Background: Intermittent HIV-1 RNA detection in seminal plasma may occur in patients with undetectable plasma viral load (pVL) on standard triple-drug therapy. Few data are available regarding HIV-1 RNA detection in seminal plasma samples from virologically-suppressed patients receiving a maintenance dual therapy, and DTG+3TC in particular.
Patients & Methods: In this ANRS167 LAMIDOL sub-study, a non-comparative open-label, single arm, multicenter trial, semen samples were collected at D0 and W24 of DTG+3TC. HIV-1 RNA was quantified in seminal plasma using COBAS® TaqMan® HIV-1 Test, v2.0 (limit of quantification [LOQ]=100 c/mL). Ultra-sensitive pVL (USpVL) was performed with centrifugation of the maximum volume of available plasma to reach a LOQ of 3 c/mL. The limit of detection (LOD) was defined as an undetected PCR signal. Plasma and seminal plasma drug concentrations (Cmin) were measured using UPLC-MS/MS.
Results: Among the 104 enrolled patients, seminal plasma samples were collected from 18 participants, including 16 paired samples at D0 and W24 of DTG+3TC. Median (IQR 25-75%) total DTG blood plasma Cmin and DTG seminal plasma Cmin were 1880 ng/mL (1377-2337; n=29) and 198 ng/mL (94-239; n=34), respectively. While the unbound/total DTG blood plasma Cmin ratio was 0.21% (0.17-0.25%; n=29), the seminal plasma/blood plasma total DTG Cmin ratio was 12% (8-15%; n=29), suggesting a DTG accumulation in the male genital tract. HIV-1 RNA was detected in seminal plasma of 3 patients: 1 at D0 (5.9%, 95%CI: 0.1-28.6) and 2 other at W24 (11.8%, 95%CI: 1.5-36.4). Seminal viral load was 475, 440 and 365 copies/mL and concomitant USpVL was below the LOD in all three cases. All three participants, except one, presented a DTG Cmin in seminal plasma above the in vitro protein-binding adjusted IC90 values (i.e. 64 ng/mL). These three patients did not experienced virological failure or plasma viral blip along the study and had no concomitant sexually transmitted infection.
Conclusions: No differences were observed regarding seminal plasma HIV-1 RNA detection in patients under triple therapy and at W24 of a maintenance DTG+3TC dual-drug therapy.

Background
HIV drug resistance has a deleterious effect on the virological outcome of antiretroviral therapy (ART). The aim of the study was to evaluate the ability of genotypic susceptibility score (GSS) to predict virological outcome following an ART switch to a 2-drug regimen in virosuppressed HIV-1 infected patients.

Material and methods
From the ARCA database we selected HIV-1 infected patients virologically suppressed switching to 2-drug ART (2006-2018, time of switch=baseline), with pre-baseline resistance genotype and at least one HIV-1 RNA determination during follow up. Primary endopoint was virological failure (VF: an HIV-RNA, VL, >200 cps/mL or 2 consecutive >50 cps/mL). Survival analysis was used to investigate predictors of VF. The GSS predicted by the latest and the cumulative genotype (CGSS) was calculated using the Stanford hivdb (v.8.5) with respect to the 2-drug regimen started. CD4 changes from baseline at weeks 24, 48 and 96 were assessed using Student’s t-test for paired samples.

Results
We included 773 patients: 522 (68%) were males, 186 (24%) heterosexuals, with median age of 50 years (IQR, 43-56), 10 years of HIV (5-20), 7 years of ART and 5 (3-8) previous antiretroviral (ARV) lines. At baseline patients had been virologically suppressed for 6.4 years (2.5-14), allowing isolated blips. The median zenith VL was 4.9 log10 (4.4-5.5), CD4 cells count at nadir 222 (108-324) and at baseline 640 (477-860). Median GSS was 2 (1.5-2), with GSS <2 in 213 (28%) pts, median CGSS was 2 (1-2), with CGSS <2 in 250 (33%). The previous ARV classes used were NRTI in 770 patients (99%), NNRTI in 416 (54%), boosted PI in 639 (83%) and INSTI in 218 (28%). Current ARV regimens included: PI+3TC in 455 pts (59%), of which 3TC+ ATV unboosted or ATV/r or ATV/c in 181 (23%) and DRV/r or DRV/c in 274 (36%), DTG+3TC in 260 (34%) and DTG+RPV in 58 (7%). During a median observation time of 75 wks (37-120) the estimated probability of VF at 48 weeks was 6% (95% CI 5-7) among patients with GSS=2, 4% (3-5) among patients with GSS 1-1.99 and 11% (4-18) among those with GSS <1 (Log Rank p=0.21). According to CGSS, the estimated probability of VF at 48 weeks was 5% (95% CI 1-6) among patients with CGSS =2, 6% (4-8) among patients with CGSS 1-1.99 and 8% (3-13) among those with CGSS <1 (log Rank p=0.006,). Observed median changes of CD4+ counts from baseline were +24 cells/µL (IQR -67;+132) at 24 weeks, +49 cells/µL (IQR -31;+159) at 48 weeks and +74 cells/µL (IQR -30;+197) at 96 weeks (p<0.001 for all comparisons). At multivariate analysis, adjusting for years of ART, CD4 cell count at nadir and at baseline, CGSS strata, number of previous ARV lines, only longer time since last VL>50 cps/mL was associated with lower risk of VF (+ 1 year, aHR 0.89, 95% CI 0.82-0.98; p=0.01).
Conclusions
Despite an effect of CGSS, the duration of virosuppression was the only independent predictor of virological efficacy of switching to 2-drug regimens.

