agentes quimioterápicos das infecções virais · agentes virucidas • usados principalmente na...
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Agentes quimioterápicos das infecções virais
• Agentes inactivantes das partículas virais -VIRUCIDAS• Agentes inibidores da replicação viral a nível celular - ANTIVÍRICOS• Agentes que modificam ou aumentam a resposta do hospedeiro à infecção -IMUNOMODULADORES
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Agentes Virucidas
• Usados principalmente na prevenção da transmissão• Detergentes, solventes orgânicos (éter e clorofórmio), radiações• Usados no tratamento de lesões mucocutâneas discretas (verrugas, p. exº.)• Crioterapia, laser, podofilina
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Problemas da terapêutica antiviral
• Infecções detectadas em fases avançadas e/ou são infecções de curta duração - Grande proliferação viral
Diagnóstico precoce; Intervenção rápida e poderosa
• Vírus “apodera-se” da célula-alvoDifícil de atingir especificamente o vírus
Efeitos secundários - citotoxicidade
• Rápida evolução viralEstirpes resistentes aos antivirais
• Número restrito de proteínas virais
• Dificuldade em testar os antivirais (ausência de modelo animal; alguns vírus não cultiváveis em laboratório)
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Alvos da terapêutica antiviral
Ligação aos receptores celulares
Penetração e descapsidação
Síntese dos ácidos nucleicos
Transcrição
Síntese das proteínas
Processamento das proteínas
Formação e saída das novas partículas virais
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Vírus Herpes Simplex (HSV)Vírus Varicela-Zona (VZV)
Citomegalovirus (CMV)Vírus da Imunodeficiência Humana (HIV)
Vírus Influenza AVírus Respiratório Sincicial (RSV)
Vírus das Hepatites B e C (HBV, HCV)Papilomavirus Humano (HPV)
Infecções virais tratáveis com anti-víricos
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J Miguel Azevedo Pereira FFUL
cell prior to its competitive inhibition of the viral DNApolymerase [7]. Within an infected cell, the first phosphor-ylation of ACV occurs through the virally encoded thymi-dine kinase (TK), while the second and thirdphosphorylation steps are carried out by cellular kinases.ACV-triphosphate competes with naturally occurringnucleoside triphosphates and is incorporated into theelongating DNA chain as it replicates, resulting in chaintermination. Valacyclovir is the L-valyl ester oral prodrugof ACV that offers improved bioavailability. Penciclovir issimilar to ACV in that it is an acyclic guanosine analog thatacts through a TK dependent phosphorylation pathway.The active form of the agent, penciclovir-triphosphate,also competitively inhibits the replicative function of theviral DNA polymerase, but unlike ACV, penciclovir is notconsidered an obligate DNA chain terminator, owing to thepresence of a 30 hydroxyl group on its acyclic side chain,which can allow for a limited amount of continued chainelongation [2]. Penciclovir has very poor oral bioavailability
and so famciclovir was designed as its diacetylesterprodrug.
In patients with HSV infections that are failing first-linetherapy, alternative therapy with foscarnet or cidofovircan be considered. The clinical utility of foscarnet andcidofovir is somewhat limited by their toxicity profiles,however. Foscarnet is a pyrophosphate analog that rever-sibly inhibits DNA polymerase in many herpesviruses bybinding to and blocking the viral polymerase’s pyropho-sphate binding site, which interferes with pyrophosphatecleavage from incoming deoxynucleoside triphosphatesand impedes viral replication [8]. Foscarnet acts directlyon viral DNA polymerase without requiring activationvia either viral or host phosphorylation. Cidofovir is adeoxycytidine acyclic nucleotide phosphonate analogwith antiviral activity against a broad range of DNAviruses, including herpesviruses [9]. Because it is amonophosphate analog, cidofovir does not require initial
New HSV antivirals: mechanisms and resistance James and Prichard 55
Figure 1
O
HNHN
HO
HO
HO
OH
HO
OH OH
P
O
O
O
O
O
O
O
O
O
O
O
O
S O
O
NH
pritelivivir
cidofovir
acyclovir famciclovir foscarnet valomaciclovir
brincidofovir
amenamevir N methanocarbathymidine
HO
HO
HN
O
OO O
P
N
N
N
N
N
NN
H
N
N
NO O
OSS NH2
N
N
O
O
O
O
O
OH
OH
O OH2N
NH2
H2N
H2N
N N
N N
NN
N NNN
Current Opinion in Virology
P
Inhibitors of herpes simplex virus replication. Most drugs used to treat herpes simplex virus infections target the viral DNA polymerase. Two newmolecules in clinical development target the helicase–primase complex (pritelivir and amenamevir).
