Kinetics of Archived M184V Mutation in Treatment-Experienced Virally Suppressed HIV-Infected Patients

Background We aimed to assess the kinetics of drug-resistant viral variants (DRVs) harboring the M184V mutation in proviral DNA of long-term virally suppressed patients, and factors associated with DRV persistence. Methods Human immunodeficiency virus (HIV) DNA from blood cells stored in 2016 and 2019 was sequenced using Sanger and ultradeep sequencing (SS and UDS; detection threshold 1%) in antiretroviral therapy (ART)-treated patients with HIV RNA < 50 copies/mL for at least 5 years, with past M184V mutation documented in HIV RNA. Results Among 79 patients, by combining SS and UDS, M184V was found to be absent in 26/79 (33%) patients and persistent in 53/79 (67%). M184V-positive patients had a longer history of ART, lower CD4 nadir, and higher pretherapeutic HIV RNA. Among 37 patients with viral sequences assessed by UDS, the proportion of M184V-positive DRVs significantly decreased between 2016 and 2019 (40% vs 14%, P = .005). The persistence of M184V was associated with duration and level of HIV RNA replication under lamivudine/emtricitabine (3TC/FTC; P = .0009 and P = .009, respectively). Conclusions While it decreased over time in HIV DNA, M184V mutation was more frequently persistent in HIV DNA of more treatment-experienced patients with longer past replication under 3TC/FTC.

Antiviral Activity of Tenofovir Alafenamide against HIV-1 with Thymidine Analog-Associated Mutations and M184V

ABSTRACT Tenofovir alafenamide (TAF) and tenofovir disoproxil fumarate (TDF) are prodrugs of the HIV-1 nucleotide reverse transcriptase inhibitor tenofovir (TFV). In vivo, TAF achieves >4-fold-higher intracellular levels of TFV diphosphate (TFV-DP) compared to TDF. Since thymidine analog-associated mutations (TAMs) in HIV-1 confer reduced TFV susceptibility, patients with TAM-containing HIV-1 may benefit from higher TFV-DP levels delivered by TAF. Moreover, the presence of the M184V mutation increases TFV susceptibility during TDF- or TAF-based therapy. The susceptibilities to antiviral drugs of site-directed mutants (SDMs) and patient-derived mutants containing combinations of TAMs (M41L, D67N, K70R, L210W, T215Y, and K219Q) with or without the M184V mutation (TAMs±M184V) were evaluated using either 5-day multicycle (MC; n = 110) or 2-day single-cycle (SC; n = 96) HIV assays. The presence of M184V in TAM-containing HIV-1 SDMs (n = 48) significantly increased TAF sensitivity compared to SDMs without M184V (n = 48). The comparison of TAF and TDF resistance profiles was further assessed in viral breakthrough (VB) experiments mimicking clinically relevant drug concentrations. A total of 68 mutants were assayed at physiological concentration in VB experiments, with 15/68 mutants breaking through with TDF (TFV, the in vitro equivalent of TDF, was used in these experiments), and only 3 of 68 mutants breaking through under TAF treatment. Overall, in the VB assay mimicking the 4-fold-higher intracellular levels of TFV-DP observed clinically with TAF versus TDF, TAF inhibited viral breakthrough of most TAM-containing HIV-1, whereas TDF did not. These results indicate that TAF has a higher resistance threshold than TDF and suggest that higher resistance cutoffs should be applied for TAF compared to TDF in genotypic and phenotypic resistance algorithms.

