Efficacy and safety of lersivirine (UK-453,061) versus efavirenz in antiretroviral treatment-naive HIV-1-infected patients: week 48 primary analysis results from an ongoing, multicenter, randomized, double-blind, phase IIb trial

Nonclinical Safety Profile of Sotorasib, a KRASG12C-Specific Covalent Inhibitor for the Treatment of KRAS p.G12C-Mutated Cancer

Sotorasib is a first-in-class KRAS^G12C covalent inhibitor in clinical development for the treatment of tumors with the KRAS p.G12C mutation. A comprehensive nonclinical safety assessment package, including secondary/safety pharmacology and toxicology studies, was conducted to support the marketing application for sotorasib. Sotorasib was negative in a battery of genotoxicity assays and negative in an in vitro phototoxicity assay. Based on in vitro assays, sotorasib had no off-target effects against various receptors, enzymes (including numerous kinases), ion channels, or transporters. Consistent with the tumor-specific target distribution (ie, KRAS^G12C), there were no primary pharmacology-related on-target effects identified. The kidney was identified as a target organ in the rat but not the dog. Renal toxicity in the rat was characterized by tubular degeneration and necrosis restricted to a specific region suggesting that the toxicity was attributed to the local formation of a putative toxic reactive metabolite. In the 3-month dog study, adaptive changes of hepatocellular hypertrophy due to drug metabolizing enzyme induction were observed in the liver that was associated with secondary effects in the pituitary and thyroid gland. Sotorasib was not teratogenic and had no direct effect on embryo-fetal development in the rat or rabbit. Human, dog, and rat circulating metabolites, M24, M10, and M18, raised no clinically relevant safety concerns based on the general toxicology studies, primary/secondary pharmacology screening, an in vitro human ether-à-go-go-related gene assay, or mutagenicity assessment. Overall, the results of the nonclinical safety program support a high benefit/risk ratio of sotorasib for the treatment of patients with KRAS p.G12C-mutated tumors.

A model-based comparative meta-analysis of the efficacy of dolutegravir-based and efavirenz-based regimens in HIV-infected patients

Currently, combinations of typical types of antiretroviral agents have been adopted as chemotherapy for human immunodeficiency virus (HIV) infection, comprising two nucleoside analogue reverse transcriptase inhibitors plus one of a non-nucleoside reverse transcriptase inhibitor, an integrase strand-transfer inhibitor, and a protease inhibitor. Although several meta-analyses have been conducted to determine first-line combination antiretroviral therapy, this has yet to be confirmed due to the technical limitation associated. In the present study, we applied a model-based meta-analysis (MBMA) approach, because it allows integration of information from clinical trials with varying dosing, duration, and sampling time points, resulting in enlargement of available data sources. We performed a bibliographic search to identify clinical trials involving dolutegravir (DTG)-based and efavirenz (EFV)-based regimens in HIV-infected, antiretroviral therapy-naïve adults, and then identified 30 independent trial data. The time course of drug effect was described by a consecutive first-order kinetic model and analyzed using the nonlinear mixed effect modeling approach. The developed model suggests that the DTG-based regimen provides a faster-acting and more sustainable drug effect than the EFV-based regimen. Moreover, the drug effect tends to appear more slowly and decay faster in severe patients having higher viral load or smaller baseline CD4 count.

A facile one-pot multi-component synthesis of novel adamantine substituted imidazo[1,2-a]pyridine derivatives: identification and structure–activity relationship study of their anti-HIV-1 activity

A series of adamantine substituted imidazo[1,2-a]pyridine derivatives were developed through a one-pot multi-component Groebke–Blackburn–Bienaymé reaction, among them several compounds were identified to be the potent inhibitors against HIV-1 cells.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

Investigational reverse transcriptase inhibitors for the treatment of HIV

INTRODUCTION

While considerable advances have been made in the development of antiretroviral agents, there is still work to be done. Reverse transcriptase inhibitors are important drugs for the treatment of HIV, and considerable research is currently ongoing to develop new agents and to modify currently existing agents.

AREAS COVERED

Herein, the authors discuss both investigational nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), including agents that are in various stages of development. They also discuss novel formulations that are being investigated for currently available drugs, and discuss the advantages that these new formulations may provide.

EXPERT OPINION

New formulations and co-formulations of currently existing antiretrovirals will represent an important area of development, as a means to improve adherence for HIV-positive individuals. New formulations will continue to be developed, with a focus on allowing for less-frequent administration, as well increasing drug concentrations at local sites such as vaginal tissue, rectal tissue and sites in the immune system.

