Bone Marrow Response Research Articles

Treatment of Elderly and Unfit AML Patients with Prolonged Administration of Low Dose Cytarabine and Thioguanine Achieves High Complete Remission Rates in an Outpatient Setting

Background: The treatment of elderly or unfit patients with AML is disappointing with little improvement in the past 30 years. Studies in the 1960s (Clarkson, Cancer 1972) explored the use of prolonged low dose cytarabine (Ara-C) with frequent bone marrow monitoring until marrow hypoplasia. Treatment was given as long as needed with up to 6 weeks continuous therapy with some studies combining with synergistic thioguanine (TG). We developed a modification of the prolonged therapy concept using a 21 day course of low dose subcutaneous Ara-C with TG. Maintenance therapy with the same drugs was given for 2 yrs.Aim: To assess the safety and efficacy of low-dose sc cytarabine in combination with TG in patients with AML.Methods: Patients included (i) de novo AML, aged > 65, or unfit for intensive chemotherapy or (ii) patients >18 yrs with relapsed/refractory (R/R) AML. Patients received repeated administration of cycles of Ara-C 20mg/m2 s/c once daily with TG 40 mg/m2 PO once daily for 21 days. Bone marrow biopsy was performed within 4-7 days of completing the 21-day cycle and if blasts > 5% the next cycle was started immediately.There was no specified limit to the induction cycles which was at the investigators discretion considering patient tolerability. Once remission was achieved cycles were reduced to 14 days every 4-6 weeks for 2 years. Supportive care mandated posaconazole, ciprofloxacin, amoxycillin and pegfilgrastim 6 mg every 14 days continued until remission. Treatment was administered in an outpatient setting and Ara-C was given in the home by community nurses or local medical practitioners. The study was approved by the local hospital Human Ethics Committee and registered on the ANZ Clinical Trials Registry (ACTRN12617000231347).Results: Sixty patients were treated, Median age was 75 (range 72-94), 42 (70%) had de-novo AML and 18 (30%) R/R AML. Presenting WCC ranged from 0.8 to 185. Adverse cytogenetics were present in 40 (66%). In de-novo patients, 17 (40%) had prior haematologic disorders and 4 (10%) were treatment related. Response rates were: complete remission 40% or CR with incomplete count recovery (CRi) 28.5% in the entire cohort giving a response rate of CR+CRi of 68.5%. In the newly diagnosed group CR/CRi was 74%. Responses were also seen in the relapsed/refractory group with 5 of 18 (30%) achieving CR/CRi. The median number of cycles to achieve remission was 2 but some patients required up to 4 cycles. There were 9 (15%) deaths during induction. The median overall survival is 15 months in the de-novo group and 5 months in the relapsed/refractory group. A proportion of patients, 20-25% remain alive and in remission at 3 years post treatment. The main toxicity was as expected in this group of patients with infections predominating. No cases of severe liver toxicity were seen despite the prolonged use of thioguanine.Conclusion: Prolonged therapy with low dose Ara-C and TG can be given as an outpatient in elderly AML patients. Complete remission rates appear equal to or better than other commonly used protocols. Anthracyclines are not used. Toxicity was manageable and mainly neutropenia related but some patients never developed serious infections or required hospitalisation. We suggest that this concept of prolonged low dose cytotoxics with individual patient adjusted therapy based on bone marrow response has been overlooked since it was first proposed 40-50 years ago. Further studies are required to independently confirm these results. DisclosuresNo relevant conflicts of interest to declare.

Disease Burden Subgroup Analysis of Health-Related Quality of Life of Blinatumomab Versus Standard-of-Care Chemotherapy in Patients with Relapsed or Refractory Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia in a Randomized, Open-Label Phase 3 Study (TOWER)

Disease Burden Subgroup Analysis of Health-Related Quality of Life of Blinatumomab Versus Standard-of-Care Chemotherapy in Patients with Relapsed or Refractory Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia in a Randomized, Open-Label Phase 3 Study (TOWER)

Correlations between Pre-Transplant Treatment and Bone Marrow Response with Post-Transplant Outcomes in Patients with Myelodysplastic Syndrome Undergoing Allogeneic Stem Cell Transplantation

Correlations between Pre-Transplant Treatment and Bone Marrow Response with Post-Transplant Outcomes in Patients with Myelodysplastic Syndrome Undergoing Allogeneic Stem Cell Transplantation

Age Subgroup Analysis of Health-Related Quality of Life of Blinatumomab Versus Standard-of-Care Chemotherapy in Patients with Relapsed or Refractory Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia in a Randomized, Open-Label, Phase 3 Study (TOWER)