2508. Virologic Suppression in Patients Switched to BIC/TAF/FTC with Baseline NRTI and/or INSTI Resistance

Background BIC/TAF/FTC is the first fixed-dose combination tablet to contain both a second-generation INSTI and TAF and has therefore become a popular treatment option for HIV. Historically, patients with NRTI mutations were placed on four-drug, NRTI-retaining regimens or two-drug, NRTI-sparing regimens. Recently, data have emerged supporting the use of second-generation INSTIs with tenofovir/FTC in the setting of the M184V mutation alone. There is a paucity of data, however, evaluating the use of BIC/TAF/FTC in the setting of NRTI and/or INSTI mutations. This study assessed the role of BIC/TAF/FTC in patients with baseline NRTI and/or INSTI mutations. Methods This was an observational retrospective study conducted at an inner city HIV clinic. Patients were eligible if they were switched to BIC/TAF/FTC with confirmed adherence and had either the M184V mutation alone, M184V plus another NRTI mutation(s), an INSTI mutation alone, or both NRTI and INSTI mutation(s) at the time of ART switch. We evaluated virologic response (HIV RNA < 200 copies/mL) and duration of BIC/TAF/FTC therapy. Results There were 16 patients eligible for analysis. Among the patients, 69% were male and 31% were female. The majority of patients were Black (81%). The mean age was 63 years (SD ± 8.6). Thirteen patients were virologically suppressed (HIV RNA < 200 copies/mL) at baseline. The mean CD4 count at baseline was 630.4 cells/mm3 (SD ± 297.1). Mutations at baseline were as follows: M184V alone (25%), M184V plus another NRTI mutation(s) (56.25%), INSTI mutation alone (12.5%), NRTI and INSTI mutation(s) (6.25%). BIC/TAF/FTC mean duration of therapy was 10.5 months (range 6–14 months). The mean CD4 count of the patients switched to BIC/TAF/FTC was 687 cells/mm3 (SD ± 20.7). All patients switched to BIC/TAF/FTC achieved or maintained virologic suppression (HIV RNA < 200 copies/mL) with a mean HIV RNA of 26.25 copies/mL (SD ± 14.1). Fifteen of those switched to BIC/TAF/FTC had an undetectable HIV RNA level (HIV RNA < 50 copies/mL). Conclusion While a larger cohort and longer follow-up period is needed, BIC/TAF/FTC may maintain virologic suppression in patients with select baseline NRTI and/or INSTI mutations. Disclosures All authors: No reported disclosures.

A10 Presence and frequency of M184V mutation in the MOBIDIP trial

The MOBIDIP trial evaluated the simplification by protease (PI/r) monotherapy for HIV infection versus dual therapy and boosted protease inhibitor plus lamivudine (PI/r + 3TC) in controlled patients under second-line regimens. MOBIDIP was interrupted because of a significant number of patients with virological failure (VF) at week 48 (W48) in PI/r (33/133, ∼25%) versus in PI/r + 3TC (4/132, ∼3%). At the time of first-line VF, 96 per cent of patients harbored the M184V mutation. The presence of the M184V mutation was related to a protective effect against VF in the PI/r + 3TC arm. We developed a methodology that allows to determine the frequency of M184V/I mutations in the HIV reverse transcriptase (RT) gene in peripheral blood mononuclear cells (PBMC) obtained before MOBIDIP simplification. Paired-end sequences were obtained from 252 PBMC samples covering the first 855 bp of the RT gene (HXB2: 2485–3405) by MiSeq technology. These sequences were subjected to an in-house Bioinformatics pipeline. The results of our pipeline were compared to the output of PASeq (https://www.paseq.org), an open web-tool for the identification of drug resistance mutations. The M184V mutation was identified at a frequency greater than 1 per cent in 178 individuals (∼71%). The M184I mutation was observed in 34 patients (∼13%), always in the presence of stop codons, and is in agreement with expectations, as this mutation is a known APOBEC-targeted site. Sixty-seven patients (∼27%) had a frequency of the M184V mutation with values greater than 75 per cent. PASeq confirmed the presence of M184V mutation in 173 patients. The frequencies estimated by the PASeq tool and in-house pipeline were correlated up to 99.5 per cent. We found a significant loss of the M184V mutation archived in PBMC between the first-line regimen treatment failure and the beginning of the MOBIDIP trial. In patients under long-term antiretroviral therapy, as in our case, viral sub-populations could be lost, reducing the presence, and frequency of a mutation. In the next step, we will evaluate the association between the presence and frequency of M184V mutation and MOBIDIP results.

