Ritonavir: 25 Years' Experience of Concomitant Medication Management. A Narrative Review.

Ritonavir is a potent inhibitor of the cytochrome P450 3A4 enzyme and is commonly used as a pharmacokinetic (PK) enhancer in antiviral therapies because it increases bioavailability of concomitantly administered antivirals. Decades of experience with ritonavir-enhanced HIV therapies and, more recently, COVID-19 therapies demonstrate that boosting doses of ritonavir are well tolerated, with an established safety profile. The mechanisms of PK enhancement by ritonavir result in the potential for drug-drug interactions (DDIs) with several classes of drugs, thus making co-medication management an important consideration with enhanced antiviral therapies. However, rates of DDIs with contraindicated medications are low, suggesting these risks are manageable by infectious disease specialists who have experience with the use of PK enhancers. In this review, we provide an overview of ritonavir's mechanisms of action and describe approaches and resources available to mitigate adverse events and manage concomitant medication in both chronic and short-term settings.

Evaluating Diversity in Randomized Clinical Trials of Dolutegravir-Based Antiretroviral Therapy Regimens: Pooled 48-Week Analyses by Race, Sex, and Regional Subgroups.

Background: In HIV clinical trials, proportions of Black and female participants achieving virologic suppression (VS) are often lower compared with White and male participants. As the antiretroviral therapy (ART) landscape continues to evolve, addressing existing challenges in clinical trial diversity will be critical to effectively translate results into clinical practice. Here, we pooled data to evaluate the efficacy and safety of dolutegravir (DTG)-containing regimens by race, sex, and regional subgroups. Methods: Three pooled analyses were conducted using 48-week results from phase 3/3b trials: DTG 3-drug vs non-DTG-containing 3- or 4-drug regimens in ART-naive participants (ARIA, FLAMINGO, SINGLE, SPRING-2), DTG-containing 2-drug vs 3-drug regimens in ART-naive participants (GEMINI-1, GEMINI-2), and DTG 3-drug vs non-DTG-containing 3- or 4-drug regimens in ART-experienced participants (SAILING, DAWNING). Proportions of participants with VS, safety, and change from baseline in CD4+ cell count were analyzed. Results: Proportions of participants achieving VS were high among those receiving DTG vs comparator regimens. Proportions of participants achieving VS were generally lower in Black (vs non-Black), female (vs male), and US (vs non-US) subgroups. No new safety signals emerged from any subgroup in pooled analyses. Conclusions: These analyses confirm that, across subgroups, DTG has robust efficacy and a good safety profile at week 48 relative to comparator regimens. Achieving VS may vary by participant characteristics, highlighting the urgent need for enrollment to reflect the demographics of global HIV populations more accurately. Future studies should strive to support participants throughout the trial to ensure optimal representation, inclusion, and retention.

Gag mutations strongly contribute to HIV-1 resistance to protease inhibitors in highly drug-experienced patients besides compensating for fitness loss.

Human immunodeficiency virus type 1 (HIV-1) resistance to protease inhibitors (PI) results from mutations in the viral protease (PR) that reduce PI binding but also decrease viral replicative capacity (RC). Additional mutations compensating for the RC loss subsequently accumulate within PR and in Gag substrate cleavage sites. We examined the respective contribution of mutations in PR and Gag to PI resistance and RC and their interdependence using a panel of HIV-1 molecular clones carrying different sequences from six patients who had failed multiple lines of treatment. Mutations in Gag strongly and directly contributed to PI resistance besides compensating for fitness loss. This effect was essentially carried by the C-terminal region of Gag (containing NC-SP2-p6) with little or no contribution from MA, CA, and SP1. The effect of Gag on resistance depended on the presence of cleavage site mutations A431V or I437V in NC-SP2-p6 and correlated with processing of the NC/SP2 cleavage site. By contrast, reverting the A431V or I437V mutation in these highly evolved sequences had little effect on RC. Mutations in the NC-SP2-p6 region of Gag can be dually selected as compensatory and as direct PI resistance mutations, with cleavage at the NC-SP2 site behaving as a rate-limiting step in PI resistance. Further compensatory mutations render viral RC independent of the A431V or I437V mutations while their effect on resistance persists.

Exploring predictors of HIV-1 virologic failure to long-acting cabotegravir and rilpivirine: a multivariable analysis.

