Late Breaker Abstract • OFID 2017:4 (Suppl 1) • S737 Conclusions. Surges in MMR administration and heightened community aware- ness during a measles outbreak can result in a large number of VARI, consuming considerable public health resources. When evaluating the need to suspect measles among patients with febrile rash, clinicians should consider time since MMR admin- istration, clinical presentation, and history of measles exposure. Collecting appro- priate specimens for timely virus genotyping could inform appropriate public health action. Disclosures. All authors: No reported disclosures. LB-9. Broad-spectrum Investigational Agent GS-5734 for the Treatment of Ebola, MERS Coronavirus and Other Pathogenic Viral Infections with High Outbreak Potential Robert Jordan, PhD1; Alison Hogg, PhD1; Travis Warren, PhD2; Emmie De Wit, PhD3; Timothy Sheahan, PhD4; Michael Lo, PhD5; Veronica Soloveva, PhD2; Jessica Weidner, PhD2; Laura Gomba, MBA2; Friederike Feldmann, BS3; Jacqueline Cronin, BS3; Amy Sims, PhD4; Adam Cockrell, PhD4; Joy Feng, PhD1; Iva Trantcheva, FPD1; Darius Babusis, MS1; Danielle Porter-Poulin, PhD1; Roy Bannister, PhD1; Richard Mackman, PhD1; Dustin Siegel, PhD1; Adrian Ray, PhD1; Mark Denison, MD6; Christina Spiropoulou, PhD5; Stuart Nichol, PhD5; Tomas Cihlar, PhD1; Ralph Baric, PhD4; Heinrich Feldmann, MD, PhD3; Sina Bavari, PhD2; 1Gilead Sciences, Inc., Foster City, California; 2United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland; 3Laboratory of Virology, Division of Intramural Research, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana; 4Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; 5Centers for Disease Control and Prevention, Atlanta, Georgia; 6Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee Session: 228. Late Breaker Oral Abstracts Saturday, October 7, 2017: 10:30 AM Background. Recent viral outbreaks with significant mortality such as Ebola virus (EBOV), SARS-coronavirus (CoV), and MERS-CoV reinforced the need for effective antiviral therapeutics to control future epidemics. GS-5734 is a novel nucleo- tide analog prodrug in the development for treatment of EBOV. Method. Antiviral activity of GS-5734 has been established in vitro against a wide range of pathogenic RNA virus families, including filoviruses, coronaviruses, and par- amyxoviruses (EC50 = 37 to 200 nM) (Warren et al., Nature 2016; Sheahan et al., Sci Transl Med 2017; Lo et al., Sci Rep 2017). Herein, we describe the in vivo translation of the broad-spectrum activity of GS-5734 in relevant animal disease models for Ebola, Marburg, MERS-CoV, and Nipah. Result. Therapeutic efficacy against multiple filoviruses with 80–100% survival was observed in rhesus monkeys infected with lethal doses of EBOV (Kikwit/1995 or Makona/2014) or Marburg virus and treated with once daily intravenous (IV) admin- istration of 5 to 10 mg/kg GS-5734 beginning 3 to 5 days post-infection (p.i.). In all rhe- sus monkey filovirus infection models, GS-5734 significantly reduced systemic viremia and ameliorated severe clinical disease signs and anatomic pathology. In mice infected with MERS-CoV, twice daily subcutaneous administration of 25 mg/kg GS-5734 beginning 1 day p.i. significantly reduced lung viral load and improved respiratory function. In rhesus monkeys, once-daily IV administration of 5 mg/kg GS-5734 initi- ated 1 day prior to MERS-CoV infection reduced lung viral load, improved clinical dis- ease signs, and ameliorated severe lung pathology. Finally, in African green monkeys infected with a lethal dose of Nipah virus therapeutic once-daily IV administration of 10 mg/kg GS-5734, starting 1 day p.i. resulted in 100% survival to at least day 35 without any major respiratory or CNS symptoms. Conclusion. GS-5734 is currently being tested in a phase 2 study in male Ebola survivors with persistent viral RNA in semen. Lyophilized drug formulation has been developed that can be administered to humans via a 30-minutes IV infusion and does not require cold chain storage. Together, these results support further development of GS-5734 as a broad-spectrum antiviral to treat viral infections with high mortality and significant outbreak potential. Disclosures. R. Jordan, Gilead: Employee, Salary. J. Feng, Gilead: Employee, Salary I. Trantcheva, Gilead: Employee, Salary. D. Babusis, Gilead: Employee, Salary. D. Porter-Poulin, Gilead: Employee, Salary. R. Bannister, Gilead: Employee, Salary R. Mackman, Gilead: Employee, Salary. D. Siegel, Gilead: Employee, Salary A. Ray, Gilead: Employee, Salary, T. Cihlar, Gilead: Employee, Salary. 