance imaging or computed tomography, per International Working Group (IWG) criteria. Secondary endpoints include ≥50% reduction in total symptom score from baseline at Week 24 (measured by Myelofibrosis Symptom Assessment Form v4.0), duration of SVR35, change in fatigue from baseline, time to deterioration of physical functioning, anemia response per IWG criteria, SVR35 per IWG, reduction in grade of bone marrow fibrosis from baseline, overall survival, leukemia-free survival, and overall response and composite response per IWG criteria. Exploratory endpoints include progression-free survival. Safety will be assessed throughout the study via adverse event (AE) monitoring, physical examinations, vital sign measurements, electrocardiogram variables, and clinical laboratory testing. AEs will be graded per National Cancer Institute Common Terminology Criteria for AEs v5.0. The primary statistical analysis will be conducted using a stratified Cochran-Mantel-Haenszel test, and time-to-event secondary endpoints will be analyzed using a stratified log-rank test and Kaplan-Meier methodology. Hazard ratios will be estimated using stratified Cox proportional hazards model. Disclosures Potluri: AbbVie: Current Employment, Other: may hold stock or stock options. Harb:AbbVie: Current Employment, Other: may hold stock or stock options. Masud:AbbVie: Current Employment, Other: may hold stock or stock options . Hutti:AbbVie Inc.: Current Employment, Other: may hold stock or stock options. OffLabel Disclosure: Navitoclax is an investigational drug for the treatment of myelofibrosis

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Control of Megakaryocyte Expansion and Bone Marrow Fibrosis by Lysyl Oxidase

Journal of Biological Chemistry ◽

10.1074/jbc.m111.243113 ◽

2011 ◽

Vol 286 (31) ◽

pp. 27630-27638 ◽

Cited By ~ 49

Author(s):

Alexia Eliades ◽

Nikolaos Papadantonakis ◽

Ajoy Bhupatiraju ◽

Kelley A. Burridge ◽

Hillary A. Johnston-Cox ◽

...

Keyword(s):

Bone Marrow ◽

Lysyl Oxidase ◽

Bone Marrow Fibrosis ◽

Marrow Fibrosis

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Genomic Characterization Provides Diagnostic Clarity in Cases with Overlapping Bone Marrow Fibrosis and Monocytosis

Blood ◽

10.1182/blood-2018-99-117796 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4283-4283

Author(s):

Andrew T Kuykendall ◽

Chetasi Talati ◽

Ling Zhang ◽

Najla Al Ali ◽

Kendra L. Sweet ◽

...

Keyword(s):

