Cobicistat: a new opportunity in the treatment of HIV disease?

Uptake and Discontinuation of Integrase Inhibitors (INSTIs) in a Large Cohort Setting

BACKGROUND

Despite increased integrase strand transfer inhibitor (INSTI) use, limited large-scale, real-life data exists on INSTI uptake and discontinuation.

SETTING

International multicohort collaboration.

METHODS

RESPOND participants starting dolutegravir (DTG), elvitegravir (EVG), or raltegravir (RAL) after January 1, 2012 were included. Predictors of INSTI used were assessed using multinomial logistic regression. Kaplan-Meier and Cox proportional hazards models describe time to and factors associated with discontinuation.

RESULTS

Overall, 9702 persons were included; 5051 (52.1%) starting DTG, 1933 (19.9%) EVG, and 2718 (28.0%) RAL. The likelihood of starting RAL or EVG vs DTG decreased over time and was higher in Eastern and Southern Europe compared with Western Europe. At 6 months after initiation, 8.9% (95% confidence interval: 8.3% to 9.5%) had discontinued the INSTI (6.4% DTG, 7.4% EVG, and 14.0% RAL). The main reason for discontinuation was toxicity (44.2% DTG, 42.5% EVG, 17.3% RAL). Nervous system toxicity accounted for a higher proportion of toxicity discontinuations on DTG (31.8% DTG, 23.4% EVG, 6.6% RAL). Overall, treatment simplification was highest on RAL (2.7% DTG, 1.6% EVG, and 19.8% RAL). Factors associated with a higher discontinuation risk included increasing year of INSTI initiation, female gender, hepatitis C coinfection, and previous non-AIDS-defining malignancies. Individuals in Southern and Eastern Europe were less likely to discontinue. Similar results were seen for discontinuations after 6 months.

CONCLUSIONS

Uptake of DTG vs EVG or RAL increased over time. Discontinuation within 6 months was mainly due to toxicity; nervous system toxicity was highest on DTG. Discontinuation was highest on RAL, mainly because of treatment simplification.

Pharmacokinetic drug evaluation of ritonavir (versus cobicistat) as adjunctive therapy in the treatment of HIV

Introduction: Ritonavir and cobicistat are pharmacoenhancers used to improve the disposition of other HIV antiretrovirals. These drugs are, however, characterized by important pharmacokinetic differences.Areas covered: Here, the authors firstly update the available information on the pharmacokinetics of ritonavir and cobicistat. Subsequently, the review focuses on the description of drug-drug interactions (DDIs) involving cobicistat and comedications that might beneficiate from a shift-back to ritonavir. A MEDLINE Pubmed search for articles published from January 1995 to April 2019 was completed matching the term ritonavir or cobicistat with pharmacokinetics, DDIs, and pharmacology. Moreover, additional studies were identified from the reference list of retrieved articles.Expert opinion: Despite more than 20 years after its introduction on the market, ritonavir still represents a valid option for the treatment of selected HIV-infected patients. The large-scale switch to cobicistat may result in some unexpected DDIs not previously reported for ritonavir. Besides the issue of DDIs, additional advantage of ritonavir over cobicistat is its use in pregnancy, and its availability as single component of pharmaceutical formulations allowing the fine-tuning of antiretroviral regimens in patients with heavy polypharmacy when other unboosted-based therapeutic options cannot be used.

Durability, safety, and efficacy of rilpivirine in clinical practice: results from the SCOLTA Project

Rilpivirine is associated with a good efficacy and safety profile. However, data from real-life settings are scarce.

Precision medicine for HIV: where are we?

To date, antiretroviral therapy is highly effective in HIV-affected patients, but the individualization of such a life-long therapy may be advised. This review briefly summarizes the main factors involved in the potential personalization of antiretroviral treatment. Relevant articles in English were identified by PubMed and recent congresses’ abstracts. Foremost influences concerning pharmacodynamics, therapeutic drug monitoring, pharmacogenetics, comorbidities, immune recovery and viral characteristics affecting the healthcare of HIV-positive patients are listed here. Furthermore, pharmacoeconomic aspects are mentioned. Applying pharmacokinetic and pharmacogenetic knowledge may be informative and guide the better choice of treatment in order to achieve long-term efficacy and avoid adverse events. Randomized investigations of the clinical relevance of tailored antiretroviral regimens are needed in order to obtain a better management of HIV/AIDS-affected patients.

