CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

of BIC, E92Q added G140E while Q148R, N155H, and R263K did not add any substitutions at positions associated with INSTI-R. WT and IN mutants, including R263K, developed M184V/I substitutions in RT under FTC pressure. All IN mutants showed higher phenotypic resistance to RAL and EVG than to DTG and BIC. Conclusion: DTG and BIC selected similar substitutions in WT IN with little to no phenotypic resistance to either drug. Development of additional resistance substitutions was infrequent in selections starting with mutant IN. These results support potential utility and investigation of BIC (in addition to DTG) in patients with preexisting INSTI-R.

in subtype B pNL4.3 context and of 1.1, 1.9 and 2.4 for RAL, DTG and EVG, respectively in CRF02_AG context. Conclusion: Among this large set of IN sequences, overall prevalence of E157Q was 2.7%with heterogeneity among HIV-1 subtypes. Focusing on ARV-naïve patients receiving a first-line INI-based regimen, two out of the five patients receiving EVG did not reach undetectability at W24, despite baseline VL below 5 log c/mL. Phenotypic analyses showed that the highest E157Q fold-change was observed for EVG in CRF02_AG context, borderline to the 2.5 Phenosense© cut-off. These findings highlight the need to better understand the role of E157Q polymorphism and of potential associated genotypic determinants

548 CHARACTERIZATION OF THE DOLUTEGRAVIR MONOTHERAPY-ACQUIRED S230R RESISTANCE MUTATION Hanh T. Pham 1 , Ingeborg Wijting 2 , Lydia Labrie 1 , Said Hassounah 1 , Ineke van der Ende 2 , Bluma G. Brenner 1 , Bonnie Spira 1 , Charles Boucher 2 , Bart Rijnders 2 , Jeroen J. van Kampen 2 , Thibault Mesplede 1 , Mark A. Wainberg 1 1 McGill University, Montreal, QC, Canada, 2 Erasmus University Medical Center, Rotterdam, Netherlands Background: Dolutegravir (DTG) is a potent and well tolerated integrase strand-transfer inhibitor (INSTI) with a high barrier to resistance, which makes it a suitable candidate for antiretroviral maintenance monotherapy and simplified regimens. Here, we report the emergence of a S230R substitution in two patients who experienced virological failure after switching to DTG monotherapy from triple therapy and have characterized the effects of S230R on integrase (IN) enzyme activity, viral infectivity and drug resistance. Methods: IN-resistance associated mutations were evaluated by sequencing both prior to and at the time of virologic failure. The pET15b-IN overexpression and pNL4.3 proviral vectors containing S230R were generated by site-directed mutagenesis. Biochemical strand-transfer and tissue culture assays were performed to characterize enzyme activity, viral infectivity and to measure resistance to DTG and other INSTIs. Results: The first case of S230R was found in the context of the DOMONO study (NCT02401828) in a patient who experienced virologic failure at week 30 (HIV-1 RNA was 1570 copies/mL). The patient had a CD4 nadir of 330 cells/mm 3 and had been virologically suppressed on EFV/TDF/FTC for 25 months before switching to DTG 50 mg once daily. A second case involved a patient who had been virologically suppressed on DTG/ABC/3TC for 8 months before switching to DTG monotherapy. Viral load (VL) remained <20 copies/mL but increased to 700 copies/mL with the presence of S230R in IN at week 29. The results of cell-free assays showed that, compared to the WT-IN (Km= 8.8 ± 0.95), the S230R-IN had a modest 2.22-fold increase in Km (19.9 ± 2.3). In the presence of DTG, yielding a 2.6- fold decrease in DTG susceptibility. The infectivity of S230R virus was also impaired by about 1.26-fold compared to WT. The relevance of the S230R substitution was confirmed in a recent study, where DTG monotherapy failed to durably suppress HIV viremia in humanized mice. Conclusion: In conclusion, virological failure involving DTG monotherapy can occur due to replication of a virus containing a novel S230R substitution that confers modest-level resistance to DTG and other INSTIs. 549 IN VITRO SELECTED RESISTANCE TO NEW INTEGRASE INHIBITORS BY B & NON-B SUBTYPE VIRUSES Bluma G. Brenner , Maureen Oliveira, Ruxandra-Ilinca Ibanescu, Bonnie Spira, Background: The integrase strand transfer inhibitors (INSTIs) bictegravir (BIC), dolutegravir (DTG), and cabotegravir (CAB) have improved resistance profiles when compared to raltegravir and elvitegravir (EVG), with few reported cases of resistance in the clinic. This study used in vitro drug selections with primary HIV-1 isolates to examine potential pathways for resistance to EVG and DTG and the investigational drugs BIC and CAB. Thibault Mesplede, Jean-Pierre Routy McGill University, Montreal, QC, Canada

