A Randomized, Double-Blind, Placebo-Controlled, Short-Term Monotherapy Study of MK-6186, an HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor, in Treatment-Naïve HIV-Infected Participants

Objective: To assess the antiviral activity, pharmacokinetics, and safety of MK-6186 in HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI)-naïve, HIV-1-infected male participants. Design: Double-blind, randomized, two-panel study. Methods: In 2 sequential panels, 18 participants received MK-6186 (40 mg [Panel A] or 150 mg [Panel B]) or matching placebo once daily for 7 days. Plasma samples were collected for measurement of HIV-1 RNA levels and MK-6186 pharmacokinetics. Results: For the mean change from baseline in HIV-1 RNA (log10 copies/mL) at 24 h post Day 7 dose, the mean difference (90% confidence interval) between MK-6186 and placebo was -1.54 (-1.73, -1.34) in the 40-mg group and -1.28 (-1.81, -0.75) in the 150-mg group. One participant in the 150-mg group had viral rebound at 24 h after Day 6 dosing (Day 7 predose) associated with outgrowth of the V106A minority variant. Ultra-deep sequencing confirmed expansion of this predose minority variant from 0.26% to 63.67%. No outgrowth or rebound was seen in another participant in whom a V106A minority variant was also detected. MK-6186 was generally well tolerated. MK-6186 was rapidly absorbed with peak concentrations at 2 h followed by a biphasic decline. The effective t½ of MK-6186 was 43.9 to 48.7 h. Steady state was not achieved. Conclusions: Daily monotherapy with MK-6186 demonstrated robust antiviral activity with maximal antiviral activity at a dose of 40 mg. One participant in the 150-mg group exhibited viral rebound with outgrowth of the resistant V106A minority variant, demonstrating a risk of resistance development typical of NNRTIs. The reason for this outgrowth remains unclear as no outgrowth occurred in a participant in the 40-mg group in whom the V106A minority variant was also detected. MK-6186 may be an alternative next-generation NNRTI in combination therapy, in that combination antiretroviral therapy could prevent outgrowth of resistant minority variants.

Real world utilisation of doravirine among people living with human immunodeficiency virus in England (DRIVE-REAL)

BACKGROUND

Doravirine is a non-nucleoside reverse transcriptase inhibitor recommended for the treatment of virologically suppressed and treatment naïve people living with HIV. The DRIVE-REAL study aimed to describe the characteristics, treatment patterns, and virological outcomes of doravirine users in a real-world cohort in the UK.

METHODS

A retrospective, observational, multi-centre chart review was conducted for 300 adults living with HIV initiating doravirine-containing antiretroviral therapy.

RESULTS

At baseline 83% of individuals were male, 45% aged ≥50 years, 65% white ethnicity. Median time since HIV diagnosis was 12 years. 96% were antiretroviral therapy-experienced, 87% had a HIV viral load <50 copies/ml, and 15% had resistance to at least one antiretroviral drug. 66% had comorbidities, most commonly depression (26%), and 70% were taking at least one co-medication. At six months, 94% (n = 283/300) were still receiving doravirine. Viral load data were available for n = 266/300 individuals and 95% (n = 253/266) had viral load <50 copies/ml.

CONCLUSIONS

Individuals initiating doravirine in this cohort are predominantly treatment-experienced white middle-aged males, with a high frequency of comorbidities and co-medication. The majority of individuals at 6 months remained on doravirine and maintained or achieved HIV viral suppression. This study provides epidemiologic characteristics that can inform clinical care and subsequent hypothesis-testing studies.

Consideration of Nevirapine Analogs To Reduce Metabolically Linked Hepatotoxicity: A Cautionary Tale of the Deuteration Approach

Idiosyncratic drug reactions (IDRs) in their most deleterious form can lead to serious medical complications and potentially fatal events. Nevirapine (NVP), still widely used in developing countries for combinatorial antiretroviral and prophylactic therapies against HIV infection, represents a prototypical example of IDRs causing severe skin rashes and hepatotoxicity. Complex metabolic pathways accompanied by production of multiple reactive metabolites often complicate our understanding of IDR's origin. While assessment of NVP analogs has helped characterize the pathways involved in IDRs for NVP, which are largely driven by metabolism at the 12-methyl position, it has yet to be investigated if some of these analogs could be valuable replacement drugs with reduced reactive metabolite properties and drug-drug interaction (DDI) risks. Here, we evaluated a set of eight NVP analogs, including the deuterated 12-d3-NVP and two NVP metabolites, for their efficacy and inhibitory potencies against HIV reverse transcriptase (HIV-RT). A subset of three analogs, demonstrating >85% inhibition for HIV-RT, was further assessed for their hepatic CYP induction-driven DDI risks. This led to a closer investigation of the inactivation properties of 12-d3-NVP for hepatic CYP3A4 and a comparison of its propensity in generating reactive metabolite species. The metabolic shift triggered with 12-d3-NVP, increasing formation of the 2-hydroxy and glutathione metabolites, emphasized the importance of the dynamic balance between induction and metabolism-dependent inactivation of CYP3A4 and its impact on clearance of NVP during treatment. Unfortunately, the strategy of incorporating deuterium to reduce NVP metabolism and production of the electrophile species elicited opposite results, illustrating the great challenges involved in tackling IDRs through deuteration.

