Citations

Abstract Background: Chronic GVHD contributes to morbidity and mortality after allogeneic transplantation. Several phase 2 and 3 open label studies suggested that ATLG (formerly referred to as ATG-F) reduces cGVHD without impacting relapse or survival. This report describes the first prospective randomized double blind phase 3 trial to assess the effect of ATLG (Neovii) when added to tacrolimus / methotrexate prophylaxis on cGVHD free survival. Patients and Methods: This study was conducted at 27 sites in the United States and Australia. 260 patients were randomized (132 placebo, 128 ATLG). 6 patients who were randomized never received ATLG/placebo (4 placebo and 2 ATLG). Data presented include the 128 placebo and 126 ATLG patients who underwent treatment and transplant. Patients were ages 18-65 years with a diagnosis of acute myeloid (AML, 64%) or lymphoblastic (ALL, 21%) leukemia in first or subsequent complete remission or myelodysplastic syndrome (MDS, 15%) with less than 10% marrow blasts. Median age was 48 years (18-65) with 55% males. All patients received 8/8 HLA (A, B, C, DR) allele matched unrelated products (80% mobilized peripheral blood, 20% bone marrow). Myeloablative conditioning was with cyclophosphamide and total body irradiation (Cy/TBI, 27%), busulfan and cyclophosphamide (Bu/Cy, 33%), or busulfan and fludarabine (Bu/Flu, 40%). All patients received tacrolimus starting on Day -1 and standard mtx on days 1, 3, 6, and 11 for GVHD prophylaxis. Patients received ATLG or placebo on Days -3, -2, -1 at an ATLG dose of 20 mg/kg per day (60 mg/kg total). The primary endpoint of the study was moderate/severe chronic GVHD free survival. cGVHD was scored by the investigator and then confirmed or overturned by an independent adjudication committee. Secondary endpoints included engraftment, acute GVHD , moderate/severe cGVHD, non-relapse mortality, GVHD and relapse free survival (GRFS), progression free (PFS) and overall survival (OS). The impact of ATLG on immune reconstitution was assessed in 91 patients. Results: Treatment arms were balanced with respect to age, diagnosis, remission status, cytogenetics, graft source (PB or BM), CMV serostatus and conditioning regimen. Median follow up of survivors was 745 days (61, 1425). Regarding the primary endpoint, there was no difference in 2 year moderate/severe cGVHD free survival between ATLG and placebo (48 vs 44%, p = 0.57), nor was there a difference in GRFS (Table 1). Neutrophil engraftment at Day 30 was less in the ATLG arm (85% vs 95%, p=0.00001). Grade 2 or higher infusion reactions were higher in the ATLG arm (16% vs 2.3%, p=0.0001). Reactivation of CMV was similar (27% vs 31%, p=0.58). The Day 180 cumulative incidence of grades 2-4 acute GVHD was lower in the ATLG arm (23 vs 40%, p = 0.003) as was the 2-year cumulative incidence of moderate/severe cGVHD (12 vs 33%, p = 0.000006). However, both 2-year OS and PFS were lower in ATLG treated patients (58 v 76% and 47 vs 67%, respectively) due in part to a higher incidence of relapse (32 vs 19%, p=0.068). Multivariable models confirmed that ATLG was associated with inferior OS, HR 1.85 (1.1-2.9, p=.0075) and PFS, HR 1.63 (1.1-2.41, p=0.015). We then conducted an unplanned post-hoc analysis and discovered a striking influence of conditioning regimen on outcomes. There were no differences in OS or PFS between ATLG and placebo arms in patients receiving Bu/Cy or Bu/Flu but a dramatic difference in patients receiving Cy/TBI conditioning (OS, 88% vs 48% p =0.006 and PFS, 75 vs 29%, p=0.007 in placebo and ATLG arms, respectively). 91 patients (44 ATLG, 47 placebo) participated in the immune reconstitution study. ATLG treatment was associated with lower CD3, CD4, and CD8 counts at Days 30, 100, and 360, respectively. In turn lower CD3, CD4, and CD8 counts assessed as time dependent variables were all associated with inferior OS and PFS as well as higher NRM (data not shown). Conclusion: In this first ever prospective, randomized, double blind trial of ATLG added to tacrolimus /methotrexate in recipients of matched unrelated donor grafts after myeloablative conditioning, there was no significant difference in 2 year moderate/severe cGVHD free survival or GRFS. ATLG did significantly reduce grades 2-4 acute and moderate/severe chronic GVHD. However, overall survival was higher in the placebo arm, driven mainly by patients who received Cy/TBI conditioning. Further analyses are needed to understand the proper role for ATLG in HCT. Disclosures Soiffer: Juno: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Porter:Genentech: Employment; Novartis: Patents & Royalties, Research Funding. Jagasia:Therakos: Consultancy. Szer:Alnylam: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ra Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees. Ritz:Kiadis: Membership on an entity's Board of Directors or advisory committees. Glavin:Neovii Biotech: Employment. Chen:Incyte Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding.