Background: Despite the availability of new therapies for acute lymphoblastic leukemia (ALL), older patients have historically poor responses to treatment and poor outcomes versus younger patients, with 5-year survival rates of approximately 20% or less. Blinatumomab is a bispecific T-cell engager (BiTE®) antibody construct that redirects cytotoxic T cells to lyse CD19-positive B cells and is approved for the treatment of relapsed or refractory (r/r) B-cell precursor (BCP) ALL and for minimal residual disease-positive ALL in the US. In the phase 3 TOWER study in patients with r/r Philadelphia chromosome-negative (Ph-) BCP ALL who received blinatumomab compared with standard-of-care (SOC) chemotherapy, overall survival was improved (median, 7.7 vs 4.0 months; P=0.01; Kantarjian H, et al. N Engl J Med. 2017;376:836-847), and posttreatment health-related quality of life (HRQoL) across all EORTC QLQ-C30 scales was better (Topp MS, et al. Blood. 2018;131:2906-2914). TOWER efficacy results did not differ by age group. In this subgroup analysis of TOWER, we assessed the HRQoL of older patients versus younger patients who received blinatumomab or SOC chemotherapy.Methods: Patients (N=405) with r/r Ph- BCP ALL were randomized 2:1 to receive 2 cycles of induction blinatumomab by continuous intravenous infusion (n=271) or SOC (n=134). Patients could receive transplant at any time following cycle 1. Those in remission could receive up to 3 consolidation cycles; 12 months of maintenance was allowed for those who received up to 3 consolidation cycles and had bone marrow response. HRQoL was assessed using the EORTC QLQ-C30 Questionnaire on days 1 (baseline), 8, and 15, on day 29 of cycle 1; day 1, 15, and 29 of each consolidation cycle; and at the safety follow-up. The questionnaire included 1 global health status scale, 5 functioning scales, 3 symptom scales, and 6 single-symptom items. For global health status and functioning scales, a higher score indicates better HRQoL; for symptom scales/items, a lower score indicates better HRQoL. A 10-point change was viewed as the minimum clinically important difference in EORTC QLQ-C30 (Zikos E, et al. EORTC. 2016). In this analysis, HRQoL in TOWER was assessed using two different age cutoffs: <35 versus ≥35 years (the randomization stratification in TOWER) and <55 versus ≥55 years (the stratification factor for INO-VATE, a phase 3 trial for another therapy in r/r ALL). Analyses included patients with baseline and ≥1 postbaseline result of any multi-item scale or single-item measure. Mean change from baseline in scores for each scale/item were summarized for cycle 1. Time to deterioration (TTD) analyses assessed the treatment effect based on timing from the initiation of treatment to a ≥10-point decrease for the functional scales and/or a ≥10-point increase for the symptom scales respectively.Conclusions: Consistent with the efficacy results, compared with SOC, blinatumomab improved HRQoL and delayed the deterioration in HRQoL regardless of the age group in patients with r/r Ph- BCP ALL. DisclosuresTopp:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Research Funding; Boehringer Ingelheim: Research Funding; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Research Funding; Regeneron Pharmaceuticals, Inc.: Honoraria, Research Funding. Zimmerman:Amgen Inc.: Employment, Equity Ownership. Dombret:Cellectis: Consultancy, Honoraria, Other: Travel expenses; Servier: Consultancy, Honoraria; Immunogen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; Ambit (Daiichi Sankyo): Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Menarini: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Shire-Baxalta: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Otsuka: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Kite Pharma: Consultancy, Honoraria, Research Funding; Jazz Pharma: Consultancy, Honoraria, Research Funding; Ariad (Incyte): Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Roche/Genentech: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau. Stein:Celgene: Speakers Bureau; Amgen Inc.: Speakers Bureau. Franklin:Amgen Inc.: Employment, Equity Ownership. Cong:Amgen, Inc.: Employment, Equity Ownership. Zhang:Amgen Inc.: Employment, Equity Ownership. Schuh:Amgen Inc.: Consultancy; Pfizer: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Otsuka: Consultancy; Shire: Consultancy; Teva: Consultancy; Jazz: Consultancy.

LCL161, an Oral Smac Mimetic/IAP Antagonist for Patients with Myelofibrosis (MF): Novel Translational Findings Among Long-Term Responders in a Phase 2 Clinical Trial

LCL161, an Oral Smac Mimetic/IAP Antagonist for Patients with Myelofibrosis (MF): Novel Translational Findings Among Long-Term Responders in a Phase 2 Clinical Trial

Clinical Features, Laboratory Characteristics, and Response to Therapy in Patients with Acute Undifferentiated Leukemia

Introduction: Acute undifferentiated leukemia (AUL), also referred to as ambiguous lineage leukemia, has been recognized as a unique entity by the WHO classification of myeloid neoplasms since 2008, and is considered a rare subtype. It is characterized by lacking expression of markers diagnostic of myeloid or lymphoid lineages, and encompasses the provisional entity of myeloid/natural killer (NK) leukemia, which also expresses CD56 and other immature T-cell markers. Small studies have reported that AUL is associated with a poor prognosis; however, cytogenetic and molecular characterization of this subgroup of patients is lacking, as are the long-term outcomes of induction therapy and stem cell transplantation (SCT). The goal of this study was to assess clinical and laboratory data of patients diagnosed with AUL at our institution, focusing on its unique characteristics and response to initial therapy.Methods: Parameters assessed at diagnosis included: initial blood counts, bone marrow (BM) blast cell percentage by morphology, specific phenotypic characteristics of BM blasts, molecular mutations and translocations, as well as cytogenetic abnormalities. Immunophenotyping of BM cells at diagnosis was performed using eight-color flow cytometry. Multi-parameter Cytognos acute orientation tube (ALOT) and the combination of the following antigens were used: CD34/CD117/CD14/CD56/CD36/CD123/HLA-DR/CD45/CD64/CD11c. Data were acquired with FACSCanto II flow cytometer and analyzed with Infinicyt software. Myeloperoxidase staining by fluorescence-activated cell sorting (FACS) was considered negative if <3% of blast population stained positive. Data on BM response to initial therapy, based on morphology, immunophenotyping and biopsy, as well as the 18-month outcome following the diagnosis of the first patient in this cohort were assessed.Results: One hundred and sixteen cases of acute myeloid leukemia were diagnosed at the Rambam Health Care Campus between 11/2016 and 5/2018; 16 (1.4%) of them were defined as AUL, since they did not qualify for myeloid, B- or T-cell lineage according to the WHO classification. CD56 positivity was demonstrated in 8 (50%) cases, 5 of which were also CD7 positive. Patient median age was 63 years, 56% were men. None of the patients was found positive for either NPM1 or FLT3 mutations. Likewise, no core binding leukemias were diagnosed in this cohort. Sixty six percent (10/15) of the BM samples demonstrated cytogenetic and/or FISH abnormalities, with 26% complex karyotype cases, and 20% chromosome 7 aberrancies. All but two patients were treated with AML-oriented therapies. None of the patients achieved remission with induction therapy regardless of whether it included a chemotherapy backbone (82% of patients) or a hypomethylating agent. Seven patients have undergone allogeneic SCT, 4 of whom are in remission to date. Two of the remaining transplanted patients died of progressive disease and one developed extramedullary relapse 6 months post-transplant. While 8/16 (50%) patients are alive at 18-month follow-up, only 4 of them (25%) are in remission. Notably, all of the latter patients are SCT recipients. Six out of 8 CD56-positive patients have died of progressive disease, and the remaining two have not achieved remission.Conclusions: The present study, while confirming the poor prognosis of AUL patients, also suggests that a certain subset of such individuals could benefit from an allogeneic SCT. The high percentage of complex karyotype abnormalities, the lack of NPM1 mutations, and the expression of T/NK cell immaturity markers could partly account for the established poor outcome. However, since other molecular abnormalities described in the AML mutational landscape may be involved in AUL initiation/progression, extensive molecular sequencing of this patient population is required. A better understanding of the unique characteristics of this leukemia subtype is also crucial for the design of potentially improved treatment strategies for AUL patients. DisclosuresNo relevant conflicts of interest to declare.

