Antiretroviral reduction: is it time to rethink the unthinkable?

Two-drug regimens for HIV treatment

Combination therapy with three antiretroviral agents has been integral to successful HIV-1 treatment since 1996. Although the efficacy, adverse effects, and toxicities of contemporary three-drug regimens have improved, even the newest therapies have potential adverse effects. The use of two-drug regimens is one way to reduce lifetime exposure to antiretroviral drugs while maintaining the benefits of viral suppression. Multiple large, randomised trials have shown the virological non-inferiority of certain two-drug regimens versus three-drug comparators, including adverse effect differences that reflect known profiles of the antiretroviral drugs in the respective regimens. Two-drug combinations are now recommended in treatment guidelines and include the first long-acting antiretroviral regimen for the treatment of HIV-1. Recommended two-drug regimens differ in their risks for, and factors associated with, virological failure and emergent resistance. The tolerability, safety, metabolic profiles, and drug interactions of two-drug regimens also vary by the constituent drugs. No current two-drug regimen is recommended for people with chronic hepatitis B virus as none include tenofovir. Two-drug regimens have increased options for individualised care.

Individualized Protease Inhibitor Monotherapy: The Role of Pharmacokinetics and Pharmacogenetics in an Aged and Heavily Treated HIV-Infected Patient

Antiretroviral therapy has changed the history of HIV infection from a lethal disease to a chronic infection, with the emergence of long-term adverse effects. Herein we present a case of a heavily treated HIV-infected man in whom antiretroviral toxicity had been observed. The lopinavir/ritonavir plasma concentrations at standard doses were significantly above the recommended levels. Pharmacogenetic analysis revealed a polymorphism in the DRD3 gene associated with a decrease in the rate of drug metabolism. Additionally, the patient's low body mass index could have contributed to a greater degree of patient exposure to the drug. After the withdrawal of tenofovir disoproxil and the establishment of individualized protease inhibitor monotherapy at reduced doses, a decrease in the intensity of adverse events was observed, while the clinical outcomes were maintained. The pharmacokinetic-pharmacogenetic analysis was shown to be a tool of huge interest for the management and durability of antiretroviral therapy.

Dolutegravir-based monotherapy or dual therapy maintains a high proportion of viral suppression even in highly experienced HIV-1-infected patients

Background

Dolutegravir is a powerful, well-tolerated integrase inhibitor with a high genetic barrier to resistance and may thus constitute the backbone of lightened regimens.

Methods

This was a monocentric, retrospective study. HIV-1-infected patients receiving dolutegravir as monotherapy (mDGV) or dual therapy (dDGV) were systematically identified. The primary outcome was the proportion of patients who maintained undetectable (<50 copies/mL) plasma HIV RNA [plasma viral load (PVL)].

Results

We identified 21 patients on mDGV (50 mg/day) and 31 on dDGV (50 or 100 mg/day, with atazanavir ± ritonavir, n = 12; rilpivirine, n = 11; maraviroc, n = 3; lamivudine, n = 3; darunavir/ritonavir, n = 1; or abacavir, n = 1). All of the patients were treatment experienced and 48% had experienced at least one virological failure. The baseline characteristics were as follows (for the mDGV/dDGV patients, respectively): 5%/29% had a history of AIDS; the median (IQR) highest PVL was 4.5 (4.3–5.5)/5.3 (4.7–5.6) log copies/mL; the median (IQR) nadir CD4+ count was 310 (280–468)/199 (134–281) cells/mm³; 100% had undetectable PVL before the mDGV for a median (IQR) duration of 5.9 (3.5–9.9) years/81% had undetectable PVL before the dDGV for a median (IQR) duration of 3.7 (1.4–8.3) years; and the median (IQR) HIV DNA level was 2.7 (2.1–3.1)/2.9 (2.7–3) log copies/10⁶ PBMCs. At the last follow-up visit, 100% and 97% of patients showed undetectable PVL following mDGV and dDGV, respectively [median (IQR) follow-up of 32 (29–45) and 50 (30–74) weeks, respectively].

Conclusions

In our experience, dolutegravir-based lightened regimens provided a high proportion of viral suppression, even in highly treatment-experienced patients.