www.sciencedirect.com Current Opinion in Virology 2014, 8:54–61
Terapia da infecção por HSV
Inibidores da helicase-primase
Pró-fármaco do cidofovir
Tratamento da infecção pelo HSV Análogos dos nucleótidos
ALVO: DNA polimerase viral
OHO
OH
H2N
O
N
N
N
HN
OHO
OH
N
N
N
N
NH2
OHO
OH
N
N
NH2
O
OHO
OH
O
N
HN
O
Deoxiguanosina Deoxiadenosina Deoxicytidina Deoxitimidina
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Aciclovir (Zovirax) e Valaciclovir
R = H Aciclovir
R = L-valina Valaciclovir
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TK viral
Quinases Celulares
OOP
H2N
O
N
N
N
HN
OHO
H2N
O
N
N
N
HN
Mecanismo de acção
Usos terapêuticos: Infecções pelo HSV-1, HSV-2 e VZV
Actividade: HSV-1>HSV-2>VZV
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Mecanismo de acção
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Tratamento de estirpes HSV resistentes ao Aciclovir
Predominantemente aparecem em indivíduosimunodeficientes e com infecções recorrentes por HSV
Maioritariamente devidas a mutações no gene que codifica para a enzima timidina cinase viral (UL23); em alguns casos as mutações
de resistência ocorrem no gene que codifica para a DNA-polimerase (UL30)
Fármacos alternativos:
cell prior to its competitive inhibition of the viral DNApolymerase [7]. Within an infected cell, the first phosphor-ylation of ACV occurs through the virally encoded thymi-dine kinase (TK), while the second and thirdphosphorylation steps are carried out by cellular kinases.ACV-triphosphate competes with naturally occurringnucleoside triphosphates and is incorporated into theelongating DNA chain as it replicates, resulting in chaintermination. Valacyclovir is the L-valyl ester oral prodrugof ACV that offers improved bioavailability. Penciclovir issimilar to ACV in that it is an acyclic guanosine analog thatacts through a TK dependent phosphorylation pathway.The active form of the agent, penciclovir-triphosphate,also competitively inhibits the replicative function of theviral DNA polymerase, but unlike ACV, penciclovir is notconsidered an obligate DNA chain terminator, owing to thepresence of a 30 hydroxyl group on its acyclic side chain,which can allow for a limited amount of continued chainelongation [2]. Penciclovir has very poor oral bioavailability
and so famciclovir was designed as its diacetylesterprodrug.
In patients with HSV infections that are failing first-linetherapy, alternative therapy with foscarnet or cidofovircan be considered. The clinical utility of foscarnet andcidofovir is somewhat limited by their toxicity profiles,however. Foscarnet is a pyrophosphate analog that rever-sibly inhibits DNA polymerase in many herpesviruses bybinding to and blocking the viral polymerase’s pyropho-sphate binding site, which interferes with pyrophosphatecleavage from incoming deoxynucleoside triphosphatesand impedes viral replication [8]. Foscarnet acts directlyon viral DNA polymerase without requiring activationvia either viral or host phosphorylation. Cidofovir is adeoxycytidine acyclic nucleotide phosphonate analogwith antiviral activity against a broad range of DNAviruses, including herpesviruses [9]. Because it is amonophosphate analog, cidofovir does not require initial
New HSV antivirals: mechanisms and resistance James and Prichard 55
Figure 1
O
HNHN
HO
HO
HO
OH
HO
OH OH
P
O
O
O
O
O
O
O
O
O
O
O
O
S O
O
NH
pritelivivir
cidofovir
acyclovir famciclovir foscarnet valomaciclovir
brincidofovir
amenamevir N methanocarbathymidine
HO
HO
HN
O
OO O
P
N
N
N
N
N
NN
H
N
N
NO O
OSS NH2
N
N
O
O
O
O
O
OH
OH
O OH2N
NH2
H2N
H2N
N N
N N
NN
N NNN
Current Opinion in Virology
P
Inhibitors of herpes simplex virus replication. Most drugs used to treat herpes simplex virus infections target the viral DNA polymerase. Two newmolecules in clinical development target the helicase–primase complex (pritelivir and amenamevir).
www.sciencedirect.com Current Opinion in Virology 2014, 8:54–61
Ganciclovir (Cytovene)
Activo sobre HSV-1, HSV-2, VZV, EBV, HHV-6, HHV-8, e principalmente
CMV
Administrado profilaticamente parece reduzir a incidência de
CMV nos indivíduos com SIDA
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Cidofovir
Análogo do nucleótido desoxicitidina (fosforilado)
Espectro de acção alargado: HSV, VZV, CMV (tratamento e
profilaxia), e papilomavirus, poliomavirus, adenovirus e
poxvirus
Usado em infecções por HSV devidas a mutantes resistentes
ao aciclovir (UL23)
128 E. De Clercq / Journal of Clinical Virology 30 (2004) 115–133
O
OH
N
N
N
HN
H2 N
O
O
C
OHCH2N
CHH3C CH3
Valganciclovir
Fig. 29.