Granulopoiesis in the Control of Hematopoietic Stem Cell Self-Renewal and Niches

The bone marrow (BM) vasculature is a critical component of the hematopoietic stem cell (HSC) niche. While the mechanisms through which the vasculature regulates HSC are intensively studied little is known about how this vascular niche is regulated and its function in supporting other aspects of hematopoiesis. We have recently shown that, after myeloablation, BM neutrophils are both sufficient and necessary for the regeneration of the vascular niche. This crosstalk is dependent of TNFα secretion by the neutrophil and TNFR1/TNFR2 expression in the stroma (Bowers et al., 2018). We now demonstrate that the crosstalk between neutrophils and the vasculature is bidirectional and that bone marrow endothelial cells provide a niche for fast neutrophil production in response to stress. Emergency granulopoiesis (EG) is the process through which the hematopoietic system generates large neutrophil numbers-at the expense of lymphocyte production-in response to inflammation or infection. A key EG driver is IL1. This cytokine can induce a myeloid bias on HSC and this is thought to be the main mechanism for IL1-driven EG. While characterizing the BM response to IL1 treatment we noted a fourfold reduction in erythropoiesis. Since erythroid- and myeloid- lineage cells differentiate from a common myeloid progenitor downstream of the HSC these results indicated that IL1 acted on other cells during EG. Differentiation analyses showed that IL1 blocks B cell differentiation at the common lymphoid progenitor and Pro-B to Pre-B transition stages whereas loss of erythropoiesis is detected at the pre-MegE stage and remains suppressed through terminal reticulocyte differentiation. IL1 signals, exclusively, through the IL1 receptor (IL1R1). Using reciprocal transplants and mixed chimera experiments we demonstrate that IL1R1 expression in hematopoietic cells is completely dispensable for IL1-driven neutrophil production. Instead, IL1 acts on stromal cells to increase neutrophil production and diminish lymphocyte and erythrocyte production. Our analyses revealed that, in the stroma, only LepR+ perivascular cells and endothelial cells express IL1R1. Conditional Il1r1 deletion in LepR+ cells did not abrogate any of the hematopoietic phenotypes. However, conditional Il1r1 deletion in endothelial cells completely abrogated neutrophil production but did not prevent loss of erythroid and lymphoid lineages. Differentiation analyses showed that, after exposure to IL1, endothelial cells force the differentiation of immature, unipotent, neutrophil progenitors into terminally differentiated neutrophils. These studies thus demonstrate that endothelial cells provide a niche that is indispensable for neutrophil production during EG. This endothelial niche also uncouples neutrophil production from suppression of other hematopoietic lineages opening the door to targeting this pathway to selectively regulate neutropoiesis. Finally these data also highlight the bidirectional communication between the vascular niche and bone marrow neutrophils during stress.Bowers E, Slaughter A, Frenette PS, Kuick R, Pello OM, Lucas D. Granulocyte-derived TNFα promotes vascular and hematopoietic regeneration in the bone marrow. Nat Med. 2018;24:95-102 DisclosuresNo relevant conflicts of interest to declare.

B Cell Precursor Lymphoblastic Leukemia Patients with Good Treatment Response Have Low Levels of Erythroid Precursors

Acute lymphoblastic leukemia treatment leads to elimination of blasts and stepwise regeneration of normal hematopoiesis. Several studies identified prognostic relevance of minimal residual disease (MRD) in bone marrow (BM) before achieving complete remission (Giuseppe Basso et al., J Clin Oncol, 2009). Crucial question is how to assess BM quality at day 15 (d15) of ALL BFM protocols. In ALL BFM 2009 protocol good quality sample is defined as containing more than 2% erythroid precursors (EP) of nucleated cells. EP were defined as CD19neg(orCD7neg)CD45neg.Two pt cohorts were included in the study. First cohort (Coh2000) consisted of pts treated by AIEOP BFM ALL 2000, n=196 (177 BCP ALL, 19 T ALL, median follow-up 5.4 yrs, range 0.025-10). AIEOP BFM ALL 2000 study was a PCR MRD based protocol (assessment at day d33 and d78) and flow cytometric MRD (FC MRD) was assessed only on research basis at d15. Second cohort (Coh2009) consisted of pts treated by AIEOP BFM ALL 2009, n=331 (292 BCP ALL, 39 T ALL, median follow up 4.8 yrs; range 0.0027-7.6). In Coh2009, both PCR MRD (d33, d78) and FC MRD d15 were used for risk stratification.We asked following questions:What is the specificity and viability of EP defined by CD45 negativity? Is a definition based on bright expression CD71 more specific?Is the amount of EP different between B and T ALLs and between risk groups defined by FC at d15? What is the overall frequency of low EP at d15?What is the relationship between amount of EP and FC MRD at d15?Is there any prognostic relevance of low EP?Results:Population of EP was selected based on negativity of CD45 and a lineage marker (CD19 or CD7) among nucleated cells, which were defined as positive by a SYTO nucleic fluorescent dye. We found a high amount of non-viable cells defined by 4′,6-diamidino-2-phenylindole (DAPI) positivity (6.5-96%, median 55%). When we added bright CD71 into the EP definition (EP CD71++), the percentage of DAPI positivity was significantly lower (0-66%, median 9%) (p<0.0001 in both cohorts).There is no difference in amount of EP at d15 between B and T ALL in either of the cohorts. The treatment reduction in SR pts (FC MRD d15<0.1%) was in Coh2009 used only in BCP ALL and we focused in further analyses on BCP ALLs. Overall, the EP were below 2% in 16% and 18% in Coh2000 and Coh2009, respectively. Within risk groups, EP below 2% at d15 occurred more frequently in Standard Risk (SR; 27%) than in non-SR (non-SR; 12%) in both cohorts (p=0.0002). The frequency of low EP appears higher than the expected frequency of technically poor samples. Moreover, it is unlikely that quality of BM aspiration would depend on the risk group of the pt. This further supports the role of normal BM response to presence of leukemic cells on one hand and to therapy on the other one.In both cohorts we found significant positive correlation between amount of EP and FC MRD at day 15 (Coh2000 p-value= 0.0016 (R 0.23); Coh2009 p value <0.0001 (R 0.33)). The correlation was significant in BCP ALLs only (Coh2000 p value=0.008 (R 0.26); Coh2009 p value<0.0001 (R 0.39)). The same significant correlation is observed in BCP ALLs with more precisely defined population EP CD71++DAPIneg (Coh2000 p value=0.04 (R0.18); Coh2009 p<0.0001 (R 0.35)). Part of the Coh2000 was treated with prednisone and part of the pts with dexamethasone between d8 and d28, whereas the entire Coh2009 received prednisone only. However, the frequency of low EP was not different between dexamethasone and prednisone-treated pts, the correlation between FC MRD and EP was significant only in prednisone treated pts (p=0.0003, R=0.33).We focused on SR BCP ALL pts (FC MRD d15<0.1%). We did not find difference in event free survival (EFS) between pts with amount of EP below and above 2%. This result indicates that the pts with low MRD and low EP are not just pts with hemodiluted BM samples.Conclusion: Sample quality is essential question in the assessment of MRD in BM. Although low EP may indicate poor BM aspiration quality, it may also result from other biological factors. At d15 BCP ALL, these factors include the interaction of normal BM cells with leukemia, patient's risk group, and type of corticosteroid used. EPs should be detected using an erythroid marker, such as CD71. However, new markers of BM quality, less influenced by leukemia treatment, are needed.Supported by Ministry of Health of CR, grant nr. 15-28525A, NV18-07-00430 and NV18-03-00343; Czech Science Foundation nr. P302/12/G101. DisclosuresBrüggemann:PRMA: Consultancy; Incyte: Consultancy; Pfizer: Speakers Bureau; Roche: Speakers Bureau; Affimed: Research Funding; Regeneron: Research Funding; Amgen: Consultancy, Research Funding, Speakers Bureau.

