Safety, tolerability and impact on viral reservoirs of the addition to antiretroviral therapy of ABX464, an investigational antiviral drug, in individuals living with HIV-1: a Phase IIa randomised controlled study

Obefazimod: A First-in-class Drug for the Treatment of Ulcerative Colitis

Biologic agents and oral small molecules are the mainstays of inflammatory bowel disease [IBD] management. However, an unmet clinical need remains for additional agents with novel mechanism of action which are effective, safe, and disease-modifying; this is due to the substantial proportion of patients who do not respond, lose response, or develop intolerance to currently marketed products. microRNAs [miRNAs] that play a role in the modulation of signal transduction pathways implicated in the development of IBD hold the potential to be used as therapeutic targets. Recently, a novel first-in-class compound, obefazimod, originally conceived as a human immunodeficiency virus [HIV] infection drug, has shown great promise in phase II induction trials for ulcerative colitis [UC] patients. Findings from the maintenance phases of trials showed that long-term obefazimod treatment provides continued improvement in clinical symptoms of disease, with a substantial proportion of patients in clinical remission, and an overall good safety profile. With a novel mechanism of action, obefazimod is an orally available small molecule with anti-inflammatory properties through the specific and selective upregulation of miR-124 expression. The aim of this paper is to critically review the available evidence related to pharmacokinetics and pharmacodynamics, and to discuss the potential clinical implications of this first-in-class oral small molecule.

Impact of Obefazimod on Viral Persistence, Inflammation, and Immune Activation in People With Human Immunodeficiency Virus on Suppressive Antiretroviral Therapy

BACKGROUND

Persistence of viral reservoirs has been observed in people with human immunodeficiency virus (HIV), despite long-term antiretroviral therapy (ART), and likely contributes to chronic immune activation and inflammation. Obefazimod is a novel drug that inhibits human immunodeficiency virus type 1 (HIV-1) replication and reduces inflammation. Here we assess whether obefazimod is safe and might impact HIV-1 persistence, chronic immune activation, and inflammation in ART-suppressed people with HIV.

METHODS

We evaluated obefazimod-related adverse events, changes in cell-associated HIV-1 DNA and RNA, residual viremia, immunophenotype, and inflammation biomarkers in blood and rectal tissue. We compared 24 ART-suppressed people with HIV who received daily doses of 50 mg obefazimod for 12 weeks (n = 13) or 150 mg for 4 weeks (n = 11) and 12 HIV-negative individuals who received 50 mg for 4 weeks.

RESULTS

The 50- and 150-mg doses of obefazimod were safe, although the 150-mg dose showed inferior tolerability. The 150-mg dose reduced HIV-1 DNA (P = .008, median fold change = 0.6) and residual viremia in all individuals with detectable viremia at baseline. Furthermore, obefazimod upregulated miR-124 in all participants and reduced the activation markers CD38, HLA-DR, and PD-1 and several inflammation biomarkers.

CONCLUSIONS

The effect of obefazimod by reducing chronic immune activation and inflammation suggests a potential role for the drug in virus remission strategies involving other compounds that can activate immune cells, such as latency-reversing agents.

ABX464 (obefazimod) for patients with COVID-19 at risk for severe disease: miR-AGE, a randomized, double-blind placebo-controlled trial

Background

ABX464 (obefazimod) is a small molecule that upregulates a single microRNA (miR-124) in immune cells and reduces the production of various inflammatory cytokines and chemokines.

Objective

We assessed the efficacy and safety of the standard of care (SoC) plus oral obefazimod (SoC plus ABX464), 50 mg once daily, versus the SoC plus placebo for prevention of severe acute respiratory syndrome in patients with coronavirus disease 2019 (COVID-19) who are at risk for severe disease.

Methods

Eligible patients for this phase 2/3 double-blind, placebo-controlled miR-AGE study were randomized (2:1) into 2 groups: SoC-ABX464 (n = 339) and SoC-placebo (n = 170). The primary end point was the percentage of patients who did not require use of high-flow oxygen or invasive or noninvasive mechanical ventilation within 28 days. The safety analyses included patients who had been randomly assigned and had received at least 1 dose of the study treatment.