Efavirenz-Based Regimens in Antiretroviral-Naive HIV-Infected Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Efavirenz, a non-nucleoside reverse-transcriptase inhibitor (NNRTI) is one of the most commonly prescribed antiretroviral drugs. The present article provides a systematic overview and meta-analysis of clinical trials comparing efavirenz and other active drugs currently recommended for treatment of HIV-infected, antiretroviral-naive patients. Electronic databases (Pubmed, Embase, the Cochrane Library, Trip Database) were searched up till 23 December 2013 for randomized controlled clinical trials published as a peer-reviewed papers, and concerning efavirenz-based regimens used as initial treatment for HIV infection. Thirty-four studies were included in the systematic review, while twenty-six trials were suitable for the meta-analysis. Efavirenz was compared with drugs from four different classes: NNRTIs other than efavirenz (nevirapine or rilpivirine), integrase strand transfer inhibitors (InSTIs), ritonavir-boosted protease inhibitors (bPI) and chemokine (C-C motif) receptor 5 (CCR5) antagonists (maraviroc), all of them were added to the background regimen. Results of the current meta-analysis showed that efavirenz-based regimens were equally effective as other recommended regimens based on NNRTI, ritonavir-boosted PI or CCR5 antagonist in terms of efficacy outcomes (disease progression and/or death, plasma viral HIV RNA <50 copies/ml) while statistically significant more patients treated with InSTI achieved plasma viral load <50 copies/ml at week 48. In comparison with both InSTI-based and CCR5-based therapy, efavirenz-based treatment was associated with a higher risk of therapy discontinuation due to adverse events. However, comparisons of efevirenz-based treatment with InSTI-based and CCR5-based therapy were based on a limited number of trials, therefore, conclusions from these two comparisons must be confirmed in further reliable randomized controlled studies. Results of our meta-analysis support the present clinical guidelines for antiretroviral-naive, HIV-infected patients, in which efavirenz is one of the most preferred regimens in the analyzed population. Beneficial safety profile of InSTI-based and CCR5-based therapy over efavirenz-based treatment needs further studies.

Efficacy and safety of lersivirine versus etravirine for the treatment of HIV-1 infection in patients with prior non-nucleoside reverse transcriptase inhibitor (NNRTI) use and evidence of NNRTI resistance: a randomized phase 2B trial

OBJECTIVE

To assess the efficacy and safety of lersivirine versus etravirine in patients with HIV-1 and prior non-nucleoside reverse transcriptase inhibitor (NNRTI) use and evidence of NNRTI resistance.

METHODS

In this 96-week, phase 2b study, 97 patients were randomized and treated with lersivirine 750 mg qd (n = 31), lersivirine 1,000 mg qd (n = 32), and etravirine 200 mg bid (n = 34), plus one optimized nucleoside reverse transcriptase inhibitor and darunavir/ritonavir 600/100 mg bid. The primary endpoint was the percentage of patients with HIV-1 RNA <50 copies/mL at week 24.

RESULTS

At week 24, HIV-1 RNA <50 copies/mL was achieved by fewer patients receiving lersivirine 750 mg (48.4%) and 1,000 mg (43.8%) qd compared with etravirine 200 mg qd (67.7%) (intention to treat [ITT], missing/switch/discontinuation equals failure [MSDF]). At week 48, HIV-1 RNA <50 copies/mL and <400 copies/mL were also achieved by fewer patients receiving lersivirine 750 mg (41.9% and 41.9%, respectively) and 1,000 mg (31.3% and 34.4%, respectively) qd compared with etravirine 200 mg bid (61.8% and 70.6%, respectively) (ITT, MSDF). Least squares means (SE) change from baseline in log transformed HIV-1 RNA at week 48 was -1.42 (0.27) and -0.95 (0.28) copies/mL for lersivirine 750 mg and 1,000 mg qd, respectively, versus -2.02 (0.26) copies/mL for etravirine 200 mg bid (ITT). Lersivirine and etravirine were generally safe and well-tolerated.

CONCLUSIONS

Lersivirine 750 mg and 1,000 mg qd was associated with lower rates of viral suppression at week 24 and week 48 versus etravirine in patients with prior NNRTI use and evidence of NNRTI resistance. No new safety signals were detected.