Phase 2 Study of Blinatumomab in Japanese Adults with Relapsed/Refractory Acute Lymphoblastic Leukemia (R/R ALL)

Phase 2 Study of Blinatumomab in Japanese Adults with Relapsed/Refractory Acute Lymphoblastic Leukemia (R/R ALL)

Results of a Phase 2 Trial of the Monocyte-Targeted Histone Deacetylase Inhibitor Tefinostat (CHR-2845) in Chronic Myelomonocytic Leukemia (CMML) — the UK Monocle Study

BackgroundChronic myelomonocytic leukemia (CMML) is a highly heterogeneous myeloid neoplasm with poor prognosis and limited therapeutic options. Tefinostat (CHR-2845) is a cell permeant ester that is converted to an active acid histone deacetylase (HDAC) inhibitor (CHR-2847) by human carboxylesterase 1 (hCE-1), an enzyme predominantly found in cells of monocyte lineage. Pre-clinical studies confirmed selective activity of tefinostat, correlating with hCE-1 expression and acetylation induction, in monocyte derived cell lines, primary CMML and AML (M4/M5) cells (1). A phase 1 study in refractory haematological malignancies showed tefinostat to be well tolerated, with complete remission reported in 1/2 CMML patients (2). Given the compelling rationale for selective activity in monocytoid malignancies, we conducted a phase 2 study to assess safety and efficacy of tefinostat in CMML.MethodsMONOCLE was a single arm phase 2 trial conducted to a Bryant and Day 2-stage design with dual primary endpoints of safety and clinical efficacy. CMML-2 patients were included; additionally CMML-1 patients with symptomatic bone marrow failure or proliferative disease, symptomatic splenomegaly, extramedullary involvement, systemic symptoms or CMML-specific Prognostic Score (CPSS) int-2/high. Tefinostat was administered orally in continuous 28-day cycles starting at 360mg once daily, increasing to 480mg after 4 weeks if well tolerated. Concomitant hydroxycarbamide was permitted only with cycles 1-3. Clinical response was assessed according to International Consortium MDS/MPN Response Criteria (3); responding patients at cycle 6 were permitted to continue therapy. Toxicity was assessed according to CTCAE v4.0.ResultsIn stage 1, 21 patients were enrolled at 9 centers (Jan-Sep 2017). 20 patients received tefinostat (median age 75 years [64-88], M/F 14/6) including 16 with CMML-1 (80%) and 4 CMML-2 (20%), 8 (40%) with myelodysplastic and 12 (60%) myeloproliferative CMML; respective proportions in CPSS low/int-1/int-2/high risk groups were 5/50/40/5%. Myeloid NGS analysis confirmed a molecularly relatively high risk population: 70% ASXL1 mutation frequency and median 4 (2-7) mutations per patient; other most commonly observed mutations being TET2 (65%), SRSF2 (50%), EZH2 (35%) and NRAS (35%). Prior therapy included azacitidine (3 patients) and hydroxycarbamide (7). 17/20 patients had high hCE-1 levels, assessed flow cytometrically at trial entry in monocytoid cells (vs bulk myeloid population). Median number of cycles of tefinostat received was 4 (1-15). Of 13 patients completing ≥3 cycles of tefinostat, 1 patient achieved clinical benefit (partial bone marrow response at cycle 6 with red cell transfusion independence sustained over 15 cycles of treatment), 9 had stable disease (of whom 1 had transient clinical benefit [MPN-SAF symptom reduction] which was not sustained to cycle 6) and 3 had progressive disease. Most frequent non-hematologic adverse events of any grade were raised creatinine (55% patients), fatigue (40%) and nausea/vomiting (30%). Grade ≥3 AEs judged potentially related to tefinostat included thrombocytopenia (3 patients), fatigue (2), raised creatinine (2), anorexia, AV block, nausea and neutropenia (1 each). Creatinine rises were in all cases reversible following tefinostat dose reduction/cessation. Induction of intracellular lysine acetylation in monocytes (a marker of HDAC inhibition) was observed in 50% of patients (including clinical responders), peaking between days 15-28 of cycle 1. While no clear relationship between baseline hCE-1 expression and clinical response was evident, reductions in marrow monocyte and myeloid blast fractions were seen in both clinical responders.ConclusionFollowing failure to achieve a pre-defined minimum number of clinical responses to tefinostat, patient recruitment was not continued into stage 2 of this phase 2 study. Drug tolerability was encouraging although observed renal effects will likely preclude dose escalation in this challenging, often frail patient group. Despite compelling scientific rationale and pre-clinical data favoring this monocyte targeted treatment approach we were unable to demonstrate a clinically significant single agent disease modifying effect in CMML.(1) Zabkiewicz J. Oncotarget 2016; 7: 16650-62(2) Ossenkoppele G. Br J Haem 2013; 162: 191-201(3) Savona M. Blood 2015; 125: 1857-65 DisclosuresKnapper:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: Meeting and travel support; Jazz: Other: Meeting and travel support; Daiichi Sankyo: Other: Meeting and travel support; Chroma Therapeutics: Research Funding. Hills:Daiichi Sankyo: Consultancy, Honoraria. Dillon:Teva Pharmaceuticals UK: Consultancy, Honoraria; AbbVie UK: Consultancy, Honoraria. Pocock:Kent & Canterbury Hospital: Employment. Culligan:Pfizer: Honoraria; Takeda: Honoraria, Other: Support to attend conferences; JAZZ: Honoraria; Merck Sharp & Dohme (MSD): Honoraria; Abbvie: Other: Support to attend conferences; Celgene: Other: Support to attend conferences; Daiichi-Sankyo: Other: Support to attend conferences.

