Viral load e Profilassi Post Esposizione

Transcription

1 Predisposizione delle Linee guida di profilassi post-esposizione 2013: punti critici ed indicazioni per l aggiornamento delle raccomandazioni nazionali. Viral load e Profilassi Post Esposizione Alessandra Amendola Istituto Nationale per le Malattie Infettive Lazzaro Spallanzani

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3 La Profilassi post-esposizione 1. 2.

4 HIV Transmission McMichael AJ, NATURE ReVIewS, 2012 Immunology... Le evidenze disponibili indicano che la PPE può essere tanto più efficace quanto prima iniziata; perde di efficacia quando siano trascore più di 48 ore dall esposizione, e deve essere protratta per almeno 4 settimane... (Linee guida italiane)

5 Factors influencing HIV transmission Type of exposure Plasma HIV RNA concentration Genital HIV RNA concentration Occurrence of STI Pregnancy Clinical stage of HIV disease EACS, 2012 ARV treatments HIV treatment resistance

6 High HIV viral loads in peripheral blood are associated with an increased rate of HIV transmission 2000 * HIV rate of transmission: a dose-response effect Test: Amplicor HIV-1 Monitor 1.5 assay, Roche Molecular Systems LOD: 400 cp/ml LOD: cp/ml [Review, Attia S, 2009]

7 P <.001 HPTN 052: HIV Transmission reduced by 96% in serodiscordant couples with early ART Total HIV-1 Transmission Events: 39 (4 in immediate arm and 35 in delayed arm; P <.0001) Linked Transmissions: 28 Unlinked or TBD Transmissions: 11 Delayed Arm: 27 Immediate Arm: 1 (96%) Single transmission in patient in immediate HAART arm believed to have occurred close to time therapy began and prior to suppression of genital tract HIV.

8 Guidelines for post-exposure prophylaxis (PEP) in both occupational and non-occupational settings

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10 . La maggior parte delle esposizioni non determina la trasmissione di HIV ed il rischio in seguito ad una singola esposizione è in media dello %; alcune circostanze o fattori determinano un aumentato rischio di trasmissione, altre lo riducono : per es. la probabilità di trasmissione correla significativamente con la concentrazione di HIV nel materiale cui ci si espone, sia esso sangue o secrezioni genitali

11 High genital HIV-1 viral loads are associated with an increased rate of HIV transmission Genital HIV RNA concentration: Zhang H, NEJM 1998 Endocervical swabs : HIV RNA detected: 1081/ % HIV RNA quantity (median): 3.20 log 10 cp/ml ( ) HIV RNA quantity (median) among samples with detectable HIV-RNA : (n=1081) 3.74 log 10 cp/ml ( ) Semen: HIV RNA detected: 404/ % HIV RNA quantity (median) 2.57 log 10 cp/ml ( ) HIV RNA quantity (median) among samples with detectable HIV-RNA (n=404) 3.44 log 10 cp/ml ( ) Quayle A Baeten 2011

12 The concentration of HIV-1 in semen and in the genital and rectal compartments is likely to be the most important determinant of sexual HIV transmission. COBAS Ampliprep/COBASTaqMan HIV-1 v 1.0 LOQ: 40 cp/ml HIV-1 RNA for blood plasma, 240 cp/ml for seminal plsma and swab for endocervical samples

13 Genital and plasma viral load correlation Good correlation between peripheral-blood viral load and viral load in seminal plasma and cervical secretions Correlations ranged between 0.07 and 0.64 Viral loads in genital secretions appear to fall in concert with the declines in peripheral-blood viral load after combination therapy... However, despite reductions in peripheral-blood and seminal plasma viral load, integrated viral DNA is still present in seminal cells, and virus can be recovered in-vitro...

14 Persistence of Residual Viremia (RV) during ART in 60-80% of patients RV (~ 3cp/ml)

15 Evidence of persistent RV in HAART-suppressed individuals Palmer et al. JCM 2003; Maldarelli et al, PLoS Pathog 2007 RV extent 1-5 cp/ml RV extent cp/ml Hatano, AIDS 2010

16 RV may depend on drugs NVP EFV 19% 81% VL <1 copy VL >1 copy 64% 36% VL <1 copy VL >1 copy

17 Raltegravir intensification studies: no reduction in low-level RV P = N patients: 9 LOD: 0.2 copies/ml

18 Set point of RV: factors associated with lower levels of VR Il livello di VR correla con la carica virale pre-terapia e con la durata della terapia efficace.