Early versus delayed antiretroviral therapy based on genotypic resistance test: Results from a large retrospective cohort study

Rapid start of antiretroviral therapy (ART) pending genotypic resistance test (GRT) has been recently proposed, but the effectiveness of this strategy is still debated. The rate of virological success (VS), defined as HIV‐RNA < 50 copies/ml, with and without GRT was compared in drug‐naïve individuals enrolled in the Italian ARCA cohort who started ART between 2015 and 2018. 521 individuals started ART: 397 without GRT (pre‐GRT group) and 124 following GRT (post‐GRT group). Overall, 398 (76%) were males and 30 (6%) were diagnosed with AIDS. In the pre‐GRT group, baseline CD4+ cell counts were lower (p < 0.001), and viral load was higher (p < 0.001) than in the post‐GRT group. The estimated probability of VS in pre‐GRT versus post‐GRT group was 72.54% (CI₉₅: 67.78–76.60) versus 66.94% (CI₉₅: 57.53–74.26) at Week 24 and 92.40% (CI₉₅: 89.26–94.62) versus 92.92% (CI₉₅: 86.35–96.33) at Week 48, respectively (p = 0.434). At Week 48, VS was less frequent among individuals with baseline CD4+ cell counts <200 versus >500 (90.33% vs. 97.33%), log viral load <5.00 versus >5.70 log₁₀ cps/ml (97.17% vs 78.16%; p < 0.001), and those treated with protease inhibitors or non‐nucleoside reverse transcriptase inhibitors versus those treated with integrase strand transfer inhibitors (p < 0.001). The rate of VS does not seem to be affected by an early ART initiation pending GRT results, but it could be influenced by the composition of the ART regimen, as well as immuno‐virological parameters.

Predictors of Poor Adherence to CART and Treatment Failure at Second-Line Regimens Among Adults in Public Hospitals of Amhara Region, North-Western Ethiopia: A Retrospective Cohort Study

BACKGROUND

Globally, HIV/AIDS has challenged the lives of 36.3 million people and resulted in 17 million orphans. The disease has neither a vaccine nor a cure and the only option currently is highly active antiretroviral therapy. This research was conducted to identify the predictors of poor adherence to CART and treatment failure at second-line regimen among adults living with HIV/AIDS in public hospitals of Amhara region, north-western Ethiopia.

METHODS

A retrospective cohort study design was conducted on 700 HIV-positive people who were receiving a second-line CART regimen. Participants on second-line regimens who followed their treatment between 2016 and 2019 were considered. Data were extracted from participants' clinical charts from June 18-July 7, 2020.

RESULTS

A multivariate regression analysis indicates that age of patients (OR = 1.025, 95% CI: 1.001-1.321; p = 0.005), follow-up visits (OR = 0.979, 95% CI: 0.873-0.998; p < 0.001), CD4 cell count change (OR = 0.9860; 95% CI: 0.835-0.998; p < 0.01), marital status (OR = 0.973, 95% CI: 0.789- 0.997; p = 0.006), female HIV-infected patients (OR = 0.990; 95% CI: 0.789-0.999; p <0.001), rural patients (OR = 1.151; 95% CI 1.065-1.398; p = 0.004), non-educated adult patients (OR = 1.026, 95% CI: 1.002-1.198; p = 0.003), existence of social violence (OR = 0.012, 95% CI: 0.008-0.134; p< 0.01), patients with opportunistic diseases (OR = 1.0345, 95% CI 1.002-1.142; p = 0.001), CD4 cell count (OR = 0.901, 95% CI: 0.843-0.995; p = 0.025) and malnutrition (OR = 0.883, 95% CI; 0.762-0.954; p = 0.001) significantly affected the two response variables.

CONCLUSION

Several variables affected both poor adherence to HAART and treatment failure at second-line regimens in the current investigation. Due attention should be given to aged patients, rural residents, non-educated patients, and patients with other morbidities to be successful with second-line treatment regimens.

Modeling HIV Pre-Exposure Prophylaxis

Pre-exposure prophylaxis (PrEP) has emerged as a promising strategy for preventing the transmission of HIV. Although only one formulation is currently approved for PrEP, research into both new compounds and new delivery systems for PrEP regimens offer intriguing challenges from the perspective of pharmacokinetic and pharmacodynamic modeling. This review aims to provide an overview the current modeling landscape for HIV PrEP, focused on PK/PD and QSP models relating to antiretroviral agents. Both current PrEP treatments and new compounds that show promise as PrEP agents are highlighted, as well as models of uncommon administration routes, predictions based on models of mechanism of action and viral dynamics, and issues related to adherence to therapy. The spread of human immunodeficiency virus (HIV) remains one of the foremost global health concerns. In the absence of a vaccine, other prophylactic strategies have been developed to prevent HIV transmission. One approach, known as pre-exposure prophylaxis (PrEP), allows HIV-negative individuals who are at high risk of exposure to the virus, be it through an HIV-positive sexual partner or through the shared use of drug injection equipment, to substantially reduce the risk of developing an HIV infection. PrEP is a relatively recent approach to combating the HIV epidemic, with the only currently approved treatment being Truvada, a daily oral antiretroviral (ARV) therapy initially indicated in the treatment of active HIV-1 infections, but approved for HIV PrEP in 2012. Although PrEP therapy has consistently demonstrated high efficacy in preventing HIV infection, this efficacy is dependent on patient adherence to the prescribed treatment regimen. This can present a significant problem in low- and middle-income countries, which may lack the infrastructure to provide sufficient access to PrEP medication to maintain daily dosing regimens. Furthermore, while the conventional approach has generally been to advocate for continuous administration akin to regimens used for viral suppression in infected patients, there has been some discussion of whether a better treatment paradigm might be to push for PrEP therapy primarily during those known periods of heightened exposure risk, while relying on post-exposure prophylaxis regimens to prevent infection after unanticipated exposures during low-risk periods. These considerations have led to a push for the development of long-duration and on-demand PrEP formulations, including subdermal and subcutaneous implants, slow-release intramuscular depot injections, vaginal and rectal antimicrobial gels, and intravaginal rings and dissolving films. PrEP therapy is a quickly evolving field, with a variety of antiretroviral compounds and formulations under investigation. This review aims to report on notable drugs and formulations from a pharmacokinetic/pharmacodynamic (PK/PD) modeling perspective. Given the nature of PrEP as a preventive therapy designed for long-term use, clinical trials for PrEP therapies can last for months or even years, particularly in the case of long-duration formulations. Furthermore, in contrast to antiretroviral trials in infected patients, pharmacodynamic endpoints in PrEP therapies are difficult to quantify, as the primary endpoint for efficacy is generally the rate of seroconversion. Computational modeling approaches offer flexible and powerful tools to provide insight into drug behavior in clinical settings, and can ultimately reduce the time, expense, and patient burden incurred in the development of PrEP therapies.

