Outcome of Darunavir-Cobicistat-Based Regimens in HIV-Infected People Who Have Experienced Virological Failure

Objective

To evaluate the virological outcome of darunavir-cobicistat (DRVc)-based regimens in adults living with HIV who had experienced virological failure (VF) on any previous drug combination.

Methods

This was a retrospective cohort study (CSLHIV Cohort) of adults living with HIV who started a DRVc-based regimen with HIV-RNA >50 copies/mL after VF on any previous drug combination. Data on demographics, antiretroviral treatment since HIV diagnosis, and immunological and metabolic parameters from baseline (start of DRVc) to 48 weeks were analyzed in order to assess the cumulative proportion of those who achieved virological success (VS), defined as at least one instance of HIV-RNA <50 copies/mL within 12 months from baseline. Follow-up lasted from the start of the DRVc-based regimen (baseline) to the first instance of HIV-RNA <50 copies/mL, last available visit, or loss to follow-up or death, whichever occurred first. Univariate and multivariate Cox proportional-hazard regression models were used to identify baseline factors associated with VS.

Results

A total of 176 individuals were included, and 120 (68.2%) achieved <50 HIV-RNA copies/mL within 12 months since baseline. On multivariate analysis, baseline HDL cholesterol was independently associated with the occurrence of VS (adjusted HR 1.021, 95% CI 1.004-1.038; p=0.014). Among the 120 subjects with VS, 27 (22.5%) had had VF during a median follow-up of 20.8 months since the first undetectable HIV-RNA. Resistance testing after VF was available in two cases, which harboured the HIV variant-bearing protease inhibitor-resistance mutations D30N, I50V, and N88D. During a median follow-up of 38.4 months, 65 of 176 (36.9%) individuals discontinued DRVc for any reason (37 of 120, 30.8%) and achieved VS vs. 28 of 56 (50%) without VS (p=0.019). Time to discontinuation was longer in people with VS (41.5 vs. 23.0 months, p=0.0007). No statistically significant changes were observed in immunological or lipid profiles during follow-up.

Conclusion

Most individuals in this study achieved VS within 12 months from the beginning of a DRVc-based regimen; therefore, this treatment represent a viable option for people who have experienced VF on other regimens.

Unveiling drug induced nephrotoxicity using novel biomarkers and cutting-edge preventive strategies

Drug-induced nephrotoxicity is still a significant obstacle in pharmacotherapy of various diseases and it accounts for around 25 % of serious side-effects reported after drug administration. Furthermore, some groups of drugs such as nonsteroidal anti-inflammatory drugs, antibiotics, antiviral drugs, antifungal drugs, immunosuppressants, and chemotherapeutic drugs have the "preference" for damaging the kidney and are often referred to as the kidney's "silent killer". Clinically, the onset of acute kidney injury associated with drug administration is registered in approximately 20 % of patients and many of them develop chronic kidney disease vulnerability. However, current knowledge about the mechanisms underlying this dangerous phenomenon is still insufficient with many unknowns. Hence, the valuable use of these drugs in clinical practice is significantly limited. The main aim of this study is to draw attention to commonly prescribed nephrotoxic drugs by clinicians or drugs bought over the counter. In addition, the complex relationship between immunological, vascular and inflammatory events that promote kidney damage is discussed. The practical use of this knowledge could be implemented in the engineering of novel biomarkers for early detection of drug-associated kidney damage such as Kidney Injury Molecule (KIM-1), lipocalin associated with neutrophil gelatinase (NGAL) and various microRNAs. In addition, the utilization of artificial intelligence (AI) for the development of computer algorithms that could detect kidney damage at an early stage should be further explored. Therefore, this comprehensive review provides a new outlook on drug nephrotoxicity that opens the door for further clinical research of novel potential drugs or natural products for the prevention of drug-induced nephrotoxicity and accessible education.

Discontinuation of tenofovir disoproxil fumarate from initial ART regimens because of renal adverse events: An analysis of data from four multi-country clinical trials

Tenofovir disoproxil fumarate (TDF), a potent and commonly used antiretroviral drug, is associated with renal tubular dysfunction and renal adverse events. We evaluated the frequency of, time to, and baseline risk factors for discontinuing TDF from initial antiretroviral therapy (ART) regimens because of renal adverse events from presumed tenofovir renal toxicity. We conducted an observational cohort study as a secondary analysis of data from four clinical trials conducted mainly in low- and middle-income countries. We included ART naïve participants living with HIV who started TDF-containing ART regimens in the trials. Participants had to have estimated creatinine clearance (eCrCl) equal to or greater than 60ml/min before starting ART. The primary outcome was the first instance of discontinuing TDF because of renal adverse events attributed to tenofovir renal toxicity during the first 48 weeks after starting ART. We evaluated the cumulative incidence of discontinuing TDF and associated risk factors using Fine and Gray competing risk regression models with a backward elimination variable selection strategy. There were 2802 ART-naïve participants who started TDF-containing ART from the four clinical trials were included in the analysis. Fifty-eight percent were female, the median age was 34 years, and 87% had CD4 cell counts less than 200 cells/μl. Sixty-four participants (2.4%, 95% CI 1.7%-2.8%) discontinued TDF due to renal adverse events. Among the 64 participants, the median time to discontinue TDF was 9.4 weeks (IQR: 3.4-20.7 weeks). From multivariable Fine and Gray regression models, risk factors for discontinuing TDF were older age, CD4 cell count <200 cells/μl, presence and severity of anemia, and eCrCl <90 ml/min. The risk of discontinuing TDF because of renal adverse events was low in participants initiating TDF-containing ART with advanced HIV and normal renal function, attesting to the tolerability of TDF in ART in low- and middle-income countries.

Synthesis and characterization of two known and one new impurities of dolutegravir: In silico evaluation of certain intermediates against SARS CoV-2 O-ribose methyltransferase (OMTase)

Besides its use against HIV infection the marketed anti-retroviral drug dolutegravir attracted attention as a potential agent against COVID-19 in multiple AI (artificial intelligence) based studies. Due to our interest in accessing the impurities of this drug we report the synthesis and characterization of three impurities of dolutegravir one of which is new. The synthesis of O-methyl ent-dolutegravir was accomplished in three-steps the first one involved the construction of fused 1,3-oxazinane ring. The cleavage of -OEt ether moiety followed by methylation afforded the target compound. The second impurity i.e. N-(2,4-difluorobenzyl)-4-methoxy-3-oxobutanamide was synthesized via a multi-step method involving sequentially the keto group protection, ester hydrolysis, acid chloride formation followed by the reaction with amine and finally keto group deprotection. The synthesis of new or dimer impurity was carried out via another multi-step method similar to the previous one starting from ethyl 4-chloro acetoacetate. The methodology involved preparation of ether derivative, keto group protection, ester hydrolysis, preparation of amide derivative via acid chloride formation in situ and then keto group deprotection for a longer duration. The last step afforded the target compound for which a plausible reaction mechanism has been proposed. All three impurities were prepared in gram scale (minimum 2 g and maximum 8 g). The in silico evaluation of three selected synthesized intermediates e.g. 7, 8 and 9 (structurally similar to dolutegravir) against SARS CoV-2 O-ribose methyltransferase (OMTase) (PDB: 3R24) indicated that compound 7 could be of interest as a possible inhibitor of this protein.