◦ Administered: orally at 900mg per day (two 450mgtablets daily) for maintenance therapy (900mg twicedaily for induction therapy).
• Foscarnet◦ Structure (Fig. 30): trisodium phosphonoformate, fos-carnet sodium, Foscavir®.
◦ Activity spectrum: herpesviruses (HSV-1, HSV-2, VZV,CMV, etc.) and also HIV.
◦ Mechanism of action: pyrophosphate analogue, inter-feres with the binding of the pyrophosphate (diphos-phate) to its binding site of the viral DNA polymerase,during the DNA polymerization process.
◦ Principal indication(s): CMV retinitis in AIDS pa-tients, and mucocutaneous acyclovir-resistant (viralTK-deficient) HSV and VZV infections in immuno-compromised patients.
◦ Administered: intravenously at 180mg/kg per day(3 × 60mg/kg, every 8 h) for induction therapy ofCMV retinitis; intravenously at 120mg/kg per day(3 × 40mg/kg, every 8 h) for maintenance therapy ofCMV retinitis and for therapy of acyclovir-resistantmucocutaneous HSV or VZV infections in immuno-compromised patients. Dose adjustments for changesin renal function are imperative.
• Cidofovir◦ Structure (Fig. 31): (S)-1-(3-hydroxy-2-phosphonyl-methoxypropyl)cytosine (HPMPC), (CDV), Vistide®,ForvadeTM.
◦ Activity spectrum: herpesviruses (HSV-1, HSV-2,VZV, CMV, etc.), papilloma-, polyoma-, adeno- andpoxviruses.
3 Na+P-O
O
O-
CO
O-
Foscarnet
Fig. 30.
N
N
O
NH2
P O
OH
O
HO
HO
Cidofovir
Fig. 31.
◦ Mechanism of action: targeted at the viral DNA poly-merase, acts as chain terminator, following intracellu-lar phosphorylation to the diphosphate form, and in-corporation at the 3′-end of the viral DNA chain (twosequential incorporations needed for chain terminationin the case of CMV DNA synthesis) (Scheme 9).
◦ Principal indications(s): officially licensed for the treat-ment of CMV retinitis in AIDS patients. Also shownto be effective in the treatment of acyclovir-resistant(viral TK-deficient) HSV infections, recurrent genitalherpes, genital warts, CIN-III (cervical intraepithelialneoplasia grade III), laryngeal and cutaneous papillo-matous lesions, molluscum contagiosum lesions, orf le-sions, adenovirus infections and progressive multifocalleukoencephalopathy (PML).
◦ Administered: intravenously (Vistide®) at 5mg/kg perweek during the first 2 weeks, then 5mg/kg everyother week, with sufficient hydration and under coverof probenecid to prevent nephrotoxicity. Can also beadministered topically as a 1% gel or cream.
• Fomivirsen◦ Structure (Fig. 32): antisense oligodeoxynucleotidecomposed of 21 phosphorothioate-linked nucleosides,ISIS 2922, Vitravene®.
◦ Activity spectrum: CMV.◦ Mechanism of action: being complementary in basesequence, it hybridizes with, and thus blocks expres-sion (translation) of, the CMV immediate early 2 (IE2)mRNA.
◦ Principal indication(s): CMV retinitis (in AIDS pa-tients).
◦ Administered : intraocularly (intravitreally).
5'-d-[G*C*G*T*T*T*G*C*T*C*T*T*C*T*T*C*T*T*G*C*G]_3'sodium salt
* = racemic phosphorothioate
Fomivirsen
Fig. 32.
Treatment of chronic HBV infection
• Interferon-alpha pegylated interferon-alpha (48 weeks)
• Nucleoside analogs:
‣ lamivudine
‣ entecavir
‣ telbivudine
‣ Emtricitabine
• Nucleotide analogs
‣ Adefovir
‣ Tenofovir
➡ long duration >1 y; probably lifetime
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Terapêutica anti-HBV
Hepatology - A clinical textbook
108
Pregnancy is usually a contraindication for all available drugs. Therapy with • nucleos(t)ide analogues during pregnancy may be considered if the benefit out-weighs the risk.
Occupational and social aspects and extrahepatic complications may justify • therapy in individual cases (Cornberg 2007).
Treatment options for chronic HBV infectionThere are two classes available for the treatment of chronic HBV infection: interferon
(standard or pegylated (PEG)-IFN ) and inhibitors of the HBV polymerase, the nucleoside and acyclic nucleotide analogues.