Results

At the time of the interim analysis, obefazimod showed no benefit over placebo when added to the SoC; the study enrollment was stopped for futility. The evaluation of the safety of obefazimod in 505 patients showed significantly more treatment-emergent adverse events in the SoC-ABX464 group than in the SoC-placebo group (P = .007). Frequently reported AEs in the SoC-ABX464 group included headache (14.6%), abdominal pain (9.6%), diarrhea (9.0%), back pain (6.9%), and nausea (6.0%). No treatment-related changes in laboratory parameters were reported.

Conclusion

For patients who have severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and are at risk for severe COVID-19, obefazimod, 50 mg, provided no benefit over placebo when added to the SoC, although it did have a good safety profile (comparable to that reported in many therapeutic areas).

New antiretroviral inhibitors and HIV-1 drug resistance: more focus on 90% HIV-1 isolates?

Combined HIV antiretroviral therapy (cART) has been effective except if drug resistance emerges. As cART has been rolled out in low-income countries, drug resistance has emerged at higher rates than observed in high income countries due to factors including initial use of these less tolerated cART regimens, intermittent disruptions in drug supply, and insufficient treatment monitoring. These socioeconomic factors impacting drug resistance are compounded by viral mechanistic differences by divergent HIV-1 non-B subtypes compared to HIV-1 subtype B that largely infects the high-income countries (just 10% of 37 million infected). This review compares the inhibition and resistance of diverse HIV-1 subtypes and strains to the various approved drugs as well as novel inhibitors in clinical trials. Initial sequence variations and differences in replicative fitness between HIV-1 subtypes pushes strains through different fitness landscapes to escape from drug selective pressure. The discussions here provide insight to patient care givers and policy makers on how best to use currently approved ART options and reduce the emergence of drug resistance in ∼33 million individuals infected with HIV-1 subtype A, C, D, G, and recombinants forms. Unfortunately, over 98% of the literature on cART resistance relates to HIV-1 subtype B.

MicroRNAs in T Cell-Immunotherapy

MicroRNAs (miRNAs) act as master regulators of gene expression in homeostasis and disease. Despite the rapidly growing body of evidence on the theranostic potential of restoring miRNA levels in pre-clinical models, the translation into clinics remains limited. Here, we review the current knowledge of miRNAs as T-cell targeting immunotherapeutic tools, and we offer an overview of the recent advances in miRNA delivery strategies, clinical trials and future perspectives in RNA interference technologies.

Non-nucleoside structured compounds with antiviral activity—past 10 years (2010–2020)

Nucleosides and their derivatives are a well-known and well-described class of compounds with antiviral activity. Currently, in the era of the COVID-19 pandemic, scientists are also looking for compounds not related to nucleosides with antiviral properties. This review aims to provide an overview of selected synthetic antiviral agents not associated to nucleosides developed against human viruses and introduced to preclinical and clinical trials as well as drugs approved for antiviral therapy over the last 10 years. The article describes for the first time the wide classification of such antiviral drugs and drug candidates and briefly summarizes the biological target and clinical applications of the compounds. The described compounds are arranged according to the antiviral mechanism of action. Knowledge of the drug's activity toward specific molecular targets may be the key to researching new antiviral compounds and repositioning drugs already approved for clinical use. The paper also briefly discusses the future directions of antiviral therapy. The described examples of antiviral compounds can be helpful for further drug development.

The Thiazole-5-Carboxamide GPS491 Inhibits HIV-1, Adenovirus, and Coronavirus Replication by Altering RNA Processing/Accumulation

Medicinal chemistry optimization of a previously described stilbene inhibitor of HIV-1, 5350150 (2-(2-(5-nitro-2-thienyl)vinyl)quinoline), led to the identification of the thiazole-5-carboxamide derivative (GPS491), which retained potent anti-HIV-1 activity with reduced toxicity. In this report, we demonstrate that the block of HIV-1 replication by GPS491 is accompanied by a drastic inhibition of viral gene expression (IC₅₀ ~ 0.25 µM), and alterations in the production of unspliced, singly spliced, and multiply spliced HIV-1 RNAs. GPS491 also inhibited the replication of adenovirus and multiple coronaviruses. Low µM doses of GPS491 reduced adenovirus infectious yield ~1000 fold, altered virus early gene expression/viral E1A RNA processing, blocked viral DNA amplification, and inhibited late (hexon) gene expression. Loss of replication of multiple coronaviruses (229E, OC43, SARS-CoV2) upon GPS491 addition was associated with the inhibition of viral structural protein expression and the formation of virus particles. Consistent with the observed changes in viral RNA processing, GPS491 treatment induced selective alterations in the accumulation/phosphorylation/function of splicing regulatory SR proteins. Our study establishes that a compound that impacts the activity of cellular factors involved in RNA processing can prevent the replication of several viruses with minimal effect on cell viability.

