1. 2014 “Towards an HIV Cure” symposium Melbourne The Immune Checkpoints PD-1, LAG-3 and TIGIT are Biomarkers of HIV Infected Cells During ART and Identify Distinct Cellular Reservoirs Remi Fromentin, Wendy Bakeman, Mariam B Lawani, Gabriela Khoury, Elizabeth Sinclair, Frederick M. Hecht, Steven G. Deeks, Sharon R. Lewin, Jean-Pierre Routy, Rafick P. Sékaly, Nicolas Chomont

2. Biomarkers of latently infected cells during ART Identifying biomarkers of latently infected cells is of primary importance to specifically target and eliminate the persistent reservoir Approach: Combining the “Where” with the “How” Where: HIV persists in discrete subsets of cells during ART How: Mechanisms driving the establishment and persistence of the HIV reservoir Biomarkers of latently infected cells could be: - surrogate markers of higher susceptibility to HIV infection - markers of persistence providing selective advantages (latency maintenance, immune escape, replenishment)

3. Why immune checkpoints (ICs) could be biomarkers for HIV persistence during ART ? Chen L, Nat Rev Imm. 2013 ICs, negative regulators of T cell activation, regulate T cell proliferation and cytokine production. Several of these molecules are associated with T cell dysfunction in chronic HIV infection (PD-1, CTLA-4, TIM-3, CD160). (Trautmann et al, NatMed 2006; Kaufmann et al, NatImm 2007; Jones et al, JEM 2008, Peretz el al, PLoSPath 2012) Immune dysregulations persist during ART (residual immune activation, incomplete CD4 T cell restoration, T cell dysfunction). (Hatano et al, JID 2012; Kelley et al, CID 2009)

4. Hypothesis By inhibiting T cell activation, negative regulators (Immune Checkpoints, ICs) may actively maintain viral latency and identify reservoir cells during ART. ICs silence HIV Inhibitory signals silencing HIV APC Activated/Productively infected CD4 T cell ICs Persistent/Latently infected CD4 T cell + - + - ICs ICs = selective advantage for latently infected cells AB ART

5. Association between the expression of ICs and virological markers of HIV persistence Study population: 48 HIV infected subjects virally suppressed for at least 3 years with CD4>350 c/µL Methods: - Multiparametric flow cytometry analysis of the expression of 8 ICBs (PD- 1, LAG-3, TIGIT, CTLA-4, BTLA, CD160, 2B4, TIM-3) in PBMCs - ultrasensitive qPCRs to measure the frequency of CD4 T cells harboring virological markers of HIV persistence The frequency of CD4 T cells expressing PD-1, LAG-3 and TIGIT are positively correlated with the frequency of CD4 T cells harboring integrated HIV DNA during ART.

6. PD-1 identifies T CM and T TM CD4 T cells enriched in integrated HIV DNA T CM T TM T EM The frequency of cells harboring integrated HIV DNA is significantly higher in PD-1 expressing T CM and T TM when compared to their PD-1 negative counterparts. Differentiation AB

7. LAG-3 identifies T CM and T TM CD4 T cells enriched in integrated HIV DNA T CM T TM T EM The frequency of cells harboring integrated HIV DNA is significantly higher in LAG-3 expressing T CM and T TM when compared to their LAG-3 negative counterparts. Differentiation AB

8. TIGIT identifies T EM CD4 T cells enriched in integrated HIV DNA T CM T TM T EM The frequency of cells harboring integrated HIV DNA is significantly higher in TIGIT expressing T EM when compared to their TIGIT negative counterparts. Differentiation AB

9. Can we further enrich in the reservoir by combining multiple ICs? Means +/-SD from 5 subjects AB Memory CD4 T cells expressing multiple ICs are highly enriched for integrated HIV DNA

10. Is the virus carried by latently infected cells expressing ICs functional ? A B Principle of “Tat/Rev Induced Limiting Dilution Assay” (TILDA) Sorted CD4 + T cells PMA/Ionomycin (12h) 18000 cells/well 9000 cells/well 3000 cells/well 1000 cells/well Nested RT-PCR For msHIV RNA (24+40 cycles) Maximum likelihood method Frequency of cells with inducible msHIV RNA Memory CD4 T cells expressing LAG-3 and/or PD-1 and/or TIGIT are highly enriched for inducible HIV latently infected cells.

11. Conclusions Altogether, our data suggest that blocking ICs may reactivate HIV from latency and paves the way for the development of novel strategies to cure HIV infection. Biomarkers CMTMEM PD-1 LAG-3 TIGIT 1. 2. Enrichment for HIV infected cells

12. Acknowledgements VGTI Florida Wendy Bakeman Amanda McNulty Mariam B. Lawani Rafick-Pierre Sekaly Nicolas Chomont UCSF Steven Deeks Hiroyu Hatano Rick Hecht Rebecca Hoh Elisabeth Sinclair Lorrie Epling Burnet Institute Gabriela Khoury Sharon R. Lewin McGill University Jean-Pierre Routy Merck Daria Hazuda Mike Miller Richard J.O. Barnard Dan Gorman The study participants