Can we eradicate HIV? New therapeutic strategies towards a cure Laurence COLIN Laboratory of Molecular Virology University of Brussels Belgium The success story of HAART encountered solid barriers to virus eradication HAART: Highly Active Antiretroviral Therapy (statistics based on US citizens) - Toxicity of the drugs - Increase in the prevalence of several diseases (i.e. cardiovascular diseases,..) - Reduction in patient full life-time - Cost of the treatment - Development of resistant mutations by the virus - Unability to eradicate the virus from patients 1
The success story of HAART encountered solid barriers to virus eradication adapted from Dahl et al., Antivir. Res. 85, 286 (2010) The origins of persistent viremia 1. Anatomical sanctuaries central nervous system (CNS) gut-associated lymphoid tissue (galt) The existence of physical or functional barriers in viral sanctuaries, where drug penetration is highly limited, leads to a non-fully suppressive HAART therapy and to viral persistence 2
The origins of persistent viremia 2. Ongoing viral replication Low levels of ongoing viral replication prolong HIV persistence Presence of 2LTR circles with a short half-life would reflect recent rounds of infection Schacker, Nat. Med 16, 373-4 (2010) HAART is not 100% suppressive BUT intensification therapies (i.e. with Raltegravir) did not succeed The origins of persistent viremia 3. Latently-infected T cells Naïve +Ag HAART viral cytopatic effects host immune response Activated -Ag -Ag Resting memory +Ag +Ag Pre-integration Latency Activated 3
Pre-integration blocks APOBEC3G TRIM5alpha J.Cohen Science Pre-integration latency does not seem to be of clinical relevance The origins of persistent viremia 3. Latently-infected T cells Naïve +Ag Activated -Ag -Ag -Ag Resting memory +Ag +Ag +Ag Post-integration Latency Activated 4
Current strategies to achieve a cure? decrease the size of latent reservoirs to a level sufficient to allow control by the host immune system 1. latently-infected cells can be eliminated Long-Term Control of HIV by CCR5 Delta32/Delta32 Stem-CellTransplantation Gero Hütter, M.D., Daniel Nowak, M.D., Maximilian Mossner, B.S., Susanne Ganepola, M.D., Arne Müßig, M.D., Kristina Allers, Ph.D., Thomas Schneider, M.D., Ph.D., Jörg Hofmann, Ph.D., Claudia Kücherer, M.D., Olga Blau, M.D., Igor W. Blau, M.D., Wolf K. Hofmann, M.D., and Eckhard Thiel, M.D. N Engl J Med 2009; 360:692-698 2. The host immune system should be able to control the infection standard elite controllers O Connell et al., Trends Pharmacol Sci. 2009 Dec;30(12):631-7. Current strategies to achieve a cure? decrease the size of latent reservoirs to a level sufficient to allow control by the host immune system Two approaches: A. Turn on resting T cells into activated T cells B. Turn on HIV-1 gene expression in latently-infected cells.while maintaining or intensifying HAART in order to prevent new spreading infection by neo-synthesized virions. 5
A. Turn on resting T cells into activated T cells IAT: immune activation therapy Adapted from Geeraert et al., Annu Rev Med. 2008;59:487-501. These trials showed a decrease of s containing replication competent proviruses but a reemergence of plasma viremia was systematically observed in the two to three weeks following treatment interruption. B. Turn on HIV-1 gene expression in latent reservoirs HIV-1 post-integration latency is a multifactorial phenomenon: 1. The site of integration in the host cell genome 2. The absence of inducible cellular transcription factors 4. The epigenetic control of the promoter region 5. The absence of Tat or Tat-associated factors 6. The RNA interference pathway 6
1. The site of integration into the host cell genome genome LEDGF targets the PIC to actively transcribed genes Transcriptional interference Suzuki and Craigie, Nature Reviews Microbiology 5, 187-196 (March 2007). 2. The absence of inducible cellular transcription factors ACTIVATION (PKC agonists) Adapted from Colin and Van Lint, Retrovirology 2009; 6: 111.. 7