Background
Cabotegravir is the newest integrase strand transfer inhibitor (INSTI) that is being developed as a long-acting injectable for monthly or quarterly administration and as an oral tablet for daily use for the treatment and prevention of HIV-1 infection. During CROI 2019, the FLAIR study was presented which showed that a long-acting regimen of cabotegravir and rilpivirine is non-inferior for HIV maintenance therapy as compared to a dolutegravir, abacavir and lamivudine. Three patients had confirmed virological failure to cabotegravir. These three patients were all from Russia, had a HIV infection with subtype A and a L74I mutation in their baseline integrase sequence. In-vitro studies found that substitutions in the 74 position of the integrase gene, especially together with major (G140A/C/S, Q148 H/K/R) and other accessory mutations (V75I, T97A), can significantly reduce susceptibility to cabotegravir. Although the Stanford HIV drug resistance database states that L74I occurs as a polymorphism in a minority of 21% of subtype A sequences, the database includes sequences from across the World. The aim of this study was to assess the prevalence of L74I in INSTI-naïve sequences from Russia.
Methods
We analyzed integrase (IN), protease (PR) and reverse transcriptase (RT) sequences from 412 HIV-infected INSTI- naïve patients, collected between 2008 and 2018 in Russia: 227 treatment-naïve patients and 185 patients with virological failure to antiretroviral drug therapy. IN and PR-RT sequences were obtained by AmpliSens® HIV-Resist-Seq kit. Viral subtype (PR-RT sequences) and the presence of resistance mutations (IN sequences) were determined using the HIVdb Program v.8.8. (https://hivdb.stanford.edu/).
Results
The most frequent clade in the Russian IN sequences was subtype A (85.9%), followed by subtype B (7.3%), subtype G for 3 (0.7%) and the circulating recombinant forms (CRF) CRF02_AG (4.1%), CRF63_02A1 (1.7%). In our study 196 sequences from 227 treatment-naïve patients contained the accessory mutation L74I. Among subtype A, L74I was detected in 97.9% samples, B - 6.25%, CRF02_AG - 44.4% and CRF63_02A1- 20%. Furthermore, we detected 5 sequences with additional major and/or accessory mutations (sample 1 (Q146P), sample 2 (Y143C/S147A/Q148H + G140L/P145G/S153F), sample 3 (Q146P + G163R), sample 4 (N155A+ S153Y/G163R) and sample 5 (G163R). Similarly, among patients with virological failure of therapy without INSTI, L74I was determined in 157/185 sequences (84.9%). The prevalence of L74I in subtype A, B and CRF02_AG viruses was 95.7%, 7.1% and 25% respectively. In addition to L74I additional relevant substitutions were found in 3 samples, including major drug resistance associated mutations (R263K, S147T) and an accessory mutation (T97A).
Conclusions
Our results demonstrate that in Russia, L74I is present in almost all subtype A sequences, and in a large proportion of CRF02_AG sequences. This high prevalence of L74I should be considered when introducing cabotegravir in Russia.

Background
FTR is a prodrug metabolized to temsavir (TMR), a first-in-class, investigational attachment inhibitor that binds directly to HIV-1 gp160, preventing initial interaction with, and attachment to, CD4 receptors on T-cells and other host immune cells. Previous studies have identified amino acid substitutions at four gp160 positions (S375H/I/M/N/T, M426L/P, M434I/K and M475I) that may influence susceptibility of the envelope to TMR. We present Week 48 efficacy and the potential impact of treatment emergent substitutions in protocol defined virologic failures (PDVF).