19 RV in elite controllers

20 Origin of RV Ongoing virus replication in sanctuary cellular or body compartments due to poor drug penetration or activity Virus reactivation in latently infected cells in response to stochastic antigenic stimulation, with presence of HAART ensuring that new cells cannot be productively infected Shen, J Allergy Clin Immunol 2008

21 RV in the way of viral eradication Buzon et al. Llibre JM, Buzon MJ et al. Antivir Ther Sep 28 The accumulation of 2-LTR occurs after intensification of therapy with raltegravir; then a relatively large number of cells are undergoing active infection

22 RV in the way of viral eradication

23 RV in the way of viral eradication

24 Virus transmission and ART Fais S AIDS 1995

25 Persistent HIV RNA shedding during ART

26 Persistent HIV RNA shedding during ART Test: NucliSens HIV-1 QT LOD: 80 cp/ml plasma; 3300 cp/ml genital specimens AIDS 2010

27 TEST: Home-made methods. LOD: For HIV-1 RNA, 80 copies/ml in seminal or blood plasma, and 80 copies/sample in semen cells. For HIV-1 DNA, 100 copies per sample in semen cells). HIV transmission during ART

28 Transmission from person with undetectable genital HIV RNA 7 female-to-male and 4 male-tofemale Blood plasma HIV RNA: median 4.4 log 10 cp/ml (range ) Genital HIV RNA: undetectable COBAS Ampliprep/COBASTaqMan HIV-1 v 1.0 LOQ HIV-1 RNA : 40 cp/ml for blood plasma; 240 cp/ml seminal plsma and swab for endocervical samples

29 Test diagnostici per la misura della carica virale di HIV

30 Dynamic ranges of commercial assays for HIV-1 RNA quantification LOD (cp/ml) Real time PCR Abbott Molecular Abbott RealTime HIV 40 biomerieux NucliSENS EasyQ v Roche Molecular Systems (Amplicor Monitor HIV v1.5) Cobas TaqMan HIV v1.0 Cobas TaqMan HIV v Siemens Healthcare Versant 3.0 bdna Versant HIV RNA v1.0 kpcr 37 * FDA approved tests cp/ml HIV RNA copies/ml

31 HIV-1 RNA quantification by a real-time PCR-based assay: (i.e. Abbott Real-time HIV-1: LOD = 40 cp/ml) Results Interpretation 1. Not-detected Target not detected 2. < 40 cp/ml Target detected, but not quantifiable cp/ml 4. > cp/ml

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33 Good correlation between the assays across their linear range Gruppo M, sottotipo B Roche TaqMan v2.0 vs Abbott Real-Time HIV-1 Sire JM et al. 2011

34 Log 10 cp/ml 1 st International Reference Panel HIV-1 RNA genotypes (NIBSC code 01/466) 4,00 3,50 3,00 2,50 2,00 1,50 1,00 0,50 0,00 Subtypes A B C D AE F G AA GH N O bdna 0 3,06 3,20 3,07 3,49 3,33 3,47 3,25 3,58 2,62 0,00 kpcr (real-time) 0 3,23 3,08 2,82 3,44 3,44 3,45 3,24 3,56 0,00 2,66 EasyQ (real-time) 0 3,26 3,18 2,89 3,59 2, , Abbott (real-time) 0 3,44 3,25 3,21 3,67 3,68 3,67 3,65 3,85 2,74 2,69 bdna data from Holmes Het al., Development of the 1st International Reference Panel for HIV-1. Journal of Virological Methods, 2008 Amendola A, unpublished

35 1 st International Reference Panel HIV-1 RNA genotypes (NIBSC code 01/466)

36 Influence of genetic diversity Siemens Versant kpcr 1.0 vs Roche TaqMan v2.0

37 Influence of genetic diversity Roche TaqMan v2.0 vs Abbott Real-Time HIV-1 B CRF02

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39 Low levels of viremia Although the results with different assays tend to have acceptable correlation at relatively high HIV-1 RNA levels, inter- and intra- assay variability may be significant around the lower quantification limits.