Study of Bone Marrow Response to Platelet Transfusion in Severe Traumatic Brain Injury Patients

Introduction: SevereTraumatic Brain Injury (TBI) patients are predisposed to secondary brain insults due to thrombocytopenia and coagulopathy, warranting platelet transfusion. Thrombopoietin (Tpo) has been shown to be a physiological regulator of thrombopoiesis. An inverse correlation between Tpo and the circulating platelet has been previously reported for several clinical conditions. Response pattern of Tpo to circulating platelets in TBI patients has not been studied yet. We hypothesised that in severe TBI patients thrombopoiesis response to TPO will be impairedMethodology: Plasma Tpo levels were measured by enzyme-linked immunosorbent assay was measured 3 times i.e. Pre-platelet transfusion of platelets,24h and 48h post-transfusion in 100 severe (GSC≤8)TBI patients. Platelet transfusion response was evaluated and defined as a ≥20% increase in platelet count from baseline and patients were categorized as responders and non-responders to platelet transfusion.Results: Platelet count was low at admission (89.4±31.1*103 per cumm). Less than 2 units of random donor platelets(RDP) was given to 14% patients,67% patients required2-4 units of RDP and 19% required >4 units of RDP. TPO levels decreased 24h post transfusion compared to pre transfusion (Mean±SD)(127.8±90.2 vs. 142.2±82.6 pg/ml; P 0.07), but elevated at 48h (209.1±74.8 pg/ml; p Pre vs. 48h 0.05). On Average the platelet count improved after transfusion at 24h to 112.7±74.6pg/ml (p Pre vs. 24h 0.003) and continued to rise at 48 h (123.7±82.1 pg/ml; p Pre vs. 48h 0.02). Platelet count and TPO levels were found to be independent (rho -0.12, p 0.38). 62% showed a ≥20% increase in platelet count from baseline (Responders), 38% were non-responders. As significant increase in 24 h post transfusion Tpo levels were seen in responders [median (IQR)] [173.6(0-202.4) pg/ml vs. 164.3(137.1-203.7) pg/ml; p 0.04] compared to pre transfusion levels. Tpo levels in Non-responders did not vary post platelet transfusion [156(0-198.11) pg/ml vs. 158.88(0-198.11) pg/ml; p 0.97]. 28% of Non-responders had low (<81.25 pg/ml) and 2.8% had high (>237.7 pg/ml) pre transfusion Tpo levels. At 24 h post transfusion 26.6% had low and zero had High Tpo levels.Conclusion: In the present study platelet transfusion response inversely correlates with Tpo levels, as 24h post platelet transfusion Tpo levels were transiently low but insignificant and elevated at 48h post transfusion. In non-responders, the post transfusion TPO levels were not sufficient to mitigate the low platelet counts. Hence, the possibility of transient bone marrow depression in severe TBI patients is suggested, which requires further analysis in a larger study cohort. DisclosuresNo relevant conflicts of interest to declare.

Results of a Phase 1, Dose-Escalation Study of FF-10501-01 in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML) or Hypomethylating Agent (HMA)-Resistant Myelodysplastic Syndrome (MDS)

IntroductionFF-10501-01 is an orally bioavailable potent inhibitor of inosine-5-monophosphate dehydrogenase (IMPDH). In vitro, FF-10501-01 reduced the proliferation of multiple human-derived myeloid leukemia parent and hypomethylating agent (HMA)-resistant cell lines in a concentration dependent manner. Incubation of cells with FF-01501-01 also reduced intracellular pools of GMP, GDP and GTP, and this effect was reversed by addition of guanosine, demonstrating that the effect was due to inhibition of IMPDH. FF-10501-01 was evaluated in a Phase 1 clinical trial in patients with relapsed/refractory AML and HMA-resistant MDS and results are presented below.MethodsThis was an open-label, single-institution, Phase 1, dose escalation study in patients with refractory AML and MDS, or in patients with AML > 60 years of age not eligible for other treatment. The study was conducted as a “3+3” design. The objectives of the study were to describe the adverse event profile, pharmacokinetics, pharmacodynamics, recommended Phase 2 dose (RP2D) and preliminary efficacy of FF-10501-01. Oral FF-10501-01 was administered in escalating doses ranging from 50 - 500 mg/m2 twice daily (BID) for periods of 14, 21 or 28 days in a 28-day treatment cycle and dose escalation to the next dose cohort was governed by the decision of a safety review committee. The pharmacokinetics of FF-10501-01 and its primary active metabolite were determined by measuring blood levels at various times after administration; pharmacodynamics were based on measurements of xanthine monophosphate (XMP) at various time points. The institutional review board of the participating institution approved the protocol and all protocol amendments, and all patients provided written informed consent.ResultsThirty-seven patients were treated with FF-10501-01. Most (78%) of patients had AML; the median age of all patients was 78 (range: 58 - 88). All patients had received prior therapy (median number 3, range: 1 - 6) and 3 patients had undergone stem-cell transplantation. FF-10501-01 was well tolerated; the most frequently observed treatment-emergent related adverse events were fatigue (22%), diarrhea (11%), nausea (11%) and oral mucositis (8%). Of all adverse events reported, only 3 were Grade 3 in severity (one episode each of neutropenia, thrombocytopenia and oral mucositis); all others were Grade 1 or 2. The RP2D was determine to be 400 mg/m2 given for 21 days every 28 days. In the MDS cohort, 1 of 8 evaluable patients demonstrated a complete bone marrow response that persisted for 19 months and 3 of 24 evaluable patients with AML demonstrated partial responses; in 1 of these patients, the response persisted for 31 months. One additional patient with AML continued treatment with FF-10501-01 for 14 months without evidence of progression. FF-10501-01 displayed dose proportional pharmacokinetics with no evidence of drug accumulation; mean steady-state observed half-lives ranged from 3 - 9 hours. Blood concentrations of XMP were variable between subjects as a function of dose and time. Following a single administration of FF-10501-01, on average, there appeared to be a reduction in XMP from baseline and maximum inhibition of pre-dose blood concentrations of XMP were consistently near or above 50% following the first administration of FF-10501-01.ConclusionFF-10501-01, was well tolerated and demonstrated evidence of efficacy in a heavily pre-treated population of patients with AML and MDS. FF-10501-01 had predictable pharmacokinetics and pharmacodynamic testing verified its mechanism of action as an IMPDH inhibitor. FF-10501-01 in combination with other agents, is currently undergoing additional clinical testing. DisclosuresKurman:Fujifilm Pharmaceuticals USA, Inc.: Consultancy. DiNardo:Abbvie: Honoraria; Bayer: Honoraria; Medimmune: Honoraria; Agios: Consultancy; Karyopharm: Honoraria; Celgene: Honoraria. Pemmaraju:Affymetrix: Research Funding; SagerStrong Foundation: Research Funding; plexxikon: Research Funding; daiichi sankyo: Research Funding; samus: Research Funding; celgene: Consultancy, Honoraria; abbvie: Research Funding; cellectis: Research Funding; stemline: Consultancy, Honoraria, Research Funding; novartis: Research Funding. Ravandi:Macrogenix: Honoraria, Research Funding; Sunesis: Honoraria; Xencor: Research Funding; Orsenix: Honoraria; Seattle Genetics: Research Funding; Sunesis: Honoraria; Astellas Pharmaceuticals: Consultancy, Honoraria; Xencor: Research Funding; Macrogenix: Honoraria, Research Funding; Bristol-Myers Squibb: Research Funding; Abbvie: Research Funding; Abbvie: Research Funding; Jazz: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Jazz: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Research Funding; Astellas Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Research Funding; Orsenix: Honoraria. Madden:Fujifilm Pharmaceuticals USA, Inc.: Consultancy. Maier:Fujifilm Pharmaceuticals USA, Inc.: Consultancy. Iwamura:Fujifilm Corporation: Employment.