HIV-associated lipodystrophy: impact of antiretroviral therapy

In the late 1990s, reports of unusual changes in body fat distribution named 'lipodystrophy' (LD) began to appear in HIV patients mitigating the enormous enthusiasm about improvement of survival and quality of life provided by the combinations of antiretroviral (ARV) drug classes, the so-called highly active antiretroviral therapy (HAART), which had just become available at that time. The objective of this paper is to critically review the literature on LD and to discuss the impact of newer ARV agents, namely atazanavir, darunavir and raltegravir, as well as strategies of the late HAART era, including single-tablet regimens and nucleoside-sparing regimens. Studies in which LD was measured by dual-energy x-ray absorptiometry or by abdominal computed tomography or magnetic resonance imaging scan only, were included. We were unable to identify studies depicting a negative impact of drugs or ARV regimens on limb fat loss. On the contrary, a few studies identified a negative impact of atazanavir/ritonavir or darunavir/ritonavir on trunk fat increase. It should be noted that this anthropometric measure is a poor instrument since it cannot distinguish between subcutaneous and visceral fat. We conclude that presumably the body fat changes currently observed in HIV-infected patients is the net result of competing phenomena: on one side the natural history of lipohypertrophy as a result of HIV and HAART impact, and on the other side the physiological body fat changes observed in the aging population.

Clinical use of vaginal or rectally applied microbicides in patients suffering from HIV/AIDS

Microbicides, primarily used as topical pre-exposure prophylaxis, have been proposed to prevent sexual transmission of HIV. This review covers the trends and challenges in the development of safe and effective microbicides to prevent sexual transmission of HIV Initial phases of microbicide development used such surfactants as nonoxynol-9 (N-9), C13G, and sodium lauryl sulfate, aiming to inactivate the virus. Clinical trials of microbicides based on N-9 and C31G failed to inhibit sexual transmission of HIV. On the contrary, N-9 enhanced susceptibility to sexual transmission of HIV-1. Subsequently, microbicides based on polyanions and a variety of other compounds that inhibit the binding, fusion, or entry of virus to the host cells were evaluated for their efficacy in different clinical setups. Most of these trials failed to show either safety or efficacy for prevention of HIV transmission. The next phase of microbicide development involved antiretroviral drugs. Microbicide in the form of 1% tenofovir vaginal gel when tested in a Phase IIb trial (CAPRISA 004) in a coitally dependent manner revealed that tenofovir gel users were 39% less likely to become HIV-infected compared to placebo control. However, in another trial (VOICE MTN 003), tenofovir gel used once daily in a coitally independent mode failed to show any efficacy to prevent HIV infection. Tenofovir gel is currently in a Phase III safety and efficacy trial in South Africa (FACTS 001) employing a coitally dependent dosing regimen. Further, long-acting microbicide-delivery systems (vaginal ring) for slow release of such antiretroviral drugs as dapivirine are also undergoing clinical trials. Discovering new markers as correlates of protective efficacy, novel long-acting delivery systems with improved adherence in the use of microbicides, discovering new compounds effective against a broad spectrum of HIV strains, developing multipurpose technologies incorporating additional features of efficacy against other sexually transmitted infections, and contraception will help in moving the field of microbicide development forward.

Lersivirine - a new drug for HIV infection therapy

INTRODUCTION

Lersivirine (UK-453,061) is a novel second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI). It binds reverse transcriptase in a distinct way leading to a unique resistance profile. The development of lersivirine was recently stopped in Phase IIb clinical development.

AREAS COVERED

This article describes the background of lersivirine, its pharmacodynamic and pharmacokinetic profile and its clinical efficacy in HIV-infected patients. Moreover, the authors review its resistance profile in addition to its possible interactions with coadministered drugs and safety and tolerability. The authors' evaluation is based on the articles retrieved from a Medline in addition to abstracts from major HIV conferences and workshops addressing lersivirine.

EXPERT OPINION

The authors believe that lersivirine has therapeutic potential for HIV-infected individuals with viral strains resistant against first-line NNRTIs. However, no large, well-powered studies have been conducted so far, which assess noninferiority against established antiretroviral agents. In February 2013, the developing company behind lersivirine halted further development as it was decided that it would not provide an improvement over existing therapies; perhaps this is an opportunity missed.

Antiviral drug resistance and the need for development of new HIV-1 reverse transcriptase inhibitors

Highly active antiretroviral therapy (HAART) consists of a combination of drugs to achieve maximal virological response and reduce the potential for the emergence of antiviral resistance. Despite being the first antivirals described to be effective against HIV, reverse transcriptase inhibitors remain the cornerstone of HAART. There are two broad classes of reverse transcriptase inhibitor, the nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). Since the first such compounds were developed, viral resistance to them has inevitably been described; this necessitates the continuous development of novel compounds within each class. In this review, we consider the NRTIs and NNRTIs currently in both preclinical and clinical development or approved for second-line therapy and describe the patterns of resistance associated with their use as well as the underlying mechanisms that have been described. Due to reasons of both affordability and availability, some reverse transcriptase inhibitors with a low genetic barrier are more commonly used in resource-limited settings. Their use results in the emergence of specific patterns of antiviral resistance and so may require specific actions to preserve therapeutic options for patients in such settings.