Bone Marrow ◽

Research Funding ◽

Monocyte Count ◽

Bone Marrow Fibrosis ◽

Genomic Features ◽

Prognostic Features ◽

Pathologic Features ◽

Trisomy 9 ◽

Disease Specific ◽

Marrow Fibrosis

Abstract Introduction: Chronic myelomonocytic leukemia (CMML) and primary myelofibrosis (MF) are distinct myeloid malignancies with clinical and pathologic features that often overlap. The presence of significant bone marrow fibrosis with concomitant monocytosis can be diagnostically challenging. Distinguishing between these two clinical entities has important prognostic and therapeutic implications. In this study, we aimed to genomically characterize cases with overlapping features of both fibrosis and monocytosis and describe their clinical outcomes. Then, using well-established CMML and MF databases, we aimed to identify disease-specific genomic abnormalities to allow for improved diagnostic characterization. Methods: Including molecularly annotated patients (pts) from our CMML and MF databases, we created 3 cohorts. Cohort 1 was comprised of MF pts without significant monocytosis. Cohort 2 included CMML pts with absent/minimal bone marrow fibrosis. Cohort 3 included CMML pts with fibrosis and MF pts with monocytosis. Significant fibrosis defined as grade 2-3 by European consensus recommendations. Monocytosis defined as an absolute (>800/µL, the upper limit of normal in our laboratory) and relative (>10%) peripheral monocyte count. Cohorts 1 and 2 were compared to establish disease-specific somatic gene mutation patterns. Enriched variables were those that occurred significantly more often with p < 0.05. Specificity threshold of > 95% was used. Blinded pathological review of overlap bone marrow cases revealed concordance with original diagnosis in > 95% of cases. Results: Cohorts 1, 2 and 3 were comprised of 181, 168 and 61 pts, respectively. Among 61 pts in cohort 3, 26 had a prior CMML diagnosis and 35 had prior MF diagnosis. Median OS (mOS) in cohort 1 was 161 months (mo) compared to 35 mo in cohort 2 (p < 0.001) and 42 mo in cohort 3 (p < 0.001). mLFS for cohorts 1, 2, and 3 were not reached, 61 mo and 42 mo, respectively (p < 0.001). We compared molecular and cytogenetic abnormalities between cohort 1 and 2, assessing individual and commonly co-occurring abnormalities. Genomic abnormalities more common in CMML were mutations in TET2 (p < 0.001), RAS (p < 0.001), RUNX1 (p < 0.001), SRSF2 (p < 0.001), CBL (p = 0.05), ASXL1 (p = 0.04), TET2/SRSF2 (p < 0.001), TET2/ASXL1 (p < 0.001), TET2/RUNX1 (p = 0.03), SRSF2/ASXL1 (p = 0.004), and normal karyotype (p = 0.002). Genomic abnormalities more common in MF included driver mutations (i.e. JAK2, MPL, or CALR) (p < 0.001), del 20q (p = 0.03), del 13q (p < 0.001), and trisomy 9 (p = 0.004). Disease-specific abnormalities were those that were enriched in either CMML or MF with a specificity of >95%. CMML-specific abnormalities included RAS mutations and co-mutations in TET2/RUNX1, TET2/SRSF2, and SRSF2/ASXL1. MF-specific genomic abnormalities included del20q, del13q, and trisomy 9. We applied these disease-specific genomic abnormalities to cohort 3 to see if these findings could stratify pts toward a CMML-like genotype or MF-like genotype. Of 61 patients, 29 displayed only CMML-like genomic features (genomic CMML), 7 only MF-like features (genomic MF), 4 had both CMML and MF-specific features (genomic overlap) and 21 genomically undefined. Among those in cohort 3 with clinical MF diagnosis, 16 (46%) were reclassified as genomic CMML, 6 (17%) as genomic MF, 3 (9%) as genomic overlap, and 10 (31%) as genomically undefined. Among those with an original clinical diagnosis of CMML, 1 was redefined as genomic MF. OS for genomic CMML did not differ from genomic MF (p = 0.70). There was a trend for inferior LFS in genomic CMML compared to genomic MF (40 mo vs 59 mo, p = 0.19). Multivariate analysis identified the strongest prognostic features in cohort 3 as age > 70 (OR 9.4, p = 0.05), platelet count < 100,000/µL (OR 4.6, p = 0.02) and degree of bone marrow fibrosis (OR 5.1, p = 0.009). Conclusions: Specific genomic features distinguish CMML from MF. Application of these findings to pts with overlapping clinicopathologic features provides clarity in >50% of cases, primarily reclassifying patients as CMML. Clinically, outcomes in this overlap group with bone marrow fibrosis and monocytosis mirror those of CMML, regardless of genomic assignment; however, the presence of thrombocytopenia and magnitude of bone marrow fibrosis provide further prognostic discrimination. Future studies testing CMML-like therapeutic strategies should be considered in MF with monocytosis. Disclosures Kuykendall: Celgene: Honoraria; Janssen: Consultancy. Sweet:BMS: Honoraria; Celgene: Honoraria, Speakers Bureau; Jazz: Speakers Bureau; Astellas: Consultancy; Phizer: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; Agios: Consultancy; Jazz: Speakers Bureau; Agios: Consultancy; Phizer: Consultancy; Astellas: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; BMS: Honoraria; Celgene: Honoraria, Speakers Bureau. Sallman:Celgene: Research Funding, Speakers Bureau. List:Celgene: Research Funding. Komrokji:Novartis: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau.

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Trial in Progress: Phase Ib/II Study of Bcl-2/Bcl-Xl Inhibitor Pelcitoclax (APG-1252) in Patients with Myelofibrosis (MF) That Progressed after Initial Therapy

Blood ◽

10.1182/blood-2020-137260 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 15-16

Author(s):

Naveen Pemmaraju ◽

Boyd Mudenda ◽

Cunlin Wang ◽

Jiao JI ◽

Ming Lu ◽

...