Clinical and Morphologic Predictors of Outcome in a Multicenter Cohort of ITP Patients Treated with Trombopoietin Analogues

Background: The role of bone marrow response in patients with immune thrombocytopenia (ITP) has gained paramount importance since the last 10 years, with the demonstrations that marrow megakaryocytes (MGK) are unable to properly compensate platelets peripheral destruction. TPO receptor agonists (TPOa), namely romiplostim (ROMI) and eltrombopag (EPAG), by stimulating megakaryopoiesis are able to induce a response in 74% to 94% of cases in clinical trials. However, real world use of these drugs has shown frequent changes in individual dose requirement, the possibility of treatment discontinuation, and their effectiveness outside registered indications; moreover, nothing is known about predictors of response.Aim: To evaluate clinical and morphologic predictors of response in a real world cohort of ITP patients treated with TPOa.Methods: ITP patients treated with EPAG and ROMI from September 2009 to May 2018 at seven Italian Centers were evaluated. Clinical and hematologic parameters including treatment response and marrow characteristics were retrospectively collected.Results: Table 1 shows baseline clinical and morphologic characteristics for the 86 cases enrolled, altogether and divided according to the TPOa used: patients were mainly middle-aged females presenting with severe thrombocytopenia; anti-PLT autoantibodies were positive in 32.6% of cases, and 58.1% of cases presented with bleeding, 22% of grade III-IV. All cases had received 1st line treatment with steroids and 43% at list a 2nd line among those listed in Tab1. Pre-TPOa marrow evalutation showed hypocellularity in 30.2% of cases, reticulinic fibrosis in 33.7%, a polyclonal lymphoid infiltrate in 43% (mostly mixed or T-cell), and reduced MGK in 4.7% of patients. Some dysplastic features were present in about 50% of cases, either dysmegakaryopoiesis (46.5%) or dyserythropoiesis (25.6%). Median time from diagnosis to TPOa was 2.4 years (0.1-28.8). Patients were treated for a median of 1.4 years (0.3-10.8), and ORR at 3 months and 9 months were 75.6% (CR 44.2 and PR 31.4%) and 65.1% (CR 36 and PR 29.1%), respectively. Response rates to EPAG and ROMI were comparable. Regarding predictors of response, bone marrow hypocellularity (40 NR vs 21% ORR, p=0.05) and megakaryocytopenia (33 vs 6%, p=0.06) were significantly more frequent among NRs. Other factors associated with poor response were dyserythropoiesis (58 vs 26%, p=0.04) and erythroid hyperplasia (18 vs 8%, p=0.03), and presence of a T cell infiltrate (66 vs 18.9%, p=0.03). Finally, NRs cases showed significantly lower neutrophil counts at baseline (1.9 vs 2.3x103/mmc in ORR, p=0.01), and had been more frequently exposed to cyclosporine or azathioprine (50 vs 18% in ORR, p=0.01).Fifty-five patients are still on treatment, whereas 31 (20 EPAG/11 ROMI) discontinued because of NR or relapse (17), adverse events or intolerance (2); of note, 12 patients with ORR discontinued the drug because of sustained CR, and 7 of them are still in remission. 14/65(21.5%) responding cases (10 EPAG/4 ROMI) lost the response after a median of 6.2 months (1.8-60) and were variably managed (3 splenectomized, 1 switched from ROMI to EPAG, 1 received danazol, 5 were re-treated with EPAG, and the remaining were managed with steroids and supportive treatment). Median RFS was 2.3 years (0.1-10), longer in patients without megakaryocytopenia (9.9+0.5 vs 4.1+0.6, p=0.06), dyserythropoiesis (mean 9.1+0.5 vs 4.9+0.7, p=0.2), and reticular fibrosis (9.6+0.5 vs 5.5+0.6, p=0.08). During EPAG treatment 7 grade adverse events occurred: 2 grade IV (1 stroke with PLT counts of about 30x103/mmc, and 1 NSTEMI 1 month after EPAG discontinuation for sustained CR), 1 grade III pneumonia, and 4 grade I/II transaminase elevation. No events occurred under ROMI.Conclusions: TPOa use in the real world setting confirms their reported efficacy, the option to switch and/or re-treat with either EPAG or ROMI, and the possibility to discontinue the drugs. The presence of hypocellularity and megakaryocytopenia, along with dysplastic features and of a lymphoid T cell infiltrate are associated with a reduced response to TPOa and a shorter RFS. Pre-treatment bone marrow evaluation may give hints to unravel the physiopathologic mechanisms underlying TPOa refractoriness. [Display omitted] DisclosuresRossi:MUNDIPHARMA: Honoraria; JANNSEN: Other; AMGEN: Other: ADVISORY BOARD; PFIZER: Other: ADVISORY BOARD; BMS: Honoraria; NOVARTIS: Honoraria; ROCHE: Other: Advisory Board; ABBVIE: Other: ADVISORY BOARD; TEVA: Other: ADVISORY BOARD; CELGENE: Other: ADVISORY BOARD; JAZZ: Other: ADVISORY BOARD; SANOFI: Other: ADVISORY BOARD; GILEAD: Other: ADVISORY BOARD; SANDOZ: Honoraria.

