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Letter to the editor: switching treatment to lamivudine plus boosted atazanavir or darunavir in virologically suppressed HIV-infected patients – evidence from a large observational cohort

Sir, In a recent issue of Infectious Diseases, Calza et al. [1] presented an interesting retrospective study on HIV combined antiretroviral therapy (cART) simplification with lamivudine (3TC) þ Protease Inibitor/ritonavir (PI/r) regimens. The study was performed on 122 HIV infected subjects, virosuppressed from at least 6 months, and evaluated durability and efficacy over 12 months of follow-up, resulting in a very low rate of discontinuation due to virologic failure or other causes. These results are in line with previous analyses that have already validated the efficacy and durability of dual therapy regimens in HIV viro-suppressed patients [2–4]; in fact, current European HIV treatment guidelines suggest dual therapy with 3TCþ PI/r or Dolutegravir (DTG) þ Rilpivirine as the only recommended alternative switch regimens in patients without resistance to PIs or to DTG, suppression of HIV-Viral Load (VL) to <50 copies/mL for at least the past 6 months and absence of chronic hepatitis B virus co-infection [5]. However, in consideration of the life-long duration of cART and the higher risk of complications typically associated with aging of HIV infected subject, such as osteoporosis, cardiovascular diseases, and other end-organ diseases [6], more studies from “real life” situation and with longer follow up are needed to confirm the value of dual therapy. Hence, we studied a larger cohort from a real-life setting (ARCA database) for evaluating durability and efficacy of the switch strategy to 3TCþ atazanavir/ritonavir (3TCþATV/r) or 3TCþdarunavir/ritonavir (3TCþDRV/r) in cART-experienced HIV-1 infected patients with VL <50 copies/mL. ARCA (antiviral response cohort analysis) is a public observational database created for surveillance of HIV drug resistance and for the implementation of models predictive of virological response to antiviral treatment. Currently ARCA collects data about more than 40,000 HIV1 infected patients followed at >50 clinical centres in Italy. ARCA contains demographic, clinical and treatment data, virological, immunological and drug resistance information, providing a framework for comparative evaluation of recommended as well as less common treatment regimens. We enrolled 314 subjects from ARCA, virologically suppressed from at least 6 months (plasma HIV-1 RNA <50 copies/mL) or experienced isolated viral blips (defined as HIV-RNA between 50 and 200 copies/mL preceded and followed by a value <50 copies/mL), switching to 3TCþATV/r or 3TCþDRV/r retrospectively selected on the basis of the following criteria: (i) age 18 years; (ii) plasma HIV-1 RNA <50 copies/mL at the time of starting; (iii) at least one available viremia measurement after switching; (iv) available CD4 cell count nadir before therapy switching; (v) complete information about treatment history. Patients follow-up was censored at the last available viremia measurement before regimen discontinuation. HIV genotypes were performed at each participating centre on the basis of local procedures and checked for consistency upon sequence uploading into the ARCA database, which stores the sequences, automatically extracts the mutations with respect to HIV-1 consensus B using a built-in local alignment script based on ClustalW and returns a five-level susceptibility score