Differential Detection of M184V/I Between Plasma Historical HIV Genotypes and Proviral DNA from PBMCs N Margot, R Ram, IR McNicholl, R Haubrich, C Callebaut Gilead Sciences, Inc., Foster City, CA, USA 10th IAS Conference on HIV Science (IAS 2019) 21-24 July 2019 Mexico City, Mexico Poster MOPEB249

Background HIV resistance testing/monitoring is an integral part of HIV treatment¹ Plasma resistance testing is used to generate the sequence and drug susceptibility phenotype of the circulating virus Plasma resistance testing prior to antiretroviral (ARV) therapy initiation or in situation of virologic failure is conducted to help physicians select the appropriate regimen for the patient (Figure 1) Plasma resistance testing requires detectable virus (HIV-1 RNA >50 copies/mL) HIV-1 RNA >500 copies/mL required for most commercial assays Cannot be conducted for patients with undetectable viral load (<50 copies/mL) seeking to switch treatment for tolerability or simplification reasons Resistance to switch regimen could exist due to past virologic failure or transmitted drug resistance2, 3 HIV DNA resistance testing that evaluates resistance mutations in PBMC-integrated HIV DNA may be used instead Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living with HIV. Department of Health and Human Services, 2018. Miller et al, Antiviral Therapy, 2012. Margot et al, the Journal of Infectious Diseases, 2017. Margot, IAS, 2019, Presentation # MOPEB249

Figure 1: HIV Resistance Testing and Antiretroviral Therapy No Treatment Treatment A Treatment B Treatment C Treatment Switch Plasma Resistance Testing - RAM? Plasma Resistance Testing not Possible (VL<50 c/mL) HIV-1 RNA (copies/mL) 8 RAM: resistance-associated mutation; VL: HIV-1 RNA viral load Margot, IAS, 2019, Presentation # MOPEB249

Methods Study 292-1824 is an ongoing switch study in patients with historical M184V/I resistance mutation (Figure 2) HIV-1 RNA <50 copies/mL for at least 3 months prior to screening All screened patients (n=84) had historical plasma resistance record showing the presence of M184V/I Records from commercial sources and local laboratories HIV DNA resistance analysis assay was conducted for all patients to confirm the absence of exclusionary mutations (PI-R, INSTI-R, NRTI-R) (GenoSure Archive, Monogram Biosciences) Detection of mutations from historical records and HIV DNA analysis were compared Margot, IAS, 2019, Presentation # MOPEB249

Figure 2: Study 292-1824 Switch Study in Patients with Historical Detection of M184V/I HIV-1-infected Adults Switch from 2 NRTIs + 3rd agent  E/C/F/TAF HIV-1 RNA < 50 c/mL Historical Genotype showing M184V/I Part 1: M184V/I only Part 2: M184V/I ±0-2 TAMs No exclusionary mutation in HIV DNA analysis E/C/F/TAF QD N = 63* 12 weeks Primary Endpointa 24 weeks Secondary Endpointb 48 weeks (a) Perez-Valero IDRW, 2017 (b) Perez-Valero WorldAIDS, 2018 (*) Enrolled patients 100% Suppression using Pure Virologic Failure E/C/F/TAF: single-tablet regimen containing elvitegravir (E), cobicistat (C), emtricitabine (FTC, F), tenofovir alafenamide (TAF) Margot, IAS, 2019, Presentation # MOPEB249

Table 1: Detection of M184V or I (N=84) Historical HIV RNA report vs Table 1: Detection of M184V or I (N=84) Historical HIV RNA report vs. HIV DNA report Paired historical & archival data available for 84 screened patients HIV DNA: M184V/I mutation detected in only 48% patients Margot, IAS, 2019, Presentation # MOPEB249

Figure 3: Presence of M184V and M184I Historical HIV RNA report vs Figure 3: Presence of M184V and M184I Historical HIV RNA report vs. HIV DNA report M184V: detected with HIV DNA in 48% patients M184I: detected with HIV DNA in 33% patients Margot, IAS, 2019, Presentation # MOPEB249

Figure 4: Impact of Sample Timing in M184V/I Detection Time: Historical  Archive ART H A Time: ART Start  Archive ART H A 30 10 1 0.3 M184V/I Detected Not Detected Time (years) Time (years) M184V/I Detected Not Detected 30 10 1 0.3 Median: 7.1 7.6 p=0.43* Median: 17.5 15.1 p=0.62* ART: antiretroviral therapy; H: historical HIV RNA genotypic report (plasma); A: Archival HIV DNA genotypic report (PBMCs); (*) Mann Whitney test Differential detection not due to time between HIV DNA analysis and historical HIV RNA analysis or time on ART Margot, IAS, 2019, Presentation # MOPEB249

Figure 5: Impact of Baseline ART Regimen in M184V/I Detection Differential detection not associated with baseline regimen ART: antiretroviral therapy; INSTI: integrase strand transfer inhibitor; NNRTI: non-nucleoside reverse transcriptase inhibitor; PI: protease inhibitor Margot, IAS, 2019, Presentation # MOPEB249

Figure 6: Impact of Baseline CD4/HIV-1 RNA in M184V/I Detection Differential detection not associated with Baseline CD4 count or viral load TND: target not detected; VL: Viral load; (*) Mann Whitney test Margot, IAS, 2019, Presentation # MOPEB249

Conclusions In subjects with documented M184V/I on historical genotype (HIV RNA assay): M184V not detected in 52% with HIV DNA assay M184I not detected in 67% with HIV DNA assay (possibly due to A3G filtering) Difference in detection of M184V/I between the 2 assays not associated with: Time between historical HIV RNA testing and HIV DNA testing Time on ART Prior treatment regimen Baseline CD4 count HIV-1 RNA detection (TND, <20, <50) Not detecting M184V/I with the HIV DNA assay may have potential clinical consequences when switching patients to 2-drug treatment containing FTC or 3TC, as the presence of M184V/I confers high-level resistance to FTC and 3TC Margot, IAS, 2019, Presentation # MOPEB249

Acknowledgements 1824 Study Investigators and Staff V Abril López de Medrano, M Andreoni, JR Arribas Lopez, L Bernard, M Bickel, M Castaño Carracedo, D Coulston, E DeJesus, A Di Biagio, G Di Perri, C Duvivier, S Esser, J Gallant, M Galli, D Hagins, E Lazaro, A Lazzarin JM Llibre, J Mallolas, A Mills, C Miralles Álvarez, JM Molina, O Osiyemi, I Perez-Valero, I Poizot-Martin, T Prazuck, D Prelutsky, P Pugliese, F Pulido, F Raffi, M Ramgopal, G Richmond, D Salmon-Ceron, J Schattenberg, P Sellier, P Shalit, HJ Stellbrink 1824 Study Participants and their Family E/C/F/TAF Project Team Margot, IAS, 2019, Presentation # MOPEB249