OBJECTIVE: Efficacy and safety of long-acting cabotegravir (CAB) and rilpivirine (RPV) dosed intramuscularly every 4 or 8 weeks has been demonstrated in three Phase 3 trials. Here, factors associated with virologic failure at Week 48 were evaluated post hoc. DESIGN AND METHODS: Data from 1039 adults naive to long-acting CAB+RPV were pooled in a multivariable analysis to examine the influence of baseline viral and participant factors, dosing regimen and drug concentrations on confirmed virologic failure (CVF) occurrence using a logistic regression model. In a separate model, baseline factors statistically associated with CVF were further evaluated to understand CVF risk when present alone or in combination. RESULTS: Overall, 1.25% (n = 13/1039) of participants experienced CVF. Proviral RPV resistance-associated mutations (RAMs), HIV-1 subtype A6/A1, higher BMI (associated with Week 8 CAB trough concentration) and lower Week 8 RPV trough concentrations were significantly associated (P < 0.05) with increased odds of CVF (all except RPV trough are knowable at baseline). Few participants (0.4%) with zero or one baseline factor had CVF. Only a combination of at least two baseline factors (observed in 3.4%; n = 35/1039) was associated with increased CVF risk (25.7%, n = 9/35). CONCLUSION: CVF is an infrequent multifactorial event, with a rate of approximately 1% in the long-acting CAB+RPV arms across Phase 3 studies (FLAIR, ATLAS and ATLAS-2M) through Week 48. Presence of at least two of proviral RPV RAMs, HIV-1 subtype A6/A1 and/or BMI at least 30 kg/m2 was associated with increased CVF risk. These findings support the use of long-acting CAB+RPV in routine clinical practice.

Selective-advantage profile of human immunodeficiency virus type 1 integrase mutants explains in vivo evolution of raltegravir resistance genotypes.

The emergence of human immunodeficiency virus type 1 resistance to raltegravir, an integrase strand transfer inhibitor, follows distinct and independent genetic pathways, among which the N155H and Q148HKR pathways are the most frequently encountered in treated patients. After prolonged viral escape, mutants of the N155H pathway are replaced by mutants of the Q148HKR pathway. We have examined the mechanisms driving this evolutionary pattern using an approach that assesses the selective advantage of site-directed mutant viruses as a function of drug concentration. These selective-advantage curves revealed that among single mutants, N155H had the highest and the widest (1 to 500 nM) selective-advantage profile. Despite the higher 50% inhibitory concentration, Q148H displayed a lower and narrower (10 to 100 nM) selective-advantage profile. Among double mutants, the highest and widest selective-advantage profile was seen with G140S+Q148H. This finding likely explains why N155H can be selected early in the course of RAL resistance evolution in vivo but is later replaced by genotypes that include Q148HKR.

Perspectives on the Barrier to Resistance for Dolutegravir + Lamivudine, a Two-Drug Antiretroviral Therapy for HIV-1 Infection.

In HIV-1-infected patients, virological failure can occur as a consequence of the mutations that accumulate in the viral genome that allow replication to continue in the presence of antiretrovirals (ARVs). The development of treatment-emergent resistance to an ARV can limit a patient's options for future therapy, prompting the need for ARV regimens that are resilient to the emergence of resistance. The genetic barrier to resistance refers to the number of mutations in an ARV's therapeutic target that are required to confer a clinically meaningful loss of susceptibility to the drug. The emergence of resistance can be affected by pharmacological aspects of the ARV, including its structure, inhibitory quotient, therapeutic index, and pharmacokinetic characteristics. Dolutegravir (DTG) has demonstrated a high barrier to resistance, including when used in a two-drug regimen (2DR) with lamivudine (3TC). In the GEMINI-1 and GEMINI-2 studies, DTG +3TC was noninferior to DTG + emtricitabine/tenofovir disoproxil fumarate in treatment-naive participants, with similar proportions achieving HIV-1 RNA <50 copies/mL through 96 weeks. Furthermore, in the TANGO study, virological suppression was maintained at 48 weeks after switching to DTG +3TC from a tenofovir alafenamide (TAF)-based regimen compared with continuing a TAF-based regimen. Most other 2DRs with successful outcomes compared with three-drug regimens have been based on protease inhibitors (PIs); however, this class is associated with adverse metabolic effects and drug-drug interactions. In this review, we discuss the barrier to resistance in the context of a 2DR in which a boosted PI is replaced with DTG +3TC.