Keyword(s):

Bone Marrow ◽

Clinical Benefit ◽

Research Funding ◽

Publicly Traded ◽

Bone Marrow Fibrosis ◽

Dual Inhibitor ◽

Jak2 Inhibitor ◽

Grant Support ◽

Marrow Fibrosis ◽

Jak2 Inhibitors

Background: Pelcitoclax (APG-1252), a novel dual inhibitor of Bcl-2/Bcl-xL, is active as monotherapy in patients with advanced solid tumors and well tolerated up to 240 mg twice weekly (NCT03387332). Preclinical data suggest that cells with Janus-associated kinase-2 (JAK2) mutations, including those associated with bone marrow fibrosis, are dependent on Bcl-2/Bcl-xL for survival and that addition of BH3 mimetics targeting Bcl-2/Bcl-xL induces apoptosis. Furthermore, in JAK2‒mutated cell models, apoptotic synergy is demonstrated when a JAK2 inhibitor and Bcl-2/Bcl-xL inhibitor are combined, as inhibition of Bcl-xL overcomes resistance to JAK2 inhibitors. Taken together, APG-1252 could overcome resistance to JAK2 inhibitors, and the combination could augment clinical benefit in patients with suboptimal responses to JAK2 inhibitor‒based therapy. Study Objectives: The primary objective of this open-label trial is to evaluate the safety and efficacy of APG-1252, as monotherapy and when combined with ruxolitinib, in adults with histologically or cytologically confirmed MF who require therapy and are ineligible for JAK2 inhibitors (and can receive single-agent APG-1252) or have had inadequate responses to ruxolitinib-based therapy (and can receive this treatment plus APG-1252). Secondary objectives include APG-1252 pharmacokinetics, time to response, and duration of response. Exploratory objectives include changes in cytogenetics and molecular mutations, bone marrow fibrosis, and cytokines on treatment. Study Design: The study is divided into Part 1 (APG-1252 monotherapy) and Part 2 (APG-1252 plus ruxolitinib). For Part 1, the key inclusion criterion is ineligibility for JAK2 inhibitors and for Part 2, inadequate responses to prior ruxolitinib-based therapy. A standard 3+3 dose-escalation design is being implemented to determine the maximum tolerated dose (MTD) of APG-1252 monotherapy in Part 1 and APG-1252 combined with ruxolitinib in Part 2. APG-1252 will initially be administered at 160 mg intravenously by 30-minute injection once weekly in a 28-day cycle. The dose can be escalated to a maximum of 240 mg or reduced to a minimum of 80 mg, depending on tolerability. Part 2 will begin once the MTD and recommended phase 2 dose (RP2D) of APG-1252 monotherapy have been determined. In Part 2, ruxolitinib will be administered orally twice daily per the package insert. After the MTD for APG-1252 monotherapy has been determined, no additional patients will be enrolled in Part 1; however, up to 15 to 30 additional patients can be enrolled in Part 2, to further evaluate the safety and anticancer activity of the combination at MTD or RP2D. Patients will continue treatment until disease progression or unacceptable toxicity. Clinical responses are being assessed every 12 weeks according to criteria from the International Working Group‒Myeloproliferative Neoplasms Research and Treatment and European LeukemiaNet panels, while optimal clinical benefit will be evaluated at 24 weeks. Enrollment will be from September 2020 and preliminary results estimated in October 2022. For further information, contact: [email protected]. Registration: ClinicalTrials.gov Identifier NCT04354727. Disclosures Pemmaraju: Pacylex Pharmaceuticals: Consultancy; Roche Diagnostics: Honoraria; LFB Biotechnologies: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Celgene: Honoraria; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria; Affymetrix: Other: Grant Support, Research Funding; Cellectis: Research Funding; Daiichi Sankyo: Research Funding; Plexxikon: Research Funding; Samus Therapeutics: Research Funding; DAVA Oncology: Honoraria; Blueprint Medicines: Honoraria; Novartis: Honoraria, Research Funding; Incyte Corporation: Honoraria; SagerStrong Foundation: Other: Grant Support. Mudenda:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Wang:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. JI:Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company. Lu:Ascentage Pharma Group: Current Employment, Current equity holder in publicly-traded company. Fu:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Liang:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. McClain:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Sheladia:Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Verstovsek:Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Blueprint Medicines Corp: Research Funding; PharmaEssentia: Research Funding; ItalPharma: Research Funding; AstraZeneca: Research Funding; Protagonist Therapeutics: Research Funding; Promedior: Research Funding; Celgene: Consultancy, Research Funding; NS Pharma: Research Funding; Genentech: Research Funding; CTI Biopharma Corp: Research Funding; Incyte Corporation: Consultancy, Research Funding; Roche: Research Funding; Gilead: Research Funding. Yang:Ascentage Pharma (SuZhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests. Zhai:Ascentage Pharma (SuZhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests.