A clinical review of HIV integrase strand transfer inhibitors (INSTIs) for the prevention and treatment of HIV-1 infection

Integrase strand transfer inhibitors (INSTIs) have improved the treatment of human immunodeficiency virus (HIV). There are currently four approved for use in treatment-naïve individuals living with HIV; these include first generation raltegravir, elvitegravir, and second generation dolutegravir and bictegravir. The most recent INSTI, cabotegravir, is approved for (1) treatment of HIV infection in adults to replace current antiretroviral therapy in individuals who maintain virologic suppression on a stable antiretroviral regimen without history of treatment failure and no known resistance to its components and (2) pre-exposure prophylaxis in individuals at risk of acquiring HIV-1 infection. Cabotegravir can be administered intramuscularly as a monthly or bi-monthly injection depending on the indication. This long-acting combination has been associated with treatment satisfaction in clinical studies and may be helpful for individuals who have difficulty taking daily oral medications. Worldwide, second generation INSTIs are preferred for treatment-naïve individuals. Advantages of these INSTIs include their high genetic barrier to resistance, limited drug-drug interactions, excellent rates of virologic suppression, and favorable tolerability. Few INSTI resistance-associated mutations have been reported in clinical trials involving dolutegravir, bictegravir and cabotegravir. Other advantages of specific INSTIs include their use in various populations such as infants and children, acute HIV infection, and individuals of childbearing potential. The most common adverse events observed in clinical studies involving INSTIs included diarrhea, nausea, insomnia, fatigue, and headache, with very low rates of treatment discontinuation versus comparator groups. The long-term clinical implications of weight gain associated with second generation INSTIs dolutegravir and bictegravir warrants further study. This review summarizes key clinical considerations of INSTIs in terms of clinical pharmacology, drug-drug interactions, resistance, and provides perspective on clinical decision-making. Additionally, we summarize major clinical trials evaluating the efficacy and safety of INSTIs in treatment-naïve patients living with HIV as well as individuals at risk of acquiring HIV infection.

Phenotypic resistance to lenacapavir and monotherapy efficacy in a proof-of-concept clinical study

BACKGROUND

Lenacapavir in vitro resistance selections identified seven mutations in HIV-1 capsid protein (CA) associated with reduced susceptibility.

OBJECTIVES

To analyse lenacapavir activity against lenacapavir-associated resistance mutations in multiple assays. We also report Day 10 resistance analyses conducted in a Phase 1b study of lenacapavir (Study 4072) in people with HIV (PWH).

METHODS

Mutations were inserted in a proviral DNA clone by site-directed mutagenesis, and viruses (n = 12) were generated by transfection. Sequences were used to generate single-cycle (SC) test vectors that were evaluated in a Gag-Pro assay, and replicative viruses were tested in a multicycle (MC) MT-2 assay to determine lenacapavir susceptibility. Study 4072 was a Phase 1b, double-blinded, placebo-controlled, dose-ranging, randomized study of lenacapavir in untreated PWH. Participants received a single dose of lenacapavir (up to 750 mg) or placebo (10 day monotherapy). CA resistance was characterized using genotypic and/or phenotypic assays.

RESULTS

Lenacapavir susceptibility in the SC assay showed an inverse relationship between replication capacity and resistance. In Study 4072, all 29 participants receiving lenacapavir showed a robust virological response with no rebound. At baseline, no participant had resistance mutations to lenacapavir, and all had WT susceptibility to lenacapavir. Post-monotherapy analyses revealed the emergence of CA mutation Q67H at Day 10 in two participants.

CONCLUSIONS

In vitro assays confirmed that increased resistance to lenacapavir was associated with decreased replication capacity of mutant viruses. In the clinical study no pre-existing lenacapavir resistance was detected. Emergence of Q67H occurred at exposures below the dose used in current Phase 2/3 studies. These results support development of lenacapavir as an antiretroviral agent.

Summary of 2021 Clinical Guidelines for the Diagnosis and Treatment of HIV/AIDS in HIV-infected Koreans

Since the establishment of the Committee for Clinical Guidelines for the Diagnosis and Treatment of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) by the Korean Society for AIDS in 2010, clinical guidelines have been prepared in 2011, 2013, 2015, and 2018. As new research findings on the epidemiology, diagnosis, and treatment of AIDS have been published in and outside of Korea along with the development and introduction of new antiretroviral medications, a need has arisen to revise the clinical guidelines by analyzing such new data. The clinical guidelines address the initial evaluation of patients diagnosed with HIV/AIDS, follow-up tests, appropriate timing of medication, appropriate antiretroviral medications, treatment strategies for patients who have concurrent infections with hepatitis B or C virus, recommendations for resistance testing, treatment for patients with HIV and tuberculosis coinfections, and treatment in pregnant women. Through these clinical guidelines, the Korean Society for AIDS and the Committee for Clinical Guidelines for the Diagnosis and Treatment of HIV/AIDS contributes to overcoming AIDS by delivering latest data and treatment strategies to healthcare professionals who treat AIDS in the clinic.

Preparation of the Key Dolutegravir Intermediate via MgBr2-Promoted Cyclization

A novel approach for synthesizing the key dolutegravir intermediate is described via MgBr₂-promoted intramolecular cyclization. Condensation of commercially available methyl oxalyl chloride and ethyl 3-(N,N-dimethylamino)acrylate afforded the vinylogous amide in an excellent yield. Subsequent substitution by aminoacetaldehyde dimethyl acetal and methyl bromoacetate gave rise to the expected precursor for cyclization, which was promoted by MgBr₂ to highly selectively convert into pyridinone diester. The key dolutegravir intermediate was finally prepared by the selective hydrolysis of the corresponding diester via LiOH.

Week 96 subgroup analyses of the phase 3, randomized AMBER and EMERALD trials evaluating the efficacy and safety of the once daily darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) single-tablet regimen in antiretroviral treatment (ART)-naïve and -experienced, virologically-suppressed adults living with HIV-1

BACKGROUND

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated in AMBER (treatment-naïve adults; NCT02431247) and EMERALD (treatment-experienced, virologically-suppressed adults; NCT02269917).

OBJECTIVE

To describe a Week 96 pre-planned subgroup analysis of D/C/F/TAF arms by demographic characteristics (age ≤/>50 years, gender, black/non-black race), and baseline clinical characteristics (AMBER: viral load [VL], CD4⁺ count, WHO clinical stage, HIV-1 subtype and antiretroviral resistance; EMERALD: prior virologic failure [VF], antiretroviral experience, screening boosted protease inhibitor [PI], and boosting agent).

METHODS

Patients in D/C/F/TAF and control arms could continue on/switch to D/C/F/TAF in a single-arm, open-label extension phase after Week 48 until Week 96. Efficacy endpoints were percentage cumulative confirmed VL ≥50 copies/mL (virologic rebound; EMERALD), and VL <50 (virologic response), or ≥50 copies/mL (VF) (FDA snapshot; both trials).

RESULTS

D/C/F/TAF demonstrated high Week 96 virologic responses (AMBER: 85% [308/362]; EMERALD: 91% [692/763]) and low VF rates (AMBER: 6% [20/362]; EMERALD: 1% [9/763]). In EMERALD, D/C/F/TAF showed low virologic rebound cumulative through Week 96 (3% [24/763]). Results were consistent across subgroups, including prior antiretroviral experience in EMERALD. No darunavir, primary PI, or tenofovir resistance-associated mutations were observed post-baseline. Study-drug-related serious adverse events (AEs) and AE-related discontinuations were <1% and 2%, respectively (both D/C/F/TAF arms), and similar across subgroups. eGFR_cyst and bone mineral density improved or were stable and lipids increased through Week 96 across demographic subgroups, with small changes in total-cholesterol/HDL-cholesterol ratio.

CONCLUSIONS

D/C/F/TAF was effective with a high barrier to resistance and bone/renal safety benefits, regardless of demographic or clinical characteristics for treatment-naïve and treatment-experienced, virologically-suppressed adults.

An Overview of the Synthesis and Antimicrobial, Antiprotozoal, and Antitumor Activity of Thiazole and Bisthiazole Derivatives

Thiazole, a five-membered heteroaromatic ring, is an important scaffold of a large number of synthetic compounds. Its diverse pharmacological activity is reflected in many clinically approved thiazole-containing molecules, with an extensive range of biological activities, such as antibacterial, antifungal, antiviral, antihelmintic, antitumor, and anti-inflammatory effects. Due to its significance in the field of medicinal chemistry, numerous biologically active thiazole and bisthiazole derivatives have been reported in the scientific literature. The current review provides an overview of different methods for the synthesis of thiazole and bisthiazole derivatives and describes various compounds bearing a thiazole and bisthiazole moiety possessing antibacterial, antifungal, antiprotozoal, and antitumor activity, encouraging further research on the discovery of thiazole-containing drugs.

