Successful pharmacogenetics-based optimization of unboosted atazanavir plasma exposure in HIV-positive patients: a randomized, controlled, pilot study (the REYAGEN study).

BACKGROUND: Atazanavir without ritonavir, despite efficacy and tolerability, shows low plasma concentrations that warrant optimization. METHODS: In a randomized, controlled, pilot trial, stable HIV-positive patients on atazanavir/ritonavir (with tenofovir/emtricitabine) were switched to atazanavir. In the standard-dose arm, atazanavir was administered as 400 mg once daily, while according to patients' genetics (PXR, ABCB1 and SLCO1B1), in the pharmacogenetic arm: patients with unfavourable genotypes received 200 mg of atazanavir twice daily. EudraCT number: 2009-014216-35. RESULTS: Eighty patients were enrolled with balanced baseline characteristics. The average atazanavir exposure was 253 ng/mL (150-542) in the pharmacogenetic arm versus 111 ng/mL (64-190) in the standard-dose arm (P < 0.001); 28 patients in the pharmacogenetic arm (75.7%) had atazanavir exposure >150 ng/mL versus 14 patients (38.9%) in the standard-dose arm (P = 0.001). Immunovirological and laboratory parameters had a favourable outcome throughout the study with non-significant differences between study arms. CONCLUSIONS: Atazanavir plasma exposure is higher when the schedule is chosen according to the patient's genetic profile.

Etravirine plasma exposure is associated with virological efficacy in treatment-experienced HIV-positive patients.

Etravirine is a non-nucleoside reverse transcriptase inhibitor used in combination with other antiretrovirals for the treatment of HIV infection. Given previous conflicting results aim of this study was to investigate whether etravirine plasma exposure was associated with virological outcome. Adult HIV-positive patients starting etravirine with detectable HIV viral loads were included if highly adherent (<90% of the doses) and if steady-state plasma concentrations were available (measured through a validated HPLC-PDA method). Virological success was defined as reaching and maintaining viral suppression (HIV RNA <50copies/mL) during follow up. Fifty-nine (84.7% male) patients were included: baseline CD4+ T-lymphocyte and HIV RNA were 276cells/µL (101-419) and 3.99Log10copies/mL (3.11-4.91), respectively. Darunavir/ritonavir (n=21, 35.6%) and raltegravir plus maraviroc (n=33, 55.9%) were the most common associated antiretrovirals. 240 trough samples were available (3-7 per patient); etravirine trough concentrations (Ctrough) and weighted genotypic inhibitory quotients (wgIQ) were 426ng/mL (266-763) and 408ng/mL/mutation (227-663), respectively. Virological success was observed in 49 patients (83.1%). Genotypic sensitivity of associated drugs (GSS) ⩾2 (p=0.03), etravirine Ctrough >300ng/mL (p=0.02) and etravirine wgIQ >276ng/mL/mutation (p=0.02) were associated with virological success; at multivariate Cox proportional analysis etravirine wgIQ <276ng/mL/mutation (p=0.012) and baseline CD4 <200cell/µL (p=0.043) were independently associated with virological failure. In a cohort of experienced patients etravirine exposure as well as immune status were associated with virological success; two cut off values (300ng/mL and 276ng/mL) were proposed for etravirine Ctrough and wgIQ and need to be confirmed in prospective studies.