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Co-formulated bictegravir, emtricitabine, and tenofovir alafenamide (BIC/F/TAF) for maintenance of viral suppression in adults with historical virological failure and K65N/R mutation

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BACKGROUND: Real-world experience with co-formulated bictegravir, emtricitabine, and tenofovir alafenamide (BIC/F/TAF) is sparse as a switch regimen among people living with HIV (PLWH) who have achieved viral suppression after prior virologic failures that had resulted in emergence of K65N/R mutation.
METHODS: In this multicenter study, PLWH who were aged 20 years or older and had had a history of virologic failure with emergent K65N/R mutation were included for switch to BIC/F/TAF after having achieved viral suppression (PVL <200 copies/mL) with other antiretroviral therapies for 3 months or longer. Patients were excluded if integrase inhibitor strand transfer inhibitor (InSTI) resistance-associated mutations (RAMs) were detected or had had a history of virologic failure to regimens containing an InSTI. Pre-existent RAMs to nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase Inhibitors (NNRTIs), and protease inhibitors (PIs) were allowed. The primary endpoint was virologic non-response (plasma HIV RNA >50 copies/mL) at Week 48 of switch using a modified FDA snapshot analysis algorithm.
RESULTS: A total of 61 PLWH with a history of virologic failure and K65N/R mutation who were switched to BIC/F/TAF after achieving viral suppression with other combination antiretroviral therapies (Table) were identified between Oct. 2019 and Dec. 2020. The other RAMs of HIV-1 included 36 (59.0%) with M184V/I and 7 (11.5%) with 1 TAM, 55 (90.2%) with NNRTI RAMs, and 3 (4.9%) with PI RAMs. The mean duration of viral suppression prior to switch to BIC/F/TAF was 3.9 years and 57 (93.4%) had PVL <50 copies/mL before switch. After a median observation of 41.3 weeks (range, 4.3-61.0), all of the included patients continued to receive BIC/F/TAF. By week 12, all of 56 included PLWH had PVL <50 copies/mL; 1 of 50 (2.0%) had PVL of 68 copies/mL at week 24 and re-achieved viral re-suppression (<50 copies/ml) at week 36; at week 36, none of 33 had PVL >50 copies/mL; and at week 48, the rate of virologic non-response was 0% (0/17).
CONCLUSIONS: Despite emergence of K65N/R mutation with or without M184V/I in patients having had virologic failures, BIC/F/TAF could be considered as a therapeutic option for treatment simplification after viral suppression was achieved.