Resistance Analysis of Bictegravir-Emtricitabine-Tenofovir Alafenamide in HIV-1 Treatment-Naive Patients through 48 Weeks

Abstract

In clinical studies GS-US-380-1489 (study 1489) and GS-US-380-1490 (study 1490), bictegravir-emtricitabine-tenofovir alafenamide (B-F-TAF), dolutegravirabacavir-lamivudine (DTG-ABC-3TC), and dolutegravir plus emtricitabine-tenofovir alafenamide (DTGϩF-TAF) treatment achieved high rates of virologic suppression in HIV-1 treatment-naive participants through week 48. Preexisting primary drug resistance was present at levels of 1.3% integrase strand transfer inhibitor resistance (INSTI-R), 2.7% nucleoside reverse transcriptase inhibitor resistance (NRTI-R), 14.1% nonnucleoside reverse transcriptase inhibitor resistance (NNRTI-R), and 3.5% protease inhibitor resistance (PI-R) in the 1,274 participants from these studies. These mutations did not affect treatment outcomes. Resistance analyses in 13 virologic failures found no emergent resistance to study drugs.Of the 1,421 participants with screening genotypes, only 3 had protocol-defined exclusion mutations (1 with M184V, 1 with M184M/V, and 1 with M184V, M41L, L210W, T215F/Y, and K219Q in RT) and were excluded for drug resistance reasons. The studies enrolled and dosed 1,274 participants who showed full sensitivity to FTC and TAF based on the proprietary genotypic algorithm from Monogram Biosciences. No participant had HIV-1 with the tenofovir or FTC-3TC resistance-associated substitutions K65R/E/N or M184V/I, respectively, according to the population genotype at screening. Retrospective deep-sequencing analyses of PR, RT, and integrase (IN) were performed on baseline samples of enrolled participants using the deepType HIV assay (Seq-IT GmbH & Co. KG, Kaiserslautern, Germany), and resistance mutations seen at frequencies of Ն15% were tabulated and combined with population sequencing results (Table 1). The 15% cutoff was chosen to mirror population sequencing thresholds and to ensure that mutations were above the background error of the assay. Primary NRTI resistance (NRTI-R) substitutions were observed in 2.7% (35 of 1,274) of participants, and the most frequent substitutions were M41L and K219E/N/Q/R in RT. These are thymidine analog resistance mutations (TAMs) and remain sensitive to FTC and tenofovir when fewer than three TAMs are present (7). Although not detected by population sequencing at screening, K65R/E was observed by deep sequencing above the 15% threshold in three participants (two with K65E in the B-F-TAF group; frequencies of 15% to 23%). Primary NNRTI resistance (NNRTI-R) substitutions were observed in 14.1% (179 of 1,274) of participants, and the most frequent substitutions were K103N/S and E138A/G/K/Q in RT. Primary protease inhibitor (PI) resistance substitutions were observed in 3.5% (44 of 1,274) of participants, and the most frequent substitutions were M46I/L, Q58E, and L90M in PR. The frequencies of baseline-transmitted resistance to antiretrovirals (ARVs) were consistent with findings of other reports (8-10).No genotyping of HIV integrase (IN) was conducted at screening in studies 1489 and 1490. However, retrospective baseline IN genotypic data...

Integrase Strand Transfer Inhibitors Are Effective Anti-HIV Drugs

“…There are, to date, no reports that resistance to BIC has developed in patients [ 18 ]. IN mutants that reduce the potency of BIC have been identified in vitro in which BIC primarily selected for the M50I, S153F/Y, R263K, and M50I/R263K IN mutants [ 25 , 136 ].…”

“…However, the second-generation INSTIs dolutegravir (DTG) and bictegravir (BIC) are able to effectively inhibit most of HIV-1 IN mutants that arise in response to RAL and EVG ( Figure 1 ) [ 15 , 16 , 17 ]. Although there have been no reports of the development of resistance to DTG and BIC in treatment-naïve individuals who have been put on ART regimens that include these INSTIs [ 18 , 19 , 20 , 21 , 22 ], there has been a poor response to salvage therapies that included DTG in some individuals who had previously failed ART regimens that included a first-generation INSTI [ 16 , 17 ]. In addition, in vitro experiments have identified combinations of mutations in IN that markedly reduce the potencies of both DTG and BIC [ 15 , 23 , 24 , 25 ].…”

Brief Report: Bictegravir/Emtricitabine/Tenofovir Alafenamide Efficacy in Participants With Preexisting Primary Integrase Inhibitor Resistance Through 48 Weeks of Phase 3 Clinical Trials

“…This clinical isolate with Q148H+G140S was phenotypically susceptible to BIC (2.14-fold change, less than the cutoff of 2.5-fold), partially susceptible to DTG (4.45-fold change, greater than the cutoff of 4-fold), and resistant to EVG and RAL (PhenoSense Ò Integrase assay, Monogram Biosciences). 45…”

INSTIs for the management of HIV-associated TB (INSIGHT study): a phase 2b study to evaluate the efficacy, safety and pharmacokinetics of a combination of bictegravir, emtricitabine and tenofovir alafenamide fumarate for the treatment of HIV-1 infection in patients with drug-susceptible tuberculosis on a rifampicin-based treatment regimen: a phase 2b open-label randomised controlled trial

“…2 3 Second generation InSTIs such as dolutegravir and a newer drug, Bictegravir (BIC), have high antiviral potency, better safety and tolerability profiles than protease inhibitors (PIs) and NNRTIs, and are suitable for once daily administration with a high barrier to the development of HIV-1 resistance. [4][5][6][7] BIC may also demonstrate activity against some variants with reduced susceptibility to dolutegravir. In large Phase 3 trials of BIC-emtricitabine -tenofovir alafenamide (BIC/FTC/ TAF 50-200-25, now co-formulated as Biktarvy), there were no cases of emergent resistance.…”