Abstract No laboratory test can predict non-relapse mortality (NRM) after hematopoietic cellular transplantation (HCT) prior to the onset graft-versus-host disease (GVHD). Recently, we have shown that a signature of three GVHD plasma biomarkers (TNFR1, ST2, and REG3α) can predict response to GVHD therapy and NRM at the onset of clinical GVHD (Levine, Lancet Haem, 2015). Our goal in the current study was to identify a blood biomarker signature that could predict lethal GVHD and six-month NRM well in advance of the onset of GVHD symptoms. Patient samples on day +7 after HCT were obtained from 1,287 patients from 11 HCT centers in the Mount Sinai Acute GVHD International Consortium (MAGIC). Samples from two large centers (n = 929) were combined and randomly assigned to a training set (n = 620) and test set (n = 309). 358 patients from nine others centers constituted an independent validation set. The overall cumulative incidences of 6-month NRM were 11%, 12%, and 13% for the training, test, and validation sets respectively. The incidence of lethal GVHD, defined as death without preceding relapse while under steroid treatment for acute GVHD, were 18%, 24%, and 14% in the same groups, respectively. The median day of GVHD onset was 28 days in the training set and 29 days in the test and validation sets. We measured four GVHD related biomarkers [ST2, REG3α, TNFR1, and IL2Rα] in all samples and used the training set alone to develop competing risks regression models that used all 13 possible combinations of one to four biomarkers to predict 6-month NRM. The best algorithm, which we rigorously confirmed through Monte Carlo cross-validation of 75 different combinations of training sets, included ST2 and REG3α. No combination of one, three, or four biomarkers was superior to the combination of these two biomarkers. The day 7 algorithm identified high risk (HR) and low risk (LR) groups with 6-month NRMs of 28% and 7%, respectively (p<0.001) (Fig 1A). The relapse rates did not differ between risk groups so that overall survival (OS) was 60% for HR and 84% for LR (p<0.001) (Fig 1B). When applied to the test set (Fig 1C/D), the algorithm identified 54/309 (17%) of the patients as HR with an NRM of 33% vs 7% for LR patients (p<0.001) and 6-month OS of 57% and 81% for HR and LR patients, respectively (p<0.001). In the independent validation set (Fig 1 E/F), the algorithm identified 72/358 (20%) of the patients as HR with an NRM of 26% vs 10% for LR patients (p<0.001) and OS of 68% and 85% for HR and LR patients, respectively (p<0.001). High risk patients were three times more likely to die from GVHD than LR patients in each cohort (p<0.001) (Fig 2). The GI tract is the GVHD target organ that is most resistant to treatment and represents a major cause of NRM, and we observed twice as much severe GI GVHD (stage 3 or 4) in HR patients as in LR patients (p<0.001, data not shown). The algorithm successfully separated HR and LR strata for 6 month NRM in several groups with differing risks for GVHD and NRM, including donor type, degree. of HLA-match, age group, and conditioning regimen intensity (Fig 3). In conclusion, we have developed a blood biomarker algorithm that predicts the development of lethal GVHD seven days after HCT, which performed successfully in large multicenter validation sets. The GVH reaction is already in progress by day +7, even though clinical symptoms may not occur until days or weeks later. We speculate that the blood biomarker concentrations at this early time point reflect subclinical GI pathology, a notion that is reinforced by the fact that ST2 and REG3α, the two biomarkers in the algorithm, are closely associated with GI GVHD. The algorithm identified HR and LR strata in several patient groups with different overall risk for lethal GVHD (donor, HLA match, conditioning regimen intensity, age). This day +7 algorithm should prove useful in clinical BMT research by identifying patients at high risk for lethal GVHD who might benefit from aggressive preemptive treatment strategies. Disclosures Chen: Novartis: Research Funding; Incyte Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Jagasia:Therakos: Consultancy. Kitko:Therakos: Honoraria, Speakers Bureau. Kroeger:Novartis: Honoraria, Research Funding. Levine:Viracor: Patents & Royalties: GVHD biomarkers patent. Ferrara:Viracor: Patents & Royalties: GVHD biomarkers patent.