Safety and clinical effectiveness of intravitreal administration of bevacizumab (Lumiere®) in patients with neovascular age-related macular degeneration.

The present study was an open-label, prospective, uncontrolled and multicenter clinical trial to investigate the safety and effectiveness of bevacizumab (Lumiere®) administered by the intravitreal route for the treatment of neovascular age-related macular degeneration (nAMD). A total of 22 patients without previous treatment with anti-vascular endothelial growth factor were recruited. Monthly therapy with 1.25 mg intravitreal bevacizumab was applied. Adverse events (AE), visual acuity (VA) and central retinal thickness (CRT) were assessed at baseline, day 1 and day 28 after each injection. A total of 87 AEs were reported; most of them were not serious (96.6%), expected (65.5%) and occurred after the third injection (56.3%). The most frequent AE was 'conjunctival hemorrhage' (29.9% of AEs), attributed to the injection procedure. Treatment was not suspended due to safety reasons in any case. After six months, a statistically significant gain of +8.2 (SD±8.8) letters and a CRT reduction of -75.50 µm (SD±120.3) were achieved with unilateral therapy. VA improvement and CRT reduction were also achieved with bilateral therapy, although to a lesser extent. The results of the present study suggested that therapy with a minimum of 3 doses of bevacizumab over a 6-month period was well tolerated and resulted in a sustained response regarding VA improvement and CRT reduction from the beginning of therapy compared with the baseline value. The study protocol was registered at clinicaltrials.gov (ref. no. NCT03668054).

Prevalence of pretreatment and acquired HIV-1 mutations associated with resistance to lamivudine or rilpivirine: a systematic review.

BACKGROUND: Pretreatment and acquired drug resistance mutations (DRMs) can limit antiretroviral therapy effectiveness. METHODS: We review prevalence of DRMs with resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), focusing on lamivudine and rilpivirine, from 127 articles with >100,000 individuals with HIV-1 infection. RESULTS: Estimated global prevalence of pretreatment resistance to any NRTI was 4% and to any NNRTI was 6%. Most prevalent DRMs resistant to lamivudine or rilpivirine were at positions E138 (4%), V179 (1%) and M184 (1%). Estimated acquired DRM prevalence was 58% for any NRTIs and 67% for any NNRTIs, most frequently at positions M184 (58%) and Y181 (21%). CONCLUSIONS: This review suggests low risk of lamivudine- or rilpivirine-resistant mutations in treatment-naive, HIV-1-infected individuals.

Twenty-Five Years of Lamivudine: Current and Future Use for the Treatment of HIV-1 Infection.

Innovation in medicine is a dynamic, complex, and continuous process that cannot be isolated to a single moment in time. Anniversaries offer opportunities to commemorate crucial discoveries of modern medicine, such as penicillin (1928), polio vaccination (inactivated, 1955; oral, 1961), the surface antigen of the hepatitis B virus (1967), monoclonal antibodies (1975), and the first HIV antiretroviral drugs (zidovudine, 1987). The advent of antiretroviral drugs has had a profound effect on the progress of the epidemiology of HIV infection, transforming a terminal, irreversible disease that caused a global health crisis into a treatable but chronic disease. This result has been driven by the success of antiretroviral drug combinations that include nucleoside reverse transcriptase inhibitors such as lamivudine. Lamivudine, an L-enantiomeric analog of cytosine, potently affects HIV replication by inhibiting viral reverse transcriptase enzymes at concentrations without toxicity against human polymerases. Although lamivudine was approved more than 2 decades ago, it remains a key component of first-line therapy for HIV because of its virological efficacy and ability to be partnered with other antiretroviral agents in traditional and novel combination therapies. The prominence of lamivudine in HIV therapy is highlighted by its incorporation in recent innovative treatment strategies, such as single-tablet regimens that address challenges associated with regimen complexity and treatment adherence and 2-drug regimens being developed to mitigate cumulative drug exposure and toxicities. This review summarizes how the pharmacologic and virologic properties of lamivudine have solidified its role in contemporary HIV therapy and continue to support its use in emerging therapies.

Psychiatric Symptoms in Patients Receiving Dolutegravir.