Week 96 results of a phase 3 trial of darunavir/cobicistat/emtricitabine/tenofovir alafenamide in treatment-naive HIV-1 patients

BACKGROUND

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated through 96 weeks in AMBER (NCT02431247).

METHODS

Treatment-naive, HIV-1-positive adults [screening plasma viral load ≥1000 copies/ml; CD4 cell count >50 cells/μl) were randomized (1 : 1) to D/C/F/TAF (N = 362) or D/C plus emtricitabine/tenofovir-disoproxil-fumarate (F/TDF) (N = 363) over at least 48 weeks. After week 48, patients could continue on or switch to D/C/F/TAF in an open-label extension phase until week 96.

RESULTS

At week 96, D/C/F/TAF exposure was 626 patient-years (D/C/F/TAF arm) and 109 patient-years (control arm post switch), week 96 virologic suppression (viral load <50 copies/ml; FDA-Snapshot, from baseline) was 85.1% (308/362) (D/C/F/TAF) and 83.7% (304/363) (control). Week 96 virologic failure (viral load ≥50 copies/ml; FDA-Snapshot) was 5.5% (20/362) and 4.4% (16/363), respectively. No darunavir, primary protease inhibitor or tenofovir resistance-associated mutations (RAMs) were observed post baseline. In one patient in each arm, an M184I and/or V RAM was detected. Few adverse event-related discontinuations (3% D/C/F/TAF; <1% control post switch) and no deaths occurred on D/C/F/TAF. Improved renal and bone parameters were maintained in the D/C/F/TAF arm and observed in the control arm post switch. Increases in total-cholesterol/high-density-lipoprotein--cholesterol rtio at week 96 were +0.25 versus baseline (D/C/F/TAF) and +0.24 versus switch (control).

CONCLUSION

At week 96, D/C/F/TAF resulted in high virologic response and low virologic failure rates, with no resistance development to darunavir or TAF/TDF. Bone, renal and lipid safety were consistent with known D/C/F/TAF component profiles. Control arm safety post switch was consistent with the D/C/F/TAF arm. AMBER week 96 results confirm the efficacy, high barrier to resistance and bone/renal safety benefits of D/C/F/TAF for treatment-naive patients.

Optimizing antiretroviral regimens in chronic kidney disease

PURPOSE OF REVIEW

To identify recent data that inform the management of individuals with HIV and chronic kidney disease.

RECENT FINDINGS

Several nonnucleoside reverse transcriptase, protease, and integrase strand transfer inhibitors inhibit tubular creatinine secretion resulting in stable reductions in creatinine clearance of 5-20 ml/min in the absence of other manifestations of kidney injury. Progressive renal tubular dysfunction is observed with tenofovir disoproxil fumarate in clinical trials, and more rapid decline in estimated glomerular filtration rate in cohort studies of tenofovir disoproxil fumarate and atazanavir, with stabilization, improvement or recovery of kidney function upon discontinuation. Results from clinical trials of tenofovir alafenamide (TAF) in individuals with chronic kidney disease suggest that TAF is well tolerated in those with mild to moderate renal impairment (creatinine clearance >30 ml/min) but results in very high tenofovir exposures in those on haemodialysis.

SUMMARY

Standard antiretroviral regimens remain appropriate for individuals with normal and/or stable, mildly impaired kidney function. In those with chronic kidney disease or progressive decline in estimated glomerular filtration rate, antiretrovirals with nephrotoxic potential should be avoided or discontinued. Although TAF provides a tenofovir formulation for individuals with impaired kidney function, TAF is best avoided in those with severe or end-stage kidney disease.

Assessing bias introduced in estimated glomerular filtration rate by the inhibition of creatinine tubular secretion from common antiretrovirals

BACKGROUND

Researchers must often rely on creatinine measurements to assess kidney function because direct glomerular filtration rates (GFR) and cystatin-c are rarely measured in routine clinical settings. However, HIV treatments often include dolutegravir, raltegravir, rilpivirine or cobicistat, which inhibit the proximal tubular secretion of creatinine without impairing kidney function, thus leading to measurement bias when using creatinine-based estimated GFR (eGFR). We developed eGFR correction factors to account for this potential bias.

METHODS

11,359 treatment-naive HIV-positive individuals in OPERA were included if they initiated dolutegravir, elvitegravir/cobicistat, darunavir/cobicistat, raltegravir, rilpivirine or efavirenz (control) with an eGFR >60 ml/min/1.73 m². The eGFR was corrected by adding the median decrease reported in the literature to the calculated eGFR; correction factors were not validated. Incidence rates of eGFR <60 ml/min/1.73 m² (Poisson regression) and the relationship between regimens and eGFR <60 ml/min/1.73 m² (multivariate Cox proportional hazards models) were estimated with and without eGFR correction.

RESULTS

Without eGFR correction, dolutegravir, elvitegravir/cobicistat, darunavir/cobicistat, raltegravir and rilpivirine based regimens were statistically significantly associated with a higher likelihood of eGFR <60 ml/min/1.73 m² than efavirenz. With eGFR correction, each of these regimens was associated with a statistically significantly lower likelihood of eGFR <60 ml/min/1.73 m² compared with efavirenz.

CONCLUSIONS

With increasing use of agents that inhibit tubular creatinine secretion, artificially low eGFR values could lead to erroneous conclusions in studies of HIV treatment and kidney outcomes measured with creatinine-based eGFR equations. Sensitivity analyses assessing the potential magnitude of bias arising from creatinine secretion inhibition should be performed.

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.

Renal safety of tenofovir alafenamide vs. tenofovir disoproxil fumarate: a pooled analysis of 26 clinical trials

Supplemental Digital Content is available in the text

Objective:

Compared with tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF) has been associated with improvement in markers of renal dysfunction in individual randomized trials; however, the comparative incidence of clinically significant renal events remains unclear.

Design:

We used a pooled data approach to increase the person-years of drug exposure analysed, maximizing our ability to detect differences in clinically significant outcomes.

Methods:

We pooled clinical renal safety data across 26 treatment-naive and antiretroviral switch studies to compare the incidence of proximal renal tubulopathy and discontinuation due to renal adverse events between participants taking TAF-containing regimens vs. those taking TDF-containing regimens. We performed secondary analyses from seven large randomized studies (two treatment-naive and five switch studies) to compare incidence of renal adverse events, treatment-emergent proteinuria, changes in serum creatinine, creatinine clearance, and urinary biomarkers (albumin, beta-2-microglobulin, and retinol binding protein-to-creatinine ratios).

Results:

Our integrated analysis included 9322 adults and children with HIV (n = 6360 TAF, n = 2962 TDF) with exposure of 12 519 person-years to TAF and 5947 to TDF. There were no cases of proximal renal tubulopathy in participants receiving TAF vs. 10 cases in those receiving TDF (P < 0.001), and fewer individuals on TAF (3/6360) vs. TDF (14/2962) (P < 0.001) discontinued due to a renal adverse event. Participants initiating TAF-based vs. TDF-based regimens had more favourable changes in renal biomarkers through 96 weeks of therapy.

Conclusion:

These pooled data from 26 studies, with over 12 500 person-years of follow-up in children and adults, support the comparative renal safety of TAF over TDF.

Atazanavir Plus Cobicistat: Week 48 and Week 144 Subgroup Analyses of a Phase 3, Randomized, Double-Blind, Active-Controlled Trial

OBJECTIVES

Cobicistat (COBI) enhances atazanavir (ATV) pharmacokinetic parameters similarly to ritonavir (RTV) in both healthy volunteers and HIV-infected adults. Primary efficacy and safety outcomes of this Phase 3, international, randomized, double-blind, double-dummy, active- controlled trial in HIV-1-infected treatment-naïve adults (GS-US-216-0114/NCT01108510) demonstrated that ATV+COBI was non-inferior to ATV+RTV, each in combination with emtricitabine/ tenofovir disoproxil fumarate (FTC/TDF), at Weeks 48 and 144, with high rates of virologic success for both regimens (85.2% and 87.4%, respectively, at Week 48; and 72.1% and 74.1% at Week 144), and with comparable safety and tolerability. Here, we describe virologic response and treatment discontinuation by a wider range of subgroups than previously presented.