Abstract INTRODUCTION Recurrent somatic mutations in the metabolic enzymes isocitrate dehydrogenase 1 and 2 (IDH1/2) confer gain-of-function activity in cancer cells, resulting in accumulation of the oncometabolite, D-2-hydroxyglutarate (2-HG). High levels of 2-HG result in epigenetic changes and impaired cellular differentiation. IDH mutations have been identified in multiple solid tumors and hematologic malignancies. Approximately 6-10% and 9-13% of adults with acute myeloid leukemia (AML) carry mutations in IDH1 (mIDH1) or IDH2 (mIDH2), respectively. AG-120 is a first-in-class, oral, potent, reversible, selective inhibitor of the IDH1 mutant enzyme under evaluation in multiple ongoing single agent and combination clinical trials [NCT02074839, NCT02073994, NCT02632708, NCT02677922]. This is the first report of IDH1 mutation clearance assessed by variant allele frequency (VAF) analysis using next-generation sequencing (NGS) in patients treated on the dose escalation portion of the first-in-human phase 1 study [NCT02074839]. METHODS Patients with advanced mIDH1-positive hematologic malignancies received AG-120 as a single agent orally once daily (QD) or twice daily (BID) continuously in 28-day cycles. Primary objectives were determination of safety, maximum tolerated dose (MTD), and selection of a dose schedule for expansion cohorts and future studies. Secondary objectives included clinical activity assessed by investigators using modified 2003 International Working Group Criteria in AML. Determination of mIDH1 VAF was performed using the FoundationOne® Heme test on mononuclear cells from the bone marrow or peripheral blood at screening and subsequent time points on study. This NGS assay reports IDH1 mutations for samples with VAF ≥1%, with median coverage 500X. Patients with IDH1 mutational clearance (IDH1-MC) were defined as having mIDH1 at baseline and at least one on-study sample with no reported mIDH1. RESULTS Seventy-eight patients were treated in the dose escalation portion, which is now closed to enrollment. As of the data cut-off of May 12, 2016, the median duration on treatment was 3.2 months and 9 (11.5%) patients remain on treatment, with an additional 8 (10.3%) patients transitioned to stem cell transplant. Doses ranged from 300-1200 mg QD with 1 cohort at 100 mg BID. Though the MTD was not reached, the recommended phase 2 dose was determined to be 500 mg QD. The majority of adverse events (AEs) were grade 1 and 2, the most common (≥30%) being diarrhea, fatigue, and nausea; the most common grade ≥3 AEs (≥15%) were febrile neutropenia, anemia, leukocytosis and pneumonia. The most common serious AEs were febrile neutropenia (16.7%) and pneumonia (12.8%). The overall response rate (ORR) was 38.5% (n=30), with 17.9% (n=14) achieving a complete remission (CR). Longitudinal mIDH1 VAF data were available for 51 patients; of these, 22% (n=11) achieved a CR. IDH1-MC was observed in 27.3% (3/11) patients who achieved CR (Figure 1). In contrast, only 1/40 patients who did not achieve CR experienced IDH1-MC. This occurred in a patient with an initially low mIDH1 VAF who had clinical progression despite IDH1-MC (Figure 1, bottom right). In all 3 patients with CR who achieved IDH1-MC, an initial increase in mIDH1 VAF, or early peak, was observed prior to IDH1-MC, suggesting that early clonal expansion might have occurred as part of the mechanism of action of AG-120. CONCLUSION This is the first demonstration that treatment with single agent AG-120 can result in mIDH1 clearance as determined by NGS. Further analysis of the mutational profiles is planned. AG-120, a potent, selective, oral inhibitor of mIDH1 continues to demonstrate a well-tolerated safety profile in patients with advanced hematologic malignancies, and induced objective single-agent durable responses. The data continue to support the efficacy and safety of single agent AG-120 and provide evidence that the underlying biology of the disease is altered by treatment. Figure 1. VAF analysis using FoundationOne® Heme NGS assay in 4 AML patients with IDH1-MC treated with AG-120 Figure subscript: Y-axis is mIDH1 VAF, x-axis is days on treatment. Text indicates investigator-assessed clinical response. CR, complete remission; CRi, CR with incomplete neutrophil recovery; CRp, CR with incomplete platelet recovery; R/R, relapsed/refractory; SD, stable disease; PD, progressive disease; *post-transplant sample Figure 1. VAF analysis using FoundationOne® Heme NGS assay in 4 AML patients with IDH1-MC treated with AG-120. / Figure subscript: Y-axis is mIDH1 VAF, x-axis is days on treatment. Text indicates investigator-assessed clinical response. CR, complete remission; CRi, CR with incomplete neutrophil recovery; CRp, CR with incomplete platelet recovery; R/R, relapsed/refractory; SD, stable disease; PD, progressive disease; *post-transplant sample Disclosures DiNardo: Daiichi Sankyo: Other: advisory board, Research Funding; Novartis: Other: advisory board, Research Funding; Abbvie: Research Funding; Celgene: Research Funding; Agios: Other: advisory board, Research Funding. de Botton:Novartis: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Servier: Consultancy; Pierre Fabre: Consultancy. Stein:Agios: Other: advisory board; Celgene: Other: advisory board; Novartis: Other: advisory board. Roboz:Cellectis: Research Funding; Agios, Amgen, Amphivena, Astex, AstraZeneca, Boehringer Ingelheim, Celator, Celgene, Genoptix, Janssen, Juno, MEI Pharma, MedImmune, Novartis, Onconova, Pfizer, Roche/Genentech, Sunesis, Teva: Consultancy. Pollyea:Alexion: Other: advisory board; Pfizer: Other: advisory board, Research Funding; Ariad: Other: advisory board; Glycomimetics: Other: DSMB member; Celgene: Other: advisory board, Research Funding. Fathi:Bexalata: Other: Advisory Board participation; Agios Pharmaceuticals: Other: Advisory Board participation; Seattle Genetics: Consultancy, Other: Advisory Board participation, Research Funding; Merck: Other: Advisory Board participation; Celgene: Consultancy, Research Funding. Altman:Syros: Honoraria; BMS: Honoraria; Janssen Pharmaceuticals: Honoraria; Novartis: Honoraria. Flinn:Janssen: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead Sciences: Research Funding; ARIAD: Research Funding; RainTree Oncology Services: Equity Ownership. Foran:novartis: Honoraria; Millennium Pharmaceuticals, Inc.: Research Funding; karyopharm: Honoraria; medscape: Honoraria; pfizer: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding. Pigneux:Sunesis: Consultancy, Honoraria; Agios: Consultancy, Honoraria. Kantarjian:ARIAD: Research Funding; Bristol-Myers Squibb: Research Funding; Amgen: Research Funding; Pfizer Inc: Research Funding; Delta-Fly Pharma: Research Funding; Novartis: Research Funding. Liu:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Attar:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Sacolick:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Yen:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Hurov:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Choe:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Wu:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Stone:Amgen: Consultancy; Sunesis Pharmaceuticals: Consultancy; Pfizer: Consultancy; Roche: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy; Celator: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy; Novartis: Consultancy; Jansen: Consultancy; ONO: Consultancy; Juno Therapeutics: Consultancy; Merck: Consultancy; Seattle Genetics: Consultancy; Xenetic Biosciences: Consultancy.

Abstract DNA methylation at cytosine position 5 (5mC) is a genetic modification that regulates gene expression and is critical for cancer initiation and development. The methylcytosine dioxygenase TET2 participates in active DNA demethylation by converting 5mC to 5-hydroxymethylcytosine (5hmC) and its subsequent intermediates thereby regulating gene expression. TET2 gene is frequently mutated in hematological disorders, including 15-25% of myelodysplastic syndrome (MDS) cases. Loss of TET2 function leads to DNA hypermethylation and subsequent dysregulated gene expression in hematopoietic stem cells, and has been considered as an initial step of myeloid malignant transformation including MDS and acute myeloid leukemia (AML). While enzymatic activity of TET2 is well studied, little is known about post-translational modifications (PTMs) that regulate its activity in hematopoietic cells. Lysine acetylation, one of the most crucial PTMs, occurs in a variety of proteins and modulates protein-protein or protein-nucleic acids interactions. Here, we first observed that ectopic expression of histone acetyltransferase EP300 or CREB binding protein (CBP) increased the endogenous TET2 acetylation in 293T cells. Mass spectrometry analysis of TET2 identified several conserved acetylated lysine residues located on the exterior surface of its catalytic domain (CD), which is predicted to be essential for the interaction of TET2 with DNA. Modeling of TET2/DNA interaction using x-ray crystal structure (PDB code: 4NM6) indicates acetylated TET2 interferes with DNA binding thereby impairing the catalytic activity of the enzyme. Like other acetylated proteins, TET2 modification is reversible, since ectopic expression of the protein deacetylase Sirtuin1 (SIRT1) significantly decreases acetylation of TET2. A domain mapping analysis revealed that SIRT1 preferentially interacts with TET2 CD, further supporting the regulatory role of SIRT1 on TET2. To explore the role of SIRT1 mediated deacetylaion of TET2 in more physiological condition, SIRT1 knockdown (KD) MDS-L cells as well as SIRT1 knockout (KO) murine hematopoietic c-kit+ cells were used. In MDS-L cells derived from a MDS patient, SIRT1 KD promoted hyperacetylation of endogenous TET2 which is associated with 50% decrease in 5hmC levels compared to control (p=0.03, n=3). Similarly, SIRT1 KO murine c-Kit+ cells showed TET2 hyperacetylation and 62% decrease in 5hmC compared to wildtype (WT) counterpart (p=0.009, n=5). Phenotypically, the transforming ability of SIRT1 shRNA transduced MDS-L cells was evaluated in vitro through serial replating assay. In contrast to first plating which showed no difference between two groups, the number of colonies derived from SIRT1 KD cells was 2.39 fold higher than that from the control shRNA transduced group after two rounds of replating (p=0.0002, n=3). Importantly, we tested the in-vivo effect of SIRT1 KD on MDS-L cells engrafted in immunodeficient NSGS mice. SIRT1 KD significantly enhanced MDS-L cell engraftment compared to control shRNA (50±5% of human CD45+ cells in SIRT1 KD group vs. 19±4% human CD45+ cells in control group, p=0.003, n=6). Interestingly, increased transformation capacity of SIRT1 KD MDS-L cells was associated with decreased expression of TET2 regulated tumor suppressor genes. For example, expression levels of Mtss1 and Dusp6 were significantly decreased in SIRT1 KD MDS-L cells compared to control shRNA counterpart (Mtss1, 49±5% decrease compared to control, p=0.005; Dusp6, 25±2% decrease compared to control, p=0.01). Similar results were observed in SIRT1 KO cells. The validation of physical binding of TET2 to its targets is ongoing. Moreover, the effect of an SIRT1 allosteric activator-SRT1720 in MDS-L cells is similar to that of Vitamin C, a known TET2 activator. Specifically, SRT1720 significantly increased Mtss1 expression in MDSL cells (p=0.0005, n=3), indicating that SIRT1 agonist may lead to activation of TET2 downstream tumor suppressor genes. In summary, our data demonstrate that TET2 activity can be functionally modified by acetylation and may be enhanced in MDS patients that do not harbor loss-of-function mutations through the SIRT1 mediated deacetylation. These results support further exploration of molecular mechanisms inducing TET2 acetylation, and evaluation of SIRT1 activation as a potential therapeutic approach in MDS. Disclosures No relevant conflicts of interest to declare.