ABX464 decreases the total HIV reservoir and HIV transcription initiation in CD4 + T cells from HIV-infected ART-suppressed individuals

BACKGROUND

Antiretroviral therapy (ART) intensification and disruption of latency have been suggested as strategies to eradicate HIV. ABX464 is a novel antiviral that inhibits HIV RNA biogenesis. We investigated the effect of ABX464 on HIV transcription and total and intact HIV DNA in CD4 + T cells from ART-suppressed participants enrolled in the ABIVAX-005 clinical trial (NCT02990325).

METHODS

Peripheral CD4 + T cells were available for analysis from nine ART-suppressed participants who were treated daily with 150mg of ABX464 for 4 weeks. Total and intact HIV DNA, and initiated, 5'elongated, unspliced, polyadenylated and multiply-spliced HIV transcripts, were quantified at weeks 0, 4 and 8 using droplet digital PCR.

RESULTS

We observed a significant decrease in total HIV DNA (p=0.008, median fold-change=0.8) and a lower median level of intact HIV DNA (p=n.s., median fold-change=0.8) after ABX464 treatment (wk 0 vs. 4). Moreover, we observed a decrease in initiated HIV RNA per million CD4 + T cells and per provirus (p=0.05, median fold-change=0.7; p=0.004, median fold-change=0.5, respectively), a trend towards a decrease in the 5'elongated HIV RNA per provirus (p=0.07, median fold-change=0.5), and a lower median level of unspliced HIV RNA (p=n.s., median fold-change=0.6), but no decrease in polyadenylated or multiply-spliced HIV RNA.

CONCLUSION

In this substudy, ABX464 had a dual effect of decreasing total HIV DNA (and possibly intact proviruses) and decreasing the amount of HIV transcription per provirus. To further characterize its specific mechanism of inhibiting HIV transcription, long-term administration of ABX464 should be studied in a larger cohort.

Specific and selective induction of miR-124 in immune cells by the quinoline ABX464: a transformative therapy for inflammatory diseases

Inflammatory diseases are believed to develop as a result of dysregulated inflammatory responses to environmental factors on susceptible genetic backgrounds. Operating at the level of post-transcriptional gene regulation, miRNAs are a class of endogenous, small noncoding RNAs that can promote downregulation of protein expression by translational repression and/or mRNA degradation of target mRNAs involved in inflammation. MiR-124 is a crucial modulator of inflammation and innate immunity that could provide therapeutic restitution of physiological pathways lost in inflammatory diseases. A recently discovered small quinoline, ABX464, was shown to upregulate miR-124 in human immune cells. In vivo, in a proof-of-concept clinical study, ABX464 showed robust and consistent efficacy in ulcerative colitis (UC). In this review, we examine the current therapeutic options proposed for UC and discuss the drug candidate ABX464 in this context.

Strategies to Modulate MicroRNA Functions for the Treatment of Cancer or Organ Injury

Cancer and organ injury-such as that occurring in the perioperative period, including acute lung injury, myocardial infarction, and acute gut injury-are among the leading causes of death in the United States and impose a significant impact on quality of life. MicroRNAs (miRNAs) have been studied extensively during the last two decades for their role as regulators of gene expression, their translational application as diagnostic markers, and their potential as therapeutic targets for disease treatment. Despite promising preclinical outcomes implicating miRNA targets in disease treatment, only a few miRNAs have reached clinical trials. This likely relates to difficulties in the delivery of miRNA drugs to their targets to achieve efficient inhibition or overexpression. Therefore, understanding how to efficiently deliver miRNAs into diseased tissues and specific cell types in patients is critical. This review summarizes current knowledge on various approaches to deliver therapeutic miRNAs or miRNA inhibitors and highlights current progress in miRNA-based disease therapy that has reached clinical trials. Based on ongoing advances in miRNA delivery, we believe that additional therapeutic approaches to modulate miRNA function will soon enter routine medical treatment of human disease, particularly for cancer or perioperative organ injury. SIGNIFICANCE STATEMENT: MicroRNAs have been studied extensively during the last two decades in cancer and organ injury, including acute lung injury, myocardial infarction, and acute gut injury, for their regulation of gene expression, application as diagnostic markers, and therapeutic potentials. In this review, we specifically emphasize the pros and cons of different delivery approaches to modulate microRNAs, as well as the most recent exciting progress in the field of therapeutic targeting of microRNAs for disease treatment in patients.