While IFN has been a mainstay in the treatment of chronic HBV infection for many years it is limited by its tolerability and side effect profile allowing administra-tion for only a limited period of time (6-12 months, maximum 24 months). Nucleo-side and nucleotide analogues have a better tolerability and are therefore applied in the long-term treatment of chronic hepatitis B. However, the efficacy of these oral agents can be hampered by the risk of the emergence of resistance. Two interferons and five oral antivirals are currently approved for the treatment of chronic HBV infec-tions: standard IFN -2b and PEG-IFN -2a, lamivudine (LAM), adefovir dipivoxil (ADV), telbivudine (LdT), entecavir (ETV) and tenofovir disoproxil fumarate (TDF) (Table 2). The efficacy of the available drugs after one year of treatment, assessed by the proportion of individuals with HBV DNA below the limit of detection, normalized transaminases and HBeAg seroconversion is shown in Figure 4.
Agent Name Dose Duration
Interferon Standard Interferon -2a Roferon® 2.5-5 mi. IU per 4-6 months m2 body surface 3x/week
Standard Interferon -2b Intron A® 5-10 mi. IU 3x/week 4-6 months
Pegylated Interferon -2a Pegasys® 180 µg/week 48 weeks
Nucleoside analoguesLamivudine Zeffix® 100 mg/day long-term*
Telbivudine Sebivo® 600 mg/day long-term*
Entecavir Baraclude® 0.5 mg/day long-term* 1 mg/day for patients with long-term* lamivudine resistance
Nucleotide analogues Adefovir dipivoxil Hepsera® 10 mg/day long-term*
Tenofovir disoproxil fumarate Viread® 300 mg/day long-term*
* see Figure 7
Table 2. Overview of interferons and oral antiviral drugs currently approved for the treatment of HBV infection.
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T h e n e w e ng l a nd j o u r na l o f m e dic i n e
n engl j med 355;23 www.nejm.org december 7, 20062446
Interferonalfa
Interferonreceptors
Tyrosinekinase
Janus-activatedkinase
STAT
STAT
ViralRNA
P
P
P
HCV
STAT1
STAT2
IRF9
ISGF3
ISRE
ISG mRNAs
OtherISGs
Proteinkinase R
HCV replicativecomplex
Assembly
HCV virions
Adenosinedeaminase
Host DNA
2',5'oligoadenylatesynthetase
Figure 1. Proposed Mechanisms of Action of Interferon Alfa against HCV.
Interferon alfa engages receptors on the hepatocyte cell-surface membrane, causing them to dimerize and to activate Janus-activated and tyrosine kinases that phosporylate the cytoplasmic signal transducers and activators of transcription (STAT) proteins. STAT1 and STAT2 dimerize and bind interferon regulatory factor 9 (IRF9), creating a large complex (interferon-stimulated gene factor 3, or ISGF3) that is translocated into the nucleus, where it binds to interferon-stimulated response elements (ISREs) on DNA. This engagement causes transcription of multiple (>100) interferon-stimulated gene (ISG) mRNAs, which exit the nucleus and encode proteins that alter cell metabolism and interfere with virus replication, protein synthesis, and assembly. Major ISGs thought to be important in inhibiting HCV replication include 2',5' oligoadenylate synthetase, which activates antiviral RNases; RNA-specific adenosine deaminase, which edits viral RNA; and protein kinase R, which inactivates protein translation from viral mRNA. The HCV replicative complex is associated with the cytoplasmic membranes of hepatocytes and comprises RNA replicative intermediates, viral mRNA, structural and nonstructural viral proteins, and assembling virions.
The New England Journal of Medicine
Downloaded from nejm.org at FACULDADE MEDICINA UNIV DE LISBOA on November 25, 2011. For personal use only. No other uses without permission.
Copyright © 2006 Massachusetts Medical Society. All rights reserved.
2’,5’-oligoadenilato sintetase: activação de RNAses virais
Proteína cinase R: inactiva a tradução
RNA-specific adenosine deaminase: edição do RNA viral
Hoofnagle. NEJM 2006, 355:23
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Terapêutica anti-HBV (NA ou NtA)
• Alvo: DNA-polimerase viral (RT)
• Inibe a conversão de pgRNA em DNA genómico
• Cura = desaparecimento do cccDNA…
Standard therapy for hepatitis B virus infection
121
HBV DNA as a parameter of response to antiviral therapyDuring antiviral therapy, the decrease of HBV DNA levels from baseline is the most important tool in monitoring treatment efficacy. Complete response to antiviral thera-py is defined as suppression of HBV DNA to below the limit of detection as measured by a sensitive real time PCR assay (Figure 7). Incomplete suppression is characterized by persistent HBV replication despite antiviral therapy. Ongoing HBV replication should be avoided to prevent the selection of resistant HBV strains by replication of the virus in the presence of drug in the so called “plateau phases”. An HBV DNA breakthrough despite continuous antiviral therapy is often caused by viral resistance. Measuring of HBV DNA kinetics early during therapy will help to guide antiviral treatment and to establish early stopping rules or add-on strategies to avoid antiviral failure (Figure 7).