Abstract The optimal source of donor hematopoietic stem cells (HSC) is controversial. Granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood (G-PB) has replaced bone marrow (BM) as the most common allograft source in adults but is associated with donor morbidity and higher rates of chronic graft versus host disease (GVHD) compared to BM. The CXCR4 antagonist plerixafor (Px) mobilizes HSC into the PB (Px-PB) faster than G-CSF and preliminary data suggest both quantitative and qualitative differences in allograft content that may impact clinical outcomes. We sought to assess the efficacy and safety of transplanted allografts collected following mobilization with Px alone in HLA-identical sibling transplantation. This was a Phase II, two-strata, multi-center prospective trial (NCT01696461) to evaluate Px-PB allografts prior to reduced intensity conditioning (RIC) and myeloablative conditioning (MAC) based hematopoietic cell transplantation (HCT). Patients aged 18-65 years with an HLA-ID sibling donor and a hematological malignancy suitable for HCT were eligible. The primary objective was to determine the proportion of donors whose cells could be successfully mobilized and collected with a sufficient CD34+ cell dose using Px as the sole mobilizing agent. Px mobilization was considered successful if ≥ 2.0x10^6 CD34+ cells/kg recipient weight were collected in no more than two leukapheresis (LP) collections. All donors receiving Px were included in the analysis of the primary objective based on the intention-to-treat principle. Secondary objectives included the incidence of acute and chronic adverse events in donors, rates of hematopoietic engraftment, donor chimerism, rates of acute and chronic GVHD, non-relapse mortality (NRM), progression free survival (PFS) and overall survival (OS) for the recipients. From July 2013 to December 2014, 64 donor/recipient pairs were enrolled at 12 centers. Donors received Px at 240μg/kg subcutaneously 4 hours prior to LP. LP was performed processing at least 4X blood volume for up to two consecutive days (a third day was allowed for low CD34+ cell yields after 2 LP procedures) to achieve a target CD34+ cell dose of ≥ 4.0 x 10^6/kg recipient weight with a minimum goal of ≥ 2.0 x 10^6/kg. All allografts were cryopreserved. GVHD prophylaxis included cyclosporine or tacrolimus in combination with methotrexate, mycophenolate mofetil, or sirolimus. G-CSF was given routinely post HCT only to MAC recipients. Patient demographics are provided in Table 1. The median donor age was 56 years (18-65). 64% of the donors were male. Donors underwent one (23%), two (72%), or three (5%) LP procedures. 63 of 64 (98%) donors achieved the primary objective. The median total CD34+ cell dose/kg recipient weight collected within 2 days was 4.6 (0.9-9.6). Maximal donor toxicity following Px injection and LP was grades 0 (30%), 1 (52%), 2 (17%), and 3 (2%). Bloating, flatulence, abdominal pain, headache, paresthesisas, injection site reaction, and dizziness were the most commonly observed toxicities. Bone pain was not observed. The one grade 3 toxicity was a vasovagal episode felt related to LP and unlikely to Px. Toxicities typically resolved within a week of LP. The median follow up is 6.3 months. Median days to ANC (>0.5 x10^9/L) and Platelet count (>20 x 10^9/L) recovery were 13.5 (10-148) and 19 (1-76) after MAC and 14.5 (0-25) and 18 (0-141) after RIC, respectively. The cumulative incidence of acute GVHD grades 2-4 and 3-4 at day 100 were 47% (95% CI: 30-64) and 9% (95% CI: 2-22) after MAC and 19% (95% CI: 6-38) and 5% (95% CI: 0-18) after RIC. Probability of NRM at day 100 was 4% (95% CI: 0-13) and 0% after MAC and RIC, respectively. The probability of OS at day 100 was 97% (95% CI: 88-100) and 90% (95% CI: 78-98) after MAC and RIC, respectively. In conclusion, this is the first multi-center trial to demonstrate that as an alternative to G-CSF, Plerixafor rapidly, safely, and effectively mobilizes sufficient numbers of CD34+ cells from HLA-ID sibling donors for HCT following both RIC and MAC regimens. Engraftment was generally prompt and early results of secondary endpoints in recipients are encouraging. Longer follow-up and more extensive analysis of donor allografts and recipient outcomes will be presented at the time of the meeting. Research support was provided in part by Genzyme, a Sanofi Company. Table 1. Characteristics of recipients Table 1. Characteristics of recipients Disclosures Chen: Bayer: Consultancy, Research Funding. Devine:Genzyme: Research Funding.