Darunavir-based dual therapy of treatment-experienced HIV-infected patients: analysis from a national multicenter database

BACKGROUND

We assessed the virological response of dual therapy with DRV/r, plus raltegravir, maraviroc or etravirine, in virological failure patients and in virologically suppressed patients collected in the Italian Antiretroviral Resistance Database (ARCA).

MATERIAL AND METHODS

The primary endpoint was the percentage of patients remaining free of virological failure (confirmed >50 copies/mL or any change in the regimen). Subjects had a resistance test and at least one follow-up visit. Observation was censored at last visit under dual therapy and survival analysis and proportional hazard models were used.

RESULTS

Sixty-seven percent of the 221 patients started DRV/r with RAL, 20.4 % with ETV, and 12.2 % with MAR; 31.2 % virological failures were observed. At survival analysis, the overall proportion of failure was 29.2 % at 1 year and 33.8 % at 2 years. The proportion of failure was lower in patients starting with undetectable vs. detectable viral load (13.3 and 25.2 % vs. 37.4 and 38.8 % at 1 and 2 years, respectively, p = 0.001 for both analyses) and in patients treated with DRV 600 BID vs. 800 QD (HR: 0.56, 95 % CI: 0.31-0.99, p < 0.05). By regimen, the adjusted proportional model showed no significant difference among the three regimens. A significant lower risk of failure was associated with higher GSS (HIV-DB HR: 0.53, 95 % CI: 0.32-0.88, p = 0.014; Rega 0.60, 0.40-0.88, p < 0.01; ANRS 0.55, 0.34-0.90, p = 0.017), while a higher risk of failure with detectable HIV-RNA (3.02, 1.70-5.72, p < 0.001).

CONCLUSIONS

Among experienced patients, the best candidates for dual-therapy regimens including DRV/r are those with undetectable viral load and higher GSS.

Simplification to atazanavir/ritonavir monotherapy for HIV-1 treated individuals on virological suppression: 48-week efficacy and safety results

OBJECTIVES

The objective of this study was to assess the 48-week virological efficacy of atazanavir/ritonavir (ATV/r) monotherapy vs. ATV/r along with two nucleoside reverse transcriptase (NRTIs) in HIV-1 treated individuals with HIV-RNA less than 50 copies/ml.

METHODS

A multicentre, randomized, open-label, noninferiority trial. HIV-1 treated individuals on ATV/r 300/100 mg along with two NRTIs were randomized to receive ATV/r monotherapy or to maintain their antiretroviral regimen. The primary endpoint was the confirmed viral rebound (CVR: two consecutive HIV-RNA >50 copies/ml) or treatment discontinuation for any reason. Individuals who experienced CVR on ATV/r monotherapy reintroduced NRTIs and discontinued the study if HIV-RNA was more than 50 copies/ml after 12 weeks since reintensification.

RESULTS

One hundred and three patients enrolled. By week 48, 11 patients in ATV/r arm and two in ATV/r along with two NRTIs experienced CVR; four (8%) patients in ATV/r and eight (15%) in ATV/r along with two NRTIs discontinued. At the 48-week primary efficacy analysis (re-intensification = failure), treatment success was 73% in ATV/r arm and 85% in ATV/r along with two NRTIs [difference -12.1%, 95% confidence interval (95% CI) -27.8 to 2.1]. According to the analysis considering re-intensification is equal to success, treatment success was 92% in ATV/r arm and 85% in the ATV/r along with two NRTIs arm (difference 7.5%, 95% CI -4.7 to 19.8). At CVR, no mutation was observed in ATV/r arm and reintensification with NRTIs was effective in all individuals. Overall, Grade 3-4 (P = 0.003) and grade 3-4 drug-related (P = 0.027) adverse events were less frequent in ATV/r arm. A significant increase in total and low-density lipoprotein (LDL)-cholesterol was observed as well as a significant improvement in high-density lipoprotein (HDL)-cholesterol, fasting glucose, liver fibrosis and alkaline phosphatase was observed in ATV/r monotherapy in comparison with ATV/r along with two NRTIs.

CONCLUSION

ATV/r monotherapy treatment simplification showed lower virological efficacy in comparison with maintaining triple therapy; NRTIs reintroduction was effective in all the individuals.