Antiretroviral Therapy Prescribing Practices and Virologic Response in HIV-Infected Individuals with the M184V Mutation: Results from the 550 Clinic Cohort Study

Background Human immunodeficiency virus (HIV) treatment guidelines recommend using a regimen that contains three fully active antiretroviral agents in patients with drug resistance mutations. However, some evidence suggests that protease inhibitor (PI) based regimens containing less than three fully active drugs may be as efficacious in achieving viral suppression (VS) as a three-drug regimen in the presence of a M184V mutation. The purpose of this study was to identify current prescribing practices and determine if VS can be achieved with regimens containing less than three fully active agents in patients with a M184V mutation. Methods A single-center retrospective chart review was conducted on patients receiving treatment at the 550 Clinic from January 2003 to July 2016. Patients were screened for a M184V mutation. Patients were excluded for lack of a genotype and inadequate documentation of viral load (VL) prior to initiating or changing therapy. Regimens were characterized as containing three fully active agents or less and evaluated for VS success (VL less than 200 copies/mL). Data was analyzed using descriptive statistics, Chi-square tests, and Fischer’s exact tests. Results A M184V mutation was identified in 100 of the 754 patients screened for inclusion. 90% of the 167 regimens evaluated contained less than three fully active drugs. PI-based regimens (n = 86) and integrase strand transfer inhibitor (INSTI)-based regimens (n = 25) were the most commonly prescribed regimens containing less than three fully active drugs. VS was achieved with 72% of regimens containing less than three fully active agents compared with 69% of those containing three fully active agents (P = 0.108). In patients with a baseline VL greater than 100,000 copies/mL, VS was achieved with 80% of INSTI-based regimens compared with 21% of PI-based regimens (P = 0.040). VS was achieved with 85% of INSTI-based regimens and 78% of PI-based regimens in those with a baseline VL less than 100,000 copies/mL (P = 0.513). Conclusion Regimens containing less than three fully active drugs may be as efficacious as regimens containing three fully active drugs in those with a M184V mutation. In those with a high baseline VL, INSTI-based regimens may have better efficacy compared with PI-based regimens. Disclosures All authors: No reported disclosures.

Detection of Latent HIV-1 Infection and Drug Resistant Mutation Testing in Nepal: HIV-1 env V3 DNA Sequence and RT Gene (M184V) Mutation

HIV-1 resistance to antiretroviral therapy (ART) is a crucial issue, despite various effective drugs are available for the treatment. Although the viral RNA is suppressed below the detection limit (<50 copies/ml) with the use of potent antiviral drugs, the mutation can be archived in the cellular reservoir as proviral DNA. The detection of proviral DNA and mutation screening in HIV 1 RNA for genotypic resistance is the sole basis for monitoring the effectiveness of ART. Our study aim to access the extent of latent HIV infections by detecting env V3 DNA and also testing of M184V (meth184val; ATG - GTG substitution at 184th codon) specific mutations in HIV-1 RT gene to monitor the effectiveness of ART. The HIV-1 env V3 DNA sequence was amplified using multiple upstream and downstream primes to show the latent HIV infections, whereas polymerase chain reaction- restriction fragment digestion assay (PCR-RFDA) was used for testing M184V mutation in HIV-1 RT gene. In the study, out of 15 HIV infected patient blood samples, 12 shows amplification of env V3 DNA, confirming the latent HIV infections while 3 were negative for env V3 DNA. HIV-1 RT gene tested for M184V mutation in all 15 samples showed wild type after analysis using PCR-RFDA. After digestion with CviAII, three bands were observed in wild type whereas in mutant only two bands. Although the study shows negative for the M184V resistance mutation, screening of various panels of drug resistance mutations should be performed in recently infected HIV-1 patients for planning the effective ART strategy. The data is not enough to compare the overall scenario of the Nepal thus warrant urgency for large scale study with standard genotypic tools.