METHODS

Subgroup analyses by baseline CD4 count (≤200, 201-350, &gt;350 cells/mm3), baseline HIV-1 RNA level (≤100,000, &gt;100,000 copies/mL), race, sex, and age (&lt;40, ≥40 years) evaluated ATV+COBI versus ATV+RTV univariate odds ratios (ORs) for virologic success (viral load &lt;50 copies/mL, intention-to-treat US Food and Drug Administration Snapshot algorithm) and discontinuation due to adverse events (AEs) at Weeks 48 and 144. Of 692 patients randomized, 344 received ATV+COBI and 348 ATV+RTV.

RESULTS

ATV+COBI versus ATV+RTV ORs for virologic success did not significantly differ by regimen overall at Weeks 48 and 144 (OR 0.90; 95% confidence interval [CI]: 0.64, 1.26) or within subgroups, except in females, for whom ATV+COBI was favored at Week 144 (OR 2.36; 95% CI: 1.02, 5.47). However, there were more discontinuations due to withdrawal of consent and pregnancies in females receiving ATV+RTV versus ATV+COBI. ORs for discontinuation due to AEs did not significantly differ by regimen overall at Weeks 48 and 144 (OR 0.98; 95% CI: 0.61, 1.58) or within subgroups.

CONCLUSION

These findings indicate that both ATV+COBI and ATV+RTV, each with FTC/TDF, are effective and well-tolerated treatment options across a wide demographic range of HIV-infected patients.

Race/ethnicity difference in the pharmacogenetics of bilirubin-related atazanavir discontinuation

BACKGROUND

Atazanavir causes plasma indirect bilirubin to increase. We evaluated associations between Gilbert's polymorphism and bilirubin-related atazanavir discontinuation stratified by race/ethnicity.

PATIENTS AND METHODS

Patients had initiated atazanavir/ritonavir-containing regimens at an HIV primary care clinic in the southeastern USA, and had at least 12 months of follow-up data. Metabolizer group was defined by UGT1A1 rs887829 C→T. Genome-wide genotype data were used to adjust for genetic ancestry in combined population analyses.

RESULTS

Among 321 evaluable patients, 15 (4.6%) had bilirubin-related atazanavir discontinuation within 12 months. Homozygosity for rs887829 T/T was present in 28.1% of Black, 21.4% of Hispanic, and 8.6% of White patients. Among all patients the hazard ratio (HR) for bilirubin-related discontinuation with T/T versus C/C genotype was 7.3 [95% confidence interval (CI): 1.7-31.5; P=0.007]. Among 152 White patients the HR was 14.4 (95% CI: 2.6-78.7; P=0.002), but among 153 Black patients the HR was 0.8 (95% CI: 0.05-12.7; P=0.87).

CONCLUSION

Among patients who initiated atazanavir/ritonavir-containing regimens, UGT1A1 slow metabolizer genotype rs887829 T/T was associated with increased bilirubin-related discontinuation of atazanavir in White but not in Black patients, this despite T/T genotype being more frequent in Black patients.

Strength in Amalgamation: Newer Combination Agents for HIV and Implications for Practice

Antiretroviral (ART) therapy for the treatment of human immunodeficiency virus (HIV) infection has undergone significant changes over the past 30 years. Many single-tablet regimens (STRs), including newer fixed-dose combination (FDC) tablets, are available, offering patients several options for choosing a treatment regimen that works best for them. Given these changes, patients are more likely to adhere to treatment, achieve better clinical outcomes, and experience both fewer side effects and drug-drug interactions. Newer STRs include dolutegravir (DTG)/lamivudine (3TC)/abacavir (ABC) (Triumeq; Viiv Healthcare, Research Triangle Park, NC), rilpivirine (RPV)/emtricitabine (FTC)/tenofovir alafenamide (TAF) (Odefsey; Gilead, Foster City, CA), RPV/FTC/tenofovir disoproxil fumarate (TDF) (Complera; Gilead), elvitegravir (EVG)/cobicistat (COBI)/FTC/TDF (Stribild; Gilead), and EVG/COBI/FTC/TAF (Genvoya; Gilead). Recently approved FDCs, such as atazanavir (ATV)/COBI (Evotaz; Bristol-Myers Squibb, Princeton, NJ), darunavir (DRV)/COBI (Prezcobix; Janssen Products, Titusville NJ), and FTC/TAF (Descovy; Gilead), are also now available. The Department of Health and Human Services treatment guidelines for HIV recommend many of these integrase strand transfer inhibitor (INSTI) STRs as a preferred choice for initiation of treatment in both ART-naive and -experienced patients because they offer comparably faster rates of virologic suppression, reduced rates of resistance development (especially with DTG), and overall better adherence than protease inhibitors or NNRTIs. Numerous phase 3 clinical trials support these recommendations including several switch or simplification clinical trials. Notably, the novel pharmacokinetic booster COBI, with its water soluble properties, has enabled the development and coformulation of a few of these STRs and FDCs. Also, a newer tenofovir salt formulation, TAF, has an advantageous pharmacokinetic profile, contributing to better overall renal and bone tolerability compared with TDF. Further simplification regimens comprising dual ART therapies are currently being explored. This review provides an overview of the clinical efficacy and safety data for these coformulated agents, highlighting the relative impact on comparative adverse events, assessing the potential for experiencing fewer drug-drug interactions, and discussing the clinical implications regarding adherence to treatment.

Cobicistat Versus Ritonavir: Similar Pharmacokinetic Enhancers But Some Important Differences

OBJECTIVE

To describe properties of cobicistat and ritonavir; compare boosting data with atazanavir, darunavir, and elvitegravir; and summarize antiretroviral and comedication interaction studies, with a focus on similarities and differences between ritonavir and cobicistat. Considerations when switching from one booster to another are discussed.

DATA SOURCES

A literature search of MEDLINE was performed (1985 to April 2017) using the following search terms: cobicistat, ritonavir, pharmacokinetic, drug interactions, booster, pharmacokinetic enhancer, HIV, antiretrovirals. Abstracts from conferences, article bibliographies, and product monographs were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Relevant English-language studies or those conducted in humans were considered.

DATA SYNTHESIS

Similar exposures of elvitegravir, darunavir, and atazanavir are achieved when combined with cobicistat or ritonavir. Cobicistat may not be as potent a CYP3A4 inhibitor as ritonavir in the presence of a concomitant inducer. Ritonavir induces CYP1A2, 2B6, 2C9, 2C19, and uridine 5'-diphospho-glucuronosyltransferase, whereas cobicistat does not. Therefore, recommendations for cobicistat with comedications that are extrapolated from studies using ritonavir may not be valid. Pharmacokinetic properties of the boosted antiretroviral can also affect interaction outcome with comedications. Problems can arise when switching patients from ritonavir to cobicistat regimens, particularly with medications that have a narrow therapeutic index such as warfarin.

CONCLUSIONS

When assessing and managing potential interactions with ritonavir- or cobicistat-based regimens, clinicians need to be aware of important differences and distinctions between these agents. This is especially important for patients with multiple comorbidities and concomitant medications. Additional monitoring or medication dose adjustments may be needed when switching from one booster to another.

Efficacy and safety of switching from boosted protease inhibitors plus emtricitabine and tenofovir disoproxil fumarate regimens to single-tablet darunavir, cobicistat, emtricitabine, and tenofovir alafenamide at 48 weeks in adults with virologically suppressed HIV-1 (EMERALD): a phase 3, randomised, non-inferiority trial

BACKGROUND

Simplified regimens with reduced pill burden and fewer side-effects are desirable for people living with HIV. We investigated the efficacy and safety of switching to a single-tablet regimen of darunavir, cobicistat, emtricitabine, and tenofovir alafenamide versus continuing a regimen of boosted protease inhibitor, emtricitabine, and tenofovir disoproxil fumarate.

