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.

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).

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.

An insight on promising strategies hoping to cure HIV-1 infection by targeting Rev protein-short review

Human immunodeficiency virus-1 (HIV-1) infection remains to be one of the major threats throughout the world. Many researchers are working in this area to find a cure for HIV-1. The group of the FDA approved drugs which are currently used against HIV-1 in the clinical practice include nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), integrase inhibitors (InIs), and protease inhibitors (PIs). Fixed dose combinations (FDCs) of these drugs are available and are used as per the anti-retroviral therapy (ART) guidelines. Despite these, unfortunately, there is no cure for HIV1 infection to date. The present review is focused upon describing the importance of a post-transcriptional regulatory protein "Rev", responsible for latent HIV-1 infection as a possible, and promising therapeutic target against HIV-1.

Safety, Pharmacokinetics, and Antiviral Activity of a Novel HIV Antiviral, ABX464, in Treatment-Naive HIV-Infected Subjects in a Phase 2 Randomized, Controlled Study

We investigated the safety and antiviral effects of an anti-HIV compound (ABX464) with a unique mechanism of viral replication inhibition. This was a randomized, double-blind, placebo-controlled, dose-ranging study in treatment-naive HIV-infected patients. Participants were assigned to eight groups; each group included eight subjects receiving either the study compound, ABX464 (n = 6), or the corresponding placebo (n = 2), according to a randomization code. The first dose administered was 25 mg, given once or 3 times a day over a 2- to 3-week period. Ascending doses of up to 150 mg were delivered after review of the safety data. The primary objective of the study was to assess the safety and tolerability of ABX464 after repeated oral administrations in subjects infected by HIV. Sixty-six subjects were enrolled and were randomized. Sixty-three subjects completed the study according to the study protocol. Twenty-one adverse events (AEs) were reported by 7 subjects out of 16 (44%) who received placebo, and 158 AEs were reported by 39 subjects out of 50 (78%) who received the study drug. In the ABX464 treatment group, all of these adverse events were mild to moderate. No subjects discontinued treatment due to drug-related AEs. Administration of ABX464 at up to 150 mg once a day was safe and well tolerated in HIV-infected subjects. An efficacy signal with respect to a reduction of the viral load by ABX464 was detected, mainly in subjects treated at the highest dose. Further studies will be required to demonstrate antiviral effects in HIV-infected subjects in combination with other antiretroviral therapies. (This study is registered on the ClinicalTrials.gov website under registration no. NCT02452242.)

Randomized Trial of Food Effect on Pharmacokinetic Parameters of ABX464 Administered Orally to Healthy Male Subjects

ABX464 is an antiviral that provides a novel approach to the reduction and control of HIV infection. Investigation of food influence is important in the optimization of treatment. An open-label, food effect, randomized study which included 2 groups of 24 subjects each was carried out to assess the bioavailability and safety of single (group 1) and repeated (group 2) oral doses of ABX464 (50 mg) under fed or fasted conditions. The maximum concentration (C_max) and the area under the concentration-time curve from time zero to infinity (AUC_0-∞) of ABX464 were demonstrated to increase with food after a single dose of ABX464 (219% and 188%, respectively). The apparent terminal elimination half-lives (t_1/2s) under fed and fasted conditions were comparable, at about 0.80 h. The median time to maximum concentration (T_max) was delayed from 1.5 to 2.8 h, and the ratio of the AUC_0-∞ obtained under fed conditions to the AUC_0-∞ obtained under fasted conditions (F_rel) was 2.69. Comparable results were obtained on day 1 and day 10 in group 2. The increases in C_max and AUC_0-∞ of the metabolite ABX464-N-glucuronide (ABX464-NGlc) were, however, much more limited when ABX464 was given with food. The t_1/2s were also comparable under the two conditions (around 100 h). Between day 1 and day 10, the C_max increased by 5% under the fasted condition and by 25% under the fed condition. The most common related treatment-emergent adverse events were headaches, vomiting, and nausea. It was concluded that food has a significant impact on the levels of ABX464 in plasma with a delay in absorption and increased relative bioavailability, with a lesser impact on its biotransformation into ABX464-NGlc. ABX464 was well tolerated under both fasted and fed conditions. (This study has been registered at ClinicalTrials.gov under registration no. NCT02731885.).