Figure 7. Possible courses of antiviral treatment with nucleoside/nucleotide analogues. Incomplete suppression of HBV DNA results in either a “plateau phase” or in a continuous slow decline. A plateau phase represents a high risk for selection of resistant HBV variants, therefore treatment should be changed to a more effective agent or combination therapy. A continuous slow decline should induce a treatment change after 6 months if drugs with a low genetic barrier like LAM or LdT are used. If drugs with a high genetic barrier like ETV or TDF are applied, a continuous slow decline can be monitored for at least 12 months without increased risk of consecutive HBV resistance.
Incomplete or partial virologic response to oral nucleoside or nucleotide analogues is defined as a decrease of HBV DNA >1 log but remaining measurable (Lavanchy 2004) (Figure 7). The definition of partial response depends on the type of treatment; thus, for agents with a high genetic barrier against resistance like ETV, ADV or TDF partial response is defined after 12 months and for substances with a low genetic bar-rier against HBV resistance like LAM or LdT, after 6 months of monotherapy. In case
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Viruses 2010, 2
1284
Figure 2. Cumulative incidence of HBV resistance to lamivudine (LAM), adefovir (ADV), entecavir (ETV), telbivudine (LdT) and tenofovir (TDF) in published pivotal trials in NUC-naive patients. For method of calculation, see [61]. These trials included different populations, used different exclusion criteria and different follow-up endpoints [151].
3.2. Adefovir dipivoxil
Adefovir (or PMEA [9-(2-phosphonylmethoxyethyl)adenine]) is an acyclic nucleoside phosphonate [66]. To increase its oral availability, PMEA has been esterified to its prodrug bis(POM)PMEA (Figure 1B). Adefovir dipivoxil was licensed as Hepsera® in September 2002 for the treatment of CHB. It is administered orally at a dose of 10 mg daily.
When PMEA enters the cell, it is phosphorylated twice by AMP kinase [67] to its active form PMEApp, which is incorporated into the growing HBV DNA chain, where it acts as (i) an obligatory chain terminator [68] and/or (ii) a competitive inhibitor of the natural substrate dATP. In addition to its anti-HBV activity, PMEApp has also demonstrated activity against other viruses, i.e., herpesviruses and retroviruses as well as bacteria producing adenylate cyclase toxins (e.g., B. anthracis, B. pertussis, P. aeruginosa) [69]. Treatment for 48 weeks with adefovir dipivoxil led to a decrease of both cccDNA and HBsAg levels in HBeAg-positive CHB patients; it has been estimated that it may take approximately 14.5 years to clear infected cells from cccDNA [70].
Evolução virológica
após terapêutica
Fármacos antivirais (SOC - standard of care)Interferão alfa
15-20% de resultados satisfatórios após 6 meses de tratamento; 25-30% após 12-18 meses de tratamentogenótipos virais 1 e 4 menos susceptíveisTempo de semi-vida superior no caso de interferão alfa pegilado (PEG-Intron®)
Ribavirina
HCV - Tratamento
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Análogo da guanosina
Fosforilado intracelularmente a
mono-, di-, e trifosfato por acção de quinases
celulares
Ribavirina
OHO
OH
H2N
O
N
N
N
HN
OH
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IMP-desidrogenase
Inosina monofosfatoIMP
Xantosina monofosfato
Guanosina monofosfatoGMP
Ribavirina monofosfato
Consequência: Diminuição dos níveis intracelulares de GTP
Ribavirina - Mecanismo de acção
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Outros mecanismos
Inibição da enzima guanilil-transferase (GTP-dependente) que leva à síntese de RNAm com
extremidades anormais provocando uma tradução ineficaz
Efeitos inibitórios directos sobre a RNA-polimerase RNA-dependente de origem viral
Ribavirina - Mecanismo de acção
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Ribavirina - Usos terapêuticos
Activo sobre HCV
Vírus Respiratório Sincícial (RSV) (aerossol) Vírus da Febre de Lassa (IV)
Vírus Hantaan (IV) Vírus Influenza (aerossol)
Efeitos secundários Anemia
Linfopénia Potencialmente oncogénico e teratogénico
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Esquema terapêutico
26 | Hepatitis C Treatment
Table 1.2 – First-line treatment recommendations for antiviraltherapy in Hepatitis C*HCV
Genotypes
PegIFN alfa-2a
once per week
PegIFN alfa-2b
once per week
RBV
once per dayPlanned
duration†
1 and 4 180 µg
Flat dose
1.5 µg/kg
weight-based
dose
15 mg/kg weight-
based dose
48 weeks
800 mg daily
flat dose, if BMI<25
2 and 3 180 µg
Flat dose
1.5 µg/kg
weight-based
dose15 mg/kg weight-
based dose, if
BMI>25
24 weeks
*According to data from EASLD 2011
†Treatment duration should be tailored to the on-treatment virological response
at weeks 4 and 12, and eventually, week 24.