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Transcriptional Landscape of the Microenvironment in Bone Marrow Fibrosis at Single Cell Level

Blood ◽

10.1182/blood-2019-126897 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1675-1675

Author(s):

Nils B. Leimkühler ◽

Ronghui Li ◽

Helene Gleitz ◽

Inge Snoeren ◽

Stijn Fuchs ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Research Funding ◽

Cell Level ◽

Bone Marrow Fibrosis ◽

Advisory Committees ◽

Molecular Alterations ◽

Ecm Proteins ◽

Travel Grant ◽

Marrow Fibrosis

Although the molecular alterations in hematopoietic cells which drive the development of myeloproliferative neoplasms (MPN) have been largely defined, reactive cellular alterations in the non-hematopoietic compartment remain rather obscure and have not been studied at single cell level. We therefore profiled enriched non-hematopoietic bone marrow cells by scRNAseq in bone marrow (BM) fibrosis compared to healthy marrow. BM fibrosis was induced by transplantation of hematopoietic stem and progenitor cells (HSPCs) with overexpression of Thrombopoietin (ThPO) into lethally irradiated mice. As ThPO-overexpression robustly leads to reticulin fibrosis in all mice (100%), we were able to study 1) pre-fibrosis (5 weeks after transplantation; reticulin fibrosis grade 0) and 2) manifest bone marrow fibrosis (10 weeks after transplantation, reticulin grade 2-3). The analysis revealed a total of 8 distinct clusters: 1-4) subpopulations of mesenchymal stromal cells (MSC-1: adipogenic, MSC-2: osteogenic, MSC-3: transition, MSC-4: interferonhigh), 5) osteoblastic lineage cells (OLCs), 6) arterial endothelial cells (ECs) and 7-8) Schwann cell precursors (SCP-1: non-myelinating SCPs; SCP-2: myelinating SCPs). Exposure to ThPO overexpressing HSPCs resulted in an overrepresentation of adipogenic MSCs at the expense of all other MSC subclusters. Differential gene expression analysis revealed a functional reprogramming of the "adipogenic" expanding MSCs with down-regulation of hematopoiesis-support and induction of a secretory phenotype including upregulation of various extracellular matrix (ECM) proteins driving fibrosis. Interestingly, only two MSC subclusters gained significant ECM expression indicating myofibroblast differentiation. Expansion of OLCs in BM fibrosis suggested a differentiation of the underrepresented MSC subpopulations into osteolineage cells which was confirmed by pseudotime analysis. Myelinating SCPs, highly expressing interleukin-33 (IL-33), showed the largest expansion in fibrosis. IL-33 is described to play a significant role in solid organ fibrosis by having both pro- and anti-fibrotic effects. Nerve injury triggers the expansion of myelinating and non-myelinating Schwann cells to promote repair, suggesting that mSCPs increase as compensatory and regenerative mechanism for the previously described MPN-induced sympathetic neuropathy. Dissection of cellular and molecular alterations in pre-fibrosis and manifest fibrosis demonstrated that only one MSC subpopulation was already significantly expanded in the pre-fibrotic phase, but only showed minor transcriptional changes. The upregulation of ECM proteins, osteogenesis as well as proinflammatory genes were hallmark features of manifest fibrosis. Interestingly, the overrepresentation of IL-33 expressing mSCPs was more pronounced in the pre-fibrotic phase, indicating that the expansion is a regenerative phenomenon failing in the stages of manifest fibrosis. Our findings were validated in the clinically relevant JAK2(V617F)-induced model of myelofibrosis. In conclusion, we here identified two distinct MSC subsets that are pro-fibrotic and contribute to osteosclerosis in PMF. The functional reprogramming of these MSCs in the bone marrow niche was accompanied by expansion of mSCPs with regenerative capacities, most likely caused by neural damage and Schwann cell death triggered by mutant HSCs. Disclosures Crysandt: Amgem: Other: travel grant; Pfizer: Other: travel grant; Gilead: Other: travel grant; Incyte: Membership on an entity's Board of Directors or advisory committees; celgene: Other: travel grant. Koschmieder:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Ariad: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AOP Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CTI: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis Foundation: Research Funding.