Rational Design of Doravirine: From Bench to Patients

Since the approval of nevirapine, the first HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI) in 1996, NNRTIs have helped play a critical role in maintaining viral suppression in people living with HIV. The many positive attributes of the class, including potency and long plasma half-life, make them attractive drug discovery targets. Given the availability of multiple once-daily integrase-based treatments for HIV-1 infection, the challenge to develop a new antiretroviral agent that addresses the needs of today's patients is formidable. However, with the increased availability of antiretrovirals for treatment and new pre-exposure prophylaxis guidelines, which should globally expand the use of antiretrovirals in prevention, it will be increasingly important to have access to multiple regimens with options from different classes that are well tolerated and convenient to ensure a sustained impact on the global epidemic. Many attempts to improve upon the NNRTI class have failed to deliver a desirable clinical profile consistent with the current landscape of treatment options. Doravirine is the only NNRTI to successfully advance through phase 3 clinical development and approval in recent years. Learning from the liabilities of approved NNRTIs, as well as past development failures, facilitated a rational approach to the discovery of doravirine by focusing on addressing the known safety/tolerability issues of commonly prescribed NNRTIs, such as central nervous system toxicity with efavirenz and potential cardiotoxicity due to off-target effects on cardiac ion channels with rilpivirine, using structural biology and characterization of resistance in vitro to address resistance liabilities and concentrating on the metabolic profile to limit the potential for drug-drug interactions. These preclinical efforts were critical to the design and selection of doravirine as a novel NNRTI that possessed the desired next-generation profile with the ultimate proof that these attributes translate to patients derived from clinical trials.

The Influence of Antiretroviral Therapy on Hepatitis C Virus Viral Load and Liver Fibrosis in Human Immunodeficiency Virus-Coinfected Patients: An Observational Study

BACKGROUND

The role of antiretroviral therapy (ART) for Hepatitis C viral load (HCV-VL) and liver fibrosis is poorly understood. This study aimed at evaluating the influence of ART on HCV-VL and liver fibrosis in human immunodeficiency virus (HIV)/HCV-coinfected patients.

METHODS

We conducted a retrospective cohort study of HIV/HCV-coinfected patients followed at a tertiary university hospital.

RESULTS

In total, 143 patients were included. In 61 patients, ART initiation was accompanied by an increase in HCV-VL and a decrease in HIV viral load (HIV-VL), whereas ART suspension led to a decrease in HCV-VL and an increase in HIV-VL. Among the 55 HIV-suppressed patients who switched to a raltegravir (RAL)-containing regimen, median HCV-VL levels decreased significantly, while switching to a rilpivirine-containing regimen did not yield a significant reduction.

DISCUSSION

If the -treatment of chronic hepatitis starts before ART, ART initiation should be delayed as much as possible. If ART has been started, it is advisable to wait 1 year before initiating chronic hepatitis treatment. RAL as the third agent in an ART regimen could be beneficial in HIV/HCV-coinfected patients, in comparison to other antiretroviral drugs.

CONCLUSION

The start and the suspension of ART significantly interferes with HCV-VL in HIV/HCV-coinfected patients.

A Multiple Dose Phase 1 Assessment of Rilpivirine Long Acting in a Model of Preexposure Prophylaxis Against HIV

The MWRI-01 study characterized the safety, acceptability, pharmacokinetic (PK), and pharmacodynamic (PD) profile of rilpivirine (RPV) long acting (LA) in a model of preexposure prophylaxis (PrEP). Prospective, open-label Phase 1 study. The safety and acceptability of three repeated doses of RPV LA were monitored. Blood, tissue (rectal, cervical, and vaginal), and biological fluids (vaginal and endocervical) were collected at baseline and at 1- to 2-month intervals throughout the study for PK and PD assessment. Eight women and four men received three intramuscular doses of 1,200 mg of RPV LA given 8 weeks apart. There were a total of 195 adverse events (AEs) reported, of which 138 (70.8%) were Grade 1 and 55 (28.2%) were Grade 2. The most common AE was injection site pain. Geometric mean (90% confidence interval) plasma RPV concentrations at 56 days after the first and third doses were 39 (33-45) ng/mL (female)/29 (17-40) ng/mL (male) and 59 (45-62) ng/mL (female)/40 (30-51) ng/mL (male), respectively. Exposure to RPV LA was associated with significant inhibition of HIV-1_BaL viral replication in the ex vivo rectal explant model (p < .0001) that persisted for up to 4 months after the third dose of RPV LA. In contrast, no viral suppression was seen in cervicovaginal tissue. Multiple dose administration of RPV LA was safe and well tolerated, and was associated with prolonged suppression of viral replication in rectal explant tissue.

Rilpivirine long-acting for the prevention and treatment of HIV infection

PURPOSE OF REVIEW

Rilpivirine is a non-nucleoside reverse transcriptase inhibitor approved for the treatment of HIV in combination with other antiretrovirals (ARV). The development of the long-acting formulation of rilpivirine (RPV-LA) and its use in clinical settings is the subject of this review.