Abstract 17039: Neutrophil Subset in Blood Contributes to Acute Oxidant Signals in the Bone Marrow, Which Regulate Innate Immune Responses After Ischemic Tissue Damage

Blood neutrophils are short-lived and have distinct subsets. Aged (senescent) neutrophils are cleared by macrophages in multiple organs including bone marrow (BM), at least, in the steady state. It is unknown, after ischemic tissue damage, how these aged-type neutrophils regulate bone marrow microenvironment and impact on downstream bone marrow responses. In a mouse model of critical limb ischemia, we found that CD62L lo aged-type neutrophils that return to the BM, measured by in vivo circulating cell-labeling, are increased (2.1-fold) after acute limb ischemia, which is corresponded with acute increase in CXCR4, a major chemokine receptor promoting BM returning of blood neutrophils (31%). Interestingly, neutrophil uptake by macrophages is reduced (by 76%) in the BM after limb ischemia, suggesting increased retention of blood-derived CD62L lo neutrophils in BM microenvironment after ischemia. We also found, in the BM, that blood-derived neutrophils have higher reactive oxygen species (ROS) than other neutrophils (61% in MFI) and that limb ischemia indeed increases ROS (34%) and oxidized lipid microparticles (61%) in BM plasma in a Nox2 NADPH oxidase-dependent manner. These suggest that increased returning and retention of blood-derived CD62L lo neutrophils in the BM may contribute to oxidant signals in the BM after limb ischemia. Indeed, using aged neutrophils generated ex vivo and adoptive transfer of these cells, we found that aged neutrophils modulate BM innate immune responses after limb ischemia through ROS—reduced activation of hematopoietic stem progenitor cells (50%); increased acute activation of myeloid progenitor cells (4%); and increased acute but inhibited later Ly6C hi inflammatory monocytes/macrophages in the ischemic tissue (72% and 45%, respectively)—resulting in improved tissue recovery from ischemic damage (2.3-fold). In summary, an aged-type neutrophil subset in blood contributes to acute oxidant signals in the BM, which coordinate innate immune responses to promote tissue recovery from ischemic damage.

Total Body Quantification of Active Bone Marrow Response to Chemoradiation Therapy Using FLT PET Images in Pelvic Cancer Patients

To quantify bone marrow radiation dose response using total body bone marrow (TBBM) quantification analysis of sequentially obtained FLT PET images prior to, during, and after chemoradiation therapy in pelvic cancer patients. A total of 33 pelvic cancer patients were enrolled in IRB approved protocols to obtain FLT PET images prior to, during, and after chemoradiation therapy. Pre-therapy images were used as a control for pelvic bone marrow FLT uptake change. Time series FLT PET images were acquired after 1 week (5 fractions) and 2 weeks (10 fractions) during therapy and 30 days and 1 year after therapy was complete. Weekly low dose (20 mAs) attenuation correction CTs (AC CTs) were co-registered to the FLT PET images. All FLT images were resampled according to the voxel size of the AC CT. The region of interest (ROI) was defined as 5cm above the auditory canal to 10cm below the greater trochanter using a threshold value of 300 HU on each AC CT. The resampled FLT images were used to calculate the voxel by voxel FLT uptake value as a surrogate for marrow activity. A TBBM value was calculated by summing each FLT voxel value and normalizing by the number of voxels with the ROI. The results for each subject were averaged over each time point, but all subjects did not complete all time points. TBBM voxel by voxel analysis of bone marrow activity was calculated as a single normalized value for each time point with all available subject data sets: Week 0 (N = 33), Week 1 (N = 31), Week 2 (N = 28), 30 Day (N = 26), and 1 Year (N = 18). The average TBBM activity values using the 300 HU threshold were 1626 ± 434, 1438 ± 334, 1244 ± 294, 1644 ± 341, and 1613 ± 445 for Week 0, Week 1, Week 2, 30 Day, and 1 Year time points respectively. On average, Week 1 TBBM activity was 88% of Week 0 activity and Week 2 TBBM activity was 76% of Week 0 activity. TBBM recovered to within 1% of Week 0 activity 30 days and 1 year after therapy. TBBM variation was relatively high with a coefficient of variation (CV) of 27%, 23%, 24%, 21%, and 28% for Week 0, Week 1, Week 2, 30 Day and 1 Year time points respectively, which is likely due to individual patient variation. Other HU thresholds were used to identify bone, which results in higher or lower absolute values of TBBM activity. However, the relative change was within 1% and the CV was within 5%. This indicates that identifying the boney ROI for TBBM calculation is relatively insensitive to the HU threshold value even with a low quality, low dose CT. This study shows the potential of an image analysis tool that quantifies TBBM activity for pelvic cancer patients before, during, and after chemoradiation therapy. This metric accounts for both bone marrow depletion and compensatory effects. Correlating an individual patient TBBM value to systemic changes in CBCs could enable patient specific therapy that maximizes therapeutic effect while minimizing toxicity.

3D-printed surface promoting osteogenic differentiation and angiogenetic factor expression of BMSCs on Ti6Al4V implants and early osseointegration in vivo

Three-dimensional-printed (3D-P) titanium implants display many advantages, such as design flexibility, higher efficiency, the capability to easily construct complex or customized structures, etc., and is believed to potentially replace traditional implants. However, the biological performance of the 3D-P titanium surface has not been investigated systematically. Herein, we analyzed the surface characteristics of 3D-P Ti6Al4V implants and evaluated the biological responses of bone marrow derived mesenchymal stromal cells (BMSCs) to the 3D-P surface in vitro. Moreover, after implantation into the rat femoral condyle for 3 and 6 weeks, the osseointegration performance was evaluated. The results showed the 3D-P Ti6Al4V implant presented distinct fluctuant macroscale rough surface and relatively better hydrophilicity which enhanced the adhesion, proliferation, osteogenic differentiation and angiogenetic factor expression of BMSCs. Moreover, the in vivo osseointegration performance was also better than that of the control group at the early stage. The present study suggested the 3D-P titanium alloy is a promising candidate to be used as implant material.