METHODS

EMERALD was a phase-3, randomised, active-controlled, open-label, international, multicentre trial, done at 106 sites across nine countries in North America and Europe. HIV-1-infected adults were eligible to participate if they were treatment-experienced and virologically suppressed (viral load <50 copies per mL for ≥2 months; one viral load of 50-200 copies per mL was allowed within 12 months before screening), and patients with a history of virological failure on non-darunavir regimens were allowed. Randomisation was by computer-generated interactive web-response system and stratified by boosted protease inhibitor use at baseline. Patients were randomly assigned (2:1) to switch to the open-label study regimen or continue the control regimen. The study regimen consisted of a fixed-dose tablet containing darunavir 800 mg, cobicistat 150 mg, emtricitabine 200 mg, and tenofovir alafenamide 10 mg, which was taken once per day for 48 weeks. The primary outcome was the proportion of participants with virological rebound (confirmed viral load ≥50 copies per mL or premature discontinuations, with last viral load ≥50 copies per mL) cumulative through week 48; we tested non-inferiority (4% margin) of the study regimen versus the control regimen in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT02269917.

FINDINGS

The study began on April 1, 2015, and the cutoff date for the week 48 primary analysis was Feb 24, 2017. Of 1141 patients (763 in the study group and 378 in the control group), 664 (58%) had previously received five or more antiretrovirals, including screening antiretrovirals, and 169 (15%) had previous virological failure on a non-darunavir regimen. The study regimen was non-inferior to the control for virological rebound cumulative through week 48 (19 [2·5%] of 763 patients in the study group vs eight (2·1%) of 378 patients in the control group; difference 0·4%, 95% CI -1·5 to 2·2; p<0·0001). No resistance to any study drug was observed. Numbers of discontinuations related to adverse events (11 [1%] of 763 patients in the study group vs four [1%] of 378 patients in the control group) and grade 3-4 adverse events (52 [7%] patients vs 31 [8%] patients) were similar between the two groups. There was a small non-clinically relevant but statistically significant (0·2 [SD 1·1] vs 0·1 [1·1], p=0.010) difference between the two groups in change from baseline in total cholesterol to HDL-cholesterol ratio. Only one serious adverse event (pancreatitis in the study group) was deemed as possibly related to the study regimen.

INTERPRETATION

Our findings show the safety and efficacy of single-tablet darunavir, cobicistat, emtricitabine, and tenofovir alafenamide as a potential switch option for the treatment of HIV-1 infection in adults with viral suppression.

FUNDING

Janssen.

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.

In vitro inhibition of human UGT isoforms by ritonavir and cobicistat

1. Ritonavir and cobicistat are pharmacokinetic boosting agents used to increase systemic exposure to other antiretroviral therapies. The manufacturer's data suggests that cobicistat is a more selective CYP3A4 inhibitor than ritonavir. However, the inhibitory effect of ritonavir and cobicistat on human UDP glucuronosyltransferase (UGT) enzymes in Phase II metabolism is not established. This study evaluated the inhibition of human UGT isoforms by ritonavir versus cobicistat. 2. Acetaminophen and ibuprofen were used as substrates to evaluate the metabolic activity of the principal human UGTs. Metabolite formation rates were determined by HPLC analysis of incubates following in vitro incubation of index substrates with human liver microsomes (HLMs) at different concentrations of ritonavir or cobicistat. Probenecid and estradiol served as positive control inhibitors. 3. The 50% inhibitory concentrations (IC₅₀) of cobicistat and ritonavir were at least 50 µM, which substantially exceeds usual clinical plasma concentrations. Probenecid inhibited the glucuronidation of acetaminophen (IC₅₀ 0.7 mM), but not glucuronidation of ibuprofen. At relatively high concentrations, estradiol inhibited ibuprofen glucuronidation (IC₅₀ 17 µM). 4. Ritonavir and cobicistat are unlikely to produce clinically important drug interactions involving drugs metabolized to glucuronide conjugates by UGT1A1, 1A3, 1A6, 1A9, 2B4 and 2B7.

Significant improvement in triglyceride levels after switching from ritonavir to cobicistat in suppressed HIV-1-infected subjects with dyslipidaemia

OBJECTIVES

Cobicistat seems to have a low rate of adverse events compared with ritonavir.

METHODS

This restrospective observational study to evaluated changes in lipid parameters and the percentage of subjects with dyslipidemia in virologically suppressed HIV-infected patients who were receiving a regimen containing darunavir/ritonavir and were then switched from ritonavir to cobicistat, carried out from December 2015 to May 2016, included 299 HIV-1-infected patients who were on stable antiretroviral treatment including darunavir/ritonavir (monotherapy, bitherapy or triple therapy for at least 6 months) and were then switched from ritonavir to cobicistat. Lipid parameters, as well as plasma HIV-1 RNA and CD4 cell counts, were recorded at baseline just before the switch, and 24 weeks after the switch. Patients were stratified according to the presence of hypercholesterolaemia [baseline total cholesterol > 200 mg/dL and/or low-density lipoprotein (LDL) cholesterol > 130 mg/dL] or hypertriglyceridaemia (baseline triglyceride levels > 200 mg/dL).

RESULTS

Two hundred and ninety-nine patients were enrolled in the study. Fifty-two per cent of the total study population showed dyslipidaemia at baseline. All patients maintained HIV-1 RNA ≤ 50 HIV-1 RNA copies/mL at week 24. No statistically significant changes were seen in CD4 T-cell count from baseline to week 24 [654 (298) to 643 (313) cells/μL; P = 0.173]. When patients were stratified according to the presence of hypercholesterolaemia at baseline (n = 124), significant changes were observed in total cholesterol (P < 0.001), LDL cholesterol (P = 0.047), high-density lipoprotein (HDL) cholesterol (P = 0.002) and triglyceride levels (P = 0.025), and when they were stratified according to the presence of hypertriglyceridaemia at baseline (n = 64), changes from baseline to week 24 in triglyceride level were statistically significant [median (interquartile range) 352 (223, 389) mg/dL at baseline and 229 (131, 279) mg/dL at week 24; P < 0.001].

CONCLUSIONS

Cobicistat as a booster of darunavir in HIV-infected subjects had a beneficial effect on the lipid profile in patients with hypercholesterolaemia or hypertrigliceridaemia at baseline.

Commonly Transmitted HIV-1 Drug Resistance Mutations in Reverse-Transcriptase and Protease in Antiretroviral Treatment-Naive Patients and Response to Regimens Containing Tenofovir Disoproxil Fumarate or Tenofovir Alafenamide

Background

The presence of transmitted drug resistance mutations (TDRMs) in antiretroviral treatment (ART)-naive patients can adversely affect the outcome of ART.

Methods

Resistance testing was conducted in 6704 ART-naive subjects predominantly from the United States and Europe in 9 clinical studies conducted by Gilead Sciences from 2000 to 2013.

Results

The presence of TDRMs increased during this period (from 5.2% to 11.4%), primarily driven by an increase in nonnucleoside reverse-transcriptase (RT) inhibitor (NNRTI) resistance mutations (from 0.3% to 7.1%), particularly K103N/S (increase from 0.3% to 5.3%). Nucleoside/nucleotide RT inhibitor mutations were found in 3.1% of patients. Only 1 patient had K65R (0.01%) and 7 had M184V/I (0.1%), despite high use of tenofovir disoproxil fumarate (TDF), emtricitabine, and lamivudine and potential transmission of resistance to these drugs. At least 1 thymidine-analogue mutations was present in 2.7% of patients with 0.07% harboring T215Y/F and 2.7% harboring T215 revertant mutations (T215rev). Patients with the combination of M41L + L210W + T215rev showed full human immunodeficiency virus RNA suppression while receiving a TDF- or tenofovir alafenamide-containing regimen.

Conclusions

There was an overall increase of TDRMs among patients enrolling in clinical trials from 2000 through 2013, driven primarily by an increase in NNRTI resistance. However, the presence of common TDRMs, including thymidine-analogue mutations/T215rev, showed no impact on response to TDF- or tenofovir alafenamide-containing regimens.