Poster Abstracts

547 157Q INTEGRASE POLYMORPHISM: IN VITRO PHENOTYPIC IMPACT AND IN VIVO VIROLOGIC OUTCOME Charlotte Charpentier 1 , Isabelle Malet 2 , Audrey Rodallec 3 , Laurence Bocket 4 , Corinne Amiel 5 , Laurence Morand-Joubert 6 , Pantxika Bellecave 7 , Thuy T. Nguyen 2 , Anne Maillard 8 , Brigitte Montes 9 , Marie Leoz 10 , Constance Delaugerre 11 , Vincent Calvez 2 , Anne-Geneviève Marcelin 2 , Diane Descamps 1 1 Bichat–Claude Bernard Hospital, Paris, France, 2 Pitié-Salpêtrière Hospital, Paris, France, 3 CHU de Nantes, Nantes, France, 4 CHU de Lille, Lille, France, 5 Tenon Hospital, Paris, France, 6 Saint-Antoine Hospital, Paris, France, 7 CHU de Bordeaux, Bordeaux, France, 8 CHU de Rennes, Rennes, France, 9 CHU de Montpellier, Montpellier, France, 10 Rouen University Hospital, Rouen, France, 11 St. Louis Hospital, Paris, France Background: We assessed prevalence of E157Q integrase (IN) polymorphism across HIV-1 subtypes, in vitro phenotypic susceptibility to the different IN inhibitors (INI) of E157Q site-directed mutants and virological outcome at W48 in patients harboring E157Q virus initiating INI-based regimen. Methods: We analyzed, in a multi-center study, all available IN sequences issued from INI-naïve patients among 17 French ANRS network HIV clinical centers. IN sequencing was performed by Sanger technology using ANRS procedures. E157Q mutation was introduced by site-directed mutagenesis into pNL4.3 and CRF02_AG contexts and assessed in recombinant phenotypic assay using HeLa-P4 cells. Results: 8528 IN sequences from INI-naïve patients were analyzed: 56% subtype B, 23% CRF02_AG and 21% various “Non-B” subtypes. Overall prevalence of E157Q polymorphismwas 2.7% and its distribution among subtypes was 1.7%, 5.6% and 2.2% in B, CRF02_AG and “Non-B” subtypes, respectively. 39 INI-naïve patients with E157Q virus initiated INI-based regimen (19 RAL, 10 EVG and 10 DTG). Among them, 15 patients had VL <50 c/mL at initiation of INI-based regimen and virological suppression was maintained during the follow-up in all but 2 exhibiting viral blip at W48. 24 patients initiated INI-based regimen with a detectable VL (median=4.9 log c/mL): 8 in first-line (5 EVG, 2 RAL, 1 DTG) and 16 ARV-experienced in virological failure with resistant viruses (10 RAL, 3, EVG, 3 DTG). They experienced different virological outcomes depicted in Table 1, not related to the genotypic susceptibility score. INI-discontinuation occurred between W24 and W48 in 3/8 patients in first-line and in 5/16 ARV-experienced patients. Phenotypic analyses showed fold-change of 0.6, 0.9 and 1.9 for RAL, DTG and EVG, respectively

CROI 2018 201