40 HIV RNA (log 10 cp/ml) by Real-time PCR Measured (log 10 IU/ml) Linearity/Accuracy/Precision at low VL values 6 5 Roche TaqMan v1.0 HIV-1 RNA test panel (BBI Diagnostics) y=0.959x r= ( 0.75% 5 4 Abbott Real-time HIV 2nd HIV-1 RNA International Standard WHO 97/650 y = 0,8936x + 0,3864 R² = 0,9982 CV:0.68% % 3 CV: 2.5% CV: 1.6% % 12.4% 13.8% 6.3% 2 1 CV: 9,7% CV: 1.3% CV: 7.8% CV: 3.3% Expected HIV RNA (log 10 cp/ml) Expected HIV RNA (log 10 IU/ml) Occasional, small increases above the background HIV-1 RNA may be not clinically relevant or may even reflect falsepositive results associated with diagnostic system errors Imprecision inherent to the assay may be the cause of fluctuations in HIV-1 RNA measurements near the assay s lower limit. Accuracy is essential to distinguish truly significant clinical changes in the viral load from background noise ( artifacts ) and intermittent episodes of detectable viremia ( blips ). Amendola et al, CID 2009 and Microbiologia Medica 2010

41 Poor concordance at the clinically critical lower level of quantification Abbott Real-Time HIV-1 vs Roche TaqMan v clinical samples with >40 VL cp/ml <1000 by Abbott Real-Time HIV Correlation: Amendola A, unpublished

42 Poor concordance at the clinically critical lower level of quantification Agreement at the cut-off of 20 and 40 cp/ml: 0.671

43 Poor concordance at the clinically critical lower level of quantification

44 Poor concordance at the clinically critical lower level of quantification HIV-1 RNA Working Reagent for NAT assays (NIBSC) below 200cp/ml 16 cp/ml, 32 cp/ml, 64 cp/ml, 128 cp/ml Abbott Real-Time HIV-1 Roche TaqMan v2.0 D= log 10 cp/ml D= log 10 cp/ml (3.45 fold) Amendola A, Poster ECCMID 2012 and submitted

45 Viral blips Intermittent episodes of detectable low-level viral rebound proceeded and followed by undetectable viremia without any change in therapy (Lee, JAC 2006). Causes of blips Artefactual measurements: 1. Random variation around sensitivity limit (Nettles RE, JAMA, 2005) 2. Improper sample processing (Bakken Kran, JCM 2009) True viremia: 1. Adherence issues (Podsadecki, JID, 2007) 2. Development of resistance (Geretti, CID, 2012) 3. Virus release from latent reservoirs: activation of latently infected cells (antigen-driven, e.g. vaccination or opportunistic infections) (Palmer, JIM, 2012)

46 Last updated March 2012 Optimal viral suppression: viral load persistently below the level of detection (<20 75 copies/ml, depending on the assay used). Minimal change in viral load statistically significant (2 standard deviations) 0.5 log10 copies/ml change. Low-level positive viral load results (typically <200 copies/ml) commonly reported with some viral load assays. No definitive evidence that patients with <200 copies/ml are at increased risk for virologic failure For the purpose of patient monitoring, the Panel defines virologic failure as a confirmed viral load >200 copies/ml, which eliminates most cases of viremia caused by isolated blips or assay variability.

47 Viral blips JID 2012:205 (15 April) Retrospective, observational cohort study using information collected through the Canadian Observational Cohort (CANOC) collaboration (8 HIV cohort studies from Ontario, Quebec, and British Columbia); 3550 participants, median FU: 2.7 years. 756 of the 3550 participants (21%) had >1 blips during the study period. a median of 11 times per patient Virologic rebound defined as either an HIV-1 RNA value 50 copies/ml at 2 consecutive visits at least 30 days apart or an HIV- 1 RNA value >1000 copies/ml. 874 (85%) of the virologic blips were between 50 and 199 cp/ml 71 (7%) were between copies/ml, 38 (4%) were between copies/ml, 40 (4%) were between copies/ml. the Amplicor assay was associated with a lower blip rate than branched DNA blips of copies/ml were associated with virologic rebound (HR, 2.70; P.002), whereas blips of were not.

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49 Gli attuali test per HIV RNA sono validati per l uso con plasma umano raccolto in anticoagulante EDTA. L uso con altri tipi di campioni per lo svolgimento del test può generare risultati non accurati e difficilmente paragonabili. bdna e COBAS Amplicor HIV-1 Monitor 1.5 LOD: 50 cp/ml entrambi Abbott assay

50 No standardized assys for semen samples

51 E POSSIBILE Prevenzione primaria Terapia antiretrovirale E UTILE [Cura] Maggior accesso alla terapia in tempi brevi Maggior accesso ai test diagnostici Maggior utilizzo di test sensibili (Ag p24, HIV RNA US) E AUSPICABILE Incremento della sensibilità dei test diagnostici Riduzione dei tempi di risposta Adattamento e standardizzazione di test diagnostici per il dosaggio dell RNA nei campioni genitali

52 GRAZIE