INTRODUCTION: Psychiatric symptoms (PSs) are reported to occur frequently in people living with HIV and may be associated with specific antiretrovirals. We analyzed PSs observed with dolutegravir (DTG) and other frequently prescribed anchor drugs. METHODS: Selected PSs (insomnia, anxiety, depression, and suicidality) occurring in HIV-positive patients during DTG treatment across 5 randomized clinical trials (3 double-blind), in the Observational Pharmaco-Epidemiology Research & Analysis (OPERA) cohort, and among cases spontaneously reported to ViiV Healthcare were analyzed. RESULTS: In clinical trials, PSs were reported at low and similar rates in patients receiving DTG or comparators [atazanavir, darunavir, efavirenz, or raltegravir (RAL)]. Insomnia was most commonly reported. The highest rates were observed in SINGLE (DTG 17%, efavirenz 12%), with consistently lower rates in the other trials (DTG: 3%-8% versus comparator: 3%-7%). More efavirenz-treated patients withdrew because of PSs than patients treated with other anchor drugs. In OPERA, history of PSs at baseline was lowest in efavirenz-treated patients compared with patients treated with DTG, RAL, or darunavir. Despite baseline differences, prevalence and incidence during treatment were similar across the 4 anchor drugs. Withdrawal rates for PSs were lowest for DTG (0%-0.6%) and highest for RAL (0%-2.5%). Spontaneously reported events were similar in nature to clinical trial data. CONCLUSIONS: Analysis of 3 different data sources shows that, similar to other frequently prescribed anchor drugs to treat HIV infection, PSs are also reported in DTG-treated patients. These events are reported with low frequency and rarely necessitate DTG discontinuation.

Salvage therapy with ritonavir-boosted amprenavir/fosamprenavir: virological and immunological response in two years follow-up.

OBJECTIVE: To evaluate the efficacy of salvage regimens containing ritonavir-boosted amprenavir (APV/r) or fosamprenavir (FPV/r) in heavily pretreated protease inhibitor (PI)-experienced HIV-1 patients. METHOD: Evaluation of APV/r- or FPV/r-containing antiretroviral regimens in PI-experienced HIV-1 patients with 2 or more antiretroviral failures. Follow-up continued to 96 weeks with prospective collection of data. RESULTS: 54 episodes (48 on APV/r and 6 on FPV/r) were considered in 45 patients who had received a median of 5 prior antiretroviral regimens (range, 2-13) including a median of 3 PIs (range, 2-4). Median time of treatment at analysis was 72 weeks (range, 12-210). At baseline, plasma viral load (pVL) and CD4 cell count was 67,000 copies/mL and 167 cell/mm(3), respectively. At week 96, the median pVL was < 50 copies/mL and CD4 cell count was 519 cells/mm(3). Proportion of patients with pVL below detection was 62% at week 48 and 61% at week 96. Fifteen patients stopped treatment because of virologic failure; one presented a full resistance profile to APV/r, based on the ANRS 2003 resistance algorithm. Median trough APV plasma concentration 4 weeks after treatment initiation was 1406 ng/mL (range, 452-4321); dose adaptation was required in only 7 patients. CONCLUSION: This study provides long-term follow-up of APV/r and FPV/r in the setting of salvage therapy, showing a high and sustained rate of virologic and immunologic response.

Comparative changes of lipid levels in treatment-naive, HIV-1-infected adults treated with dolutegravir vs. efavirenz, raltegravir, and ritonavir-boosted darunavir-based regimens over 48 weeks.