RECENT FINDINGS

In 2017, the results of the phase IIb study LATTE2 have been published. This study demonstrated that the combination of RPV-LA with a second long-acting agent (cabotegravir) administered intramuscularly every 4--8 weeks was similar in virologic suppression rates to standard of care ARV treatment.

SUMMARY

RPV-LA is an injectable nanoparticle suspension for intramuscular use. Phase I studies in healthy volunteers demonstrated that RPV-LA, administered at doses between 600 and 1200 mg, was well tolerated and effective in maintaining satisfactory drug concentrations in plasma, vaginal secretions and rectal tissue compartments for at least 4 weeks. RPV-LA efficacy was also shown in a phase II clinical trial in HIV infected patients and phase III studies are currently ongoing. Most study participants stated that they would use or continue using injectables, both in HIV treatment and prevention settings. Long-acting injectable ARVs have the potential to improve the convenience of HIV drug regimens.

Prevalence of predicted resistance to doravirine in HIV-1-positive patients after exposure to non-nucleoside reverse transcriptase inhibitors

This study investigated the prevalence of doravirine (DOR) resistance mutations in non-nucleoside reverse transcriptase inhibitor (NNRTI)-experienced patients. DOR resistance was assessed in samples from NNRTI-experienced patients who underwent genotypic testing for virological failure from the Antiretroviral Response Cohort Analysis (ARCA) database. Intermediate DOR resistance was defined as detection of any of V106A/M, Y188C/H, V108I, and K103N+P225H. High-level DOR resistance was defined as detection of any of Y188L, M230L, G190E, V106A/M+F227L, and V106A/M+L234I. Overall, 6893 patients were included in the study: 64.2% had experienced efavirenz (EFV), 54.4% nevirapine (NVP), 6.8% etravirine (ETR), 7.7% rilpivirine (RPV) and 0.7% delavirdine. Among NNRTI-experienced patients, 12.7% and 6.1% of subjects had intermediate and high-level DOR resistance, respectively. The most common DOR resistance mutation was Y188L. In multivariable analysis, previous EFV use (OR = 1.52, 95% CI 1.15-2.02) and ETR use (OR = 1.91, 95% CI 1.34-2.73) were associated with detection of high-level DOR resistance, whilst RPV use was associated with a lower probability of high-level DOR resistance (OR = 0.39, 95% CI 0.22-0.71). Moreover, EFV use (OR = 1.76, 95% CI 1.19-2.58) and ETR use (OR = 1.72, 95% CI 1.10-2.68) were associated with detection of the Y188L mutation, whereas RPV use was not (OR = 0.16, 95% CI 0.05-0.50). In Italy, DOR resistance is uncommon among NNRTI-experienced patients, confirming a distinguishing resistance pattern within NNRTIs. However, previous EFV and ETR experience poses a higher risk of DOR resistance. These results support the use of DOR in NNRTI-experienced patients.

The Journey of HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) from Lab to Clinic

Human immunodeficiency virus (HIV) infection is now pandemic. Targeting HIV-1 reverse transcriptase (HIV-1 RT) has been considered as one of the most successful targets for the development of anti-HIV treatment. Among the HIV-1 RT inhibitors, non-nucleoside reverse transcriptase inhibitors (NNRTIs) have gained a definitive place due to their unique antiviral potency, high specificity, and low toxicity in antiretroviral combination therapies used to treat HIV. Until now, >50 structurally diverse classes of compounds have been reported as NNRTIs. Among them, six NNRTIs were approved for HIV-1 treatment, namely, nevirapine (NVP), delavirdine (DLV), efavirenz (EFV), etravirine (ETR), rilpivirine (RPV), and doravirine (DOR). In this perspective, we focus on the six NNRTIs and lessons learned from their journey through development to clinical studies. It demonstrates the obligatory need of understanding the physicochemical and biological principles (lead optimization), resistance mutations, synthesis, and clinical requirements for drugs.

Doravirine versus ritonavir-boosted darunavir in antiretroviral-naive adults with HIV-1 (DRIVE-FORWARD): 48-week results of a randomised, double-blind, phase 3, non-inferiority trial

BACKGROUND

Doravirine is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) with a pharmacokinetic profile supporting once-daily dosing, and potent in-vitro activity against the most common NNRTI-resistant HIV-1 variants. We compared doravirine with ritonavir-boosted darunavir, when both were given with two nucleoside reverse transcriptase inhibitors (NRTIs), in adults with previously untreated HIV-1 infection.

METHODS

In this randomised, controlled, double-blind, multicentre, non-inferiority trial, adults with HIV-1 infection were screened and enrolled at 125 clinical centres in 15 countries. Eligible participants (aged ≥18 years) were naive to antiretroviral therapy with plasma HIV-1 RNA of at least 1000 copies per mL at screening. Participants who had previously been treated for a viral infection other than HIV-1, those taking immunosuppressive drugs, and individuals with active acute hepatitis were excluded. Participants were randomly assigned (1:1) via an interactive voice and web response system to receive oral doravirine 100 mg or darunavir 800 mg plus ritonavir 100 mg once daily, with two investigator-selected NRTIs (tenofovir and emtricitabine or abacavir and lamivudine) for up to 96 weeks. Randomisation was stratified by HIV-1 RNA measurements at screening (≤100 000 vs >100 000 copies per mL) and the NRTI pair. Study participants, funding institution staff, investigators, and study site personnel were masked to treatment group assignment. The primary efficacy endpoint was the proportion of participants achieving HIV-1 RNA of less than 50 copies per mL at week 48 defined by the US Food and Drug Administration snapshot algorithm, with non-inferiority established if the lower bound of the two-sided 95% CI for the treatment difference (doravirine minus darunavir) was greater than -10 percentage points. All participants who received at least one dose of study drug were included in the primary efficacy and safety analyses. This trial is active, but not recruiting, and is registered with ClinicalTrials.gov, number NCT02275780.