Novel approaches to HIV therapy

There are approximately 35 million people infected by human immunodeficiency virus (HIV), with an estimated 2 million incident infections annually across the globe. While HIV infection was initially associated with high rates of morbidity and mortality, advances in therapy have transformed it into a chronic and manageable disease. In addition, there is very strong evidence that those on antiretroviral therapy are much less likely to transmit infection to their partners. The success rates for maintaining viral suppression in treated patients has dramatically increased owing to the development of agents that are potent and well tolerated and can often be co-formulated into single pills for simplification. This review will outline advances in treatment over the last several years as well as new strategies that may shift the existing treatment paradigm in the near future.

Costs and cost-efficacy analysis of the 2017 GESIDA/Spanish National AIDS Plan recommended guidelines for initial antiretroviral therapy in HIV-infected adults

INTRODUCTION

GESIDA and the Spanish National AIDS Plan panel of experts have recommended preferred (PR), alternative (AR) and other regimens (OR) for antiretroviral therapy (ART) as initial therapy in HIV-infected patients for 2017. The objective of this study was to evaluate the costs and the efficiency of initiating treatment with PR and AR.

METHODS

Economic assessment of costs and efficiency (cost-efficacy) based on decision tree analyses. Efficacy was defined as the probability of reporting a viral load <50copies/mL at week 48, in an intention-to-treat analysis. Cost of initiating treatment with an ART regimen was defined as the costs of ART and its consequences (adverse effects, changes of ART regimen and drug resistance studies) during the first 48 weeks. The payer perspective (National Health System) was applied considering only differential direct costs: ART (official prices), management of adverse effects, resistance studies and HLA B*5701 screening. The setting was Spain and the costs correspond to those of 2017. A deterministic sensitivity analysis was conducted, building three scenarios for each regimen: base case, most favourable and least favourable.

RESULTS

In the base case scenario, the cost of initiating treatment ranged from 6882 euro for TFV/FTC/RPV (AR) to 10,904 euros for TFV/FTC+RAL (PR). The efficacy varied from 0.82 for TFV/FTC+DRV/p (AR) to 0.92 for TAF/FTC/EVG/COBI (PR). The efficiency, in terms of cost-efficacy, ranged from 7923 to 12,765 euros per responder at 48 weeks, for ABC/3TC/DTG (PR) and TFV/FTC+RAL (PR), respectively.

CONCLUSION

Considering ART official prices, the most efficient regimen was ABC/3TC/DTG (PR), followed by TFV/FTC/RPV (AR) and TAF/FTC/EVG/COBI (PR).

Atazanavir sulfate + cobicistat for the treatment of HIV infection

INTRODUCTION

During last two decades several drugs were developed to offer long-term benefits in terms of virologic efficacy, favourable tolerability and toxicity profiles in treatment of HIV infection. Pharmacokinetics boosting of protease inhibitor allows a higher genetic barrier, as few or no drug-resistant mutations are detected in patients with virologic failure. Areas covered: Atazanavir sulfate + cobicistat (ATV/c) was recently approved for the treatment of HIV-1 infection. Bioequivalence between cobicistat (COBI) and ritonavir (RTV) as a pharmacoenhancer of ATV was established. Additionally, randomized clinical trials demonstrated that ATV/c and ATV/ritonavir had comparable efficacy and safety profiles. Low rates of virologic failure and no ATV resistance mutations were observed in these clinical trials. Therefore, COBI shows increased advantages over RTV, such as no activity against HIV, fewer drug-drug interactions and better solubility, which promotes coformulation strategies with less pill burden, better tolerability, and, potentially, higher life-long treatment adherence. Expert commentary: ATV/c regimen supports its useas an effective treatment option for HIV-1 infected patients with increased cardiovascular disease and chronic kidney disease risk associated with aging. In addition, ATV/c is a new opportunity to expand the strategy of switch to a dual therapy to lower the risk of long-term toxicities as well as the advantage of its cost-benefit.

Treatment-limiting renal tubulopathy in patients treated with tenofovir disoproxil fumarate

OBJECTIVES

Tenofovir disoproxil fumarate (TDF) is widely used in the treatment or prevention of HIV and hepatitis B infection. TDF may cause renal tubulopathy in a small proportion of recipients. We aimed to study the risk factors for developing severe renal tubulopathy.

METHODS

We conducted an observational cohort study with retrospective identification of cases of treatment-limiting tubulopathy during TDF exposure. We used multivariate Poisson regression analysis to identify risk factors for tubulopathy, and mixed effects models to analyse adjusted estimated glomerular filtration rate (eGFR) slopes.

RESULTS

Between October 2002 and June 2013, 60 (0.4%) of 15,983 patients who had received TDF developed tubulopathy after a median exposure of 44.1 (IQR 20.4, 64.4) months. Tubulopathy cases were predominantly male (92%), of white ethnicity (93%), and exposed to antiretroviral regimens that contained boosted protease inhibitors (PI, 90%). In multivariate analysis, age, ethnicity, CD4 cell count and use of didanosine or PI were significantly associated with tubulopathy. Tubulopathy cases experienced significantly greater eGFR decline while receiving TDF than the comparator group (-6.60 [-7.70, -5.50] vs. -0.34 [-0.43, -0.26] mL/min/1.73 m²/year, p < 0.0001).

CONCLUSIONS

Older age, white ethnicity, immunodeficiency and co-administration of ddI and PI were risk factors for tubulopathy in patients who received TDF-containing antiretroviral therapy. The presence of rapid eGFR decline identified TDF recipients at increased risk of tubulopathy.

Modifying Antiretroviral Therapy in Virologically Suppressed HIV-1-Infected Patients

HIV-1-infected patients with suppressed plasma viral loads often require changes to their antiretroviral (ARV) therapy to manage drug toxicity and intolerance, to improve adherence, and to avoid drug interactions. In patients who have never experienced virologic failure while receiving ARV therapy and who have no evidence of drug resistance, switching to any of the acceptable US Department of Health and Human Services first-line therapies is expected to maintain virologic suppression. However, in virologically suppressed patients with a history of virologic failure or drug resistance, it can be more challenging to change therapy while still maintaining virologic suppression. In these patients, it may be difficult to know whether the discontinuation of one of the ARVs in a suppressive regimen constitutes the removal of a key regimen component that will not be adequately supplanted by one or more substituted ARVs. In this article, we review many of the clinical scenarios requiring ARV therapy modification in patients with stable virologic suppression and outline the strategies for modifying therapy while maintaining long-term virologic suppression.

Evolution of renal function in African patients initiating second-line antiretroviral treatment: findings from the ANRS 12169 2LADY trial

BACKGROUND

To investigate change in renal function in African patients initiating second-line antiretroviral therapy (ART) including ritonavir-boosted protease inhibitor (PI/r) with or without tenofovir disoproxil fumarate (TDF).

METHODS

HIV-1-positive adults, failing standard first-line ART were randomized to either TDF/emtricitabine (FTC)+LPV/r, abacavir + didanosine +LPV/r or TDF/FTC+ darunavir (DRV)/r and followed for 18 months. Patients with an estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m² at baseline were included in this analysis.

RESULTS

Data from 438 out of 454 randomized patients were analysed. Median age was 38 years and 72% were women. Initiation of PI/r-based second-line regimen induced a marked eGFR decline of -10.5 ml/min/1.73 m² at week 4 in all treatment groups with a greater decrease in TDF/FTC+LPV/r arm (-15.1 ml/min/1.73 m²). At month 18, mean eGFR in the non-TDF containing regimen recovered its baseline level and was significantly greater than eGFR 18-month levels in the TDF-containing regimens that experienced only partial recovery (difference: -10.7; CI -16.8, -4.6; P=0.001 in TDF/FTC+LPV/r and -6.4; CI -12.5, -0.3; P=0.04 in TDF/FTC+DRV/r). At 18 months, prevalence of stage 3 chronic kidney disease was low (<3%) and not associated with treatment. One treatment discontinuation and five TDF dosage reductions for renal toxicities were reported in TDF-containing arms.