1689b. Week 48 Results of EMERALD: A Phase 3, Randomized, Non-inferiority Study Evaluating the Efficacy and Safety of Switching from Boosted-protease Inhibitors (bPI) Plus Emtricitabine (FTC)/Tenofovir Disoproxil Fumarate (TDF) Regimens to the Once Daily (QD), Single-tablet Regimen (STR) of Darunavir/ Cobicistat/Emtricitabine/Tenofovir Alafenamide (D/C/F/TAF) in Virologically Suppressed, HIV-1-infected Adults Chloe Orkin, MD1; Jean-Michel Molina, MD, PhD2; Joel Gallant, MD, MPH, FIDSA3; Eugenia Negredo, MD PhD4; Joseph Gathe, MD5; Joseph Eron, MD6; Erika Van Landuyt, MD7; Erkki Lathouwers, PhD7; Veerle Hufkens, MSc7; Romana Petrovic, MSc7; Magda Opsomer, MD7; EMERALD Study Group 1Barts Health NHS Trust, London, UK; 2Department of Infectious Diseases, Saint-Louis Hospital,, Paris, France; 3Southwest CARE Center, Santa Fe, New Mexico; 4Germans Trias i Pujol University Hospital, Badalona, Spain; 5Plaza Medical Center, Houston, Texas; 6University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; 7Janssen Pharmaceutica NV, Beerse, Belgium Session: 188. HIV: Modern ART Friday, October 6, 2017: 2:00 PM Background. EMERALD is evaluating the efficacy and safety of switching from bPI + FTC/TDF regimens (control) to D/C/F/TAF 800/150/200/10 mg in virologically suppressed, HIV-1-infected adults. We present Week 48 primary results. Method. EMERALD (NCT02269917) is a randomized, active-controlled, open-label, international, multicenter, parallel-group, non-inferiority trial. Virologically suppressed (viral load [VL] < 50 c/mL for ≥2 months), HIV-1-infected adults were randomized (2:1) to switch to D/C/F/TAF or continue control. The FDA- stipulated primary endpoint was non-inferiority of D/C/F/TAF vs. control regarding % virologic rebound (confirmed VL ≥ 50 c/mL or premature discontinuations with last VL ≥ 50 c/mL) cumulative through Week 48 (4% margin). Result. 1141 patients were randomized and treated (N = 763 D/C/F/TAF; N = 378 control); median age 46; 18% women; 76% white; 58% on >2 previous ARVs (prior to screening regimen); 15% with previous non-DRV virologic failure (VF). Virologic rebound through Week 48 was non-inferior for D/C/F/TAF (2.5%; n = 19) vs. control (2.1%; n = 8) (Δ0.4%, 95% CI: –1.5%; 2.2%; P < 0.001). Most rebounders (12/19 [63%] vs. 4/8 [50%]) resuppressed by Week 48 without change in therapy. Week 48 virologic suppression rates (VL < 50 c/mL; FDA Snapshot) were 94.9% vs. 93.7% (Δ1.2%, 95% CI: −1.7%;4.1%) and VF rates (VL ≥ 50 c/mL; Snapshot) were 0.8% vs. 0.5% (Δ0.3%, 95% CI: −0.7%;1.2%), with no discontinuations for VF. No resistance-associated muta- tions related to any study drug were observed. Adverse events (AEs) were similar between arms: AE-related discontinuations (1.4% vs. 1.3%); grade 3–4 AEs (6.8% vs. 8.2%); serious AEs (4.6% vs. 4.8%); and no deaths. Renal and bone parameters favored D/C/F/TAF vs. control. TC and LDL-C slightly favored control vs. D/C/F/TAF, with no clinically significant difference in TC/ HDL-C ratio between arms (Table 1). Conclusion. Percentage of virologic rebound after switching to D/C/F/TAF was non-inferior to control cumulative through Week 48, with high suppression rates (94.9%), no resistance development, better bone and renal safety parameters and similar TC/HDL-C ratio. D/C/F/TAF maintains the high genetic barrier to resist- ance of darunavir with the safety advantages of TAF, even in patients with a history of non-DRV VF. Table 1: Changes from baseline at Week 48 in renal, lipid, and bone parameters Disclosures. C. Orkin, Janssen Pharmaceuticals: Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee, Research grant, Speaker honorarium and Travel bursary to attend conference. MSD: Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee, Research grant, Speaker honorarium and Travel bursary to attend conference. Viiv Healthcare: Grant Investigator, Scientific Advisor Downloaded from https://academic.oup.com/ofid/article-abstract/4/suppl_1/S737/4294307 by guest on 21 April 2018