A review of the virological efficacy of the 4 World Health Organization-recommended tenofovir-containing regimens for initial HIV therapy

We systematically reviewed studies of the virological efficacy of the 4 new tenofovir (TDF)-containing regimens recommended for initial antiretroviral (ARV) therapy in the 2010 World Health Organization ARV Treatment Guidelines. Thirty-three studies assessed the efficacy of 1 or more TDF-containing regimens: TDF/lamivudine (3TC)/nevirapine (NVP) (n = 3), TDF/ emtricitabine (FTC)/NVP (n = 9), TDF/3TC/efavirenz (EFV) (n = 6), and TDF/FTC/EFV (n = 19). TDF/3TC/NVP was the least well-studied and appeared the least efficacious of the 4 regimens. In 2 comparative studies, TDF/3TC/NVP was associated with significantly more virological failure than AZT/3TC/NVP; a third study was terminated prematurely because of early virological failure. TDF/FTC/NVP was either equivalent or inferior to its comparator arms. TDF/3TC/EFV was equivalent to its comparator arms. TDF/FTC/EFV was equivalent or superior to its comparator arms. Possible explanations for these findings include the greater antiviral activity of EFV versus NVP and longer intracellular half-life of FTC-triphosphate versus 3TC-triphosphate. Further study of TDF/3TC/NVP is required before it is widely deployed for initial ARV therapy.

Novel clinical trial designs for the development of new antiretroviral agents

The resounding success of combination antiretroviral efficacy for both treatment-naïve and treatment-experienced patients - with 70-90% viral suppression rates in recent studies - has made registration trials for new agents challenging. With the inevitable specter of drug resistance, new agents must have a pathway to approval. The Forum for Collaborative HIV Research obtained input from concerned stakeholders including industry, clinical sciences, community advocacy, and regulatory sciences (Food and Drug Administration and European Medicines Agency) to discuss how safety and efficacy of new agents could be demonstrated. Recognizing the shortfalls of superiority or noninferiority trials in this environment, a new trial design for treatment-experienced patients, minimizing the risk for drug resistance but allowing full assessment of safety, was proposed. The antiviral efficacy of an active investigational drug would be assessed by comparison to placebo as an add-on to a failing regimen in a short, 10-14-day study followed by institution of an optimized background regimen (OBR) in both arms with investigational drug given to all patients. The follow-on stage would assess dose response, safety, durability of initial response, and development of resistance. Additionally, a second safety trial could be conducted comparing patients randomized to the investigational agent with a new OBR to those on a new OBR and placebo. Finally, approval decisions could consider other long-term safety endpoints. Exposing treatment-naïve patients to investigational agents remains a controversial issue; stakeholders have different interpretations of risk-benefit for trials in this population that necessitate careful consideration before initiating trials in them.

Effects of ketoconazole and valproic acid on the pharmacokinetics of the next generation NNRTI, lersivirine (UK-453,061), in healthy adult subjects

AIMS

To investigate the effect of inhibitors of cytochrome P450 (CYP) 3A4 and glucuronidation (UGT2B7) on the pharmacokinetics of lersivirine (UK-453,061), a next generation non-nucleoside reverse transcriptase inhibitor with a unique resistance profile, and to investigate the safety and tolerability of co-administration of lersivirine with these inhibitors.

METHODS

Two open-label, randomized, placebo-controlled, crossover studies were conducted in healthy subjects. Study 1 investigated the effect of ketoconazole (400 mg once daily) on the pharmacokinetics of lersivirine (250 mg once daily). Subjects received ketoconazole 400 mg once daily or placebo on days 1-2 and received lersivirine 250 mg once daily and ketoconazole 400 mg once daily or placebo on days 3-9. Study 2 investigated the effect of valproic acid (VPA, sodium valproate, 1000 mg once daily) on the PK of lersivirine (500 mg once daily). On days 1-7, subjects received lersivirine 500 mg once daily plus either VPA 1000 mg or placebo.

RESULTS

Compared with lersivirine alone, co-administration with ketoconazole increased the lersivirine mean area under the curve (AUC(0,24 h)) and maximum plasma concentration (C(max) ) by 82% (90% CI 74%, 91%) and 61% (90% CI 41%, 83%), respectively. VPA increased the mean lersivirine AUC(0,24 h) by 25% (90% CI 16%, 35%), with little effect on C(max) (2.5%, 90% CI -9%, 16%). There were no serious adverse events and no treatment-related discontinuations from either study.

CONCLUSIONS

Inhibition of CYP3A4 and UGT2B7 by ketoconazole increased lersivirine exposure. Inhibition of UGT2B7-mediated glucuronidation by VPA had a modest effect on lersivirine exposure. Co-administration of lersivirine with either ketoconazole or VPA appeared to be well tolerated.