Abstract Clinical GVHD staging varies between centers and is not agreed upon by independent reviewers (Weisdorf, BBMT 2003). These inconsistencies help explain why promising GVHD treatments from single center studies have not reproduced in multicenter trials. To address this issue, our international GVHD research consortium has developed guidance that has been refined through consensus following case discussions, resulting in uniform and reproducible GVHD clinical symptom reporting. We record all raw target organ symptom data and apply staging based upon this data (Table 1). Only areas of erythema, bullae and desquamation are quantified because other skin changes are not typical of active GVHD rash. Upper GI symptoms must meet thresholds to diagnose GVHD: anorexia with associated weight loss, nausea and/or 2+ vomiting episodes/day lasting 3+ days. For lower GI GVHD we collect stool volumes excluding formed/mostly-formed stools. Unquantified episodes are counted at 200 ml per episode (3 ml/kg for children <50kg) based upon a chart review of 300 patients with post-BMT diarrhea from any cause. Non-GVHD rectal bleeding that results in flecks or streaks of blood in the stool are ignored for staging. We use the highest daily stool output in the 3 days prior to the diagnosis of lower GI GVHD to determine onset stage and, when available, a 3-day average stool volume for subsequent staging to smooth daily variability. We classify biopsy report interpretation into four standardized categories: Positive (unequivocal presence of GVHD), Equivocal (findings suggestive of GVHD, but the pathologist cannot confirm the diagnosis), Non-diagnostic (no abnormalities or subtle findings insufficient to determine etiology), and Non-GVHD etiology (definitive evidence of another diagnosis without concomitant features suggestive of GVHD). We then combine the biopsy interpretation with clinical decision making to assign an overall confidence level to the diagnosis of GVHD in each target organ (Table 2): Confirmed (positive biopsy, regardless of clinician treatment decision), Probable (GVHD diagnosis is sufficiently favored that treatment is given without a positive biopsy), Possible (symptoms present without a positive biopsy; not treated as GVHD), Negative (no symptoms or symptoms are present but a GVHD diagnosis is not entertained and a non-GVHD etiology is identified). Uniform clinical data collection is essential for future GVHD trials and requires application of clear guidance. While still subject to refinement, these guidelines, in use for 2 years by an international research consortium, are designed to be clear, easy to apply, and for clinical trial use. Table 1. GVHD Target Organ Staging Stage Skin (active erythema only) Liver (bilirubin) Upper GI Lower GI (stool output/day) 0 No active (erythematous) GVHD rash < 2 mg/dl No or intermittent nausea, vomiting or anorexia Adult: < 500 ml/day or <3 episodes/day Child: < 10 ml/kg/day or <4 episodes/day 1 Rash < 25% BSA 2-3 mg/dl Persistent nausea, vomiting or anorexia Adult: 500-999 ml/day or 3-4 episodes/day Child: 10 -19.9 ml/kg/day or 4-6 episodes/day 2 Rash 25 - 50% BSA 3.1-6 mg/dl - Adult: 1000-1500 ml/day or 5-7 episodes/day Child: 20 - 30 ml/kg/day or 7-10 episodes/day 3 Rash > 50% BSA 6.1-15 mg/dl - Adult: >1500 ml/day or >7 episodes/day Child: > 30 ml/kg/day or >10 episodes/day 4 Generalized rash (>50% BSA) and bullous formation or desquamation > 5% BSA >15 mg/dl - Severe abdominal pain with or without ileus, or grossly bloody stool (volume independent) Table 2. Confidence Levels Pathologic evidence Clinician assessment Treatment for acute GVHD Comments Confirmed Unequivocal evidence of GVHD GVHD is the etiology for symptoms Not required GVHD is clearly present even if other etiologies co-exist simultaneously Probable Not required (includes equivocal and non-diagnostic biopsies) GVHD most likely etiology for symptoms Yes GVHD is most likely present but other etiologies may also explain the symptoms and there insufficient evidence to make a confirmed diagnosis Possible GVHD in differential diagnosis (but no treatment is being provided) No GVHD may be present, but other etiologies are favored Negative Unequivocal evidence of a diagnosis other than GVHD (e.g., drug rash) GVHD is not considered as an explanation for the symptoms No and the symptoms resolve without GVHD treatment A "negative" biopsy (e.g., normal skin) is not unequivocal evidence of a diagnosis other than GVHD Disclosures Devine: Genzyme: Research Funding. Chen:Bayer: Consultancy, Research Funding. Porter:Novartis: Patents & Royalties, Research Funding. Levine:Novartis: Consultancy.

