Safety and Antiviral Effects of Nebulized PC786 in a Respiratory Syncytial Virus Challenge Study.

PC786 is a nebulized nonnucleoside respiratory syncytial virus (RSV) polymerase inhibitor designed to treat RSV, which replicates in the superficial layer of epithelial cells lining the airways. Fifty-six healthy volunteers inoculated with RSV-A (Memphis 37b) were randomly dosed with either nebulized PC786 (5 mg) or placebo, twice daily for 5 days, from either 12 hours after confirmation of RSV infection or 6 days after virus inoculation. Viral load (VL), disease severity, pharmacokinetics, and safety were assessed until discharge. RSV infection was confirmed by reverse-transcription quantitative polymerase chain reaction with any positive value (intention-to-treat infected [ITT-I] population) or RSV RNA ≥1 log10 plaque-forming unit equivalents (PFUe)/mL (specific intention-to-treat infection [ITT-IS] population) in nasal wash samples. In the ITT-I population, the mean VL area under the curve (AUC) was lower in the PC786 group than the placebo group (274.1 vs 406.6 log10 PFUe/mL × hour; P = .0359). PC786 showed a trend toward reduction of symptom score and mucous weight. In ITT-IS (post hoc analysis), the latter was statistically significant as well as VL AUC (P = .0126). PC786 showed an early time to maximum plasma concentration, limited systemic exposure, and long half-life and consequently a 2-fold accumulation over the 5-day dosing period. PC786 was well tolerated. Nebulized PC786 demonstrated a significant antiviral effect against RSV, warranting further clinical study. ClinicalTrials.gov: NCT03382431; EudraCT: 2017-002563-18.

DeVincenzo J ，Cass L ，Murray A ，Woodward K ，Meals E ，Coates M ，Daly L ，Wheeler V ，Mori J ，Brindley C ，Davis A ，McCurdy M ，Ito K ，Murray B ，Strong P ，Rapeport G ... -  《-》

Late therapeutic intervention with a respiratory syncytial virus L-protein polymerase inhibitor, PC786, on respiratory syncytial virus infection in human airway epithelium.

Effective anti-respiratory syncytial virus (RSV) agents are still not available for clinical use. Current major targets are virus surface proteins, such as a fusion protein involved in viral entry, but agents effective after RSV infection is established are required. Here we have investigated the effects of late therapeutic intervention with a novel inhaled RSV polymerase inhibitor, PC786, on RSV infection in human airway epithelium. Air liquid interface-cultured bronchial or small airway epithelium was infected with RSVA2. PC786 was applied apically or basolaterally once daily following peak virus load on Day 3 post inoculation. Apical wash was collected daily for determination of viral burden by PCR and plaque assay (primary endpoints) and biomarker analyses. The effects were compared with those of ALS-8112, an anti-RSV nucleoside analogue, and GS-5806, a fusion-protein inhibitor, which were treated basolaterally. Late intervention with GS-5806 did not show significant anti-viral effects, but PC786 produced potent, concentration-dependent inhibition of viral replication with viral load falling below detectable limits 3 days after treatment commenced in airway epithelium. These effects were superior to those of ALS-8112. PC786 showed inhibitory activities against RSV-induced increases of CCL5, IL-6, double-strand DNA and mucin. The effects of PC786 were also confirmed in small airway epithelium. Late therapeutic intervention with the RSV polymerase inhibitor, PC786, reduced the viral burden quickly in human airway epithelium. Thus, PC786 demonstrates the potential to be an effective therapeutic agent to treat active RSV infection.

Brookes DW ，Coates M ，Allen H ，Daly L ，Constant S ，Huang S ，Hows M ，Davis A ，Cass L ，Ayrton J ，Knowles I ，Strong P ，Rapeport G ，Ito K ... -  《-》

Preclinical Characterization of PC786, an Inhaled Small-Molecule Respiratory Syncytial Virus L Protein Polymerase Inhibitor.

Although respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants and young children, attempts to develop an effective therapy have so far proved unsuccessful. Here we report the preclinical profiles of PC786, a potent nonnucleoside RSV L protein polymerase inhibitor, designed for inhalation treatment of RSV infection. PC786 demonstrated a potent and selective antiviral activity against laboratory-adapted or clinical isolates of RSV-A (50% inhibitory concentration [IC50], <0.09 to 0.71 nM) and RSV-B (IC50, 1.3 to 50.6 nM), which were determined by inhibition of cytopathic effects in HEp-2 cells without causing detectable cytotoxicity. The underlying inhibition of virus replication was confirmed by PCR analysis. The effects of PC786 were largely unaffected by the multiplicity of infection (MOI) and were retained in the face of established RSV replication in a time-of-addition study. Persistent anti-RSV effects of PC786 were also demonstrated in human bronchial epithelial cells. In vivo intranasal once daily dosing with PC786 was able to reduce the virus load to undetectable levels in lung homogenates from RSV-infected mice and cotton rats. Treatment with escalating concentrations identified a dominant mutation in the L protein (Y1631H) in vitro In addition, PC786 potently inhibited RSV RNA-dependent RNA polymerase (RdRp) activity in a cell-free enzyme assay and minigenome assay in HEp-2 cells (IC50, 2.1 and 0.5 nM, respectively). Thus, PC786 was shown to be a potent anti-RSV agent via inhibition of RdRp activity, making topical treatment with this compound a novel potential therapy for the treatment of human RSV infections.