FINDINGS

Between Dec 1, 2014, and Oct 20, 2015, 1027 participants were screened for eligibility, of whom 769 participants were randomly assigned to treatment (385 with doravirine and 384 with ritonavir-boosted darunavir). 56 participants discontinued treatment in the doravirine group compared with 71 in the darunavir group, mostly due to loss to follow-up. 383 participants who received doravirine and 383 who received darunavir were included in the primary efficacy analyses. At week 48, 321 (84%) participants in the doravirine group and 306 (80%) in the darunavir group achieved plasma HIV-1 RNA of less than 50 copies per mL (difference 3·9%, 95% CI -1·6 to 9·4), indicating non-inferiority of the doravirine regimen. The most common study drug-related adverse events were diarrhoea (21 [5%] of 383 participants in the doravirine group and 49 [13%] of 383 participants in the darunavir group), nausea (25 [7%] vs 29 [8%]), and headache (23 [6%] vs ten [3%]). 18 participants (six [2%] of 383 participants in the doravirine group vs 12 [3%] of 383 participants in the darunavir group) discontinued treatment due to adverse events, which were considered drug-related in four (1%) participants in the doravirine group and 8 (2%) participants in the darunavir group. Serious adverse events occurred in 19 (5%) of 383 participants in the doravirine group and 23 (6%) of 383 in the darunavir roup, and were considered study-drug related in one (<1%) participant of each group.

INTERPRETATION

In treatment-naive adults with HIV-1 infection, doravirine combined with two NRTIs might offer a valuable treatment option for adults with previously untreated HIV-1 infection.

FUNDING

Merck & Co.

Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors: A Combinatorial Approach

Highly active antiretroviral therapy (HAART) is one of the most effective means for fighting against HIV-infection. HAART primarily targets HIV-1 reverse transcriptase (RT), and 14 of 28 compounds approved by the FDA as anti-HIV drugs act on this enzyme. HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) hold a special place among HIV RT inhibitors owing to their high specificity and unique mode of action. Nonetheless, these drugs show a tendency to decrease their efficacy due to high HIV-1 variability and formation of resistant virus strains tolerant to clinically applied HIV NNRTIs. A combinatorial approach based on varying substituents within various fragments of the parent molecule that results in development of highly potent compounds is one of the approaches aimed at designing novel HIV NNRTIs. Generation of HIV NNRTIs based on pyrimidine derivatives explicitly exemplifies this approach, which is discussed in this review.

Development and Validation of a Chromatographic Ultraviolet Method for the Simultaneous Quantification of Dolutegravir and Rilpivirine in Human Plasma

BACKGROUND

We have developed and validated a high-performance liquid chromatographic method for the simultaneous quantification, in human plasma, of dolutegravir, a new human immunodeficiency virus (HIV) integrase inhibitor, and rilpivirine, a novel HIV nonnucleoside reverse transcriptase inhibitor.

METHODS

An internal standard (quinoxaline) was added to plasma aliquots (500 μL), and a simple solid-phase extraction procedure was applied. Chromatographic separation of the drugs and internal standard was achieved with a gradient of acetonitrile and acetate buffer, and with an analytical run time of 25 minutes using an XBridge C18 column. The column eluate was monitored at 260 nm for dolutegravir and the internal standard and at 305 nm for rilpivirine.

RESULTS

The method was linear in the range of 20-8000 and 20-2000 ng/mL for dolutegravir and rilpivirine, respectively (mean r ≥ 0.993 on 10 replicates for both analytes). Mean intraday and interday precision and inaccuracy were <15% for both compounds. The mean recovery was 73% and 80% for dolutegravir and rilpivirine, respectively.

CONCLUSIONS

The high-performance liquid chromatography-ultraviolet method we developed showed a good analytical performance required for therapeutic drug monitoring of antiretrovirals, leading to potential improvements in HIV-infected patient care and laboratory management.

Drug-like property-driven optimization of 4-substituted 1,5-diarylanilines as potent HIV-1 non-nucleoside reverse transcriptase inhibitors against rilpivirine-resistant mutant virus

On the basis of our prior structure-activity relationship (SAR) results, our current lead optimization of 1,5-diarylanilines (DAANs) focused on the 4-substituent (R1) on the central phenyl ring as a modifiable position related simultaneously to improved drug resistance profiles and drug-like properties. Newly synthesized p-cyanovinyl-DAANs (8a-8g) with different R1 side chains plus prior active p-cyanoethyl-DAANs (4a-4c) were evaluated not only for anti-HIV potency against both wild-type HIV virus and rilpivirine-resistant (E138K, E138K+M184I) viral replication, but also for multiple drug-like properties, including aqueous solubility, lipophilicity, and metabolic stability in human liver microsomes and human plasma. This study revealed that both ester and amide R1 substituents led to low nanomolar anti-HIV potency against wild-type and rilpivirine-resistant viral strains (E138K-resistance fold changes<3). The N-substituted amide-R1 side chains were superior to ester-R1 likely due to improved aqueous solubility, lipophilicity, and higher metabolic stability in vitro. Thus, three amide-DAANs 8e, 4a, and 4b were identified with high potency against wild-type and rilpivirine-resistant viral strains and multiple desirable drug-like properties.

Long-acting rilpivirine as potential pre-exposure prophylaxis for HIV-1 prevention (the MWRI-01 study): an open-label, phase 1, compartmental, pharmacokinetic and pharmacodynamic assessment

BACKGROUND

Long-acting injectable antiretroviral agents are being developed for HIV-1 prevention. The MWRI-01 study was done to characterise the safety, acceptability, and pharmacokinetic and pharmacodynamic profile of long-acting rilpivirine.