2. The absence of inducible cellular transcription factors Prostratine (12-deoxyphorbol 13-acetate) DPP (12-deoxyphorbol 13-phenylacetate) Bryostatin (especially Bryostatin-1) Prostratin PKC agonists are interesting compounds since they activate viral transcription in latently-infected cells and prevent new infections by decreasing the expression of the CD4 receptor necessary for HIV- 1 entry into the cells Double-stranded DNA Heterochromatin Histones Nucleosome Euchromatin Chromosome 8
1. Histone acetylation ACTIVATION (HDAC inhibitors) Adapted from Colin and Van Lint, Retrovirology 2009; 6: 111.. 1. Histone acetylation Name Family HDAC inhibition Clinical trials Na butyrate Na phenylbutyrate Valproic acid aliphatic aliphatic aliphatic Colon cancer, Rectal cancer, Cystic fibrosis, Myeloid leukemia, Lymphoma Adult acute myeloid leukemia, Lymphocytic leukemia MS-275 Sirtinol benzamide benzamide III Leukemia, Myeloid disease, Lymphoma Apicidin Depudecin cyclic tetrapeptid cyclic tetrapeptid APHA com. 8 CBHA M344 hydroxamic hydroxamic hydroxamic Oxamflatin hydroxamic SAHA hydroxamic Acute T-cell Lymphoma SBHA hydroxamic 9
2. Histone methylation ACTIVATION (HMT inhibitors) Adapted from Colin and Van Lint, Retrovirology 2009; 6: 111.. 2. Histone methylation Imai et al., J Biol Chem. 2010 May 28;285(22):16538-45. Drug development of less toxic inhibitors of histone methyltransferases is needed to further assess their potential use in reactivation of HIV-1 from latency 10
3. DNA methylation TFs Promoter Promoter Kauder et al., PLoS Pathog. 2009 June; 5(6): e1000495.. 3. DNA methylation - Nucleotide analogs: - DNA methyltransferase inhibitors: (decitabine) procaine, procainamide, RG108, 11
4. The absence of Tat and Tat-associated factors P-TEFb sequestration of P-TEFb in the cytoplasm by HEXIM-1 and the 7SK snrna is reversible HMBA (Hexamethylene bisacetamide) 5. The RNA interference pathway A better understanding of the complex interplay between HIV and the RNA interference pathway could be exploited to reactivate HIV from latency. 12
Multiple targets to reactivate HIV-1 latency Adapted from Colin and Van Lint, Retrovirology 2009; 6: 111.. Today, one of the most promising strategy to target latent reservoirs resides in combinations of several families of compounds to force HIV-1 gene expression simultaneously at different levels, while maintaining HAART to prevent new infections. Combination therapies: a proof of concept study relative p24 antigen level 3000 2500 2000 1500 1000 500 0 1 20 J-Lat 15.4 2 113 4 189 110 639 165 2331 4 350 mock Pro VPA Pro+VPA SAHA Pro+SAHA TSA Pro+TSA NaBut Pro+NaBut MS-275 Pro+MS-275 Synergistic activation Reuse et al., PLoS One. 2009 Jun 30;4(6):e6093.. Treatments Patients Pro VPA Pro+VPA SAHA Pro+SAHA X1 + - +* / / X2 + - +* / / X3 - - - - +* X4 + + +* + +* X5 + - +* / / X6 + - +* / / X7 - - - - +* X8 - - - - +* X9 + - +* - +* X10 - - +* - +* X11 + + +* - +* X12 - - +* - +* X13 - - +* - +* X14 + + +* - +* X15 - / / - +* X16 + / / - +* X17 - / / - +* X18 + - + / / X19 + - + / / X20 + - + - + X21 + - + / / X22 + - + - + X23 + - + + + X24 + / / + + X25 + / / - + Percentage of reactivation 68% 15% 85% 17% 100% 13
remaining challenges In the laboratories 1. Better in vitro models and animal models 2. Better sensitive and non invasive ways to quantify HIV-1 latent reservoirs (notably in the galt) 3. Drug development to increase specificity and decrease toxic effects 4. Better understanding of immune response to HIV 5. Better understanding of mechanisms leading to latency Against the epidemics 1. Universal access to HAART to strangle the epidemics 2. Clinical trials aiming at reactivating HIV-1 latent reservoirs remain difficult tasks in patients who already enjoy a good quality of life thanks to HAART but such reactivation strategies have been well characterized in laboratories. Next step to virus eradication is thus their evaluation in patients. University of Brussels, Belgium Insitute for Molecular Medicine and Biology Laboratory of Molecular Virology Director of research Carine Van Lint Lab members Sophie Bouchat Christelle Cardona Jean-Stéphane Gatot Allan Guiguen Sophie Reuse Gwenaëlle Robette BenoîtVan Driessche Caroline Vanhulle Thanks for your attention 14