ANTIVIRALS and IMMUNOTHERAPIES in PANDEMIC INFLUENZA IOM Briefing April 4, 2005 Frederick G. Hayden, M.D. Division of Infectious Diseases and International Health University of Virginia School of Medicine

Antiviral Agents for Influenza

Amantadine Prophylaxis During Pandemic Influenza Hayden. J Infect Dis 176:S56, 1997

Chemoprophylaxis of Epidemic Influenza ?= No placebo-controlled study or not reported Efficacy (vs placebo or no drug)

Oseltamivir PEP in Households: Reduction in Influenza Illness, Contact Age No.Observa- tion Osel PEP Efficacy (95% CI) %2%74% 1-5 yrs2036%22%39% (-211%, 88%) 6-12 yrs10922%9%61% (-19%, 87%) Note: All index cases influenza-positive and treated with oseltamivir (ITTI) Hayden et al. JID 189:440, 2004

AMANTADINE TREATMENT OF INFLUENZA A/HONG KONG/68 ILLNESS Amantadine (n=72) Placebo (n=81) P-value Mean age, yrs NS Mean duration of fever, hrs <0.01 Mean duration of symptoms, hrs >0.1 > 5-fold rise HAI titers, % NS Amantadine dose = 100 mg q12h for 7 days Galbraith et al. Lancet II:113, July 17, 1971

Antiviral Treatment of Influenza OutcomeAM/RMZNVOSEL Symptom reliefYes Prevention of complications?Yes Decrease antibiotic use?28%24-40% Decrease hospitalizations??~50% Treatment of viral complications ??? Reduction in transmission? (30%)?? ?= No placebo-controlled study or not reported

Oseltamivir Treatment: Effect on Hospitalizations Hospitalizations% Reduction PlaceboOseltamivir Healthy adults5/662 (0.8%)3/982 (0.3%)60% High-risk + elderly 13/401 (3.2%)6/368 (1.6%)50% Total18/1063 (1.7%)9/1350 (0.7%)59% (P=0.019) Kaiser et al. Arch Intern Med 163:1667, 2003

Oseltamivir and Complications: Retrospective Cohort Study, USA OutcomeExposedUnexposedAdj. Hazard Ratio (95% CI) Age 1-12 Pneumonia Hosp. (n=586) 4 (0.7%) 1 (0.2%) (n=17,886) 453 (2.5%) 120 (0.7%) 0.34 (0.13, 0.90) 0.29 (0.04, 2.07) Age Pneumonia Hosp. (n=10,649) 138 (1.3%) 99 (0.9%) (n=41,007) 885 (2.1%) 510 (1.2%) 0.81 (0.68, 0.97) 0.75 (0.60, 0.93) Age 60+ Pneumonia Hosp. (n=463) 8 (1.7%) 10 (2.2%) (n=3,298) 290 (8.8%) 163 (4.9%) 0.41 (0.20, 0.82) 0.55 (0.29, 1.05) Nordstrom et al. 44 th ICAAC, abst no. V-1260, 2004

Anti-Influenza Agents: Adverse Drug Reaction Profiles AgentADRSeverityFreqDose- related AmantadineCNS GI Mild- severe Mild 10-30% Common Yes RimantadineCNS GI Mild- moderate Mild <10% Common Yes ZanamivirBroncho- spasm Mild- severeVery un- common No OseltamivirGIMildCommonYes

Influenza Antivirals: Pregnancy Risks DrugEmbryo- toxicity* Terato- genicity* Pregnancy category Breast milk excretion AmantadineYesYes + CYes RimantadineYes C OseltamivirNo CYes + ZanamivirNo CYes + RibavirinYes X? * Animal models + Case reports in humans

Drug Resistance in Influenza A Viruses M2 Inhibitor Oseltamivir Magnitude of resistance HighHigh Primary resistance 1-2.5%No Frequency during therapy High Low Rapid development YesVariable Person-person transmission YesNot-to-date Pathogenicity YesReduced* Competition with wild-type Yes*Reduced* *Animal models

NEURAMINIDASE INHIBITORS: Resistance Mechanisms HA mutations –Mutations near receptor binding site –  affinity of HA for sialic acid –  dependence on NA for release NA mutations- vary by type/subtype and drug –Framework- variable cross-resistance Glu119 (  Gly, Ala, Asp, Val), His274Tyr, Asp198Asn –Catalytic site Arg292Lys, Arg152Lys

Detection Of Antiviral Resistant Influenza During Treatment Frequency of resistance OseltamivirM2 inhibitor Out-patient adults Out-patient children 0.4% 5.5% ~30% Inpatient children 18% 80% Immunocompromised ?>33% Roberts N. Phil Trans R Soc Lond 356:1895, 2001 Kiso et al. Lancet 364: 759, 2004

Oseltamivir Resistance In N1 Neuraminidase Single nucleotide substitution ( His274Tyr ) → ↓oseltamivir susceptibility ( ≥ 400–fold ) Frequency drug therapy – Children: 16% (7/43) – Adults: 4% (2/50) Reduced replication in cell culture ( > 2.0 log 10 ) – ↓ infectivity in mouse (1,000-fold) and ferret (100-fold) – Variable↓pathogenicity in ferret Transmissible in ferret model Ives et al. Antiviral Res 5:307, 2002 Herlocher et al. JID 190:1627, 2004

Inhibitors of Influenza A and B Virus Neuraminidases Potent and specific inhibitors of influenza NAs in nM range Varied potencies for NAs of different types (A and B) and subtypes Zanamivir (Relenza TM ) and oseltamivir (Tamiflu TM ) are commercially available Peramivir (BCX-1812, RWJ ) and A are investigational.