For RGT, the following recommendations can be made
(Tsubota 2011):
– Treatment duration can be reduced to 12 weeks for
genotypes 2/3 infected patients who obtain an RVR with
PegIFN and weight-based RBV dosing. This does not
compromise the likelihood of achieving an SVR, but reduce
the AEs and the associated costs.
– Treatment duration can be reduced to 24 weeks for
genotype 1 infected patients with low baseline
(pretreatment) VL who attain a RVR.
– Treatment may be extended to 72 weeks for genotype 1
infected patients who show a slow virological response (with
partial EVR and HCV RNA negative by week 24). However,
for those who do not attain an EVR, the chance of treatment
success is very low (Thomson 2008).
In the clinical trials of the new direct-acting antivirals, a new
marker has been implemented, namely extended RVR (Sherman
2010). Extended RVR (eRVR) is defined as undetectable HCV
RNA at week 4 of therapy, maintained through a later time point
(in some cases over a period of 12 weeks, in others over 24
weeks). eRVR is a good predictor of the ability to shorten triple
therapy with protease inhibitors. Patients with G1 HCV, who
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HCV - tratamento
Percentagem de cura (IFN + RBV)
Genótipo 1: 50%
Genótipo 2: 90%
Genótipo 3: 80%
Genótipo 4: 70%
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Direct-acting agents (DAA) Protease and polymerase inhibitors
BoceprevirTelaprevir
SofosbuvirDasabuvir
SimeprevirAsunaprevir
ABT-450
DaclatasvirOmbitasvirLedipasvir
Objective - SVR
T (Years)
NR
SVR
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Fármacos anti-Vírus Influenza
Alvos terapêuticosÁcido nucleico: Ribavirina
Proteína M2: Amantadina, RimantadinaNeuraminidase: Zanamivir, Oseltamivir
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R = NH2 Amantadina
R = H Adamantano
R = RimantadinaN H 2
C H 3
Amantadina e Rimantadina
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Amantadina e Rimantadina Mecanismo de acção
Inibem a descapsidação do vírus devido ao bloqueio da proteína M2 que funciona como canal iónico.
A redução do influxo de H+ resulta na não libertação da NP
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Papel da Neuraminidase
Promove a libertação dos viriões
Previne a formação de agregados virais após a sua libertação da célula
Previne a inactivação viral por parte do muco Promove a entrada do vírus na células epiteliais do tracto respiratório
Induz a apoptose celular por activação do TGF β
Induz várias citocinas (IL-1, TNF, etc.)
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Inibidores da Neuraminidase
Galactose
Ácido N-acetilneuramínico (Ác. Siálico)
Neuraminidase
Inibidores da Neuraminidase
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Inibidores da Neuraminidase
Zanamivir
Intranasal
Oseltamivir
Oral
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Terapêutica do HIVInibidores da fusão do vírus com a célula
Inibidores da ligação aos co-receptores (CCR5)
Inibidores da transcriptase reversa
Inibidores da integrase viral
Inibidores da transcrição - inibidores da proteína Tat
Inibidores da maturação viral - Inibidores da protease viral
J Miguel Azevedo Pereira FFUL
Inibidores da transcriptase reversa
Análogos dos nucleósidos (NRTI)
Não análogos dos nucleósidos (NNRTI)
Análogos dos nucleótidos (NtRTI)
J Miguel Azevedo Pereira FFUL
Análogos dos nucleósidos (NRTI)
Fármaco Abreviatura Nome comercial
AZT+3TC CBV Combivir
Emtricitabina FTC Emtriva
Lamivudina 3TC Epivir
Zalcitabina KVX Kivexa
Zidovudina AZT Retrovir
AZT+3TC+ABC TZV Trizivir
FTC+TDF TVD Truvada
Didanosina ddI Videx
Stavudina d4T Zerit
Abacavir ABC Ziagen
J Miguel Azevedo Pereira FFUL
NRTI - Zidovudina
Desoxitimidina
J Miguel Azevedo Pereira FFUL
Fármaco Abreviatura Nome comercial
Tenofovir TDF Viread
Adefovir ADF Preveon; Hepsera
Inibidores da RT - NtRTI
J Miguel Azevedo Pereira FFUL
NtRTI - Tenofovir
