February 15, 2021 by Ken

CTSC | Stenoparib and COVID-19

Senior Scientists

Experienced COVID-9 researchers testing coronavirus inhibitors.

Steen Knudsen

CSO of Allarity Therapeutics
A 30-year career in bioinformatics combined with lab work (primarily gene expression) and clinical trials (primarily cancer). More recently, focus on regulatory process (FDA), business development and global patenting as well.

Nathan Stone

Research Project Coordinator
Molecular and microbiologist interested in the genetics and ecology of infectious diseases, the population genetics of disease vectors, in relation to public health. He coordinates the laboratory processes for the CTSC.

Christopher T. French

Director of CTSC
An expert in host-pathogen interactions, Dr. French oversees the in vitro testing of COVID-19 at the CTSC. His independent research focuses on pathogenic mechanisms, ecology and developing new therapeutics for infectious diseases.

Paul S. Keim

Executive Director of PMI
With research centered on genomic analysis, Dr. Keim is the Cowden Endowed Chair of Microbiology at Northern Arizona University (NAU), the Director of Pathogen Genomics at the Translational Genomics Research Institute (TGen).

Abstract

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

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, that recently advanced to Phase 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 mM dosage of stenoparib – below the approximated 25.5 mM half-maximally effective concentration (EC50), combined with 0.5 mM 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.

Fig. S1. Stenoparib inhibits plaque formation in Calu-3 cells.

Abstract Importance

Stenoparib impedes virus entry and post-entry processes, an advantage over drugs that have a narrower target range.

New 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 Phase 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.