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Thrombopoietic Agents in the Treatment of Childhood Immune Thrombocytopenia (ITP): Clinical Treatment At 2 Centers

Blood ◽

10.1182/blood.v118.21.2230.2230 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2230-2230

Author(s):

Kavitha Ramaswamy ◽

Loan Hsieh ◽

Hatice Melda Ürekli ◽

Diane J. Nugent ◽

James B Bussel

Keyword(s):

Bone Marrow ◽

Platelet Count ◽

Board Of Directors ◽

Research Funding ◽

Rescue Therapy ◽

Bone Marrow Fibrosis ◽

Advisory Committees ◽

Equity Ownership ◽

The Mean ◽

Marrow Fibrosis

Abstract Abstract 2230 Introduction: Thrombopoietic agents (TPO-A) are widely used in adults for difficult ITP. However only 1 study has been published describing the use of a TPO mimetic (Nplate) in 22 children with ITP. This study is a post hoc analysis of 32 children (<21yr) who received clinical treatment (off study) with either Nplate or Promacta. Methods: All children described are from 2 centers:,Weill Cornell in New York (n=22, 9 on Nplate, 13 on Promacta) and Childrens Hospital Orange County (10, all on Nplate). All patients in this abstract were treated off study although some had previously participated in the AMGEN195 (Pediatric) followed by AMGEN 213 (long term maintenance) studies. Responses (taken from the published study) were defined as platelet count (plt ct) > 50k on 2 consecutive weeks, plt increase ≥ 20k on 2 consecutive weeks, and the percent of weeks at ≤ 50k independent of rescue therapy. Rescue therapy e.g. IVIG, steroids, plt transfusion, resulted in counts being considered “non-responder” for 2 full weeks after initiation of treatment. Bone marrows were evaluated for reticulin fibrosis (RF) using consensus grades 0–3. Several patients had more than one marrow during treatment; in these cases, the most recent on-therapy marrow was used. Results: The median age of patients on Nplate was 10 years of age (2–19) while for those on Promacta it was 16 years (5–19). Of the 32 patients treated with TPO-A, 24 responded with a plt ct ≥ 50k twice; 19/32 received Nplate and 15/19 responded; 13/32 received Promacta and 9/13 responded. Plt increases ≥ 20k were seen in 23 of 32 patients. The number of patients whose platelet count was ≥ 50k for at least 50 percent of visits was 20/32. The mean number of previous treatments for responders to Nplate was 3.2 while for Nplate non-responders it was 2.25. For Promacta, the mean for responders was 2.9 treatments and for non-responders 3 treatments. Younger patients did not seem to respond as well to treatment with either TPO-A (see table). Nplate patients received treatment for a mean of 19.2 weeks; for patients treated with Promacta it was 13.7 weeks. Baseline bone marrows were available in 17 patients of whom 6 had grade 1 reticulin fibrosis (RF). There were 10 children with marrows performed after the start of TPO-A: 2 with RF score=0, 7 with score=1+, and 1 with score=2+ Adverse events (AEs) other than bone marrow fibrosis and bleeding (lack of efficacy) were all 1–2+ and not related to TPO-A. In particular, no thrombosis or development of malignancy was seen. In conclusion, TPO-A were an effective treatment of chronic ITP in the 32 consecutive children retrospectively analyzed here from 2 centers. Younger children in this study seemed not to respond as well as older children, in contrast to small numbers of young children in published data who responded very well. No major changes were seen in the bone marrows but a formal baseline and on therapy study in children is needed to assess this issue. AEs were infrequent and tolerable. Additional studies with both Nplate and Promacta, either planned or in progress, are needed to clarify the response rates, AEs eg bone marrow fibrosis, and effects in subgroups of children. 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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Bone Marrow Fibrosis In Immune Thrombocytopenia (ITP) Patients Treated With Thrombopoietin Receptor Agonists (TRA) – a Single Center Long-Term Follow-Up

Blood ◽

10.1182/blood.v122.21.3527.3527 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3527-3527

Author(s):

Waleed Ghanima ◽

Julia Turbiner Geyer ◽

Christina Soo Lee ◽

Attilio Orazi ◽

Leonardo Boiocchi ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Research Funding ◽