The Postinjury Inflammatory State and the Bone Marrow Response to Anemia.

The pathophysiology of persistent injury-associated anemia is incompletely understood, and human data are sparse. To characterize persistent injury-associated anemia among critically ill trauma patients with the hypothesis that severe trauma would be associated with neuroendocrine activation, erythropoietin dysfunction, iron dysregulation, and decreased erythropoiesis. A translational prospective observational cohort study comparing severely injured, blunt trauma patients who had operative fixation of a hip or femur fracture (n = 17) with elective hip repair patients (n = 22). Bone marrow and plasma obtained at the index operation were assessed for circulating catecholamines, systemic inflammation, erythropoietin, iron trafficking pathways, and erythroid progenitor growth. Bone marrow was also obtained from healthy donors from a commercial source (n = 8). During admission, trauma patients had a median of 625 ml operative blood loss and 5 units of red blood cell transfusions, and Hb decreased from 10.5 to 9.3 g/dl. Compared with hip repair, trauma patients had higher median plasma norepinephrine (21.9 vs. 8.9 ng/ml) and hepcidin (56.3 vs. 12.2 ng/ml) concentrations (both P < 0.05). Bone marrow erythropoietin and erythropoietin receptor expression were significantly increased among patients undergoing hip repair (23% and 14% increases, respectively; both P < 0.05), but not in trauma patients (3% and 5% increases, respectively), compared with healthy control subjects. Trauma patients had lower bone marrow transferrin receptor expression than did hip repair patients (57% decrease; P < 0.05). Erythroid progenitor growth was decreased in trauma patients (39.0 colonies per plate; P < 0.05) compared with those with hip repair (57.0 colonies per plate; P < 0.05 compared with healthy control subjects) and healthy control subjects (66.5 colonies per plate). Severe blunt trauma was associated with neuroendocrine activation, erythropoietin dysfunction, iron dysregulation, erythroid progenitor growth suppression, and persistent injury-associated anemia. Clinical trial registered with www.clinicaltrials.gov (NCT 02577731).

Self‐Assembly of L‐Arginine on Electrophoretically Deposited Hydroxyapatite Coatings

AbstractIn this study, L‐Arginine (L‐Arg) molecules are self‐assembled on HA coatings for potential orthopedic applications. By immersing HA coatings in L‐Arg solution in phosphate buffer saline (PBS) with a pH of 7.4 at room temperature for 24 hours, L‐Arg assembled on HA. The samples were characterized by using Scanning Electron Microscopy (SEM), X‐ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflection‐Fourier Transform Infrared Spectroscopy (ATR‐FTIR), X‐ray Diffraction (XRD), Atomic Force Microscopy (AFM) and ninhydrin assay. The response of human bone marrow derived mesenchymal stem cells (hBMSCs) to HA and L‐Arg/HA coatings both in growth and osteogenic differentiation medium are reported. In the growth medium, cells are found to be more spread out on L‐Arg/HA coatings than HA coatings. Moreover, cell aggregates which are indicators of differentiation are observed on HA coatings spontaneously in the growth medium and cell aggregates are only observed on L‐Arg/HA coatings in the osteogenic differentiation medium. Overall, this study showed that L‐Arg self‐assembles on HA and it hinders osteogenic differentiation of hBMSCs in the growth medium.

Improvement in bone marrow infiltration in patients with type I Gaucher disease treated with taliglucerase alfa

Preliminary data suggest a positive effect of taliglucerase alfa on the bone marrow infiltration of Gaucher cells. In this investigator-initiated study, we report the impact of taliglucerase alfa on the bone marrow fat fraction (FF) in 26 patients assessed by quantitative chemical shift imaging (QCSI). Of 15 treatment-naïve patients (median age 48 [range 24–68] years), eight had baseline FF ≤ 0.3, six of those with a FF ≤ 0.23 (‘bone at risk’). All significantly improved from a median baseline FF of 0.24 (0.15–0.32) to 1st year FF of 0.37 (0.25–0.54) and 2nd year FF of 0.42 (0.27–0.59) (p = 0.01). Among the 11 ‘switch-over’ patients (median age 42 [range 33–69] years; median imiglucerase exposure 8 [range 1–17] years), eight had baseline FF ≤ 0.3, five of those with FF < 0.23. All, but one, significantly improved from a median baseline FF of 0.17 (0.08–0.28) to 1st year FF of 0.3 (0.05–0.34) and 2nd year FF of 0.34 (0.08–0.44) (p = 0.03). Two elderly female patients (age 43 and 58 years, with 17 years imiglucerase exposure) who remained at the same enzyme replacement therapy dose, increased from baseline FF of 0.13 and 0.19 to 0.26 at 1 year. Although the number of observations is small, we hypothesize that switching to taliglucerase may result in an improved bone marrow response. A larger study is needed to assess the early benefit of taliglucerase alfa in adult patients with type 1 Gaucher disease on the bone marrow compartment.

Bone marrow cell response after injury and during early stage of regeneration is independent of the tissue-of-injury in 2 injury models.

Selectively recruiting bone marrow (BM)-derived stem and progenitor cells to injury sites is a promising therapeutic approach. The coordinated action of soluble factors is thought to trigger the mobilization of stem cells from the BM and recruit them to lesions to contribute to tissue regeneration. Nevertheless, the temporal response profile of the major cellular players and soluble factors involved in priming the BM and recruiting BM-derived cells to promote regeneration is unknown. We show that injury alters the BM cellular composition, introducing population-specific fluctuations during tissue regeneration. We demonstrate that injury causes an immediate, transient response of mesenchymal stromal cells and endothelial cells followed by a nonoverlapping increase in hematopoietic stem and progenitor cells. Moreover, BM reaction is identical whether the injury is inflicted on skin and muscle or also involves a bone defect, but these 2 injury paradigms trigger distinct systemic cytokine responses. Together, our results indicate that the BM response to injury in the early stages of regeneration is independent of the tissue-of-injury based on the 2 models used, but the injured tissue dictates the systemic cytokine response.-Leitão, L., Alves, C. J., Alencastre, I. S., Sousa, D. M., Neto, E., Conceição, F., Leitão, C., Aguiar, P., Almeida-Porada, G., Lamghari, M. Bone marrow cell response after injury and during early stage of regeneration is independent of the tissue-of-injury in 2 injury models.