METHODS

We did a phase 1 open-label study at the University of Pittsburgh. We enrolled healthy individuals (aged 18-45 years) who were seronegative for HIV-1. Participants were assigned alternately one intramuscular dose of either 1200 mg or 600 mg long-acting rilpivirine, beginning with the 1200 mg dose. We obtained plasma specimens, genital and rectal fluids, and tissue samples (rectal, cervical, and vaginal) before and after exposure to long-acting rilpivirine for assessment of pharmacokinetics and ex-vivo biopsy challenge with HIV-1. Our primary objective was to characterise product safety, and the analysis included all enrolled participants. This trial is registered with ClinicalTrials.gov, number NCT01656018.

FINDINGS

36 participants were enrolled into the study, of whom 24 were women and 12 men. 12 women and six men received each dose. 204 adverse events were reported among the 36 participants, of which 200 (98%) were grade 1-2. The most common adverse event was injection site reaction. All grade 3 and 4 adverse events were deemed not related to rilpivirine. Geometric mean (90% CI) concentrations in plasma of rilpivirine at day 28 post dose were 53 ng/mL (38-67) in women and 43 ng/mL (23-63) in men for the 1200 mg dose and 28 ng/mL (19-37) in women and 17 ng/mL (9-24) in men for the 600 mg dose. The tissue-to-plasma ratio for rilpivirine in rectal tissue was about two-fold higher than in vaginal and cervical tissue (1·10-1·53 vs 0·61-0·72 and 0·50-0·71, respectively). Exposure to long-acting rilpivirine suppressed viral replication significantly in rectal tissue (p<0·0001), and this suppression persisted for up to 4 months. By contrast, no viral suppression was seen in cervical or vaginal tissue.

INTERPRETATION

Ongoing research will characterise longer term safety and acceptability of multiple injections and help ascertain whether long-acting rilpivirine should advance to assessment of efficacy in preventing HIV-1 infection.

FUNDING

Bill & Melinda Gates Foundation.

Pharmacokinetics of Rilpivirine in HIV-Infected Pregnant Women

BACKGROUND

Rilpivirine pharmacokinetics is defined by its absorption, distribution, metabolism, and excretion. Pregnancy can affect these factors by changes in cardiac output, protein binding, volume of distribution, and cytochrome P450 (CYP) 3A4 activity. Rilpivirine is metabolized by CYP3A4. The impact of pregnancy on rilpivirine pharmacokinetics is largely unknown.

METHODS

International Maternal Pediatric Adolescent AIDS Clinical Trials P1026s is a multicenter, nonblinded, prospective study evaluating antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving rilpivirine 25 mg once daily as part of their combination antiretrovirals for clinical care. Thirty-two women were enrolled in this study. Intensive pharmacokinetic sampling was performed at steady state during the second trimester, the third trimester, and postpartum. Maternal and umbilical cord blood samples were obtained at delivery. Plasma rilpivirine concentration was measured using liquid chromatography-mass spectrometry; lower limit of quantitation was 10 ng/mL.

RESULTS

Median (range) AUC0-24 were 1969 (867-4987, n = 15), 1669 (556-4312, n = 28), and 2387 (188-6736, n = 28) ng·h/mL in the second trimester, the third trimester, and postpartum, respectively (P < 0.05 for either trimester vs postpartum). Median (range) C24 were 63 (37-225, n = 17), 56 (<10-181, n = 30), and 81 (<10-299, n = 28) ng/mL (P < 0.05 for either trimester vs postpartum). High variability in pharmacokinetic parameters was observed between subjects. Median (range) cord blood/maternal concentration ratio was 0.55 (0.3-0.8, n = 21). Delivery HIV-1 RNA was ≤50 copies per milliliter in 70% and ≤400 copies per milliliter in 90% of women. Cmin were significantly lower at 15 visits with detectable HIV-1 RNA compared with 61 visits with undetectable HIV-1 RNA, 29 (<10-93) vs 63 (15-200) ng/mL (P = 0.0001). Cmin was below the protein binding-adjusted EC90 concentration (12.2 ng/mL) at 4 visits in 3 of 31 women (10%).

CONCLUSIONS

Rilpivirine exposure is lower during pregnancy compared with postpartum and highly variable. Ninety percent of women had minimum concentrations above the protein binding-adjusted EC90 for rilpivirine.

Structural optimization of pyridine-type DAPY derivatives to exploit the tolerant regions of the NNRTI binding pocket

Based on the crystallographic studies of diarylpyrimidines (DAPYs), we embarked on incorporating the hydrophilic piperidyl or morpholinyl group into the known DAPY derivatives bearing the pyridine moiety as a core structure, with the double aim to exploit additional interactions with the HIV-1 NNRTI binding pocket (NNIBP), as well as to improve the compound solubility. The antiviral evaluation result show that the most potent compounds I-8b2, I-8b3, I-8b4 and I-8c3 exhibited anti-HIV-1 (IIIB) strain activity ranging from 7.4 nM to 9.4 nM (SI = 168-1283), superior to FDA-approved drugs of nevirapine (NVP), lamivudine (3TC) and delavirdine (DLV), and comparable to etravirine (ETV), zidovudine (AZT) and efavirenz (EFV). Additionally, compounds I-8c2 and I-8c3 showed moderate activity against NNRTI resistant strains baring mutations K103N and Y181C with EC50 values of 6.2 μM and 6.8 μM, respectively. Preliminary structure-activity relationships (SARs), reverse transcriptase inhibition efficacy and molecular modeling of selected compounds are also presented. These outcomes support our design hypothesis and demonstrate that the piperidyl group modified pyridine-typed DAPY derivatives are highly potent NNRTIs with improved water solubility.

Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitor Agents: Optimization of Diarylanilines with High Potency against Wild-Type and Rilpivirine-Resistant E138K Mutant Virus

Three series (6, 13, and 14) of new diarylaniline (DAAN) analogues were designed, synthesized, and evaluated for anti-HIV potency, especially against the E138K viral strain with a major mutation conferring resistance to the new-generation non-nucleoside reverse transcriptase inhibitor drug rilpivirine (1b). Promising new compounds were then assessed for physicochemical and associated pharmaceutical properties, including aqueous solubility, log P value, and metabolic stability, as well as predicted lipophilic parameters of ligand efficiency, ligand lipophilic efficiency, and ligand efficiency-dependent lipophilicity indices, which are associated with ADME property profiles. Compounds 6a, 14c, and 14d showed high potency against the 1b-resistant E138K mutated viral strain as well as good balance between anti-HIV-1 activity and desirable druglike properties. From the perspective of optimizing future NNRTI compounds as clinical trial candidates, computational modeling results provided valuable information about how the R(1) group might provide greater efficacy against the E138K mutant.

Long-acting rilpivirine for HIV prevention

PURPOSE OF REVIEW

Long-acting injectable antiretroviral (ARV) formulations are being developed for the treatment and prevention of HIV infection. The purpose of this review is to summarize recent preclinical and clinical data on TMC278 (rilpivirine), a nonnucleoside reverse transcriptase inhibitor (NNRTI), that is being developed for both a treatment and prevention indication.

RECENT FINDINGS

Long-acting rilpivirine has demonstrated efficacy in preventing HIV acquisition in a humanized mouse model and has been found to be well tolerated and acceptable in several Phase I clinical trials. Pharmacokinetic data from Phase I studies suggest that 1200 mg of long-acting rilpivirine administered every 8 weeks would be associated with plasma and tissue levels of rilpivirine anticipated to be necessary for preventing HIV infection. This regimen is being evaluated in the HPTN-076 Phase II expanded safety study that will enroll women in South Africa, Zimbabwe, and the USA. The HPTN-076 study requires a 4-week run in with oral rilpivirine (25 mg capsules) before receiving 1200 mg of rilpivirine. It is not yet certain whether oral dosing will remain a prerequisite in future trials or post licensure.

SUMMARY

Long-acting rilpivirine shows promise as a candidate agent for HIV prevention. Preclinical efficacy has been demonstrated in a murine model. Phase I studies have shown good safety and efficacy, but breakthrough infection and resistance have been documented with lower doses of long-acting rilpivirine. Phase II development for a prevention indication is ongoing.

Resistance and cross-resistance profile of the diaryltriazine NNRTI and candidate microbicide UAMC01398

OBJECTIVES

The resistance development, cross-resistance to other NNRTIs and the impact of resistance on viral replicative fitness were studied for the new and potent NNRTI UAMC01398.

METHODS

Resistance was selected by dose escalation and by single high-dose selection against a comprehensive panel of NNRTIs used as therapeutics and NNRTIs under investigation for pre-exposure prophylaxis of sexual HIV transmission. A panel of 27 site-directed mutants with single mutations or combinations of mutations involved in reverse transcriptase (RT) inhibitor-mediated resistance was developed and used to confirm resistance to UAMC01398. Cross-resistance to other NNRTIs was assessed, as well as susceptibility of UAMC01398-resistant HIV to diarylpyrimidine-resistant viruses. Finally, the impact of UAMC01398 resistance on HIV replicative fitness was studied.

RESULTS

We showed that UAMC01398 has potent activity against dapivirine-resistant HIV, that at least four mutations in the RT are required in concert for resistance and that the resistance profile is similar to rilpivirine, both genotypically and phenotypically. Resistance development to UAMC01398 is associated with a severe fitness cost.

CONCLUSIONS

These data, together with the enhanced safety profile and good solubility in aqueous gels, make UAMC01398 an excellent candidate for HIV topical prevention.

Systematic review to determine the prevalence of transmitted drug resistance mutations to rilpivirine in HIV-infected treatment-naive persons

BACKGROUND

Transmitted drug resistance to antiretrovirals in HIV-1-infected individuals is rising in some regions and could compromise the effectiveness of first-line treatment. It is important to understand the prevalence of resistance to rilpivirine to inform treatment provision.

METHODS

A PUBMED/EMBASE search identified analyses of transmitted genotypic resistance to specific non-nucleoside reverse transcriptase inhibitor mutations worldwide. Patients were to be HIV-1-infected and antiretroviral-naive. Rilpivirine mutations assessed were: L100I, K101E/P, E138A/G/K/Q/R, V179L, Y181C/I/V, Y188L, H221Y, F227C and M230I/L. Additionally, frequency of resistance mutations were extracted and pooled by HIV subtype from the Stanford HIV drug resistance database.

RESULTS

138 eligible articles from 65 countries were identified (n=64,466). Among these 64,466 samples, 7 of the 9 genotypic rilpivirine mutations had a prevalence <0.1%. Two mutations were more prevalent: E138A/G/K/Q/R (0.7%, 95% CI 0.2, 1.3) and Y181C/I/V (0.3%, 95% CI 0.2, 0.4). Prevalence of E138 rilpivirine-related mutations varied between regions: highest in Latin America/Caribbean (3.6%, 95% CI 1.0, 7.6) and in Europe (3.2%, 95% CI 0.7, 6.9). Pooled results from the Stanford database (n=52,680) correlated with these findings indicating a low prevalence of 8/9 rilpivirine mutations (<0.1%), except for E138A/G/K/Q/R (2.9%, 95% CI 1.8, 4.4). Prevalence of the mutations at E138 varied significantly by HIV subtype and was highest for subtype-C (6.1%), subtype-F (5.1%) and subtype-A (3.3%).