Abstract Abstract 2462 Poster Board II-439 The eukaryotic translation initiation factor 5A (eIF5A) is highly conserved and the only known protein to contain the amino acid hypusine. Hypusinated eIF5A and deoxyhypusine synthase, one of the enzymes mediating eIF5A post-translational hypusination, have been identified as markers of neoplastic growth and metastasis, respectively. However, recent studies have indicated that, in its unhypusinated form, eIF5A is pro-apoptotic and thus functionally distinct from hypusine-modified eIF5A. SNS01 is a cancer gene therapy biologic targeted to the treatment of multiple myeloma. SNS01 is comprised of three components: a DNA vector containing a B-cell-specific (B29) promoter driving expression of a pro-apoptotic mutant of eIF5A (eIF5AK50R) that cannot be hypusinated; an siRNA that targets the native hypusinated eIF5A that promotes growth of cancer cells; and a synthetic polymer called polyethylenimine (PEI). RT-qPCR experiments demonstrated that treatment of the human myeloma cell line, KAS-6/1, with SNS01 results in a 90 % reduction in the expression of eIF5A mRNA (mediated by the siRNA) as well as the accumulation of ∼ 22,000 copies of the plasmid-derived eIF5AK50R mRNA per ng of total RNA. SNS01 was found to induce apoptosis in both IL-6-dependent (KAS-6/1) and IL-6-independent (U266) myeloma cell lines and was found to be more effective at inducing apoptosis than PEI nanoparticles carrying either the eIF5A siRNA or the eIF5AK50R plasmid alone. Apoptosis assays were used to optimize the ratio of DNA:siRNA in the nanoparticles and a ratio of 2:1 was found to be optimal for the induction of apoptosis in myeloma cells. The anti-tumoral activity of SNS01 was assessed in SCID mice bearing subcutaneous human multiple myeloma (KAS-6/1) tumors using twice-weekly intra-venous injections and a dose range between 0.15 mg/kg and 1.5 mg/kg. Control mice treated with PEI nanoparticles containing a non-expressing plasmid and a non-targeting siRNA had an average tumor volume of 284 mm3 at the time of sacrifice, whereas mice treated with 1.5 mg/kg or 0.75 mg/kg SNS01 exhibited significant tumor regression and had average tumor volumes of 13 mm3 (95 % inhibition; *p = 0.026) and 24.5 mm3 (91 % inhibition; *p = 0.03), respectively. In addition, for mice treated with 1.5 mg/kg SNS01, there was no evidence of tumors under the skin. Lower doses of SNS01 also demonstrated anti-tumoral activity with mice treated with 0.38 mg/kg and 0.15 mg/kg exhibiting a 73 % and 61 % inhibition of tumor growth, respectively. TUNEL-labeling revealed evidence of apoptotic cells in the treated tumors indicating that tumor regression occurs through the induction of apoptosis. Twice weekly dosing of SNS01 was found to be critical for effective tumor control. In a separate study, twice weekly dosing of SNS01 at 1.5 mg/kg was found to inhibit tumor growth by 88 % (p = 0.01) while once weekly dosing did not significantly reduce tumor burden. Since SNS01 is intended as a therapy for multiple myeloma, a bone marrow neoplasm, the biodistribution of PEI nanoparticles containing a GFP plasmid with the B-cell-specific B29 promoter and a fluorescently (DY547)-labeled siRNA was assessed following i.v. administration in Balb/c mice. The fluorescent siRNA was observed in the liver, lung, spleen, and bone marrow, while GFP expression was primarily observed in the bone marrow. In summary, our preclinical data indicate that systemic administration of SNS01 is an effective anti-cancer therapy in an animal model of multiple myeloma. Additionally, since PEI nanoparticles are taken up by cells of the bone marrow following systemic delivery, SNS01 may be an effective treatment option for multiple myeloma patients and is currently being evaluated for use in clinical trials. Disclosures: Taylor: Senesco Technologies Inc.: Patents & Royalties, stock options. Lust:Senesco Technologies Inc.: Research Funding. Dondero:Senesco Technologies Inc.: Employment, Equity Ownership, Patents & Royalties. Galton:Senesco Technologies Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Donovan:Senesco Technologies Inc.: Research Funding. Thompson:Senesco Technologies Inc.: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.