Reduce and Control: A Combinatorial Strategy for Achieving Sustained HIV Remissions in the Absence of Antiretroviral Therapy

Human immunodeficiency virus (HIV-1) indefinitely persists, despite effective antiretroviral therapy (ART), within a small pool of latently infected cells. These cells often display markers of immunologic memory and harbor both replication-competent and -incompetent proviruses at approximately a 1:100 ratio. Although complete HIV eradication is a highly desirable goal, this likely represents a bridge too far for our current and foreseeable technologies. A more tractable goal involves engineering a sustained viral remission in the absence of ART––a “functional cure.” In this setting, HIV remains detectable during remission, but the size of the reservoir is small and the residual virus is effectively controlled by an engineered immune response or other intervention. Biological precedence for such an approach is found in the post-treatment controllers (PTCs), a rare group of HIV-infected individuals who, following ART withdrawal, do not experience viral rebound. PTCs are characterized by a small reservoir, greatly reduced inflammation, and the presence of a poorly understood immune response that limits viral rebound. Our goal is to devise a safe and effective means for replicating durable post-treatment control on a global scale. This requires devising methods to reduce the size of the reservoir and to control replication of this residual virus. In the following sections, we will review many of the approaches and tools that likely will be important for implementing such a “reduce and control” strategy and for achieving a PTC-like sustained HIV remission in the absence of ART.

Beyond one pill, once daily: current challenges of antiretroviral therapy management in the United States

Introduction: Modern antiretroviral therapy (ART) has revolutionized HIV treatment. ART regimens are now highly efficacious, well-tolerated, safe, often with one multi-drug pill, once-daily regimens available. However, clinical challenges persist in managing ART in persons with HIV (PWH), such as drug-drug interactions, side effects, pregnancy, co-morbidities, and adherence.Areas Covered: In this review, we discuss the ongoing challenges of ART for adults in the United States. We review the difficulties of initiating ART and maintaining therapy throughout adulthood and discuss new agents and strategies under investigation to address these issues. A PubMed search was utilized to identify relevant publications and guidelines through July 2019.Expert Opinion: Challenges persist in initiation and maintenance of ART. An individual's coexisting medical, social and personal factors must be considered in selecting and continuing ART to ensure safety, tolerability, and efficacy throughout adulthood. Continued development of new therapeutics and novel approaches to ART, such as long acting drugs or dual therapy, are needed to respond to many of these challenges. In addition, future research must address therapeutic disparities for populations historically underrepresented in clinical trials, including women, people aging with HIV, and those with complex comorbidities.

Cat and Mouse: HIV Transcription in Latency, Immune Evasion and Cure/Remission Strategies

There is broad scientific and societal consensus that finding a cure for HIV infection must be pursued. The major barrier to achieving a cure for HIV/AIDS is the capacity of the HIV virus to avoid both immune surveillance and current antiretroviral therapy (ART) by rapidly establishing latently infected cell populations, termed latent reservoirs. Here, we provide an overview of the rapidly evolving field of HIV cure/remission research, highlighting recent progress and ongoing challenges in the understanding of HIV reservoirs, the role of HIV transcription in latency and immune evasion. We review the major approaches towards a cure that are currently being explored and further argue that small molecules that inhibit HIV transcription, and therefore uncouple HIV gene expression from signals sent by the host immune response, might be a particularly promising approach to attain a cure or remission. We emphasize that a better understanding of the game of "cat and mouse" between the host immune system and the HIV virus is a crucial knowledge gap to be filled in both cure and vaccine research.