CONCLUSIONS

Overall, these results suggest a reasonable renal tolerance of a regimen associating TDF/FTC+PI/r in African patients with eGFR>60 ml/ml/1.73 m² at baseline. They also support the recommendation of reassessing renal function 1 month after initiation of treatment including ritonavir to account for the ritonavir-related artefactual decrease of eGFR and determine the new reference baseline value.

Therapeutic drug monitoring of antiretroviral drugs in HIV-infected patients

INTRODUCTION

Therapeutic drug monitoring (TDM) may be beneficial when applied to antiretroviral (ARV). Even though TDM can be a valuable strategy in HIV management, its role remains controversial. Areas covered: This review provides a comprehensive update on important issues relating to TDM of ARV drugs in HIV-infected patients. Articles from PubMed with keywords relevant to each topic section were reviewed. Search strategies limited to articles published in English. Expert commentary: There is evidence supporting the use of TDM in HIV treatment. However, some limitations need to be considered. The evidence supporting the use of routine TDM for all patients is limited, as it is not clear that this strategy offers any advantages over TDM for selected indications. Selected groups of patients including patients with physiological changes, patients with drug-drug interactions or toxicity, and the elderly could potentially benefit from TDM, as optimized dosing is challenging in these populations.

Co-administration of elvitegravir/cobicistat/tenofovir disoproxil fumarate/emtricitabine and atazanavir in treatment-experienced HIV patients

We report the use of elvitegravir 150 mg/cobicistat 150 mg/tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg (EVG/COBI/TDF/FTC) once daily, in addition to once-daily atazanavir (ATV) 300 mg, in treatment-experienced patients with human immunodeficiency virus (HIV). Due to limited data available on the co-administration of these agents, our objective was to evaluate and monitor safety and efficacy of this regimen in patients who developed resistance or intolerance to conventional antiretroviral therapy (ART). This short report included offenders incarcerated in the Illinois Department of Corrections who were ≥18 years, HIV-infected, had documented antiretroviral resistance, and received EVG/COBI/TDF/FTC + ATV once daily. Based on previous ART, resistance patterns and current medications, seven patients were initiated on once-daily therapy consisting of EVG/COBI/TDF/FTC and ATV. Due to extensive resistance, two of the seven patients were also started on abacavir (ABC) 600 mg daily in addition to EVG/COBI/TDF/FTC and ATV. Of the seven patients, one had ART changed due to concerns of resistance based on a genotype, one experienced a decline in renal function that warranted a change in therapy, and one is currently virologically suppressed on a combination of EVG/COBI/TDF/FTC, ATV, and ABC. The remaining four patients remain virologically suppressed on EVG/COBI/TDF/FTC + ATV. Therapy consisting of EVG/COBI/TDF/FTC and ATV may be a viable option for some treatment-experienced HIV-infected patients. Further studies evaluating the safety, efficacy, and pharmacokinetics of this therapy are warranted, given the lack of information currently available.

New Antiretroviral Treatment for HIV

The Joint United Nations Programme on HIV/AIDS (UNAIDS) has set the global goal of ending the AIDS world epidemic by 2030. In order to end this epidemic they have established a 90-90-90 goal to be achieved by 2020, which may be problematic, especially in low- and middle-income countries. This goal includes 90% of individuals with HIV globally being diagnosed, on treatment, and virologically suppressed. Based on global estimates from 2014-2015, approximately 36.9 million individuals are living with HIV. Of those, 53% have been diagnosed with HIV, 41% are on antiretroviral therapy (ART), and 32% have viral suppression with <1000 copies/ml. Comprehensive approaches are needed to improve the number of people living with HIV (PLWH) who are diagnosed, linked, and engaged in care. Once PLWH are retained in care, treatment is key to both HIV prevention and transmission. The development and advancement of new ART is necessary to assist in reaching these goals by improving safety profiles, decreasing pill burden, improving quality of life and life expectancy, and creating new mechanisms to overcome resistance. The focus of this review is to highlight and review data for antiretroviral agents recently added to the market as well as discuss agents in various stages of development (new formulations and mechanisms of action).

Risk of Cardiovascular Disease in an Aging HIV Population: Where Are We Now?

With more effective and widespread antiretroviral treatment, the overall incidence of AIDS- or HIV-related death has decreased dramatically. Consequently, as patients are aging, cardiovascular disease (CVD) has emerged as an important cause of morbidity and mortality in the HIV population. The incidence of CVD overall in HIV is relatively low, but it is approximately 1.5-2-fold higher than that seen in age-matched HIV-uninfected individuals. Multiple factors are believed to explain this excess in risk such as overrepresentation of traditional cardiovascular risk factors (particularly smoking), toxicities associated with cumulative exposure to some antiretroviral agents, together with persistent chronic inflammation, and immune activation associated with HIV infection. Tools are available to calculate an individual's predicted risk of CVD and should be incorporated in the regular follow-up of HIV-infected patients. Targeted interventions to reduce this risk must be recommended, including life-style changes and medical interventions that might include changes in antiretroviral therapy.

Costs and cost-efficacy analysis of the 2016 GESIDA/Spanish AIDS National Plan recommended guidelines for initial antiretroviral therapy in HIV-infected adults

INTRODUCTION

GESIDA and the AIDS National Plan panel of experts suggest preferred (PR), alternative (AR), and other regimens (OR) for antiretroviral treatment (ART) as initial therapy in HIV-infected patients for the year 2016. The objective of this study is to evaluate the costs and the efficacy of initiating treatment with these regimens.

METHODS

Economic assessment of costs and efficiency (cost/efficacy) based on decision tree analyses. Efficacy was defined as the probability of reporting a viral load <50copies/mL at week 48 in an intention-to-treat analysis. Cost of initiating treatment with an ART regimen was defined as the costs of ART and its consequences (adverse effects, changes of ART regimen, and drug resistance studies) during the first 48 weeks. The payer perspective (National Health System) was applied, only taking into account differential direct costs: ART (official prices), management of adverse effects, studies of resistance, and HLA B*5701 testing. The setting is Spain and the costs correspond to those of 2016. A sensitivity deterministic analysis was conducted, building three scenarios for each regimen: base case, most favourable, and least favourable.

RESULTS

In the base case scenario, the cost of initiating treatment ranges from 4663 Euros for 3TC+LPV/r (OR) to 10,894 Euros for TDF/FTC+RAL (PR). The efficacy varies from 0.66 for ABC/3TC+ATV/r (AR) and ABC/3TC+LPV/r (OR), to 0.89 for TDF/FTC+DTG (PR) and TDF/FTC/EVG/COBI (AR). The efficiency, in terms of cost/efficacy, ranges from 5280 to 12,836 Euros per responder at 48 weeks, for 3TC+LPV/r (OR), and RAL+DRV/r (OR), respectively.

CONCLUSION

Despite the overall most efficient regimen being 3TC+LPV/r (OR), among the PR and AR, the most efficient regimen was ABC/3TC/DTG (PR). Among the AR regimes, the most efficient was TDF/FTC/RPV.

Evaluation of pharmacokinetic interactions between long-acting HIV-1 fusion inhibitor albuvirtide and lopinavir/ritonavir, in HIV-infected subjects, combined with clinical study and simulation results

1. A clinical study to assess the interactions between albuvirtide (320 mg) and lopinavir/ritonavir (400/100 mg) was conducted in 10 HIV-1-infected subjects. Because albuvirtide requires a long period to achieve steady state, and extended monotherapy may lead to early resistance, it is unethical to take albuvirtide alone to achieve steady state. Therefore, a population pharmacokinetic model was developed to predict steady-state concentration-time curve of solely administered albuvirtide. 2. When albuvirtide and lopinavir/ritonavir were co-administered, the plasma concentration of albuvirtide when the infusion ended (C_end) increased by about 34%, but the geometric mean ratios and 90% confidence intervals (90% CIs) of AUC_(0-t) [1.09 (0.96-1.24)] and C_trough [1.00 (0.83-1.20)] were within the range of 0.8-1.25. For lopinavir, the ratios (90% CIs) of AUC_(0-t), C_max and C_trough were 0.63 (0.49-0.82), 0.67 (0.53-0.86) and 0.65 (0.46-0.91); for ritonavir, those ratios (90% CIs) were 0.62 (0.42-0.91), 0.61 (0.38-0.99) and 0.72 (0.40-1.26), respectively. 3. Co-administration of albuvirtide with lopinavir/ritonavir has little effect on albuvirtide exposure, but it decreases the plasma exposures of lopinavir/ritonavir. However, the drug-drug interactions may not reduce the effectiveness of this co-therapy, the trough concentration of lopinavir may be sufficient and this combination could achieve similar clinical efficacy with marketed drugs. So, a phase 3 clinical trial without dose adjustment is underway to validate their effectiveness and safety.

