ABSTRACT
INTRODUCTION: Vidofludimus calcium has shown anti-inflammatory effects in clinical trials of autoimmune diseases and recently demonstrated antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We performed a double-blind, randomized, placebo-controlled, phase 2 trial to evaluate the safety and efficacy of vidofludimus calcium in patients hospitalized for coronavirus disease 2019 (COVID-19) in Europe and the USA. METHODS: Patients aged 18 years or older who positive for COVID-19 were randomized (1:1) to receive placebo or 45 mg vidofludimus calcium for 14 days with both groups receiving standard-of-care treatment. The primary endpoint was the need for invasive ventilation after 28 days (ClinicalTrials.gov NCT04379271; EudraCT 2020-001264-28). RESULTS: Between June 12, 2020 and December 10, 2020, a total of 223 were randomized to receive either placebo (n = 112) or vidofludimus calcium (n = 111); three patients withdrew consent and were not treated. Eight (9%) patients in the placebo group and 12 (11%) patients in the vidofludimus calcium group needed invasive ventilation during the 28-day study period, which was lower than the assumed rate of 40%. Time to clinical improvement was shorter by approximately 1 day in the vidofludimus calcium group (15.0 days [90% CI 14.8-15.9]) compared to the placebo group (15.9 days [90% CI 14.9-19.9]). This effect was greatest in patients who initiated therapy within 9 days of symptom onset (3.8 days shorter in the vidofludimus calcium group). Higher trough concentrations of vidofludimus calcium were associated with quicker time to clinical recovery. The rate and timing of appearance of anti-SARS-CoV-2 antibodies were not different between groups. Serious adverse events occurred in 4 (4%) patients in the placebo group and 2 (2%) patients in the vidofludimus calcium group; treatment-emergent adverse events of increased severity related to COVID-19 occurred in 13 (12%) patients in the placebo group and 8 (7%) patients in the vidofludimus calcium group. Overall mortality was low (2%). CONCLUSIONS: These findings support vidofludimus calcium being safe and well tolerated in patients with COVID-19.
ABSTRACT
The nucleoside analog N4-hydroxycytidine (NHC) is the active metabolite of the prodrug molnupiravir, which has been approved for the treatment of COVID-19. SARS-CoV-2 incorporates NHC into its RNA, resulting in defective virus genomes. Likewise, inhibitors of dihydroorotate dehydrogenase (DHODH) reduce virus yield upon infection, by suppressing the cellular synthesis of pyrimidines. Here, we show that NHC and DHODH inhibitors strongly synergize in the inhibition of SARS-CoV-2 replication in vitro. We propose that the lack of available pyrimidine nucleotides upon DHODH inhibition increases the incorporation of NHC into nascent viral RNA. This concept is supported by the rescue of virus replication upon addition of pyrimidine nucleosides to the media. DHODH inhibitors increased the antiviral efficiency of molnupiravir not only in organoids of human lung, but also in Syrian Gold hamsters and in K18-hACE2 mice. Combining molnupiravir with DHODH inhibitors may thus improve available therapy options for COVID-19.
ABSTRACT
Currently, human infections with the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are accelerating the ongoing spread of the pandemic. Several innovative types of vaccines have already been developed, whereas effective options of antiviral treatments still await a scientific implementation. The development of novel anti-SARS-CoV-2 drug candidates demands skillful strategies and analysis systems. Promising results have been achieved with first generation direct-acting antivirals targeting the viral polymerase RdRp or the protease 3CLpro. Such recently approved or investigational drugs like remdesivir and GC376 represent a basis for further development and optimization. Here, we establish a multi-readout assay (MRA) system that enables the antiviral assessment and mechanistic characterization of novel test compounds, drug repurposing and combination treatments. Our SARS-CoV-2-specific MRA combines the quantitative measurement of several parameters of virus infection, such as the intracellular production of proteins and genomes, enzymatic activities and virion release, as well as the use of reporter systems. In this regard, the antiviral efficacy of remdesivir and GC376 has been investigated in human Caco-2 cells. The readouts included the use of spike- and double-strand RNA-specific monoclonal antibodies for in-cell fluorescence imaging, a newly generated recombinant SARS-CoV-2 reporter virus d6YFP, the novel 3CLpro-based FRET CFP::YFP and the previously reported FlipGFP reporter assays, as well as viral genome-specific RT-qPCR. The data produced by our MRA confirm the high antiviral potency of these two drugs in vitro. Combined, this MRA approach may be applied for broader analyses of SARS-CoV-2-specific antivirals, including compound screenings and the characterization of selected drug candidates.
ABSTRACT
The ongoing pandemic spread of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) demands skillful strategies for novel drug development, drug repurposing and cotreatments, in particular focusing on existing candidates of host-directed antivirals (HDAs). The developmental drug IMU-838, currently being investigated in a phase 2b trial in patients suffering from autoimmune diseases, represents an inhibitor of human dihydroorotate dehydrogenase (DHODH) with a recently proven antiviral activity in vitro and in vivo. Here, we established an analysis system for assessing the antiviral potency of IMU-838 and DHODH-directed back-up drugs in cultured cell-based infection models. By the use of SARS-CoV-2-specific immunofluorescence, Western blot, in-cell ELISA, viral yield reduction and RT-qPCR methods, we demonstrated the following: (i) IMU-838 and back-ups show anti-SARS-CoV-2 activity at several levels of viral replication, i.e., protein production, double-strand RNA synthesis, and release of infectious virus; (ii) antiviral efficacy in Vero cells was demonstrated in a micromolar range (IMU-838 half-maximal effective concentration, EC50, of 7.6 ± 5.8 µM); (iii) anti-SARS-CoV-2 activity was distinct from cytotoxic effects (half-cytotoxic concentration, CC50, >100 µM); (iv) the drug in vitro potency was confirmed using several Vero lineages and human cells; (v) combination with remdesivir showed enhanced anti-SARS-CoV-2 activity; (vi) vidofludimus, the active determinant of IMU-838, exerted a broad-spectrum activity against a selection of major human pathogenic viruses. These findings strongly suggest that developmental DHODH inhibitors represent promising candidates for use as anti-SARS-CoV-2 therapeutics.