Adenosina monofosfato
J Miguel Azevedo Pereira FFUL
Mecanismo de acção dos NRTI e NtRTI
J Miguel Azevedo Pereira FFUL
Inibidores da RT - NNRTI
Fármaco Abreviatura Nome comercial
Delavirdina DLV Rescriptor
Efavirenz EFV Sustiva
Nevirapina NVP Viramune
J Miguel Azevedo Pereira FFUL
NNRTI - DelavirdinaJ Miguel Azevedo Pereira
FFUL
Mecanismo de acção dos NNRTI
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w.H
IVw
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J Miguel Azevedo Pereira FFUL
Fármaco Abreviatura Nome comercial
Tipranavir TPV Aptivus
Amprenavir APV Agenerase
Indinavir IDV Crixivan
Saquinavir SQV InviraseLopinavir LPV Kaletra
Ritonavir RTV Norvir
Atazanavir ATV Reyataz
Fosamprenavir FPV TelzirNelfinavir NFV Viracept
Inibidores da Protease
Fármaco Abreviatura Nome comercial
Raltegravir RAL Isentress
Inibidores da Integrase
J Miguel Azevedo Pereira - FFUL
Inibidores da Protease
J Miguel Azevedo Pereira - FFUL
Mecanismo de acção da protease viral
gag
pol
env
poliproteína gag/pol poliproteína env
poliproteína gag
p17 p24 p9 p6 Protease RT Integrase SU TM
Genes
Proteínas precursoras
Proteínas finais
Proteasescelulares
Protease viral
J Miguel Azevedo Pereira - FFUL
Inibidor da Integrase - Raltegravir
J Miguel Azevedo Pereira FFUL
Fármaco Abreviatura Nome comercial
Enfuvirtida T-20 Fuzeon
Inibidores da fusão
Inibidores dos co-receptores
Fármaco Abreviatura Nome comercial
Maraviroc MRV Celsentri
J Miguel Azevedo Pereira FFUL
Inibidores do co-receptor CCR5
J Miguel Azevedo Pereira FFUL
Mecanismo de acção do inibidor de fusãoD
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l. 20
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Inibidor da Fusão - Enfuvirtide
J Miguel Azevedo Pereira - FFUL
Problemas na terapêutica anti-HIV
Variabilidade genética
Alta taxa de erro da DNA-polimerase RNA-dependente (RT)Alta taxa de replicação do HIV (109 partículas virais/dia)
Consequências:
Causas:
Mutações Variabilidade
Estirpes mais virulentas Fuga ao sistema imunológico
Estirpes resistentes
J Miguel Azevedo Pereira FFUL
Problemas na terapêutica anti-HIV
J Miguel Azevedo Pereira - FFUL
Problemas na terapêutica anti-HIV
Vírus latente vs. vírus em replicação
J Miguel Azevedo Pereira FFUL
J Miguel Azevedo-Pereira FFUL
How to induce replication of latent HIV
LETTERdoi:10.1038/nature11286
Administration of vorinostat disrupts HIV-1 latencyin patients on antiretroviral therapyN. M. Archin1, A. L. Liberty1, A. D. Kashuba1, S. K. Choudhary1, J. D. Kuruc1, A. M. Crooks1, D. C. Parker1, E. M. Anderson2,M. F. Kearney2, M. C. Strain3, D. D. Richman3, M. G. Hudgens1, R. J. Bosch4, J. M. Coffin2, J. J. Eron1, D. J. Hazuda5 & D. M. Margolis1
Despite antiretroviral therapy, proviral latency of humanimmunodeficiency virus type 1 (HIV-1) remains a principalobstacle to curing the infection1. Inducing the expression of latentgenomes within resting CD41 T cells is the primary strategy toclear this reservoir2,3. Although histone deacetylase inhibitors suchas suberoylanilide hydroxamic acid (also known as vorinostat,VOR) can disrupt HIV-1 latency in vitro4–6, the utility of thisapproach has never been directly proven in a translational clinicalstudy of HIV-infected patients. Here we isolated the circulatingresting CD41 T cells of patients in whom viraemia was fullysuppressed by antiretroviral therapy, and directly studied the effectof VOR on this latent reservoir. In each of eight patients, a singledose of VOR increased both biomarkers of cellular acetylation, andsimultaneously induced an increase in HIV RNA expression inresting CD41 cells (mean increase, 4.8-fold). This demonstratesthat a molecular mechanism known to enforce HIV latency canbe therapeutically targeted in humans, provides proof-of-conceptfor histone deacetylase inhibitors as a therapeutic class, and definesa precise approach to test novel strategies to attack and eradicatelatent HIV infection directly.
