Stenoparib, an inhibitor of cellular poly (ADP-ribose) polymerase (PARP), blocks replication of the SARS-CoV-2 human coronavirusin vitro

Abstract

By late 2020, the coronavirus disease (COVID-19) pandemic, caused by SARS-CoV-2 has caused tens of millions of infections and over 1 million deaths worldwide. A protective vaccine and more effective therapeutics are urgently needed. We evaluated a new PARP inhibitor, stenoparib, which was recently advanced to Stage II clinical trials for treatment of ovarian cancer, for activity against human respiratory coronaviruses, including SARS-CoV-2, in vitro. Stenoparib exhibits dose-dependent suppression of SARS-CoV-2 multiplication and spread in Vero E6 monkey kidney and Calu-3 human lung adenocarcinoma cells. Stenoparib was also strongly inhibitory to the HCoV-NL63 human seasonal respiratory coronavirus. Compared to remdesivir, which inhibits viral replication downstream of cell entry, stenoparib impedes entry and post-entry processes as determined by time-of-addition (TOA) experiments. Moreover, a 10 μM dosage of stenoparib – below the approximated 25.5 μM half-maximally effective concentration (EC50), combined with 0.5 μM remdesivir suppressed coronavirus growth by more than 90%, indicating a potentially synergistic effect for this drug combination. Stenoparib as a standalone or as part of combinatorial therapy with remdesivir should be a valuable addition to the arsenal against COVID-19.ImportanceNew therapeutics are urgently needed in the fight against COVID-19. Repurposing drugs that are either already approved for human use or are in advanced stages of the approval process can facilitate more rapid advances toward this goal. The PARP inhibitor stenoparib may be such a drug, as it is currently in Stage II clinical trials for the treatment of ovarian cancer and its safety and dosage in humans has already been established. Our results indicate that stenoparib possesses strong antiviral activity against SARS-CoV-2 and other coronaviruses in vitro. This activity appears to be based on multiple modes of action, where both pre-entry and post-entry viral replication processes are impeded. This may provide a therapeutic advantage over many current options that have a narrower target range. Moreover, our results suggest that stenoparib and remdesivir in combination may be especially potent against coronavirus infection.

Stenoparib, an inhibitor of cellular poly (ADP-ribose) polymerases (PARPs), blocks in vitro replication of SARS-CoV-2 variants

“…Plaques are areas of dead or destroyed cells and appear as small, clear regions in an infected cell monolayer after fixation and staining with crystal violet. We combined 2.5, 5.0, and 10 μM doses of stenoparib with the previously reported EC50 of remdesivir (0.5 μM) [6]. The 3 control types were 1) infected and untreated cells, 2) uninfected and untreated cells, and 3) infected cells treated with a combination of camostat mesylate and E64d (CE), which are protease inhibitors that prevent spike protein cleavage and virus entry into the cell [12].…”

“…We recently published a study on the activity of a poly (ADP-ribose) polymerase (PARP) inhibitor, stenoparib, also known as 2X-121, which inhibits viral replication by affecting pathways of the host [6] as opposed to targeting viral replication. ADP-ribosylation (ADPR) pathways may have either anti-or pro-viral properties, and their importance in host-virus interactions is becoming increasingly recognized [7].…”

“…ADP-ribosylation (ADPR) pathways may have either anti-or pro-viral properties, and their importance in host-virus interactions is becoming increasingly recognized [7]. Unlike remdesivir, which inhibits viral replication downstream of entry into the cell, stenoparib inhibits virus entry and post-entry processes [6].…”

“…Stenoparib inhibited the SARS-CoV-2 USA-WA1/2020 virus and the HCoV-NL63 human seasonal respiratory coronavirus in vitro, exhibiting dose-dependent suppression of virus multiplication and cell-cell spread in cell culture [6]. Stenoparib exhibits a unique dual activity against the PARP1, 2 and PARP5a, 5b (tankyrase 1, 2) enzymes, which are important intermediates in the Wnt/β-catenin immune checkpoint [8,9].…”

The K18-hACE2 Transgenic Mouse Model Recapitulates Non-Severe and Severe COVID-19 in Response to Infectious Dose of SARS-CoV-2 Virus

“…A one-step RT-PCR kit (BioRad) was used to detect the viral RNA using Applied Biosystems QuantStudio 12K Flex Real-Time PCR System with the following cycling protocol: reverse transcription at 50°C for 10 minutes; hot start at 95°C for 10 minutes; and 40 cycles of denaturation at 95°C for 10 seconds and annealing at 60°C for 30 seconds. The primer sequences were CoV2-S_19F (5’ -GCTGAACATGTCAACAACTC-3’) and CoV2-S_143R (5’ -GCAATGATGGATTGACTAGC-3’), which were designed to target a 125 bp region of the SARS-CoV-2 spike protein (31). The standard samples were serial 10-fold dilutions of a known copy number of the HKU1 virus.…”