BACKGROUND AND OBJECTIVES: Long-term use of antiretroviral therapy (ART) to treat HIV infection has been associated with dyslipidemia and metabolic and cardiovascular complications. Available options for patients at risk of cardiovascular disease include antiretroviral drugs with improved lipid profiles. Dolutegravir is one of a new generation of HIV integrase inhibitors recently incorporated into the US Department of Health and Human Services, German, Spanish, and Italian HIV treatment guidelines as a preferred first-line third agent in combination with dual nucleoside reverse transcriptase inhibitor (NRTI) backbone therapies. To understand the lipid profile of dolutegravir in the context of combination ART, we analyzed the lipid outcomes at 48 weeks in ART-naive participants in four phase IIb-IIIb clinical trials. METHODS: Variables included in this analysis were total cholesterol (TC), low-density lipoprotein (LDL) cholesterol (LDL-C), high-density lipoprotein (HDL) cholesterol (HDL-C), TC/HDL ratio, and triglycerides at baseline and week 48. RESULTS: In a comparative analysis, dolutegravir demonstrated a broadly neutral effect on lipids versus efavirenz or ritonavir-boosted darunavir; in both comparisons, patients taking dolutegravir exhibited smaller increases in TC, LDL-C, and triglyceride levels. In comparison with raltegravir, dolutegravir exhibited a similar lipid profile, including small increases in TC, LDL-C, and triglyceride levels for both agents. In the pooled dolutegravir analysis, minimal increases in LDL-C and triglycerides were observed but mean values at 48 weeks remained below National Cholesterol Education Program target levels. HDL-C levels increased at 48 weeks, and the mean TC/HDL-C ratio was 0.6 at 48 weeks; these values are associated with a lower risk of cardiovascular disease. CONCLUSIONS: Together, these data show that dolutegravir has a safer lipid profile in combination ART and provides an important treatment option for older patients who may have other risk factors for metabolic syndrome or cardiovascular disease.

Immunological responses and long-term treatment interruption after human immunodeficiency virus type 1 (HIV-1) lipopeptide immunization of HIV-1-infected patients: the LIPTHERA study.

We studied the time course of immunological and virological markers after highly active antiretroviral therapy (HAART) interruption in chronically human immunodeficiency virus type 1 (HIV-1)-infected patients immunized with an HIV lipopeptide preparation. In a prospective open pilot study, 24 HIV-1-infected HAART-treated patients with undetectable plasma viral loads (pVLs) and CD4(+) T-cell counts above 350/mm(3) were immunized at weeks 0, 3, and 6 with a candidate vaccine consisting of six HIV lipopeptides. At week 24, patients with pVLs of <1.7 log(10) copies/ml were invited to stop taking HAART. Antiretroviral therapy was resumed if the pVL rose above 4.47 log(10) copies/ml and/or if the CD4(+) cell count fell below 250/mm(3). Immunological and virologic parameters were studied before and after HAART interruption. The median baseline and nadir CD4(+) cell counts were 482 (interquartile range [IQR], 195 to 826) and 313 (IQR, 1 to 481)/mm(3), respectively. New specific CD8(+) cell responses to HIV-1 epitopes were detected after immunization in 13 (57%) of 23 assessable patients. Twenty-one patients were evaluated 96 weeks after HAART interruption. The median time to pVL rebound was 4 weeks (IQR, 2 to 6), and the median peak pVL was 4.26 (IQR, 3 to 5) log(10) copies/ml. Thirteen of these 21 patients resumed HAART a median of 60 weeks after immunization (IQR, 9.2 to 68.4 weeks), when the median pVL was 4.8 (IQR, 2.9 to 5.7) log(10) copies/ml and the median CD4(+) cell count was 551 (IQR, 156 to 778)/mm(3). Eight patients were still off therapy at 96 weeks, with a median pVL of 4 (IQR, 1.7 to 4.6) log(10) copies/ml and a median CD4(+) cell count of 412 (IQR, 299 to 832)/mm(3). No clinical disease progression had occurred. Despite the lack of a control arm, these findings warrant a randomized study of therapeutic vaccination with HIV lipopeptides followed by long-term HAART interruption in AIDS-free chronically infected patients.

Higher baseline levels of plasma human immunodeficiency virus type 1 RNA are associated with increased mortality after initiation of triple-drug antiretroviral therapy.

We evaluated 1422 antiretroviral therapy (ART)-naive patients infected with human immunodeficiency virus (HIV) who initiated highly active antiretroviral therapy between 1 August 1 1996 and 31 July 2000 and were monitored until 31 March 2002. Patients were stratified on the basis of baseline levels of HIV RNA (<50,000, 50,000-99,999, and > or =100,000 copies/mL). Cox regression was used to determine independent predictors of time to death. After adjustment for adherence to ART and other potential confounders, baseline levels of HIV RNA of > or =100,000 copies/mL remained independently associated with mortality (adjusted relative hazard, 1.71; 95% confidence interval, 1.08-2.70; P=.023). If appropriately confirmed, these findings have important implications for the development of therapeutic guidelines.