NA Inhibitor Resistance Profiles NA mutation NA type/ subtype Susceptibility in the NAI assay (fold  ) OseltamrZanamivirPeramivirA E119VA/N2R (>50)S (1)SS R292KA/N2R (>1000)S (4-25)R (30)S (8) H274YA/N1R (900)S (1)R (40)S (3) R152KBR (>30-750)R (10-100)R (>500)R (150) Gubareva LV. Virus Res 103:199, 2004; Wetherall et al. AAC 41:742, 2003

Antiviral and Immunotherapy Research Topics in Pandemic Influenza Current agents –Decreased/increased dose and duration –Other risk populations; infants, pregnant women, immunocompromised, hospitalized –Delayed treatment benefit (>48 hr) Parenteral route of administration Resistance prevention and management Combinations of antivirals New antiviral targets

Oseltamivir Treatment in Adults: Antiviral Effects Median viral titer, log 10 TCID 50 /ml Treanor et al. JAMA 283:1016, 2000

Oseltamivir Treatment in Children: Antiviral Effects Viral titer log 10 TCID/mL Days Whitley et al. PIDJ 20:127, 2001

Palese P. Nature Med 10:S82, 2004

IV Zanamivir in Experimental Influenza A Double-blind, randomized, placebo-controlled Healthy adults with serum HAI titers < 1:8 IV zanamivir 600 mg q12 hr or saline starting 4 hr before intranasal inoculation with 10 5 TCID 50 A/Texas/36/91(H1N1) –Nasal wash ZNV median ng/ml Outcomes (saline [n=8] vs ZNV [n=7]): –Infection- 100% vs 14%, P<0.005 –Virus shedding- 100% vs 0%, P<0.005 –URI- 100% vs 0%, P<0.005 Calfee et al. Antimicrob Agents Chemother 43:1616, 1999

Calfee et al. AAC 43:1616; 1999 Intravenous Zanamivir in Experimental Influenza A/H1N1 Symptom Score NW Viral Titer

Peramivir Single-Dose Pharmacokinetics Mean plasma concentrations in healthy males: oral solution ng/ml Time

Peramivir Phase 3 Treatment: Quantity of Viral Shedding Treatment Group Days·log TCID 50 /ml P Value Placebo5.61 Peramivir 800/ P= Peramivir P<0.0001

Investigational Anti-Influenza Agents Neuraminidase (NA) inhibitors - Peramivir (oral/IV), A (oral) Long-acting NA inhibitors (LANI) –R (topical), Flunet  (topical) Conjugated sialidase –Fludase™ (topical) HA inhibitors- cyanovirin-N Polymerase inhibitors –siRNA; ribavirin (aerosol/IV/PO) Protease inhibitors –Aprotinin

Yamashita et al. 43 rd ICAAC, abst. no. F-1830, 2003

siRNA Treatment of Influenza A in Mice Tompkins SM, et al. Proc Natl Acad Sci USA. 2004;101:8682 siNP + siPA siGFP * P<0.05

Summary A quantitative assay for human interferon is described. Analysis of lung specimens from 11 fatal cases of influenzal pneumonia revealed a complete absence of interferon. The implications of this finding are discussed. Absence of Interferon in Lungs from Fatal Cases of Influenza National Institute for Medical Research, Mill Hill, London Interferon and Influenza, S Baron and A Isaacs, January 1962

Potential Immunomodulatory Therapies Replacement of deficient responses Stimulation of protective innate immune responses –TLR-4 agonists* Modulation of immunopathologic host responses –Pro-inflammatory cytokines/chemokines/NO Anti-TNF*, corticosteroids Statins, fluoroquinolones, macrolides –Reactive oxygen species N-acetylcysteine, allopurinol*, superoxide dismutase* Potentiation of viral replication  combined antiviral and anti-mediator therapies *Beneficial in murine models of influenza

Effect of Prior Statin Therapy on Sepsis Prospective, observational cohort study 361 hospitalized pts with proven/suspected acute bacterial infection –Statin therapy > 1 mo in 23% –Pneumonia 49%, UTI 39%, cellulitis 12% Outcomes (no statin vs statin): –Severe sepsis- 19.0% vs 2.4% (RR 0.13, ) –ICU admit- 12.2% vs 3.7% (RR 0.30, ) –Mortality day % vs 3.7% (RR 0.43, ) Almog et al. Circulation 110:880, 2004

Time, h *p  0.01 † p  ‡ p  0.05 Placebo Oseltamivir Hayden et al. JAMA 1999 Oseltamivir reduces cytokine levels ‡ * * † IL-6 TNF  IFN  Drug administration Median concentration pg/mL Drug administration

Research Priorities: Short-term (1-2 Years) Obtain data on virologic course and host immune responses in human H5 infections License orally inhaled zanamivir for prophylaxis Study oseltamivir PK + tolerance in infants <1 yr Determine PK and tolerability of IV/IM peramivir Assess long-term (8 –12 weeks) tolerability of oseltamivir and inhaled zanamivir prophylaxis –Trial in risk populations in SE Asia Study H5N1 resistance emergence in animal models and strategies for prevention

Research Priorities: Mid-term (2-5 Years) Test oseltamivir monotherapy vs combination with M2 or ribavirin in high-risk population Develop contemporary virus challenge pools for studies of experimental human influenza –Test candidate immunomodulators and antivirals Test therapeutic efficacy of IVIM peramivir in hospitalized influenza patients Test prophylactic efficacy and tolerability of topical LANI Trial combination of antiviral and immunomodulator therapy

Research Priorities: Longer-term (5-10 Years) siRNA as systemic or topical antiviral New antiviral agents (eg, polymerase) Innate immune effector molecules –Surfactants –Mannose-binding lectins –Defensins Innate immune activation –TLR-3, 4, 7, 8. 9 agonists –NOD receptors Modulation of inflammatory cascades