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for UGT1A1 and Atazanavir Prescribing

The antiretroviral protease inhibitor atazanavir inhibits hepatic uridine diphosphate glucuronosyltransferase (UGT) 1A1, thereby preventing the glucuronidation and elimination of bilirubin. Resultant indirect hyperbilirubinemia with jaundice can cause premature discontinuation of atazanavir. Risk for bilirubin-related discontinuation is highest among individuals who carry two UGT1A1 decreased function alleles (UGT1A1*28 or *37). We summarize published literature that supports this association and provide recommendations for atazanavir prescribing when UGT1A1 genotype is known (updates at www.pharmgkb.org).

Evaluating the role of atazanavir/cobicistat and darunavir/cobicistat fixed-dose combinations for the treatment of HIV-1 infection

Atazanavir/cobicistat (ATV/c) and darunavir/cobicistat (DRV/c) are newly approved once daily fixed-dose protease inhibitor combinations for the treatment of HIV-1 infection. Studies in healthy volunteers have established bioequivalence between cobicistat and ritonavir as pharmacoenhancers of both atazanavir (ATV) and darunavir (DRV). In addition, two randomized clinical trials (one Phase II and one Phase III noninferiority trial with a 144-week followup period) demonstrated that cobicistat had sustainable and comparable efficacy and safety to ritonavir as a pharmacoenhancer of ATV through 144 weeks of treatment in HIV-1-infected patients. Furthermore, one Phase III, open-label, single-arm, clinical trial reflected virologic and immunologic responses and safety outcomes consistent with prior published data for DRV/ritonavir 800/100 mg once daily, supporting the use of DRV/c 800/150 mg once daily for future treatment of treatment-naïve and -experienced HIV-1-infected patients with no DRV resistance-associated mutations. Low rates of virologic failure secondary to resistance to antiretroviral regimens were present in these clinical studies. Most notable adverse events in the ATV studies were hyperbilirubinemia and in the DRV study rash. Small increases in serum creatinine and minimally reduced estimated glomerular filtration rate Cockcroft-Gault calculation (eGFRCG) were observed in ATV/c and DRV/c clinical studies consistent with other studies evaluating elvitegravir/cobicistat/tenofovir/emtricitabine for the treatment of HIV-1 infection. These renal parameter changes occurred acutely in the first few weeks and plateaued off for the remaining study periods and are not necessarily clinically relevant. Cobicistat has numerous advantages compared to ritonavir such as fewer drug-drug interactions, being devoid of anti-HIV-1 activity, as well as it has better solubility affording coformulation with other antiretrovirals as simplified fixed-dose combinations. Overall, the recent approval of ATV/c and DRV/c offers HIV patients opportunities for improved adherence to lifelong treatment. Future studies are warranted to determine the efficacy and safety of ATV/c and DRV/c in treatment-experienced patients.

Darunavir/cobicistat once daily for the treatment of HIV

A current focus in HIV management is improving adherence by minimizing pill burden with convenient formulations, including fixed-dose combinations (FDCs). Darunavir, a HIV protease inhibitor, co-administered with low-dose ritonavir (800/100 mg once daily), is recommended in guidelines in combination with other antiretrovirals for HIV patients with no darunavir resistance-associated mutations. Cobicistat is an alternative agent to ritonavir for boosting plasma drug levels of darunavir among other antiretrovirals. Cobicistat is a more specific cytochrome P450 3A inhibitor than ritonavir without enzyme-inducing properties. This review describes the differing effects of cobicistat and ritonavir on metabolic enzymes, which explains their differing drug-drug interactions, and summarizes some of the studied drug-drug interactions for cobicistat. It also outlines the clinical development and data for a once-daily darunavir/cobicistat FDC. This FDC thus allows for a once-daily treatment regimen (including background antiretrovirals) with reduced pill burden.

Choice of antiretroviral drugs for continued treatment scale-up in a public health approach: what more do we need to know?

INTRODUCTION

There have been several important developments in antiretroviral treatment in the past two years. Randomized clinical trials have been conducted to evaluate a lower dose of efavirenz (400 mg once daily). Integrase inhibitors such as dolutegravir have been approved for first-line treatment. A new formulation of tenofovir (alafenamide) has been developed and has shown equivalent efficacy to tenofovir in randomized trials. Two-drug combination treatments have been evaluated in treatment-naïve and -experienced patients. The novel pharmacokinetic booster cobicistat has been compared to ritonavir in terms of pharmacokinetics, efficacy and safety. The objective of this commentary is to assess recent developments in antiretroviral drug treatment to determine whether new treatments should be included in new international guidelines.

DISCUSSION

The use of first-line treatment with tenofovir and efavirenz at the standard 600 mg once-daily dose should remain the first-choice standard of care treatment. Evidence supporting a switch to efavirenz 400 mg once daily or integrase inhibitors is sufficient to consider these drugs as alternative first-line options, but more data are needed on their use in pregnant women and people with TB co-infection. The use of new formulations of tenofovir is currently too preliminary to justify immediate adoption and scale-up across HIV programmes in low- and middle-income countries. The evidence supporting use of two-drug combinations is not considered strong enough to justify changed recommendations from use of standard triple drug combinations. Cobicistat does not offer significant safety advantages over ritonavir as a pharmacokinetic booster.

CONCLUSIONS

For continued scale-up of antiretroviral treatment in low- and middle-income countries, use of first-line triple combinations including efavirenz 600 mg once daily is supported by the largest evidence base. Additional studies are underway to evaluate new treatments in key populations, and these results may justify changes to these recommendations.

Updates on the Pharmacologic Treatment of Individuals with Human Immunodeficiency Virus

Human immunodeficiency virus has been affecting the human population for more than 30 years. During this time period, more effective, safe, simple, and tolerable pharmacologic agents have been developed. To date, there are 26 antiretroviral agents available that are used either as a single agent or a coformulation in an antiretroviral regimen. The goal of these medications is to achieve viral suppression in individuals infected with human immunodeficiency virus. Evidence continues to support the most effective combinations. It is important that clinicians are knowledgeable of updates so as to provide the best possible medical regimen for this population.

Clinical use of cobicistat as a pharmacoenhancer of human immunodeficiency virus therapy

The pharmacoenhancement of plasma concentrations of protease inhibitors by coadministration of so-called boosters has been an integral part of antiretroviral therapy for human immunodeficiency virus (HIV) for 1.5 decades. Nearly all HIV protease inhibitors are combined with low-dose ritonavir or cobicistat, which are able to effectively inhibit the cytochrome-mediated metabolism of HIV protease inhibitors in the liver and thus enhance the plasma concentration and prolong the dosing interval of the antiretrovirally active combination partners. Therapies created in this way are clinically effective regimens, being convenient for patients and showing a high genetic barrier to viral resistance. In addition to ritonavir, which has been in use since 1996, cobicistat, a new pharmacoenhancer, has been approved and is widely used now. The outstanding property of cobicistat is its cytochrome P450 3A-selective inhibition of hepatic metabolism of antiretroviral drugs, in contrast with ritonavir, which not only inhibits but also induces a number of cytochrome P450 enzymes, UDP-glucuronosyltransferase, P-glycoprotein, and other cellular transporters. This article reviews the current literature, and compares the pharmacokinetics, pharmacodynamics, and safety of both pharmacoenhancers and discusses the clinical utility of cobicistat in up-to-date and future HIV therapy.