CONCLUSIONS

The prevalence of most transmitted rilpivirine-related HIV mutations is generally low in treatment-naive HIV-1-infected individuals (<0.1%). The prevalence of E138A/G/K/Q/R mutations is higher (0.7%) and varies according to geographical region and HIV subtype.

A randomized, double-blind, placebo-controlled, short-term monotherapy study of doravirine in treatment-naive HIV-infected individuals

OBJECTIVE

To assess the antiviral activity, pharmacokinetics, and safety of doravirine in nonnucleoside reverse transcriptase inhibitor-naïve, HIV-infected men.

DESIGN

Double-blind, randomized, two-panel, dose-escalation study.

METHODS

In two sequential panels, 18 individuals received doravirine [25 mg (Panel A) or 200 mg (Panel B)] or matching placebo once daily for 7 days. Plasma samples were collected daily for measurement of HIV-1 RNA levels and doravirine pharmacokinetics.

RESULTS

For the mean change from baseline in HIV RNA (log10 copies/ml) at 24 h after the day 7 dose, the mean difference (90% confidence interval) between doravirine and placebo was -1.37 (-1.60, -1.14) in the 25-mg group and -1.26 (-1.51, -1.02) in the 200-mg group. None of the participants had viral breakthrough. Increases in mean AUC0-24 h, Cmax, and C24 h were slightly less than dose-proportional, with median Tmax of 1.0-2.0 h. Steady state was achieved after 3-5 days of once-daily dosing. At steady state, accumulation ratios (day 7/day 1) for AUC0-24 h, Cmax, and C24 h were 1.2-1.6. The calculated effective t1/2 (10-16 h) was similar to that in HIV-uninfected individuals. Adverse events were limited in number, transient, and generally mild to moderate in intensity. One participant had a serious adverse event of elevated liver enzymes (judged probably not drug related) in concurrence with a newly acquired hepatitis C infection.

CONCLUSION

Doravirine monotherapy demonstrated robust antiviral activity at both dose levels, without evidence of viral resistance, and was generally well tolerated. Doravirine pharmacokinetics in HIV-infected individuals were similar to those in uninfected individuals receiving similar doses in prior studies.

Antiviral Drugs

Viruses are major pathogenic agents causing a variety of serious diseases in humans, other animals, and plants.

Drugs that combat viral infections are called antiviral drugs. There are no effective antiviral drugs for many viral infections. However, there are several drugs for influenza, a couple of drugs for herpesviruses, and some new antiviral drugs for treatment of HIV and hepatitis C infections.

The arsenal of antivirals is complex. As of March 2014, it consists of approximately 50 drugs approved by the FDA, approximately half of which are directed against HIV. Antiviral drug creation strategies are focused on two different approaches: targeting the viruses themselves or targeting host cell factors.

Direct virus-targeting antiviral drugs include attachment inhibitors, entry inhibitors, uncoating inhibitors, protease inhibitors, polymerase inhibitors, nucleoside and nucleotide reverse transcriptase inhibitors, nonnucleoside reverse-transcriptase inhibitors, and integrase inhibitors.

Protease inhibitors (darunavir, atazanavir, and ritonavir), viral DNA polymerase inhibitors (acyclovir, valacyclovir, valganciclovir, and tenofovir), and an integrase inhibitor (raltegravir) are included in the list of Top 200 Drugs by sales for the 2010s.

Injectable and implantable antiretroviral strategies for HIV prevention

Antiretroviral preexposure prophylaxis has huge potential for reducing the rates of new HIV infections in at risk populations. Oral and vaginal antiretroviral formulations have been evaluated in multiple Phase IIB and Phase III effectiveness trials and there is clear evidence that these products work when used. The converse is also true; antiretrovirals do not work when they are not used and unfortunately adherence is a problem for both HIV treatment and prevention. As a consequence, long-acting injectable and implantable antiretroviral formulations are being developed for the treatment and prevention of HIV infection. It is hoped they will reduce the burden of product adherence associated with the use of oral and topical products and improve clinical outcomes associated with their use. The purpose of this review is to summarize recent preclinical and clinical research in this area of HIV prevention.

Dual antiviral therapy for HIV and hepatitis C - drug interactions and side effects

INTRODUCTION

Roughly 20% of HIV-positive persons worldwide are coinfected with hepatitis C virus (HCV). The recent advent of direct-acting antivirals (DAA) that cure most hepatitis C patients has attracted much attention. Knowledge on drug interactions between DAA and antiretrovirals (ARV) may allow maximizing antiviral efficacy while minimizing drug-related toxicities.

AREAS COVERED

We review the most frequent side effects and clinically significant drug interactions between DAA and ARV. We further discuss how they can be prevented and managed in HIV/HCV-coinfected patients.

EXPERT OPINION

The safety profile of current DAA and the most recently approved ARV is quite favorable. Interactions between DAA and ARV could be frequent in clinical practice. The most common drug interactions affect drug metabolism by inducing or inhibiting the cytochrome P450 system, leading to abnormal drug exposures. Throughout this mechanism HCV and HIV protease inhibitors interact, especially when co-formulated with ritonavir as a pharmacoenhancer, and non-nucleoside HCV and HIV polymerase inhibitors. In contrast, HIV and HCV nucleos(t)ide polymerase inhibitors, and most HCV NS5A inhibitors (i.e., ledipasvir) and HIV integrase inhibitors (i.e., dolutegravir), do not or only marginally affect CYP450, and therefore are free of significant drug interactions. Exposure to HIV and HCV nucleos(t)ide analogues (i.e., tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters (i.e., P-glycoprotein).