Among the many important aims of future HIV research is thedevelopment of therapies of finite duration capable of eradicatingHIV infection. The persistence of quiescent HIV infection within asmall population of long-lived CD41 T cells is currently a majorobstacle to this goal1. Histone deacetylases (HDACs) are recruited tothe HIV long terminal repeat (LTR) promoter, establishing one ofseveral restrictions that can limit LTR expression and maintain virallatency2,3. Deacetylated LTR chromatin seems to play a key contributoryrole in regulating HIV expression, and especially in maintaining proviralquiescence and latency. In vitro, HDAC inhibitors have been shown todisrupt latent proviral HIV infection in both cell culture models and exvivo assays using cells from HIV-1-infected patients. Althoughdisrupting latency has been proposed as part of a strategy to eradicateHIV infection, previous studies using the weak HDAC inhibitorvalproic acid did not consistently demonstrate a marked depletion ofresting cell infection7–11 in patients on antiretroviral therapy (ART).However, the effects measured in these studies are significantlydownstream of the molecular site of action of HDAC inhibitors, andthus the proximal pharmacodynamic measures of HDAC inhibitoractivity and HIV-1 expression were not evaluated. Here we show thatHDAC inhibitors disrupt the latency of proviral genomes withinresting CD41 T cells, establishing the first (to our knowledge) classof drugs that could lead to the eradication of HIV infection.
VOR is a potent HDAC inhibitor used to treat human malignancies.At clinically relevant concentrations, VOR inhibits the class I HDACsmost important for repression of HIV expression4,12; it also inducesLTR expression and virus production in vitro from the resting CD41 Tcells of HIV-positive patients on ART with levels of plasma HIV RNAbelow the detection limit (BDL)5,6,13. As the most proximal measure of
effect on latent infection is expression of HIV-1 RNA, we developed asensitive assay to enable a direct measurement of unspliced gag HIVRNA within the resting CD41 T cells of HIV-infected patients.The assay has a limit of detection of 1 copy per million restingCD41 T cells, and a limit of quantification of 10 copies per millionresting CD41 T cells.
To evaluate the effect of VOR on latent infection in vivo, HIV-infected patients receiving stable ART with plasma HIV-1 RNA,50 copies per ml for at least 6 months and a CD4 count .300ml21
were enrolled following informed consent. To demonstrate that it wasethical to expose patients to an experimental agent with potential riskin a study with no proven clinical benefit for the individual, we vali-dated the ability of this assay of HIV RNA within resting CD41 T cellsto measure HIV expression at baseline, and to detect up-regulation ofHIV expression in resting cells from each patient after physiologicalexposure to VOR.
Patients maintained suppressive ART, and purified populations ofresting CD41 T cells were obtained by continuous-flow leukapheresisand negative selection in an immunomagnetic column7. To establish abaseline, we measured the mean quantity of HIV-1 gag RNA in poolsof 1 million resting CD41 T cells immediately after their isolation frompatients. To measure validated biomarkers of VOR effect in peripheralblood mononuclear cells (PBMCs) of patients, we performed parallelassays of total cellular histone acetylation and measured histoneacetylation by chromatin immunoprecipitation (ChIP) at the humanp21 gene promoter, a gene known to upregulate chromatin acetylationafter VOR exposure14. Then to model the effect of a clinical dose ofVOR, multiple replicate pools of 1 million resting CD41 T cells wereincubated in complete media alone, with 335 nM VOR, or with 3mgphytohaemagglutinin (PHA) and 60 U interleukin-2 (IL-2) for 6 h.VOR conditions were selected to mimic the unbound drug exposureexpected after a single 400 mg dose of VOR in vivo5.
Validation assays were performed in resting CD41 T cells isolatedby leukapheresis from 16 patients with plasma HIV RNA BDL(Fig. 1a). In each patient a total of 48–72 million highly purified restingCD41 T cells were studied; that is, 12–48 million cells in each con-dition, depending on cell availability. In 9 patients following 6 h ofculture of 16–24 million cells without stimulation in media alone,HIV gag RNA was quantifiable at a mean level of 52 6 32 copies permillion cells. However, in the other 7 patients in whom 12–24 millioncells were studied (Fig. 1a), HIV RNA was not quantifiable at a limit of10 copies per million cells, although in all but 2 of these patients RNAwas detected but not quantifiable (.0 but ,10 copies per millioncells).
Following in vitro exposure to 335 nM VOR for 6 h, HIV RNAexpression was significantly upregulated in 8 of 9 patients in whomresting CD41 T cell HIV RNA was quantifiable without HDAC inhibitorexposure, and also in 3 of 7 patients in whom cell-associated HIV RNAwas ,10 copies per million cells before HDAC inhibitor exposure. In
1The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. 2HIV Drug Resistance Program, NCI, NIH, Frederick, Maryland 21702, USA. 3VA San Diego Healthcare System andUniversity of California San Diego, San Diego, California 92093, USA. 4Harvard School of Public Health, Boston, Massachusetts 02115, USA. 5Merck Research Laboratories, White Horse Junction,Pennsylvania 08889, USA.
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Macmillan Publishers Limited. All rights reserved©2012
Vorinostat - potent histone diacetylases (HDAC) inhibitor