Inhibition of human cytochromes P450 in vitro by ritonavir and cobicistat

OBJECTIVES

Ritonavir and cobicistat are strong inhibitors of human cytochrome P450-3A (CYP3A) isoforms, and are used clinically as pharmacokinetic boosting agents for other antiretroviral drugs. Data reported by the manufacturer suggest that cobicistat is a more selective inhibitor of CYP3A than ritonavir. However, this claim has not been validated in clinical studies. This study evaluated the in-vitro inhibitory potency of ritonavir and cobicistat vs a series of human CYP isoforms.

METHOD

The model system utilized human liver microsomes and isoform-selective index substrates.

KEY FINDINGS

Ritonavir and cobicistat both were strong inhibitors of CYP3A4, with IC₅₀ values of 0.014 and 0.032 μm, respectively. A component of inhibition was time-dependent (mechanism-based). Neither drug meaningfully inhibited CYP1A2 (IC₅₀  > 150 μm). CYP2B6, CYP2C9, CYP2C19 and CYP2D6 were inhibited by both drugs, but with IC₅₀ values exceeding 6 μm.

CONCLUSIONS

Consistent with previous reports, both ritonavir and cobicistat were highly potent inhibitors of CYP3A. Both drugs were weaker inhibitors of other human CYPs, with IC₅₀ values at least two orders of magnitude higher. There was no evidence of a meaningful difference in selectivity between the two drugs.

Switch to Rilpivirine/Emtricitabine/Tenofovir Single-Tablet Regimen of Human Immunodeficiency Virus-1 RNA-Suppressed Patients, Agence Nationale de Recherches sur le SIDA et les Hépatites Virales CO3 Aquitaine Cohort, 2012-2014

We evaluated the efficacy and tolerability of a single-tablet regimen strategy in 304 HIV-1 virologically suppressed patients switching to RPV/FTC/TDF for adverse events or treatment simplification. This strategy maintained virologic suppression and was associated with improved tolerability after 12 months follow-up.

Background. The purpose of this study was to assess the efficacy and tolerability of combined antiretroviral therapy (cART) in human immunodeficiency virus (HIV)-1 virologically suppressed patients who switched to rilpivirine (RPV)/tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) as a single-tablet regimen (STR).

Methods. A retrospective multicenter cohort study was performed between September 2012 and February 2014 in Bordeaux University Hospital-affiliated clinics. Patients with a plasma HIV viral load (VL) lower than 50 copies/mL and switching to STR were evaluated at baseline, 3, 6, 9, and 12 months from switch time (M3, M6, M9, M12) for VL and other biological parameters. Change from baseline in CD4 cell counts was evaluated at M6 and M12. Virological failure (VF) was defined as 2 consecutive VL >50 copies/mL.

Results. Three hundred four patients were included in the analysis. Single-tablet regimen switch was proposed to 116 patients with adverse events, mostly efavirenz (EFV)-based (n = 59), and to 224 patients for cART simplification. Thirty of 196 patients with available genotype resistance test results displayed virus with ≥1 drug resistance mutation on reverse-transcriptase gene. After 12 months of follow-up, 93.4% (95.5% confidence interval, 89.9–96.2) of patients remained virologically suppressed. There was no significant change in CD4 cell count. During the study period, 5 patients experienced VF, one of them harboring RPV resistance mutation. Clinical cART tolerability improved in 79 patients overall (29.9%) at M6, especially neurological symptoms related to EFV. Fasting serum lipid profiles improved, but a significant estimated glomerular function rate decrease (−11 mL/min/1.73 m²; P < 10⁻⁴) was observed.

Conclusions. Overall, virologic suppression was maintained in patients after switching to RPV/TDF/ FTC. This STR strategy was associated with improved tolerability.

Drug-drug interactions between anti-retroviral therapies and drugs of abuse in HIV systems

INTRODUCTION

Substance abuse is a common problem among HIV-infected individuals. Importantly, addictions as well as moderate use of alcohol, smoking, or other illicit drugs have been identified as major reasons for non-adherence to antiretroviral therapy (ART) among HIV patients. The literature also suggests a decrease in the response to ART among HIV patients who use these substances, leading to failure to achieve optimal virological response and increased disease progression.

AREAS COVERED

This review discusses the challenges with adherence to ART as well as observed drug interactions and known toxicities with major drugs of abuse, such as alcohol, smoking, methamphetamine, cocaine, marijuana, and opioids. The lack of adherence and drug interactions potentially lead to decreased efficacy of ART drugs and increased ART, and drugs of abuse-mediated toxicity. As CYP is the common pathway in metabolizing both ART and drugs of abuse, we discuss the possible involvement of CYP pathways in such drug interactions.

EXPERT OPINION

We acknowledge that further studies focusing on common metabolic pathways involving CYP and advance research in this area would help to potentially develop novel/alternate interventions and drug dose/regimen adjustments to improve medication outcomes in HIV patients who consume drugs of abuse.