Single Center ◽

Duration Of Treatment ◽

Bone Marrow Fibrosis ◽

Advisory Committees ◽

Equity Ownership ◽

Marrow Fibrosis

Abstract Introduction TRAs increase platelet counts by stimulating the TPO-receptor. A known effect of TRA treatment is increased bone marrow fibrosis (MF). This study explored extent of MF, its clinical relevance, and incidence of phenotypic or karyotypic abnormalities in TRA-treated ITP patients. Methods This single-center study was carried out at the Platelet Disorders Center of Weill Cornell Medical College (WCMC), NY, USA. Eligibility criteria were: diagnosis of ITP; treatment with a TRA (romiplostim, eltrombopag, AKR 501 (Eisai) or Shionogi agent), ≥ 1 bone marrow biopsy (BMB) performed during TRA treatment. BMBs were performed every 1–2 years as standard f/u procedure for our ITP patients on TRA. MF grade was assessed from MF-0 to MF-3 according to the European Consensus Grading System in 141 BMBs acquired prior to (n=15), during (n=117) and after (n=9) TRA-treatment from 66 patients. Fifty disease-free staging BMBs served as controls. BMBs were separately reviewed by 3 pathologists to assess the grade of MF and then reviewed concurrently as needed to reach consensus. The study was approved by the IRB of WCMC; informed written consent was obtained from patients. Results Median (Q1-Q3) age at the time of 1st BMB was 38 years (18-63); 34 males 32 females. 32 patients had > 2 on-treatment BMBs. The distribution of MF-grades is shown in the figure. The proportion of MF-0 decreased from 67% in pretreatment biopsies (BM0) to 21% in the first set of BMBs (BM1); in the 15 patients with pre- and on-treatment BMBs there was a significantly higher number of MF-0 in BM0 as compared to BM1 (10/15 vs. 3/15;p=0.016) suggesting that TRAs induce fibrosis in treated patients. In patients with multiple on-treatment BMBs (n=32), first on-treatment BMB was graded as MF-1 in 24. In the last set of biopsies (BM-Last) 8 had progressed to MF-2/3, 12 remained MF-1, and 4 became MF-0 illustrating the unpredictability of the future course of MF from the first on-treatment marrow. Nonetheless, a higher number of MF-2/3 BMB was found in BM-Last as compared to BM1 [10 (31%) vs. 3 (9%) of 32; p=0.039]. In 5 patients with MF-2/3 BMB, TRA were discontinued: on f/u 2 had less fibrosis, 1 remained the same, and 2 are awaiting f/u BMB. BMB was graded MF-0 in 54% and MF-1 in 46% of control BMB; no difference was found in the proportion of MF-0/1 and 2/3 in BM0 compared to controls, but increased MF-2/3 was seen in BM-last compared to controls (p<0.001). At BM-last in patients dichotomized by MF-0/1 vs. MF-2/3, differences in hemoglobin levels (13.6 vs. 12.4 g/dl, respectively), absolute neutrophil counts (4.8 vs. 7 x109/L), platelet counts (92 vs. 123 x109/L), and LDH levels (212 vs. 219 U/L) were not significantly different. Of the following 6 clinical factors: age, duration of disease, duration of treatment, splenectomy status, type and dose of agent; only age was significantly higher in patients with MF-2/3 as opposed to MF0/1 at time of BM-last [57 vs. 38 years; p=0.01]. There was a tendency toward longer duration of treatment in patients with MF-2/3 as compared to MF-0/1 (3.6 y vs. 2.7y; p=0.16). Flow cytometric immunophenotyping of BMB in 89 examinations did not reveal emergence of clonal abnormalities. Cytogenetic analysis in 72 BMBs did not show any clonal karyotypic abnormalities. Conclusions This large single center experience indicates that TRAs induce some degree of MF as supported by: 1) decreasing fraction of MF-0 after initiation of TRA, 2) decreasing fraction of MF-0/1 (normal grades of MF) in subsequent on-treatment BMBs, 3) increasing fraction of MF-2/3 (pathological grades) in patients with multiple on-treatment BMBs. Only older age was associated with higher grades of fibrosis. However, MF remained stable in most patients within the range found in normal individuals. Higher grades of MF (MF-2/3) observed in some patients were not clinically significant based on peripheral blood counts. Overall, since a number of patients developed MF-2 and even MF-3, this suggests a risk of progressive fibrosis in approximately 20% of patients. No neoplastic immunophenotypic or karyotypic abnormalities emerged during treatment with TRAs. Annual or bi-annual follow-up with BMB should be carefully considered in TRA-treated patients. Discontinuation of TRA should be encouraged in those who develop/progress to MF-3 and possibly even MF-2 to avoid potential further progression of MF Disclosures: 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; Genzyme: Research Funding; IgG of America: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity’s Board of Directors or advisory committees.

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