Study Design
BRIGHTE is an ongoing Phase 3, randomized, placebo-controlled, double-blind trial evaluating fostemsavir in heavily treatment-experienced patients with multidrug resistant HIV-1. Two cohorts were studied: randomized cohort (RC) with 1 or 2 remaining ARV classes, and non-randomized cohort (NRC) with zero fully active and approved ARVs. Week 48 efficacy was assessed using the FDA snapshot analysis. Full genotypic and phenotypic analysis was performed on all participants at Screening, to evaluate eligibility and to assess options for OBT, and at failure. TMR susceptibility was assessed using the Monogram PhenoSense Entry assay and gp160 substitutions were assessed at these timepoints. There was no TMR IC50 entry criteria. Changes in TMR IC50 FC (fold change) <3x were considered within the variability of the testing assay.
Results
At Week 48, 54% of RC and 38% of NRC achieved virologic suppression (HIV-1 RNA <40 c/mL). The proportion of participants with prior exposure and pre-existing genotypic substitutions to approved ARV agents was extensive (NRC >RC). Genotypic polymorphisms in gp160 at 1 or more positions of interest were present at baseline in 45% of treated participants. Median baseline TMR IC50 FC was 0.99-fold; 87% of participants had IC50 FC ≤100 (range from 0.04 to >9,000-fold from reference). Day 8 median decreases in HIV RNA were 1.032 log vs. 0.652 log for participants without and with baseline polymorphisms at positions of interest, respectively. Presence of these polymorphisms at Screening did not affect virologic response (VL< 40 c/mL) at Week 48 in the RC. Rates of PDVF at Week 48 were 18% (49/272-RC) and 46% (46/99-NRC), including some participants who re-suppressed beyond Week 48. Overall, in evaluable PDVFs, 52/93 (56%) had treatment emergent genotypic substitutions at positions of interest. Median increase in TMR FC in the RC was 2.34. As expected, more participants in NRC experienced a greater median increase in TMR FC (469.7). The most frequent emergent changes were M426L (33 participants-35%), and S375N (29 participants-31%). The emergence of genotypic and phenotypic resistance to OBT agents was consistent with observations in similar studies.

Conclusions
In BRIGHTE, Week 48 rates of virologic response and PDVF were comparable to other studies performed in similar patient populations. Emergent substitutions mapped to the 4 prespecified amino acid positions, while their presence at baseline in the RC did not impact Week 48 response. The clinical evaluation of PDVF and TMR susceptibility remains context dependent; therefore, more data will be required to reach a clinical cut-off for FTR. The Week 48 data continue to show the benefit of FTR in the HTE population.

Background: Doravirine (DOR), a novel HIV-1 non-nucleoside reverse transcriptase (NNRTI), in combination therapy, has non-inferior efficacy to darunavir/r (800/100 mg) or efavirenz (600 mg) in treatment-naïve patients. DOR has an in vitro resistance profile that is distinct from other NNRTIs retaining activity against viruses containing the most frequently transmitted NNRTI mutations, K103N, Y181C and G190A. DOR selects for distinct mutations in vitro, including mutations at reverse transcriptase (RT) positions 106, 108, 188, 227, 230 and 234. The aim of this study was to examine the prevalence of DOR-associated resistance mutations in HIV-1-infected antiretroviral-experienced patients.

Materials & Methods: Resistance genotypic tests were performed at five reference laboratories, 2 in Paris (Pitié-Salpêtrière and Bichat Claude Bernard hospitals) and 3 in Italy (University/polyclinic of Rome Tor Vergata, INMI Spallanzani-IRCCS, Modena Hospital). A total of 9199 HIV-1 RT sequences obtained between 2012 and 2017 from HIV-1 antiretroviral-experienced patients in routine clinical care were analysed. Among this set of sequences, 381 sequences were originated from NNRTI-failing patients. DOR-associated mutations identified in vitro or in vivo were considered: RT V106A/M, V108I, Y188L, G190S, F227C/L/V, M230I/L, L234I, P236L, K103N+Y181C, K103N+P225H, K103N+L100I. The sequences were also interpreted according to the ANRS algorithm to predict genotypic resistance to DOR.

Results: Among the 9199 sequences, 4056 and 5143 were performed between 2012-2014 and 2015-2017, respectively. The distribution of subtypes was: 45.3% B, 27.3% CRF02_AG, 3.7 % A1, 2.5% C, 1.7% CRF06_cpx and 19.5% other various non-B. Among the DOR-associated mutations, the frequencies of mutations (total set vs NNRTI-failing patients) were V106A/M (0.8% vs 2.6%), V108I (3.3% vs 9.2%), Y188L (1.2% vs 2.6%), G190S (0.3% vs 2.1%), M230I/L (2.8% vs 0%), K103N+Y181C (3.9% vs 3.9%), K103N+P225H (2.9% vs 4.7%) and K103N+100I (1.7% vs 3.9%) with a significant higher proportion of these resistance mutations in the NNRTI-failing group (p<0.05), except for K103N+Y181C. The overall prevalence of sequences with at least 1 DOR-associated mutation was 12.2% and 34.9% in total set and NNRTI-failing patients, respectively. Among NNRTI-failing patients, the prevalence of common NNRTI mutations V90I, K101E/P, K103N/S, E138A/G/K/Q/R/S, Y181C/I/V, G190A/E/S/Q were 8.9%, 7.9%, 28.6%, 12.6%, 14.2%, 8.9%, respectively. Thus, in the NNRTI-failing group, according to the ANRS algorithm, 18.1% (n = 69) of sequences were genotypically resistant to DOR whereas 36.5% (n=139) were genotypically resistant to nevirapine (p<0.0001), 51.7% (n = 197) to efavirenz (p<0.0001), 21.9% (n=88) to etravirine (p=0.1067) and 55.6% (n=212) to rilpivirine (p<0.0001).

Conclusions: These results suggest that DOR resistance in antiretroviral-experienced patients generally and specifically also NNRTI-failures is significantly lower than resistance to NNRTIs currently used, supporting the use of DOR in experienced patients, considering its distinguishing resistance pattern.