Background Male breast cancer (MBC) is a rare disease for which there is limited understanding of treatment patterns and prognostic factors. Methods Men with TNM stage I to stage III breast cancer diagnosed between 2004 and 2014 in the National Cancer Data Base were included. Trends in treatment modalities were described using the average annual percentage change (AAPC) and estimated using Joinpoint software for the analysis of trends. Kaplan‐Meier curves and the multivariate Cox proportional hazards regression model were used to compare survival between subgroups and to identify prognostic factors. Results A total of 10,873 MBC cases were included, with a median age at diagnosis of 64 years. Breast‐conserving surgery was performed in 24% of patients, and 70% of patients undergoing breast conservation received radiotherapy. Approximately 44% of patients received chemotherapy, and 62% of patients with estrogen receptor–positive disease received endocrine therapy. Oncotype DX was ordered in 35% of patients with lymph node–negative, estrogen receptor–positive/human epidermal growth factor receptor 2 (HER2)‐negative tumors. During the study period, there was a significant increase in the rates of total mastectomy, contralateral prophylactic mastectomy, radiotherapy after breast conservation, ordering of Oncotype DX, and the use of endocrine therapy ( P < .05). On multivariate analysis, factors found to be associated with worse overall survival were older age, black race, higher Charlson Comorbidity Index, high tumor grade and stage of disease, and undergoing total mastectomy. Residing in a higher income area; having progesterone receptor–positive tumors; and receipt of chemotherapy, radiotherapy, and endocrine therapy were associated with better overall survival. Conclusions Despite the lack of prospective randomized trials in patients with MBC, the results of the current study demonstrated that the treatment of this disease has evolved over the years. These findings further the understanding of the modern treatment and prognosis of MBC, and identify several areas for further research.

OBJECTIVEAlthough intracranial arterial aneurysms (IAAs) of childhood are usually idiopathic, it is possible that underlying arteriopathy escapes detection when using conventional diagnostic tools. Quantitative arterial tortuosity (QAT) has been studied as a biomarker of arteriopathy. The authors analyzed cervicocerebral QAT in children with idiopathic IAAs to assess the possibility of arteriopathy.METHODSCases were identified by text-string searches of imaging reports spanning the period January 1993 through June 2017. QAT of cervicocerebral arterial segments was measured from cross-sectional studies using image-processing software. Other imaging and clinical data were confirmed by retrospective electronic record review. Children with idiopathic IAAs and positive case controls, with congenital arteriopathy differentiated according to aneurysm status (with and without an aneurysm), were compared to each other and to healthy controls without vascular risk factors.RESULTSCervicocerebral QAT was measured in 314 children: 24 with idiopathic IAAs, 163 with congenital arteriopathy (including 14 arteriopathic IAAs), and 127 healthy controls. QAT of all vertebrobasilar segments was larger in children with IAAs (idiopathic and arteriopathic forms) (p < 0.05). In children with congenital arteriopathy without an aneurysm, QAT was decreased for the distal cervical vertebral arteries and increased for the supraspinal vertebral artery relative to healthy children. QAT of specific cervicocerebral segments correlated with IAA size and rupture status.CONCLUSIONSCervicocerebral QAT is a biomarker of arteriopathy in children with IAA, even in the absence of other disease markers. Additional findings suggest a correlation of cervicocerebral QAT with IAA size and rupture status and with the presence of IAA in children with congenital arteriopathy.

ObjectiveDrug‐resistant focal epilepsy is widely recognized as a network disease in which epileptic seizure propagation is likely coordinated by different neuronal oscillations such as low‐frequency activity (LFA), high‐frequency activity (HFA), or low‐to‐high cross‐frequency coupling. However, the mechanism by which different oscillatory networks constrain the propagation of focal seizures remains unclear.MethodsWe studied focal epilepsy patients with invasive electrocorticography (ECoG) recordings and compared multilayer directional network interactions between focal seizures either with or without secondary generalization. Within‐frequency and cross‐frequency directional connectivity were estimated by an adaptive directed transfer function and cross‐frequency directionality, respectively.ResultsIn the within‐frequency epileptic network, we found that the seizure onset zone (SOZ) always sent stronger information flow to the surrounding regions, and secondary generalization was accompanied by weaker information flow in the LFA from the surrounding regions to SOZ. In the cross‐frequency epileptic network, secondary generalization was associated with either decreased information flow from surrounding regions’ HFA to SOZ's LFA or increased information flow from SOZ's LFA to surrounding regions’ HFA.InterpretationOur results suggest that the secondary generalization of focal seizures is regulated by numerous within‐ and cross‐frequency push–pull dynamics, potentially reflecting impaired excitation–inhibition interactions of the epileptic network. ANN NEUROL 2019;86:683–694