Coates M ，Brookes D ，Kim YI ，Allen H ，Fordyce EAF ，Meals EA ，Colley T ，Ciana CL ，Parra GF ，Sherbukhin V ，Stockwell JA ，Thomas JC ，Hunt SF ，Anderson-Dring L ，Onions ST ，Cass L ，Murray PJ ，Ito K ，Strong P ，DeVincenzo JP ，Rapeport G ... -  《-》

A Randomized, Placebo-Controlled, Respiratory Syncytial Virus Human Challenge Study of the Antiviral Efficacy, Safety, and Pharmacokinetics of RV521, an Inhibitor of the RSV-F Protein.

Effective treatments for respiratory syncytial virus (RSV) infection are lacking. Here, we report a human proof-of-concept study for RV521, a small-molecule antiviral inhibitor of the RSV-F protein. In this randomized, double-blind, placebo-controlled trial, healthy adults were challenged with RSV-A Memphis-37b. After infection was confirmed (or 5 days after challenge virus inoculation), subjects received RV521 (350 mg or 200 mg) or placebo orally every 12 h for 5 days. The primary endpoint was area under the curve (AUC) for viral load, as assessed by reverse transcriptase quantitative PCR (RT-qPCR) of nasal wash samples. The primary efficacy analysis set included subjects successfully infected with RSV who received ≥1 dose of study drug. A total of 66 subjects were enrolled (n = 22 per group); 53 were included in the primary analysis set (RV521 350 mg: n = 16; 200 mg: n = 18; placebo: n = 19). The mean AUC of RT-qPCR-assessed RSV viral load (log10 PFU equivalents [PFUe]/ml · h) was significantly lower with RV521 350 mg (185.26; standard error [SE], 31.17; P = 0.002) and 200 mg (224.35; SE, 37.60; P = 0.007) versus placebo (501.39; SE, 86.57). Disease severity improved with RV521 350 mg and 200 mg versus placebo (P = 0.002 and P = 0.009, respectively, for AUC total symptom score [score × hours]). Daily nasal mucus weight was significantly reduced (P = 0.010 and P = 0.038 for RV521 350 mg and 200 mg, respectively, versus placebo). All treatment-emergent adverse events were grade 1 or 2. No subjects discontinued due to adverse events. There was no evidence of clinically significant viral resistance, and only three variants were detected. RV521 effectively reduced RSV viral load and disease severity in humans and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. NCT03258502.).

DeVincenzo J ，Tait D ，Efthimiou J ，Mori J ，Kim YI ，Thomas E ，Wilson L ，Harland R ，Mathews N ，Cockerill S ，Powell K ，Littler E ... -  《-》

EDP-938, a Respiratory Syncytial Virus Inhibitor, in a Human Virus Challenge.

Respiratory syncytial virus (RSV) infection causes substantial morbidity and mortality among infants, older adults, and immunocompromised adults. EDP-938, a nonfusion replication inhibitor of RSV, acts by modulating the viral nucleoprotein. In a two-part, phase 2a, randomized, double-blind, placebo-controlled challenge trial, we assigned participants who had been inoculated with RSV-A Memphis 37b to receive EDP-938 or placebo. Different doses of EDP-938 were assessed. Nasal-wash samples were obtained from day 2 until day 12 for assessments. Clinical symptoms were assessed by the participants, and pharmacokinetic profiles were obtained. The primary end point was the area under the curve (AUC) for the RSV viral load, as measured by reverse-transcriptase-quantitative polymerase-chain-reaction assay. The key secondary end point was the AUC for the total symptom score. In part 1 of the trial, 115 participants were assigned to receive EDP-938 (600 mg once daily [600-mg once-daily group] or 300 mg twice daily after a 500-mg loading dose [300-mg twice-daily group]) or placebo. In part 2, a total of 63 participants were assigned to receive EDP-938 (300 mg once daily after a 600-mg loading dose [300-mg once-daily group] or 200 mg twice daily after a 400-mg loading dose [200-mg twice-daily group]) or placebo. In part 1, the AUC for the mean viral load (hours × log10 copies per milliliter) was 204.0 in the 600-mg once-daily group, 217.7 in the 300-mg twice-daily group, and 790.2 in the placebo group. The AUC for the mean total symptom score (hours × score, with higher values indicating greater severity) was 124.5 in the 600-mg once-daily group, 181.8 in the 300-mg twice-daily group, and 478.8 in the placebo group. The results in part 2 followed a pattern similar to that in part 1: the AUC for the mean viral load was 173.9 in the 300-mg once-daily group, 196.2 in the 200-mg twice-daily group, and 879.0 in the placebo group, and the AUC for the mean total symptom score was 99.3, 89.6, and 432.2, respectively. In both parts, mucus production was more than 70% lower in each EDP-938 group than in the placebo group. The four EDP-938 regimens had a safety profile similar to that of placebo. Across all dosing regimens, the EDP-938 median time to maximum concentration ranged from 4 to 5 hours, and the geometric mean half-life ranged from 13.7 to 14.5 hours. All EDP-938 regimens were superior to placebo with regard to lowering of the viral load, total symptom scores, and mucus weight without apparent safety concerns. (ClinicalTrials.gov number, NCT03691623.).

Ahmad A ，Eze K ，Noulin N ，Horvathova V ，Murray B ，Baillet M ，Grey L ，Mori J ，Adda N ... -  《-》